(380bc) Improving CO2 Capture Efficiency in a Fluidized Bed of TiO2 Nanoparticles

Carbon Dioxide (CO₂) has been recognized as a major greenhouse gas among many other heat-trapping gases due to its relative abundance in the atmosphere. The US National Oceanic and Atmospheric Administration (NOAA) stated that global average concentrations of CO₂ surpassed 400 ppm in March 2015 for the first time since they started tracking carbon dioxide in the atmosphere [1]. The human activity that pumped carbon dioxide into the atmosphere over the past 150 years raised its levels higher than during the industrial revolution, which began in around 1850, i.e. higher than 280 parts per million CO₂ [2].

Carbon capture and storage (CCS) is a promising option for CO₂ reduction. Numerous methods to capture carbon dioxide have been proposed, including post-combustion carbon capture processes focusing on advanced solid adsorbents and fluidization/membrane systems. The use of a fluidized bed reactor is one of the promising techniques for CO₂ capture in a post-combustion process. The main benefits from fluidization are high gas–solids contact efficiency and the continuous regeneration of adsorbents. Li et al. [3] studied CO₂ adsorption capacity over dry K₂CO₃/MgO/Al₂O₃ adsorbents in a fluidized bed reactor. Li and Lu et al. [4,5] utilized enhanced calcium-based adsorbents for CO₂ capture since calcium-oxide containing materials have high reactivity and adsorption capacity for CO₂ and low material cost. Valverde et al. [6] mixed silica and calcium hydroxide powder to enhance the CO₂ adsorption efficiency in the fluidized bed.

In this work, a microjet and vibration assisted (MVA) fluidized bed that is a patent-pending technology by the Andino research group at Arizona State University [7] was developed to enhance the fluidization quality of nanosized TiO₂ particles. The behavior of the fluidized bed of TiO₂ nanopowders was studied to optimize operating conditions in order to achieve a high CO₂ capture efficiency. It was hypothesized that the higher fluidized bed height achieved by the novel MVA system would correspond to improvements in the CO₂ capture efficiency. The actual CO₂ concentrations and breakthrough time were measured at the outflow of the fluidized bed system. Results from the MVA system were compared to a simple vibrating fluidized bed (VFB) to examine the impact of bed height on CO₂ capture.

References

1. Roberto M. C., 2015 State of the Climate: Carbon Dioxide (2016)
2. Lindsey, R., Climate Change: Atmospheric Carbon Dioxide (2018)
3. Lei Li, Yong Li, Xia Wen, Feng Wang, Ning Zhao, Fukui Xiao, Wei Wei, and Yuhan Sun, CO₂ Capture over K2CO3/MgO/Al2O3 Dry Sorbent in a Fluidized Bed, Energy Fuels 25 (2011) 3835–3842.
4. Li L, King DL, Nie Z, Li XS, Howard C. MgAl2O4 spinel-stabilized calcium oxide absorbents with improved durability for high-temperature CO₂ Energy Fuels 24 (2010) 3698–3703.
5. Lu H, Smirniotis PG, Ernst FO, Pratsinis SE. Nanostructured Ca-based sorbents with high CO₂uptake efficiency. Chem Eng Sci. 64 (2009) 1936–1943.
6. Valverde JM, Pontiga F, Soria-Hoyo C, Quintanilla MAS, Moreno H, Duran FJ, Espin MJ. Improving the gas-solids contact efficiency in a fluidized bed of CO₂adsorbent fine particles. Phys Chem Chem Phys. 13 (2011) 14906–14909.
7. An, K. and Andino*, J.M., Microjet and Vibration Assisted Fluidization of Nanoparticles, US Patent and Trademark Office Provisional Patent application #62/815,653 filed on 8 March 2019. Invention disclosure #D19-073/M19-140P, Filed with Skysong Innovations at Arizona State University on 12 December 2018.