(702e) Aqueous Phase Reforming of Ethanol over Cobalt Doped Bismuth Vanadate

Cation doped bismuth vanadate (BiMeVO_x) has generated interest as a heterogeneous catalyst support due to its high oxygen conductivity. This characteristic is due to the unusual morphology of the material, in which crystalline perovskite sheets of (Bi₂O₂)²⁺ alternate with (VO₄)^2-. This anisotropy is responsible for the material’s high ionic conductivity, while limiting diffusion to a plane axis. In order to stabilize the desirable tetragonal phase, which ordinarily occurs only above 570 ⁰C, ~15% of the vanadium is replaced with a dopant (Fe³⁺, Cu²⁺, Ti⁴⁺, Co²⁺). This creates defects in the structure which increases the number of oxygen vacancies, further improving the ionic conductivity.

In this study, BiCoVOx has been investigated as a support for nickel and platinum catalysts for the aqueous phase reforming of ethanol. This process is of interest because it allows dilute fermentation broths to be directly and inexpensively converted into syngas, an important precursor for synthetic natural gas and specialty chemicals. Testing has shown BiCoVOx supported catalysts perform favorably against an alumina support. In order to best exploit the material’s unique properties, supports were prepared both by conventional combustion synthesis, yielding a highly textured, porous substrate; and by molten salt synthesis, producing micro-platelets of tunable dimensions. This highly ordered product has the highest oxygen conductivity along its axis. Thus, the best activity can be achieved by selective deposition of the catalyst on the platelet edges, which has been accomplished via strong electrostatic adsorption (SEA). To cheaply investigate this, a protocol for selective fluorescent dye uptake has been developed. By using this, a proposed SEA study can be quickly analyzed by fluorescent microscopy, to determine spatial deposition on materials that exhibit heterogeneous surface charging.