CoO/CeOcomposites with high surface areas and ultrafine crystalline sizes for catalytic combustion of methane were firstly prepared by a new sol-gel method which combined ultrasonic impregnation treatment and calcinat...CoO/CeOcomposites with high surface areas and ultrafine crystalline sizes for catalytic combustion of methane were firstly prepared by a new sol-gel method which combined ultrasonic impregnation treatment and calcination in Natmosphere. The samples were characterized by various means such as nitrogen adsorption/desorption, X-ray diffraction(XRD), Htemperature-programmed reduction(H-TPR),X-ray photoelectron spectroscopy(XPS) and transmission electron microscopy(TEM). Results showed that the modified catalyst had the mesoporous structure, comparatively higher amount of surface oxygen and larger oxygen vacancies than others. As a result of the structure and surface composition merits, a high methane combustion conversion(50%) could be obtained at a low temperature of 262 °C for the modified CoO/CeOcomposites catalysts. The experimental results demonstrated that ultrasonic impregnation treatment combined with the Nthermal treatment prior to calcination in air had a promising application for preparation of CoO/CeOcomposites catalysts for low-temperature catalytic combustion of methane.展开更多
The one-step highly selective oxidation of cyclohexane into cyclohexanone and cyclohexanol as the essential intermediates of nylon-6 and nylon-66 is considerably challenging.Therefore,an efficient and low-cost catalys...The one-step highly selective oxidation of cyclohexane into cyclohexanone and cyclohexanol as the essential intermediates of nylon-6 and nylon-66 is considerably challenging.Therefore,an efficient and low-cost catalyst must be urgently developed to improve the efficiency of this process.In this study,a Co_(3)O_(4)–CeO2 composite oxide catalyst was successfully prepared through ultrasound-assisted co-precipitation.This catalyst exhibited a higher selectivity to KA-oil,which was benefited from the synergistic effects between Co^(3+))/Co^(2+))and Ce^(4+)/Ce^(3+)redox pairs,than bulk CeO2 and/or Co_(3)O_(4).Under the optimum reaction conditions,89.6%selectivity to KA-oil with a cyclohexane conversion of 5.8%was achieved over Co_(3)O_(4)–CeO2.Its catalytic performance remained unchanged after five runs.Using the synergistic effects between the redox pairs of different transition metals,this study provides a feasible strategy to design high-performance catalysts for the selective oxidation of alkanes.展开更多
文摘CoO/CeOcomposites with high surface areas and ultrafine crystalline sizes for catalytic combustion of methane were firstly prepared by a new sol-gel method which combined ultrasonic impregnation treatment and calcination in Natmosphere. The samples were characterized by various means such as nitrogen adsorption/desorption, X-ray diffraction(XRD), Htemperature-programmed reduction(H-TPR),X-ray photoelectron spectroscopy(XPS) and transmission electron microscopy(TEM). Results showed that the modified catalyst had the mesoporous structure, comparatively higher amount of surface oxygen and larger oxygen vacancies than others. As a result of the structure and surface composition merits, a high methane combustion conversion(50%) could be obtained at a low temperature of 262 °C for the modified CoO/CeOcomposites catalysts. The experimental results demonstrated that ultrasonic impregnation treatment combined with the Nthermal treatment prior to calcination in air had a promising application for preparation of CoO/CeOcomposites catalysts for low-temperature catalytic combustion of methane.
基金supported by Key Research and Development Program in Hunan Province(Grant No.2019GK2041)Hunan Provincial Natural Science Foundation of China(Grant No.2019JJ50579)+3 种基金Scientific Research Fund of Hunan Provincial Education Department(Grant Nos.18C0106 and 20B550)the fund of the Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education&Hubei Key Laboratory of Catalysis and Materials Science(Grant No.CHCL21004)National Training Program of Innovation and Entrepreneurship for Undergraduates(Grant No.S202010530022)and Hunan Key Laboratory of Environment Friendly Chemical Process Integrated Technology and Collaborative Innovation Center of New Chemical Technologies for Environmental Benignity and Efficient Resource Utilization.
文摘The one-step highly selective oxidation of cyclohexane into cyclohexanone and cyclohexanol as the essential intermediates of nylon-6 and nylon-66 is considerably challenging.Therefore,an efficient and low-cost catalyst must be urgently developed to improve the efficiency of this process.In this study,a Co_(3)O_(4)–CeO2 composite oxide catalyst was successfully prepared through ultrasound-assisted co-precipitation.This catalyst exhibited a higher selectivity to KA-oil,which was benefited from the synergistic effects between Co^(3+))/Co^(2+))and Ce^(4+)/Ce^(3+)redox pairs,than bulk CeO2 and/or Co_(3)O_(4).Under the optimum reaction conditions,89.6%selectivity to KA-oil with a cyclohexane conversion of 5.8%was achieved over Co_(3)O_(4)–CeO2.Its catalytic performance remained unchanged after five runs.Using the synergistic effects between the redox pairs of different transition metals,this study provides a feasible strategy to design high-performance catalysts for the selective oxidation of alkanes.
