Catalytic hydroprocessing of chlorobenzene–pyridine mixtures

The catalytic hydrotreatment of chlorobenzene–pyridine mixtures has been studied using a commercial Ni–Mo/ γ -Al 2 O 3 sulphided catalyst. Experimental runs were carried out in a batch reactor at constant temperature ( T =300 and 350°C) and hydrogen pressure ( P =5 and 50 bar). The reaction medium was hexadecane. The experimental results show that both the hydrodechlorination (HDCl) and the hydrodenitrogenation (HDN) processes were strongly inhibited when pyridine and chlorobenzene were hydrotreated in admixture. The formation of salts due to the reaction of nitrogen basic compounds (particularly piperidine which is a pyridine HDN intermediate) with hydrochloric acid (produced by HDCl of chlorobenzene) is hypothesised to be the reason for the reduction of the catalyst activity. Experimental results are modelled assuming a Langmuir–Hinselwood kinetic. The obtained results are of importance for the development of the HDCl process of chlorinated liquid wastes contaminated by nitrogen compounds.