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Co 4 N/γ-Al 2 O 3 and Co/γ-Al 2 O 3 catalysts with different metal loadings were prepared by NH 3 and H 2 -temperature programmed reaction method for the co-methanation of carbon oxides (CO and CO 2 ). The catalysts were characterized by N 2 adsorption–desorption, XRD, XPS, TEM-SAED, H 2 , CO, and CO 2 -TPD techniques. Results showed that the Co 4 N 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, 20Co 4 N/γ-Al 2 O 3 catalyst with 20 wt% metal loading showed the best performance. This catalyst achieved higher activity for CH 4 formation between 200 and 300 °C and maintained high product selectivity (⩾98%). A 250 h stability test for 20Co 4 N/γ-Al 2 O 3 was also conducted at 350 °C and increased gas hourly space velocity (GHSV; 10,000 h −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 CO 2 conversion and CH 4 selectivity were maintained even at a higher GHSV. |
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