烷基化催化剂表面酸性及催化性能的动力学研究

在确定关联升温速率、脱附峰温和脱附峰覆盖率的程序升温脱附动力学模型的基础上，通过TPD实验和模型参数估值，建立了表征催化剂酸密度、酸强度及强度分布情况的方法。研究表明，随着活化温度的提高，固体酸催化剂表面酸中心强度分布先变宽后趋于均匀，350?℃活化催化剂的强度分布最宽；催化剂表面酸强度和酸密度随活化温度提高均呈先增大后降低、分别在350 ℃和250 ℃活化温度达到极大值的变化规律。催化剂酸性与催化性能关联的结果表明，随着活化温度的提高，烷基化反应速率常数与总脱附量的变化趋势相同，而催化剂失活速率常数与脱附活化能变化趋势相同；催化剂活性稳定性随其酸强度的增大而变差，催化剂活性与催化剂酸量和酸强度有关。

Kinetic study of surface acidity and catalytic performance of alkylation catalyst

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.