Methane Nonoxidative Aromatization over Ru−Mo/HZSM-5 at Temperatures up to 973 K in a Palladium−Silver/Stainless Steel Membrane Reactor

Pd-based composite membranes supported on porous stainless steel offer high permeability and good mechanical stability. They represent an appropriate alternative in catalytic membrane reactors. In this study, Pd−Ag/porous stainless steel membranes prepared by electroless plating were used in the oxygen-free methane aromatization over Ru−Mo/HZSM-5 in a catalytic membrane reactor at temperatures up to 973 K. The 0.5% Ru−3% Mo/HZSM-5 catalyst, prepared by incipient-wetness co-impregnation, was highly selective toward benzene production. Despite attained methane conversions well beyond the thermodynamic conversion, the continuous withdrawal of coproduced H 2 promoted the formation and deposition of low-H/C carbonaceous species especially at high temperatures. At a methane space velocity of 270 mL(STP)·h -1 ·g -1 and a temperature of 873 K, a maximum conversion of methane to benzene equal to ca. 8% was obtained. When the temperature was raised to 973 K, the maximum conversion culminated at ca. 17% but was accompanied with time by a faster falloff in methane conversion compared to that observed at 873 K.