Experimental investigation on methanation reaction based on coal gasification in supercritical water

Supercritical water gasification is a promising technology because it can convert coal into H₂ and CO₂ which has potential for CH₄ production. In order to obtain the optimal operating parameter for methane production, experimental investigations were conducted in the typical operating parameters: reaction temperature 380–520 °C, reaction residence time 6–10 min with different type of Raney-Ni. Gas mixture with volume ratio of 4:1 of H₂ and CO₂ as a typical production of coal gasification in supercritical water was used as feedstock. The experiments results showed that Raney-Ni 4110 has the best performance in the methanation reaction and 400 °C reaction temperature and long residence time favored CH₄ production. Based on the obtained optimal operation parameter, one-step CH₄ production by Hongliulin gasification in one reactor with certain residence time at 400 °C was conducted. The results showed that one-step coal gasification was an efficient way to produce a high yield of CH₄, and carbon gasification efficiency above 99% was achieved.