Fabio H. Ribeiro

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A hybrid hydrogen-carbon (H(2)CAR) process for the production of liquid hydrocarbon fuels is proposed wherein biomass is the carbon source and hydrogen is supplied from carbon-free energy. To implement this concept, a process has been designed to co-feed a biomass gasifier with H(2) and CO(2) recycled from the H(2)-CO to liquid conversion reactor. Modeling(More)
Catalysis by single isolated atoms of precious metals has attracted much recent interest, as it promises the ultimate in atom efficiency. Most previous reports are on reducible oxide supports. Here we show that isolated palladium atoms can be catalytically active on industrially relevant γ-alumina supports. The addition of lanthanum oxide to the alumina,(More)
The water-gas shift (WGS) reaction rate per total mole of Au under 7% CO, 8.5% CO(2), 22% H(2)O, and 37% H(2) at 1 atm for Au/Al(2)O(3) catalysts at 180 °C and Au/TiO(2) catalysts at 120 °C varies with the number average Au particle size (d) as d(-2.2±0.2) and d(-2.7±0.1), respectively. The use of nonporous and crystalline, model Al(2)O(3) and TiO(2)(More)
The kinetics of methane combustion at low temperatures are consistent with a Mars–van Krevelen redox mechanism involving the activation of methane on site pairs consisting of oxygen atoms and oxygen vacancies on the surface of PdO x crystallites. H 2 O strongly inhibits methane oxidation rates by titrating surface vacancies in a quasi-equilibrated(More)
Keywords: H2CAR process Hybrid hydrogen–carbon process Biofuels Hydrogen Biomass Transportation fuels Thermochemical Biological processes a b s t r a c t For a successful large scale implementation of biomass-to-liquid fuel for transportation, it is imperative that production of liquid fuel from biomass be maximized. For this purpose, synergistic processes(More)
The oxidation of the Pd(111) surface was studied by in situ XPS during heating and cooling in 0.4 mbar O2. The in situ XPS data were complemented by ex situ TPD results. A number of oxygen species and oxidation states of palladium were observed in situ and ex situ. At 430 K, the Pd(111) surface was covered by a 2D oxide and by a supersaturated Oads layer.(More)
The kinetics for the catalytic combustion of methane on Pd in its metal and oxide forms was measured on a foil and on large single crystals exposing initially the (111), (100), and (110) planes. The rates, reaction orders, and activation energies were not dependent on the structure of the active phase. Turnover rates were strictly proportional to the total(More)
Au/TiO(2) catalysts used in the water-gas shift (WGS) reaction at 120 °C, 7% CO, 22% H(2)O, 9% CO(2), and 37% H(2) had rates up to 0.1 moles of CO converted per mole of Au per second. However, the rate per mole of Au depends strongly on the Au particle size. The use of a nonporous, model support allowed for imaging of the active catalyst and a precise(More)
Operando X-ray absorption experiments and density functional theory (DFT) calculations are reported that elucidate the role of copper redox chemistry in the selective catalytic reduction (SCR) of NO over Cu-exchanged SSZ-13. Catalysts prepared to contain only isolated, exchanged Cu(II) ions evidence both Cu(II) and Cu(I) ions under standard SCR conditions(More)
We have estimated sun-to-fuel yields for the cases when dedicated fuel crops are grown and harvested to produce liquid fuel. The stand-alone biomass to liquid fuel processes, that use biomass as the main source of energy, are estimated to produce one-and-one-half to three times less sun-to-fuel yield than the augmented processes. In an augmented process,(More)