CO2 hydrogenation into CH4 on NiHNaUSY zeolites

CO2 hydrogenation into methane was carried out over catalysts containing nickel and cerium species supported on a HNaUSY zeolite, using an H-2/CO2 ratio of 4 and temperatures ranging from 250 to 450 degrees C. Interesting CO2 conversions and CH4 selectivities were achieved for Ni-zeolite catalysts prepared by impregnation. Conversion increased with the Ni content from 2 to 14%, due to the higher amount of Ni species after reduction. A further enhancement of the catalysts performances was noticed when doping the Ni-zeolites catalysts with 3-15% of Ce. Actually, the presence of CeO2 after reduction might promote CO2 activation into CO, the final catalyst properties being due to the synergetic effect between the metal active sites and the promoter. Furthermore, almost no deactivation due to sintering was observed after 10 h of reaction at 400 degrees C. Comparing these results with those reported in literature it is possible to conclude that zeolites have great potential to be used as catalyst supports for the CO2 methanation reaction. In fact, taking the commercially available and widely used HNaUSY zeolite, it was possible to reach conversions and selectivities similar to those previously found in the literature for the best CO2 methanation catalysts that use potentially more expensive bulk cerium oxide supports, even without performing any optimization of the zeolite support. (C) 2013 Elsevier B.V. All rights reserved.