Inhibiting effects of basic nitrogen on deep hydrodesulfurization of diesel

The effect of nitrogen-containing compounds on the deep HDS of diesel feedstocks is a critical problem. Thus, a better understanding of nitrogen compounds and the intermediates formed during their decomposition, e.g., tetrahydroquinoline (THQ) that is formed during the HDN of quinoline, on HDS is required. There is also little literature on the effects of quinoline and tetrahydroquinoline (THQ) specifically on the HDS of dibenzothiophene and 4,6-dimethyldibenzothiophene. The inhibiting effects of THQ and quinoline on a commercial Co-Mo/γ-Al₂O₃ HDS catalyst were studied. Both forms of basic nitrogen inhibited the HDS of both polyaromatic sulfur compounds. However, THQ had a larger inhibiting effect in comparison to quinoline. The origin of this higher inhibiting effect was attributed to the former's marginally higher proton affinity.