A process for producing acetylene, ethylene, or both is disclosed. The process includes combusting a fuel stream to produce a combustion gas effluent stream and pyrolyzing a feed stream in a pyrolysis zone in the presence of the combustion gas effluent stream to produce a pyrolysis zone effluent stream which is further quenched and compressed. The compressed quenched stream is separated in a solvent separation column to produce a net gas stream comprising hydrogen, methane, and at least one carbon oxide and a product stream. A portion of the carbon oxide of the net gas stream is converted into methane in a methanation reactor and a reactor effluent stream is sent to an amine scrubber where carbon dioxide is removed and a methane containing stream is generated as an effluent. The methane containing stream is then recycled to the pyrolysis zone of the supersonic reactor.