Predicting the Effect of Drying on Supported Coimpregnation Catalysts

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• 作者：Azzeddine Lekhal ; Johannes G. Khinast ; and Benjamin J. Glasser
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2001
• 出版时间：September 5, 2001
• 年：2001
• 卷：40
• 期：18
• 页码：3989 - 3999
• 全文大小：149K
• 年卷期：v.40,no.18(September 5, 2001)
• ISSN：1520-5045

文摘

In this paper, a model was developed to describe the catalyst redistribution that occurs duringdrying of a coimpregnation catalyst. The model takes into account convective flow, catalyst andcoimpregnant diffusion, adsorption on the support, and transport in the gas phase. For lowcatalyst adsorption capacity and low initial coimpregnant concentrations, the system behavesin a manner similar to systems without a coimpregnant. At higher coimpregnant concentrationwhen the coimpregnant has the higher adsorption constant, the catalyst faces strong competitionfor adsorption sites at the external surface. It therefore migrates toward the center where freesites are available. If the catalyst has the higher adsorption constant, it adsorbs preferentiallyat the surface, and the coimpregnant hinders the back-diffusion of the catalyst. This can lead torather sharp egg-shell profiles. Finally, we discuss how to develop a drying strategy that willlead to a desired catalyst profile.