Process to prepare a hydrogen rich gas mixture

Abstract

The invention is directed to a process to prepare a hydrogen rich gas mixture from a solid sulphur- and halogen-containing carbonaceous feedstock. The process involves the following steps. Step (a): gasification of the solid carbonaceous feedstock with an oxygen-containing gas to obtain a gas mixture comprising halogen compounds, sulphur compounds, hydrogen and at least 50 vol. % carbon monoxide, on a dry basis. Step (b): contacting the gas mixture with a quench gas or quench liquid to reduce the temperature of the gas mixture to below 900° C. Step (c) contacting the gas mixture with water having a temperature of between 150 and 250° C. to obtain a gas mixture comprising between 50 and 1000 ppm halogen and having a steam to carbon monoxide molar ratio of between 0.2:1 and 0.9:1. Step (d): subjecting the gas mixture obtained in step (c) to a water gas shift reaction wherein part or all of the carbon monoxide is converted with the steam to hydrogen and carbon dioxide in the presence of a catalyst as present in one fixed bed reactor or in a series of more than one fixed bed reactors and wherein the temperature of the gas mixture as it enters the reactor or reactors is between 190 and 230° C. Step (e): carbon dioxide and sulphur compounds are separated from the shifted gas mixture obtained in step (d) by contacting the shifted gas mixture with a solvent comprising dialkyl ethers of polyethylene glycol.