| In this thesis we develop promising new aqueous-phase catalytic processes for the conversion of biomass into Hydrogen and alkanes. Hydrogen can be produced by aqueous-phase reforming (APR) of biomass derived oxygenated hydrocarbons at low temperatures (423--538 K) in a single reactor over supported metal catalysts. The desired pathway for the production of H 2 from oxygenated hydrocarbons involves cleavage of C-C bonds as well as C-H and/or O-H bonds to form adsorbed CO on the catalyst surface, followed by removal of the adsorbed CO by the water-gas shift reaction. Undesired pathways occur by cleavage of C-O bonds and hydrogenation of CO and CO2 to form alkanes.; Liquid alkanes ranging from C1 to C6 can be produced through a bi-functional pathway in which sorbitol (hydrogenated glucose) is repeatedly dehydrated by a solid acid (SiO2-Al2O 3) or a mineral acid (HCI) catalyst and then hydrogenated on a metal catalyst (Pt or Pd). Hydrogen, which is needed for the hydrogenation reaction, can be produced in-situ by aqueous-phase reforming of sorbitol over a metal catalyst (such as Pt) that facilitates C-C bond cleavage and water-gas shift reactions, or it can be co-fed to the reactor with the aqueous sorbitol reactant.; Liquid alkanes ranging from n-C7 to C15 can be selectively produced from carbohydrates by combining the dehydration/hydrogenation process with a C-C bond forming aldol condensation step over solid base catalysts to form large organic compounds. The reaction mixtures were then hydrogenated, using a Pd catalyst, to increase the aqueous solubility of these molecules and to minimize possible coking reactions that may take place from unsaturated molecules in the following step. The organic molecules were then converted into alkanes by dehydration/hydrogenation over bi-functional catalysts containing acid and metal sites in a 4-phase reactor in which the aqueous organic reactant becomes more hydrophobic, and a hexadecane alkane stream removes hydrophobic species from the catalyst before they go on further to form coke. These liquid alkanes are of the appropriate molecular weight to be used as transportation fuel components, and they contain 90% of the energy of the carbohydrate and H2 feeds. |
