【摘要】 本文目的在于研究稀土铈对钼酸铋的丙烯选择氧化影响.不同比例的催化剂呈现了比较复杂的动力学行为.随着催化剂组成变化,氧反应级数可由零级经过0.5级直至无一定反应级数,对丙烯的反应级数也随组成改变有很大变化.为解释这一现象,本文提出了统一反应机理,即随着催化剂组成变化,催化剂表面活性中心由晶格氧经历吸附原子态氧至吸附分子态氧变化.通过X光、红外及其它实验结果表明,预期这样的活性中心变化是由于铈的存在形成了钼酸铈晶相,破坏了钼酸铋晶体形成而促使钼酸铋更加分散缘故.更多还原

【Abstract】 The influence of Ce on the selective oxidation of propylene catalyzed by bismuth molybdate was studied. Kinetic results show that different Bi-Ce ratios of the catalyst exhibit comparatively complex behaviors. Following the change of the composition of the catalyst, the order of the oxidation changes from zero through 0.5 to no definite order and simultaneously the order for propylene also undergoes a great ohange as the composition of catalyst changes. To explain this phenomenon, an unified reaction mechanism is suggested so that as the composition of the catalyst changes the surface active center changes from the lattice oxygen, through the atomic state, to molecular state. Through X-ray, infrared and other studies, it is shown that, such a ohange of surface active centers is due to the formation of cerium molybdate phase which spoiled the formation of lattice of bismuth molybdate, thus making the latter more dispersed.更多还原