Synthesis of high surface area nanomaterials and their application in catalysis
Aaron D. Sadow
The importance of developing high surface area nanomaterials for catalysis has been recognized for decades. The thesis show the development of ceria and carbon based nanomaterials, characterization and their potential application in catalysis.
Bio-renewable resources are considered suitable feedstocks for the production of biofuels. We have discussed the potential application of copper oxide supported on ceria for selective hydrogenation of fatty acids. Our results indicate that these catalysts are active hydrogenation catalysts at low pressure (5 bar H2) that give alcohol or alkanes as products depending on the amount of copper loaded on the ceria support. A Cu/Ce mole ratio of 0.05 in the composite catalyst showed high selective reduction of acids to alcohols. As Cu/Ce mol ratio is increased, the alkanes selectivity increased at the expense of alcohol selectivity. We think generation of enough activated H2 in the high copper loaded catalysts may lead to the subsequent reduction of alcohols into alkanes. We have shown that copper oxide and ceria act synergistically in the conversion of fatty acids into fatty alcohols. We believe metallic copper and oxygen vacancies formed under reaction conditions act as active sites for this system.
Nitrogen doped mesoporous carbons are known to be beneficial as catalysts and/ or metal supports in various catalytic applications. A key challenge of using nano-casting strategy to develop N-doped mesoporous carbons is choosing the most favorable organic precursors. The organic precursors serve as sources for both carbon and nitrogen in the resultant materials. In this context, we have discussed the development of nitrogen containing mesoporous carbons using aspartic acid as organic precursor via nano-casting strategy. Based on the textural studies by N2 physisorption, we learned the carbons exhibit high surface area and mesoporosity. Our XPS results indicate the presence of three types of nitrogen: pyridinic, pyyrrolic and quaternary in the carbons carbonized at 500 oC. Further, our FT-IR results suggest the presence of pyridinic-N in all the carbons carbonized at different temperatures. We believe the pyridinic-N, which is basic is responsible for the catalytic activity of the carbon towards the aldol condensation. The carbons were also used as supports for iron catalysts in the hydrogenation of nitrobenzene to aniline.