Catalytic hydrodeoxygenation: III. Interactions between catalytic hydrodeoxygenation of m-cresol and hydrodenitrogenation of indole

Abstract

Simultaneous hydrodenitrogenation (HDN) and hydrodeoxygenation (HDO) is studied with indole/ m-cresol conversions over a sulfided CoMo HDS catalyst. The mutual inhibition of indole (and indoline) on HDO and of m-cresol on HDN is established. As with HDS/HDO reported in paper II, the HDN/HDO reactions appear to proceed on the same site. The relative reactivity of the indole and cresol, as well as an HDN intermediate, o-ethyl aniline, is m-cresol ⪢ o-ethyl aniline > indole (indoline). Under the conditions of our study ( P H 2 = 69 atm, T = 250–350 °C), the indole-indoline hydrogenation equilibrium is essentially achieved. The pure component conversion kinetics are adequately described by a two-site Longmuir-Hinshelwood form, the rate and binding constant values indicating correctly the relative reactivity and mutual inhibition magnitudes, thus confirming that simultaneous HDO and HDN proceed on the same surface sites. At the lower HDN temperatures, the intermediate o-ethyl aniline is converted to ethylbenzene, then ethylcyclohexane, while at or above 300 °C some ring hydrogenation to o-amino ethylcyclohexane precedes HDN. Hydrogenation, HDO, and HDN activities are completely recovered by 400 °C regeneration, in contrast to activity loss noted in paper II for simultaneous HDS/HDO.