Process for the production of synthesis gas with conversion of CO2 into hydrogen

A process for producing liquid hydrocarbons from a feedstock that comprises at least one elementary feedstock from the group of biomass, coal, lignite, petroleum residues that boil essentially above 340° C., methane, and natural gas, said process comprising at least:

• a stage a) for gasification of said feedstock by partial oxidation in the presence of oxygen and/or steam reforming, in a gasification or zone of gasification, for the production of CO2 and a synthesis gas (SG) effluent comprising H2 and CO;
• a stage b) for separating CO2 from SG, and/or at least a portion of the effluent of the subsequent stage c);
• a stage for mixing at least a portion of the CO2 that is separated with a gas with an H2/CO ratio that is more than 3 and is derived from at least one of (A) a gaseous effluent from steam reforming of methane or natural gas, and (B) hydrogen that is produced by electrolysis of water, as well as by mixtures thereof, to obtain a first mixture that comprises CO2 and hydrogen;
• a stage c) for partial conversion with hydrogen, thermal or thermocatalytic, of the CO2 present in said first mixture according to the reaction:
• CO2+H2→CO+H2O in a specific reaction zone that is separated from said gasification zone;
• a stage d) for Fischer-Tropsch synthesis of hydrocarbons that have mostly at least 5 carbon atoms from a synthesis gas that comprises at least a portion of effluents of stage c).