Ni-W/Si-MCM-41加氢脱硫催化剂中Ni的助剂作用

ROLE OF Ni IN Ni-W/Si-MCM-41 HYDRODESULFURIZATION CATALYSTS

在中压固定床反应器上,以含质量分数0.2%～0.8%二苯并噻吩(DBT)的十氢萘溶液为模型化合物,考察了Ni-W/Si-MCM-41催化下的加氢脱硫反应(HDS)动力学.结果表明,HDS反应的表观活化能(EHDS)和氢解反应的表观活化能(EHYG)在Ni/W摩尔比为0.75时最小,而加氢反应的表观活化能(EHYD)则随Ni/W摩尔比的增加单调降低,表明在Ni-W/Si-MCM-41催化剂上加氢和氢解的活性中心不同.紫外/可见漫反射光谱(UV-Vis)和程序升温还原技术(TPR)表征的结果表明,Ni-W/Si-MCM-41的加氢活性中心可能与催化剂表面八面体配位的Ni物种有关,而氢解活性则与NiO-WO3混合物种的还原性能有一定对应关系.

The kinetics of hydrodesulfrization （HDS） of dibenzothiophene （DBT） catalyzed by Ni-W/Si-MCM-41 was studied by using a model mixture containing 0. 20%--0. 8% （mass fraction） DBT in decalin. The results indicated that Ni-W/Si-MCM-41 with the Ni/W molar ratio of 0.75 exhibited the lowest HDS apparent activation energy （EHDS） and hydrogenolysis apparent activation energy （EHYG）, whereas the apparent activation energy of hydrogenation reaction （EHYD） decreased with the increase of the Ni/W molar ratio, which suggested that the two reactions take place on different types of catalytic sites. It was further confirmed by the results of UV-Vis and TPR that the active site of hydrogenation was correlated with the octahedrally coordinated Ni species, while the hydrogenolysis activity of Ni-W was related with the reducibility of NiO-WO3 species.