Biological processing of carbonaceous sources using extremophiles for CO ₂-neutral ultra-pure hydrogen production

Presently, natural gas derived-synthesis gas is the main commercial source of hydrogen (H ₂) for PEM based fuel cells that effectively utilize platinum catalysts under an ambient pressure and at 80°C. Since synthesis gas invariably contains copious amounts of carbon monoxide (CO), an expensive step involving staged water-gas-shift (WGS) reactions are used to remove CO to acceptable levels (< 50 ppm) and thus prolong the Pt catalyst life. We recently reported a liquid phase, low temperature (< 150°C) approach to WGS reaction in which a single-site catalyst was used to efficiently process impure synthesis gas containing several %CO (Mahajan, U.S. patent 6,596,423 (2003)). An alternate biological approach is being developed in our laboratory that involves the use of extremophilic microorganisms such as Thermotoga neapolitana that efficiently mediates H ₂ production from glucose under ambient microaerobic atmosphere and 70°C (Van Ooteghem et al. Biotech. Lett. 26: 1223 (2004)). Itaconic acid was successfully used as a buffer to overcome pH-induced limitations of cell growth and to facilitate enhanced production of CO-free H ₂, an inherent benefit of using the biological approach. Hydrogen production, biological hydrogen, catalytic water-gas-shift, thermotoga neapolitana, low temperature catalysis.