It is imperative to develop more efficient processes for conversion of biomass to liquid fuels, such that the cost of these fuels would be competitive with the cost of fuels derived from petroleum. We report a catalytic approach for the conversion of carbohydrates to specific classes of hydrocarbons for use as liquid transportation fuels, based on the integration of several flow reactors operated in a cascade mode, where the effluent from the one reactor is simply fed to the next reactor. This approach can be tuned for production of branched hydrocarbons and aromatic compounds in gasoline, or longer-chain, less highly branched hydrocarbons in diesel and jet fuels. The liquid organic effluent from the first flow reactor contains monofunctional compounds, such as alcohols, ketones, carboxylic acids, and heterocycles, that can also be used to provide reactive intermediates for fine chemicals and polymers markets.

Applying density functional theory (DFT) calculations to the rational design of catalysts for complex reaction networks has been an ongoing challenge, primarily because of the high computational cost of these calculations. Certain correlations can be used to reduce the number and complexity of DFT calculations necessary to describe trends in activity and selectivity across metal and alloy surfaces, thus extending the reach of DFT to more complex systems. In this work, the well-known family of Brønsted-Evans-Polanyi (BEP) correlations, connecting minima with maxima in the potential energy surface of elementary steps, in tandem with a scaling relation, connecting binding energies of complex adsorbates with those of simpler ones (e.g., C, O), is used to develop a potential-energy surface for ethanol decomposition on 10 transition metal surfaces. Using a simple kinetic model, the selectivity and activity on a subset of these surfaces are calculated. Experiments on supported catalysts verify that this simple model is reasonably accurate in describing reactivity trends across metals, suggesting that the combination of BEP and scaling relations may substantially reduce the cost of DFT calculations required for identifying reactivity descriptors of more complex reactions.

In this era of diminishing petroleum reserves, it is imperative that industrialized society should develop ways to utilize more effectively the abundant and renewable biomass resources available to provide new sources of energy and chemical intermediates.[1] To this end, various processes have been developed to convert biomass and biomass-derived molecules into specialty chemicals (methanol), light alkanes (C 1 -C 6 ), liquid fuels (ethanol and C 7 -C 15 alkanes), and synthesis gas.[2]As a new direction, we show herein that glycerol can be converted over platinum-based catalysts into gas mixtures of H 2 and CO (synthesis gas) at temperatures from 498 to 620 K. These temperatures are lower than those for conventional gasification of biomass (e.g. 800-1000 K).[3, 4] Synthesis gas can be used to produce fuels and chemicals; therefore, the endothermic conversion of glycerol into synthesis gas can be combined with exothermic Fischer-Tropsch and methanol syntheses to provide low-temperature and energy-efficient routes for the production of these compounds. The glycerol used can be sourced from waste glycerol streams that are currently generated as by-products from the production of biodiesel. This heat-integrated catalytic process could also be a less energy-intensive alternative to current methods of converting carbohydrates into fuel-grade ethanol.Synthesis gas production methods for conventional Fischer-Tropsch plants require either an O 2 plant or a large Fischer-Tropsch reactor to process the synthesis-gas stream diluted with N 2 from air, thereby increasing the capital costs of such facilities.[5] Furthermore, Hamelinck et al. showed that nearly 50 % of the cost of producing Fischer-Tropsch liquids from biomass is related to capital cost, [6] of which 50 % stems from biomass gasification, gas cleaning, and synthesis-gas processing. The method we present herein may allow for economic operation of a small-scale Fischer-Tropsch reactor by producing an undiluted H 2 /CO gas mixture. Indeed, our method reduces the capital cost of the Fischer-Tropsch plant by eliminating the O 2 plant or biomass gasifier and subsequent gas-cleaning steps. The conversion of glycerol into CO and H 2 takes place by Equation (1). The endothermic enthalpy change of thisreaction (350 kJ mol À1 ) corresponds to about 24 % of the heating value of the glycerol (À1480 kJ mol À1 ). The heat generated by Fischer-Tropsch conversion of the CO and H 2 to liquid alkanes such as octane (À412 kJ mol À1 ) corresponds to about 28 % of the heating value of the glycerol. Thus, combining these two reactions results in the following exothermic process, with an enthalpy change (À63 kJ mol À1 ) that is about 4 % of the heating value of the glycerol:

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First-principles, periodic, density functional theory (DFT) calculations are carried out on Pt(111) to investigate the structure and energetics of dehydrogenated ethylene glycol species and transition states for the cleavage of C-H/O-H and C-C bonds. Additionally, reaction kinetics studies are carried out for the vapor phase reforming of ethylene glycol (C 2 H 6 O 2 ) over Pt/Al 2 O 3 at various temperatures, pressures, and feed concentrations. These results are compared to data for aqueous phase reforming of ethylene glycol on this Pt catalyst, as reported in a previous publication (Shabaker, J. W.; et al. J. Catal. 2003, 215, 344). Microkinetic models were developed to describe the reaction kinetics data obtained for both the vapor-phase and aqueous-phase reforming processes. The results suggest that C-C bond scission in ethylene glycol occurs at an intermediate value of x (3 or 4) in C 2 H x O 2 . It is also found that similar values of kinetic parameters can be used to describe the vapor and aqueous phase reforming data, suggesting that the vapor phase chemistry of this reaction over platinum is similar to that in the aqueous phase over platinum.