High pressure palladium membrane reactor for the high temperature water–gas shift reaction

The water–gas shift (WGS) catalytic membrane reactor (CMR) incorporating a composite Pd-membrane and operating at elevated temperatures and pressures can greatly contribute to the efficiency enhancement of several methods of H2 production and green power generation. To this end, mixed gas permeation experiments and WGS CMR experiments have been conducted with a porous Inconel supported, electroless plated Pd-membrane to better understand the functioning and capabilities of those processes. Binary mixtures of H2/He, H2/CO2, and a ternary mixture of H2, CO2 and CO were separated by the composite membrane at 350, 400, and 450 °C, 14.4 bar (Ptube = 1 bar), and space velocities up to 45,000 h−1. H2 permeation inhibition caused by reversible surface binding was observed due to the presence of both CO and CO2 in the mixtures and membrane inhibition coefficients were estimated. Furthermore, WGS CMR experiments were conducted with a CO and steam feed at 14.4 bar (Ptube = 1 bar), H2O/CO ratios of 1.1–2.6, and GHSVs of up to 2900 h−1, considering the effect of the H2O/CO ratio as well as temperature on the reactor performance. Experiments were also conducted with a simulated syngas feed at 14.0 bar (Ptube  = 1 bar), and 400–450 °C, assessing the effect of the space velocity on the reactor performance. A maximum CO conversion of 98.2% was achieved with a H2 recovery of 81.2% at 450 °C. An optimal operating temperature for high CO conversion was identified at approximately 450 °C, and high CO conversion and H2 recovery were achieved at 450 °C with high throughput, made possible by the 14.4 bar reaction pressure.