Synthetic natural gas production by sorption enhanced steam hydrogasification based processes for improving CH4 yield and mitigating CO2 emissions

•The increase of H2/C ratio favored more H2 and CH4 productions.•The increase of Steam/C ratio led to higher yields of H2, CO, and CO2.•SE-SHR-Methanation process maximized CH4 production with nearly zero CO2 emissions.•The optimum gasification conditions for SNG were H2/C of 1.08 and Steam/C of 2.22.•SE-SHR-Methanation process has higher carbon conversion efficiency to CH4 of 39.8%.