Activity, selectivity and stability of praseodymium-doped CeO2 for chlorinated VOCs catalytic combustion

• Published in: Applied catalysis. B, Environmental Environmental, 2012-06, Vol.121-122, p.162-170
• Main Authors: de Rivas, B., Guillén-Hurtado, N., López-Fonseca, R., Coloma-Pascual, F., García-García, A., Gutiérrez-Ortiz, J.I., Bueno-López, A.
• Format: Article
• Language: English
• Subjects: 1,2-Dichloroethane; Catalysis; Catalysts; Cerium–praseodymium mixed oxide; CexPr1−xO2; Chemistry; Chlorinated VOC combustion; Chlorination; Combustion; Deactivation; Exact sciences and technology; General and physical chemistry; Stability; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Volatile organic compounds; X-rays
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2012.03.029

Pure and mixed oxides of Ce and/or Pr were prepared and evaluated for the catalytic combustion of 1,2-dichloroethane. Ce0.5Pr0.5O2 is the most active and stable catalyst, while other formulations suffer deactivation by chlorination. [Display omitted] ► Ce0.5Pr0.5O2 is an active and stable catalyst for chlorinated VOC combustion. ► Ce0.5Pr0.5O2 activity was constant in a 115h VOC-Cl combustion test at 350°C. ► Ce0.5Pr0.5O2 activity was constant after three VOC-Cl combustion tests (150–500°C). ► Pure and mixed oxides with Ce:Pr ratio different to 1 suffer partial deactivation. ► Deactivation is attributed to chlorination. Ce–Pr mixed oxides, namely Ce0.8Pr0.2O2, Ce0.5Pr0.5O2 and Ce0.2Pr0.8O2, were prepared by conventional coprecipitation and evaluated for the catalytic combustion of 1,2-dichloroethane, which was selected as a model reaction for chlorinated VOC abatement. For comparison purposes, the pure oxides were also prepared and catalytically tested. A certain decrease in catalytic activity was observed after three consecutive temperatures cycles from 150 to 500°C for all catalysts, except for Ce0.5Pr0.5O2. This deactivation was particularly noticeable for pure praseodymia and Ce0.2Pr0.8O2, while Ce0.8Pr0.2O2 and Ce0.5Pr0.5O2 exhibited a superior stability. The catalysts deactivation was attributed to bulk and/or surface chlorination, as revealed by X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy. Interestingly, the Ce0.5Pr0.5O2 mixed oxide, which converted the chlorinated feed at the lowest temperature due to its substantial resistance to chlorination, showed a constant activity in a 115h lifetime test at 335°C.