Hydrogen production by aqueous-phase reforming of oxygenated hydrocarbons over supported metal catalysts

Hydrogen fuel cells have emerged as promising devices for meeting future global energy needs. In an effort towards the production of hydrogen from renewable resources, we have developed a single-step, low-temperature, aqueous-phase reforming (APR) process for the catalytic production of hydrogen from biomass-derived oxygenated hydrocarbons. In this thesis, the thermodynamic and kinetic considerations that form the basis of this process are discussed, and results of reaction kinetic studies for ethylene glycol APR over different metals are presented. These studies indicate Pt-based catalysts are effective for producing hydrogen via APR. Various reaction pathways may occur, depending on the nature of the catalyst, support, feed and process conditions. The effects of these various factors on the selectivity of the process to make hydrogen are discussed.; In an attempt to achieve high reaction rates at lower temperatures, the effect of Au on Pt catalysts for methanol reforming has been studied. It was found that although Au is known to be active for certain low-temperature reactions, such as water-gas shift, it does not show high activity for methanol reforming. Also, methanol reforming is a structure-insensitive reaction, and the addition of inactive Au to Pt does not lead to a change in the catalytic activity of Pt for methanol reforming.; To achieve fuel-cell grade hydrogen using APR, process improvements that lead to hydrogen containing low concentrations of CO are discussed. In addition, a dual-reactor strategy for processing high concentrations of glucose feeds is demonstrated. Finally, various strategies are assembled in the form of a composite process that can be used to produce fuel-cell grade hydrogen with high selectivity from concentrated feedstocks of oxygenated hydrocarbons.; The development of the APR process to make renewable, fuel-cell grade hydrogen is an important step towards establishing a hydrogen economy. Also, the selectivity issues make the process flexible, so that it can be tailored to selectively produce hydrogen or to produce an alkane stream with a desired molecular weight distribution. Accordingly, this process offers exciting research opportunities for developing new generation of heterogeneous catalysts using metals, metal alloys, supports, and promoters that are stable under aqueous-phase reaction conditions.