用微波技术制备NiW /TiO_2-Al_2O_3加氢脱硫催化剂

Preparation of NiW/TiO_2-Al_2O_3 Hydrodesulfurization Catalyst with Microwave Technique

采用微波技术制备了NiW /TiO2 Al2 O3 加氢脱硫催化剂,并用NH3 TPD ,Py FT IR ,TPR和TPS(程序升温硫化)对催化剂进行了表征;以噻吩为模型化合物,在中压固定床微反装置上考察了催化剂的加氢脱硫性能.结果表明,在w(TiO2 ) =15 %的催化剂样品中,微波处理的催化剂的活性比常规催化剂高.微波处理改变了载体和催化剂表面的酸性质,催化剂样品表面的强酸酸量减少,弱酸和中强酸酸量增加.微波处理的催化剂的还原性能和硫化性能均好于常规法制备的催化剂.这可能是微波技术制备的催化剂具有较高加氢脱硫活性的原因.

The NiW/TiO_2-Al_2O_3 catalyst samples were prepared by conventional drying method (CON-Cat) and by microwave irradiation method (MW-Cat and MW-Cat1). The catalyst samples were characterized with NH_3-temperature-programmed desorption, Py-FT-IR, temperature-programmed reduction, and temperature-programmed sulfurization techniques. The hydrodesulfurization (HDS) reactivity of thiophene over them was studied in a fixed-bed microreactor. The thiophene conversion over MW-Cat increased from 70.9% at 16 h to 71.8% at 19 h, while the thiophene conversion over MW-Cat1 kept to 71% after 17 h and then increased very slowly. The HDS reactivity over CON-Cat increased slowly after 15 h and the thiophene conversion increased from 63.3% at 15 h to 69.4% at 19 h. The activity difference between CON-Cat and MW-Cat was due to the different sulfidation performance. MW-Cat or MW-Cat1 could be sulfided to some extent by using shorter time than CON-Cat. The surface acidic properties of MW-Cat and MW-Cat1 were changed with microwave irradiation power and time. The amounts of weak and medium acid sites in MW-Cat and MW-Cat1 increased, while that of strong acid sites decreased. The strength order of weak and medium acids was MW-Cat<MW-Cat1<CON-Cat. MW-Cat and MW-Cat1 were favorable for their sulfurization and had higher activity than CON-Cat because more active species were formed in MW-Cat and MW-Cat1 with microwave irradiation. MW-Cat and MW-Cat1 were more favorable for their reduction than CON-Cat.