Effect Of Fraction Composition On Hydrodenitrogenation Of Coker Gas Oil

Nitrides in coker gas oil have an adverse impact on the catalysts and product quality during processing,and nitrides can inhibit the hydrodesulfurization reaction.Therefore,hydrodenitrification is the key to the hydrotreating of coker gas oil.At present,the research on hydrodenitrification mainly focuses on the preparation of catalysts and the mechanism of hydrodenitrification,but the research on the effects of different compounds on hydrodenitrification is limited.This paper studies the adsorption behavior of nitrides,the hydrodenitrification behavior of typical nitrides and actual oil products,to discuss the effects of different compounds on the hydrodenitrification performance of nitrides.In order to provide a basic theoretical basis for optimizing hydrotreating process conditions and developing new high-efficiency hydrodenitrification catalysts,this paper further explores the reasons why nitrides are difficult to remove.Firstly,the competitive adsorption behavior of quinoline,indole,dibenzothiophene,naphthalene and phenanthrene was studied on Ni Mo/Al₂O₃ catalyst.The equilibrium adsorption capacities of quinoline,indole,dibenzothiophene,naphthalene and phenanthrene were determined,and the adsorption selectivity of different compounds was described by fitting Langmuir and Freundlich isothermal adsorption curves.The order of adsorption selectivity is:quinolone>indole>dibenzothiophene>naphthalene>phenanthrene.Quinoline showed the strongest competitive adsorption when the competitive adsorption behavior of different compounds was investigated.The effects of aromatics and sulfur nitrogen compounds on the conversion and path selectivity of nitrides hydrodenitrification were studied.The experimental results show that dibenzothiophene can promote the hydrodenitrification at low concentration,mainly promoting the selectivity of the hydrogenolysis path of nitrides.However,dibenzothiophene will inhibit hydrodenitrification at high concentration,because H₂S can be adsorbed on the active site and inhibit the progress of hydrodenitrification.Phenanthrene can inhibit the hydrodenitrification by inhibiting the selectivity of the hydrogenation saturation path of nitrides,but its inhibition is relatively weak.The inhibitory effect of quinoline on indole is obvious,mainly because quinoline and its hydrogenation products inhibit the hydrodenitrification of indole.Moreover,indole does not have obvious self inhibition.Finally,the effects of different fractions on the hydrodenitrification of coker gas oil were investigated by changing the contents of aromatics and sulfur and nitrogen compounds in the actual oil.The results show that the introduction of dibenzothiophene can improve the selectivity of basic nitrides hydrodenitrification.Phenanthrene mainly inhibited the selectivity of hydrodenitrification of non-basic nitrides.The reduction of basic nitrides can promote the removal of nitrides in coker gas oil,especially promoting the removal of non-basic nitrides.Both the adsorption study and the study on the hydrodenitrification behavior of typical nitrides and coker gas oil show that basic nitrides have a strong inhibitory effect on non-basic nitrides.When the content of basic nitrides decreases,the removal of non-basic nitrides becomes easier.Therefore,in order to achieve deep denitrification,the removal of basic nitrides is of vital importance.