Application of the transformation of 1,2,4-Trimethylbenzene to monitor the chemical vapour deposition of Tetraethoxysilane over ZSM-5

• Main Author: Röger, Hans Peter
• Other Authors: Möller, Klaus
• Format: Doctoral Thesis
• Language: English
• Published: University of Cape Town 2016
• Subjects: Chemical Engineering
• Online Access: http://hdl.handle.net/11427/19813

The present work reports an improved chemical vapour deposition (CVD) technique using low temperature, tetraethoxysilane (TEOS) and repeated CVD-calcination cycles. This results in a better control of the external surface activity and the pore mouth size of ZSM-5. In search for effective characterisation tools and a model reaction which involves molecules which are critical in size relative to the size of the ZSM-5 channels, the transformation of 1,2,4-trimethylbenzene (1,2,4-TMB) was investigated with respect to the reaction network, the role of the micropore space and the response to CVD treatments and Silicalite I coating. A generalised interpretation of the effect of modifications of the external surface activity and the pore mouth size on activity and shape selectivity of zeolites is proposed.