High Performance Catalysts BaCoO₃−CeO₂ Prepared by the One‐Pot Method for NO Direct Decomposition

Abstract

NO direct decomposition is the most promising but also the most challenging approach for nitrogen oxides mitigation. Developing high performance catalysts is greatly desirable to promote the application of this technology. The present catalysts BaCoO3−CeO2 prepared by the one‐pot method show superior activity towards NO direct decomposition, robust oxygen resistance and decent durability. The NO conversion to N2 of 5 %BaCoO3−CeO2 catalyst is 57.2 %, 70.1 % and 75.6 % at 700, 750 and 800 °C, respectively. It still maintains at 54.3 % even in the presence of 10 vol % O2 at 800 °C and is stable in 1 vol % O2 at least for 24 h at 750 °C. Such impressive performance is ascribed to the unique properties of CeO2, strong interaction between perovskite and CeO2, and microstructure of the catalysts rendered by the citric acid‐nitrate one‐pot method.

Tuning the Catalytic Activity of Complex Metal Oxides Prepared by a One-Pot Method for NO Direct Decomposition

“…Generally, there are two types of oxygen species being desorbed from ABO 3 and A 2 BO 4 in terms of oxygen adsorbed at oxide ion vacancies (α oxygen) and lattice oxygen (β oxygen); both are important for NO direct decomposition. 19,23 As shown in Figure 7, the desorption peaks at ∼500 °C are derived from α oxygen in x = 10−60% and 10% LaSrCo 0.8 Fe 0.2 O 4 /MgO samples, which decreases to ∼200 °C in LSCF5582 and 80% La−Sr−Co−Fe/MgO and the area increases, indicating a higher content of oxide ion vacancies in the latter samples. The desorption peaks of lattice oxygen (>800 °C) shift to higher temperature with x in xLa−Sr−Co− Fe/MgO (x = 10−60%), which indicates that the phase transformation from A 2 BO 4 to ABO 3 decreases the mobility of lattice oxygen, leading to decreased activity with increased x for xLa−Sr−Co−Fe/MgO (x = 10−60%) samples.…”

“…The reduction of Co and Fe species in ABO 3 and A 2 BO 4 is a multi-step process. 23,46 The reduction peaks below 500 °C are mainly ascribed to the reduction of Co 3+ → Co 2+ and Fe 3+ → Fe 2+ , and those above 500 °C are ascribed to the reduction of Co 2+ → Co 0 and Fe 2+ → Fe 0 . The peak temperature reflects the reducibility, and the peak area represents the total amount of H 2 consumed.…”

“…It is 58% after 24 h. The decreases in activity are probably related with the sintering of the catalysts at elevated temperatures. 23 However, the crystalline structure remains unchanged. Besides LaSrCo 0.8 Fe 0.2 O 4 and MgO, no additional phase is detected by XRD, confirming the structural stability of the 10% La−Sr−Co−Fe/MgO catalyst.…”

“…The xLa−Sr−Co−Fe/MgO (x = 10, 20, 40, 60, and 80%, the total weight of La−Sr−Co−Fe and MgO is 100%) catalysts were prepared by the citric acid− nitrate one-pot method. 23 All the metal nitrates including Mg(NO 3 ) 2 were dissolved in deionized water. Ethylenediaminetetraacetic acid (EDTA) and citric acid were then added as the complexing agent.…”

“…21,22 The resultant materials show higher performance owing to the more uniform distribution of components. Our very recent work 23 shows that BaCoO 3 −CeO 2 catalysts prepared by the citric acid−nitrate method show superior activity toward NO direct decomposition and robust oxygen resistance, which is attributed to the strong interaction between the two components and unique microstructure of the catalysts rendered by the one-pot method.…”