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Series of α, β, γ, δ type MnO2 supported on LaMnO3 perovskite was developed by a one-pot synthesis route. Compared with α-MnO2, β-MnO2, γ-MnO2, δ-MnO2 and LaMnO3 oxides, all MnO2/LaMnO3 showed promotional catalytic performance for toluene degradation. Among them, α-MnO2/LaMnO3 holds the best active and mineralization efficiency. By the analysis of N2 adsorption-desorption, XPS and H2-TPR, it can be inferred that the improved activity should be ascribed to the higher proportion of lattice oxygen, better low-temperature reducibility and larger specific surface area. Besides, the byproducts from the low-temperature reaction of toluene oxidation were detected by a TD/GC-MS, confirming the presence of the intermediates. Combined with the in-situ DRIFTS, the catalytic degradation path of toluene oxidation has also been discussed in depth. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • γ-MnO 2 /SmMnO 3 catalyst was prepared by an in situ etching method. • The catalyst showed superior activity for BETX removal at high WHSV and moisture. • The inner principle of VOCs oxidation was revealed by a dynamics investigation. • The strategy is low cost, scalable and efficient. Abstract γ-MnO 2 , SmMnO 3 , and γ-MnO 2 /SmMnO 3 catalysts were prepared by facile methods, wherein the SmMnO 3 (SMO) perovskite was synthesized through one-step calcination and the γ-MnO 2 /SmMnO 3 was formed by an in situ growth of γ-MnO 2 on the surface of SMO. These materials ware characterized by XRD, SEM-mapping, N 2 -adsorption, XPS and H 2 -TPR to investigate their textural properties. Compared with that of SMO and γ-MnO 2 , the γ-MnO 2 /SMO shows better performance for catalytic oxidation of aromatic VOCs in wet air (10 vol. %), which may be attributed to its higher surface molar ratio of lattice oxygen to adsorbed oxygen (O latt /O ads) and better low-temperature reducibility. Besides, for γ-MnO 2 /SMO catalyst, a successive oxidation route and the inner principle of BETX (benzene, ethylbenzene, toluene, and o-xylene) oxidation were also revealed via various tests and a comprehension of dynamics investigation. Meanwhile, the experiments under simulated realistic exhaust conditions displayed that the γ-MnO 2 /SmMnO 3 is also a good catalyst with high stability for aromatic VOCs oxidation, and fulfilled endurability to high humidity (20 vol.%). [ABSTRACT FROM AUTHOR]

Perovskite-type oxide of SmMnO 3 sheet with mesoporous structures was successfully synthesized for the first time by a simple one-step calcination. Citric acid was utilized as the propellant for the construction of SmMnO 3 perovskite structure and the mesoporous formation. The characterization results showed that a large number of mesoporous were evenly distributed into the SmMnO 3 perovskites sheets by the effect of citric acid. The as-prepared catalyst showed superior catalytic activity and stability for toluene oxidation; the toluene conversion kept ca. 99.9% at 240 °C during the reaction of 36 h. This work could supply an impactful technique to prepare high catalytic activity of ABO 3 perovskites with mesoporous structure for the practical applications. [ABSTRACT FROM AUTHOR]

Tuning the profile of acid sites and defective structure on the surface of redox-active metal oxide is a potential method to establishing efficient catalysts for the catalytic oxidation of chlorinated VOCs. Herein, employing chlorobenzene oxidation as the reaction model, we report that Brønsted acid sites and oxygen vacancies can be simultaneously introduced to the surface of Sm-Mn perovskite (SMO) through phosphomolybdic-acid (PMo)-mediated hybridization, which can effectively inhibit the poisoning of chlorine species to the active metals by inducing C-Cl bond cleavage at Brønsted acid sites, while removing some rare earth of Sm to increase the content of the active oxygen species by in-situ dismutation, thus enhancing the activity of the catalyst for chlorobenzene oxidation. The physicochemical properties of the synthesized catalysts were determined by XRD, SEM-Mapping-EDS, N 2 adsorption-desorption, Py-IR, NH 3 -TPD, O 2 -TPD and H 2 -TPR. Compared with that of SMO, the SMO-PMo catalyst can perform a more stable chlorobenzene conversion of 98% over 16 h at 300 °C. Meanwhile, the crystal structure and composition of SMO-PMo after catalytic reaction was similar to that before catalytic reaction, indicating that its structure is relatively stable. Our work could guide future construction of advanced catalysts for the removal of chlorinated VOCs. [Display omitted] • Catalyst is functionalized by one-step phosphomolybdic-acid-mediated hybridization. • Active oxygen species are increased by in-situ dismutation. • Cl poisoning is inhibited by inducing C-Cl bond cleavage at Brønsted acid sites. • The stability of the catalyst for chlorobenzene oxidation is notable enhanced. [ABSTRACT FROM AUTHOR]

[Display omitted] • GdCoO 3 was formed via a stepwise calcination using viscous mixture. • The viscous state facilitates uniform mixing of the raw material. • GdCoO 3 shows remarkable reducibility, notable oxygen species, and good activity. • The preparation was affordable, reliable, and easily scalable. Grape-like GdCoO 3 perovskite was synthesized through a straightforward one-step method. In this process, the combined raw materials were lightly dampened with a minute quantity of water to form a viscous state and subsequently subjected to a single-step calcination, resulting in the formation of the perovskite structure, all without the need for additional procedural steps. The characterization results indicated the presence of abundant reactive oxygen species distributed on the surface of GdCoO 3. Most notably, the catalyst prepared in this manner exhibited remarkable catalytic activity for VOC oxidation. [ABSTRACT FROM AUTHOR]