Al_2O_3作为粘结剂对Pt/HZSM-5的酸性质和催化性能的影响

EFFECT OF ALUMINA AS BINDER ON THE ACIDITY AND CATALYTIC PERFORMANCE OF Pt/HZSM-5

本文以Al_2O_3为粘结剂,制备了具有较好催化活性、选择性和强度的二甲苯异构化催化剂Pt/HZSM-5-Al_2O_3。研究了Al_2O_3的含量、制备过程中HNO_3浓度以及热处理的方式等对催化剂的强度、酸性质和催化性能的影响,得到了制备该种催化剂的最佳条件。本文还用NH_3-TPD方法和红外光谱研究了Al_2O_3含量对催化剂酸性质的影响。考察了催化剂的活性、选择性和稳定性。并与不加Al_2O_3的Pt/HZSM-5进行了比较,得到了对发展二甲苯异构化工艺有益的信息。

A new catalyst, Pt/HZSM-5/Al_2O_3, for xylene isomerization have been prepared with the use of Al_2O_3 as binder.This catalyst has better activity, selectivity, stability and strength than the currently used ones. The effects of alumina content, the concentration of HNO_3 used during the preparation and the thermal treatment procedure on the strength, acidic properties and catalytic performance of the catalyst are studied. The optimal conditions of preparation thus observed are: alumina content, 35% ; HNO_3 concentration, 3 mol/L; and thermal treatment, stepwise heating. The effect of alumina content on acidity of catalyst is also investigated by means of NH_3-TPD and IR spectrometry. The activity, selectivity and stability are also examined and compared with Pt/HZSM-5 that has no Al_2O_3 binder. The information obtained by this study might be benificial to the development of xylene isomerization process.