Search

Two‐component catalysts have garnered significant attention in the field of catalysis due to their ability to inhibit Ni sintering. In the present work, honeycomb‐structuralstructured Al2O3‐supported Ni and B were prepared to enhance coke tolerance during dry reforming of methane (DRM). Transmission electron microscopy (TEM) results revealed that the average particle sizes on Ni/Al2O3 and Ni‐0.16B/Al2O3 were 7.6 nm and 4.2 nm, respectively, indicating that B can effectively inhibit Ni sintering. After a 100‐hour reaction, the conversion of CH4 and CO2 on Ni/Al2O3 decreased by approximately 5 %, whereas on Ni‐0.16B/Al2O3, there was no significant decrease in CH4 and CO2 conversion, with values of approximately 81.6 % and 87.2 %, respectively. In situ DRIFT spectra demonstrated that Ni‐0.16B/Al2O3 enhanced the activation of CO2, thus improving the catalyst's stability. A Langmuir–Hinshelwood–Hougen–Watson (LHHW) model was developed for intrinsic kinetics, and the resulting kinetic expressions were well‐fitted fit to the experimental data, with R2 values exceeding 0.9. ActivationThe activation energies were also calculated. The outstanding stability of Ni‐0.16B/Al2O3 can be attributed to its stable honeycomb structure and B′s ability to significantly inhibit Ni sintering, reduce catalyst particle size, and enhance coke tolerance. [ABSTRACT FROM AUTHOR]

The construction of semiconductor heterojunctions is an effective strategy to improve the photocatalytic degradation efficiency of organic pollutants. Herein, ZnPc/BiVO4 Z-scheme heterojunction was synthesized via a physical mixing method and was used for the photocatalytic degradation of tetracycline (TC) under visible light irradiation. Compared with BiVO4 and ZnPc, the 15ZnPc/BiVO4 sample exhibited improved light absorption capacity, and the electron-hole separation efficiency and redox capacity were enhanced due to the formation of the Z-scheme heterojunction. The 15ZnPc/BiVO4 composite exhibited an optimal TC degradation rate of 83.1% within 120 min. Additionally, 15ZnPc/BiVO4 exhibited excellent stability in cycling experiments, which maintained a high TC degradation rate of 79.5% after four cycles. Free radical trapping experiments indicated that superoxide radicals (·O2−) were the main active substances in the photocatalytic degradation of TC. [ABSTRACT FROM AUTHOR]

Selective oxidation is one of the primary methods used to synthesize high‐value‐added oxygen‐containing organic compounds from alkenes. In particular, the selective oxidation of natural cinnamaldehyde has gained prominence as one of the main routes to produce natural benzaldehyde, which is in short supply in the global spice market. In this study, FeSBA catalysts were synthesized by supporting Fe2O3 onto the surface of spherical SBA‐15 using pore‐induced deposition for the selective oxidation of cinnamaldehyde to benzaldehyde. The Fe2O3 supporting increased the specific surface area of SBA‐15 by approximately eightfold and significantly improved the utilization efficiency of the reaction sites on Fe2O3. Additionally, the formation of Fe−O−Si bonds by Fe2O3 and SBA‐15 promoted the generation of weak‐acidic sites on the catalyst surface, significantly increasing the oxygen‐physisorption capacity of Fe2O3. Furthermore, quenching experiments confirmed the generation of significant amounts of O2− and singlet‐oxygen species on the FeSBA surface. Theoretical calculations confirmed that the physisorption and chemisorption of cinnamaldehyde and oxygen, respectively, on the FeSBA surface promoted the formation of a tetrameric intermediate. These results contribute significantly to research on the selective oxidation theory of α,β‐unsaturated aldehydes to aldehydes using oxygen and could guide future studies aimed at elucidating and improving the process. [ABSTRACT FROM AUTHOR]

To develop efficient catalysts for CO2 hydrogenation to dimethyl ether, Cu–Al2O3–TiO2–Ti3C2/HZSM-5 bifunctional catalysts were prepared by the surfactant PVP-assisted coprecipitation. The influence of Ti3C2 on Cu–Al2O3-based catalysts was investigated. The characterization results revealed that slight oxidation of the Ti3C2 surface generated highly dispersed TiO2 nanoparticles that the doping of TiO2‒Ti3C2 in the Cu‒Al2O3 catalyst increased the specific surface area of the catalyst and promoted the formation and growth of Cu nanoparticles, and that strong interactions occurred between TiO2‒Ti3C2 and the Cu components. The number of oxygen vacancies at the interface between TiO2‒Ti3C2 and Cu increased by 17%, and the electronic kinetic energy of Cu0 decreased by 0.1 eV, with the electron-rich oxygen vacancies transferring electrons to Cu2+ ions and maintaining more Cu species in lower oxidation states. Reactions were carried out at 260 °C and 3.0 MPa with a gaseous hourly space velocity (GHSV) of 1500 cm3‧g−1‧h−1 using Cu–Al2O3–TiO2–Ti3C2/HZSM-5 with 5.0 wt% Ti3C2 as the hydrogenation catalyst, which provided a CO2 conversion of 26.8% with 57.8% selectivity for DME. [ABSTRACT FROM AUTHOR]

A heterogeneous CoB/Nb2CTx catalyst was successfully prepared by in situ wet reduction of Co metal ions electrostatically adsorbed on the surface of Nb2CTx and applied to the selective hydrogenation of cinnamaldehyde (CAL). The 10 wt% CoB/Nb2CTx catalyst exhibited superior catalytic activity with a CAL conversion of 90.4% and a cinnamyl alcohol (COL) selectivity of 75.4%, while unsupported CoB showed a CAL conversion of only 24%. The characterization results showed that CoB was dispersed on the surface and in the Nb2CTx layers, and CoB/Nb2CTx exposed more effective active sites than CoB alone, leading to higher hydrogenation activities. In addition, the transfer of electrons from B to Co increased the electron density of Co, which rejects the adsorption on the C=C bond. A strong electronic effect existed between the dispersed surface CoB and Nb2CTx, and B contributed electrons to Nb2CTx, resulting in the formation of more electron-deficient B species, which serve as electrophilic sites for C=O adsorption. Moreover, Lewis acid sites on the surface of Nb2CTx were conducive to the adsorption of C=O bonds. The electron-deficient B and the Lewis acid site on the surface of CoB/Nb2CTx promoted the adsorption of C=O, resulting in a high yield of COL from CoB/Nb2CTx. [ABSTRACT FROM AUTHOR]