A comprehensive study of indole catalytic hydrodenitrogenation under
hydrothermal conditions
Abstract
This article focuses on the catalytic hydrodenitrogenation (HDN)
mechanism of indole under hydrothermal conditions. Both gaseous hydrogen
and liquid hydrogen donor formic acid (FA) can improve indole conversion
and total yield of denitrogenated products. Ru/C showed the highest
activity among the catalysts for indole conversion in all temperature
conditions with the existence of H2 and 91.17 % indole was converted at
400 °C and 60 min. Based on reaction kinetic experiments, a kinetic
model was developed to describe the hydrothermal HDN reaction of indole
over the home-made Ni80Ru20/γ-Al2O3 catalyst, which clearly captured all
data trends and fitted the temporal variation of all major liquid
products. High activation energy for formation of O-containing substance
o-cresol from both mathematical fitting and density functional theory
(DFT) calculation indicated a rare occurrence of reaction between
pyrrole ring-opening product methyl aniline and H2O, consistent with
experimental observation that only a trace of o-cresol was detected.