Autothermal hydrogen from renewable fuels in millisecond reactors

Fast and efficient renewable fuel reforming is one of the critical steps in producing H2 for fuel cells and the "hydrogen economy." The focus of this thesis is on the development of autothermal processes to produce hydrogen from renewable fuels in millisecond reactors. By enabling these self-sustaining reactions to occur in milliseconds, these processes are capable of producing large amounts of hydrogen from very small and simple equipment.; Conversion of ethanol, methanol, ethylene glycol, and glycerol directly to H2 at catalyst contact times of <10 ms was possible using catalytic partial oxidation. Millisecond reactors can be tuned by changing catalysts, flow, and feed conditions. Rh-Ce catalysts gave the highest selectivity to syngas and were the most stable. Conversion increased and syngas selectivity decreased with the addition of hydroxyl groups, but high fuel conversions (>90%) and high H2 selectivities (>80%) were achieved with all of the fuels. Adding water to the Rh-Ce catalyzed reactor increased H2 production and reduced selectivity to CO due to increased water-gas shift and steam reforming activity. The total selectivity of all unwanted products, mostly CH4 , was <3% at the H2 production maximum. Upon discovery of the optimal operating conditions, a staged heat integrated reactor was designed and built that allowed for increased hydrogen yield and heat integration. For the conditions used in these experiments, surface reactions appeared to dominate. Adsorption of all hydroxyl-containing compounds was interpreted as bonding on noble metal surfaces as an alkoxide species that completely decomposes to H2 and CO; no reaction pathways on the surface to form greater than C1 products were found to exist.; An autothermal process that made it possible to produce high yields of H2 (∼70%) from nonvolatile fuels such as soybean oil and glucose-water solutions by flash vaporization with reaction times <1 ms with a total time in the reactor <50 ms was also developed. This occurs by pyrolysis coupled with catalytic oxidation of the fuels and their fragments upon impact with a hot Rh-Ce catalyst, making it possible to catalytically transform heavy fuels directly into H2, CO, and other small molecules in milliseconds without carbon formation.