Promotion effect of CO on methanation of CO2-rich gas over nanostructured modified NiO/γ-Al2O3 catalysts

Catalysts NiO/gamma-Al2O3 non-promoted and promoted with CeO2, MgO, CaO and Pt have been prepared by the impregnation method and used for hydrogenation of carbon oxides into high caloric synthetic fuel CH4. Physico-chemical properties of catalysts were determined by the methods of Brunauer-Emmett-Teller surface area analysis (BET), x-ray diffraction (XRD), hydrogen temperature programmed reduction (H-2-TPR), carbon dioxide temperature programmed desorption (CO2-TPD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The activity of catalysts was investigated for CO2 solo-hydrogenation and co-hydrogenation of CO and CO2 mixture at temperature range of 225 degrees C-400 degrees C. The particle size of all samples was found to distribute in a range of 15 degrees C-45 nm and the catalysts' surface area varied from 79 to 95 m(2) g(-1). Additives increased the thermal stability of catalyst and enhanced the dispersion and reducibility of NiO that led to improve the activity and selectivity of methanation of carbon oxides into CH4. On these catalysts, CO completely converted at 250 degrees C-275 degrees C and 80%-90% of CO2 was converted at 400 degrees C. Addition of CO in feedstock enhanced the efficacy of methanation of CO2-rich gas, increasing CO2 conversion by 3%-25% and rising CH4 selectivity up to 95%-100%.