【摘要】 在石油化工催化反应中,作为催化剂的低交换度的CuNaX分子筛,在反应过程中经常发生掉铜现象。我们应用多晶X-射线衍射方法,测定了三个具有不同吸附水量的CuNaX分子筛的结构,并用Rietveld方法进行了修正。从结构测定结果发现,随着吸附水量的增大,Cu²⁺离子发生迁移,在饱和吸水状态下,Cu²⁺离子迁移入超笼。随着吸附水的减少,Cu²⁺离子又可逆地返回S（Ⅱ）位置。催化剂理想的活性中心应为定位于S（Ⅱ）位置上的Cu²⁺离子。掉铜的机理是由于迁移至超笼的Cu²⁺离子失去了骨架氧原子的制约,与反应物生成中间产物而流失。因此在反应前对分子筛进行焙烧予处理,以及对反应物进行脱水,均可阻止铜的流失,延长催化剂寿命。更多还原

【Abstract】 "Copper Losing"often occurs when CuNaX zeolites with low degree of exchange is used as catalyst in petro-chemical reactions. The structures of CuNaX zeolites with different amounts of adsorption water were determined by polycrystal X-ray diffraction.The results were refined by Rietveld method. It is discovered that migration of Cu²⁺ ion occurs as the amount of adsorption water increases, Cu²⁺ ion migrates into supercages of zeolite when it adsorbs water saturatedly but reversibly back to S（Ⅱ） position when water adsorbed decreases.The active centre of the said catalyst is Cu²⁺ ion at the S （Ⅱ） position. The mechanism of "cupper losing"is that Cu²⁺ ion has migrated into supercage where it is not constrained by oxygen atoms in the framework, then it forms intermediate substance with reactant in catalytic reaction and runs away. Therefore it can be prevented by eliminating water in the reaction system as far as possible such as by calcining the zeolite before reaction, and dehydrating the reactant etc.更多还原