Methane steam reforming using a membrane reactor equipped with a Pd-based composite membrane for effective hydrogen production

Abstract

Herein, a methane steam reforming (MSR) reaction was carried out using a Pd composite membrane reactor packed with a commercial Ru/Al2O3 catalyst under mild operating conditions, to produce hydrogen with CO2 capture. The Pd composite membrane was fabricated on a tubular stainless steel support by the electroless plating (ELP) method. The membrane exhibited a hydrogen permeance of 2.26 x 10(-3) mol m(2) s(-1) Pa (-0.5), H-2/N-2 selectivity of 145 at 773 K, and pressure difference of 20.3 kPa. The MSR reaction, which was carried out at steam to carbon ratio (S/C) = 3.0, gas hourly space velocity (GHSV) = 1700 h(-1), and 773 K, showed that methane conversion increased with the pressure difference and reached 79.5% at Delta P = 506 kPa. This value was similar to 1.9 time higher than the equilibrium value at 773 K and 101 kPa. Comparing with the previous studies which introduced sweeping gas for low hydrogen partial pressure in the permeate stream, very high pressure difference (2500-2900 kPa) for increase of hydrogen recovery and very low GHSV (<150) for increase hydraulic retention time (HRT), our result was worthy of notice. The gas composition monitored during the long-term stability test showed that the permeate side was composed of 97.8 vol% H-2, and the retentate side contained 67.8 vol% CO2 with 22.2 vol% CH4. When energy was recovered by CH4 combustion in the retentate streams, pre-combustion carbon capture was accomplished using the Pd-based composite membrane reactor.