Promoting effect of Pt, Pd and Rh noble metals to the Ni 0.03Mg 0.97O solid solution catalysts for the reforming of CH 4 with CO 2

Abstract

Reforming of CH 4 with CO 2 to produce synthesis gas was studied over Ni 0.03Mg 0.97O solid solution catalyst and its bimetallic derivative catalysts which contained small amounts of Pt, Pd and Rh, respectively (the atomic ratio of M/(Ni+Mg) was varied from 0.007 to 0.032%, M=Pt, Pd or Rh). It was found that there was a significant promotion in both activity and stability due to the addition of noble metals. The optimum loadings of these noble metals were observed at the atomic ratio of M/(Ni+Mg) ≈0.021%. Temperature programmed hydrogenation (TPH) of carbonaceous species formed during the catalytic reaction indicated that the good resistance of Ni 0.03Mg 0.97O solid solution to carbon deposition was retained on the bimetallic catalysts. Furthermore, we obtained a clear evidence showing the formation of Pt—Ni alloy particles by means of TEM and EDS observation. The kinetic study and temperature programmed reaction (TPR) of CH 4 suggest that CH 4 decomposition as the rate-determining step on the Ni 0.03Mg 0.97O is accelerated by the alloy formation. The improved stability was attributed to the promotion in catalyst reducibility.