Decomposition of 2-propanol over M-OMS-2 materials and dissociation of stable molecules in plasma reactors

Date of Completion

January 2000

Keywords

Chemistry, Inorganic

Degree

Ph.D.

Abstract

The decomposition of 2-propanol over different metal cation (M: Cu 2+, Zn2+, Ni2+, Co2+, Al3+, or Mg2+) doped manganese oxide octahedral molecular sieve (M-OMS-2) materials was investigated in order to study the catalytic properties of M-OMS-2 materials. In comparison to other M-OMS-2 catalysts, Cu-OMS-2 catalyst has much higher conversion of 2-propanol and the highest selectivity to acetone at 300°C. As for the selectivity to propene, it is generally below 5%. The reaction results are discussed in consideration of characterization results of M-OMS-2 catalysts. In-situ FTIR studies suggest that Cu-OMS-2 has more active sites for 2-propanol than Al-OMS-2 and K-OMS-2. The phase transitions from cryptomelane to hausmannite, and finally to manganosite were observed with XRD studies of Cu-OMS-2 catalysts during reaction. Phase changes along with large surface area losses of M-OMS-2 materials after the reaction were observed and may account for the deactivation of the catalysts during reaction. All Cu-OMS-2 materials that either have the cryptomelane, amorphous MnOy, hausmannite, or manganosite structure show activity in the decomposition of 2-propanol to acetone. The Cu-OMS-2 materials with the hausmannite structure show the highest activity. Studies on the acidity and basicity of M-OMS-2 materials suggest that dehydrogenation of 2-propanol is not simply catalyzed by basic or acidic & basic pair sites, but probably by active sites with redox & basic properties. ^ In another research area, significant hydrogen production (0.33 mol % in products) from H2O splitting by atmospheric dielectric barrier discharges has been achieved with tubular PACT reactors at room temperature. Effects of different metal (either Ni, Pd, Rh, or Au) coated inner electrodes, type and length of outer metal (either Al or Cu) electrodes, ground state of the inner and outer electrodes, AC peak voltages applied on the reactor, and the flow rate of the feed (2.3 mol % in He) have been systematically studied. The water splitting activity varies when the type of metal coated inner electrodes, peak voltage, the length of outer electrode, and the flow rate of the feed change, but does not depend on the type of outer metal electrodes and the grounding state of the inner and outer electrodes. ^

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