Water gas shift reaction process

A process for increasing the hydrogen content of a synthesis gas derived from the gasification of coal, petroleum coke or biomass, said synthesis gas comprising hydrogen and carbon oxides and having a carbon monoxide content ≧45 mole % on a dry-gas basis, comprising the steps of:

• (i) combining the synthesis gas with steam to form a steam-enriched feed gas mixture
• (ii) passing the feed gas mixture at an inlet temperature in the range 220-370° C. over a water-gas shift catalyst to form a hydrogen-enriched shifted gas mixture having a carbon monoxide content ≦10 mole % on a dry gas basis, and
• (iii) recovering the hydrogen-enriched shifted gas mixture,
• wherein 20 to 80% by volume, a portion of the hydrogen-enriched shifted gas mixture is recycled to the feed gas mixture.