Formation of Nitrogen Compounds from Nitrogen-Containing Rings during Oxidative Regeneration of Spent Hydroprocessing Catalysts

Abstract

Commercial CoMo and NiMo catalysts in an oxidic and sulfided form and a γ-alumina were deposited with pyrrole, pyridine, and quinoline. The deposited catalysts and two spent hydroprocessing catalysts were pyrolyzed and oxidized under conditions typical of regeneration of hydroprocessing catalysts. The formation of NH 2 and HCN, as well as selected cases of N 2 O and NO, was monitored during the experiments. NH 2 and HCN were formed during pyrolysis of pyrrole-deposited catalysts whereas only NH 2 was formed during that of pyridine- and quinolinedeposited catalysts. For all deposited catalysts, both NH 2 and HCN were formed during temperature programmed oxidation in 2% O 2 . For spent catalysts, a small amount of N 2 O was formed in 2 and 4% O 2 . For pyrrole-deposited catalysts, large yields of N 2 O were formed in 4% O 2 . Under the same conditions, N 2 O yields for pyridine- and quinoline-deposited catalysts were very small