Synthesis, characterisation and engineering of thin films of ZSM-5 on alumina, quartz and sand supports
type: CreativeWork
description: Zeolite films supported on inert material are a novel type of catalyst that could provide interesting activity and selectivity properties. Such materials will see application in catalytic distillation as reactive packings and in novel low pressure drop catalytic reactors. This thesis studies the physical and reactive properties of thin ZSM-5 films supported on alumina, quartz and sand packings. The objective of this work is to evaluate the intrinsic catalytic properties of these materials by estimating the reaction-diffusion model parameters from the results of the tri-isopropylbenzene (TIPB) cracking and para-xylene (pX) isomerization probe reactions. These intrinsic model parameters are then correlated with respect to the physical analysis of the zeolite films. It is postulated that the zeolite films on all supports would be smooth and homogeneous, the model parameters would be independent of film thickness while the selectivity and activity would depend strongly on film thickness. Zeolite films were prepared on 3 supports (3mm quartz and alumina beads, and 0.2mm sand particles) using the seed film method. The samples are characterised SEM, 12 adsorption, XPS, EDX, and ICP-AES. SEM analysis indicated that four film thicknesses of 150, 350, 800, 2300 nm are prepared on each support. Results indicate that only the Quartz supported zeolite films could be characterised as smooth and homogeneous. The sand supported zeolite was subject to agglomeration during preparation. The alumina support contained surface pores and mobile cations which caused non-uniform film growth and deactivated the active sites during catalyst pre-treatment, respectively. The TIPB reaction, which estimated only the external activity of the catalyst, showed that, for smooth inert films (quartz, sand) and within experimental error, the rate constants remained constant with film thickness. In the case of alumina supports, the activity increased with increasing film thickness, conforming to a diffus…
abstract: Zeolite films supported on inert material are a novel type of catalyst that could provide interesting activity and selectivity properties. Such materials will see application in catalytic distillation as reactive packings and in novel low pressure drop catalytic reactors. This thesis studies the physical and reactive properties of thin ZSM-5 films supported on alumina, quartz and sand packings. The objective of this work is to evaluate the intrinsic catalytic properties of these materials by estimating the reaction-diffusion model parameters from the results of the tri-isopropylbenzene (TIPB) cracking and para-xylene (pX) isomerization probe reactions. These intrinsic model parameters are then correlated with respect to the physical analysis of the zeolite films. It is postulated that the zeolite films on all supports would be smooth and homogeneous, the model parameters would be independent of film thickness while the selectivity and activity would depend strongly on film thickness. Zeolite films were prepared on 3 supports (3mm quartz and alumina beads, and 0.2mm sand particles) using the seed film method. The samples are characterised SEM, 12 adsorption, XPS, EDX, and ICP-AES. SEM analysis indicated that four film thicknesses of 150, 350, 800, 2300 nm are prepared on each support. Results indicate that only the Quartz supported zeolite films could be characterised as smooth and homogeneous. The sand supported zeolite was subject to agglomeration during preparation. The alumina support contained surface pores and mobile cations which caused non-uniform film growth and deactivated the active sites during catalyst pre-treatment, respectively. The TIPB reaction, which estimated only the external activity of the catalyst, showed that, for smooth inert films (quartz, sand) and within experimental error, the rate constants remained constant with film thickness. In the case of alumina supports, the activity increased with increasing film thickness, conforming to a diffus…
author: Msimang, Velaphi Zakhele
language: eng
date published: 2005
date modified: 2026-07-22T22:23:34Z
provider: University of Cape Town
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Department of Chemical Engineering

PropertyValue
property ID: Handle
value: http://hdl.handle.net/11427/6733