柠檬酸引入方式对CoMo/TiO2-Al2O3催化剂加氢脱硫性能的影响

Effect of citric acid introduction methods on hydrodesulfurization performance of CoMo/TiO2-Al2O3 catalysts

采用改进溶胶-凝胶法制备的TiO2-Al2O3作复合载体,制备不同柠檬酸引入方式改性的CoMo/TiO2-Al2O3加氢脱硫催化剂。利用低温N2吸附-脱附、XRD、SEM和H2-TPR等对催化剂进行表征,并采用固定床反应器对催化剂加氢脱硫性能进行评价。结果表明,后处理法制备的催化剂比表面积相对较大,孔道结构较好,活性金属组分以无定形形态均匀分散在载体表面,一定程度上减弱了其与载体间的相互作用;该催化剂可以延缓Co硫化,并且络合生成较多易于硫化还原的Mo物种,利于MoS2在催化剂表面的堆叠,生成更多的Co-Mo-S(Ⅱ)活性相,因而相应的CoMo催化剂对噻吩加氢脱硫转化率显著提高。

TiO2-Al2O3 composite was prepared by improved sol-gel method.And the composite was employed to fabricate the CoMo/TiO2-Al2O3 hydrodesulfurization catalysts with different modification of citric acid.The as-synthesized catalysts were systematically characterized by means of N2 adsorption-desorption,XRD,SEM and H 2 -TPR,and evaluated hydrodesulfurization performance in fixed-bad reactor.The results indicated that the catalyst prepared by the post-treatment method possessed higher surface area,better pore structure than the other catalysts.And the active metal components in amorphous form were uniformly dispersed on the surface of the carrier,which would weaken the interaction between active metal components and carrier.In addition,this catalyst exhibited ability of delaying sulfurization of cobalt and generating more easily sulfurized molybdenum species,which would facilitate MoS2 to stack on the surface of the catalyst to form more Co-Mo-S(Ⅱ) active phase.Thus conversion of thiophene in hydrogenation desulfurization over the corresponding CoMo catalyst has increased dramatically.