Temperature and Pressure Effects on Hydrogen Separation From Syngas

Multi-component synthetic gas (syngas) mixtures produced from the gasification of coal, low grade fuel, wastes and biomass offers a novel source of hydrogen production. Gasification also eliminates much of the pollutant emissions from the combustion these fuels. Palladium based membranes present a promising method for extracting hydrogen from syngas. Experimental results are presented from a lab scale experimental facility. This facility was designed and built to examine various types of palladium and palladium alloy membranes used to harvest hydrogen from the syngas. The thin membranes (on the order of ∼12μm) examined were supported on porous stainless-steel. This study used a mixture of pure gasses, including hydrogen, nitrogen, and carbon dioxide, to simulate syngas of different compositions. The specific focus aimed to evaluate the role of the membrane operational temperature and pressure on the hydrogen separation efficiency. Results are reported at temperatures from 325°C to 400°C and pressures from 5 to 30 psig for various concentrations of hydrogen. Results showed permeation to increase by up to 33% with a 75°C increase in temperature. Moreover, permeation increased by over 50% with an increase in partial pressure of hydrogen by only 10 psi. These results reveal that pressure has a dominant influence on enhancing membrane permeability.