Advanced Reforming System for Hydrogen Station using CO₂ elective Membrane

Abstract

In this study, we developed a novel membrane reactor consisted of CO shift catalysts and a membrane for CO₂ separation. First, we developed facilitated transport membranes for CO₂ separation. We tested several carriers to achieve high CO₂ permeance (1x10^-4mol/m²skPa) and high CO₂/H₂ selectivity (100). We successfully achieved the target values even at the elevated temperature (160°C). In addition, the developed membrane had good stability. It was confirmed that high performance was maintained stably for 400 hours at 160°C. Secondly, we developed CO shift catalysts, which have high activity for the CO shift reaction at low temperature region. As a result, we succeeded in the development of both precious metal-based catalysts, and Cu-based catalysts. Thirdly, a membrane reactor could be fabricated by combining the developed CO₂ selective membranes and CO shift catalysts. Observed CO and CO₂ concentrations at the feed-side exit of the membrane reactor were lower than 10 ppm and 1%, respectively. Using membrane reactor it is possible to reduce both CO and CO₂ to lower than equilibrium level. Finally, we performed trial design of the total system of a hydrogen station equipped with the developed membrane reactor and evaluated the effect of the membrane reactor on downsizing of the total system and improvement of efficiency.