烷基化催化剂表面酸性及催化性能的动力学研究

The objective of this paper is to study the surface acidity and catalytic performance of the catalyst for alkylation with kinetic methods. A temperature-programmed desorption (TPD) kinetic model related with heating rate, temperature and n-Propylamine overlay fraction of catalyst surface acid sites at maximum rate of desorption was determined, and a method characterizing acid density, acid strength and the distribution extent of acid strength was developed. The TPD results indicate that the distribution extent of catalyst surface acid sites broadens firstly and then restricts with increasing catalyst activation temperature, which reaches the broadest at activation temperature of 350 ℃. It was revealed that the acid density and acid strength of the catalyst acid sites change from rise to drop with increase of the catalyst activation temperature and approach to maximum at 250 ℃ and 350 ℃, respectively. The relationship between the acidity and catalytic performance of catalyst exhibits that the stronger acid strength of catalyst is, the larger rate constant of catalyst deactivation is and that the alkylation rate constant is affected by the acid density and acid strength of catalyst. The stability of the catalyst could be improved by increasing the acid density and reducing the acid strength of the catalyst.