Patent ID: 6312658
Filing Date: 2001-11-06
Classification: B01D,B01J,C01B,Y02C,Y02E,Y02P

Abstract:
A process for producing a carbon monoxide product and a hydrogen product which comprises the steps of:(a) reacting a feedstock comprising methane and water in the presence of a steam methane reforming catalyst at a temperature ranging from 700.degree. C. to 1000.degree. C. and a pressure ranging from 2 to 50 atmospheres to form a reformate comprising hydrogen, carbon monoxide, carbon dioxide and unreacted feedstock;(b) removing water from the reformate to form a water-depleted reformate and separating the water-depleted reformate into the CO product and a CO-depleted stream;(c) separating the CO-depleted stream into the hydrogen product and a hydrogen depleted stream and compressing the hydrogen depleted stream to form a pressurized hydrogen depleted stream;(d) introducing the hydrogen-depleted stream into a plurality of reactors operated isothermally in a predetermined timed sequence and according to the following steps which are performed in a cycle within each reactor:(1) reacting the pressurized hydrogen depleted stream at a first pressure in a first reactor containing an admixture of a water adsorbent and a water gas shift catalyst under reaction conditions sufficient to convert carbon dioxide and hydrogen to carbon monoxide and to adsorb water onto the adsorbent and to form a CO-enriched stream under a relatively constant flow rate at the first pressure which is recycled into the water-depleted reformate steam of step (b);(2) countercurrently depressurizing the first reactor to a second pressure by withdrawing a mixture comprising hydrogen, carbon dioxide, carbon monoxide and water;(3) countercurrently purging the first reactor at the second pressure with a weakly adsorbing purge fluid with respect to the adsorbent wherein the weakly adsorbing purge fluid is a fluid other a CO-enriched fluid to desorb water from the adsorbent and withdrawing a mixture comprising weakly adsorbing purge fluid, unreacted feedstock, carbon monoxide and water;(4) countercurrently purging the first reactor at the second pressure with a CO-enriched purge fluid which does not comprise hydrogen and carbon dioxide to desorb the weakly adsorbing purge fluid and withdrawing a mixture comprising the weakly adsorbing purge fluid, carbon monoxide and water; and(5) countercurrently pressurizing the first reactor from the second pressure to the first pressure with the CO-enriched purge fluid prior to commencing another process cycle within the first reactor.