TiO_2-Al_2O_3复合载体焙烧温度对Co-Mo加氢脱硫催化剂性能的影响

EFFECT OF THE CALCINATION TEMPERATURE OF TiO_2-Al_2O_3 COMPLEX SUPPORT ON THE CATALYTIC PERFORMANCE OF Co-Mo HYDRODESULFURIZATION CATALYST

采用混捏法制备纳米介孔TiO2-Al2O3复合载体,考察载体焙烧温度对负载型Co-Mo双金属加氢脱硫催化剂性能的影响,并采用N2物理吸附、X射线衍射和吸附吡啶红外光谱技术对复合载体及催化剂进行表征。结果表明,不同温度焙烧的复合载体都具有介孔结构;随焙烧温度的升高,催化剂的比表面积和孔体积减小,平均孔径增大;催化剂中TiO2的平均晶粒尺寸属纳米级且随焙烧温度的升高而增大;复合载体中Al2O3的存在提高了TiO2的晶型转变温度;不同温度焙烧的复合载体表面均主要为L酸中心而几乎没有B酸中心。在微型固定床反应器上对制备的Co-Mo/TiO2-Al2O3催化剂进行了评价,结果表明,载体经适宜温度焙烧后所得催化剂具有良好的加氢脱硫活性和选择性。

Nano-mesoporous TiO2-Al2O3 complex supports were prepared by kneading method. The influence of the calcination temperature of support on the catalytic performance of Co-Mo catalyst was studied. The prepared catalyst samples were characterized by means of N2 adsorption, X ray diffraction and pyridine adsorption FT-IR. The results indicated that the complex supports calcined at various temperatures were all mesoporous materials with mainly Lewis acid sites. With the increase of support calcined temperature,the specific surface area and pore volume of the catalyst decreased and the average pore diameter increased. In the catalyst the TiO2 particles existed as nanoparticles and its particle size increased with the increase of calcination temperature. The presence of Al2O3 in the complex support could significantly increase the transformation temperature of TiO2 crystal. The prepared catalysts were evaluated in a 10 mL fixed-bed reactor and the test results showed that the catalysts prepared with supports calcined at suitable temperature exhibited high hydrodesulfurization activity and selectivity.