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

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 115 h lifetime test at 335 °C.

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.Figure optionsDownload as PowerPoint slideHighlights
► Ce0.5Pr0.5O2 is an active and stable catalyst for chlorinated VOC combustion.
► Ce0.5Pr0.5O2 activity was constant in a 115 h 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.