Carbon Silica Composites‘2 different approaches’

A) Two step synthesis (CSM): - Carbon deposition in silica template material

B) One step synthesis: - Co-precipitation of silica and carbon source

Synthesis of composites: Partner 1 (Prof. B. Sels, Prof P.A. Jacobs)

In situ polymerisation of FA graphitic carbon T , inert atmosphere

Pyrolysis

Characterisation of composites: Partner 1 & 2 (Prof. Sels, Prof Jacobs // Prof. Hofkens)

CSM nanostructure research: 1) Raman spectroscopy 2) XRD analysis Hypothesis

Observation (HRTEM)

ID/IG size crystallites (length)La = 11 nm

Debye SherrerLc = 0,9 nm → 3 layers graphene

Sorption: Partner 8 & 1 (Prof. Baron, Prof. Denayer // Prof. Sels, Prof Jacobs)

zeolieten

Bipom

CSC

M41s MOF

de Clippel et al.Chemical Communications, 2009

(10.1039/b918864a)

• Molecular probing study of the composite’s pore system– Separation of linear and branched paraffins at low conc.

(pulse chromatography)– Separation of paraffin mixture at high conc. (breaktrough chromatography)– Capacity determination (gravimetric sorption)

Cis-3-hepteenCis-cyclo-octeen

Catalysis: - Shape selectivity: Epoxidation- Polarity Influence Carbon environment: Esterification- Bi-functional catalysts: conversion of dihydroxyaceton- Type & Strength Catalytic Sites: Dimerisation

Epoxidation ofcis-cyclo-octene / cis-3-heptene mixture (competitive experiment)

Critical Parameters: * Amount of carbon deoposition * Pyrolysis Temperature

Reagens selectivity

Catalytic Experiments: Partner 1 (Prof. Sels, Prof Jacobs)

/

1) Shape selectivity

Principle: Carbon acts as selective screen

2) Polarity carbon environment

3) Bi-functional catalysts

O

OH+ CH3OH

O

OCH3 + H2OH+

- Stable- Highly active - Carbon based Acidic Catalyst

Li Peng et al.Catalysis Today, 2009

(doi:10.1016/J.cattod.2009.07.066)

- Composite: 2 components different activation procedures - Example: * Sn grafting (SILICA): Lewis Acidic Sites * H2SO4 treatment (CARBON): Bronsted Acid sites

Weak BronstedAcid

Strong BronstedAcid

Lewis Acid

3) Strength catalytic site (Brönstedt Acid)

Strong Brönsted acid

Weak Brönsted acid

Unsaturated dimer

Saturated dimer

Acid strength of sulfonic acid groups: - Influenced by electron distribution (polyaromatic carbon backbone)- Controllable (# carbon, conditions H2SO4 treatment)

Catalyst Surface area

M² /g

Acid density mmol H+/g

Conversion (%) Selectivity for unsaturated dimers (%)

sugar catalyst

NR50

CBV-720

H2SO4

Si/C50/50-SO3H

< 5

-

780

-

428

0.7

0.8

1.0

20.4

0.33

trace

70

90

100

90

trace

58

36

2.3

91