Dual-enhanced steam methane reforming by membrane separation of H2 and reactive sorption of CO2

Abstract

This study proposes a dual-enhanced steam methane reforming (SMR) method for hydrogen production with simultaneous H2 membrane separation and CO2 sorption. Thermodynamic calculations and experimental studies were carried out to study the effectiveness of the dual-enhanced. Theoretically, dual-enhanced SMR was found to decrease the reaction temperature to 500°C with a CH4 conversion of 86.2% under the H2 separation ratio of 0.6 and CO2 sorption ratio of 0.95, in contrast, the CH4 conversion was 52.1% under the same conditions but without any enhancement, thus lowering energy consumption by using dual-enhanced steam reforming. A palladium membrane tube was prepared by electroless plating and used for membrane separation of H2. A fixed-bed reactor packed with complex catalyst containing nano-CaO as CO2 sorbent and NiO/Al2O3 as reforming catalyst was assembled. Experimental results indicated that with a lowered reaction temperature to 500°C, the CH4 conversion can be 62.6%. The conversion of CH4 by dual-enhanced SMR was 27.2%, higher than that obtained by conventional SMR at a reaction temperature of 600°C and a steam-to-methane (S/M) molar ratio of 4. Product gas with 98.1% H2 was directly obtained by dual-enhanced SMR.