SYNTHESIS AND CHARACTERISATION OF

MANGANESE MANGANESE FUNCTIONALIZED SILICA

AEROGELS

Tatjana KobalTatjana Kobal

Material characterization Material characterization graduate study graduate study programmeprogramme

POROUS MATERIALSPOROUS MATERIALS

Porous materials have highly developed internal surface area that can be used to perform specific function

Almost all solids are porous except for ceramics fired at extremely high temperatures

Non-porous solid Porous solid

Low specific surface areaLow specific pore volume

High specific surface areaHigh specific pore volume

Porous material are classified according to the size of pores: material with pores less than 2 nm are called micropores, p pmaterials with pores between 2 and 50 nm are called mesopores, and material with pores greater than 50 nm are macrospores

APPLICATION OF POROUS MATERIALSMATERIALS

CATALYSTS

HEAT MOLECULAR

SIEVES STORAGE

APPLICATION

ELECTROCEMICAL STORAGE

ADSORBENTS FOR GAS

SOL-GEL SYNTHESISThe sol-gel process is a wet-chemical technique used for preparation of versatile materials at lower temperatures.

Typical materials prepared with classical sol gel are pure orTypical materials prepared with classical sol-gel are pure or multicomponent metal oxides or related hybrid inorganic-organic materials. Most typical precursors are metal alkoxides (M(OR)x).

The sol-gel method is based on the hydrolysis and condensation reactions which leads to formation of the extended 3D network (gel) by forming the -M-O-M- links

hydrolysis

condensationreaction

Preparation of materials in a ide ariet of formswide variety of forms:

ultra-fine powdersfibers solidssolids xerogelsaerogels thin filmsthin films bulk materials

The technique is cheap and materials are prepared atmaterials are prepared at relatively low or even ambient temperatures.

BASIC CHARATERIZATIONBASIC CHARATERIZATION

TG

NITROGEN

TECHNIQUES

NITROGENPHYSIOSORPTION

TECHNIQUES

XRD

SEM+EDAX

RECENT RESEARCHRECENT RESEARCH

Porous silicates are used as catalytic supports in chemical reactions

Manganese is one of the most intensively used elements in homogeneous oxidation catalysis

It was shown recently that manganese-functionalized porous silicate catalyst (named KIL-2, synthesised at Kemijski Inštitut Ljubljana) is a highly promising heterogeneous catalytic system in catalytic water cleaning N N Tušar A Ristić G Mali M Mazaj I Arčon D Arčon V Kaučič N Z LogarN.N.Tušar, A.Ristić, G.Mali, M.Mazaj, I.Arčon, D.Arčon, V.Kaučič, N.Z. Logar, Chem.Eur.J., 2010, 16, 5783-5793

However, MnKIL-2 is not recycable, because of the manganese leaching from the silicate supportthe silicate support.

The problem could be solved using aerogels as silicate supports for manganese.

CASE STUDY FOR SYNTHESIS of manganese functionalized porous silicate MnKIL 2functionalized porous silicate MnKIL-2

REACTION GEL IN ALCALINE CONDITIONS1 TEOS : 0,5 TEA : 0,1 TEAOH : 11 H2O

solvothermaltreatmentethanol

first step second step

thermal treatmentcalcination at 500 oC in the air flow

CASE STUDY FOR CHARACTERIZATIONCHARACTERIZATION

of manganese functionalized porous ili t M KIL 2silicate MnKIL-2

Basic structure characterization:Basic structure characterization:XRD, SEM and nitrogen physisorption

Characterization of local enviranment of manganese are: XAS (EXAFS, XANES).

SCANNING ELECTRON MICROSCOPE (SEM)MICROSCOPE (SEM)

SEM micrograph suggests that the main type of porosity in the sample is the so calledin the sample is the so-called interparticle mesoporosity

Figure 1. SEM micrograph of the template‐freeMn/KIL‐2.

X-RAY POWDER DIFFRACTION (XRD)

(XRD)

150000

200000

ity 600

800

1000

ty

sampleholder

0

50000

100000

Inte

nsi

0

200

400

Inte

nsit

1 2 3 4 5

0

2θ (ο)

10 20 30 40 50 60 70 80-200

2θ (ο)

Figure 2: XRD patterns of the template-free sample of Mn/KIL-2: a) theleft figure shown: at low angles in the 2θ range from 0 3° to 5° and rightleft figure shown: at low angles in the 2θ range from 0.3 to 5 and rightfigure at high angles in the 2θ range from 5° to 80°.

NITROGEN PHYSISORPTION1600

NITROGEN PHYSISORPTION

1200

1400

0.08

0.10

0.12

gnm

)

g)

Figure 3. Nitrogen sorptionisotherm with pore sizedi ib i (I ) f

800

1000

0.02

0.04

0.06

PSD

(cm

3 /g

bed

(cm

3 /STP

g

distribution curve (Inset) ofMn/KIL-2.

400

6005 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

0.00

Pore Size (nm)

Vol

ume

Ads

or

200

400

0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,00

Relative Pressure (P/Po)

AEROGELSHYSTORYHYSTORY

Steven S. Kistler prepare aerogels in 1931

In the 70th years of the previous century, it was used for storing oxygen and rocket fuel

PROPERTIESPROPERTIES

extremely high porosityextremely high porositylarge area of low densitylow density high optical conductivity low thermal conductivity low dielectric constant

SYNTHESISSYNTHESIS

• Mn functionalized Aerogel gprepared by the sol-gel synthesis

Metal alkoxide

Acid+H20/EtOH

Wet gel

Dry gel

CHARACTERIZATION

Basic structure characterization are:

CHARACTERIZATION

Basic structure characterization are: XRD,SEM and nitrogen physiosorption

Characterization of local environment of TEM EPRmanganese are: TEM, EPR

2006

ACKNOWLEDGEMENTS

National Institute of Chemistry, Slovenia

Laboratory for inorganic chemistry and technology,National institute of Chemistry,Ljubljana, SLOVENIA

Prof. dr. Nataša Novak Tušardr. Alenka Ristić

Ljubljana, SLOVENIA

dr. Alenka Ristić