A highly active and stable Co4N/γ-Al2O3 catalyst for CO and CO2 methanation to produce synthetic natural gas (SNG)

Abstract

Co4N/γ-Al2O3 and Co/γ-Al2O3 catalysts with different metal loadings were prepared by NH3 and H2-temperature programmed reaction method for the co-methanation of carbon oxides (CO and CO2). The catalysts were characterized by N2 adsorption–desorption, XRD, XPS, TEM-SAED, H2, CO, and CO2-TPD techniques. Results showed that the Co4N catalysts had higher activity than Co metal-supported catalysts due to their enhanced adsorption capacity, uniform metal dispersion, and superior metal-support interaction. Among the catalysts studied, 20Co4N/γ-Al2O3 catalyst with 20wt% metal loading showed the best performance. This catalyst achieved higher activity for CH4 formation between 200 and 300°C and maintained high product selectivity (⩾98%). A 250h stability test for 20Co4N/γ-Al2O3 was also conducted at 350°C and increased gas hourly space velocity (GHSV; 10,000h−1). The spent catalyst was further characterized using XRD, TEM, and TGA analysis. Results revealed that the catalyst was highly resistant to metal sintering and carbon deposition, whereas high CO and CO2 conversion and CH4 selectivity were maintained even at a higher GHSV.