A comparison between the four Geldart groups on the performance of a gas-phase annular fluidized bed photoreactor for volatile organic compound oxidation
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Heterogeneous photocatalytic oxidation (PCO) is a widely studied alternative for the elimination of volatile organic compounds (VOC) in air. In this context, research on novel photoreactor arrangements to enhance PCO rates is desired. Annular fluidized bed photoreactors (AFBPR) have yielded prominent results when compared to conventional thin film reactors. However, very few works aimed at optimizing AFBPR operation. In this study, TiO2 photocalytic agglomerates were synthesized and segregated in specific size distributions to behave as Geldart groups A, B, C, and D fluidization. The TiO2 agglomerates were characterized by XRD, FTIR spectra, and N2 adsorption. Photocatalyst performances were compared in a 10-mm gapped AFBPR for degrading the model pollutant methyl-ethyl-ketone (MEK), using a 254-nm radiation source. Geldart group C showed to be inadequate for AFBPR operation due to the short operation range between fluidization and elutriation. In all the cases, photocatalytic reaction rates were superior to sole UV photolysis. Group A and group B demonstrated the highest reaction rates. Considerations based on mass transfer suggested that the reasons were enhanced UV distribution within the bed at lower flow rates and superior catalyst surface area at higher flow rates. Results also revealed that groups A, B, and D perform equally per catalyst area within an AFBPR if the fluidization numbers (FN) are high enough.
KeywordsAir treatment Photocatalysis VOC Fluidized bed Geldart group Methyl-ethyl-ketone
The authors express their gratitude to the Coordination for the Improvement of Higher Level Personnel (CAPES, Brazil), the National Council for Scientific and Technological Development (CNPq, Brazil), and the São Paulo Research Foundation (FAPESP, grant PIPE no 2016/00953-6) for the financial support. We are also grateful to Prof. Sergio Brochsztain from the Federal University of ABC for his help with the BET analysis.
- Braun AM, Maurette MT, Oliveros E (1991) Photochemical technology. Wiley, New YorkGoogle Scholar
- Costa-Filho BM, Araujo ALP, Silva GV, Boaventura RAR, Dias MMD, Lops JCB, Vilar VJP (2017) Intensification of heterogeneous TiO2 photocatalysis using an innovative micro-meso-structured-photoreactor for n-decane oxidation at gas phase. Chem Eng J 310:331–341. https://doi.org/10.1016/j.cej.2016.09.080 CrossRefGoogle Scholar
- Faghri A, Zhang Y, Howell JR (2010) Advanced heat and mass transfer. Global Digital Press, ColumbiaGoogle Scholar
- Fogler HS (2004) Elements of chemical reaction engineering. Prentice-Hall of India Private Limited, New DelhiGoogle Scholar
- Korologos CA, Nikolaki MD, Zerva CN, Philippopoulos CJ, Poulopoulos SG (2012) Photocatalytic oxidation of benzene, toluene, ethylbenzene and m-xylene in the gas-phase over TiO2-based catalysts. J Photochem Photobiol A Chem 244:24–31. https://doi.org/10.1016/j.jphotochem.2012.06.016 CrossRefGoogle Scholar
- Kunii D, Levenspiel O (1991) Fluidization engineering. Butterworth-Heinemann, BostonGoogle Scholar
- Sing KSW, Everett DH, Haul RAW, Moscou L, Pierotti RA, Rouquérol J, Siemieniewska T (1984) Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity. Pure & Appl Chem 57 (4): 603–619. doi: https://doi.org/10.1351/pac198557040603
- USEPA (2016) National enforcement initiative: cutting hazardous air pollutants. EPA Web https://wwwepagov/enforcement/national-enforcement-initiative-cutting-hazardous-air-pollutants Acessed 18 December 2017