Steam Reforming of Methane and Its Mixtures with Propane in a Membrane Reactor with Industrial Nickel Catalyst and Palladium-Ruthenium Foil

摘要

Steam reforming of methane and its mixtures containing 5 and 10% propane has been studied in a membrane reactor with an industrial nickel catalyst NIAP-03-01 and a membrane in the form of 30-mu m foil made of a Pd-Ru alloy. At T = 823 K and a feed space velocity of 1800 h(-1), the almost complete methane conversion is achieved, the selectivity for CO2 is more than 50%, and about 80% H-2 is recovered from the reaction mixture. High conversion of CH4 in the membrane reactor under mild conditions allows the steam reforming of its mixtures with C2+ alkanes to be conducted in a single process, as shown by the example of model mixtures containing C3H8. Under selected conditions (T = 773 or 823 K, a feed space velocity of 1800 or 3600 h(-1), a steam/methane ratio of 3 or 5, atmospheric pressure), almost complete C3H8 conversion is observed. The main "undesirable" reaction is methanation, leading to a decrease in the CH4 conversion. In the system under study, CH4 is formed with an increase in the feed space velocity. Methanation occurs as a result of C3H8 hydrocracking at a steam/feedstock ratio = 3 or the hydrogenation of CO2 as this ratio is increased to 5. The optimal conditions for steam reforming of methane mixtures containing up to 10% C3H8 are T = 823 K, steam/feedstock ratio = 5, and the feed space velocity of 1800 h(-1). Under these conditions involving evacuation of the permeate, the feedstock conversion is complete, the selectivity for CO2 is 50%, and more than 70% H-2 is recovered from the reaction mixture.