(92a) Millisecond Conversion Of Renewable Fuels By Catalytic Autothermal Reforming

We considered the autothermal reforming of different types of biofuels at millisecond contact times to produce synthesis gas, hydrogen, and chemicals. Fuels examined include alcohols, esters, carbohydrates, biodiesel, vegetable oil, and solid biomass such as hybrid poplar. Biofuels and oxygenated compounds generally show higher conversion than fossil fuels, because the hydroxyl and ester linkages in these fuels exhibit higher sticking coefficients than saturated alkanes. Consequently, conversions of all biofuels in these processes are greater than 99%. Highly oxygenated feedstocks tend to produce mostly synthesis gas with few olefins or oxygenated products because surface reactions dominate. Larger products are formed predominantly by homogeneous reaction processes after all oxygen is consumed. Results on the production of synthesis gas by reactive flash volatilization of nonvolatile liquids and solids will also be described. We demonstrate that, by directly contacting cold liquid drops or solid particles as large as 1 mm onto a hot catalyst surface, the process can operate at steady state with no carbon formation for many hours. This occurs because, while pyrolysis of vegetable oils and carbohydrates at low temperatures produces carbon, above ~600^oC the equilibrium shifts to produce synthesis gas rather than solid carbon.