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Study On Preparation Of Niobium Modified NiMo/γ-Al2O3 Catalyst And Its Hydrodesulfurization Performance

Posted on:2020-03-03Degree:MasterType:Thesis
Country:ChinaCandidate:X W ZhuFull Text:PDF
GTID:2481306500985949Subject:Chemical Engineering
Abstract/Summary:PDF Full Text Request
With the gradual exhaustion of conventional crude oil and the increasing of heavy crude oiloutput,the sulfur content of crude oil in China increases year by year,which will pose new challenges to the cleanliness of vehicle diesel oil.The design and preparation of hydrodesulfurization catalysts with higher performance is the key to deal with this challenge.The key point is to understand the structure-activity relationship between the microstructure of active phase of transition metal sulfide and its deep hydrodesulfurization performance.In this paper,DBT is used as the model compound to investigate the effect of auxiliary agent of Nb2O5 in depth.By optimizing the content of auxiliary agent Nb2O5 and selecting the best ratio of auxiliary agent,the industrial catalyst is modified to provide technical support for the hydrodesulfurization reaction of straight run diesel.A series of catalysts with Nb2O5 additive were prepared by using DBT toluene solution as raw material.The effect of Nb2O5 additive on Ni/γ-Al2O3、Mo/γ-Al2O3、NiMo/γ-Al2O3catalysts and impregnation sequence on hydrodesulfurization were studied.The results show that the introduction of Nb2O5 promoter can improve the acid properties of NiMo/γ-Al2O3catalyst and improve its L acid.In addition,the introduction of Nb2O5 additive can significantly improve the vulcanization of Mo species of NiMo/γ-Al2O3 catalyst,improve the degree of vulcanization of active components,and increase the desulfurization rate.The DBT hydrodesulfurization performance of modified catalysts were evaluated under the condition of reaction pressure 2.0MPa,reaction temperature 260℃,volume air velocity 2h-1,and hydrogen to oil ratio 300:1.The introduction of Nb2O5 additive can improve the hydrodesulfurization effect of NiMo/γ-Al2O3catalysts.Secondly,NiMo/γ-Al2O3 catalysts with Nb2O5 auxiliary loading of 0.5wt%,1wt%,2wt%and 3wt%was prepared by equal volume impregnation method.The effect of different loading of Nb2O5 additives on the hydrodesulfurization activity of NiMo/γ-Al2O3 catalysts were investigated.Under the same condition,the results show that the reactivity of Nb2O5 adjuvant content,but it was higher than before the addition of additives.When the content of Nb2O5promoter is 0.5wt%,DBT has the highest hydrodesulfurization activity.Finally,straight-run diesel was used as raw material,and 0.5wt%Nb2O5auxiliary agent was used to modify its oxidation state and sulfide industrial catalysts.The analysis and characterization of the modified catalysts and the selective hydrodesulfurization activity evaluation were carried out.When the reaction pressure is 6.7MPa,the reaction is 375℃,the H2/oil ratio is 450,and the LHSV is 2.09h-1,the sulfur content of the oxidation catalyst and the sulfide modified catalyst can be reduced to less than 10ppm,and the sulfur content of the oxidation state modified catalyst can be reduced to 8.7ppm,which is in line with the nation VI standard.The sulfide modified catalyst can significantly improve the hexadecane value of the product oil after the reaction,which can better improve the properties of the product oil and provide the oretical basis and practical experience for industrial scale-up production.
Keywords/Search Tags:NiMoS, Nb2O5, catalysts, modification
PDF Full Text Request
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