The Research On Synthesis And Properties Of Diesel Blending Component Via 1-Hexene Prins Reaction

In the plateau areas,the diesel engine would arise some bad phenomenons like power decline,soot formation and reduced the life of engine because of the low oxygen desity.One of the ways to solve these problems is that,the oxygen-containing fuels could be added into the diesel according to certain proportion which could improve the oxygen content of diesel itself.In this paper,the properties like boiling point,oxygen content,pour point and the structure of the reaction products via ethylene,propylene,butane,pentene,hexene,heptene and formaldehyde were simulated by Chemoffice software.Select the reaction products which boiling point at the range of diesel distillate,oxygen content is moderate,low pour point and the branch is the straight chain.Considered the different factors,the products from1-hexene and formaldehyde Prins reaction was selected as the oxygen-containing diesel blending component.A new type of oxygen-containing diesel blending component with high density and calorific value was designed and synthesized via Prins reaction.And the reaction raw materials select 1-hexene and formaldehyde,the catalyst select macroporous acid resin and the reaction reactor select slurry reactor.The reaction conditions such as molar ratio reaction temperature,reaction time and reaction pressure were investigated,and the products were characterized by gas chromatography,mass spectrometry and nuclear magnetic resonance spectroscopy.The conversion of 1-hexene and the yield of the diesel blending components were investigated by single factor method,and the optimum reaction conditions were as follow,the molar ratio of 1-hexene and paraformaldehyde was 1:2.5,the reaction temperature was 105?,the reaction time was 6h and the initial reaction pressure was 1.5MPa.The yield of diesel blending components could reach 74.01%and the 1-hexene conversion rate could achieve 77.70%.The product 4-butyl-1,3-dioxane could be isolated by column chromatography and distillation,and the concentration of the product could reach 94.37%and 91.02%.The structure and content of all by-products were determined by mass spectrometry and gas chromatography.According to the structure and content distribution of the different products,the possible reaction mechanism was proposed.The properties of the products via 1-hexene Prins reaction like density,volume calorific value,cetane number,flash point,cold filter point,freezing point,distillation and a series of physical and chemical indicators of diesel were measured.The experimental results were showed that,the density of the products could reach 940kg/m³,the calorific value could reach32.52MJ/m³,the oxygen content could reach 23.54%,and the low-temperature performance such as the freezing point could reach-60?,cold filter point could reach-40?.When mixed with-35#automotive diesel,its physical and chemical indicators were better than-35#automotive diesel.Finally,this paper builded the kinetic model of 1-hexene and paraformaldehyde through designed the dynamic process.The experimental results were showed that the kinetic model of Prins reaction of 1-hexene and formaldehyde under the premise of eliminating the influence of internal and external diffusion factors is r=k₁C_A^1.1C_B^2.49 and paraformaldehyde was 3.59.The reaction activation energy was 135.03kJ/mol,and the pre-exponential factor was 3.29×10¹⁵.