Dehydrogenation of ethanol over copper catalysts on rice husk ash prepared by incipient wetness impregnation

摘要

Copper catalysts supported on rice husk ash (Cu/RHA) prepared by incipient wetness impregnation and the effects of both metal loading and calcination temperature upon the surface structure structure of the catalyst precursors have been investigated. Surface characterization by XRD, TPR, SEM, and H_2-N_2O titration, and catalytic activity by ethanol dehydrogenation at temperatures between 473 and 573 K have been examined extensively. The XRD patterns and SEM images show that higher copper loading copper loading leads to the agglomeration of CuO crystallites. There is not much apparent transformation in surface morphology to be observed with the variation in calcination temperature. The TPR profiles denote the probable existence of both CuO and Cu~(2+) in the calcined copper catalysts. CuO exhibits weak metal-support interaction (MSI), while Cu~(2+) in much lower content exhibits strong MSI. Ethanol conversion and turnover frequency (TOF) show little dependence on copper loading. The activity of catalysts increases with an increase in reaction temperature. Furthermore, copper catalysts supported on rice husk ash display higher catalytic activity than those supported on silica gel, as revealed by the test of ethanol dehydrogenation.