Ž. The Sorption Enhanced Reaction Process SERP is a novel concept for hydrogen production by steam-methane reform-Ž . ing SMR . It uses a fixed-bed reactor packed with an admixture of a SMR catalyst and a chemisorbent for selective re-Ž . moval of carbon dioxide one of the reaction products from Ž . the reaction zone Hufton et al., 1999; Sircar et al., 2000 . The unique steps of the SERP concept allow direct production of ;90qmol. % hydrogen from the reactor at the reaction pressure. The impurities in the hydrogen product consist Ž . Ž primarily of methane -10 mol. % and trace quantities -. 50 ppm level of carbon oxides. The chemisorbent is periodically regenerated by using the principles of pressure swing Ž . adsorption PSA . The reaction can be carried out at a moderate temperature range of 450᎐550ЊC, which is much less Ž . than that of a conventional SMR reactor 800᎐900ЊC packed with reforming catalyst only. The purpose of this article is to describe the actual cyclic performance of the SERP concept for hydrogen production using a pilot-scale apparatus with a Ž . proprietary SMR catalyst noble metal on alumina and a Ž proprietary CO chemisorbent pelletized potassium carbon-2 . ate promoted hydrotalcite , which has been described earlier Ž .The SERP consists of the following cyclic steps:Step a: Sorption-Reaction. The reactants consisting of a mixture of steam and methane at pressure P and tempera-R ture T are passed through the feed end of a packed-bed R reactor containing the admixture of the catalyst and the chemisorbent. The reactor is previously pressurized at temperature T with steam to a pressure level of P . A hydro-R R gen-enriched product stream at pressure P is withdrawn R through the product end of the reactor until the carbon oxide concentration levels in the effluent gas reach a preset level. Ž .Step b: Depressurization. At the end of step a , the reactor is depressurized to near ambient pressure by withdrawing Correspondence concerning this article should be addressed to S. Sircar. desorbed and void gases through the feed end. The effluent gas is vented.Step c: E®acuation with Steam Purge. The reactor is then countercurrently evacuated to a subatmospheric pressure level of P , while introducing ambient pressure steam at D temperature T through the product end of the reactor. The R effluent gas, consisting mostly of desorbed CO and steam, is 2 vented.Step d: Pressurization. Finally, the reactor is countercurrently pressurized from P to P by introducing steam at D R temperature T through the product end while the feed end R is kept closed. The reactor is now ready to repeat a new cycle starting from step a. The reactor is externally heated in order to carry out all four steps of the process under nearly isothermal conditions. Ž . The heat is used to i supply the net endothermic heat of w reaction created by simultaneous endothermic steam Ž . Ž . methane reforming SMR , exothermic water gas shift WGS ,x Ž . and exothermic chemisorption of CO during step a of the 2 Ž . cycle and ii provide the heat...

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