柠檬酸对CoMo/Al_2O_3催化剂中助剂作用的影响

在一系列不同金属摩尔比n(Co)/n(Co+Mo)]的CoMo/Al2O3催化剂制备过程中引入柠檬酸,考察了柠檬酸对CoMo催化剂中助剂作用的影响,并采用BET,XRD,XPS,HRTEM等手段进行表征。结果表明:柠檬酸可以提高助剂Co和主剂Mo在载体表面的分散性,使Co对MoS2的助剂作用增强,这种促进作用在较高金属摩尔比时更加明显;在4,6-二甲基二苯并噻吩加氢脱硫反应中,催化剂的加氢脱硫活性均随助剂含量的增加表现出先增后减的趋势,且在金属摩尔比为0.3时达到最高;添加柠檬酸后催化剂的脱硫活性提高,且在较高金属摩尔比时活性提高更为明显。

INFLUENCE OF CITRIC ACID ON PROMOTER ROLE IN CoMo/Al2O3 CATALYST

A series of CoMo/Al2O3 catalysts with different metal ratio（Co/(Co+Mo)） were prepared using citric acid (CA) as a chelating agent by stepwise impregnation method. The effect of CA on the role of promoter was studied and the prepared CoMo/Al2O3 catalysts were characterized by BET，XRD，XPS and HRTEM techniques. The results show that CA can increase the dispersion of Co and Mo, and enhance the promotion role of the promoter，especially at higher metal ratio. The activity of 4, 6-dimethyldibenzothiophene hydrodesulfurization show a trend of increase first than decrease as increasing the metal ratio, and reaches its highest value at the ratio around 0.3. Meanwhile, it is apparent that the catalytic activity obtains an important enhancement when the catalysts are prepared in presence of CA，especially at higher metal ratio.