Production of substitute natural gas

A process for producing a methane containing substitute natural gas from a primary synthesis gas containing more than 40 percent by volume of carbon monoxide on a dry basis and hydrogen comprising the steps of:

• simultaneously heating and saturating said primary synthesis gas with water;
• heating the saturated synthesis gas further and dividing the same into first and second feed gas streams;
• admixing a recycle gas stream from the product gas of second concurrent shift and methanation reactions with the first feed gas stream and subjecting the admixture to first concurrent shift and methanation reactions over a catalyst at a temperature of from 250.degree. to 550.degree. C.;
• mixing the product of the first reactions with said second feed gas stream and effecting second concurrent shift and methanation reactions on said mixture over a second catalyst at a temperature of from 250.degree. to 550.degree. C.;
• dividing the product of the second reactions into a second product gas stream and said recycle gas stream;
• and
• subjecting said second product gas stream to a carbon dioxide removal process.