CO2-recycling for CH4 production on rare-earth modified Ni-Alumina catalysts

The chemical recycling of greenhouse gas CO2 produced in hydrocarbon combustion is an attractive alternative to CO2 storage in the underground [1]. Recently have attracted particular interest the conversion of CO2 into syn-gas by the dry reforming of methane [2] and the direct conversion of CO2 into synthetic natural gas (CH4) by the methanation reaction CO2 + 4H2  CH4 + 2H2O [3]. In addition to abating the CO2 emission, the methanation has the advantage to convert hydrogen into a more easily exploitable source of energy, as is CH4. This reaction also have the advantage being thermodinamically favoured at low temperatures (H° = −165 kJ mol−1). However the methanation is helpful for greenhouse gas mitigation only if it utilizes H2 produced by non-fossil sources. Nickel containing catalysts have been reported to be very active for this reaction []. Nickel loading, support nature and the effect of promoters have been widely investigated for the removal of CO2 and CO from H2-rich streams, but only scarcely studied for CH4 production using concentrated CO2 flow. In the present work, catalysts based on nickel supported on -Al2O3, modified by rare earth oxides CeO2 and La2O3, and by MgO were prepared by wet impregnation and tested for the production of synthetic natural gas. The catalyst metal compositions were tailored in order to improve the catalytic performances at low temperature (300-400°C) and high space velocity (75000 mL h-1 g-1). Catalysts were characterized by XRD, SEM, H2-TPR, CO2-TPD, BET in order to investigate the role of promoters on nickel dispersion and surface basicity, and tested with pure reagent CO2:H2 stechiometric flow. Some tests were performed on structured catalyst, prepared washcoating active powder on cordierite monolith, with the aim of increase the gas-solid interface and the temperature stability and reduce the pressure drop along the catalyst bed.