K_2O对Co-Mo/MCM-41催化剂加氢脱硫性能的影响

EFFECT OF K_2O ON HYDRODESULFURIZATION PERFORMANCE OF Co-Mo/MCM-41

分别采用分步浸渍法和共浸渍法将K2O引入Co-Mo/MCM-41催化剂的前驱体中,制得的催化剂分别记作K-Co Mo/MCM-41和KCo Mo/MCM-41,并以质量分数0.8%二苯并噻吩(DBT)的十氢萘溶液作模型化合物,考察了3种硫化物催化剂对其加氢脱硫(HDS)反应的催化性能。采用XRD、UV-Vis和TPR分析手段对所得的催化剂进行了表征。结果表明,采用共浸渍法引入K2O,不仅破坏了载体全硅MCM-41的结构,还降低了Co-Mo/MCM-41催化剂中八面体配位的Mo物种含量;采用分步浸渍法将K2O引入Co-Mo/MCM-41前驱体中,对催化剂中物种的分布和配位状态影响不大,但抑制了Co-Mo/MCM-41前驱体的还原。DBT的脱硫路径有直接脱硫(DDS)和加氢脱硫(HYD)两条路径,在Co-Mo/MCM-41硫化物催化剂上,主要通过DDS路径脱硫。KCo Mo/MCM-41对DBT的DDS和HYD的催化活性都低于Co-Mo/MCM-41,因而总的DBT HDS反应活性也较低。而采用分步浸渍法引入K2O对Co-Mo/MCM-41总的DBT HDS催化活性影响不大,但提高了Co-Mo/MCM-41对DDS路径的催化活性,同时抑制了其对HYD路径的催化活性,降低了反应过程中氢气的消耗。

K2O was introduced to Co-Mo/MCM 41 catalyst precursor by a consecutive impregnation method and a co impregnation method. The obtained catalysts were denoted as K-CoMo/MCM-41 and KCoMo/MCM-41, respectively, and characterized by means of XRD, UV-Vis and TPR. The hydrodesulfurization （HDS） performances of the three sulfide catalysts were studied by using a model fuel containing 0.8% （mass fraction） DBT in decalin. The results indicated that the introduction of K2O to Co-Mo/MCM-41 by co-impregnation method not only destroyed the structure of MCM-41, but also led to a decrease in the octahedrally coordinated Mo species. Nevertheless, neither the distributions nor the coordination states of the active species were affected by the introduction of K2O with the consecutive impregnation method, except that the reducibility of K-CoMo/MCM-41 precursor was decreased. The HDS of DBT predominately took the route of direct desulfurization （DDS） over the Co-Mo/MCM-41 sulfides. KCoMo/MCM-41 showed lower DDS catalytic activity and hydrogenation （HYD） catalytic activity than CoMo/MCM-41, and therefore exhibited lower overall catalytic activity in HDS of DBT. However, the introduction of K2O to CoMo/MCM-41 by the consecutive impregnation method had little influence on the overall HDS catalytic activity of the CoMo/MCM-41catalyst, but led to an enhancement of catalytic activity in the DDS pathway and a decrease of catalytic activity in the HYD pathway, and therefore a decrease of the H2 consumption in the HDS reaction.