James F. Roth

Copper oxide supported on alumina: III. X-ray K-absorption edge studies of the Cu2+ species

Abstract X-Ray K-absorption edge spectroscopy studies were performed on samples containing cupric ion supported on γ-alumina. It was found that, at lower concentrations of cupric ion, a surface phase is present that resembles the structure of copper aluminate. Parameters that affect the formation of this aluminate phase include the surface area of the alumina and the concentration of cupric ions. The aluminate phase is undetectable by X-ray diffraction. It is proposed that the aluminate surface phase accounts for the sharp rise in magnetic susceptibility that has been previously noted in the susceptibility isotherm of the system copper oxide-on-alumina. When samples containing the aluminate surface phase are reduced and reoxidized in the absence of moisture, the aluminate is converted to cupric oxide. Three distinguishable phases have now been identified in composites containing cupric ions dispersed on alumina: isolated cupric ions, a copper aluminate surface phase, and cupric oxide. The chemical bonds in the first two phases are apparently the same, and different from those in the third one.

Kinetics of the catalytic vapor phase carbonylation of methanol to acetic acid

Abstract The reaction kinetics have been established for the low pressure vapor phase catalytic carbonylation of methanol to acetic acid using a solid supported rhodium complex catalyst. The catalyst is a heterogeneous analog of a previously developed homogeneous liquid phase catalyst system based upon a rhodium complex and an iodide promoter. Significantly, the reaction order dependencies are identical to those established for the liquid phase reaction (i.e., first order in iodide and independent of methanol and carbon monoxide concentrations). This suggests that in spite of the obvious physical differences between these heterogeneous and homogeneous catalysts, a similar chemical reaction mechanism is probably operative.

Supported metal complex catalysts

Abstract Metal complexes supported on porous solids have been found to be active catalysts for hydrocarbon conversion reactions, both in the presence and absence of a solubilizing liquid phase. Four of the metal complexes were more active when dissolved in a liquid phase: an isomerization catalyst, RhCl3; three hydroformylation catalysts, (Pφ3)2RhCOCl, (Asφ3)2RhCOCl and Co2(CO)6 (PBu3)2. For the hydrogenation catalyst (Pφ3)3 RhCl, however, the supported solid catalyst was appreciably more active than its supported liquid-phase counterpart. An active supported liquid-phase catalyst can be made from almost any type of non-volatile catalyst solution, provided that the reactants and products are gases at reaction conditions.

Catalytic vapor phase hydroformylation of propylene over supported rhodium complexes

Abstract Recently, it has been shown that transition metal compounds such as phosphine and arsine complexes of rhodium promote hydroformylation catalysis homogenously in the liquid phase. In the present investigation, these organometallic complexes were impregnated on carbon and alumina supports and employed as solid phase catalysts for the heterogeneous vapor phase hydroformylation of propylene to butyraldehyde. Both the supported phosphine and arsine complexes exhibited good activity (30% conversion of propylene to butyraldehyde), with the phosphine complex also displaying good long-term stability as a heterogeneous catalyst. These results demonstrate that organometallic complexes can be employed as catalysts either homogeneously or heterogeneously and may, in either case, exhibit similar catalytic properties.