A review and comparison of the reaction kinetics of the catalytic oxidation of PCDD/Fs and model compounds

Due to convenience and toxicity, the development of active catalysts for the catalytic oxidation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) typically relies on research conducted on model compounds in place of PCDD/Fs. The comparability between experiments conducted on PCDD/Fs and model compounds is however unresolved, questioning the design of catalysts for PCDD/F removal by conducting experiments with model compounds. For this reason, the current literature on catalytic destruction of PCDD/Fs and model compounds is reviewed and analyzed. A review of reaction kinetics indicates that similar effects are induced for the catalytic oxidation of PCDD/Fs and model compounds by changes in the gas phase composition, with few deviations. Based on the review of reaction kinetics, a first-order rate expression with respect to PCDD/F or model compound was selected and used to extract activation energies (Ea) and rate constants at 200 °C (k200) for 5 data sets of PCDD/F and 265 data sets for model compounds. It was found that V2O5/TiO2-based catalysts are the most studied catalyst formulation and generally achieve higher k200 than the other non-precious metal catalyst formulations. Comparing the kinetic parameters for the different model compounds and PCDD/Fs reveals that catalytic oxidation of PCDD/Fs has significantly lower Ea and significantly higher k200 compared to commonly used model compounds. It is evident that more laboratory research on catalytic oxidation of PCDD/Fs is required in order to establish the relevance of using model compounds for optimizing catalysts for PCDD/F oxidation, whereas it is established that kinetics for catalytic oxidation of PCDD/Fs only can be developed using actual PCDD/Fs at realistic operating conditions. [Display omitted] •Most research on catalytic oxidation of dioxins are conducted using model compounds.•Current research does not confirm resemblance between model compounds and dioxins.•Kinetics of the catalytic oxidation of model compounds and dioxins are very different.•Inlet concentration influences the catalytic oxidation of PCDD/Fs and model compounds.•Experiments with dioxins are required to asses the applicability of model compounds.