期刊
FUEL
卷 288, 期 -, 页码 -出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.fuel.2020.119700
关键词
Toluene oxidation; AMn(2)O(4); Cation substitution; Oxygen activation
资金
- National Natural Science Foundation of China [21978314]
- Applied Basic Research Project of Shanxi Province [201901D111003]
Through substituting A(2+) and Mn3+, the study investigated the impact of the structure of AMn(2)O(4) spinel catalysts on toluene oxidation. The results showed that the catalytic activity is influenced by the substitution of A-site metal, enhancing low-temperature reducibility and chemisorption oxygen activity. The incorporation of A-site metal can improve the ability of the catalyst to activate molecular state oxygen, thus enhancing catalytic activity.
To investigate the underlying mechanism of the tetrahedral A(2+) cations and the octahedral Mn3+ cations in AMn(2)O(4) spinel catalysts for toluene oxidation, a series of structure-controlled AMn(2)O(4) spinel catalysts were prepared through substituting A(2+) and Mn3+ with Cu2+, Ni2+, Zn2+, and Fe3+, respectively. The evaluation results demonstrated that the catalytic activities arrange in the sequence of CuMn2O4 > NiMn2O4 > ZnMn2O4 > CuFe2O4, and the temperature required for 90% conversion of toluene is 205 degrees C for the CuMn2O4 catalyst. The physical properties of these samples were well characterized by XRD, TEM, N-2 adsorption-desorption isotherms. The influences of crystal type, micro structure and specific surface area were successfully eliminated by using KIT-6 as the hard template method. The influence mechanism of A-site metal was further explored by analyzing the results of XPS, H-2-TPR and O-2-TPD. Results showed that the catalytic activity of the samples was highly affected by the substitution of highly electronegative A-site metal due to the enhancement of low-temperature reducibility and chemisorption oxygen activity. In particular, it was found that the incorporation of A-site metal can improve the ability of the catalyst to activate molecular state O-2(-) to O-, which was highly related to the catalytic activity of the catalyst. The results hold guidance for the design of manganese spinel catalysts on the removal of VOCs.
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