论文部分内容阅读
采用三种不同方法制备了Cu-Zn-Al基甲醇催化剂,然后在水相悬浮液中与H型镁碱沸石混合分散,以制得负载型甲醇催化剂.运用X射线衍射、N_2吸附-脱附、透射电镜、程序升温还原、NH_3程序升温脱附、H_2程序升温脱附和X射线光电子能谱对催化剂进行了表征.考察了催化剂催化CO加氢反应生成二甲醚和烃类的性能.该催化剂是在低和高过饱和度条件下采用共沉淀法和均匀沉淀法制得的.制备方法对前驱体的结构特性(如纯度、结晶度和催化剂颗粒粒径分布)有显著影响.低过饱和度的沉淀条件有利于Cu物种的高度分散,增加了催化剂中金属的比表面积,所得催化剂粒径分布均匀.这些效应进而会影响分子筛的性质,导致其微孔孔体积较小,分子筛酸性位被堵塞.通过Cu比表面积和CO转化速率之间的关联可考察甲醇催化剂的性能.
Cu-Zn-Al-based methanol catalyst was prepared by three different methods and then mixed and dispersed with H-type ferrierite in aqueous suspension to obtain supported methanol catalyst.Using X-ray diffraction and N 2 adsorption-desorption , Transmission electron microscopy (TEM), temperature programmed reduction, temperature-programmed desorption of NH 3, temperature-programmed desorption of H 2 and X-ray photoelectron spectroscopy were used to characterize the catalysts.The catalytic performance of the catalysts for the catalytic hydrogenation of CO to dimethyl ether and hydrocarbons was investigated. Is prepared by coprecipitation and homogeneous precipitation under low and high supersaturation conditions.The preparation method has significant effect on the structural properties of precursors such as purity, crystallinity and particle size distribution of catalyst particles.Low supersaturation Of the precipitation conditions are conducive to the high dispersion of Cu species, increasing the specific surface area of the metal in the catalyst, resulting in a uniform catalyst particle size distribution, which in turn can affect the molecular sieve properties, resulting in smaller micropores and blocked zeolite acid sites The correlation between the specific surface area of Cu and the CO conversion rate can be used to evaluate the performance of methanol catalyst.