查看更多>>摘要：? 2022 Elsevier B.V.Cu-based catalysts are critical for the oxidation of hydrogen chloride (HCl) to chlorine, but they have low stability at high temperatures. In this study, the Cu/aUiO-66-NH2 catalyst was synthesized by an amorphous zirconium-based metal-organic framework (denoted by aUiO-66-NH2). Not only did the catalyst show higher activity (1.96 times that of CuO/Al2O3), but it also showed enhanced stability (no less than 100 h). Cu(0) and Cu(OH)2 were highly dispersed and evolved into partially chlorinated copper species during the reaction process, as revealed by X-ray diffraction, X-ray photoelectron spectroscopy, and scanning transmission electron microscopy. The interval XPS characterizations performed during the 100-hour reaction process showed that Cu/aUiO-66-NH2 had self-limited chlorination with a maximum chlorine capacity of approximately 19.60%. Additionally, the temperature-dependence experiment showed that the activation energy of Cu/aUiO-66-NH2 was 81.63 kJ/mol during HCl oxidation to chlorine.
查看更多>>摘要：? 2022 Elsevier B.V.This study analyses the effect of the nanoscale intimacy of Pt metal and Br?nsted acid sites on the hydroisomerization of n-pentane and n-hexane using a series of zeolite/binder composite catalysts with Pt located outside or inside of the zeolite crystal and with Pt dispersed in the zeolite crystal and its vicinity on the binder. Analysis of the conversions of n-pentane and n-hexane to branched isomers and Cn≤4 byproducts under the relevant conditions of the process showed that the highest activity is obtained for catalysts with high proximity of acid and Pt sites dispersed in the zeolite crystal together with Pt on the binder surrounding the zeolite crystals. Such an arrangement allows the hydrogenation/dehydrogenation of alkanes in close proximity to the Br?nsted sites, allowing the full functionality of acid sites and limiting the diffusion of intermediate alkenes between Pt sites.
查看更多>>摘要：? 2022 Elsevier B.V.It is desirable but challenging to explore non-noble metal based catalyst for the solvent-free aerobic oxidation of benzyl alcohol to benzaldehyde. LayCo1Ox was prepared through a co-precipitation method, which exhibited excellent catalytic performance for titled reaction with a yield of 73.1% and selectivity of 99.6%. Introduction of La in the Co3O4 can modify the electronic property of Co, improving the surface Co3+ content and enhancing the activity. The synergistic effects of La and Co in the bimetallic catalysts are kinetically discussed. In addition, the kinetic and experimental studies revealed that the generated water favors the selectivity but suppresses the activity for the titled reaction. It is found that good activity and excellent selectivity for the (heterocyclic)aromatic alcohols aerobic selective oxidation over the bimetallic catalyst were obtained.
查看更多>>摘要：? 2022 Elsevier B.V.The phenol hydrogenation is a green strategy for preparing cyclohexanone. The key challenge is to develop efficient catalysts. Herein, composite carbon nanofibers (CNFs) with a core-shell structure were fabricated, where ZIF-L-Co/PAN composite nanofibers were prepared by electrospinning and in-situ growth, and used as the precursor. The Pd@CNFs catalysts were synthesized by the Pd loading and applied for the phenol hydrogenation. The as-fabricated Pd@CNFs-0.3 catalyst shows superior catalytic performance, and its turnover frequency (TOF) is 59.5 h?1, which is 2.3 times that of the PAN-derived Pd@CNFs-0 catalyst and 4.9 times that of the powdered ZIFs-derived Pd@CN-0.3 catalyst. The synergistic effect of carbon nanofibers core and ZIFs-derived shell layer carbon leads to high Pd loading, enhanced phenol adsorption capacity, and fast electron and mass transfer, which together contribute to the superior catalytic performance of Pd@CNFs-0.3. Moreover, because of the unique one-dimensional nanofiber structure, Pd@CNFs-0.3 shows good recovery and reusability in the phenol hydrogenation.
查看更多>>摘要：? 2022 Elsevier B.V.Platinum is widely investigated as co-catalysts for photocatalytic degradation of volatile organic compounds but studies seldom focus on their visible light sensitizing properties. Herein, Pt sensitizers of different oxidation states (0, II, IV) were modified on brookite TiO2 nanorods and investigated for acetaldehyde degradation under visible light. Pt(II) oxide/TiO2 showed the best photocatalytic activity but its stability was compromised by its self-oxidation to Pt(IV) during photo-oxidation reaction. Surface modification of an Fe(III) oxide thin film sensitizer layer around the Pt(II) oxide sensitizer was found to enhance both the stability and activity of Pt(II) oxide/TiO2. In situ double beam photoacoustic spectroscopy (DB-PAS) supported by DFT modeling showed the rapid injection of photoexcited electrons from Fe(III) oxide to Pt(II) oxide promote the stability of Pt(II) oxide, leading to enhanced performance. The findings provide guidance for the rational design of visible light-active metal oxide sensitizers for oxidative removal of indoor air pollutants.
查看更多>>摘要：? 2022 Elsevier B.V.A series of Ni-Fe bimetallic catalysts supported on high surface area of Ce0.8Zr0.2O2 (CZ) and SiO2 (S) were prepared by impregnation (10 wt% of metal charge) with different Ni:Fe ratios (10:0, 9:1, 3:1 and 1:1) and the effect of Fe content on promotion of CO2 methanation was investigated. Hydrogen reduction favors Fe incorporation into the Ni structure, forming Ni1?xFex alloys, whereas some Fe-O species remain unreduced. Ni-Fe/CZ catalysts showed a promoted reducibility at low temperature as well as high density of weak and medium basic sites in comparison with Fe-Ni/S catalysts. Activity tests revealed that CO2 conversion and CH4 selectivity increases with the decrease of Fe content. In the bimetallic catalysts, the presence of unreduced Fe-O species restricts the contact between hydrogen supplied by Ni1?xFex and adsorbed CO2. Superior activity of Ni/CZ was associated to the close location of medium basic sites and Ni nanoparticles to activate hydrogen. Microstructural studies of Ni/CZ catalyst after prolonged operation demonstrated the absence of carbon deposition and good Ni availability on the CZ surface.
查看更多>>摘要：? 2022 Elsevier B.V.Developing high-performance catalyst is of paramount importance for NO direct decomposition. Here, composite catalysts BaMnO3-CeO2 were designed and prepared by the one-pot method, which show high catalytic activity, oxygen resistance and durability. The NO conversion to N2 of 85.9% at 800 °C is achieved over 5%BaMnO3-CeO2. It exhibits 66.5% activity in the presence of 10 vol% O2 and runs stable for more than 200 h in 5 vol% O2 at 800 °C. The high performance is originated from the strong interaction between BaMnO3 and CeO2 components, where CeO2 can effectively inhibit the sintering of BaMnO3 particles, enhance the redox activity, mobility of lattice oxygen and NO sorption. The proposed catalytic mechanism based on diffuse reflectance infrared Fourier transform spectroscopy and kinetic study reveals that the formation of N2O* intermediate species is the rate determining step. BaMnO3-CeO2 composite can be a promising catalyst candidate for NO direct decomposition.
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