Temperature and Pressure Effects on Hydrogen Separation From Syngas

Multicomponent 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 offer a promising method for extracting hydrogen from syngas. Experimental results are presented from a laboratory scale experimental facility. This facility was designed and built to examine various types of palladium and palladium alloy membranes for harvesting hydrogen from the syngas. The thin membranes (on the order of ∼12 μm) examined were supported on porous stainless-steel. A mixture of pure gasses consisting of hydrogen, nitrogen, and carbon dioxide were used to simulate syngas of different composition. The specific focus was on evaluating the role of operational temperature and pressure of membrane on the separation efficiency of hydrogen. Results are reported at temperatures from 325 °C to 400 °C and pressures from 5 to 30 psi (gauge) for various concentrations of hydrogen in the gas mixture. Results showed permeation to increase by up to 33% with a 75 °C increase in temperature. Permeation increased by over 50% with an increase in partial pressure of hydrogen by only 10 psi. These results provide clean hydrogen recovery from syngas obtained from gasification and pyrolysis of wastes and biomass.