Study Of Hydrodesulfurization Reaction Mechanism For Benzothiophene On Surface Of Ni₂P/TiO₂

With the increasing demand of petroleum,heavy oil has become one of the most important energy sources in the world.However,the viscosity of heavy oil is so high that it is difficult to extract,collect and process,and the environmental pollution is very serious during the processing of crude oil.Therefore,it is necessary to reduce the viscosity of heavy oil and reduce the sulfur content in it.Hydrodesulfurization?HDS?reaction is an important step in pyrolysis reaction,which is of great significance for viscosity reduction and desulfurization.In this paper,by using the Dmol³ module of Materials Studio?MS?computing simulation software,the sorption sites and hydrodesulfurization reaction of benzothiophene on Ni₂P and Ni₂P/TiO₂ surface are studied,the results showed that the most sTable sorption site of benzothiophene on Ni₂P and Ni₂P/TiO₂ surface is Ni-hcp,but the adsorption energy on Ni₂P/TiO₂ surface is larger,activation energy is lower,which indicating that the TiO₂ can not only strengthen the adsorption of benzothiophene on Ni₂P?001?surface,but also promote the hydrodesulfurization reaction.The simulation results of hydrodesulfurization reaction path show that indirect desulfurization of benzthiophene is more advantageous than direct desulfurization.The most likely route for indirect desulfurization is BT-DHBT-C8H9S2-PET-EB,and the most likely route for direct desulfurization is BT-C8H7S2-CMT-ST-EB.The experimental study on hydrodesulfurization of benzothiophene was carried out by self-made Ni₂P and Ni₂P/TiO₂ catalyst,the characterization of catalyst and the effects of reaction conditions on hydrodesulfurization are obtained.The results showed that the diffraction peak of Ni₂P/TiO₂ catalyst is lower than Ni₂P catalyst,and the specific surface area,pore volume,pore diameter are lower than TiO₂,indicating that Ni₂P has been effectively dispersed on the surface of TiO₂;The efficiency on hydrodesulfurization of benzothiophene increased with the increase of reaction temperature when the reaction temperature was below300,and it remained unchanged when the temperature was higher than 300,and the effect of reaction pressure on hydrodesulfurization efficiency of benzothiophene is very small;Meanwhile,the presence of ethylbenzene,phenyl mercaptan and thiophenol is detected in the liquid products,which verified the rationality of simulation reaction path.