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Studying the relationship between electronic structure and activity helps to understand the catalytic mechanism since the catalytic combustion is a redox reaction dominated by electron transfer. Herein, we regulated the electron energy and O p-band center of La-based perovskite catalysts by a facile method of changing the B-site ion (B = Co, Mn, Fe). The crystal structure, morphology, reducibility, element valence distribution, and catalytic properties of prepared catalysts were characterized. Combining with DFT calculation, it was found that the low electron energy in (110) facets of LaCoO3/SiO2 catalyst contributes to the formation of reactive oxygen species and high-valence Co3+ ions. The highest oxygen adsorption activation capacity of LaCoO3/SiO2 originates from a moderate location of the O p-band center with respect to the Fermi level. As expected, the LaCoO3/SiO2 sample shows higher n-butylamine oxidation activity than that of LaMnO3/SiO2 and LaFeO3/SiO2. This work provides different insights into understanding the activity of La-based perovskite catalysts for oxidation reactions. [ABSTRACT FROM AUTHOR]

The RuO2@CemZr1−mO2−SiO2 catalysts were synthesized by the spontaneous deposition method. Based on the XRD patterns of various RuO2@CemZr1−mO2−SiO2 catalysts, it was suggested that the Ru noble metal nanoparticles were distributed with high dispersion on the surface of Ce‐modified porous matrix of ZrO2. H2‐TPR and NH3‐TPD confirmed that all catalysts possessed superior redox ability as well as acidity, which were facilitated to the catalytic dichloroethane (DCE) oxidation. From the systematic study of texture structure, surface properties and catalytic activity, we knew that acid sites were shown to be favorable for adsorption as well as activation of DCE and improve the anti‐poisoning property of the catalyst, and the redox ability could facilitate the further oxidation of the intermediate. The optimized RuO2@Ce0.1Zr0.9O2−SiO2 catalyst exhibited superior activity (T90=275 °C at a space velocity of 15000 h−1), good stability (at 300 °C for 50 h) and outstanding tolerance towards moisture (in 5 % moisture). Our work demonstrated the important role of acidity and redox ability over these functionalized catalysts, providing guidance for the advanced catalyst design. [ABSTRACT FROM AUTHOR]

In this study, highly‐dispersed perovskite‐type oxides LaMnxCo1‐xO3 supported on mesoporous SiO2 (LMxC1‐xO/SiO2) were synthesized by a citric acid‐assisted deposition method. For LMxC1‐xO/SiO2 catalysts, the double B‐site transition metal ions can not only significantly arise the surface defects, but also lead to the formation of (Mn3++Co3+)/(Co2++Mn4+) redox cycle, both of which were able to improve the catalytic performance of LMxC1‐xO/SiO2 in n‐butylamine combustion. Strikingly, LM0.2C0.8O/SiO2 catalyst showed the optimum catalytic performance (T90%=210 °C at a space velocity of 15,000 mL gcat−1 h−1) and the lowest NOx yield among the LMxC1‐xO/SiO2 samples, which could be greatly assigned to the accelerated activation and circulation of the oxygen species initiated by the surface defects and redox cycle. [ABSTRACT FROM AUTHOR]

• CeO 2 @SiO 2 catalysts were prepared by a spontaneous deposition method. • CeO 2 @SiO 2 exhibited high performance and durability in DCE catalytic oxidation. • The richer weak acid sites were beneficial to the adsorption and activation of DCE. • The abundant adsorbed oxygen species and oxygen mobility improved oxidation of DCE. The construction of uniform nanodots CeO 2 stabilized by porous silica matrix (CeO 2 @SiO 2 -T) was synthesized by a spontaneous deposition method. Based on the XRD and TEM results, the CeO 2 nanodots were highly dispersed on the porous silica matrix. The characterizations including O 2 -TPD, XPS, and NH 3 -TPD clarified that CeO 2 @SiO 2 -T catalysts possessed strong acidity, rich surface adsorbed oxygen species and oxygen mobility, which was beneficial to the improvement of adsorption and catalytic oxidation of 1,2-dichloroethane (DCE). The CeO 2 @SiO 2 -T catalysts exhibited high performance for DCE oxidation, in which the CeO 2 @SiO 2 -400 catalyst showed the best performance (T 90 = 275 °C at a space velocity of 15000 h−1) and good stability (at 295 °C for 100 h). The characterization and activity test results showed that the richer acid sites were beneficial to the adsorption and activation of DCE, contributing to the subsequent HCl removal and vinyl chloride (VC) formation. Noticeably, the weak acid sites were more favorable for the improvement of catalytic activity. Then major of VC would be oxidized to adsorbed acetate, which could be further decomposed to CO x and HCl. In addition, trace poly-chlorinated by-products were detected. The abundant surface adsorbed oxygen species and excellent oxygen mobility facilitated the further oxidation rather than the chlorination reactions. [ABSTRACT FROM AUTHOR]

Tuning the metal-support interaction is an effective strategy for improved catalytic performance in catalytic combustion of methane. Herein, we prepared Pd/LaMnO 3 catalysts using two types of LaMnO 3 , that were achieved by plasma treatment or traditional thermal treatment respectively. Contrast to the LaMnO 3 (LMO-T) support, the plasma-treated LaMnO 3 (LMO-P) support has large surface specific area, porosity and many surface defects. Among these catalysts, the Pd supported on plasma-treated LaMnO 3 (Pd/LMO-P) shows the best catalytic activity (T 90 = 471 °C) and the lowest E a value (74 kJ/mol). It reveals that the high performance should be attributed to the large surface area, surface-rich active species and strong metal-support interaction. The XPS techniques also demonstrated that the plasma-treated could boost the electron transfer between PdO x and LaMnO 3 , improving the redox properties. Moreover, the plasma-treated catalyst exhibits an excellent performance under thermal and water-vapor coexistence environment. The superior performance can arouse interest for the design of advanced catalyst in environmental catalysis. [Display omitted] • Porous perovskite oxides (LaMnO 3) are synthesized by plasma technique. • Plasma-treatment endows the LaMnO 3 support with high surface area and surface-rich oxygen vacancies. • The Pd/LMO-P catalyst shows the best catalytic combustion activity of CH 4. • The synergistic effect between PdO x and plasma-treated LaMnO 3 support is strengthened. [ABSTRACT FROM AUTHOR]

Ultrafine cobalt oxide nanoparticles embedded in porous SiO 2 matrix were facilely prepared by a spontaneous deposition method, which were applied to catalytic methane combustion. Owing to rich surface active oxygen and more active sites, the CoO x @SiO 2 -400 catalyst shows the highest catalytic activity. These structural catalyst also show high thermal stability and efficient moisture resistance. [Display omitted] • Ultrafine cobalt oxide nanoparticles embedded in porous SiO2 matrix were facilely prepared. • The CoOx@SiO2-400 catalyst with the smallest particle size (˜1.3 nm) shows the highest activity. • Rich surface adsorbed oxygen and more active sites contribute to higher activity. • These structural catalysts show high thermal stability and efficient moisture resistance. Ultrafine cobalt oxide nanoparticles embedded in porous SiO 2 matrix were facilely prepared by a spontaneous deposition method, which were applied to catalytic methane combustion. Among the serial of CoO x @SiO 2 -T catalysts, the CoO x @SiO 2 -400 catalyst with the smallest particle size (˜1.3 nm) has the highest activity, showing an obvious size-dependent activity. Based on the XPS, O 2 -TPD and H 2 -TPR analyses, it indicated that the CoO x @SiO 2 -400 catalyst possessed a higher ratio of surface absorbed oxygen and lattice oxygen (O ads /O latt) and more active sites, which enabled the enhancement of its catalytic activity. Compared with simply supported CoO x /SiO 2 -400 catalyst, the embedded CoO x @SiO 2 -400 catalyst show superior catalytic performance under dry/moisture conditions owing to silica encapsulation. As for possible CH 4 combustion mechanism, the intermediate of Co-formate is determined by in-situ DRIFTS. [ABSTRACT FROM AUTHOR]