ZnO或K_2O助剂对Cu/SiO_2-Al_2O_3催化剂上丙三醇和苯胺气相催化合成3-甲基吲哚反应的促进作用

研究了ZnO或K2O助剂对Cu/SiO2-Al2O3上丙三醇和苯胺气相催化合成3-甲基吲哚反应的促进作用,采用X射线衍射、透射电子显微镜、H2程序升温还原、NH3程序升温脱附以及热重-差热分析等技术对催化剂进行了表征.结果表明,适量ZnO或K2O的加入可明显提高催化剂的活性、选择性和稳定性,其中以ZnO的促进作用更强.ZnO不仅能增强活性组分Cu与SiO2-Al2O3载体之间的相互作用、提高Cu在载体表面的分散度,而且可有效抑制反应过程中Cu粒子的烧结;而K2O的加入却降低了Cu分散度,但也对反应过程中Cu粒子的烧结有所抑制.ZnO或K2O的加入均不同程度地增加了Cu/SiO2-Al2O3催化剂的弱酸中心数量,从而促进3-甲基吲哚的生成.

Promoting Effect of ZnO or K2O on Cu/SiO2-Al2O3 Catalyst for Vapor-Phase Synthesis of 3-Methylindole from Glycerol and Aniline

The promoting effect of ZnO or K2O promoter on Cu/SiO2-Al2O3 catalyst for the vapor-phase synthesis of 3-methylindole from glycerol and aniline was studied.The catalyst samples were characterized by X-ray diffraction,transmission electron microscopy,H2 temperature-programmed reduction,NH3 temperature-programmed desorption,and thermogravimetric and differential thermal analysis.The results indicated that the addition of an appropriate amount ZnO or K2O to Cu/SiO2-Al2O3 increased the activity and selectivity as well as the stability of the catalyst remarkably,and ZnO exhibited better efficiency than K2O.ZnO not only reinforced the interaction between the active component and the support,promoted the dispersion of copper particles on the support,but also inhibited the sintering of copper particles during the reaction.K2O could suppress the sintering of copper particles during the reaction to some extent although it did not improve the dispersion of copper particles on the support.The addition of ZnO or K2O to Cu/SiO2-Al2O3 increased the number of weak acid sites in different degrees,which promoted the synthesis of 3-methylindole.