Total Oxidation of Chlorinated Hydrocarbons on A1–xSrxMnO3 Perovskite-Type Oxide Catalysts– Part I: Catalyst Characterization

Abstract

Thermoanalytical measurements (DTG‐DTA‐MS), X‐ray diffraction (XRD), temperature‐programmed reduction (TPR), redox titration and X‐ray photoelectron spectroscopy (XPS) were used to characterize A1–xSrxMnO3 perovskite catalysts (A = La, Nd, Pr, Di [didymium]). The catalyst samples were investigated before and after interaction with chloromethane in the temperature range between 300 and 650 °C. XRD and TPR measurements revealed the presence of oxide admixtures in samples calcined at 600 and 800 °C, resp., in air. Crystallinity of the samples and the amount of oxide admixtures depend on the kind of A‐site cations. Interaction of the perovskite samples with chlorinated hydrocarbons at reaction temperatures leads to a decrease of the specific surface areas; the perovskite structure is preserved. Redox titration and TPR measurements showed that the Mn(IV) content in the perovskites increases by partial substitution of La by Sr and decreases after interaction with chloromethane.

Total Oxidation of Chlorinated Hydrocarbons on A1–xSrxMnO3 Perovskite-Type Oxide Catalysts– Part II: Catalytic Activity

“…The properties of the calcined catalysts were studied in fresh state and after interaction with chloromethane under reaction conditions [1].…”

“…Perovskites calcined at 600 and 800 C, resp., exhibit relatively high specific surface areas, are poorly crystallized or X-ray amorphous and contain different amounts of oxide admixtures in dependence on the calcination temperature [1]. The lower catalytic activity of the perovskites calcined at 800 C is caused by their lower specific surface areas.…”

“…In part I of this paper [1] it was reported about the textural and structural characterization of A 1±x Sr x MnO 3 perovskitetype oxides. Preceding studies about the catalytic properties of perovskite-type catalysts have shown that the total oxidation of CHC on perovskite-type oxides is connected with a catalyst deactivation in the initial reaction period depending on the reaction temperature, residence time, kind and concentration of CHC in the feed.…”

“…were used. The preparation of the catalysts is described in [1]. For didymium the abbreviation Di is used in the following.…”

CO and H2 oxidation over Pt/BaSnO3 catalysts

“…They attract great attention as catalysts for many oxidation processes, for example, total oxidation of hydrocarbons (methane, propane) [2,3], chlorinated hydrocarbons [4,5] and ammonia [6], being therefore proposed as an economical substitute for noble metal-based catalysts. They are also efficient catalysts for the oxidation of carbon monoxide [7][8][9].…”