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Carbon Silica Composites ‘2 different approaches’ PowerPoint Presentation
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Carbon Silica Composites ‘2 different approaches’

Carbon Silica Composites ‘2 different approaches’

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Carbon Silica Composites ‘2 different approaches’

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  1. A) Two step synthesis (CSM): - Carbon deposition in silica template material Carbon Silica Composites‘2 different approaches’ Pyrolysis In situ polymerisation of FA graphitic carbon T  , inert atmosphere B) One step synthesis: - Co-precipitation of silica and carbon source Synthesis of composites: Partner 1 (Prof. B. Sels, Prof P.A. Jacobs)

  2. CSM nanostructure research: 1) Raman spectroscopy 2) XRD analysis Hypothesis Debye Sherrer Lc = 0,9 nm → 3 layers graphene Observation (HRTEM) ID/IG  size crystallites (length) La = 11 nm Characterisation of composites: Partner 1 & 2 (Prof. Sels, Prof Jacobs // Prof. Hofkens)

  3. M41s • 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) MOF Bipom CSC zeolieten de Clippel et al. Chemical Communications, 2009 (10.1039/b918864a) Sorption: Partner 8 & 1 (Prof. Baron, Prof. Denayer // Prof. Sels, Prof Jacobs)

  4. Catalysis: • - Shape selectivity: Epoxidation • - Polarity Influence Carbon environment: Esterification • - Bi-functional catalysts: conversion of dihydroxyaceton • - Type & Strength Catalytic Sites: Dimerisation 1) Shape selectivity Epoxidation of cis-cyclo-octene / cis-3-heptene mixture (competitive experiment) Reagens selectivity Principle: Carbon acts as selective screen Critical Parameters: * Amount of carbon deoposition * Pyrolysis Temperature Cis-cyclo-octeen Cis-3-hepteen / Catalytic Experiments: Partner 1 (Prof. Sels, Prof Jacobs)

  5. 2) Polarity carbon environment - Stable - Highly active - Carbon based Acidic Catalyst Li Peng et al. Catalysis Today, 2009 (doi:10.1016/J.cattod.2009.07.066) 3) Bi-functional catalysts - Composite: 2 components  different activation procedures - Example: * Sn grafting (SILICA): Lewis Acidic Sites * H2SO4 treatment (CARBON): Bronsted Acid sites Weak Bronsted Acid Lewis Acid Strong Bronsted Acid

  6. 3) Strength catalytic site (Brönstedt Acid) Weak Brönsted acid Strong Brönsted acid Unsaturated dimer Saturated dimer Acid strength of sulfonic acid groups: - Influenced by electron distribution (polyaromatic carbon backbone) - Controllable (# carbon, conditions H2SO4 treatment)