DFT and experimental study on denitration mechanism over VPO/TiO2 catalyst
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A titanium dioxide supported VPO(VPO/TiO2) catalyst for NH3-SCR de-NOx was prepared. The NH3-SCR catalytic activity of VPO/TiO2 was tested and a corresponding mechanism was investigated by Density Functional Theory and in situ FTIR spectra. The results showed that the catalytic activity of VPO/TiO2 was the highest when the molar ratio of P to V was 1/5, weight percentage of active ingredient was 10 wt.% and calcination temperature was 400 °C. The de-NOx efficiency of 0.1VP(1/5)O/TiO2 calcined at 400 °C was above 98% at temperature range from 180 to 400 °C. The V2P2O15H12 cluster was constructed and the adsorption of NO and NH3 on the active site of VPO/TiO2 was investigated by density functional theory (DFT). The simulation results showed that NO could be chemisorbed on the O2 and O3 site of the V2P2O15H12 cluster, and the corresponding adsorption energy was − 74.95 kJ·mol−1 and − 47.30 kJ·mol−1 respectively. The adsorption energy of NH3 adsorption on O1, O2 and O3 site is − 95.88 kJ·mol−1, − 230.80 kJ·mol−1 and − 78.45 kJ·mol−1. Moreover, the electric charge transformation of H on O2 site is 0.589e, which is higher than that on O1 and O3 site. Accordingly, the NH3-SCR de-NOx reaction would occur more easily on the O2 site than on the O1 and O3 site. The simulated results and the in situ FTIR spectra showed that the reduction of NO by NH3 over VPO/TiO2 followed the E–R mechanism and L–H mechanism.
KeywordsNOx VPO/TiO2 SCR DFT Mechanism
This work was financially supported by the Major national R & D projects of China (2017YFB0601805) and National Natural Science Foundation of China (51674002).
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Conflict of interest
The authors declare that they have no conflict of interest.
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