Integration of Methane Steam Reforming and Water Gas Shift Reaction in a Pd/Au/Pd-Based Catalytic Membrane Reactor for Process Intensification

Palladium-based catalytic membrane reactors (CMRs) effectively remove H(2) to induce higher conversions in methane steam reforming (MSR) and water-gas-shift reactions (WGS). Within such a context, this work evaluates the technical performance of a novel CMR, which utilizes two catalysts in series, rather than one. In the process system under consideration, the first catalyst, confined within the shell side of the reactor, reforms methane with water yielding H(2), CO and CO(2). After reforming is completed, a second catalyst, positioned in series, reacts with CO and water through the WGS reaction yielding pure H(2)O, CO(2) and H(2). A tubular composite asymmetric Pd/Au/Pd membrane is situated throughout the reactor to continuously remove the produced H(2) and induce higher methane and CO conversions while yielding ultrapure H(2) and compressed CO(2) ready for dehydration. Experimental results involving (i) a conventional packed bed reactor packed (PBR) for MSR, (ii) a PBR with five layers of two catalysts in series and (iii) a CMR with two layers of two catalysts in series are comparatively assessed and thoroughly characterized. Furthermore, a comprehensive 2D computational fluid dynamics (CFD) model was developed to explore further the features of the proposed configuration. The reaction was studied at different process intensification-relevant conditions, such as space velocities, temperatures, pressures and initial feed gas composition. Finally, it is demonstrated that the above CMR module, which was operated for 600 h, displays quite high H(2) permeance and purity, high CH(4) conversion levels and reduced CO yields.