feo production of phenols from lignin via depolymerization and catalytic cracking

7182019 FeO Production of Phenols From Lignin via Depolymerization and Catalytic Cracking

httpslidepdfcomreaderfullfeo-production-of-phenols-from-lignin-via-depolymerization-and-catalytic-cracking 17

Production of phenols from lignin via depolymerization and catalytic cracking

Takuya Yoshikawa a Taichi Yagi a Satoshi Shinohara a Tetsuya Fukunaga b Yuta Nakasaka aTeruoki Tago a Takao Masuda a

a Research Group of Chemical Engineering Division of Chemical Process Engineering Faculty of Engineering Hokkaido University N13W8 Kita-ku Sapporo Hokkaido 060 ‐8628 Japanb Idemitsu Kosan Co Ltd Advanced Technology Research Laboratories 1280 Kami-izumi Sodegaura Chiba 299‐0293 Japan

a b s t r a c ta r t i c l e i n f o

Article history

Received 14 November 2011Received in revised form 24 April 2012

Accepted 1 May 2012

Available online xxxx

Keywords

Biomass utilization

Lignin conversion

Phenols

Iron oxide catalyst

Demethoxylation

Production of phenols from lignin was investigated using a new conversion process consisting of two reaction

steps In the 1047297rst step depolymerization of lignin was carried out in an autoclave reactor using a silica-alumina catalyst in a water1-butanol solution The yield of lignin-derived liquid product reached 85ndash88 C-

mol under the appropriate reaction conditions In the second step catalytic cracking of the liquid products

from the 1047297rst step was carried out using a 1047297xed‐bed 1047298ow reactor over an iron oxide catalyst With this meth-

od total recovered fraction of phenols and the conversion of methoxy phenol reached 66 ndash86 and 92ndash94

respectively

copy 2012 Elsevier BV All rights reserved

1 Introduction

From the perspective of fossil fuel depletion and the need for controlof carbon dioxide emissions the production of fuels and useful chemicals

from lignocellulose which is the most abundant inedible biomass in na-

ture is becoming increasingly important [1ndash3] Lignocellulose resources

arecomposed of cellulose hemicellulose andlignin Recently the produc-

tion of bio-ethanol from cellulose and hemicellulose has been developed

worldwide [4] In these production processes lignin is removed as resi-

due Lignin is a high molecular weight polymer composed of alkylphenol

unitsThereforeit canbe regarded as a rich source of phenols However it

is dif 1047297cult to decompose lignin into phenols because of its complex

structure

Various methods for the production of phenols from lignocellu-

lose especially lignin have been reported such as solvolysis including

hydrolysis hydrocracking (hydrogenolysis) pyrolysis and alkaline

oxidation [56] Early studies on lignin hydrolysis using homogeneous

acid catalysts aimed at structural analysis of lignin resulting in the

formation of carbonaceous residue whereas it was reported that the

use of base catalysts such as NaOH and KOH [78] and RbCO3 and

CsCO3 [9] was effective in the decrease in char formation and the pro-

duction of phenolic compounds Famous study on hydrocracking of

lignin was the patented Noguchi process in which iron (II) sul1047297de

based catalyst was used at 523ndash723 K under 15ndash46 MPa of initial hy-

drogen pressure [10] In addition to conventional CondashMo and NindashMo

based catalysts in petrochemical industry various kinds of heteroge-

neous catalysts including VAl2O3 [11] and MgOndashAl2O3 [12] were ap-

plied to hydrocracking of lignin or its model compounds Not onlymolecular hydrogen but also hydrogen donating solvent such as

tetralin [13] and formic acid [14] was also used as hydrogen source

of hydrocracking Most of early research on pyrolysis lignin or bio-

mass focused on the production of bio-oil (or bio-fuel) whereas re-

cent studies related to the production of phenols by pyrolysis of

biomass and its model compounds were reviewed [15] Upgrading

of bio-oil to produce aromatic compounds was also investigated

using zeolite or other solid acid catalysts [1617] Alkaline oxidation

of lignin produces aromatic aldehydes Nitrobenzene metal oxides

and oxygen are preferable oxidants to preserve aromatic rings in lig-

nin [18] Because a part of arti1047297cial vanillin is commercially produced

by alkaline oxidation of lignin sulfonate which is a by-product of sul-

1047297te pulping process the possible application of kraft lignin which is

produced in plenty from main stream of pulp industry has been in-

vestigated recently [1920]

We focus on the possibility of production of lignin-derived phe-

nols and propose a new conversion process that consists of two reac-

tion steps as shown in Scheme 1 First lignin is depolymerized into

lower molecular weight liquid products and partly into lignin con-

stituent monomers dimers and oligomers In this study the obtained

liquid products are referred to as the lignin-derived slurry liquid For

this step of the process hydrolysis of lignin was carried out using a

solid acid catalyst in a wateralcohol mixed solution Next the

lignin-derived slurry liquid is converted into phenols For this catalyt-

ic conversion of biomass resources we have developed an iron oxide

catalyst and have succeeded in carrying out the selective production

Fuel Processing Technology xxx (2012) xxxndashxxx

Corresponding author Tel +81 11 706 6551 fax +81 11 706 6552

E-mail address tagoenghokudaiacjp (T Tago)

FUPROC-03440 No of Pages 7

0378-3820$ ndash see front matter copy 2012 Elsevier BV All rights reserved

doi101016jfuproc201205003

Contents lists available at SciVerse ScienceDirect

Fuel Processing Technology

j o u r n a l h o m e p a g e w w w e l s e v i e r c o m l o c a t e f u p r o c

Please cite this article as T Yoshikawa et al Production of phenols from lignin via depolymerization and catalytic cracking Fuel ProcessTechnol (2012) doi101016jfuproc201205003



of phenols and ketones from tar derived from wood biomass [21ndash23]

In addition this catalyst is active for the decomposition of lignin con-

stituent monomers and dimers [24] For these reasons catalytic

cracking of the lignin-derived slurry liquid was carried out using

this catalyst

In this study the optimal reaction conditions for the depolymeri-

zation of lignin were investigated and the reaction mechanism is dis-

cussed In addition the possible application of the iron oxide catalyst

in the second step of the process was examined

2 Experimental

21 Depolymerization of lignin

Depolymerization of lignin was carried out in an autoclave reactor

made of Hastelloy alloy C-276 (KH-50 Hiro Co Ltd) with an inner vol-

ume of 36 cm3 at 473ndash623 K for 05ndash8 h Organosolv lignin propionate

(Alrdich abbreviated as OSL ‐Pr) or kraft lignin (Tokyo Chemical Indus-

try abbreviated as KL) silica-alumina with an SiAl= 2 (N631HN Nikki

Chemical Co Ltd) and a mixed solution of distilled water (H2O)and 1-

butanol (BuOH) were placed into the reactor The weight ratio of lignin

to silica-alumina to solvent was 1047297xed at 1130 The molar ratio of H2O

to BuOH varied in the range of 1ndash10 and only H2O or BuOH was also

used Other organic solvents such as ethanol (EtOH) and benzene

were used for comparison The reactor was swung back and forth

about 20 times per minute during the reaction

Scheme2 shows the analytical procedure for the depolymerizationreaction of lignin After termination of the reaction the gaseous

products were collected with a gas pack and the remains in the reac-

tor were 1047297ltered to obtain the lignin-derived slurry liquid and any

solid products The gaseous products were analyzed using gas

chromatographs with thermal conductivity and 1047298ame ionization de-

tectors (GC-8A Shimadzu Co Ltd) with activated charcoal and

Porapak Q columns respectively The lignin-derived slurry liquid

was analyzed using a gas chromatograph with a 1047298ame ionization de-

tector (GC-2014 Shimadzu Co Ltd) and a gas chromatographndashmass

spectrometer (GC-17A GCMS-QP5050 Shimadzu Co Ltd) with a DB-

Wax capillary column Thermal analysis of the slurry liquid was car-

ried out under a nitrogen atmosphere with a thermal gravimetric an-

alyzer (TGA-50 Shimadzu Co Ltd) The temperature program wasset as follows after holding at 323 K for 1 h to remove solvent in

the slurry liquid heating was carried out from 323 K to 823 K at a

rate of 5 Kmin The carbon content of the solid product which con-

sists of a mixture of the coke deposited on the catalyst and the resi-

due was analyzed using an elemental analyzer (ECS 4010 Costech

Instruments)

Carbon yield of the products was calculated based on carbon con-

tent of lignin put into the autoclave reactor Carbon content of OSL ‐Pr

and KL was analyzed using an elemental analyzer and was found to

be 545 wt and 511 wt respectively

22 Preparation and characterization of the iron oxide catalyst

The iron oxide catalyst was prepared via co-precipitation meth-

od 19 g of ZrO(NO3)2∙2H2O 72 g of Al(NO3)3∙9H2O and 40 g of

Fe(NO3)3∙9H2O was dissolved in 750 cm3 of distilled water 10 wt

of ammonia solution was added to the solution with micro pump

adjusting the pH to 7 All reagents were purchased from Wako Pure

Chemical Industries(Japan) and were used without further puri1047297cation

The precipitate was 1047297ltered and oven-dried at 383 K overnight to get

the catalyst precursor which was subsequently calcined at 773 K for

2 h in an air atmosphere The obtained catalyst are denoted as ZrO 2ndash

Al2O3ndashFeOX hereafter The ZrO2 and Al2O3 content in the catalyst was

analyzed by X-ray 1047298uorescence analysis (XRF Supermini Rigaku Co

Ltd) and was found to be 9 wt ZrO2 and 6 wt Al2O3

23 Catalytic cracking of the lignin-derived slurry liquid over

ZrO 2ndash Al 2O 3ndashFeO X

The lignin-derived slurry liquid consisted of two phases a water

and a BuOH phase Because the targeted chemicals were mainly

found in the BuOH phase (see Section 32) and the process of solvent

removal from BuOH phase possibly led to the loss of phenols in the

slurry liquid catalytic cracking of the BuOH phase containing the sol-

vent was carried out using a 1047297xed-bed 1047298ow reactor at 673 K for 2 h

under atmospheric pressure N2 gas was introduced as a carrier gas

at a 1047298ow rate of 10 cm3min The time factor W F was 0 (without cat-

alyst) or 1 h where W is the amount of catalyst and F is the 1047298ow rate

of feedstock F H2OF was 1 where F H2O was the 1047298ow rate of steam The

liquid and gaseous products were collected with an ice trap and a gas

pack respectively The liquid products were analyzed using a gas

chromatograph with a 1047298ame ionization detector (GC-2014 Shimadzu

Co Ltd) anda gas chromatographndashmass spectrometer (GC-17A GCMS-QP5050 Shimadzu Co Ltd) with a DB-Wax capillary column The gas-

eous products were analyzed using gas chromatographs with thermal

conductivity and 1047298ame ionization detectors (GC-8A Shimadzu Co

Ltd) with activated charcoal and Porapak Q columns respectively

3 Results and discussion

31 Effect of solvent composition on the yield of lignin-derived slurry liquid

Depolymerization of OSL ‐Pr was carried out in different composi-

tions of H2OBuOH solutions at 473 K for 3 h Fig 1 shows the effect of

the molar ratio of H2O to BuOH in the solvent on the yield of lignin-

derived slurry liquid The yields of slurry liquid were higher when

H2OBuOH solutions were used than those obtained in water or

Scheme 1 Outline of the process for the production of phenols from lignin

Scheme 2 Analytical procedure of depolymerization reaction of lignin

2 T Yoshikawa et al Fuel Processing Technology xxx (2012) xxxndash xxx




BuOH alone and the yield of liquid product reached 96 C-mol at

H2OBuOH=4 Fig 2 shows the yields of identi1047297ed products in the

slurry liquids depicted in Fig 1 as determined by gas chromatogra-

phy The phenols mainly consisted of methoxyphenol and its yield

was about 06ndash08 C-mol when the mixture of H2OBuOH was

used The carboxylic acids consisted mainly of propionic acid It was

reported that lignin esters were produced in the reaction of rawlignin

with acid anhydride resulting in the esteri1047297cation of OH groups in

raw lignin [2526] Because esteri1047297cation reaction is generally reverse

reaction propionic acid was considered to be formed by hydrolysis of

the substituent groups of OSL ‐Pr The carboxylate esters consisted

mainly of butyl propionate It was reported that esteri1047297cation of car-

boxylic acid and alcohol proceeded over various kinds of solid acid

catalysts [27] Therefore carboxylate esters were assumed to be

mainly produced by the reaction of the carboxylic acids and BuOH

over the silica-alumina

32 Investigation of the reaction route for depolymerization of lignin

To clarify the function of H2OBuOH solution during the depoly-

merization of lignin the distribution of each component identi1047297edby gas chromatography in each phase was investigated and the re-

sults are summarized in Table 1 The distribution was calculated as

the proportion of the carbon amount in the water (or BuOH) phase

to the total carbon amount in both the water and BuOH phases The

phenols and carboxylate esters mainly existed in the BuOH phase It

is believed that hydrolysis of lignin over silica-alumina mainly oc-

curred in the water phase to produce phenolic compounds and thus

the extraction of the phenolic compounds from the H2O phase into

the BuOH phase promoted the reaction leading to the improvement

of the yield of the lignin-derived slurry liquid When the carboxylic

acids were esteri1047297ed with BuOH over silica-alumina the ester com-

pounds were then extracted to the BuOH phase as well Some of the

carboxylic acids would however be recombined with other products

resulting in the formation of the carbonaceous residue Accordingly

an additional function of the H2OBuOH solution was assumed to be

suppression of the recombination reactions of the carboxylic acids

with the degraded lignin compounds Based on the above discussion

the expected reaction routes are shown in Fig 3 one is the extraction

of the degraded aromatic compounds from the water phase to the

BuOH phase and the other is esteri1047297cation of the carboxylic acids

with BuOH followed by extraction of the produced carboxylate esters

from the water phase to the BuOH phase Considering depolymeriza-

tion of lignin using H2OBuOH solution was caused by hydrolysis in

water phase the expected reaction formula was shown in Fig 4 re-

ferring to the reaction mechanism of lignin depolymerization using

acid catalysts [28] The reaction mechanism of Because lignin has a

complex structure and lignin-derived slurry liquid contained the uni-

denti1047297ed and undetectable products by gas chromatography the

structure of OSL ‐Pr in Fig 4 was simpli1047297ed using the basic unit de-

scribed in the Section 34

Depolymerization of lignin using other organic solvents was carriedout for comparison with the reaction using the H2OBuOH solution

Fig 5 shows the results of depolymerization of lignin using H2OEtOH

and H2Obenzene as a solvent at 573 K for 2 h The yields of lignin-

derived slurry liquid using the H2OEtOH and H2Obenzene solutions

were lower than that obtained with H2OBuOH While EtOH does un-

dergo the esteri1047297cation reaction with carboxylic acids it is completely

miscible in water and thus the extraction of degraded aromatic com-

pounds did not occur in the H2OEtOH solution On the other hand in

the H2Obenzene solution the degraded aromatic compounds were

extracted from the water phase into the benzene phase while esteri1047297-

cation of benzene with the carboxylic acids did not proceed These

properties were assumed to cause the low yields of lignin-derived slur-

ry liquid using H2OEtOH and H2Obenzene Therefore the ability to

0 20 40 60 80 100

0 (BuOH)

1

4

10

(H2O)

H2OBuOH

(molar ratio)

Liquid product Solid product

Carbon yield based on lignin C-mol

Identified by GC(BuOH phase)

Identified by GC(Water phase)

Unidentified

+ undetectable by GC

Coke + Residue

Fig 1 Effect of the molar ratio of H2O to BuOH solutions on the yield of lignin-derived slurry liquid Reaction conditions OSL ‐Pr reaction temperature and time=473 K 3 h

0 5 10 15 20 25 30 35


Carboxylic esters

Carboxylate acids

Alcohol

Phenols0 (BuOH)

1

4

10

(H2O)

H2OBuOH

(molar ratio)

Fig 2 Yields of identi1047297ed products by GC in the slurry liquids in Fig 2 Reaction condi-

tions OSL ‐Pr reaction temperature and time=473 K 3 h

Table 1

The distribution of each component identi1047297ed by GC in the water and BuOH phases in

Fig 2

Component Phenols Carboxylate ester

H2OBuOH (molar ratio) 1 4 10 1 4 10

BuOH phaseC-mol 99 93 73 100 99 96

Water phaseC-mol 10 70 27 00 10 40

Component Carboxylic acid Alcohol


BuOH phaseC-mol 99 74 31 95 46 21


3T Yoshikawa et al Fuel Processing Technology xxx (2012) xxxndash xxx




both undergo esteri1047297cation reactions with the carboxylic acids and to

extract the phenolic compounds is required for an organic solvent

and it is concluded that mixed solutions of water and a relatively hydro-

phobic alcohol such as BuOHare suitable as solvents for the depolymer-

ization of lignin

33 Effect of reaction conditions

Table 2 (a) and (b) shows the effects of reaction temperature and

time respectively on the yield of lignin-derived slurry liquid and

phenols using H2OBuOH at the molar ratio of 4 As shown in

Table 2 (a) the yield of phenols increased as the temperature in-

creased from 473 K to 573 K whereas the yield of phenols and

lignin-derived slurry liquid decreased at 623 K Because the BuOH

phase of the slurry liquid was dark brown in contrast to the waterphase which was a nearly colorless and transparent solution it was

determined that the lignin-derived products were mainly contained

in the BuOH phase For this reason TGA analyses were conducted

using the BuOH phase Fig 6 (a) shows the results of the TGA analyses

of the BuOH phases of the slurry liquids obtained under the condi-

tions shown in Table 2 (a) The weight loss curves of the lignin-

derived products in the BuOH phase shifted to the lower temperature

region as the depolymerization temperature increased from 473 K to

623 K Weight loss of a sample in the lower temperature region of a

TGA analysis indicates that the sample consists of chemicals with

lower molecular weights Accordingly this shift indicated that the

lignin-derived products became lighter and depolymerization of lig-

nin proceeded further with increasing reaction temperature With re-

spect to the effect of reaction time (Table 2 (b)) the yield of phenols

increased as the reaction time increased from 05 h to 2 h whereas

the yield of lignin-derived slurry liquid slightly decreased at 8 h

TGA analyses of the BuOH phases of the slurry liquids obtainedunder the conditions shown in Table 2 (b) were also conducted

There were no signi1047297cant differences of the weight loss curves of

lignin-derived products in the BuOH phases between 05 and 8 h of

reaction time From these results it was concluded that recombina-

tion reactions as well as depolymerization of lignin proceeded

under excessive conditions resulting in a decrease in the yield of phe-

nols andor lignin-derived slurry liquid and that the appropriate re-

action temperature and time were 573ndash623 K and 2ndash4 h for this

study

The depolymerization reaction was then applied to KL another

type of lignin that is a by-product obtained from a mainstream pro-

cess of the chemical pulp industry Fig 7 shows the results of depoly-

merization of KL at 573 K for 2 h The yield of KL-derived slurry liquid

reached a maximum at H2OBuOH=4 In addition the KL ‐derived

products in the BuOH phase obtained at H2OBuOH=4 were ana-

lyzed by TGA and the change in weight loss of the products with tem-

perature was compared with raw KL as shown in Fig 6 (b) The curve

of the product shifted to the lower temperature region as compared

with KL indicating that KL was also effectively depolymerized by

this method Therefore the 1047297rst step of the process was applicable

to KL as well as OSL ‐Pr

34 Catalytic cracking of lignin-derived slurry liquid over ZrO 2ndash Al 2O 3ndashFeO X

For the above-mentioned reasons (see Section 23 and Table 1)

catalytic cracking of BuOH phase containing the solvent was carried

out over ZrO2ndashAl2O3ndashFeOX It was reported that the partial oxidation

of alcohol to produce carboxylic acid occurred followed by theketonization of carboxylic acid over iron oxide catalyst [2329] In ad-

dition it was con1047297rmed that catalytic reaction of BuOH alone over

ZrO2ndashAl2O3ndashFeOX didnt produce any phenols Therefore this study

focused on phenols among whole products after the reaction Fig 8

(a) shows the typical recovered fraction of phenols after the reaction

of the OSL-Pr slurry liquid The recovered fraction was calculated

based on the assumption that the constituent monomer of OSL ‐Pr is

26-dimethoxy-4-(12-dihydroxy-3-propionyloxy)-propylphenol

BuOH Phase

BuOH

OH

OO OH

O

OH

OO

OH

O

OH

O

O

O

Water

Phase

Lignin(OSL Pr) Silica-alumina

RecombinationHydrolysis

Esterification

Fig 3 Expected reaction routes in the depolymerization of lignin (OSL ‐Pr) using H2O

BuOH solution over silica-alumina

CH

CH

OH

CH2

O

O

O

C2H

5

O

OH

O

CH3H3C

H2O+

Lignin

Further

depolymerization

Lignin OH

C2H5COOH

CH3H3C

C4H9OH+C2H5COOC4H9 H2O+

CH2

C

OH

CH2

OH

O O

O

Fig 4 Expected reaction formula of the depolymerization of lignin (OSL ‐Pr) using H2OBuOH solution over silica-alumina





and the recovered fraction was obtained using the following equa-

tions

mols of aromatic ring in lignin

frac14 weight of lignin used for the depolymerization reaction

molecular weight of constituent monomereth1THORN

mols of aromatic ring in phenols after the catalytic cracking

frac14 carbon mols of the obtained phenols

carbon numbers in one molecular of the phenolseth2THORN

From Eq (1) mols of aromatic ring in lignin put into the autoclave

reactor was calculated using the basic unit of lignin and from Eq (2)

mols of aromatic ring in phenols were calculated based on the GC

analysis of products obtained after the catalytic reaction over ZrO2ndash

Al2O3ndashFeOX From (1) and (2)

recovered fraction of phenols=

frac14 mols of aromatic ring in phenols

mols of aromatic ring in lignin 100 eth3THORN

Without any catalyst the recovered fraction slightly increased and its

composition was almost the same as that in the lignin-derived slurry liq-

uid On the other hand the recovered fraction of phenols increased after

reaction over ZrO2ndashAl2O3ndashFeOX This result indicated that lignin-derived

compounds in the slurry liquid were converted into phenols over ZrO2ndash

Al2O3ndashFeOX In addition methoxyphenol drastically decreased and

phenol and cresol increased This result is in good agreement with that

of a reaction using a lignin constituent-related aromatic as a model

compound Speci1047297cally guaiacol (2-methoxyphenol) was selectively

converted into phenol over ZrO2ndashAl2O3ndashFeOX [10] Therefore it is

considered that methoxyphenol in the slurry liquid was selectively

decomposed via a reaction path similar to that involved in the reaction

of guaiacol

Catalytic cracking of the KL-derived slurry liquid was also carried

out Fig 8 (b) shows a typical recovered fraction of phenols after

the reaction The recovered fraction was calculated with the assump-

tion that the constituent monomer of KL is 2-methoxy-4-(23-

0 20 40 60 80 100

H2O

BuOH

H2O

Benzene

H2O

EtOH

Solvent

species


Identified by GC(Organic phase)


Unidentified


Coke + Residue

Identified by GC

Fig 5 Effect of solvent on the yield of lignin-derived slurry liquid Reaction conditions OSL ‐Pr H2Oorganic solvent=4 reaction temperature and time =573 K 2 h

Table 2

Effects of (a) reaction temperature and (b) reaction time on the yield of lignin-derived

slurry liquid and phenols Reaction conditions OSL ‐Pr H2OBuOH=4 (a) reaction

time=2 h (b) reaction temperature=573 K

(a) Effect of reaction temperature

TemperatureK 473 523 573 623

(PressureMPa) (11) (41) (97) (23)

PhenolsC-mol 044 13 30 20

Lignin-derived slurry liquidC-mol 88 91 88 86

Reaction time=2 h

(b) Effect of reaction time

Timeh 05 2 4 8


Lignin-derived slurry liquidC-mol 88 87 81

Reaction temperature=573 K

473 673 8730

02

04

06

08

10

Temperature K

273

(a) OSL Pr

rawOSL Pr

523 K

473 K

623 K

573 K

W e i g h t C h a n g e ( W W 0 )


0

02

04

06

08

10

473 673 873273

Temperature K

raw KL

KL derived

slurry liquid(BuOH phase)

(b) KL

Fig 6 Results of TGA analysis of lignin-derived slurry liquid (BuOH phase) W0 The

weight after holding at 323 K for 1 h under N 2 atmosphere Reaction conditions (a)

OSL ‐Pr H2OBuOH= 4 reaction temperature and time= 473ndash623 K 2 h (b) KL H2O

BuOH=4 reaction temperature and time=573 K 2 h





dihydroxy-1-mercapt)-propylphenol Demethoxylation of the phe-

nols proceeded similarly and the total recovered fraction of phenols

increased over ZrO2ndashAl2O3ndashFeOX From these results it can be con-

cluded that this catalyst is effective for the decomposition of lignin-

derived slurry liquids

4 Conclusions

To produce phenols from lignin a two-step process consisting of

depolymerization and catalytic cracking was carried out In the 1047297rst

step depolymerization of OSL ‐Pr over silica-alumina was promoted

using a H2OBuOH solution The function of H2OBuOH was assumed

to be the extraction of the degraded compounds such as phenolic

compounds and carboxylic acids from the water phase into BuOH

phase The most appropriate reaction conditions including solvent

composition depolymerization temperature and time were found

to be H2OBuOH=4 573ndash623 K and 2ndash4 h respectively This reaction

was also applicable to KL For the second step the BuOH phase of the

lignin-derived slurry liquid obtained in the 1047297rst step was used as the

feedstock After the reaction over ZrO2ndashAl2O3ndashFeOX the total recov-

ered fraction of phenols increased and the substituted phenols

were simpli1047297ed into phenol and cresol These results therefore indi-cate that this process provides a method for producing phenols

from lignin

Acknowledgments

This work was supported by the Global COE Program (Project No

B01 Catalysis as the Basis for Innovation in Materials Science) from

the Ministry of Education Culture Sports Science and Technology

Japan

0 20 40 60 80 100




Unidentified+ undetectable by GC

Coke + Residue

0 (BuOH)

4

(H2O)

H2OBuOH

(molar ratio)

Fig 7 Product yields after the depolymerization of KL Reaction conditions KL reaction temperature and time=573 K 2 h

After depolymerization

of OSL Pr

(BuOH phase)

Without catalyst

ZrO2 Al2O3 FeOX

ZrO2 Al2O3 FeOX

Recovery fraction of phenols

(a) Catalytic cracking of OSL Pr derived slurry liquid

0 2 4 6 8 10

Alkyl phenol

Methoxy phenol

Phenol + Cresol

0 2 4 6 8 10



of KL

(BuOH phase)

(b) Catalytic cracking of KL derived slurry liquid

Without catalystAlkyl phenol

Methoxy phenol

Phenol + Cresol

Fig 8 Recovery fraction of phenols after the reaction of (a) OSL ‐Pr derived slurry liquid (b) KL

‐derived slurry liquid Reaction conditions reaction temperature and time =673 K 2 h





References

[1] E-J Ras B McKay G Rothenberg Understanding catalytic biomass conversionthrough data mining Topics in Catalysis 53 (2010) 1202ndash1208

[2] A Demirbaş Biomass resource facilities and biomass conversion processing forfuels and chemicals Energy Conversion and Management 42 (2001) 1357ndash1378

[3] A Corma S Iborra A Velty Chemical routes for the transformation of biomassinto chemicals Chemical Reviews 107 (2007) 2411ndash2502

[4] M Galbe G Zacchi A review of the production of ethanol from softwood AppliedMicrobiology and Biotechnology 59 (2002) 618ndash628

[5] MP Pandey CS Kim Lignin depolymerization and conversion a review of ther-

mochemical methods Chemical Engineering and Technology 34 (2011) 29ndash41[6] J Zakzeski PCA Bruijnincx AL Jongerius BM Weckhuysen The catalytic valo-

rization of lignin for the production of renewable chemicals Chemical Reviews110 (2010) 3552ndash3599

[7] JS Shabtai WW Zmierczak E Chornet US Patent 5 959 167 (1999)[8] JE Miller L Evans A Littlewolf DE Trudell Batch microreactor studies of lignin

and lignin model compound depolymerization by bases in alcohol solvents Fuel78 (1999) 1363ndash1366

[9] S Karagoumlz T Bhaskar A Muto Y Sakata Effect of Rb and Cs carbonates for pro-duction of phenols from liquefaction of wood biomass Fuel 83 (2004)2293ndash2299

[10] DW Goheen Hydrocracking of lignin by the Noguchi process Advances inChemistry Series 59 (1966) 205ndash225

[11] J Filley C Roth Vanadium catalyzed guaiacol deoxygenation Journal of Molecu-lar Catalysis A Chemical 139 (1999) 245ndash252

[12] Z Strassberger S Tanase G Rothenberg Reductive dealkylation of anisole andphenetole towards practical lignin conversion European Journal of OrganicChemistry 2011 (2011) 5246ndash5249

[13] F Davoudzadeh B Smith E Avni RW Coughlin Depolymerization of lignin atlow pressure using lewis acid catalysts and under high pressure using hydrogendonor solvents Holzforschung 39 (1985) 159ndash166

[14] M Kleinert T Barth Phenols from lignin Chemical Engineering and Technology31 (2008) 736ndash745

[15] C Amen-Chen H Pakdel C Roy Production of monomeric phenols by thermo-chemical conversion a review Bioresource Technology 79 (2001) 277ndash299

[16] JD Adjaye NN Bakhshi Production of hydrocarbons by catalytic upgrading of afast pyrolysis bio-oil Part I Conversion over various catalysts Fuel ProcessingTechnology 45 (1995) 161ndash183

[17] RK Sharma NN Bakhshi Catalytic upgrading of pyrolysis oil Energy amp Fuels 7(1993) 306ndash314

[18] G Wu M Heitz E Chornet Improved alkaline oxidation process for the produc-tion of aldehydes (vanillin and syringaldehyde) from steam-explosion hardwoodlignin Industrial and Engineering Chemistry Research 33 (1994) 718ndash723

[19] JC Villar A Caperos F Garciacutea-Ochoa Oxidation of hardwood kraft-lignin to phe-nolic derivatives with oxygen as oxidant Wood Science and Technology 35(2001) 245ndash255

[20] AL Mathias AB Rodrigues Production of vanillin by oxidation of pine kraft lig-nins with oxygen Holzforschung 49 (1995) 273ndash278

[21] T Masuda Y Kondo M Miwa T Shimotori SR Mukai K Hashimoto M Takano

S Kawasaki S Yoshida Recovery of useful hydrocarbons from oil palm wasteusing ZrO2 supporting FeOOH catalyst Chemical Engineering Science 56 (2001)897ndash904

[22] D Na-Ranong R Yuangsawad T Tago T Masuda Recovery of useful chemicalsfrom oil palm shell-derived oil using zirconia supporting iron oxide catalysts Ko-rean Journal of Chemical Engineering 25 (2008) 426ndash430

[23] D Mansur T Yoshikawa K Norinaga J Hayashi T Tago T Masuda Production of ketones from pyroligneous acid of woody biomass pyrolysis over an iron-oxidecatalyst Fuel (in press)

[24] T Yoshikawa D Na-Ranong T Tago T Masuda Oxidative cracking of aromaticcompounds related to lignin constituents with steam using ZrO2ndashAl2O3ndashFeOX cat-alyst Journal of the Japan Petroleum Institute 53 (2010) 178ndash183

[25] SC Fox AG McDonald Chemical and thermal characterization of three industri-al lignins and their corresponding lignin esters BioResources 5 (2010) 990ndash1009

[26] Y Teramoto SH Lee T Endo Y Nishio Scale of homogeneous mixing in miscibleblends of organosolv lignin esters with poly(ε-caprolactone) Journal of WoodChemistry and Technology 30 (2010) 330ndash347

[27] TA Peters NE Benes A Holmen JTF Keurentjes Comparison of commercialsolid acid catalysts for the esteri1047297cation of acetic acid with butanol Applied Catal-

ysis A General 297 (2006) 182ndash188[28] T Yokoyama Y Matsumoto Revisiting the mechanism of b-O-4 bond cleavage

during acidolysis of lignin Part 1 kinetics of the formation of enol ether fromnon-phenolic C6-C2 type model compounds Holzforschung 62 (2008) 164ndash168

[29] S Funai Y Satoh Y Satoh K Tajima T Tago T Masuda Development of a newconversion process consisting of hydrothermal treatment and catalytic reactionusing ZrO2ndashFeOX catalyst to convert fermentation residue into useful chemicalsTopics in Catalysis 53 (2010) 654ndash658





of phenols and ketones from tar derived from wood biomass [21ndash23]

In addition this catalyst is active for the decomposition of lignin con-

stituent monomers and dimers [24] For these reasons catalytic

cracking of the lignin-derived slurry liquid was carried out using

this catalyst

In this study the optimal reaction conditions for the depolymeri-

zation of lignin were investigated and the reaction mechanism is dis-

cussed In addition the possible application of the iron oxide catalyst

in the second step of the process was examined

2 Experimental

21 Depolymerization of lignin

Depolymerization of lignin was carried out in an autoclave reactor

made of Hastelloy alloy C-276 (KH-50 Hiro Co Ltd) with an inner vol-

ume of 36 cm3 at 473ndash623 K for 05ndash8 h Organosolv lignin propionate

(Alrdich abbreviated as OSL ‐Pr) or kraft lignin (Tokyo Chemical Indus-

try abbreviated as KL) silica-alumina with an SiAl= 2 (N631HN Nikki

Chemical Co Ltd) and a mixed solution of distilled water (H2O)and 1-

butanol (BuOH) were placed into the reactor The weight ratio of lignin

to silica-alumina to solvent was 1047297xed at 1130 The molar ratio of H2O

to BuOH varied in the range of 1ndash10 and only H2O or BuOH was also

used Other organic solvents such as ethanol (EtOH) and benzene

were used for comparison The reactor was swung back and forth

about 20 times per minute during the reaction

Scheme2 shows the analytical procedure for the depolymerizationreaction of lignin After termination of the reaction the gaseous

products were collected with a gas pack and the remains in the reac-

tor were 1047297ltered to obtain the lignin-derived slurry liquid and any

solid products The gaseous products were analyzed using gas

chromatographs with thermal conductivity and 1047298ame ionization de-

tectors (GC-8A Shimadzu Co Ltd) with activated charcoal and

Porapak Q columns respectively The lignin-derived slurry liquid

was analyzed using a gas chromatograph with a 1047298ame ionization de-

tector (GC-2014 Shimadzu Co Ltd) and a gas chromatographndashmass

spectrometer (GC-17A GCMS-QP5050 Shimadzu Co Ltd) with a DB-

Wax capillary column Thermal analysis of the slurry liquid was car-

ried out under a nitrogen atmosphere with a thermal gravimetric an-

alyzer (TGA-50 Shimadzu Co Ltd) The temperature program wasset as follows after holding at 323 K for 1 h to remove solvent in

the slurry liquid heating was carried out from 323 K to 823 K at a

rate of 5 Kmin The carbon content of the solid product which con-

sists of a mixture of the coke deposited on the catalyst and the resi-

due was analyzed using an elemental analyzer (ECS 4010 Costech

Instruments)

Carbon yield of the products was calculated based on carbon con-

tent of lignin put into the autoclave reactor Carbon content of OSL ‐Pr

and KL was analyzed using an elemental analyzer and was found to

be 545 wt and 511 wt respectively

22 Preparation and characterization of the iron oxide catalyst

The iron oxide catalyst was prepared via co-precipitation meth-

od 19 g of ZrO(NO3)2∙2H2O 72 g of Al(NO3)3∙9H2O and 40 g of

Fe(NO3)3∙9H2O was dissolved in 750 cm3 of distilled water 10 wt

of ammonia solution was added to the solution with micro pump

adjusting the pH to 7 All reagents were purchased from Wako Pure

Chemical Industries(Japan) and were used without further puri1047297cation

The precipitate was 1047297ltered and oven-dried at 383 K overnight to get

the catalyst precursor which was subsequently calcined at 773 K for

2 h in an air atmosphere The obtained catalyst are denoted as ZrO 2ndash

Al2O3ndashFeOX hereafter The ZrO2 and Al2O3 content in the catalyst was

analyzed by X-ray 1047298uorescence analysis (XRF Supermini Rigaku Co

Ltd) and was found to be 9 wt ZrO2 and 6 wt Al2O3

23 Catalytic cracking of the lignin-derived slurry liquid over

ZrO 2ndash Al 2O 3ndashFeO X

The lignin-derived slurry liquid consisted of two phases a water

and a BuOH phase Because the targeted chemicals were mainly

found in the BuOH phase (see Section 32) and the process of solvent

removal from BuOH phase possibly led to the loss of phenols in the

slurry liquid catalytic cracking of the BuOH phase containing the sol-

vent was carried out using a 1047297xed-bed 1047298ow reactor at 673 K for 2 h

under atmospheric pressure N2 gas was introduced as a carrier gas

at a 1047298ow rate of 10 cm3min The time factor W F was 0 (without cat-

alyst) or 1 h where W is the amount of catalyst and F is the 1047298ow rate

of feedstock F H2OF was 1 where F H2O was the 1047298ow rate of steam The

liquid and gaseous products were collected with an ice trap and a gas

pack respectively The liquid products were analyzed using a gas

chromatograph with a 1047298ame ionization detector (GC-2014 Shimadzu

Co Ltd) anda gas chromatographndashmass spectrometer (GC-17A GCMS-QP5050 Shimadzu Co Ltd) with a DB-Wax capillary column The gas-

eous products were analyzed using gas chromatographs with thermal

conductivity and 1047298ame ionization detectors (GC-8A Shimadzu Co

Ltd) with activated charcoal and Porapak Q columns respectively

3 Results and discussion

31 Effect of solvent composition on the yield of lignin-derived slurry liquid

Depolymerization of OSL ‐Pr was carried out in different composi-

tions of H2OBuOH solutions at 473 K for 3 h Fig 1 shows the effect of

the molar ratio of H2O to BuOH in the solvent on the yield of lignin-

derived slurry liquid The yields of slurry liquid were higher when

H2OBuOH solutions were used than those obtained in water or

Scheme 1 Outline of the process for the production of phenols from lignin

Scheme 2 Analytical procedure of depolymerization reaction of lignin


































































0 20 40 60 80 100

0 (BuOH)

1

4

10

(H2O)

H2OBuOH

(molar ratio)





Unidentified


Coke + Residue


0 5 10 15 20 25 30 35


Carboxylic esters

Carboxylate acids

Alcohol

Phenols0 (BuOH)

1

4

10

(H2O)

H2OBuOH

(molar ratio)



Table 1


Fig 2



BuOH phaseC-mol 99 93 73 100 99 96




BuOH phaseC-mol 99 74 31 95 46 21










ization of lignin
































study

























BuOH Phase

BuOH

OH

OO OH

O

OH

OO

OH

O

OH

O

O

O

Water

Phase



Esterification



CH

CH

OH

CH2

O

O

O

C2H

5

O

OH

O

CH3H3C

H2O+

Lignin

Further

depolymerization

Lignin OH

C2H5COOH

CH3H3C


CH2

C

OH

CH2

OH

O O

O







tions



























of guaiacol





0 20 40 60 80 100

H2O

BuOH

H2O

Benzene

H2O

EtOH

Solvent

species




Unidentified


Coke + Residue

Identified by GC


Table 2






(PressureMPa) (11) (41) (97) (23)



Reaction time=2 h


Timeh 05 2 4 8




473 673 8730

02

04

06

08

10

Temperature K

273

(a) OSL Pr

rawOSL Pr

523 K

473 K

623 K

573 K



0

02

04

06

08

10

473 673 873273

Temperature K

raw KL

KL derived


(b) KL














4 Conclusions















from lignin

Acknowledgments




Japan

0 20 40 60 80 100





Coke + Residue

0 (BuOH)

4

(H2O)

H2OBuOH

(molar ratio)



of OSL Pr

(BuOH phase)

Without catalyst

ZrO2 Al2O3 FeOX

ZrO2 Al2O3 FeOX



0 2 4 6 8 10

Alkyl phenol

Methoxy phenol

Phenol + Cresol

0 2 4 6 8 10



of KL

(BuOH phase)



Methoxy phenol

Phenol + Cresol







References


































































































0 20 40 60 80 100

0 (BuOH)

1

4

10

(H2O)

H2OBuOH

(molar ratio)





Unidentified


Coke + Residue


0 5 10 15 20 25 30 35


Carboxylic esters

Carboxylate acids

Alcohol

Phenols0 (BuOH)

1

4

10

(H2O)

H2OBuOH

(molar ratio)



Table 1


Fig 2



BuOH phaseC-mol 99 93 73 100 99 96




BuOH phaseC-mol 99 74 31 95 46 21










ization of lignin
































study

























BuOH Phase

BuOH

OH

OO OH

O

OH

OO

OH

O

OH

O

O

O

Water

Phase



Esterification



CH

CH

OH

CH2

O

O

O

C2H

5

O

OH

O

CH3H3C

H2O+

Lignin

Further

depolymerization

Lignin OH

C2H5COOH

CH3H3C


CH2

C

OH

CH2

OH

O O

O







tions



























of guaiacol





0 20 40 60 80 100

H2O

BuOH

H2O

Benzene

H2O

EtOH

Solvent

species




Unidentified


Coke + Residue

Identified by GC


Table 2






(PressureMPa) (11) (41) (97) (23)



Reaction time=2 h


Timeh 05 2 4 8




473 673 8730

02

04

06

08

10

Temperature K

273

(a) OSL Pr

rawOSL Pr

523 K

473 K

623 K

573 K



0

02

04

06

08

10

473 673 873273

Temperature K

raw KL

KL derived


(b) KL














4 Conclusions















from lignin

Acknowledgments




Japan

0 20 40 60 80 100





Coke + Residue

0 (BuOH)

4

(H2O)

H2OBuOH

(molar ratio)



of OSL Pr

(BuOH phase)

Without catalyst

ZrO2 Al2O3 FeOX

ZrO2 Al2O3 FeOX



0 2 4 6 8 10

Alkyl phenol

Methoxy phenol

Phenol + Cresol

0 2 4 6 8 10



of KL

(BuOH phase)



Methoxy phenol

Phenol + Cresol







References









































ization of lignin
































study

























BuOH Phase

BuOH

OH

OO OH

O

OH

OO

OH

O

OH

O

O

O

Water

Phase



Esterification



CH

CH

OH

CH2

O

O

O

C2H

5

O

OH

O

CH3H3C

H2O+

Lignin

Further

depolymerization

Lignin OH

C2H5COOH

CH3H3C


CH2

C

OH

CH2

OH

O O

O







tions



























of guaiacol





0 20 40 60 80 100

H2O

BuOH

H2O

Benzene

H2O

EtOH

Solvent

species




Unidentified


Coke + Residue

Identified by GC


Table 2






(PressureMPa) (11) (41) (97) (23)



Reaction time=2 h


Timeh 05 2 4 8




473 673 8730

02

04

06

08

10

Temperature K

273

(a) OSL Pr

rawOSL Pr

523 K

473 K

623 K

573 K



0

02

04

06

08

10

473 673 873273

Temperature K

raw KL

KL derived


(b) KL














4 Conclusions















from lignin

Acknowledgments




Japan

0 20 40 60 80 100





Coke + Residue

0 (BuOH)

4

(H2O)

H2OBuOH

(molar ratio)



of OSL Pr

(BuOH phase)

Without catalyst

ZrO2 Al2O3 FeOX

ZrO2 Al2O3 FeOX



0 2 4 6 8 10

Alkyl phenol

Methoxy phenol

Phenol + Cresol

0 2 4 6 8 10



of KL

(BuOH phase)



Methoxy phenol

Phenol + Cresol







References






































tions



























of guaiacol





0 20 40 60 80 100

H2O

BuOH

H2O

Benzene

H2O

EtOH

Solvent

species




Unidentified


Coke + Residue

Identified by GC


Table 2






(PressureMPa) (11) (41) (97) (23)



Reaction time=2 h


Timeh 05 2 4 8




473 673 8730

02

04

06

08

10

Temperature K

273

(a) OSL Pr

rawOSL Pr

523 K

473 K

623 K

573 K



0

02

04

06

08

10

473 673 873273

Temperature K

raw KL

KL derived


(b) KL














4 Conclusions















from lignin

Acknowledgments




Japan

0 20 40 60 80 100





Coke + Residue

0 (BuOH)

4

(H2O)

H2OBuOH

(molar ratio)



of OSL Pr

(BuOH phase)

Without catalyst

ZrO2 Al2O3 FeOX

ZrO2 Al2O3 FeOX



0 2 4 6 8 10

Alkyl phenol

Methoxy phenol

Phenol + Cresol

0 2 4 6 8 10



of KL

(BuOH phase)



Methoxy phenol

Phenol + Cresol







References










































4 Conclusions















from lignin

Acknowledgments




Japan

0 20 40 60 80 100





Coke + Residue

0 (BuOH)

4

(H2O)

H2OBuOH

(molar ratio)



of OSL Pr

(BuOH phase)

Without catalyst

ZrO2 Al2O3 FeOX

ZrO2 Al2O3 FeOX



0 2 4 6 8 10

Alkyl phenol

Methoxy phenol

Phenol + Cresol

0 2 4 6 8 10



of KL

(BuOH phase)



Methoxy phenol

Phenol + Cresol







References





































References



































feo production of phenols from lignin via depolymerization and catalytic cracking

Documents