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

Abstract

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 H 2 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 H 2/He, H 2/CO 2, and a ternary mixture of H 2, CO 2 and CO were separated by the composite membrane at 350, 400, and 450 °C, 14.4 bar ( P tube = 1 bar), and space velocities up to 45,000 h −1. H 2 permeation inhibition caused by reversible surface binding was observed due to the presence of both CO and CO 2 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 ( P tube = 1 bar), H 2O/CO ratios of 1.1–2.6, and GHSVs of up to 2900 h −1, considering the effect of the H 2O/CO ratio as well as temperature on the reactor performance. Experiments were also conducted with a simulated syngas feed at 14.0 bar ( P tube = 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 H 2 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 H 2 recovery were achieved at 450 °C with high throughput, made possible by the 14.4 bar reaction pressure.