Toluene oxidation process and proper mechanism over Co3O4 nanotubes: Investigation through in-situ DRIFTS combined with PTR-TOF-MS and quasi in-situ XPS
Series of Co3O4 nanotubes and nanoparticles were synthesized via solvothermal method without template. In situ DRIFTS combined with PTR-TOF-MS, quasi in-situ XPS and UV–vis-DRS were introduced to learn the process of toluene oxidation, confirmed that the reaction mechanism over catalyst followed the...
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| Published in: | Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 397; p. 125375 |
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| Main Authors: | , , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Elsevier B.V
01-10-2020
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Series of Co3O4 nanotubes and nanoparticles were synthesized via solvothermal method without template. In situ DRIFTS combined with PTR-TOF-MS, quasi in-situ XPS and UV–vis-DRS were introduced to learn the process of toluene oxidation, confirmed that the reaction mechanism over catalyst followed the Mars-van Krevelen mechanism and surface lattice oxygen played an important role in deeper oxidation toluene. In addition, ring opened by-product species were detected by PTR-TOF-MS, while these species were not identified by in situ DRIFTS.
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•Co3O4 nanotubes and nanoparticle were synthesized via solvothermal method without template.•Co3O4 nanotubes exhibited high catalytic efficiency for toluene oxidation.•The role of surface lattice oxygen and gas phase oxygen were investigated and illustrated in detail.•Toluene oxidation process were investigated by combination of in-situ DRIFTS, PTR-TOF-MS, quasi in-situ XPS, UV–vis-DRS.
Improving catalytic efficiency is a yet still challenge in thermal catalytic oxidation. One of the key issues is to understand its catalytic oxidation mechanism. Here, a series of Co3O4 samples were prepared by solvothermal method. The characterization records showed that nanotubular Co3O4-NTs-2 for its rough surface, low temperature reducibility, abundance of Co3+ ions and surface adsorption oxygen species, thus exhibited high efficiency (T90 = 240℃, Ea = 67.42 kJ/mol) in catalytic oxidation of toluene. In-situ DRIFTS combined PTR-TOF-MS were applied to investigate the reaction process of toluene oxidation. These results revealed that the catalytic oxidation of toluene followed the listed way: toluene → benzyl alcohol → benzaldehyde → benzoate → benzene → phenol → benzoquinone → maleic anhydride and other ring opening by-products like ethanol, acetaldehyde, acetic acid, acetone etc., then ultimately mineralized to CO2 and H2O. Furthermore, the results of quasi in-situ XPS in C7H8/N2, toluene conversion in O2-free evaluation and UV–vis-DRS analysis further confirmed that surface lattice oxygen played an important role in toluene oxidation, and gas-phase oxygen facilitated the reaction. The combination of a series of instruments provided a promising means for further understanding the oxidation mechanism of toluene. |
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| ISSN: | 1385-8947 1873-3212 |
| DOI: | 10.1016/j.cej.2020.125375 |