Processes for Gasification of a Carbonaceous Feedstock

A process for generating a plurality of gaseous products from a carbonaceous feedstock, and recovering a methane product stream, the process comprising the steps of:

• (a) supplying to an oxygen-blown gasifier (i) a first carbonaceous feedstock, (ii) an oxygen-rich gas stream and (iii) an aqueous stream comprising water and/or steam;
• (b) at least partially combusting the first carbonaceous feedstock with the oxygen-rich gas stream in the oxygen-blown gasifier, under suitable temperature and pressure, to generate a first gas stream comprising hydrogen, carbon monoxide and superheated steam;
• (c) introducing a second carbonaceous feedstock, a gasification catalyst and the first gas stream to a catalytic gasifier, the catalytic gasifier in communication with the oxygen-blown gasifier;
• (d) reacting the second carbonaceous feedstock and the first gas stream in the catalytic gasifier in the presence of the gasification catalyst under suitable temperature and pressure to form a second gas stream comprising a plurality of gaseous products comprising methane, carbon dioxide, hydrogen, carbon monoxide and hydrogen sulfide;
• (e) optionally reacting at least a portion of the carbon monoxide and at least a portion of the hydrogen in the second gas stream in a catalytic methanator in the presence of a sulfur-tolerant methanation catalyst to produce a methane-enriched second gas stream;
• (f) removing a substantial portion of the carbon dioxide and a substantial portion of the hydrogen sulfide from the second gas stream (or the methane-enriched second gas stream if present) to produce a third gas stream comprising a substantial portion of the methane from the second gas stream (or the methane-enriched second gas stream if present);
• (g) optionally, if the third gas stream comprises hydrogen and greater than about 100 ppm carbon monoxide, reacting carbon monoxide and hydrogen present in the third gas stream in a catalytic methanator in the presence of a methanation catalyst to produce a methane-enriched third gas stream;
• and
• (h) recovering the third gas stream (or the methane-enriched third gas stream if present),
• wherein:
• (i) at least one of step (e) and step (g) is present, and
• (ii) the third gas stream (or the methane-enriched third gas stream if present) is the methane product stream, or the third gas stream (or the methane-enriched third gas stream if present) is purified to generate the methane product stream.