Hierarchical hollow-zeolites encapsulating a gold nanoparticle for cyclohexane oxidation
摘要
We have demonstrated dual hollow zeolites encapsulating single gold nanoparticle. The dual hollow zeolites taken for research are ZSM-5 and MCM-22. The dual hollow zeolites comprise inner shell as ZSM-5, encapsulating single gold nanoparticles and outer shell comprises of MCM-22. Hierarchical hollow zeolites encapsulating gold nanoparticle facilitates shape selectivity, reduced poisoning/sintering/ agglomeration/leaching of metallic core catalyst by the dual hollow zeolite shells. Additionally, dual hollow zeolites also achieve hierarchical porosity, acidity and additional thermal stability. The oxidation of cyclohexane was selected for evaluation of current catalyst. The catalytic activity was compared with single shell hollow zeolites encapsulating gold nanoparticles for oxidation of cyclohexane to cyclohexanol and cyclohexanone. Higher conversion (65%) and selectivity (98%) towards K-A oil was achieved by dual shell of different hollow zeolites encapsulating single gold nanoparticles than single shell hollow zeolites encapsulating gold nanoparticles. Also, dual hollow zeolites encapsulating gold nanoparticles achieved higher conversion as well as higher selectivity towards K-A oil in comparison to earlier reports where higher selectivity could only be achieved at lower conversion, which made the process non-economical.
Graphical abstractSchematic diagram for synthesis of Au@ZSM-5@MCM-22