Boosting Creation of Oxygen Vacancies in Co-Co3O4 Homogeneous Hybrids for Aerobic Oxidation of Cyclohexane

• DOI: 10.1007/s10562-021-03638-0
• Publication Date: 2021-04-26T18:33:25Z
• Authors: Enxian Yuan; Meixia Zhou; Mingqing Gu; Panming Jian; Lin Xia; Jingran Xiao
• Keywords: 13. Climate action; 02 engineering and technology; 0204 chemical engineering; 0210 nano-technology; 7. Clean energy

Co-Co3O4 hybrids were synthesized by pyrolysis of Co2+/ZIF-67 precursors and employed into cyclohexane aerobic oxidation. Homogeneity degree of Co3O4 distribution in Co was affected by the cobalt loading. The homogeneity of Co-Co3O4 hybrids brought about the low crystallinity and declined reducibility of Co3O4, creation of abundant oxygen vacancies due to the existence of Co-Co3O4 interaction. As the cobalt loading increased the amount of surface oxygen vacancies presented the volcano shape and maximized at 65.3 wt%. The catalytic performance was positively correlated with surface oxygen vacancies and the highest conversion of 16.3% with 96.5% KA oil selectivity was obtained over 65Co-Co3O4/CN catalyst. Kinetic study revealed that the presence of abundant oxygen vacancies can effectively decrease the activation energy of cyclohexane oxidation via the promoted activation of O2. Additionally, water formed during cyclohexane oxidation was the main reason for the catalyst deactivation because of the preferred adsorption on the active sites.