Process intensification in hydrogen production from biomass-derived syngas

Biomass is a renewable and worldwide-abundant energy resource that shows great potential for environmentally benign power generation by minimizing greenhouse gas emissions. A "one-box" process has been proposed and studied in order to economically produce pure hydrogen from biomass-derived syngas in the presence of its common impurities through the use of the water gas shift (WGS) reaction. The heart of the process is a catalytic membrane reactor making use of carbon molecular sieve (CMS) membranes and an impurity-tolerant commercial Co/Mo/Al₂O₃ catalyst. CMS membrane stability was investigated in the presence of model tar and organic vapor compounds at experimental conditions similar to the WGS reaction environment. Experimental studies were carried out utilizing simulated biomass-derived syngas containing H₂S and NH₃ as key impurities, which was fed into the catalytic membrane reactor to produce a contaminant-free hydrogen product using the WGS reaction. The reactor performance has been investigated for various experimental conditions, and has been compared with simulation results from a mathematical model. The model was also used to study the effect of various parameters on system performance. A key observation is that both the membranes and the catalyst show satisfactory stability in the presence of impurities typically encountered in biomass-derived syngas, and that the system shows good performance, delivering higher CO conversion and hydrogen purity than when using a traditional reactor system.