Study On The Desulfurization Of Catalytic Cracking Diesel With Chemical Method

Diesel oil plays an important role in the various kinds of fuels in the 21st century.To protect the environment against SO_x,many countries recently have mandated a reduction in the sulfur of fuels and it has become an urgent task.Hydrogenation desulfurization system (HDS) is the traditional desulfurization technology which has been used widely.But it has high react condition,such as high temperature,high pressure and high cost of operation and maintenance.So,searching the economic and effective desulfurization system has been paid a great attention at home and abroad.Oxidation desulfurization of diesel fuel can be mostly conducted by using H₂O₂ as oxidizing agent and employing organic acid,heteropoly acid or inorganic solid acid as catalysts,which consumed large amount of H₂O₂.In this paper,two novel oxidation desulfurization systems were studied.KClO₃ and K₂Cr₂O₇ were respectively combined with hydrochloric acid for new KClO₃/HCl system and K₂Cr₂O₇/HCl system.Results indicated that the catalytic cracking diesel was well oxidized by both systems.The following are the two parts of the paper.1.KClO₃/HCl system for oxidation desulfurization(1) Oxidation desulfurization of model compounds in KClO₃/HCl system was investigated.The influence of oxidant amount,reaction temperature,reaction time,different pH and V(HCl):V(oil) were discussed.At the optimum conditions,the DBT removal rate was up to 99.89%.The oxidation product of the model compounds was also analyzed.(2) Based on the study of model compounds,the method on desulfurization from catalytic cracking diesel was investigated.The results indicated that the organic sulfur compounds in the catalytic cracking diesel can be removed effectively by KClO₃/HCl system. When n(KClO₃):n(S)=7:1,reaction temperature was 50℃,reaction time was 90min,the pH was 1,V(HCl):V(oil) was 1:1,the radio of the extractant and the diesel oil was 2:3,the sulfur removal rate was 92%.(3) Ultrasound was introduced to provide energy for the reaction.Under the condition of n(KClO₃):n(S)=7:1,reaction temperature was 40℃,reaction time was 60min,the pH was 1,V(HCl):V(oil)=1:1,the radio of the extractant and the diesel oil was 2:3,the sulfur removal rate was 92%.Because of the ultrasound,the reaction temperture was reduced and the reaction time was shortened.2.K₂Cr₂O₇/HCl system for oxidation desulfurization (1)Oxidation desulfurization of catalytic cracking diesel in K₂Cr₂O₇/HCl system was investigated.Under the condition of reaction temperature was 50℃,reaction time was 60min, n(K₂Cr₂O₇):n(S)=1:2,V(HCl):V(oil)=1:10,the pH was 4,the radio of the extractant and the diesel was 2:3,the sulfur removal rate was 91.8%.(2) Ultrasound was introduced to provide energy for the reaction.Under the condition of reaction temperature was 30℃,reaction time was 30min,n(K₂Cr₂O₇):n(S)=1:2,V(HCl): V(oil)=1:10,the pH was 2,the radio of the extractant and the diesel was 2:3,the sulfur removal rate was 91.8%.Because of the ultrasound,the reaction temperature and the reaction time were shortened.