To reduce the CO
2 level in the atmosphere, an oxy-coal combustion system has been developed to effectively capture CO
2 in power plants by achieving the concentrated CO
2 stream in its exhaust [1]. The concentrated CO
2 stream can be used for enhanced oil recovery (EOR). However, to be used for EOR, the O
2 concentration in the gas stream should be reduced to 100 ppmv to satisfy the standard for EOR [2]. Recent studies have applied a catalytic O
2 removal system with CH
4, and have achieved a high O
2 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 O
2 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 O
2 removal, and their catalytic properties and activities for O
2 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 O
2 removal. As the ratio between oxidant and fuel increases, the synthesized catalyst shows the higher O
2 conversion compared to the others. In addition, the distance between the quench ring and the top of burner increases, the high O
2 conversion is obtained with the synthesized catalyst. Our finding provides a promising ability of cobalt oxide catalysts for O
2 removal and reveals the effect of flame profile on controlling the catalytic activities of the synthesized catalysts for O
2 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 TiOx (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.