Preparation of CoOx/h-S-1 Composite and Its Catalytic Performance in Aerobic Oxidative Coupling of Thiols to Disulfides
Hierarchical Silicalite-1(h-S-1)zeolite was prepared by hydrothermal synthesis method using ethyl orthosilicate as silicon source,and tetrapropyl ammonium hydroxide as template;moreover,N-phenyl-3-amino-propyl trimethoxysilane was introduced,which played a role of supporting layer and expanding pore.Additionally,CoO,/h-S-1 composite catalyst loaded with metal oxide nanoclusters was prepared by impregnation method,and then used to catalyze the thiol oxidation coupling reaction.The characterization results of XRD,BET,XPS,SEM and TEM show that this catalyst has good MFI-typed topological structure;the cobalt species are mainly in the form of Co3O4 aggregates,and are well dispersed on the h-S-1 zeolite;there is a strong interaction between CoOx and zeolite surface through Co—O—Si bonds.CoOx/h-S-1 exhibits good catalytic activity for thiols oxidative coupling reaction.Under the optimized conditions of 50 mg 3％CoO,/h-S-1 catalysts,2 mL methanol as the reaction solvent,and reaction at 60 ℃ for 6 h,the conversion of thiols and the selectivity of disulfides can reach 91％and 100％,respectively.The catalyst has wide application range for thiol substrates.More importantly,CoO,/h-S-1 shows excellent catalytic performance in the preparation of asymmetric disulfide by cross-coupling reaction between different thiols.This paper reports a green and efficient oxidative coupling pathway of thiols,which is of great significance for the high-value utilization of sulfur resources in industry and the green preparation of sulfur-containing fine chemicals.
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