加氢异构化催化剂的研究——-加氢功能的影响

以ZSM 22分子筛为酸性组分，制备了不同分子筛含量、不同金属负载量以及不同金属种类的加氢异构催化剂。采用XRD、氢氧滴定、N2吸附、吡啶吸附和SEM等表征工具对所用分子筛以及制备的催化剂进行了详细的表征。以正癸烷为模型化合物，考察了制备的催化剂的烷烃异构转化活性和选择性，并将获得的反应结果与表征数据相关联。结果表明，对于长链烷烃加氢异构反应，当加氢功能不足时，长链烷烃加氢/脱氢反应为控制步骤；为了制备双功能平衡的加氢异构催化剂，Pd负载量要高于Pt，但当双功能平衡后2种催化剂的异构反应行为一致。对于长链烷烃加氢异构反应，加氢中心与酸性中心之间的距离不是影响催化剂异构选择性的关键因素。

Investigation on the hydroisomerization Catalyst--The Effect of the Hydrogenation Function

Hydroisomerization catalysts with varied zeolite contents, different metal and loading were prepared using ZSM 22 as the acidic component. The catalysts were thoroughly characterized by various tools like XRD, hydrogen oxygen titration, N2 adsorption, pyridine adsorption and SEM. These catalysts were also investigated by the selectivity and activity of paraffin hydroisomerization transformation using decane as the model molecule and the obtained results were correlated to the characterization data. It is revealed that the paraffin hydrogenation/dehydrogenation is the controlling step during the paraffin hydroisomerization transformation if the hydrogenation capacity over a hydroisomerization catalyst is deficient. To prepare a hydroisomerization catalyst with the balance between the hydrogenation function and acid function, the loading of Pd needs to be more than the loading of Pt. But, the catalytic behaviors of hydroisomerization catalysts regardless of Pt or Pd being loaded are similar once the balance is approached. Moreover, it is demonstrated that the distance between hydrogenation sites and acidic sites is not a key factor for the hydroisomerization transformation of long chain paraffin.