Hydrogen production using Ni-Rh on ZrO2 as potential low-temperature catalysts for membrane reactors

The CO2 reforming of CH4 over Ni-Rh mono- and bimetallic catalysts supported on ZrO2 was investigated. The catalysts were prepared by wet impregnation with 0.2 wt% Rh and 2 wt% Ni. The solids were calcined at 823 K in air flow and were reduced at 973 K in flowing hydrogen before being tested in a fixed-bed reactor. The results showed that the bimetallic solid had the highest activity at 823 K but monometallic Rh was the only stable catalyst. The catalysts were characterized through XRD, XPS, and TPR. TGA, DSC, TPH, SEM, and Raman spectroscopy were used in order to characterize the carbonaceous deposits. Carbon deposits with different reactivity were detected. A low-carbon deposition was observed on Rh (0.2%)/ZrO2 which exhibited a stable activity after 100 h on stream. The results suggest a significant metal-support interaction and a strong metal-metal interaction in the bimetallic solid. (C) 2002 Elsevier Science (USA).