Coal Liquefaction Processing Optimization And Aromatic Compounds Hydrogenation Study In Corresponding Unit

Base on the background of products selection and optimization of coal liquefaction process,this study focus on the processing optimization of coal indirect liquefaction and related products refinement catalysts development such as aromatics compounds hydrogenation.The main results and conclusions are as follows.1)The dissertation put forward a combined HTFT-LTFT synthesis with fuel and chemical as main products.Based on the combined HTFT-LTFT synthesis with 5 million tons fuel per year,the composition and ccontent of hydrocarbon groups were systematically analyszed under different combined ratio of HTFT and LTFT synthesis and the content of alpha olefins under two-thirds ratio was 315 thousand tons.2)The dissertation proposed that ethylene oligomerizaiton process,the process of alpha olefins separation and synthetic lubricant that were the key technologies for the combined HTFT-LTFT synthesis.On the basis of simulation parameters of ethylene oligomerization,the technique-economics analysis was conducted to calculate process cost,working fund,internal rate of return and dynamic payback period.The economy of the combined HTFT-LTFT synthesis was compared with the coupling process of HTFT and LTFT from Sasol.The results showed that the suggested downstream processing of olefins was the economically viable for the combined HTFT-LTFT synthesis.3)According to the composition characteristics of coal direct liquefaction products and choosing benzene as a target reactant and thiophene as a model compound,with the metal nitride catalysts as the research subject,the dissertation analyzed and evaluated the structure,electronic properties and sulfur resistance by the combined method of theoretical calculation and experiments.The experimental results revealed the benzene hydrogenation performance of Mo2N fell to 1 ?mol·gcat-1·s-from 4 ?mol-gct-1·s-1 in the presence of thiophene under 250 ? and 3 MPa.XPS results showed that the surface of catalyst was sulfided.S elements that was strongly adsorbed on the catalyst surface has occupied the active sites,which lead to the decline the hydrogenation performance.Based on the first principles,the structure of Mo2N was optimized by Material Studio theoretical calculation software.The results implied that Mo2N displayed metal properties.Benzene was physcial adsorption on Mo2N(10 0)with-0.062 eV adsorption energy and 3.25 A of C-Mo minimum bond length,while,thiophene was parallelly adsorbed on Mo2N(1 0 0).4-hcp was the active site for hydrogenation desulfurization(HDS)and the rupture of conjugated Pi bond of thiophene was the rate-determining step for HDS.4)Based on the design principles of sulfur resistant catalysts,Ni2Mo3N was designed and prepared through adding the second active metal to Mo2N and the hydrogenation performance and sulfur resistance of Ni2Mo3N was analyzed.The evaluation results indicated Ni2Mo3N converted 19.5 ?mol benzene per unit time and catalyst in the absence of thiophene under 250 ? and 3 MPa and the;catalytic activity exceeded that of Pt/Al2O3.Under the same reaction conditions,the catalytic activity of Ni2Mo3N dropped to 4 ?mol·gcat-1·s-1 in the presence of thiophene.XPS results hinted the surface of Ni2Mo3N was sulfided.Thus,adding the second active metal promoted the hydrogenation performance and weakened the strong chemical adsorption between benzene and catalyst surface.The calculation results showed that Ni2Mo3N also displayed metal properites.The addition of Ni changed the form of Mo in the alloy through tranferring electrons from the d orbitals of Ni to Mo,whick was beneficial for the hydrogenation reaction,in terms of Fermi level and d hole.5)Based on the design principles of sulfur resistant catalysts,K promoted Ni2Mo3N was designed and synthesized through adding alkali additives and the hydrogenation performance and sulfur resistance of K promoted Ni2Mo3N was evaluated.The results manifested the adding of K reduced the crystallite size of Ni2Mo3N and Ni.The initial activity lower to 18 ?mol·gcat-1·S-1 from 22?mol·gcat-1·s-1 in the presence of thiophene under 250 ? and 3 MPa,however,the activity of K promoted Ni2Mo3N depressed to 6 ?mol·gcat-1·s-1 after 13 hrs.So,a lower crystallite size of Ni2Mo3N and Ni enhanced the hydrogenation activity of benzene and initial resistance for thiophene.The adding of K weakened the chemical adsorption capacity between thiophene and active metal.6)Based on the design priciples of sulfur resistant catlysts and preparation of nano material,bimetallic nitride catalyst was designed from the perspective of reducing the crystallite size.The dissertation analyzed the reactivity of benzene hydrogenation and sulfur resistance.XRD results showed the adding of P123 minished the crystallite size of Ni2Mo3N.The experimental results uncovered the catalytic activity was 22.5 ?mol-gcat-1·S-1 under 250 ? and 3 MPa in the absence of thiophene.When the reaction temperature was increased to 360 ?,the catalytic activity of benzene hydrogenation lowered by 2.7 ?mol·gcat-1·S-1.In the presence of thiophene,the initial activity of benzene hydrogenation was 16?mol·gcat-1·s-1 and then dropped to and kept 9.6 ?mol·gcat-1·s-1 after 3 hrs under 250 °C and 3 MPa,nevertheless,the acitivity maintained 17.5 ?mol·gcat-1·s-1 in 8 hrs after raising temperature to 360 ?.Herein,declining the crystallite size and raising reaction temperature seemed to enhance the sulfur resistance capacity and maintaining stable activity.7)Supported Ni2Mo3N possessed high specific surface and good dispersibility and converted 34 ?mol benzene per unit time and catalyst,moreover,the acitivty was stable.In the continuous flow reaction device,Ni2Mo3N/y-Al2O3 realized the hydrogenation of benzene derivatives from coal liquefaction under 300 ? and 3 MPa.