preparation and application of sulfonated carbon catalyst
TRANSCRIPT
PREPARATION AND APPLICATION OF SULFONATED
CARBON CATALYST FOR BIODIESEL PRODUCTION
FROM WASTE COOKING OIL AND FURFURAL
PRODUCTION FROM XYLOSE
BY
MISS TRAN THI TUONG VI
A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF
THE REQUIREMENTS FOR DEGREE OF
MASTER OF SCIENCE (CHEMISTRY)
DEPARTMENT OF CHEMISTRY
FACULTY OF SCIENCE AND TECHNOLOGY
THAMMASAT UNIVERSITY
ACADEMIC YEAR 2016
COPYRIGHT OF THAMMASAT UNIVERSITY
PREPARATION AND APPLICATION OF SULFONATED
CARBON CATALYST FOR BIODIESEL PRODUCTION
FROM WASTE COOKING OIL AND FURFURAL
PRODUCTION FROM XYLOSE
BY
MISS TRAN THI TUONG VI
A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF
THE REQUIREMENTS FOR DEGREE OF
MASTER OF SCIENCE (CHEMISTRY)
DEPARTMENT OF CHEMISTRY
FACULTY OF SCIENCE AND TECHNOLOGY
THAMMASAT UNIVERSITY
ACADEMIC YEAR 2016
COPYRIGHT OF THAMMASAT UNIVERSITY
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Thesis Tittle PREPARATION AND APPLICATION OF
SULFONATED CARBON CATALYST FOR
BIODIESEL PRODUCTION FROM WASTE
COOKING OIL AND FURFURAL
PRODUCTION FROM XYLOSE
Author Miss Tran Thi Tuong Vi
Degree Master of Science
Major Field/Faculty/University Department of Chemistry,
Faculty of Science and Technology,
Thammasat University
Thesis Advisor Assistant Professor Chanatip Samart, D.Eng.
Thesis Co-advisor Associate Professor Prasert Reubroycharoen, D.Eng.
Academic Years 2016
ABSTRACT
This research investigated the preparation and utilization of carbon solid
acid catalyst (CM-SO3H) in both biodiesel production from waste cooking oil and
furfural production from xylose. The carbon solid acid catalyst was prepared by
sequential xylose hydrothermal carbonization and sulfonation. The CM-SO3H catalyst
was characterized the physicochemical properties and morphology by Scanning
Electron Microscope (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer-
Emmett-Teller (BET) and Fourier Transform Infrared spectroscopy (FT-IR). The acid
capacity of CM-SO3H catalyst was determined by both titration with 0.1N sodium
hydroxide and temperature-programmed desorption of ammonia (NH3-TPD). The
surface area and acidity of the catalyst were 86 m2/g and 1.38 mmol/g, respectively.
The different experimental parameters were studied including catalyst loading (wt.%),
reaction time (h), reaction temperature (C) and molar ratio of feedstock. The optimized
condition of biodiesel production was 110C for 2 h to obtain 89.6% yield. Whereas
the optimized reaction condition of xylose dehydration was 155C for 2h. From this
study, this catalyst was not only approach green chemistry concept as waste utilization,
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less chemical, safe and environmentally friendly but it also performed the good catalytic
activity nearly conventional acid catalyst.
Keywords: Carbon microsphere, Carbon solid acid catalyst, Biodiesel,
Furfural, Xylose dehydration.
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ACKNOWLEDGEMENTS
During the time to study at Thammasat University as a student of master
degree, I am deeply thankful for everyone who shared the knowledge, the experience,
and the advice throughout to complete my thesis.
First of all, I would like to express my special thanks of gratitude to my
advisor, Asst. Prof. Dr. Chanatip Samart for his valuable advice, motivation,
encouragement and kindly support. His immense knowledge, enthusiasm and whole-
heartedness would give me the opportunity for my future career. I came to know about
so many new things. My thankfulness is also expressed to my co-advisor, Assoc. Prof.
Dr. Prasert Reubroycharoen, for his encouragement and sound guidance.
In addition, I would like to acknowledge Asst. Prof. Dr. Suwadee
Kongparakul Asst. Prof. Dr. Thongthai Wittoon attending as chairman and member of
my thesis committee, respectively, as well as for their helpful discussion, insightful
comments, and suggestions. Dr. Narong Chanlek from the Thailand Synchrotron Light
Research Institute for assistance in XPS analysis.
I would also like to present acknowledgment to Faculty of Science and
Technology, Thammasat University for grant support to study Master of Science
program in Chemistry (Thammasat University's Scholarship for AEC Scholarship). The
financial support provided by The Thailand Research Fund and National University
project, Thammasat University. The Central Scientific Instrument Center, Faculty of
Science and Technology, Thammasat University. I thank all my labmates and my
friends for their friendly, helpful and kindness to help directly and indirectly to
complete my thesis.
Finally, I would like to express my deepest gratitude to my parents for
encouraging, understanding, loving and supporting me spiritually throughout my life.
Much love!
Miss Tran Thi Tuong Vi
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TABLE OF CONTENTS
ABSTRACT (1)
ACKNOWLEDGEMENTS (3)
LIST OF TABLES (7)
LIST OF FIGURES (8)
CHAPTER 1 INTRODUCTION 1
1.1 Thesis motivation 1
1.2 Objectives of the research 3
1.3 Scope of the research 4
CHAPTER 2 REVIEW OF LITERATURE 5
2.1 Renewable resources 5
2.2.1 Biomass 6
2.2.1.1 Lignocellulose biomass 7
2.2.1.2 Xylose 9
2.2 Biodiesel 12
2.2.1 Transesterification and Esterification 14
2.2.2 Transesterification process mechanism 15
2.3 Furfural 17
2.4 Catalyst 19
2.4.1 Homogeneous catalyst 20
2.4.2 Heterogenous catalyst 20
2.5 Carbon solid acid catalyst (CM-SO3H) 21
2.6 Literature reviews 23
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CHAPTER 3 RESEARCH METHODOLOGY 31
3.1 Materials 31
3.1.1 Chemicals 31
3.1.2 Equipments 32
3.2 Methods 32
3.2.1 Preparation of carbon solid acid catalyst (CM-SO3H) 32
3.2.2 Characterization of catalyst 34
3.2.2.1 Study the morphology of catalyst 34
3.2.2.2 Study the textural analysis 34
3.2.2.3 Study the functional group 34
3.2.2.4 Study the properties of acid sites 34
3.2.3 Catalytic activity in biodiesel production from waste cooking oil 35
3.2.3.1 Biodiesel production 35
3.2.3.2 FAME analysis 35
3.2.3.3 Catalyst reusability 36
3.2.4 Catalytic activity in furfural production via xylose dehydration 36
3.2.4.1 Dehydration of xylose 36
3.2.4.2 Product analysis 37
CHAPTER 4 RESULTS AND DISCUSSION 38
4.1 Characterization of the carbon catalyst 38
4.1.1 N2 sorption analysis 38
4.1.2 The morphology of catalyst 40
4.1.3 The properties of acid sites 41
4.1.4 The functional group 43
4.2 Catalytic activity in biodiesel production from waste cooking oil 45
4.2.1 Effect of reaction temperature 46
4.2.2 Effect of reaction time 47
4.2.3 Effect of catalyst loading 48
4.2.4 Reusability 49
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4.3 Catalytic activity in furfural production via xylose dehydration 53
4.3.1 Effect of reaction temperature 53
4.3.2 Effect of reaction time 54
4.3.3 Effect of catalyst loading 55
CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS 58
5.1 Conclusions 58
5.2 Recommendations 59
REFERENCES 60
APPENDICES 67
APPENDIX A 68
Carbon microsphere characterization 68
APPENDIX B 72
Standard calibration curve preparation 72
APPENDIX C 75
By-products of xylose dehydration 75
BIOGRAPHY 80
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LIST OF TABLES
Tables Page
Table 2.1 The chemical composition and types of lignocellulosic biomass [2] 8
Table 2.2 Comparison of fuel properties of petroleum-diesel fuel and B100 biodiesel
fuel [30] 13
Table 2.3 Physical properties of furfural [37] 18
Table 2.4 Comparison of homogeneous and heterogeneous catalyst [38] 20
Table 2.5 Comparison of reaction conditions, product yields for thermochemical
conversion processes to carbon solid. [41] 21
Table 3.1 List of the chemicals used in this research 31
Table 3.2 List of the instrument used in this research 32
Table 3.3 The program of column temperature 36
Table 4.1 Textural properties and acidity of carbon microspheres, and catalysts. 40
Table 4.2 The chemical composition and physicochemical properties of waste
cooking oil 45
Table A1. Physical properties of carbon microspheres at 190C – 50wt.% (xylose
concentration) with different reaction time. 71
Table C1. Yield of by-products under xylose dehydration with CM-SO3H catalyst at
different reaction temperature for 2 h and 50 wt.% catalyst loading 75
Table C2. Yield of by-products under xylose dehydration with CM-SO3H catalyst at
different reaction time, 155C and 50 wt.% catalyst loading 76
Table C3. Yield of by-products under xylose dehydration with CM-SO3H catalyst at
155C for 2h and diffent catalyst loading 76
Table C4. Yield of by-products under xylose dehydration with P-C-SO3H catalyst at
155C for 2h and 25 wt.% catalyst loading 77
Table C5. Chemical structure of by-products 78
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LIST OF FIGURES
Figures Page
Figure 1.1 The main components and structure of lignocellulose [2] 2
Figure 2.1 Comparison between renewable energy and non-renewable energy 5
Figure 2.2 The conversion technology of biomass [19] 6
Figure 2.3 The structure and main components of lignocellulose biomass [20] 8
Figure 2.4 Mechanism of furfural production from xylose dehydration (a) via
enolization, (b) β-elimination, (c) via cyclic intermediates [24] 11
Figure 2.5 Mechanism of the formation of carbon microsphere prepared
hydrothermal from xylose [8] 12
Figure 2.6 Esterification reaction of free fatty acid with alcohol [31] 14
Figure 2.7 Transesterification reaction of triglycerides with alcohol [31] 14
Figure 2.8 Mechanism of base catalysed transesterification process [35] 16
Figure 2.9 Mechanism of acid catalysed transesterification process [35, 36] 17
Figure 2.10 Chemical structure of furfural 17
Figure 2.11 Chemicals derived from furfural [37] 19
Figure 2.12 Formation of CM-SO3H structure 23
Figure 2.13 The overall paths to produce furfural from xylose in the presence of a
single bronsted acid catalyst and of both lewis and bronsted acid catalysts [60] 28
Figure 3.1 Schematic diagram of synthesized CM-SO3H catalyst 33
Figure 4.1. Nitrogen sorption isotherms of (a) carbon microsphere (CM): overlay 40
units; (b) solid acid catalyst (CM-SO3H): overlay 80 units and (c) porous carbon
solid acid catalyst (P-C-SO3H) 39
Figure 4.2 Pore size distribution of (a) carbon microsphere; (b) carbon solid acid
catalyst (CM-SO3H) and (c) porous carbon solid acid catalyst (P-C-SO3H) 40
Figure 4.3 SEM microphotograph of (a) carbon microsphere; (b) carbon solid acid
catalyst (CM-SO3H). 41
Figure 4.4 NH3-TPD profile of (a) carbon solid acid catalyst (CM-SO3H) and (b)
porous carbon solid acid catalyts (P-C-SO3H) 42
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Figure 4.5 FTIR spectral of (a) carbon microsphere, (b) CM-SO3H and (c) P-C-SO3H
44
Figure 4.6 XPS spectra of CM-SO3H 45
Figure 4.7 FAME yield with different reaction temperatures at reaction time 6 h,
molar ratio of oil/methanol 1:9.35, and catalyst loading 10 wt.%. 47
Figure 4.8 FAME yield with different reaction times at reaction temperature 110C,
molar ratio of oil/methanol 1:9.35, and catalyst loading 10 wt.%. 48
Figure 4.9 FAME yields with different catalyst loading at reaction temperature
110 C for 2 h; molar ratio of oil/methanol is 1:9.35. 49
Figure 4.10 FAME yield with spent catalyst at reaction temperature 110 C for 2 h
and 10 wt. % catalyst loading 50
Figure 4.11 (a) N2 sorption isotherm and (b) pore size distribution of spent sulfonated
carbon catalyst after 3 cycles of reused 51
Figure 4.12 SEM microphotograph of spent sulfonated carbon catalyst of biodiesel
production. 52
Figure 4.13 NH3-TPD profile of spent sulfonated carbon catalyst after 3 cycles of
reused 53
Figure 4.14 Catalytic performance including xylose conversion, furfural yield and
furfural selectivity with different reaction temperature at reaction time 2h and 50
wt.% catalyst loading 54
Figure 4.15 Catalytic performance including xylose conversion, furfural yield and
furfural selectivity with different reaction times at reaction temperature 155C and
50 wt.% catalyst loading. 55
Figure 4.16 Catalytic performance including xylose conversion, furfural yield and
furfural selectivity with different catalyst loading at reaction temperature 155C for
2h. 56
Figure 4.17 Catalytic performance including xylose conversion, furfural yield and
furfural selectivity between CM-SO3H and P-C-SO3H catalysts at reaction
temperature 155C for 2 h and 25 wt.% catalyst loading. 57
Figure A1. Yield of carbon microsphere obtained from different conditions of
hydrothermal. 68
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Figure A2. SEM micrograph of carbon microsphere at 190C – 50wt.% (xylose
concentration) with different reaction time. 69
Figure A4. N2 sorption of carbon microsphere at 190C – 50wt.% (xylose
concentration) with different reaction time. 70
Figure A5. Van Krevelen diagram of carbon microsphere from different conditions
of hydrothermal. 71
Figure B1. Standard calibration curve for furfural production (HPLC) 72
Figure B2. Standard calibration curve for xylose conversion (HS-GC-MS) 73
1
CHAPTER 1
INTRODUCTION
1.1 Thesis motivation
Nowadays, research in chemistry will be tendency to explore and
development toward green chemistry that is mean environmental friendly, safe for
human health and supply for people the suitable products, less toxic and completely
recyclability. In the issue of future energy, fossil fuels are running out, we may face an
ecological destroy of exceptional scale due to the degradation of natural capital and loss
in ecosystem services such as air pollution, water pollution, etc. From these reasons
alternative and clean fuels has been interested to replace the fossil fuel. The scientists
have the most important responsibility find new energy resources. [1] There are
abundant and large quantities renewable resources every year such as agricultural crops
and residues, sewage, urban solid waste, animal residues, industrial residues, forestry
crops and residues, etc. It is a very complicated energy system with a multitude of
variations, also suitable for agricultural countries such as Viet Nam, Thailand, and
Malaysia, etc. They can replace those derived from petrochemical resources is very
significant to improve economic benefits and reduce environmental pollution. One of
the most important renewable energy sources is a lignocellulose biomass. [2, 3]
Lignocellulose biomass contained different structures of natural
macromolecule mainly of cellulose, hemicellulose and lignin were shown in Figure
1.1. It has been projected as an abundant carbon-neutral renewable source.
Lignocellulose feedstocks have important advantages over other feedstocks supplies in
this research because they are the non-edible portion of the plant therefore, they are a
non-food resource. [3] The heteropolymer as hemicellulose is composed of different 5-
and 6-carbon monosaccharide units: pentoses (xylose, arabinose), hexoses (mannose,
glucose, galactose) and acetylated sugars. [4] The major monomer of hemicellulose is
a xylose could be converted to a diversified of products such as microsphere structure
of carbon polymer or carbon microsphere, ethanol, furfural, furan, bio-ethanol, xylitol
and furfuryl alcohol, etc. Among these derivatives, carbon microsphere is the important
2
material and is interested from scientists. It has been applied in many applications such
as catalyst support, carbon fixation, CO2 sequestration, adsorbent, electrode, sensors,
and capacitor, etc. [5, 6] The process allows not only concentrating the energy content
from biomass into a solid biofuel but also generating liquid residue that could be used
as fertilizer on agricultural plantations. [1]
Figure 1.1 The main components and structure of lignocellulose [2]
In recent years, there have been numerous of articles reported application
as well as the method to synthesized the carbon-based catalysts via hydrothermal
carbonization (HTC). [7, 8] Hydrothermal carbonization is also known as thermal
treatment of organic substance under water media at high temperature and high
pressure. During the reaction, organic components of the biomass degraded and re-
polymerize into carbon solid. [9] HTC is one of a method has been interested over the
3
last several years because they do not only produce value-added products at high carbon
material yields with low cost but also facile preparation, high stability, non-toxicity and
green method.
The carbon solid acid catalyst, which is heterogeneous acid catalyst was
selected to catalyze for biodiesel production from waste cooking oil and xylose
dehydration to furfural with outstanding in stability, less toxicity, large specific surface
area, high dispersal ability, easily to synthesize, strong acidity and low cost. This
catalyst can be easily reused after reaction. Moreover, acid catalyst plays an important
role in biomass conversion processes for producing chemicals and fuels. [1] Compared
with homogeneous acid catalyst (H2SO4, HCl, CH3COOH), the homogeneous catalyst
has several disadvantages such as toxic, corrosive to equipment, produce more waste
water, difficult to separate and reuse, etc. [10]
Therefore, carbon solid acid catalyst containing sulfonic acid (SO3H) group
would be prepared by hydrothermal carbonization and sufonation from xylose. Carbon
solid acid catalysts (CM-SO3H) would act as a catalyst for simultaneously esterification
and transesterification to produce biodiesel from waste cooking oil and synthesis the
furfural through dehydration reaction of xylose. The optimization condition of biodiesel
and furfural production were also studied with vary parameters including reaction
temperature (C), reaction time (h), catalyst loading (wt.%). In this concept, we would
like to propose the principles of green carbon science and application of green
chemistry to acid heterogeneous catalyst.
1.2 Objectives of the research
1. To study formation of carbon microsphere by hydrothermal
carbonization of xylose.
2. To study sulfonation of carbon for acid catalyst.
3. To apply the sulfonated carbon catalyst for biodiesel production from
waste cooking oil and furfural production from xylose.
4
1.3 Scope of the research
1. Study the synthesis carbon microsphere by hydrothermal carbonization
of xylose.
2. Study the sulfonation condition to form sulfonated carbon catalyst (CM-
SO3H)
3. Study experimental condition of biodiesel production from waste
cooking oil with methanol by CM-SO3H catalyst using autoclave system such as
catalyst loading, methanol to oil ratio, reaction temperature and reaction time.
4. Study experimental condition of xylose dehydration by CM-SO3H
catalyst such as catalyst loading wt.%, reaction temperature and reaction time.
5
CHAPTER 2
REVIEW OF LITERATURE
2.1 Renewable resources
Renewable resources are one that will not run out of it; could be protected
the environment from toxic pollutions, which in turn keep people healthier. The energy
of life cycles of renewable and non renewable energy were shown in Figure 2.1.
Renewable energy does not produce greenhouse gases, carbon emissions, radioactive
waste, or acid rain. Renewable resources are also cheaper, stabilize and more
economically than other sources of non-renewable resources. [11-13] Renewable
energy could be categorized based on origin such as solar energy, wind energy,
hydropower energy, geothermal energy and biomass energy. It has been developed and
commercially well investigated in the latest year. [11, 14-16] Therefore, there are
several studies have focused on renewables energy. One of the most interested in is
biomass energy source.
Figure 2.1 Comparison between renewable energy and non-renewable energy
6
2.2.1 Biomass
Biomass is derived by a natural organic material based on carbon,
hydrogen, and oxygen. Biomass sources are available in countrified and urban areas of
all countries. The compositions and structure of biomass are very diversified and are
affected by origin, age, climatic conditions, and location. [17] Biomass is an alternative
resource, play an important role in producing of carbon-neutral fuels as well as
providing feedstocks for the production of biofuels and another chemicals. The
advantages of biomass have the potential solved many environmental issues, especially
global warming and greenhouse gases emissions. It recovers CO2 from air emissions in
the fuel combustion engine, then the process of photosynthesis to give clean energy and
reduce the CO2 level in the atmosphere is called close carbon dioxide cycles. For this
reason, it is recognized that biomass is an important and abundant energy source could
be replaced to solve the problem of depleted of fossil fuels. [18]
The conversion of biomass can be accomplished by different methods
which are divided into: thermal, thermochemical, chemical, and biochemical methods
were summarised in Figure 2.2.
Figure 2.2 The conversion technology of biomass [19]
7
2.2.1.1 Lignocellulose biomass
Lignocellulose biomass is a generic terminology for describing the plants
biomass. It is the most abundant biomass resource contained mainly of the
polysaccharides cellulose, hemicellulose and lignin (Figure 2.3).
The major component of lignocellulose biomass is cellulose that is a homo-
polysaccharides with same monomer (Glucose). Its crystalline structure consist of
intramolecular and intermolecular hydrogen bonding, which possessing high chemical
stability with binds the glucose units. Hemicellulose is the second abundant renewable
biomass after cellulose, which is a random and amorphous structure. It is a hetro-
polysaccharides with different sugar monomers composed of different 5- and 6-carbon
monosaccharide units (xylose, glucose, mannose, galactose, uronic acid). The third
component, lignin is an amorphous heteropolymer with three-dimensional aromatic
polymer of phenyl propane units. [2], [20], [21]
Cellulose, hemicellulose and lignin are not uniformly distributed in the
plant cell. Normally, lignocellulosic biomass consists of 35–50% cellulose, 20–35%
hemicellulose, and 10–25% lignin. There are also other fractions such as proteins, oils,
and ash. [2]
8
Figure 2.3 The structure and main components of lignocellulose biomass [20]
The lignocellulose biomass can be classified in four particular types as
follow: Hardwood, Softwood, Agricultural waste, Grasses was shown as Table 2.1.
Table 2.1 The chemical composition and types of lignocellulosic biomass [2]
Lignocellulose biomass Cellulose (%) Hemicellulose
(%)
Lignin
(%)
Hard wood Poplar 50.8–53.3 26.2–28.7 15.5–16.3
Oak 40.4 35.9 24.1
Eucalyptus 54.1 18.4 21.5
Softwood Pine 42.0–50.0 24.0–27.0 20.0
Douglas fir 44.0 11.0 27.0
Spruce 45.5 22.9 27.9
9
Agricultural
waste Wheat Straw 35.0–39.0 23.0–30.0 12.0–16.0
Barley Hull 34.0 36.0 13.8-19.0
Barley Straw 36.0-43.0 24.0-33.0 6.3-9.8
Rice Straw 29.2–34.7 23.0–25.9 17.0–19.0
Rice Husks 28.7–35.6 12.0–29.3 15.4–20.0
Oat Straw 31.0–35.0 20.0–26.0 10.0–15.0
Ray Straw 36.2–47.0 19.0–24.5 9.9–24.0
Corn Cobs 33.7–41.2 31.9–36.0 6.1–15.9
Corn Stalks 35.0–39.6 16.8–35.0 7.0–18.4
Sugarcane
Bagasse 25.0–45.0 28.0–32.0 15.0–25.0
Sorghum
Straw 32.0–35.0 24.0–27.0 15.0–21.0
Grasses Grasses 25.0–40.0 25.0–50.0 10.0–30.0
Switchgrass 35.0–40.0 25.0–30.0 15.0–20.0
Lignocellulose biomass is an important component of the major food crops,
it is the non-edible portion of the plant, which is plentiful feedstock to fuels, polymers
and chemicals. It has an advantage over other biomass because it can be produced
quickly, lower cost than food crops and used as a raw material for the production of
alternative fuels without impacting in the world's food supply chain. Therefore,
lignocellulose is one of the most interested biomass resources in nature. [2], [20]
2.2.1.2 Xylose
Xylose, one of carbohydrate is sugar that categorized as a monosaccharide
of the aldopentose type, contained five carbon atoms and included a formyl functional
group. It is a first separated from wood and derived from hemicellulose, one of the main
components of biomass. Like most sugars, it can adopt several structures depending on
conditions. With its free carbonyl group, it is a reducing sugar. [22] D-Xylose is widely
10
applied industries include pharmaceutical (as intermediate: in medicine
manufacturing); food production (as sweetener in beverage and food); cosmetics (as
humectant: in cleanser, beauty creams and lotions to maintain the moisture); human
consumption; agriculture/animal feed, etc. [23] Moreover, xylose is a forerunner to
synthetic polymers, a solvent in industry and various chemicals such as carbon
microsphere, ethanol, furfural, furan, bio-ethanol, xylitol and furfuryl alcohol, etc.
There are many conversion methods of xylose into a variety of products such as xylose
fermentation to ethanol, xylose dehydration to furfural, electrochemical reduction of
xylose to xylitol, hydrothermal carbonization.
Xylose and other five carbon sugars undergo dehydration, losing three
water molecules to become furfural under simultaneous of heat and acid catalyst. More
than one reaction mechanism of furfural production from xylose dehydration has been
proposed in different studies based on different techniques, and reaction conditions
could be classified in three kinds as shown in Figure 2.4 [22, 24]
- Start from the acyclic form of the pentoses, either via a 1,2-enediol
intermediate 2 and next dehydration. (Figure 2.4 a)
- Or directly via a 2,3-(α,β-) unsaturated aldehyde 4 (Figure 2.4 b)
- Start from the pyranose form of the pentoses, the acid catalyst covert
xylose to the 2,5-anhydroxylose furanose intermediate and then
dehydrated to furfural (Figure 2.4 c)
11
Figure 2.4 Mechanism of furfural production from xylose dehydration (a) via
enolization, (b) β-elimination, (c) via cyclic intermediates [24]
Mechanism of xylose under hydrothermal carbonization process to carbon
microsphere was studied as shown in Figure 2.5. According to a current study on
hydrothermal carbonization of polysaccharides by Sevilla and Fuertes [25], the carbon
microsphere was formed follow four steps:
(1) Dehydration and fragmentation of sugars;
12
(2) Undergoes polymerization or condensation reactions of the dehydrated
and fragmented products;
(3) Aromatization of the polymers (by intermolecular dehydration);
(4) Nucleation growth by diffusion and linkage of species from the solution
to the nuclei surface. Besides that, xylose was decomposed to a various organic product
such as lactic acid, formic acid, acetic acid, fructose, HMF, furfural, etc. [26]
Figure 2.5 Mechanism of the formation of carbon microsphere prepared
hydrothermal from xylose [8]
2.2 Biodiesel
Biodiesel (fatty acid methyl or ethyl esters) is a kind of renewable fuel to
replace petroleum diesel. It is biodegradable, non-toxic, less harmful emissions,
13
environmentally friendly, safe to handle and high cetane number (a measurement of the
combustion quality of diesel fuel during compression ignition). Biodiesel production
could be derived from either edible plant oils including animal fats (biodiesel first
generation); non-edible plant oils (biodiesel second generation) such as leaves and
stems of plants, biomass derived from waste, and oils seeds; microalgae (biodiesel third
generation) or used edible oils (normally called Waste Cooking Oil; WCO). The
production of biodiesel from WCO is one of the solution for solving the simultaneous
problems of environment pollution and energy scarcity. Moreover, to reduce the cost
of biodiesel production, WCO would be a good choice as a raw material because of it
is cheaper than edible plant oils and other feedstocks. [27], [28], [29] Besides, the
properties of biodiesel is similar to petroleum diesel (Table 2.2)
Table 2.2 Comparison of fuel properties of petroleum-diesel fuel and B100 biodiesel
fuel [30]
Property Diesel Biodiesel Unit
Fuel Standard ASTM D975 ASTM D6751 -
Lower Heating Value 12905 11817 Btu/gal
Kinematic Viscosity@40C 1.3 – 4.1 1.9 – 6.0 mm2/s
Specific Gravity@60C 0.85 0.88 kg/l
Density 7.079 7.328 lb./gal
Water and Sediment 0.05 max 0.05 max % Vol.
Carbon 87 77 wt.%
Hydrogen 13 12 wt.%
Oxygen 0 11 -
Sulfur 0.0015 0.0 – 0.0024 wt. %
Boiling Point 180 – 340 315 – 350 C
Flash Point 60 – 80 130 – 170 C
Cloud Point (-15) – 5 (-3) – 12 C
14
Pour Point (-35) – (-15) (-15) – 10 C
Cetane Number 40 – 55 47 – 65 -
Lubricity SLBOCLE 2000 – 5000 > 7000 grams
Lubricity HFRR 300 – 600 < 300 microns
2.2.1 Esterification and Transesterification
Esterification is the process use to convert these free fatty acid and alcohols
to form alkyl ester and water (Figure 2.6). The esterification reaction is both slow and
reversible.
Figure 2.6 Esterification reaction of free fatty acid with alcohol [31]
Transesterification or also called alcoholysis is the process use to convert
these triglycerides to form biodiesel and glycerol (Figure 2.7). The suitable alcohols
use for this process are methanol, ethanol, propanol, butanol, and amyl alcohol.
Methanol and ethanol are utilized most usually, especially methanol because of its low
cost and its physical and chemical advantages.
Figure 2.7 Transesterification reaction of triglycerides with alcohol [31]
15
2.2.2 Transesterification process mechanism
Transesterification process could be divided into two groups:
Supercritical transesterification or non-catalytic transesterification process
is the reaction produce biodiesel without catalytic under high temperature, high
pressure and requires high alcohol to oil molar ratio. Therefore, high cost, low reaction
conversion because the degradation of the fatty acid esters formed, the glycerol formed
react with other components at high temperature. [32], [33]
Catalytic transesterification process is the reaction produce biodiesel using
a catalyst (alkaline, acid or enzymatic catalyst). [34], [35], [36]
- Alkaline catalyst (NaOH, KOH, CH3ONa) has been interested in by many
researchers because it's cheap and available. However, this catalyst suitable for oils
containing not over than 3% of free fatty acid and water content. High water content
can produce saponification causes reductions of ester yield, an increment in viscosity,
difficult separation of glycerol from methyl ester and the formation of emulsion. The
mechanism of alkaline catalyst using to transfer biodiesel production was shown as
Figure 2.8. Normally, the mechanism of alkaline catalysed transesterification process
could be divided in four steps: [35]
(1) The react of the base with the alcohol, producing an alkoxide and the
protonated catalyst.
(2) Then, form a tetrahedral intermediate by nucleophilic attack of the
alkoxide at the carbonyl group of the triglyceride
(3) After that, a form of the corresponding anion of diglyceride and the
alkyl ester.
(4) Finally, the deprotonates the catalyst to form hydroxyl and reacts with
another alcohol for new cycle. Diglycerides and monoglycerides will be converted by
the same mechanism.
16
Figure 2.8 Mechanism of base catalysed transesterification process [35]
- Acid catalyst (H2SO4, HNO3, H3PO4, HCl) has been used in the
transesterification process. This catalyst suitable for oils containing high free fatty acid.
However, acid can produce a large number of salt interaction that causes of corrosion
and toxic. The mechanism of acid catalyst using to transfer biodiesel production was
shown as Figure 2.9. Firstly, the acid has protonated the oxygen on the carbonyl group
of the ester to form the carbocation (2). Then, to produces the tetrahedral intermediate
by the nucleophilic attack of the alcohol (3). After that, eliminates glycerol to form the
new ester (4) and to regenerate the catalyst H+. Diglycerides and monoglycerides will
be converted by the same mechanism. [36]
17
Figure 2.9 Mechanism of acid catalysed transesterification process [35, 36]
- Enzymatic catalyst (immobilized lipase) such as Rhizomucor miehei,
Pseudomonas cepacia, Candida rugosa, Rhizopus oryzae. This catalyst use at lower
operating temperature, no byproduct, reusability without any separation and wash.
However, it is very expensive, enzyme activity losses may occur due to waste water
and alcohol effects.
2.3 Furfural
Furfural, 2-furancarbonal, 2-furaldehyde or furfuraldehyde (C5H4O2) is a
cyclic aldehyde as shown in Figure 2.10 derived from variety agricultural byproducts
(corncobs, bagasse, oat hulls, almond hucks, cottonseed hulls, rice hulls, etc). The
furfural is an alternative non-petroleum based chemical feedstock. It is viscous,
colorless liquid that has an aromatic odor reminiscent of almonds which quickly
darkens or black color when exposed to air. [37] The physical properties of furfural was
shown in Table 2.3.
Figure 2.10 Chemical structure of furfural
18
Table 2.3 Physical properties of furfural [37]
Property
Molar mass (g/mol.) 96.08
Boiling point at 101.3 kPa (C) 161.7
Flash point, tag closed cup (C) 61.7
at 20C (g/cm3) 1.1598
Vapor density (Air = 1) 3.3
Critical pressure Pc (MPa) 5.502
Viscosity, 25C (mPa.s) 1.49
Critical temperature Tc (C) 397
Solubility, in water, wt.% (25C) 8.3
Ethyl alcohol, diethyl ether
Spectroscopic polarity (ETN) 0.426
Dielectric constant at 20C 41.9
Heat of vaporization (liquid) (kJ/mol) 42.8
Heat capacity (liquid, 20 – 100C) (Jg-1K-1) 11.74
Heat of combustion (liquid) (kJ/mol) 2344
Hf (l), (kJ/mol) -201.65
Hf (g), (kJ/mol) -151.05
Explosion limits (in air), (vol.%) 2.1 - 19.3
Surface tension at 29.9C (mN/m) 40.7
Furfural undergoes reactions typical for aldehydes like alkylation
(arylation), acetalization and acylation, aldol and condensations. Furfural is diverse
derivatives and widespread applications in the industry are given in Figure 2.11. It can
be used to make other furan chemicals, such as furoic acid. Furfural is also an important
19
chemical solvent. Of the world production of furfural 60 – 70% is converted to furfuryl
alcohol. The remaining part was used as:
Extractant for aromatics from lubricating oils
Purification solvent for C4 and C5 hydrocarbons
Reactive solvent and wetting agent
Chemical feedstock for other furan derivatives
Nematode control agent
Therefore, furfural has been suggested as a platform chemical for biofuels
and biochemicals production. [37]
Figure 2.11 Chemicals derived from furfural [37]
2.4 Catalyst
Catalysis is the process that increases the rate of a chemical reaction. The
reactions happen faster and lower activation energy. Normally, catalysts have been
divided as a homogeneous and heterogeneous catalyst. Depending on the purpose we
can select the suitable catalyst.
20
2.4.1 Homogeneous catalyst
The homogeneous catalyst is operated in the same phase where the reaction
occurs. In principle, there is no limitation on the phase to be considered, the reaction
occurs as a gaseous or liquid phase.
The great variety of homogeneous catalyst is known, ranging from
Bronsted and Lewis acids widely used in organic synthesis, metal complexes, metals
ions, organometallic complexes, organic molecules up to biocatalysts (Enzymes,
artificial enzymes, etc.) However, it is difficult to separate after reaction and corrosive
equipment. [38]
2.4.2 Heterogenous catalyst
The heterogeneous catalyst is operated in the different phases where the
reaction occurs. The catalyst usually in a solid form and the reaction occurs either in
the liquid or gaseous phase. A heterogeneous catalytic reaction affects the adsorption
of reactants from a liquid phase onto a solid surface, the surface reaction of adsorbed
and desorption of products into the liquid phase. The advanced of this catalyst is simple
to separate and recycle from the reactants and products. That is one of the main points
to show the low cost and environmental friendly. Moreover, the heterogenous catalyst
gives noncorrosive in reactor and less toxic. The solid catalysts requires a high active
surface area and small size distribution effect to the conversion and selectivity of
products. The main comparison of homogeneous and heterogenous catalyst can be
summarized in Table 2.4
Table 2.4 Comparison of homogeneous and heterogeneous catalyst [38]
Property Homogeneous Heterogeneous
Catalyst recovery Difficult and expensive Easy and cheap
Thermal stability Poor Good
Selectivity Good
Single active site
Poor
Multiple active sites
21
2.5 Carbon solid acid catalyst (CM-SO3H)
A several of solid acid catalysts are developed, including immobilized
liquid acid (e.g. HF/AlCl3), zeolite molecular sieve (e.g. H-ZSM-5), metal oxide (e.g.
A12O3), metal sulfide (e.g. CdS), heteropoly acid (e.g. H3PW12O40), natural clay (e.g.
bentonite), cation exchange resin (e.g. Nafion-H), and solid superacid (SO42-/ZrO2) etc.
However, the limitation due to restricted reaction rates and harmful side reactions,
deactivates due to sulfate, formation of carbonaceous deposits on Brønsted acid sites,
low acid site concentrations and high cost. [39] Therefore, many researchers would like
to improve the high acid capacity of the catalyst and cheap.
Currently, carbon material has been interested and developed rapidly. The
carbon material is stable and insoluble in most acidic or basic conditions as well as
organic solvents. It has been obtained by carbonization of biomass or biomass derived
products. The carbonization methods include pyrolysis, gasification, flash
carbonization, and hydrothermal carbonization, etc. Hydrothermal carbonization is a
thermochemical process obtained the physical and chemical dewatering or dehydration
under high pressure and low temperature (180 – 250C) of biomass. The chemical
dehydration affects the elimination of water molecules from hydroxyl groups. The
physical dewatering step is facilitated by the lower viscosity of water and fewer
hydrophilic functional groups at HTC pressures and temperatures. [40] The advantage
of HTC method is could convert the wet material into carbon solid with high yields
(yield product is mass ratio of product formed to initial feedstock based on dry weight)
and relatively low energy during the process were compared in Table 2.5. Hence, the
raw material used to convert carbon solid more abundant. So the hydrothermal process
has become an important technique and more popular.[40] In this research, we also
focus on preparation of the carbon solid acid catalyst combine between hydrothermal
carbonization and sulfonation methods.
Table 2.5 Comparison of reaction conditions, product yields for thermochemical
conversion processes to carbon solid. [41]
22
Process Reaction
temperature (C)
Product distribution (weight %)
Char Liquid Gas
Pyrolysis: Slow ~ 400C 35 30 35
Pyrolysis:
Intermediate ~ 500C 20 50 30
Pyrolysis: Fast ~ 500C 12 75 13
Gasification ~ 800C 10 5 85
HTC 180 – 250C 50 - 80 5 – 20% 2 - 5
CM-SO3H is the carbonaceous solid sulfonic acid functionalized was
shown in Figure 2.12, one of the interest catalyst support because it can easily to
synthesized and controled acid capacity, mean size distribution, also pore structure. The
structure of carbon solid acid catalyst from biomass derived is often amorphous and
owns aromatic structure, contain of -SO3H, -OH and -COOH groups. Inside that -SO3H
groups are considered as the key active acidic site, the existence of -OH and -COOH
groups would provide hydrophilic reactants accessing to the -SO3H groups so it would
be in favor of effective catalytic performance. [39] CM-SO3H is a strong acid catalyst,
stability, and low cost.
23
Figure 2.12 Formation of CM-SO3H structure
2.6 Literature reviews
Recently, the renewable resource has been interested in solve the scarcity
of feedstock from fossil and environmental issues. Biodiesel from waste cooking oil
and furfural production from xylose have received more and more attention for their
potential substitute. However, the problem from synthesis the biodiesel and furfural
production such as high use cost, low product yields due to the catalyst (low acidity,
toxic, corrosive, the amount of catalyst, etc), also a high temperature, long time.
Therefore, many researcher were developed with this problem.
Biodiesel production
Vyas et al., [42] studied synthesis of biodiesel from Jatropha oil and
methanol using homogeneous alkali catalyst (KOH) at reaction temperature 50 – 70C
for 1.5 h and stirred at 700 – 750 rpm. Product mix was allowed in a separating funnel
24
for 8 h after completion of reaction. The molar ratio 1:3 of the Jatropha oil to methanol.
The results show that the yield of the biodiesel was 86.0 %.
Vicente et al., [43] studied synthesis of biodiesel from Sunflower oil and
methanol using different basic catalysts (sodium methoxide, potassium methoxide,
sodium hydroxide and potassium hydroxide). All the experiments were carried out
under the same reaction conditions at 65C for 4 h, the molar ratio 1:6 of Sunflower oil
to methanol, catalyst loading 1.0 wt.% and stirred at 600 rpm. The results show that the
high yield of the biodiesel using NaOH, KOH, CH3KO, CH3NaO were 86.33%,
91.67%, 98.33%, 99.17%, respectively.
Wang et al., [44] studied synthesis of biodiesel from waste cooking oil and
methanol via two-step catalyzed process, which has large amounts of acid value (75.92
0.036 mg KOH/g). In the first step was esterified the free fatty acids of WCO with
methanol in the presence ferric sulfate (Fe2(SO4)3) at 95C for 4 h, the molar ratio 1:10
of WCO to methanol, catalyst loading 2.0 wt.%. The second step, the triglycerides
(TGs) in WCO were transesterified with methanol using KOH catalyst at 65C for 1 h,
the molar ratio 1:6 of WCO to methanol. The results show that the conversion of Free
Fatty Acid (FFA) and the yield of biodiesel were 97.22% and 97.02%, respectively.
Su, Chia-Hung [45] studied synthesis of biodiesel from Soybean oil and
methanol using several homogeneous acid catalysts (HNO3, H2SO4, HCl). There is only
HCl could be recovered and reused catalyst because it can be completely retained in the
separated methanol phase. The reaction condition of biodiesel production with HCl
catalyst: reaction temperature 76.67C for 103.57 min. The molar ratio 1:7.92 of FFA
to methanol, catalyst concentration 0.54M. The results show that the conversion of FFA
was 98.16%. The catalyst could be reused at least five times and the conversion was
97.0%.
The application of homogeneous catalysts was successfully for biodiesel
production due to low reaction temperature, low cost and high yield. However, many
disadvantaged such as toxicity, corrosive, could not recycle and produce the
25
saponification. Hence, a heterogenous catalyst has been interesting with many
researchers for biodiesel production.
Sirisomboonchai et al., [46] studied synthesis of biodiesel from waste
cooking oil and methanol using calcined scallop shell as a catalyst. The catalyst loading
5.0 wt.%, the molar ratio of WCO to methanol was (1: 3, 1:6, 1:12) and stirred at 500
rpm. The results show that the FAME yield over 86.0% at 65C for 2 h was obtained
in the presence of small amount of water. The CSS catalyst was reused for 4 times as
FAME yield decreased 20% due to the formation of Ca-glyceroxide on its surface.
Maneerung et al., [47] studied synthesis of biodiesel from waste cooking
oil and methanol using CaO catalyst prepared from chicken manure. The optimum
reaction conditions were reaction temperature at 65°C for 3 h, the molar ratio 1:15 of
oil to methanol, the catalyst loading 7.5 wt.% and stirred at 1400 rpm. The results show
that the obtained CaO catalyst presented high catalytic performance biodiesel
production up to 90.0% FAME yield was achieved.
Vieira et al., [48] studied synthesis of biodiesel from Oleic acid and
methanol using heterogeneous catalyst (Lanthanum (La3+) and HZSM-5 based
catalysts) at 100C for 1 – 7 h, the catalyst loading 10.0 wt.%. The mass ratio of oleic
acid to methanol were 1:5 and 1:20 for (lanthanum oxide – LO, Sulfated lanthanum –
SLO, SLO/HZSM-5) and HZSM-5, respectively. The results show that the conversion
oleic acid were 67.0% an 96.0% for LO and SLO, respectively. And for HZSM-5 and
SLO/HZSM-5 were 80.0% and 100%, respectively. All of there catalysts deactivated
after the first use, but the deactivation of SLO/HZSM-5 was smaller.
Karnjanakom et al., [49] studied synthesis of biodiesel from Hevea
brasiliensis oil (para rubber seed oil) and methanol using SO3H-MCM-41 catalyst. The
optimum reaction conditions were reaction temperature at 153°C for 2 h, the catalyst
loading 5.06 wt.%, 0.266 of MPMDS molar composition and stirred at 500 rpm. The
results show that the yield of biodiesel production was 95.5%. This catalyst could be
reused up to 4 times without significant loss yield of product.
26
Talebian-Kiakalaieh et al., [50] studied synthesis of biodiesel from waste
cooking oil and methanol using heterogeneous heteropoly acid (HPA) catalyst. The
optimum reaction conditions were reaction temperature at 65C for 14 h, the molar ratio
1:70 of oil to methanol and the catalyst loading 10 wt.%. The results show that highest
conversion was 88.6%. The response surface methodology (R2 = 0.9987) and the
reaction followed first-order kinetics with the calculated activation energy, Ea = 53.99
kJ/mol.
Shu et al., [51] studied synthesis of biodiesel from cottonseed oil and
methanol using a carbon-based solid acid catalyst at reaction temperature 260C for 3
h. The resulting showed the conversion of cottonseed oil 89.93% was obtained when
the methanol/cottonseed oil molar ratio was 18.2 and catalyst loading 0.20 wt% of oil.
The asphalt-based catalyst shows higher activity for the production of biodiesel, which
was resulted by high acid site density, its loose irregular network and providing large
pores.
Shu et al., [52] studied synthesis of biodiesel from waste vegetable oil with
large amount of free fatty acid using a carbon-based solid acid catalyst at temperature
range 180 – 220C range for 4.5 h. The results show conversion of triglyceride and FFA
reached 80.5 wt.% and 94.8 wt.%, respectively using a 16.8 molar ratio of methanol to
oil and 0.2 wt% of catalyst loading.
Li et al., [53] studied synthesis of biodiesel from waste cooking oil and
methanol using a heterogeneous catalyst from pyrolyzed rice husk. A solid acid catalyst
was prepared by sulfonating pyrolyzed rice husk with concentrated sulfuric acid. The
result show that the conversion of free fatty acid (FFA) reached 98.17% after 3 h at
110C, and the fatty acid methyl ester (FAME) yield reached 87.57% at 110C after
15h.
Dawodu et al., [54] studied effective conversion of non-edible oil with
sulfonated carbon catalyst. At the optimized conditions, high conversion (99%) was
achieved. Increasing the temperature also increased FAME yield and FAME yield
27
finally reached 99.0% over the two catalytic systems at temperature of 180C for 1 – 5
h at ratio of FFA to methanol 1:30 and the range of 1.5–7.5 wt.% of catalyst to oil.
Fu et al., [55] synthesized the carbon solid acid catalyst from β-cyclodextrin
for biodiesel production. This catalyts was prepared by incomplete hydrothermal
carbonization of β-cyclodextrin and sulfonation with sulfuric acid (98.0%). The highest
FAME yield of high FFA (55.2%) containing oils reached 79.98 % after 12 h, catalyst
loading 5.0 wt.% and the molar ratio 1:10 of oleic acid to methanol. The catalyst can
be regenerated within 6 cycles after washed with methanol or sulfuric acid.
Ngaosuwan et al., [56] studied synthesis of biodiesel from caprylic acid
(HCp) and methanol using sulfonated carbon-based catalyst derived from coffee
residue. The catalyst was synthesized under a carbonization temperature of 600C for
4 h and sulfonation temperature of 200C for 18 h. The reaction conditions were 60C
for 4 h, the molar ratio 1:3 of caprylic acid to methanol, the catalyst loading 5 wt.% and
stirred at 600 rpm. The highest conversion of caprylic acid was 71.5%. This catalyst are
not comparable on a mass to the homogeneous H2SO4 catalyst. However, it is in the
ease of handling, recyclability, and being environmentally friendly.
Furfural production
Long Li et al., [57] investigated as a water-tolerant tantalum based catalyst
for the dehydration of D-xylose to furfural by using a biphasic system containing water
and 1-butanol. The highest furfural yield was 59.0%, the conversion of D-xylose was
96.0% at 180C for 3 h in the continuous process.
Rong et al., [58] studied the dehydration of xylose to furfural at atmospheric
pressure using sulfuric acid and inorganic salts (NaCl or FeCl3) and a biphasic
containing toluene and water. The results show that the highest yield of furfural was
83.0% under reaction conditions: 10 wt.% H2SO4, 10wt.% of the xylose to the mixture
(150 mL of toluene and 10 mL of water), 2.4 g NaCl and heating for 5 h. FeCl3 was
shown to be more efficient than NaCl.
28
Zhang et al., [59] studied the dehydration of xylan, D-xylose and
lignocellulosic biomass into furfural using AlCl3 as catalyst in ionic liquid (1-butyl-3-
methylimidazolium chloride). The highest yield of furfural was 84.8% at 170C for 10
s. The conversion of D-xylose and untreated lignocellulosic biomass was also
investigated. The furfural yield of corncob, grass and pine wood were in the range of
16.0–33.0%.
Choudhary et al., [60] investigated the conversion of xylose to furfural
using Lewis (CrCl3) and Brønsted acid (HCl) catalysts in water were shown as Figure
2.13. The highest furfural yield and conversion of xylose were 76.3% and 95.8%,
respectively under following the reaction conditions: initial xylose 1.0 wt. % in
biphasic systems (2.0 mL of aqueous solution), toluene (2.0 mL) as the extracting
solvent, at reaction temperature 140C for 2 h and mixture of CrCl3 (6.0 mM), HCl
(0.1 M). Using the combination of Lewis and Brønsted acids, a furfural yield (39.0%)
higher than using HCl alone (29.0%) at reaction temperature (∼145C) in a single
aqueous phase.
Figure 2.13 The overall paths to produce furfural from xylose in the presence of a
single bronsted acid catalyst and of both lewis and bronsted acid catalysts [60]
Sádaba et al., [61] prepared the vanadium phosphates (VPO) as catalysts
for xylose dehydration. The orthorhombic vanadyl pyrophosphate catalyst (VO)2P2O7
was prepared by calcination of VOHPO4.5H2O at 550C for 2 h. The results show that
the yield of furfural was 56% at 170C for 6h, catalyst loading 1.5 wt.% (the
29
concentration of (VO)2P2O7 as low as 5.0 mM) and 1.0 mL water–toluene solvent
mixture (3:7 volume ratio).
Hua et al., [62] prepared the reaction kinetics of xylose dehydration to
furfural using Organosulfonic acid-functionalized mesoporous silica (SO3H-SBA-15).
The results show that the best of furfural yield was 75.0% at 200C for 3 h in the mixture
(ethyl butyrate (17.5 mL) and water (7.5 mL)). The reaction kinetics of xylose
dehydration to furfural was investigated and the activation energy was 68.5 kJ/mol, the
reaction order was 0.50.
Zhang et al., [63] studied conversion of D-xylose to furfural with
mesoporous molecular sieve MCM-41 as catalyst and 1-butanol as the extraction
solvent. At the optimized conditions, the volume ratio 1.5 of 1-butanol to water,
reaction temperature at 170C for 3 h, furfural yield and xylose conversion were
obtained more than 96.85% and 44.05%, respectively.
Doiseau et al., [64] studied effect between solid acid catalysts and
concentrated carboxylic acids solutions for efficient furfural production from xylose.
The presence of solid acid catalysts in aqueous acetic acid solution had influence in the
transformation of xylose to furfural. Furfural yield and furfural selectivity of this system
were higher than the catalytic performances obtained in pure water at 150C.
Kaiprommarat et al., [65] investigated the sulfonic acid-functionalized
MCM-41 (SO3H-MCM-41) and methyl propyl sulfonic acid-functionalized MCM-41
(MPrSO3H-MCM-41) catalysts for xylose dehydration to furfural. The MPrSO3H-
MCM-41 catalyst was improved the furfural product to obtain a high turn-over
frequency. The furfural yield, furfural selectivity and xylose conversion were 93.0%,
98.0% and 95.0%, respectively at the optimum conditions 155C for 2 h, biphasic
mixture contains water and toluene. This research suggested that the pore diameter of
catalyst (3 – 6 nm) could provide a furfural selectivity higher than 93.0%.
Zhang et al., [66] synthesized carbon solid acid catalyst by sulfonation of
carbonaceous material which was prepared from sucrose using 4-BDS as a sulfonating
agent. The mixture of xylose or corn stalk (0.4 g), carbon catalyst (0.2 g), -
30
valerolactone (16.5 ml) were put into the reactor. The highest furfural yields derived
from xylose was 78.5% at 170C for 30 min and corn stalk in this study was 60.6% at
200C for 200 min. This catalyst could be reused for 5 times without the loss of furfural
yields.
Khatri et al., [67] studied a sulfonated polymer impregnated carbon
composite as a solid acid catalyst for dehydration of xylose to furfural. In this research,
the cabon solid acid catalyst (C-SO3H) and polymer impregnated carbon solid acid
catalyst (P-C-SO3H) were prepared by combination of pyrolyzed and sulfonated
method. The optimun reaction condition: 150C for 3 h, 0.50 g xylose, and 0.10 g
catalyst and 25.0 mL DMSO was used as a extraction solvent. The P–C–SO3H catalyst
showed higher conversion (98.0%) and selective (100%) than C–SO3H (xylose
conversion: 45.0%, furfural selectivity: 98.0%). P-C-SO3H was easily recovered and
reused without significant loss in its activity.
For these reason, CM-SO3H catalyst would be prepared by hydrothermal
carbonization from xylose and sulfonation method and applied for biodiesel, furfural
production.
31
CHAPTER 3
RESEARCH METHODOLOGY
3.1 Materials
All chemicals and equipments used in this research were shown in Table
3.1 and Table 3.2, respectively.
3.1.1 Chemicals
Table 3.1 List of the chemicals used in this research
Chemicals Manufacturer Country
Acetone, Comercial grade RCI Labscan USA
Acetonitrile, HPLC grade RCI Labscan USA
Commercial grade xylose N/A Thailand
D-Xylose Sigma-Aldrich USA
Heptane, AR grade QReC New Zealand
Methanol, AR grade QReC New Zealand
Methanol, HPLC grade RCI Labscan USA
Methyl heptadecanote, AR grade Fluka USA
Potassium hydroxide Ajax Finechem Australia
Toluene, AR grade RCI Labscan USA
Sodium carbonate (Na2CO3) Ajax Finechem Australia
Sodium sulfate anhydrous (Na2SO4) Ajax Finechem Australia
Sulfuric acid, 98% QReC New Zealand
Mixed Waste cooking oil (WCO) TU Canteen Thailand
32
3.1.2 Equipments
Table 3.2 List of the instrument used in this research
Instrument Brand
Autoclave reactor, 50ml Parr, USA
Autoclave reactor, 400 ml Amar Equipment, India
Centrifugation Labquip, England.
Fourier Transform Infrared spectroscopy
(FT-IR)
Perkin Elmer, Spectrum 100 FT-IR
spectrometer
Gas Chromatography-Flame Ionization
Detector (GC-FID)
Shimadzu, Japan, GC-17A
Gas Chromatography-Mass Spectrometry
(GC-MS)
Shimadzu, Japan, GCMS-QP
2010
High Performance Liquid Chromatograph
(HPLC)
Shimadzu, Japan, LC-20AT
(pump), SPD-20A (UV dectector)
N2 sorption Quantachrome, USA
Oven Memmert UF 110
Scanning Electron Microscope (SEM) JEOL, Japan, JSM-6510LV
Temperature Programed Desorption
of ammonia (NH3-TPD)
Thermo Electron Instrument,
USA, TPD/R/O1100
X-ray photoelectron Spectroscopy (XPS) ULVAC-PHI, Japan, PHI 500
VersaProbe II
3.2 Methods
3.2.1 Preparation of carbon solid acid catalyst (CM-SO3H)
The carbon solid acid catalyst was prepared by sequential
hydrothermal carbonization and sulfonation of xylose.
33
First of all, 20.0 mL of 50 wt.% xylose solution was transferred to 50.0
mL an autoclave, heated to temperature of 190C and maintained at this temperature
for 24 h. The resulting solid product was recovered by centrifugation at 4000 rpm for
15 minutes and washed with DI water. Then, the carbon solid was dried at 90C for 4h.
For sulfonation, the mixture of carbon 1.0 g and 20.0 mL H2SO4 (98%)
was placed in an autoclave and heated at 150C for 15 h. Then, the carbon solid catalyst
was collected by centrifugation at 5000 rpm for 15 min and washed repeatedly with
abundant DI water until pH 7.0. Finally, the product was dried at 90C for 4 h. The
synthesis of CM-SO3H catalyst could be summarized in Figure 3.1.
In addition, a porous carbon solid acid catalyst (P-C-SO3H) was
derived by activation of carbon microsphere with potassium hydroxide to improve their
porous properties. The mixture of 2.0 g of carbon microsphere and 8.0 g of KOH (25
wt.%) were transferred to crucible, heated at 700C for 2 h with 3C/min. Then, the
carbon solid was collected by vacuum filtration and washed with abundant DI water
until pH 7.0. Next, the porous carbon was dried at 90C for 4 h. Finally, the P-C-
SO3H was sulfonated by same method with CM-SO3H.
Figure 3.1 Schematic diagram of synthesized CM-SO3H catalyst
34
3.2.2 Characterization of catalyst
3.2.2.1 Study the morphology of catalyst
The surface morphology and particle size distribution of hydrothermal
carbon, CM-SO3H, and reused CM-SO3H were determined by a scanning electron
microscope (SEM, JEOL JSM-6510LV). All of sample were dried at 70C, overnight
for removed moisture and then put up on a SEM stub, coated with thin layer of gold
under vacuum and observed at 20 kV.
3.2.2.2 Study the textural analysis
The porous structure and surface area of hydrothermal carbon, CM-SO3H,
and reused CM-SO3H were analyzed by N2-sorption using an Autosorb-iQ instrument
(USA). The surface area was identified from Brunauer Emmett Teller (BET) equation
using standard data from isotherm on nonporous carbon and the pore size, pore volume
was identified from Barrett Joiner Halender model (BJH).
3.2.2.3 Study the functional group
The presence of functional groups on the hydrothermal carbon, CM-SO3H,
and reused CM-SO3H surface were characterized by Attenuated Total Reflectance
Fourier transform infrared spectroscopy (ATR-FTIR). All of sample were dried at
70C, overnight for removed moisture and then put onto a sample holder. After that,
the infrared spectra were recorded wavelength number from 4000 to 500 cm-1 with 32
scans.
The elemental composition and functional group (-SO3H) were
characterized by X-ray photoelectron spectroscopy (XPS) using Al-Kα radiation (hν =
117.40 eV).
3.2.2.4 Study the properties of acid sites
The acid strength of catalyst was investigated by Temperature Programed
Desorption of ammonia (NH3-TPD) using Thermo Electron Instrument, TPD/R/O1100.
35
And the amount of –SO3H and –COOH groups on the catalyst surface was calculated
by titration method and used phenolphthalein as an indicator. The amount of acid
groups on catalyst surface was determinized by amount of spent NaOH 0.1N.
3.2.3 Catalytic activity in biodiesel production from waste cooking oil
3.2.3.1 Biodiesel production
Waste cooking oil (WCO) was provided by a restaurant in Thailand used
as the raw material for the production of biodiesel. The reaction was carried out by two
steps process for overcoming the chemical equilibrium. Each step was done as this
procedure. The mixture of WCO, methanol and CM-SO3H was transferred to 400 mL
an autoclave (Amar Equipments, India) and heated to desired temperature and time
under stirring rate at 500 rpm. The effect of reaction factors were investigated such as:
weight percent of catalyst/oil (5.0 to 15.0 wt.%), molar ratio of methanol/oil (5.64:1,
9.35:1, 14.87:1), reaction temperature (90 - 150°C) and reaction time (0.5 - 6.0 h). After
the reaction, the reactor was cooled down and then the mixture of the product was
centrifuged at 5000 rpm for 15 min to separate the catalyst. Next, the product was
poured into a separatory funnel and allowed to phase separate for 8 h. After separation,
the above layer was washed with hot deionized water until pH value in the aqueous
phase reached 7.0. After that, the methyl ester phase, upper phase, was dried at 105°C
for 45 min for remove remained of methanol and water. The fatty acid methyl ester
(FAME) yield was analyzed by gas chromatography follow standard method EN 14103.
The second step biodiesel production was carried out by repeating the first step with
biodiesel fraction of the first step.
3.2.3.2 FAME analysis
The fatty acid methyl ester (FAME) yield was determined by gas
chromatography (Shimadzu GC-17A, flame ionization detector). The capillary column
was DB-WAX (30.0 m length, 0.25 mm internal diameter and 0.25 mm film thickness).
The column temperature were shown in Table 3.3. And 1.0 µL of prepared sample
would be injected at GC injection port by using a syringe for GC. Standard sample was
36
used to calculate the FAME yield by integration of the peak areas using internal
standard method by Equation 3.1.
Table 3.3 The program of column temperature
Column temperature program
Initial temperature: 150C hold at 5 min
Rate 1: 3C/min to 190C hold at 5 min
Rate 2: 3C/min to 220C hold at 10 min
EI EI EIyield
EI
( A) A C x V%FAME x x100
A m
(3.1)
A is the total peak area of methyl ester peak from C14 to C24:1
AEI is the peak area of internal standard (methyl heptadecanoate, C17)
CEI is the concentration of the internal standard (mg/mL)
VEI is the volume of the internal standard solution (mL)
m is the mass of the sample (mg)
3.2.3.3 Catalyst reusability
For the catalyst reusability, the used catalyst was washed with acetone and
dried at 70C, overnight. The catalytic activity was then tested under the same as
previous procedure done by fresh catalyst.
3.2.4 Catalytic activity in furfural production via xylose dehydration
3.2.4.1 Dehydration of xylose
The xylose dehydration was carried out in an 400 mL autoclave (Amar
Equipments, India) containing the mixture of xylose solution (0.50 g xylose dissolved
with 12.5 mL DI water), 12.5 mL toluene and CM-SO3H catalysts. The reactor was
heated to desired reaction temperature (120, 140, 155 and 170°C) at stirring rate of 450
rpm for suspected reaction time (1–3 h). After the reaction finish, the mixture was
cooled down, the product was washed from the reactor by 12.5 mL DI water and 12.5
37
mL toluene. Then filtered to separate the catalyst and washed product with 25.0 mL DI
water and 25.0 mL toluene to obtain the liquid product with two layers in separatory
funnel: toluene phase and aqueous phase. The upper layer was separated and dried over
anhydrous sodium sulfate. Two liquid phases were filtered before analysis. Then,
furfural was determined by high-performance liquid chromatography (HPLC)
connected with UV detector and Agilent Eclipse XDB-C18 column. [59] Xylose
content was determined by gas chromatography-mass spectroscopy with headspace
technique using HP-5 which was reported by Kaiprommarat, et.al and Li, et.al. [65, 68]
3.2.4.2 Product analysis
The furfural yield both 2 phases (toluene and aqueous phase) were
analyzed by high-performance liquid chromatography (Shimadzu, Japan) with Agilent
Eclipse XDB-C18 column (4.6 mm ID x 250 mm), the mobile phase at flow 1.0 mL/min
with volume ratio of acetonitrile/DI water (v/v) is 15/85, and 20.0 µL of sample would
be injected. The xylose conversion was determinized by headspace gas
chromatography-mass spectrometry (GCMS-QP2010, Shimadzu, Japan) with HP-5
column (0.25 mm ID, 30 m length, 0.25 mm film thickness). The injection temperature
at 105°C. The column oven temperature was started at 70°C and heat up to 90°C with
2°C/min. [65]
The furfural yield, furfural selectivity and xylose conversion were
calculated by equation 3.2, 3.3 and 3.4, respectively. [65, 69]
Moles of furfural producedFurfural yield = x100
Moles of starting xylose(3.2)
Moles of furfural producedFurfural selectivity = x100
Moles of xylose reacted(3.3)
Moles of xylose reactedXylose conversion = x100
Moles of starting xylose(3.4)
38
CHAPTER 4
RESULTS AND DISCUSSION
4.1 Characterization of the carbon catalyst
Carbon microsphere was prepared by hydrothermal carbonization of xylose
and functionalized with sulfonic acid. This catalyst was designated as CM-SO3H
catalyst. In addition, a porous carbon solid acid catalyst (P-C-SO3H) was synthesized
by activation of carbon microsphere with potassium hydroxide and functionalized with
sulfuric acid.
4.1.1 N2 sorption analysis
The textural properties of carbon microsphere, CM-SO3H and P-C-SO3H
were studied by nitrogen absorption and desorption which the isotherms are presented
in Figure 4.1. The isotherm of both carbon microsphere and CM-SO3H conformed to
type II isotherm with a hysteresis loops of H3 to imply non-porous structures and
according to slit-shaped pores agglomerated due to changing of particle sizes after
functionalized from 0.8 m to 2.7 m. The isotherm of P-C-SO3H was the type IV
isotherm with a hysteresis loops of H4, which refers to a mesoporous strucutre with
narrow slit shape pore.
39
Figure 4.1. Nitrogen sorption isotherms of (a) carbon microsphere (CM): overlay 40
units; (b) solid acid catalyst (CM-SO3H): overlay 80 units and (c) porous carbon solid
acid catalyst (P-C-SO3H)
The pore size distribution and textural properties such as BET surface area,
BJH pore size, and pore volume are presented in Figure 4.2 and Table 4.1, respectively.
The surface areas were calculated with the Brunauer–Emmett–Teller (BET) equation
using standard data for N2 adsorption on nonporous carbon. The carbon microsphere
has a high surface area (SBET = 95.5 m2/g) which was higher than the sulfonated carbon
microsphere (SBET = 86.3 m2/g) and porous carbon solid acid catalyst (SBET = 74.4 m2/g)
due to agglomeration of carbon particle after sulfonation. In addition, pore size of CM-
SO3H was increased from 3.4 nm to 6.6 nm that effect from the formation of SO3H
group on carbon microsphere surface. Because, most of the pores are formed by the
agglomeration of particles. Therefore, the uniform particle size caused the uniformity
of the pore sizes. Moreover, the larger particles formed larger interparticle pores. [29,
70]. This results could be suggested by the particle size distribution of hydrothermal
carbon and CM-SO3H, which could be observed by SEM.
0
40
80
120
160
200
240
280
320
0 0.2 0.4 0.6 0.8 1
Volu
me
@ S
TP
[cc
/g]
Relative Pressure (P/P0)
(a)
(b)
(c)
(a)
(b)
(c)
40
Figure 4.2 Pore size distribution of (a) carbon microsphere; (b) carbon solid acid
catalyst (CM-SO3H) and (c) porous carbon solid acid catalyst (P-C-SO3H)
Table 4.1 Textural properties and acidity of carbon microspheres, and catalysts.
BET surface
area (m2/g)
Pore size
(nm)
Pore volume
(cc/g)
Acidity
(NH3-TPD)
Carbon microsphere 95.5 3.4 0.094 0.049
CM-SO3H 86.3 6.6 0.09 1.38
P-C-SO3H 74.4 3.8 0.54 1.28
3rd reused CM-SO3H 10.4 3.4 0.01 0.59
4.1.2 The morphology of catalyst
The morphology of carbon microsphere and carbon solid acid catalyst
(CM-SO3H), are shown in Figure 4.3. Both carbon microsphere, CM-SO3H were
spherical shape with average particle diameter as 0.8 m, 2.7 m, respectively.
According to SEM micrograph, carbon microsphere presented uniform particle size
whereas, the CM-SO3H particle was wide distribution because adding sulfuric acid to
the carbon microsphere not only functionalized the sulfonic group (-SO3H) on carbon
microsphere but also the presence of sulfuric acid in sulfonation step catalyzed
dehydration of xylose to furan compounds which were important intermediates for
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
1 10 100
dV
(lo
gd
) (c
c/g)
Pore diameter (nm)
(b)
(a)
(c)
41
carbonization. However, the excess of furan compounds promoted fast polymerization
rate to grow carbon particle without uniformity. Qi. Xinhua et al. [70] reported that
catalyst growth by swell, diffusion and linkage from the –SO3H group to the surface.
Figure 4.3 SEM microphotograph of (a) carbon microsphere; (b) carbon solid acid
catalyst (CM-SO3H).
4.1.3 The properties of acid sites
The acid properties including acidity and acid strength of CM-SO3H and P-
C-SO3H catalyst were investigated by NH3-TPD analysis. The NH3-TPD profile of
catalysts presented two acid sites as shown in Figure 4.4 and Table 4.1. The low and
high desorption temperature corresponded to weak and strong acid sites, respectively
[51, 52]. The major peak as weak acid site was observed at the temperature 170°C to
represent desorption of ammonia from carboxylic group. The carboxylic was derived
from oxidation of aldehyde functional group containg in aldose sugar under
hydrothermally condition. The second peak at temperature 250°C was generated by
42
ammonia desorption from sulfonic acid site. The total acidity of CM-SO3H and P-C-
SO3H catalyst were 1.38 mmol/g and 1.28 mmol/g, respectively. According to NH3-
TPD graph of acid sites, the carboxylic group and sulfonic group were different between
two catalysts. Because, after activation of carbon microsphere with potassium
hydroxide decarbonylation removed C=O to decrease number of carboxylic acid.
Figure 4.4 NH3-TPD profile of (a) carbon solid acid catalyst (CM-SO3H) and (b)
porous carbon solid acid catalyts (P-C-SO3H)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 100 200 300 400
Sig
nal
(mV
)
Temperature (C)
(a)
-COOH
-SO3H
0 100 200 300 400
Sig
na
l (m
V)
Temperature (C)
-COOH
-SO3H
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 100 200 300 400
Sig
na
l (m
V)
Temperature (C)
(a)-COOH
-SO3H
(b)
43
4.1.4 The functional group
The presence of functional group on the surface of carbon microsphere,
CM-SO3H and P-C-SO3H were identified by FTIR and XPS spectral, as shown in
Figure 4.5 and Figure 4.6, respectively. Both hydrothermal carbon, sulfonated carbon
microsphere and porous carbon solid acid catalyst displayed major characteristic peaks
of hydrothemally carbon including C=O group (carbonyl, quinone, ester, or carboxyl)
at 1701 cm-1, C=C group (alkenyl) at 1602 cm-1, C–O group (ether, hydroxyl or ester)
at 1020 cm-1, and C-H group (aromatic) at 875–750 cm-1 [25, 71]. After sulfonation,
the distinct absorption peak at 1032 cm-1 and weak absorption peak at 1171 cm-1 were
appeared according to O=S=O and -SO3H, respectively. [71] In the region of 3390 cm-
1, the broad peak of a –OH group, which could be in the form of –SO2OH or –COOH,
was also appeared. [72] These results confirm the presence of the -SO3H group on the
CM-SO3H and P-C-SO3H catalyst surface. Much stronger absorption peaks around
1032 cm-1 and 1171 cm-1 in P–C–SO3H to compared with CM–SO3H are assigned
higher amount of S=O and –SO3H, respectively, which clearly suggested the higher
loading of the sulfonic acid functional group in the P–C–SO3H than CM–SO3H was
obtained.
44
Figure 4.5 FTIR spectral of (a) carbon microsphere, (b) CM-SO3H and (c) P-C-SO3H
In addition, the XPS spectra of CM-SO3H showed peaks of S 2p, C 1s, and
O 1s. The peak of S 2p at 169 eV corresponds to sulfonic acid (-SO3H), to confirm the
existence of sulfonic acid groups (-SO3H) on the carbon microsphere surface. The C 1s
peak at 285 eV, 286 eV, and 289.3 eV were corresponds to C-C bonding, C-O, and –
COO functional groups, respectively. [73, 74] Therefore, the CM-SO3H exhibited two
different acid sites for the catalysis of biodiesel production, carboxylic acid, and
sulfonic acid.
5001000150020002500300035004000
Tra
nsm
itta
nce
(a
.u)
Wavenumber (cm-1)
C-O
stretching
C-H
aromatic
O-H
C=O C=C
-SO3H
S=O
(a)
(b)
(c)
O-H
45
Figure 4.6 XPS spectra of CM-SO3H
4.2 Catalytic activity in biodiesel production from waste cooking oil
The chemical composition and physicochemical properties of waste
cooking oil are shown in Table 4.2.
Table 4.2 The chemical composition and physicochemical properties of waste cooking
oil
Properties WCO Biodiesel**
Heptanal (C7H14O) (%) 11.85 N/A
Palmitic acid (C16:0) (%) 22.68 N/A
Oleic acid (C18:1) (%) 19.12 N/A
Nonadecylic acid (C19:0) (%) 46.35 N/A
Mean molecular wt. (g mol-1)* 787.36 N/A
Acid value (mg KOH g−1) (ASTM-D664) 2.7 0.72
0
3000
6000
9000
12000
15000
0 100 200 300 400 500 600
Ch
emic
al
Sta
te
Binding Energy (eV)
C 1sC-O
C-C
-COO
-SO3H
O 1s
S 2p
46
% FFA 1.54 0.36
Kinematic viscosity (at 40˚C cSt) (ASTM-D445) 60.10 6.41
Water and sediment (v/v %) (ASTM-D2709) 0.03 0.005
Flash point (˚C) (ASTM-D92) >370 167
Pour point (˚C) (ASTM-D97) -22 -7.5
Ash content (%) (ASTM-D482-13) 0.16 0.057
Remark:
(*) Mean molecular weight (mol/g) = 3 x (Percent of fatty acid x molar
mass of fatty acid).
(**) The biodiesel production was prepared at 110C for 2 h, ratio of
oil/methanol is 1:9.35 and 10 wt.% of catalyst loading.
4.2.1 Effect of reaction temperature
The effect of reaction temperature on the biodiesel yield was investigated
at four different temperatures, as shown in Figure 4.7. The effect of reaction
temperature performed endothermic reaction behavior that increasing FAME yield was
obtained by raising reaction temperature. However, the increasing reaction temperature
over boiling point of methanol decreased the FAME yield owning to the evaporation of
methanol to reduce the stoichiometric ratio between oil and methanol. In addition, less
acitve site in catalyst would be obtained because at high reaction temperature –SO3H
functional group would be decomposed [50, 75]. The highest FAME yield was 82.5
wt.% at 110°C for 6 h.
47
Figure 4.7 FAME yield with different reaction temperatures at reaction time 6 h,
molar ratio of oil/methanol 1:9.35, and catalyst loading 10 wt.%.
4.2.2 Effect of reaction time
The effect of reaction time on FAME yield was studied at 110C, it can be
seen that the reaction reached to equilibrium within 2 h to obtain highest FAME yield
of 89.6% as shown in Figure 4.8. The increasing of biodiesel yield was derived by
increasing reaction time. Moreover, the longer reaction time (over than 2 h) did not
significantly provide higher FAME yield due to deactivated the acid site (–SO3H)
which was binding with the polar molecules from reaction such as methanol and water
[76].
#REF!
#REF!
0
20
40
60
80
100
90 110 130 150
68.04
82.5
72.469.7
%Y
ield
of
bio
die
sel
Reaction temperature (C)
First step
Second step
48
Figure 4.8 FAME yield with different reaction times at reaction temperature 110C,
molar ratio of oil/methanol 1:9.35, and catalyst loading 10 wt.%.
4.2.3 Effect of catalyst loading
The amount of catalyst affected to the conversion of waste cooking oil as
shown in Figure 4.9. The different catalyst loading including 5 wt.%, 10 wt.%, 15 wt.%
were investigated. When the increasing of catalyst loading from 5 to 15 wt.% performed
increasing the percentage of FAME yield. However, high catalyst loading induced non-
uniform mixing and increased the viscosity of the reaction mixture causing a reduction
in the efficiency of reactant transport to obtain lower the biodiesel yields [50].
Moreover, in the case of less catalyst loading, the acid capacity of the catalyst was not
enough for active in the interface of two-phases (methanol and oil) to convert oil to
FAME [50, 51, 72]. Therefore, 10 wt.% loading of the carbon solid acid catalyst was
selected as the optimal amount.
#REF!
#REF!
0
20
40
60
80
100
0.5 1 2 3 6
64.96
72.95
89.6 88.182.5
%Y
ield
of
bio
die
sel
Reaction time (h)
First step
Second step
49
Figure 4.9 FAME yields with different catalyst loading at reaction temperature
110 C for 2 h; molar ratio of oil/methanol is 1:9.35.
4.2.4 Reusability
The stability of the sulfonated carbon microsphere catalyst was also
investigated. The spent of catalyst was tested reusability up to 3rd cycles at the optimum
condition (reaction temperature 110C for 2 h, molar ratio of oil/methanol is 1:9.35, 10
wt.% of catalyst loading). The reusability of catalyst is shown in Figure 4.10. The
biodiesel yield was decreased by 21% after 3 cycles. The reduction of the catalytic
activity was caused by the deactivation of catalyst within reaction process. [54, 72] The
acidity of spent catalyst after 3 cycles of reuse was 0.59 mmol/g. The characterizations
of spent catalyst were investigated by N2 sorption, SEM micrograph, and NH3-TPD as
shown in Figure 4.11, 4.12 and 4.13, respectively. However, the reusability of CM-
SO3H catalyst would be suggested for application of biodiesel production from WCO.
First step
Second step
0
20
40
60
80
100
5 10 15
77.5
89.680.8
%Y
ield
of
bio
die
sel
Catalyst loading (wt.%)
First step
Second step
50
Figure 4.10 FAME yield with spent catalyst at reaction temperature 110 C for 2 h
and 10 wt. % catalyst loading
Remark:
(*) The WCO was treated by sequential reacting with DI water, H3PO4, and
NaOH, respectively. First, 100ml of WCO was mixed with 5ml of DI water and stirred
at 80C for 15 min. Then the WCO was collected by centrifuged at 3500 rpm for 20
min. Next, 25g of WCO after water degumming was mixed with 0.025g (0.1 wt.% of
oil ) of H3PO4 (14%, QREC) and stirred at 80C for 5 min. After the short reaction time
the acid in partially neutralized with 0.075g (0.3 wt.% of oil ) NaOH (20% water
solution) and stirred at 80C for 5 min. The treatment WCO was collected by
centrifuged at 3500 rpm for 20 min. [77]
The structures of carbon catalyst after 3 cycles of reused was identified by
the characteristic N2 isotherms, as shown in Figure 4.11 (a). This catalyst presented
hysteresis type 1 (H1) with small adsorption volume because the pore was blocked by
reaction compounds to hinder the penetration of gas through inside the pore.
0
20
40
60
80
100
Fresh
catalyst
Fresh
catalyst
1st cycle 2nd cycle 3rd cycle
96.6
89.6
80.7
73.4 70.2
%Y
ield
of
bio
die
sel
Fresh catalyst 1st cycle 2rd cycle 3nd cycle3nd cycle2rd cycle 3nd cycle1st cycleFresh catalyst
First step
Second step
With treatment WCO (*) Without treatment WCO
51
The pore size distribution and textural properties such as BET surface area,
BJH pore size, and pore volume are reported in Figure 4.11 (b) and Table 4.1,
respectively. The decrease in the surface area carbon catalyst after 3 cycles of reused
increased the particle size, which could be observed by SEM. In addition, the surface
area of reused sulfonated carbon microsphere decreased dramatically owning to loss of
internal surface area (area inside the pore).
Figure 4.11 (a) N2 sorption isotherm and (b) pore size distribution of spent sulfonated
carbon catalyst after 3 cycles of reused
0
2
4
6
8
10
12
0 0.2 0.4 0.6 0.8 1
Volu
me
@ S
TP
[cc
/g]
Relative Pressure (P/P0)
(a)
0
0.01
0.02
0.03
1 10 100
dV
(logd
) (c
c/g)
Pore diameter (nm)
(b)
52
The morphology and particle size distribution of carbon catalyst after 3
cycles of reused are shown in a scanning electron micrograph Figure 4.12. The reused
CM-SO3H was increased the average particle diameter from 2.7 m to 3.2 m and 3.9
m for fresh catalyst, 1st reused CM-SO3H and 3rd reused CM-SO3H, respectively. Due
to the SEM micrographs of reused CM-SO3H discovered the agglomeration of the CM-
SO3H particles. Moreover, the surface of CM-SO3H was covered by reaction
compounds.
Figure 4.12 SEM microphotograph of spent sulfonated carbon catalyst of biodiesel
production.
The total acidity of reused CM-SO3H decreased from 1.38 to 0.59 mmol/g
after reused for 3 cycles which was resulted by the leaching of sulfonic acid and the
coverage of reaction compounds. The leaching of sulfonic acid was confirmed by the
decreasing of the NH3 desorption peak area of sulfonic at 250C as shown in Figure
4.13.
0
20
40
60
80
100
1 2 3 4 5
Fre
qu
en
cy
(%
)
Microsphere Size (m)
Reuse -1st cycle
Mean size (m) 3.22
Median (m) 2.56
Mode (m) 3.51
Std.Dev. 1.14
0
20
40
60
80
100
1 2 3 4 5
Fre
qu
en
cy
(%
)
Microsphere Size (m)
Reuse - 3rd cycle
Mean size (m) 3.86
Median (m) 3.24
Mode (m) 4.23
Std.Dev. 1.91
5m 5m
Reuse – 3rd cycleReuse – 1st cycle
53
Figure 4.13 NH3-TPD profile of spent sulfonated carbon catalyst after 3 cycles of
reused
4.3 Catalytic activity in furfural production via xylose dehydration
4.3.1 Effect of reaction temperature
To optimize the reaction conditions by studying the effects of reaction
temperature, reaction time and catalyst loading on xylose conversion and furfural yield,
furfural selectivity. Initially, the reaction temperature was varied from 120C to 170C.
The xylose conversion, furfural selectivity and furfural yield increased with increasing
reaction temperature as shown in Figure 4.14. However, the furfural yield and furfural
selectivity were decreased at high reaction temperature since D-xylose convert to
carbonize and degrade of catalyst which will affect the activity of the catalyst. [63, 78]
Therefore, the suitable reaction temperature 155C was shown the highest furfural yield
(22.8%) and furfural selectivity (23.9%).
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 100 200 300 400
Sig
nal
(mV
)
Temperature (C)
-COOH
-SO3H
54
Figure 4.14 Catalytic performance including xylose conversion, furfural yield and
furfural selectivity with different reaction temperature at reaction time 2h and 50
wt.% catalyst loading
4.3.2 Effect of reaction time
The effect of reaction time is shown in Figure 4.15. The reaction time did
not significantly affected xylose conversion because the chemical equilibrium was fast
approached [65]. On the other hand, furfural yield and furfural selectivity decreased as
longer reaction time due to side reaction including polymerization and oligomerization
of furfural to furanic resins, a solid residue and formation of soluble degradation
products. [78]
0
20
40
60
80
100
120 140 155 170
(%)
Reaction temperature (C)
Conversion (%) Selectivity (%) Yield (%)
55
Figure 4.15 Catalytic performance including xylose conversion, furfural yield and
furfural selectivity with different reaction times at reaction temperature 155C and 50
wt.% catalyst loading.
4.3.3 Effect of catalyst loading
The amount of catalyst was also studied from 10 wt.% to 50 wt.%. High
furfural yield and furfural selectivity would be obtained at the amount of catalyst less
than 50 wt.% as shown in Figure 4.16. According, the higher amount of catalyst
contained higher number of free active sites available for the reactant to give a higher
yield of furfural and selectivity of furfural. However, an excess amount of catalyst is
not essential for this reaction due to reduction of furfural yield and furfural selectivity.
Therefore, the suitable catalyst loading was 25 wt.% to produce 94.1%, 44.5% and
33.9% of xylose conversion, furfural selectivity, and furfural yield, respectively. [79]
0
20
40
60
80
100
1 2 3
(%)
Reaction time (h)
Conversion (%) Selectivity (%) Yield (%)
56
Figure 4.16 Catalytic performance including xylose conversion, furfural yield and
furfural selectivity with different catalyst loading at reaction temperature 155C for
2h.
To improved the furfural yield and furfural selectivity of CM-SO3H
catalyst, the P-C-SO3H containing porous structure was prepared to reduce the pore
diameter of the CM-SO3H catalyst from 6.6 nm to 3.8 nm. The catalytic activity of the
P–C–SO3H and CM–SO3H catalysts was benchmarked in dehydration of xylose to
produce furfural at reaction temperature 155C for 2 h as shown in Figure 4.17. The P-
C-SO3H catalyst could increase the furfural selectivity and furfural yield to 68.4% and
65.1% , respectively. The greater catalytic activity of P–C–SO3H as compared to CM–
SO3H could be explained on the basis of suitable pore size and pore volume of catalyst.
Because a pore diameter in the range of 3–6 nm could provide the selective in furfural
which was reported by Kaipromarat S. et al. [65]
The reusability of the catalyst was investigated over three reaction cycles.
The selectivity of furfural decreased from 72% to 30% after 3rd cycle. The significantly
decrease in furfural selectivity resulted due to the leaching of sulfonic acid groups from
spent catalyst.
0
20
40
60
80
100
10 25 50
(%)
Catalyst loading (wt.%)
Conversion (%) Selectivity (%) Yield (%)
57
Figure 4.17 Catalytic performance including xylose conversion, furfural yield and
furfural selectivity between CM-SO3H and P-C-SO3H catalysts at reaction
temperature 155C for 2 h and 25 wt.% catalyst loading.
0
20
40
60
80
100
CM-SO3H P-C-SO3H 1st cycle 2nd cycle 3rd cycle
(%)
Conversion (%) Selectivity (%) Yield (%)
CM-SO3H P-C-SO3H 1st cycle 2nd cycle 3rd cycleCM-SO3H P-C-SO3H 1st cycle
Fresh catalyst Used catalyst of P-C-SO3H
58
CHAPTER 5
CONCLUSIONS AND RECOMMENDATIONS
5.1 Conclusions
Carbon microsphere could be prepared by hydrothermal carbonization of
xylose and functionalized with sulfonic acid. In addition, a porous carbon solid acid
catalyst (P-C-SO3H) was also synthesized by activation of carbon microsphere with
potassium hydroxide to improve their porous properties.
The structure, morphology and pore volume of carbon microsphere, CM-
SO3H catalyst and P-C-SO3H catalyst were investigated. The catalysts presented large
surface area. The CM-SO3H catalyst contained the pore structure as microporous
structures. Meanwhile, the P-C-SO3H represented that disorder slit-shaped pore
tructures. Beside that SEM micrograph was shown the spherical shape with smooth
surface area and non-uniform of carbon catalyst owning with interaction of –SO3H
group on catalyst surface. The FT-IR spectral of CM-SO3H and P-C-SO3H were shown
the absorption band at 1032 cm-1 and 1171 cm-1 appeared according to O=S=O and -
SO3H, respectively. In the region of (3000 – 3390) cm-1, the absorption band of a –OH
group, which could be in the form of -SO2OH or –COOH, also appeared. In addition,
the –SO3H group was confirmed by S 2p peak of XPS spectra at 169 eV. The acidity
and acid strengh of carbon catalyst were investigated by NH3-TPD analysis. The total
acidity of CM-SO3H and P-C-SO3H were 1.38mmol/g and 1.28 mmol/g, respectively.
The optimized condition of biodiesel production from waste cooking oil
was reaction temperature 110C for 2 h, molar ratio of oil/methanol is 1:9.35 and 10
wt.% of catalyst loading. The catalyst performed good catalytic activity with 89.6%
yield of biodiesel without any treatment of waste cooking oil. The reusability of catalyst
was also investigated at the optimum condition. The biodiesel yield decreased by 21.0
% after 3 cycles.
In addition, the catalyst was tested the catalytic perforance in dehydration
of xylose to produce furfural. The highest furfural yield, furfural selectivity, and xylose
59
conversion were 39.3 %, 44.5 % and 94.1 %, respectively with CM-SO3H catalyst.
However, furfural yield and furfural selectivity could be improved by P-C-SO3H
catalyst. The P-C-SO3H catalyst contained smaller pore than CM-SO3H catalyst to
selective with furfural. The P-C-SO3H catalyst could be increase furfural yield, furfural
selectivity to 65.1 % and 68.4 % , respectively at the xylose conversion of 95.2 %.
In conclusion, the sulfonated carbon microsphere catalyst can be a
candidate the acid catalyst to perform the good performace in biodiesel production and
xylose dehydration, moreover the sulfonated carbon could be proposed the material for
environmentally benign, low-cost.
5.2 Recommendations
The thermal stability and acid strength of carbon catalyst should be
developed to improve the reusability of catalyst for both biodiesel production and
furfural production. In addition, the pore size and pore volume of catalyst still need to
be modified for improve the furfural yield and furfural selectivity.
60
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67
APPENDICES
68
APPENDIX A
Carbon microsphere characterization
The carbon microsphere was studied the effect of reaction temperature (170
– 190C), reaction time (12 h – 24 h) and weight ratio of xylose to water (10 wt.% - 50
wt.%). The yield (%) of carbon microsphere was calculated by Equation (A1).
Figure A1. Yield of carbon microsphere obtained from different conditions of
hydrothermal.
carbon microsphere
Weight of carbon produced (g)Yield (%) = x100
Weight of starting xylose (g) (A1)
The physicochemical properties of carbon microsphere were studied the
morphology and physical structure characteristic by Scanning Electron Microscope
(SEM). Confirmation of functional group by Fourier Transform Infrared spectroscopy
(FT-IR). Analysis the surface area and particle size by N2 sorption and study and
confirmation elemental carbon, hydrogen, nitrogen by CHN analyzer.
0
10
20
30
40
50
170°C 190°C 170°C 190°C 170°C 190°C 190°C
12h 16h 20h 24h
Yie
ld (
%)
10wt% 25wt% 50wt%
69
Figure A2. SEM micrograph of carbon microsphere at 190C – 50wt.% (xylose
concentration) with different reaction time.
70
Figure A3. FT-IR spectra of carbon microsphere at 190C – 50wt.% (xylose
concentration) with different reaction time.
Figure A4. N2 sorption of carbon microsphere at 190C – 50wt.% (xylose
concentration) with different reaction time.
0
10
20
30
40
50
60
70
0 0.2 0.4 0.6 0.8 1
Volu
me
@ S
TP
[cc
/g]
Relative Pressure (P/P0)
12h 16h 20h 24h
71
Demethanation Dehydration Decarboxylation
Figure A5. Van Krevelen diagram of carbon microsphere from different conditions of
hydrothermal.
Table A1. Physical properties of carbon microspheres at 190C – 50wt.% (xylose
concentration) with different reaction time.
Reaction
time (h)
BET surface area
(m2/g)
Pore size
(nm)
Pore volume
(cc/g)
12 16.1 7.8 0.032
16 31.1 4.9 0.06
20 67.0 4.5 0.07
24 95.5 3.4 0.094
72
APPENDIX B
Standard calibration curve preparation
1. Standard calibration curve for furfural production (HPLC)
First, a furfural solution was prepared by 0.01g of furfural (AR grade, 99%,
Sigma-Aldrich) was dissolved in Toluene and titrated in 10 mL volumetric flasks. Then
using that solution to prepare several standard solution in 10 mL volumetric flasks (0.2,
0.4, 0.6, 0.8 and 1.0 mM) follow by Equation (B1).
C1V1 = C2V2 (B1)
C1: Initial concentration of furfural solution ( 10.05 mM)
V1: Amount of initial furfural solution (mL)
C2: Desire concentration of furfural solution (0.2 – 1 mM)
V2: Amount of desire furfural solution (10 mL)
The linear equation of this curve is y = 9 x 106X and R2 = 0.9992 was shown
in Figure B1. This curve was used to calculated furfural yield and furfural selectivity
follow by Equation (1), (2) in Chapter 3.
Figure B1. Standard calibration curve for furfural production (HPLC)
y = 9E+06x
R² = 0.9992
0
2000000
4000000
6000000
8000000
10000000
0 0.2 0.4 0.6 0.8 1
Pea
k A
rea
Concentration (mM)
73
2. Standard calibration curve for xylose converstion (HS-GC-MS)
Xylose solution was prepared with xylose concentration (5 – 30 ppm). First,
the mixture of 1.0 mL xylose solution and 5.0 mL H2SO4 (98%, QRecC) were
transferred to the bottle. After that, the bottle was put in the water batch at 70C for 15
min. Finally, 100 L of this product was pipetted into headspace vials that contained
Na2CO3 anhydrous for analysis with HS-GC-MS. [65, 68]
The linear equation of this curve is y = 107 X and R2 = 0.9945 was shown in
Figure B2. This calibration curve was used to calculate an amount of furfural in the
sample. It also refer to the amount of xylose conversion follow Equation (3) in Chapter
3.
Figure B2. Standard calibration curve for xylose conversion (HS-GC-MS)
y = 1E+07x
R² = 0.9945
0
100000000
200000000
300000000
400000000
500000000
0 5 10 15 20 25 30
Pea
k A
rea
Concentration of xylose (ppm)
74
3. Acidity calculation
The acidity was prepared by titration method. The mixture of 0.1 g carbon
catalyst, 0.1 g NaCl and 10.0 mL DI water were stirred at room temprature for 16 h.
Then filtered and titrated with NaOH solution 0.1N. Finally, the acidity was calculated
using Equation B2.
C1V1 = C2V2 (B2)
C1: Concentration of NaOH solution (0.1M)
V1: Amount of NaOH solution was used for titration (mL)
C2: Concentration of acid catalyst (M)
V2: Amount of catalyst solution (10 mL)
After calculated concentration of carbon catalyst (M), we should change
the unit to mmol/g.
75
APPENDIX C
By-products of xylose dehydration
The by-products of xylose dehydration was determined by using toluene
phase and analysis with GC-MS.
Table C1. Yield of by-products under xylose dehydration with CM-SO3H catalyst at
different reaction temperature for 2 h and 50 wt.% catalyst loading
By-products Reaction temperature (C)
120 140 155 170
Air 0.05 0.04 0.05 0.05
Acetone (CH3)2CO 0.31 0.45 0.34 0.43
Benzene (C6H6) 0.18 0.17 0.12 0.17
Heptane (C7H14) 0.07 0.07 0.08 0.10
Norbornane (C7H12) 0.02 0.02 0.01 0.02
1,3,5-cycloheptatriene (C7H8) 80.55 86.94 74.32 73.65
1,2-dimethylcyclohexane (C8H6) 2.95 0 0 0
1,3-dimethylcyclohexane (C8H16) 2.61 0.19 0.19 0.22
Isopropylcyclopentane (C8H16) 2.45 0.19 0.21 0.21
1-Methylcycloheptene (C8H14) 1.81 0.15 0.16 0.11
Pentyl cyclopentane (C10H20) 1.79 0.68 0 0
Ethylcyclohexane (C8H16) 2.50 0.48 0.60 0.62
Benzyloxy-phenol
(C6H5CH2OC6H4OH) 0.03 0 0 0
Butylcyclopentane (C9H18) 0 0 1.05 0
76
Table C2. Yield of by-products under xylose dehydration with CM-SO3H catalyst at
different reaction time, 155C and 50 wt.% catalyst loading
By-products Reaction time (h)
1 2 3
Air 0.04 0.05 0.04
Acetone (CH3)2CO 0.28 0.34 0.21
Benzene (C6H6) 0.15 0.12 0.14
Heptane (C7H14) 0.10 0.08 0.10
Norbornane (C7H12) 0.01 0.01 0.01
1,3,5-cycloheptatriene (C7H8) 77.98 74.32 73.8
1,2-dimethylcyclohexane (C8H6) 0 0 3.00
1,3-dimethylcyclohexane (C8H16) 0.22 0.19 2.56
Isopropylcyclopentane (C8H16) 0.22 0.21 2.57
1-Methylcycloheptene (C8H14) 0.14 0.16 2.02
Pentyl cyclopentane (C10H20) 0 0.68 0
Ethylcyclohexane (C8H16) 0.62 0.63 3.42
Butylcyclopentane (C9H18) 0 0 1.05
Table C3. Yield of by-products under xylose dehydration with CM-SO3H catalyst at
155C for 2h and diffent catalyst loading
By-products Catalyst loading (wt.%)
10 25 50
Air 0.05 0.05 0.05
Acetone (CH3)2CO 0.05 0.27 0.34
Benzene (C6H6) 0 0.01 0.12
77
Heptane (C7H14) 0.06 0.16 0.08
Norbornane (C7H12) 0.02 0.02 0.01
1,3,5-cycloheptatriene (C7H8) 86.54 62.96 74.32
1,3-dimethylcyclohexane (C8H16) 2.61 0.19 0.19
Isopropylcyclopentane (C8H16) 2.45 0.19 0.21
1-Methylcycloheptene (C8H14) 0 0 0.16
Undecane (CH3(CH2)9CH3) 0 0.11 0
Dodecan (CH3(CH2)10CH3) 0.10 0 0
Ethylbenzene 0.03 0.02 0.63
Benzophenone (C13H10O) 0.64 0.66 0
Table C4. Yield of by-products under xylose dehydration with P-C-SO3H catalyst at
155C for 2h and 25 wt.% catalyst loading
By-products Reusability of P-C-SO3H catalyst
Fresh 1st cycle 2nd cycle 3rd cycle
Air 0.05 0.05 0.05 0.04
Acetone (CH3)2CO 0.01 0 0.04 0.04
Benzene (C6H6) 0.01 0.01 0.01 0.01
Heptane (C7H14) 0.09 0 0.48 0.53
1,3,5-cycloheptatriene (C7H8) 26.77 42.01 65.97 69.76
1,2,4-Trimethylcyclopentane
(C8H16) 0.02 0.06 0.06 0.06
Dodecane (CH3(CH2)10CH3) 0.10 0 0.10 0.10
Ethylbenzene 0.03 0.64 0.64 0.03
Benzophenone (C13H10O) 0.66 0.01 0 0.64
78
Table C5. Chemical structure of by-products
By-products Molecular structure
Formic acid
Acetone (CH3)2CO
Benzene (C6H6)
Heptane (C7H14)
Norbornane (C7H12)
1,3,5-cycloheptatriene (C7H8)
1,2-dimethylcyclohexane (C8H16)
1,3-dimethylcyclohexane (C8H16)
1,2,4-Trimethylcyclopentane (C8H16)
Isopropylcyclopentane (C8H16)
1-Methylcycloheptene (C8H14)
Pentylcyclopentane (C10H20)
79
Ethylcyclohexane (C8H16)
Benzyloxy-phenol (C6H5CH2OC6H4OH)
Butylcyclopentane (C9H18)
Undecane (CH3(CH2)9CH3)
Dodecan (CH3(CH2)10CH3)
Ethylbenzene (C8H10)
Benzophenone (C13H10O)
80
BIOGRAPHY
Name Miss Thi Tuong Vi Tran
Date of Birth March 3rd, 1992
Citizenship: Vietnamese
Educational Attainment 2010 - 2014: Bachelor’s degree of Petrochemistry
Technology in Industrial University of HCM
City.
2014 - 2016: Master’s degree of Science and
Technology in Thammasat University.
Scholarship 2010: Industrial University of HCMC
2014-2016: AEC Scholarship from Thammasat
University.
Publications/ certifications
Tran, T. T. V.; Kaiprommarat, S.; Kongparakul, S.; Reubroycharoen, P.;
Guan, G.; Nguyen, M. H.; Samart, C., Green biodiesel production from waste cooking
oil using an environmentally benign acid catalyst. Waste Management (2016), 52, 367-
374.
ACS/CST BOOST Skills Workshop for Young Thai Scientists and
Engineers.
Quality Assurance and Accreditation ISC/IEC 17025 and ISO/IEC 17020
Awards
Best Student Paper Award for Oral Presentation in the 3rd Asian Conference
on Biomass Science (ACBS) on January 19th, 2016, Niigata, Japan.
Conferences proceedings
81
Poster presentation in topic: “Green Production of Carbon Microsphere by
Hydrothermal Carbonization of Xylose” in Paccon Conference 2015, January, 2015
Bangkok, Thailand.
Oral presentation in topic: “Green Production of Carbon Microsphere by
Hydrothermal Carbonization of Xylose” in Biotechnology International Congress (BIC
2015), September, 2015, BITEC, Bangkok, Thailand.
Oral presentation in topic: “Sulfonated Carbon Microsphere Catalyst for
Biodiesel Production from Waste Cooking Oil” in The AUN/SEED-NET Regional
Conference on Materials Engineering (RCME 2015), October, 2015 Bangkok,
Thailand.
Oral presentation in topic: “Cleaner Biodiesel Production from Waste
Cooking Oil using a Carbon Solid Acid Catalyst” in the 5th International Conference on
Green and Sustainable Innovation (ICGSI 2015), November, 2015, Pattaya, Thailand.
Oral presentation in topic: “Development Sulfonated Carbon Microsphere
for the Catalyst of Biodiesel Production” in The 3rd Asian Conference on Biomass
Science (ACBS 2016), January, 2016, Niigata, Japan.
Work experiences
Computer: AutoCAD, ChemOffice, CorelDraw (2D), ImageJ, Microsoft
Office, Peakfit, Visio.