Charge effects on quinoline hydrodenitrogenation catalyzed by Ni–Mo–S active sites-A theoretical study by DFT calculation

The charge distribution on Ni–Mo–S active sites can affect hydrodenitrogenation (HDN) activity. In this study, a series of model Ni–Mo–S were developed with various charge distributions. For comparison, the charge distribution effects on quinoline HDN were studied. The results show that a lack of electrons and extra protons can both lower the orbital eigenvalue of the Ni–Mo–S, leading to stronger adsorption of nitrogen-containing compounds and inhibition of ammonia desorption. Electron deficiency will improve the generation of active hydrogen on the active sites but inhibit hydrogen transfer to the nitrogen compounds; extra protons can provide H+ to the nitrogen compounds, which will flexibly transfer between the nitrogen compound and active sites, thus improving the cleavage of the C–N bond.