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

Resumo

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-μm 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% H₂ 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% H₂ is recovered from the reaction mixture.