Patent ID: 6379645
Filing Date: 2002-04-30
Classification: C01B

Abstract:
A method for increasing the recovery of hydrogen from hydrogen/carbon oxide synthesis gas comprising the steps of:(a) subjecting said synthesis gas stream to a step selected from the group consisting of, a high temperature shift, medium temperature shift, low temperature shift, and a combination thereof to convert carbon monoxide and water vapor in said stream to carbon dioxide and hydrogen; (b) passing said synthesis gas stream after said shift or followed by heat recovery, through a pressure swing adsorption unit adapted to remove carbon oxides from said stream; said pressure swing adsorption unit operated for a cycle time beyond which carbon oxide impurities breakthrough the pressure swing adsorption unit and are contained in an effluent from said pressure swing adsorption unit; and (c) passing said effluent from step (b) through a methanator to convert residual carbon oxides in said effluent to methane to produce a purified hydrogen stream with a volumetric increase in hydrogen recovery from said pressure swing adsorption unit.