The synthesis and testing of thin film ZSM-5 catalysts |
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Authors: | Jonas Hedlund Olov Öhrman Eric van Steen Sifiso Sibya |
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Affiliation: | a Division of Chemical Technology, Luleå University of Technology, Luleå S 97187, Sweden b Catalysis Research Unit, Department of Chemical Engineering, University of Cape Town, Private Bag, Rondebosch 7700, Cape Town, South Africa |
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Abstract: | The synthesis and catalytic testing of thin ZSM-5 films on glass and alumina beads is described. The thickness of the ZSM-5 films was controlled to 150, 350, 800 and . The samples were characterised by SEM, gas adsorption and p-xylene isomerisation and 1,3,5-tri-isopropyl benzene cracking test reactions. A reaction-diffusion model adequately described the p-xylene isomerisation data. Estimates of model parameters were obtained by fitting the model to the experimental data. In both cases, the reaction rate constant increased with increasing film thickness. The xylene reaction data showed that secondary reaction products increased as expected with increasing diffusion limitations, but the increase was less than that predicted by the variation of thickness only. The trends in the reaction data could be explained by more defects in the thicker films and/or partial poisoning of the zeolite by mobile support cations in thinner films and/or orientation effects. |
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Keywords: | Catalysis Diffusion Films Modelling Synthesis Zeolites |
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