HYDROPYROLYSIS PROCESS FOR PREPARING METHANE

摘要

An improved process for producing a methane-enriched gas wherein a hydrogen-deficient carbonaceous material is treated with a hydrogen-containing pyrolysis gas at an elevated temperature and pressure to produce a product gas mixture including methane, carbon monoxide and hydrogen. The improvement comprises passing the product gas mixture sequentially through a water-gas shift reaction zone and a gas separation zone to provide separate gas streams of methane and of a recycle gas comprising hydrogen, carbon monoxide and methane for recycle to the process. A controlled amount of steam also is provided which when combined with the recycle gas provides a pyrolysis gas for treatment of additional hydrogen-deficient carbonaceous material. The amount of steam used and the conditions within the water-gas shift reaction zone and gas separation zone area controlled to obtain a steady-state composition of pyrolysis gas which will comprise hydrogen as the principal constituent and a minor amount of carbon monoxide, steam and methane so that no external source of hydrogen is needed to supply the hydrogen requirements of the process. In accordance with a particularly preferred embodiment, conditions are controlled such that there also is produced a significant quantity of benzene as a valuable coproduct.