Patent ID: 8187568

Claim:
A method for producing synthesis gas from biogas, which comprises the steps of: removing carbon dioxide and hydrogen sulfide from the biogas by scrubbing, the hydrogen sulfide and the carbon dioxide are removed from the biogas in separate scrubbing stages before a catalytic conversion, the hydrogen sulfide being biologically removed by an addition of at least one of oxygen and an oxidizing agent containing oxygen and one of the oxygen and the oxidizing agent is so dosed that there is oxygen of at least 1.0% by volume in the biogas being methane; converting the biogas catalytically to the synthesis gas in a reforming process where the biogas is compressed without dehumidification, heated and mixed with superheated steam and subsequently thermal energy is additionally created during the reforming process by means of an exothermic oxidation of the oxygen contained in the biogas together with hydrogen in a catalyst bed for an endothermic conversion of the methane to the synthesis gas; and performing the reforming process as a two stage process, wherein the biogas being compressed to a pressure of 10 to 50 bar and heated to a temperature of 600 to 800° C., is subsequently mixed with oxygen and/or water and, in a first reforming step converted to at least 90% by volume of the synthesis gas at reaction temperatures of 800 to 900° C., wherein a part of required thermal energy is produced by reaction of the oxygen contained in the methane, and a further conversion up to over 99.5% by volume of the synthesis gas takes place in a subsequent second reforming stage with oxygen fed in at reaction temperatures of approximately 1,000° C.