10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Size-Controlled Synthesis of Pd Doped TiO2 Catalyst in a Flame Aerosol Reactor (FLAR) for Oxygen Removal from Carbon Dioxide Enriched Combustion Exhaust Gases
SUNGYOON JUNG, Pratim Biswas, Washington University in St Louis
Abstract Number: 325 Working Group: Materials Synthesis
Abstract To mitigate the level of CO2 emitted from the coal-fired combustion systems, an oxy-coal combustion system has been developed as a promising technique to effectively capture CO2 in power plants. The captured CO2 can be either sequestered [1] or reused for enhanced oil recovery (EOR) [2] or converted to value added products [3]. Although a highly concentrated CO2 stream was achieved in the combustion exhaust gas (~63%), it cannot be directly applied for EOR or sequestration because of a residual concentration of oxygen (O2) (~3%), which is greater than the requirement for EOR (<100ppmv) [4], and the strict requirement to prevent corrosion in the transportation pipeline (10 ppmv) [5]. To overcome this shortcoming, catalytic O2 removal system with hydrocarbons has been recently proposed. In this study, we developed a one-step synthesis method of Pd doped TiO2 catalysts for an efficient O2 removal by catalytic methane (CH4) oxidation reaction. To achieve this, we first synthesized Pd doped TiO2 catalysts with different Pd loading (1.3, 5.5, and 11.7%) in using flame aerosol reactor (FLAR). Flame synthesis has been extensively used as a gas phase technique that can produce homogeneous nanoparticles and can be scaled up for high throughput production. Second, we developed a differential fixed-bed reactor to test the O2 removal performance of the catalysts. The activity of synthesized catalysts was tested at temperatures ranging between 25 and 500 °C and under atmosphere pressure. When near stoichiometric condition (O2/CH4=2) was applied for the catalytic activity tests, enhanced conversion of O2 (~40%) was obtained at 400 °C with Pd (1.5%) doped TiO2 catalyst compared to that (~22%) with only TiO2 catalyst. In addition, O2 conversion increases with increasing Pd doping. The enhanced catalytic activity of Pd-doped TiO2 catalysts for O2 removal was supported by the structural properties of catalysts which are increasing rutile phase confirmed by X-ray diffraction and well-dispersed Pd clusters on TiO2 nanoparticles (~12 nm) revealed by transmission electron microscopy and energy-dispersive X-ray spectroscopy. This study highlights a new insight into an effective O2 removal by using flame-synthesized Pd-doped TiO2 catalysts to decrease the O2 concentration in flue gas emitted from oxy-coal combustion system.
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