Title

Selective catalytic reactions using transition metal oxides

Date of Completion

January 2000

Keywords

Chemistry, Inorganic

Degree

Ph.D.

Abstract

Due to increasing regulations regarding the use of chlorine in bleaching agents, there is a need to find alternative bleaching agents that are environmentally safe and cost-effective. H2O2 is a good candidate based on its oxidizing strength, cost-effectiveness, and its by-products like H 2O and O2. However, under mild conditions such as those used in laundry bleaching (pH 7–10, 25°C, H2O2 has low bleaching activity. In order to activate H2O2, metals and metal oxide catalysts are often added. In this work, the evaluation of transition metal oxide powders, sols, and gels were carried out to activate H2O2. Ultraviolet/Visible (UV/Vis) spectroscopic studies were used to follow the decomposition of pinacyanol chloride (PC) dye in the presence of H2O2 and catalysts in aqueous solution. ^ One material that showed promise in dye decomposition studies was a complex of Mn2+ and picolinic acid (PicA). PicA is a bidentate ligand which can coordinate to Mn via its N and O atoms. Such materials are modeled after a biomimetic approach since Mn plays an important role in photosynthetic H2O oxidation. The manganese(II) picolinate catalysts were prepared as precipitates and encapsulated inside NaY zeolites. The materials were characterized and tested in the catalytic oxidation of cyclohexane using tert-butyl hydroperoxide (TBHP) as an oxidant, and found to be highly active catalysts. ^ The U.S. Army is interested in destroying the nearly 25,000 tons of chemical warfare agents that are stockpiled at various sites in the United States. Dimethyl methylphosphonate (DMMP) is a chemical warfare simulant, which is much less toxic than chemical warfare agents, and therefore, can be studied in the lab safely. In this work, gas phase decomposition reactions of DMMP were examined over amorphous manganese oxide (AMO) catalysts. The goals of this work are to oxidatively decompose DMMP into benign products, such as CO2 using both photo- and thermal catalytic methods. In addition, DMMP decomposition reactions were studied over manganese oxide catalysts supported on Al2O3. ^