DFT, microcalorimetric, and infrared spectroscopic studies of oxygenated hydrocarbon reactions on platinum based catalysts

The need for alternative feedstock and fuel sources has sparked oxygenated hydrocarbon research. These oxygenates possess several advantages compared to hydrocarbons including: (1) more environmentally benign, (2) high reactivity, (3) renewable, (4) domestic production, and (5) these compounds are often waste products in other chemical processes. Oxygenates are highly reactive on noble metals such as Pt and Sn alloying alters catalyst selectivity. The main scope of this work is applications of molecular modeling to aid in the analysis of experimental kinetic, microcalorimetric and infrared spectroscopic investigations for oxygenates on Pt and Pt-Sn catalysts. The molecular modeling was conducted using density functional theory (DFT) on metal slabs.; Kinetic models for reactions of oxygenated hydrocarbons over Pt catalysts are proposed based on studies. In addition, DFT calculations are also used in model development. The proposed models capture the essential surface chemistry involved in the conversions of these oxygenated hydrocarbons on Pt based catalysts. The results from DFT calculations show that Pt catalysts are effective for the selective cleavage of C-C bonds compared to C-O bonds in oxygenated hydrocarbons. In addition, the rate for C-C bond cleavage in alcohols is calculated to be much faster than the rate constant for C-C bond cleavage in alkanes on Pt catalysts. Calculations show that PtSn alloy catalysts exhibit lower rates of decomposition reactions compared to Pt catalysts, while hydrogenation/dehydrogenation reactions are unaffected. Thus, Sn alloying alters product selectivity.; The kinetic models describing oxygenate reactions over the catalysts are valuable for predicting catalytic behavior under different conditions, such as temperature, pressure, etc. Thus, conclusions from these studies can aid in improving catalyst design with regards to catalyst activity and selectivity. In addition, results from these studies can be used as a basis for studies on other catalysts, such as Ni, Ru, Pd and alloys of these catalysts.