(193b) Catalytic Autothermal Reforming of Carbohydrates to Synthesis Gas

Using a 3 cm packed bed of Rh-Ce/γ-Al2O3 catalyst supported on 1.3 mm diameter α-Al2O3 spheres at residence times less than 30 ms and temperatures of ~1000 °C, cellulose was autothermally converted to near equilibrium synthesis gas products in three primary zones: 1) homogeneous carbohydrate pyrolysis at the front face of the catalyst, 2) convection of pyrolysis vapors and co-feeds into the catalyst bed for oxidation, and 3) reforming of the syngas, combustion, and undesired tar products to chemical equilibrium. Rapid heat transfer from the exothermic oxidation zone powers char free pyrolysis and rapid reforming of undesired tars, producing a clean syngas product. High speed photography (1000 fps) was used to investigate carbohydrate behavior in the pyrolysis zone, elucidating the existence of an intermediate liquid phase commonly referred to as ?active cellulose.' Activity in the reforming zone was investigated using benzene as a model compound to clarify the role of syngas and combustion products in the system's approach to equilibrium. Finally, carbon negative operation was sustained by co-feeding CO2 and CH4, meaning all carbon in the fuel feed (carbohydrate and CH4) and some of the carbon in CO2 was recovered as CO.