Sorption-enhanced reaction process for hydrogen production

A novel concept called Sorption Enhanced Reaction Process (SERP) for hydrogen production by steam-methane reformation (SMR) reaction uses a fixed packed column of an admixture of an SMR catalyst and a chemisorbent to remove carbon dioxide selectively from the reaction zone. The chemisorbent is periodically regenerated by using the principles of pressure swing adsorption. The SERP process steps allow direct production of igh-purity hydrogen (>95 mol %) at high methane to hydrogen conversion (>80%) with dilute methane (<5 mol %) and trace carbon oxide (similar to 50 ppm) impurities at the reaction pressure by operating the reactor at a low temperature of 450 degrees C. A conventional plug-flow reactor packed with catalyst alone not only needs to be operated at a much higher temperature (>650 degrees C) to achieve the same methane to hydrogen conversion, but produces a much lower purity of hydrogen product (similar to 75 mol %) with a large quantity of carbon oxide (similar to 20 mol %) impurities. A novel chemisorbent, which reversibly sorbs carbon dioxide in the presence of excess steam at a temperature of 300-500 degrees C, was developed for application in the SERP and the process is experimentally demonstrated in a bench-scale apparatus.