In Situ Transformation of ZIF-8 into Porous Overlayer on Ru/ZnO for Enhanced Hydrogenation Catalysis

Abstract

Supported metal catalysts play a significant role in heterogeneous catalysis in liquid phase reaction systems, but they usually suffer from a stability problem. Encapsulation of active metal species without the compromise of catalytic performance has been considered as an effective strategy. Here, we report an ultrastable Ru-based catalyst with particle size of around 1.1 nm for selective hydrogenation reaction. The highly dispersed Ru species are covered by the in situ formed porous N–C–ZnO overlayer, which is induced through the transforming of ZIF-8 shell that derives from a ZnO substrate. The resulting Ru/ZnO@N–C–ZnO catalyst can exhibit good stability in the hydrogenation of p-chloronitrobenzene after 20 cyclic runs with 100% selectivity toward p-chloroaniline. Comparatively, the naked Ru/ZnO catalyst with larger Ru particles shows serious metal leaching issue with inferior stability and poor selectivity. It is revealed that the excellent performance of Ru/ZnO@N–C–ZnO is attributed to the porous overlayer, which strengthens the bonding of Ru nanoparticles on ZnO.