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以γ-Al_2O_3,ZrO_2及其混合物为载体,制备了五种硫化的钼催化剂(KW-01-KW-05),并对其常压及加压下的甲烷化反应性能进行了研究。观察到反应活性按KW-05至KW-01的顺序递减,反应的稳定性则以相反的顺序递减。在1.5MPa下的活性比常压下的活性增加2—8倍,而稳定性与常压下的类似。对比反应产物中CO_2生成量,可以认为,CO在钼催化剂上的甲烷化反应包括如下两个步骤:(1)3H_2+CO→CH_4+H_2O;(2)CO+H_2O→CO_2+H_2。用激光拉曼光谱研究了上述催化剂的表面结构与反应前后的变化。硫化前钼在催化剂上呈单层分布,无体相MoO_3和钼酸盐生成,并和差热分析的结果一致。硫化后的催化剂经常压反应后,催化剂表面发生MoS_2聚集现象,而加压反应后MoS_2特征峰减弱。在加压反应后的含锆样品上有积炭产生。
Five kinds of sulfided molybdenum catalysts (KW-01-KW-05) were prepared by using γ-Al 2 O 3, ZrO 2 and their mixtures as carriers, and the methanation reaction under normal pressure and pressure was studied. It was observed that the reactivity decreased in the order of KW-05 to KW-01, and the stability of the reaction decreased in the reverse order. The activity at 1.5 MPa is 2-8 times greater than at normal pressure, and the stability is similar to that at atmospheric pressure. Comparing the amount of CO 2 produced in the reaction product, it can be considered that the methanation reaction of CO on the molybdenum catalyst includes the following two steps: (1) 3H 2 CO + CH 4 + H 2 O; CO 2 + H 2 O → CO 2 + H 2. The surface structure of the catalyst and the changes before and after the reaction were investigated by laser Raman spectroscopy. Pre-sulphided molybdenum monolayer on the catalyst distribution, the formation of bulk phase MoO_3 and molybdate, and differential thermal analysis of the results. After the vulcanization of the catalyst pressure reaction, the catalyst surface MoS_2 aggregation occurs, while the pressure response MoS_2 characteristic peak weakened. There is carbon deposition on the zirconium-containing sample after the pressure reaction.