Journal of Saudi Chemical Society (Sep 2023)
The catalytic activity of copper/nickel supported on mesoporous aluminum catalyst towards cyclohexene epoxidation in continuous reactor
Abstract
The intent of the study is to attain a high selectivity rate and stable interaction between metals in any heterogeneous catalyst. Cyclohexene is extremely valuable in industrial domains such as the synthesis of perfumes and nylons, and the mesoporous alumina was upstretched with a various ratio of bimetal copper (10%) and nickel (5%, 10%, 15%, and 20%) under wet impregnation procedures by the mesoporous aluminum catalyst. This impregnation of a metal and catalyst was used to assess the highest conversion and selectivity of cyclohexene to cyclohexanol. This catalytic nature was validated by analyzing the crystal structure and size using the X-ray diffraction technique. The functional group is identified using FT-IR (Fourier Transform Infrared Spectroscopy), while the surface area is assessed using BET (Brunauer-Emmet-Teller). HR-TEM (transmission electron microscopy) is used to validate the morphology of catalysts and their surface layers; HR-SEM (Scanning Electron Microscopy) is used to highlight and assess microparticles; and NH3TPD (Temperature-Programmed Desorption) is used to measure the overall acidity of the catalyst. The catalytic performance was proved by the yield achieved by varying parameters such as temperature, pressure, WHSV−1, reaction time, and solvents, which yielded over 98.5% in both cyclohexene conversion and selectivity. In the conversion of the product, H2O2 performs as an oxidant, and acetonitrile serves as a solvent at constant mild conditions of 90 °C and 20 bar pressure. Furthermore, even after seven successive runs with the Al2O3/Cu (10%)-Ni (15%) mixture, remarkable reusability was attained despite a minor decline in cyclohexanol selectivity. The effective impregnation of copper and nickel into supported mesoporous Al2O3 produced a long-lasting, stable hybrid nanostructure with excellent stability and no metal leaching. The current synthesis protocol's advantages and qualities include its efficiency, cost-effectiveness, ecological sustainability, and comfort of synthesis with readily available components.
