Continuous production of H₂ at low temperature from methane decomposition over Ni-containing catalyst followed by gasification by steam of the carbon on the catalyst in two parallel reactors operated in cyclic manner

Abstract

CO-free H₂ in close to stoichiometric amounts was produced continuously at a constant H₂ production rate by the stepwise steam reforming of methane at low temperature (500°C) in two parallel catalytic reactors operated in cyclic manner. The process involved two simultaneous reactions: first, catalytic decomposition of methane to H₂ and carbon (deposited on the catalyst), and second, gasification of the carbon deposited on the catalyst by steam to H₂ and CO₂. The two reactions were carried out separately in two parallel reactors (both containing the same Ni-containing catalyst), operated in cyclic manner by switching a methane-containing feed and a steam-containing feed between the two reactors at a predecided interval of time. The process shows best performance at an optimum value of the feed switchover time. Among the different Ni-containing metal oxide (ZrO₂, MgO, ThO₂, CeO₂, UO₃, B₂O₃ or MoO₃) and zeolite [HZSM-5, Hβ, HM, NaY, Ce(72)NaY, or Si-MCM-41] catalysts, the Ni/ZrO₂ and Ni/Ce(72)NaY showed promising results for the cyclic process.