Tubular SDC-Carbonate Dual-Phase Membrane Reactor for Steam Reforming of Methane With in Situ CO2 Removal

Tubular SDC-carbonate dual-phase membrane reactor for steam reforming of methane with in situ CO₂ removal

Xueliang Dong and Jerry Y.S. Lin*

School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, 85287, email: jerry.lin@asu.edu

Steam reforming of methane (SRM) is a dominant industrial process for H₂ production from fossil fuels. The reaction efficiency of SRM can be greatly improved by the in situ removal of reaction products (H₂ or CO₂) and shifting the reversible reforming beyond its conventional thermodynamic limits. The introduction of catalytic membrane reactor for in situ H₂ separation is an effective route to enhance the CH₄ conversion and has been widely studied. Additionally, the CO₂ removal has been confirmed as another promising route to promote the SRM reaction for high purity H₂ production with CO₂ capture. Typically, CO₂ sorbents are applied for in situ CO₂ removal. However, this technique suffers from the regeneration of the CO₂ sorbents. A high effective SRM process therefore requires a continuous high temperature CO₂separation technique.

In this work, for the first time, a novel catalytic membrane reactor based on a tubular ceramic-carbonate dual-phase membrane was constructed for SRM with in situ CO₂ separation. An oxygen ionic conducting electrolyte material Sm_0.2Ce_0.8O_1.9-d (SDC) was used as ceramic phase and a eutectic carbonate mixture (Li₂CO₃, Na₂CO₃ and K₂CO₃) was used as carbonate phase. A porous tubular SDC support was infiltrated with the molten carbonates to prepare a dense dual-phase CO₂ high temperature separation membrane. At 900 ^oC, the CO₂ permeation flux and permeance of this membrane are 0.9 ml·cm^-2·min^-1 and 1.5×10^-7 mol·m^-2·s^-1·Pa^-1, respectively. Commercial Ni-based catalyst was packed into the tube side of the membrane, where the SRM reaction occurred. The produced CO₂ permeated through the membrane from tube side to outer side and realized the in situ CO₂ separation. At 900 ^oC, the CH₄ conversion of 55.7% and CO₂ recovery of 39.6% were obtained. This work provides an innovative and promising hydrogen production process based on a new catalytic membrane reactor.