一种环己醇催化脱氢制环己酮用高效新型催化剂

Abstract

用SC2O3作为促进剂,研发出一种高效新型SC2O3促进的Cu-znO-Al2O3基催化剂(记为CuIznJAlk-XSCX),考察其对环己醇脱氢制环己酮的催化性能.实验结果显示,在组成经优化的Cu6zn3Al0.7SC0.3催化剂上,常压,523 k,n(C6H11OH)∶n(n2)=1∶19和空速(gHSV)=43 200Ml/(H·g)的反应条件下,环己醇脱氢的转化率达53.7%,产物环己酮的时空产率为5 344Mg/(H·g),这2个值均为不含SC2O3的基质催化剂Cu6zn3Al1的相应值(42.4%,4 222Mg/(H·g))的1.27倍.催化剂的表征结果显示,SC2O3的修饰调变作用可能是由于SC2O3在znO晶格中高的溶解度.少量SC2O3在znO晶格中的溶解在znO表面产生阳离子空位形式的SCHOTTky缺陷,通过这些表面阳离子空位接纳Cu+离子使Cuy0-Cu+原子簇得以稳定化.这有助于抑制催化活性Cuy0纳米颗粒的团聚烧结,保持Cu组分的高分散度,于是显著地提高催化剂的活性和操作稳定性.该催化剂具有应用前景.

A type of Sc2O3-promoted Cu-ZnO-Al2O3 catalyst was developed.The catalyst displays excellent performance for dehydrogenation of cyclohexanol to cyclohexanone.Over a Cu6Zn3Al0.7Sc0.3catalyst under the reaction condition of atmospheric pressure,523 K,n(C6H11OH)∶n(N2)=1∶19and GHSV=43 200 mL/(h·g),the conversion of cyclohexanol dehydrogenation reached53.7%,with the STY of cyclohexanone being 5 344mg/(h·g);both values were 1.27 times of those obtained with the Cu-ZnOAl2O3 catalyst not containing Sc2O3,42.4% and 4 222 mg/(h·g).Characterization of the catalyst revealed that the pronounced modification action of Sc3+may be due to the high solubility of Sc2O3 in the ZnO lattice.Solution of a small amount of Sc2O3 in the ZnO lattice resulted in the formation of Schottky defects in the form of cationic vacancies at the surface of ZnO,where the Cuy0-Cu+clusters can be better stabilized through the Cu+accommodated at the surface vacant cation-sites.This would be conducive to inhibiting the aggregation and sintering of the catalytically active Cuy0nano-particles and preserving high dispersion degree of Cu composition,so that the activity and operating stability of the catalyst were markedly improved.