A Robust Au/ZnCr2O4 Catalyst with Highly Dispersed Gold Nanoparticles for Gas-Phase Selective Oxidation of Cyclohexanol to Cyclohexanone

MgCr2O4-Modified CuO/Cu2O for High-Temperature Thermochemical Energy Storage with High Redox Activity and Sintering Resistance

Metal oxides as high-temperature thermochemical energy storage systems with high energy density based on the gas-solid reaction are a critical demand for the future development of concentrated solar power plants. A copper-based system has high enthalpy change and low cost, but its serious sintering leads to poor reactivity. In this study, MgCr₂O₄ is decorated on the CuO/Cu₂O surface to effectively increase the sintering temperature and alleviate the sintering problem. The re-oxidation degree is increased from 46 to 99.9%, and the reaction time is shortened by 3.7 times. The thermochemical energy density of storage and release reach -818.23 and 812.90 kJ/kg, respectively. After 600 cycles, the oxidation activity remains 98.77%. Material characterization elucidates that nanosized MgCr₂O₄ is uniformly loaded on the surface of CuO/Cu₂O during the reversible reaction, and there is a strong interaction between metal oxides and prompter. Density functional theory (DFT) calculation further confirms that CuO/Cu₂O-MgCr₂O₄ has large binding energy and the formation energy of copper vacancy increases, which can effectively inhibit sintering. The modification mechanism of CuO/Cu₂O by MgCr₂O₄ is revealed, which can provide guidance for the reasonable design of thermochemical energy storage materials with sintering resistance and redox activity.

Biological investigation of a novel nanocomposite based on functionalized graphene oxide nanosheets with pectin, silk fibroin and zinc chromite nanoparticles

For biotechnology applications, a novel nanobiocomposite was synthesized based on modification of graphene oxide (GO) by extracted silk fibroin (SF), natural polymer pectin (Pec) and zinc chromite (ZnCr₂O₄) nanoparticles (NPs). The structure and properties of hybrid nanobiocomposite GO-Pec/SF/ZnCr₂O₄ such as thermal stability, less toxicity, biocompatibility, antibacterial, and biodegradable were proved by using field emission scanning electron microscope (FE-SEM), Fourier-transformed infrared (FT-IR), Energy dispersive X-ray spectroscopy (EDS), thermal gravimetric analysis (TGA), and X-Ray diffraction (XRD). According to the biological features of substances, the GO-Pec/SF/ZnCr₂O₄ nanobiocomposite shows perfect results in MTT (83.71 %) and Hemolysis (16.52 %) assays. accordingly, mentioned properties of this nanobiocomposite can be used as a scaffold for medical applications.

Synergy in Au-CuO Janus Structure for Catalytic Isopropanol Oxidative Dehydrogenation to Acetone

The controlled oxidation of alcohols to the corresponding ketones or aldehydes via selective cleavage of the β-C-H bond of alcohols under mild conditions still remains a significant challenge. Although the metal/oxide interface is highly active and selective, the interfacial sites fall far behind the demand, due to the large and thick support. Herein, we successfully develop a unique Au-CuO Janus structure (average particle size=3.8 nm) with an ultrathin CuO layer (0.5 nm thickness) via a bimetal in situ activation and separation strategy. The resulting Au-CuO interfacial sites prominently enhance isopropanol adsorption and decrease the energy barrier of β-C-H bond scission from 1.44 to 0.01 eV due to the strong affinity between the O atom of CuO and the H atom of isopropanol, compared with Au sites alone, thereby achieving ultrahigh acetone selectivity (99.3 %) over 1.1 wt % AuCu_0.75 /Al₂ O₃ at 100 °C and atmospheric pressure with 97.5 % isopropanol conversion. Furthermore, Au-CuO Janus structures supported on SiO₂ , TiO₂ or CeO₂ exhibit remarkable catalytic performance, and great promotion in activity and acetone selectivity is achieved as well for other reducible oxides derived from Fe, Co, Ni and Mn. This study should help to develop strategies for maximized interfacial site construction and structure optimization for efficient β-C-H bond activation.

The reaction mechanism of acetylene hydrochlorination on defective carbon supported ruthenium catalysts identified by DFT calculations and experimental approaches

The electron density of ruthenium ions in RuCl3/AC-D catalyst increases, which reduces the energy barrier of the main reaction and inhibits the side reactions.

Vapor-phase oxidation of cyclohexane over supported Fe-Mn catalysts: in situ DRIFTS studies

Alumina-supported Fe-Mn oxide catalysts were synthesized by the incipient wetness impregnation method. The catalysts were characterized using various characterization techniques such as surface area, XRD, H2-TPR, and Raman spectral analysis. The adsorption (Cy-H, CO2) and oxidation of cyclohexane (Cy-H) were conducted by considering the in situ DRIFTS studies. The iron-impregnated catalyst possessed a higher surface area than the manganese-impregnated catalyst. The manganese-oxides remained dispersed in the support and the iron oxides remained in the crystalline phase in the catalyst 20Fe50Mn50/Al2O3. The reduction temperature of the catalyst decreased due to the synergistic effects of the iron-manganese oxides. The catalyst 20Fe50Mn50/Al2O3 was the most active for the vapor-phase oxidation of cyclohexane at 220 °C and 1 atm pressure. The cyclohexanolate, phenolate, and unidentate carbonate species were observed during the study. The lattice oxygen of the catalyst activates the C-H bond of cyclohexane for the formation of reactive-cyclohexanol, further decomposed by dehydration and dehydrogenation.

A comprehensive and updated review of studies on the oxidation of cyclohexane to produce ketone-alcohol (KA) oil

Oxidation of cyclohexane is an essential chemical reaction for the industrial manufacture of cyclohexanol and cyclohexanone. These two compounds, together known as ketone–alcohol (KA) oil, are the main feedstock for nylon 6 and nylon 6,6 productions. Several types of catalysts and reaction conditions have been used for cyclohexane oxidation. This paper presents a thorough literature review of catalytic materials used for cyclohexane oxidation to produce KA oil using oxygen, air and other oxidizing agents as well as utilizing different solvents. This review covers research and development reported over the years 2014–2020. This review aims to comprehend the type of catalysts, solvents, oxidants and other reaction parameters used for the oxidation of cyclohexane. Three types of cyclohexane oxidation processes namely thermocatalytic, photocatalytic and microwave-assisted catalytic have been reported. The results of the review showed that metal and metal oxide loaded silica catalysts performed excellently and provided high selectivity of KA oil and cyclohexane conversion. The use of peroxides is not feasible due to their high price compared to air and oxygen. Gold nanoparticles supported on silica performed with high selectivity and good conversion. The use of hydrochloric acid as an additive was found very effective to enhance the photocatalytic oxidation of cyclohexane. Water on the catalyst surface enhanced the reactivity of the photocatalysts since it helps in the generation of hydroxyl radicals.

Self-assembly of a highly stable and active Co3O4/H-TiO2 bulk heterojunction with high-energy interfacial structures for low temperature CO catalytic oxidation

Self-assembly of a highly stable and active Co₃O₄/H-TiO₂ bulk heterojunction with high-energy interfacial structures was realized for low temperature CO catalytic oxidation.