The Basic Research On Removal Of Aromatics In Model Light Cyclic Oil

In recent years,the goverment continues to increase the intensity of air pollution control,which has imposed tight quality regulations upon vehicle fuels.Diesel fuel is considered to be a major contributor of such harmful pollutants especially nitrogen oxide?NO_x?and particulate matter?PM?.The most severe regulatory standards are being applied to diesel fuels.In the past,most of studies aimed to control sulfur content and nitrogen content,researchers have developed a series of catalysts and processes which used for deep desulfurization and denitrification.Nowadays,increasing attentions is being paid to remove aromatics especially polycyclic aromatics effectively.The“National Standard 19147–2016”stipulates:polycyclic aromatics content isn't allowed to exceed 7%which will decrease to 4%compared to“National?Emission Standard”,and cetane number will equal to 51.In conclusion,adsorption method is introduced to remove polycyclic aromatics of LCO in order to develop more efficient process for enhancing cetane number.These experiments are exploratory studies.In this paper,the removal of aromatics was studied by static adsorption method.Through a large number of experimental studies,Ni supported?–Al₂O₃ and Cu supported SiO₂ were considered to have the best adsorption efficiency in a verity of transfer metal supported adsorbents,which were prepared by wet impregnation method.The crystal structure,surface morphology,particle size and pore structure as well as surface area of the adsorbents were characterized by X–ray diffraction?XRD?,Brunner-Emmet-Teller measurements?BET?,scanning electron microscope?SEM?,Py–IR.The preparation factors and reaction conditions were investigated in order to explore the best adsorption conditions of above types of adsorbent.In addition to preparing,there were some basic researches for LCO to investigate aromatic types and contents,also which have influence on cetane number.The results show that the Ni supported?–Al₂O₃ can reach to the best monocyclic aromatics adsorption rate of 92.71%and polycyclic aromatics adsorption rate of 95.41%which the adsorbent prepared at precursor concentration of 0.2 mol/L,impregnated time of 4 h,ultrasonic time of 10 min and calcination temperature of 300?.The best adsorption conditions were as follows:adsorption temperature 10?,adsorption time 8h,adsorbent oil ratio 1:15.In these conditions,adsorbent has excellent regeneration performance that the best monocyclic aromatics adsorption capacity of 3.41 mg/g and the best polycyclic aromatics adsorption capacity of 5.71 mg/g.For Cu/SiO₂ adsorbent,the best preparation conditions were as follows:precursor concentration of 0.1 mol/L,impregnated time of 6 h,ultrasonic time of 30 min and calcination time of 5 h.The best adsorption conditions were same as above at which the adsorbent indicated the best aromatics activity and capacity.These basic experiments of LCO show that monocyclic aromatics are mainly concentrated on light fractions and have little effect on cetane number,while polycyclic aromatics,especially tricyclic aromatics,are concentrated on heavier fractions and have a great influence on cetane number.