(558af) One-Step Synthesis of Cobalt Oxide Catalyst in a Flame Aerosol Reactor for Oxygen Removal from CO2-Rich Oxy-Coal Combustion Flue Gas

To reduce the CO₂ level in the atmosphere, an oxy-coal combustion system has been developed to effectively capture CO₂ in power plants by achieving the concentrated CO₂ stream in its exhaust [1]. The concentrated CO₂ stream can be used for enhanced oil recovery (EOR). However, to be used for EOR, the O₂ concentration in the gas stream should be reduced to 100 ppmv to satisfy the standard for EOR [2]. Recent studies have applied a catalytic O₂ removal system with CH₄, and have achieved a high O₂ removal efficiency by using noble metal (e.g., Pd and Pt) doped metal oxide catalysts [3, 4]. Even though the noble metal doped metal oxide catalysts showed the high O₂ conversion, they have a limitation to be used in industry due to their high economic value. In this study, cobalt oxide catalysts were used as a promising substitute for O₂ removal, and their catalytic properties and activities for O₂ removal were investigated. A continuous one-step flame aerosol reactor (FLAR) is utilized in this study, and different conditions are used to synthesize different cobalt oxide catalysts. Previous studies have been reported that the flame profile significantly affects the catalytic properties of the synthesized catalysts and it could be varied by changing synthesizing conditions such as gas flow rates and a distance between a quench ring and a top of a burner [5, 6]. In this study, we use 1) different ratios between oxidant and fuel (oxidant/fuel=3.4~7.1) and 2) different distances between the quench ring and the top of burner (1.5~2.5 in) to control the flame profile. The detailed flame profiles are modeled by employing a computational fluid dynamics and CHEMKIN. The synthesized catalysts show different catalytic activities for O₂ removal. As the ratio between oxidant and fuel increases, the synthesized catalyst shows the higher O₂ conversion compared to the others. In addition, the distance between the quench ring and the top of burner increases, the high O₂ conversion is obtained with the synthesized catalyst. Our finding provides a promising ability of cobalt oxide catalysts for O₂ removal and reveals the effect of flame profile on controlling the catalytic activities of the synthesized catalysts for O₂ removal.

References:

[1] A. Gopan, B.M. Kumfer, J. Phillips, D. Thimsen, R. Smith, R.L. Axelbaum, Process design and performance analysis of a Staged, Pressurized Oxy-Combustion (SPOC) power plant for carbon capture, Appl Energ, 125 (2014) 179-188.

[2] DOE/NETL, Quality guidelines for energy system studies: CO₂ impurity design parameters, (2013).

[3] Q. Zheng, S. Zhou, M. Lail, K. Amato, Oxygen Removal from Oxy-Combustion Flue Gas for CO₂ Purification via Catalytic Methane Oxidation, Ind Eng Chem Res, 57 (2018) 1954-1960.

[4] A.N. Kuhn, Z. Chen, Y. Lu, H. Yang, Sequential oxygen reduction and adsorption for carbon dioxide purification for flue gas applications, Energy Technol-Ger, (2018).

[5] S.Y. Dhumal, T.L. Daulton, J. Jiang, B. Khomami, P. Biswas, Synthesis of visible light-active nanostructured TiO_x (x < 2) photocatalysts in a flame aerosol reactor, Appl Catal B-Environ, 86 (2009) 145-151.

[6] V. Tiwari, J. Jiang, V. Sethi, P. Biswas, One-step synthesis of noble metal-titanium dioxide nanocomposites in a flame aerosol reactor, Appl Catal a-Gen, 345 (2008) 241-246.