载体对Pd和Pt催化剂加氢脱硫反应性能的影响

以质量分数为0.8%的二苯并噻吩(DBT)的十氢萘溶液为模型化合物,考察了SiO_2,Si-MCM-41和Al-MCM-41负载的Pd和Pt催化剂加氢脱硫(HDs)反应性能,并与传统的γ-Al_2O_3负载的催化剂进行了对比.反应结果表明,负载型Pd和Pt催化剂在DBT的HDS反应中表现出不同的反应特点.Pd催化剂具有较高的加氢反应路径(HYD)选择性,而Pt催化剂则表现出较高的直接脱硫路径(DDS)选择性.载体结构和表面酸性显著影响其负载的Pd和Pt贵金属催化剂的HDS活性以及HYD选择性和稳定性.提高载体比表面积和酸性有利于提高负载型贵金属催化剂HYD选择性.Al-MCM-41具有规整的介孔结构、较高比表面积和较强酸性,其负载的Pd和Pt催化剂表现出较高的HYD选择性和稳定性.研究还发现,催化剂加氢裂化反应活性随载体酸性的提高而增加.

Effect of Support on the Hydrodesulfurization Performances of Supported Pd and Pt Cstalysts

The hydrodesulfurization (HDS) performances of Pd and Pt supported on SiO_2,Si-MCM-41, and Al-MCM-41 were investigated using a modal fuel containing 0.80% mass fraction dibenzothiophene (DBT) in decalin, and were compared with that over their γ-Al_2O_3 supported counterparts.The HDS results indicated that the supported Pd and Pt catalysts showed different HDS performances.The supported Pd catalysts exhibited high hydrogenation pathway (HYD) selectivity,whereas the supported Pt catalysts showed high direct desulfurization pathway (DDS) selectivity.The behavior of the supported Pd and Pt catalysts was significantly influenced by structure and acidity of the support.The HYD selectivity of the supported noble metal catalysts could be enhanced by increasing the acidity and the surface area of the support.Al-MCM-41 possessed regular mesoporous pore structure, high surface area and relatively strong acidity, and thus high HYD selectivity and stability were observed for Pd and Pt supported on Al-MCM-41.The results also showed that the hydroeracking activity of the catalysts can be improved by increasing the acidity of the support.