Process for the production of substitute natural gas

A process for the production of substitute natural gas which comprises:

• a. providing from the process a supply of high pressure steam;
• b. using a portion of the high pressure steam to liquefy air and generate, from the liquefied air, gaseous oxygen;
• c. introducing the gaseous oxygen, steam and a carbonaceous material to a partial oxidation reaction zone to form an initial gas stream containing predominately hydrogen and the oxides of carbon and minor amounts of methane and carbon;
• d. passing a portion of the initial gas stream and steam through a first wet methanation reaction zone where the gas stream and steam undergo a water-gas shift reaction and methanation in contact with a low metal content wet methanation catalyst which comprises from about 5 to about 35% by weight of at least one metal from the third period of Group VIII of the Periodic Table on a temperature stabilized, ceramic alumina support, said support being heat treated at a temperature above the highest temperature encountered in said wet methanation zone prior to the addition of said metal thereto, at a temperature from about 900.degree. to about 1600.degree.F where the feed temperature to said wet methanation zone is at least about 900.degree.F and the exit temperature from said methanation zone is up to about 1600.degree.F to form methane followed by cooling of the gas stream exiting the wet methanation zone to produce high pressure process steam;
• e. passing the balance of the initial gas stream and the cooled effluent from the first wet methanation reaction zone through a plurality of wet methanation zones, each wet methanation reaction zone containing a low metal content wet methanation catalyst which comprises from about 5 to about 35% by weight of at least one metal from the third period of Group VIII of the Periodic Table on a temperature stabilized, ceramic alumina support, said support being heat treated at a temperature above the highest temperature encountered in said wet methanation zone prior to the addition of said metal thereto, at a temperature from about 900.degree. to about 1600.degree.F where the feed temperature to each wet methanation zone is at least about 900.degree.F and the exit temperature from each wet methanation zone is up to about 1600.degree.F to form additional methane followed by cooling of the gas stream exiting each wet methanation zone to produce high pressure process steam.