Corrie L. Carnes

The catalytic methanol synthesis over nanoparticle metal oxide catalysts

Abstract Several nanoparticle metal oxides were prepared and studied for the catalytic production of methanol from hydrogen and carbon dioxide. These catalysts include: ZnO, CuO, NiO, and a binary system CuO/ZnO. The catalysts were prepared through sol–gel synthesis and were found, via TEM and BET, to have high surface areas and small crystallite sizes. With this in mind, the catalytic production of methanol was studied at various temperatures in a flow reactor. The percent conversion and turnover numbers were calculated for each sample, and it was found that the nanoparticle ZnO, CuO/ZnO and NiO were much more active catalysts than the commercially available materials. The nanocrystalline CuO sample was found to rapidly reduce to Cu, where it lost all activity. The results suggest that the catalytic process is efficient for several nanoparticle metal oxide formulations, however, copper metal is not active, but small copper particles in a CuO/ZnO matrix is a very active combination.

Nanocrystalline Metal Oxides as Unique Chemical Reagents/Sorbents

A new family of porous inorganic solids based on nanocrystalline metal oxides is discussed. These materials, made up of 4-7 nm MgO, CaO, Al2O3, ZnO, and others, exhibit unparalleled destructive adsorption properties for acid gases, polar organics, and even chemical/biological warfare agents. These unique sorption properties are due to nanocrystal shape, polar surfaces, and high surface areas. Free-flowing powders or consolidated pellets are effective, and pore structure can be controlled by consolidation pressures. Chemical properties can be adjusted by choice of metal oxide as well as by incorporating other oxides as monolayer films.

Unexpected Fe local order in iron oxide coated nanocrystalline magnesium oxides with exceptional reactivities against environmental toxins.

Mg oxide nanoparticles are very reactive materials used to mitigate atmospheric pollution and to sequester polluting molecules. Using Fe K-edge XAFS, we have studied the structure of iron oxide-coated MgO nanoparticles before and after reaction with CCl4. Before reaction, the local structure around Fe is totally different from that in iron oxide coatings on SrO and CaO nanoparticles, although these coated materials were prepared in the same way. In SrO and CaO, the iron oxide coating has been shown to be well separated from the bulk of the nanoparticle, whereas in MgO, Fe was found to mix with MgO. After reaction with CCl4, Fe-Cl bonds can be detected when the coated nanoparticle is saturated. Such Fe-Cl EXAFS signals have not been observed in previously studied nanoparticles.