Research On Coal Tar Hydrodeoxygenation Process And Reactor Simulation

With the depletion of the world's petroleum resources,research on crude oil substitutes has attracted people's attention.As a by-product of coal pyrolysis,coal tar is valued by the industry for its potential value for processing gasoline and diesel.At present,although coal tar hydrogenation technology has been industrialized,However,the hydrotreating technology of coal tar refers to crude oil refining technology and lacks independent theoretical system.Coal tar has a high oxygen content unlike crude oil.These oxygen-containing compounds have a great influence on the stability of oil combustion and the service life of the engine.Therefore,it is particularly important for the removal of oxygen in coal tar.In this paper,240? low temperature coal tar was used as the raw material.Based on the Ni Mo/?-Al2O3 catalyst,the hydrodeoxygenation experiment was completed on a fixed bed reactor.The study first analyzed the effects of reaction conditions(temperature,pressure,space velocity)on the carbon number,hydrogen number,and oxygenate conversion process of monocyclic oxygenates in the product,and summarized the hydrodeoxygenation reaction of coal tar.Based on the experimental results,a three-phase reactor model was established for hydrodeoxygenation of oxygenates,hydrogenation of aromatic rings,and hydrocracking.The model parameters of each model were estimated and verified.Finally,the hydrodeoxygenation reactor used in the laboratory was simulated.The changes in pressure and concentration of reactants and products in the hydrodeoxygenation,hydrosaturation and hydrocracking reactions with the catalyst bed were studied respectively.Furthermore,the changes of the catalyst efficiency factors and the Sear modulus of the three reactions with the catalyst bed were analyzed.The study reached the following conclusions:(1)The study found that the three reactions of hydrogenation saturation,cracking,and deoxygenation not only occur simultaneously,but also affect each other.When the process conditions are changed to promote the deoxidation reaction in coal tar,the rate of the hydrogenation reaction and the hydrocracking reaction will also increase.By analyzing the sulfur and nitrogen content in the hydrogenation product,it can be known that the hydrodesulfurization rate is higher than the hydrodenitrogenation rate at high temperature and low space velocity.Under high pressure,the reaction rate is just the opposite.(2)Based on gproms software,the hydrodeoxygenation of oxygenates,the hydrogenation of aromatic rings and the kinetics of hydrocracking were established.The activation energies of the three reactions were obtained through nonlinear fitting:74092 J/mol,94147 J/mol,107897 J/mol,and the reaction order was 1.38,1.34,and 1.21,respectively.The accuracy verification results show that the model parameter errors are all less than 9%.The three reaction rate constants were solved and found that the hydrodeoxygenation rate>hydrosaturation rate>hydrocracking rate.It is found through simulation of hydrodeoxygenation reactor that high temperature,high pressure and low space velocity are favorable for hydrodeoxygenation reaction.The impact order is:temperature>pressure>airspeed.The catalyst efficiency factors of the three reactions increase with the increase of the catalyst bed.The efficiency factor of the catalyst for hydrodeoxygenation reaction is low,and the influence of internal diffusion on its reaction exists.The catalyst efficiency factors of the hydrosaturation reaction and the hydrocracking reaction are both about 1,and the effect of diffusion on the reaction can be ignored.