Formation of sulphur compounds in hydrodenitrogenation of quinoline, 1,2,3,4-tetrahydroquinoline, pyridine, piperidine and 1-pent-4-enylamine on a nickel-tungsten catalyst in the presence of hydrogen sulphide
Hydrodenitrogenation (HDN) of quinoline and 1,2,3,4-tetrahydroquinoline on a sulphided nickel-tungsten catalyst in the presence of hydrogen and of its mixture with hydrogen sulphide has been studied in an autoclave at 350 °C. The results show that hydrogen sulphide exhibits rate-accelerating effect on HDN of the above compounds by formation of sulphur compounds. It was found that neutral portion of the reaction mixture contains octahydro-2H-1-benzothiopyran, octahydro-1H-2-benzothiopyran, octahydro-2-methylbenzo(b)thiophene and other sulphur compounds. The reaction scheme for HDN of quinoline that accounts for favourable effect of hydrogen sulphide is proposed. In the neutral portion of the reaction mixture from HDN of piperidine and 1-pent-4-enylamine in the presence of hydrogen sulphide further sulphur-containing compounds were identified.