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Direct Oxidation of Cyclohexane to Adipic Acid by a WFeCoO(OH) Catalyst: Role of Brønsted Acidity and Oxygen Vacancies
D. Vernekar, M. Dayyan, S. Ratha, C.V. Rode, M.ALI. Haider, T.S. Khan,
Published in American Chemical Society
2021
Volume: 11
   
Issue: 17
Pages: 10754 - 10766
Abstract
This work reports the catalytic activity of the trimetallic mixed-metal oxyhydroxide WFeCoO(OH) for the direct oxidation of cyclohexane to adipic acid (AA) without the use of concentrated HNO3. WFeCoO(OH) displayed a 40% conversion of cyclohexane and a 67% selectivity to AA under relatively milder conditions of temperature (90 °C) and pressure (1 atm). Experimental evidence confirmed the presence of acidic, basic, and redox sites on WFeCoO(OH). The detailed investigation revealed that doping W in the Co-FeO(OH) matrix increased the amount of surface lattice oxygen (OS-L) and caused a significant surge in acidity (5.1 mmol/g). The calculated deprotonation energy of WFeCoO(OH) was 1434 kJ/mol, and the trend in acidity was WCoO(OH) < WFeCoO(OH) < FeCoO(OH) ∼ CoO(OH). Energy calculations showed that WFeCoO(OH) had a high propensity to generate oxygen vacancies by the loss of either a water molecule or an oxygen atom (−132.2 or −140.9 kJ/mol, respectively). Basicity was generated due to the presence of conjugate pairs of the surface hydroxyl groups. The combined action of the trifunctional acidic, basic, and redox-active metal centers along with the oxygen vacancies was responsible for the enhanced catalytic performance. © 2021 American Chemical Society
About the journal
JournalData powered by TypesetACS Catalysis
PublisherData powered by TypesetAmerican Chemical Society
ISSN21555435