活化温度对NiW/Al_2O_3催化剂中金属-载体相互作用的影响

考察了活化温度对NiW/Al_2O_3催化剂4,6-二甲基二苯并噻吩加氢脱硫活性和金属-载体相互作用的影响。研究结果表明,350～400℃是催化剂获得高脱硫活性的适宜活化温度,在该温度下对催化剂进行活化有利于金属.载体之间保持适度的相互作用,并促进W金属的硫化。高温活化(450℃)会导致Ni与氧化铝载体的相互作用增强,生成尖晶石物相,破坏Ni-W-O混合相物种,使金属W不易硫化,导致催化剂活性下降。

INFLUENCE OF ACTIVATION TEMPERATURE ON METAL-SUPPORT INTERACTION IN NiW/Al2O3 CATALYST

The influence of activation temperature during the preparation of NiW/Al2O3 catalysts on the metal-support interaction was studied. Test results show that the activation temperature has significant effect on the hydrodesulfurization (HDS) activity of the catalyst when using 4,6-dimethyldibenzothiophene as model compound; the optimum activation temperature is in the range of 350℃ to 400℃, catalysts activated in this temperature range exhibited high HDS activity due to the moderate metal-support interaction and a promotion to the sulfidation of W species, which are well supported by the results of UV-Vis, H2-TPR and XPS characterization. High temperature (>450℃) activation may cause a strong metal–support interaction, which leads to the formation of Ni-Al spinel and the decomposition of Ni-W-O mixture, and that might further suppress the sulfidation of W species, as a result, the catalyst activity is reduced.