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

Abstract

The influence of the kind of A‐site cation in A1–xSrxMnO3 perovskites (A = La, Pr, Nd, Di [didymium]) on the catalytic activity in the total oxidation of methane, chloromethane, dichloromethane, and trichloroethylene has been studied. In contrast to methane, the total oxidation of chlorinated hydrocarbons (CHC) is connected with a reversible catalyst deactivation and the formation of byproducts at low reaction temperatures. For the catalysts calcined at 600 and 800 °C, resp., the catalytic activity is determined mainly by specific surface area, amount of oxide admixtures and crystallinity of the perovskite. DiMnO3 showed the highest and PrMnO3 catalysts the lowest catalytic activity in the total oxidation of methane and CHC. Partial substitution of A by Sr leads to an enhancement of the catalytic activity in the total oxidation of methane, but not in the total oxidation of CHC.

Nonthermal Plasma Abatement of Trichloroethylene Enhanced by Photocatalysis

“…For catalytic oxidation, a minimum TCE concentration of 1000 ppm is mandatory in order to maintain autothermal conditions. Catalytic destruction of 1000 ppm of TCE was reported over various acidic catalysts like H−Y zeolite, Al 2 O 3 , tungasta−alumina, and silica−alumina in the temperature range 400−650 °C with a selectivity to total oxidation ≈ 50−60%. − Likewise, bimetallic Cr−Cu-supported zeolites and Mn-containing perovskites in the temperature range 500−650 °C showed ∼60% CO 2 selectivity with poor carbon balance, giving many undesired byproducts. − Hence, there is a need for alternative methods since byproduct formation is unacceptable. During the present study (Figure ), ∼100% carbon balance toward CO x formation was achieved with the SIE ≈ 830 J/L.…”

“…[31][32][33][34] Likewise, bimetallic Cr-Cusupported zeolites and Mn-containing perovskites in the temperature range 500-650 °C showed ∼60% CO 2 selectivity with poor carbon balance, giving many undesired byproducts. [34][35] Hence, there is a need for alternative methods since byproduct formation is unacceptable. During the present study (Figure 4), ∼100% carbon balance toward CO x formation was achieved with the SIE ≈ 830 J/L.…”

Totaloxidation von Methan und chlorierten Kohlenwasserstoffen an A1–xSrxMnO3/ZrO2‐Trägerkatalysatoren

“…In einer Reihe von Arbeiten wurde über die Eigenschaften von Perowskit-Trägerkatalysatoren bei der Totaloxidation von KW [17 ± 19] und CKW [12,17] berichtet. F U J I I et al [18] untersuchten die katalytische Aktivität von La 1±x Sr x CoO 3 -Perowskiten auf einer Vielzahl von Metalloxiden als Träger für die Totaloxidation von Propan.…”

“…Didym (67,7 Ma.-% Nd 2 O 3 ; 21,6 Ma.-% Pr 6 O 11 ; 10,7 Ma.-% La 2 O 3 ) ist als billiges Seltenerdgemisch für die industrielle Nutzung von Perowskit-Katalysatoren interessant. In vorangegangenen Arbeiten[11,12] wurden analoge Untersuchungen an den ungeträgerten Katalysatoren durchgeführt. YSZ) mit den entsprechenden Nitratlösungen hergestellt.…”

“…Dies ist ein Hinweis darauf, dass Sr-Ionen zumindest teilweise in das Perowskitgitter eingebaut wurden. Das Ergebnis ist in Übereinstimmung mit Untersuchungen an ungeträgerten Perowskiten[7,12,14,15].Tabelle 2.Oberflächenzusammensetzung c i (Atom-%) der 5 Mol-% LaMnO 3 /ZrO 2 -Trägerkatalysatoren in Abhängigkeit von der Calcinierungstemperatur T Calc. (C).…”