Naftali Opembe

Green decomposition of organic dyes using octahedral molecular sieve manganese oxide catalysts.

The catalytic degradation of organic dye (methylene blue, MB) has been studied using green oxidation methods (tertiary-butyl hydrogen peroxide, TBHP, as the oxidant with several doped mixed-valent and regular manganese oxide catalysts in water) at room and higher temperatures. These catalysts belong to a class of porous manganese oxides known as octahedral molecular sieves (OMS). The most active catalysts were those of Mo(6+)- and V(5+)-doped OMS. Rates of reaction were found to be first-order with respect to the dye. TBHP has been found to enhance the MB decomposition, whereas H(2)O(2) does not. Reactions were studied at pH 3-11. The optimum pH for these reactions was pH 3. Dye-decomposing activity was proportional to the amount of catalyst used, and a significant increase in catalytic activity was observed with increasing temperature. X-ray diffraction (XRD), energy dispersive spectroscopy (EDX), and thermogravimetric analysis (TGA) studies showed that no changes in the catalyst structure occurred after the dye-degradation reaction. The products as analyzed by electrospray ionization mass spectrometry (ESI-MS) showed that MB was successively decomposed through different intermediate species.

Light-Assisted Synthesis of Metal Oxide Heirarchical Structures and Their Catalytic Applications

Short reaction times and morphology control in the synthesis of inorganic materials under nonthermal conditions remain a challenge. Herein we report a rapid, self-templating, and nonthermal method based on ultraviolet light to prepare metal oxide hierarchical structures. With this method, the morphology of the metal oxides was controlled readily without using templates.

Studies on Dehydrogenation of Ethane in the Presence of CO2 over Octahedral Molecular Sieve (OMS‐2) Catalysts

Carbon dioxide, a major greenhouse gas, can be used as a source of carbon. Conversion of CO2 into organic compounds has been studied intensively. For example, ethane catalytic dehydrogenation [Equation (1)] offers an attractive route for converting CO2. Firstly, the coke-formation problem, particularly troublesome in the steam-cracking industry, can be solved by treating the coke with CO2 to generate CO over the catalyst. In addition, CO2 can act as a medium for supplying heat to the endothermic dehydrogenation reaction. 4] Furthermore, the products from Equation (1), C2H4 and CO, are precursors for olefin/CO copolymerization reactions. By varying the feedstock ratio (C2H6/CO2) in the reaction, different ratios of the products (C2H4/CO) can easily be obtained for the specific copolymerization process. Hence, the dehydrogenation of ethane in the presence of CO2 is an ideal feedstock for any process involving ethylene carbonylation with an additional benefit of recycling the greenhouse gas.