Catalytic partial oxidation of methane to syngas over Ca-decorated-Al2O3-supported Ni and NiB catalysts

One wt% Ni and 1 wt% NiB catalysts supported on Ca-decorated gamma-Al2O3 (Ca-AlO) Supports were prepared by conventional impregnation and chemical reduction methods. These supported catalysts were applied for the catalytic partial oxidation of methane (POM) to syngas. The two low-Ni-loading catalysts have shown high activity/selectivity for the POM, as good as those of I wt% Rh and 10 wt% Ni catalysts supported on commercial gamma-Al2O3 support (AlO). But their coking resistivity was remarkably better than that of 10 wt% Ni/AlO. The coke formation over these catalysts decreased in the following order: 10 wt% Ni/AlO >> 1 wt% Ni/Ca-AlO > 1 wt% NiB/Ca-AlO similar to 1 wt% Rh/ AlO. The key factor in the improvement of the carbon resistance was to decrease the metallic Ni particle size through the lowering of Ni loading combined with the addition of B promoter. The low Ni loading has been achieved by covering the support with a CaAl2O4 layer, and decreasing the catalyst calcination temperature to similar to 723 K. The formation of crystalline carbon was greatly Suppressed on the NiB catalysts due to the highly dispersed nature; such formation significantly improved the thermal stability of the Ni particles. (c) 2005 Elsevier B.V. All rights reserved.