Studies On Hydro-upgrading And Reaction Kinetics Of FCC Heavy Cycle Oil

The content of polycyclic aromatic hydrocarbons in heavy cycle oil?HCO?is high,so cracking performance is poor,and utilization rate is low.Therefore,this topic proposed heavy cycle oil hydrogenation to saturate part of the aromatic rings to naphthenic rings,so as to improve HCO H/C ratio,then loop back to the catalytic cracking unit for cracking.This paper investigated the regularity of HCO hydrogenation reaction to summarize the HCO hydrogenation depth control method and hydrocarbon structure change rules.Finally,a lumped dynamic model was established and calculated,so as to provide theoretical guidance for subsequent processing.First of all,representative polycyclic aromatic hydrocarbons of HCO—naphthalene,phenanthrene,pyrene were selected as the research objects to examine the performance of catalysts and reaction rules of exploration.Four different catalysts hydrogenation reaction results show that Ni and W are introduced in the catalysts or increasing supporters acidity can improve the activity of hydrogenation saturation effectively,but too much acid will aggravate cracking and isomerization reaction,and the larger the bore diameter,the more conducive to macromolecular aromatics adsorption and reaction.It is found that there is competitive adsorption between different aromatics in the reaction process.When two kinds of catalysts are used to be piecewise combination loaded,if loading catalysts in order?Highly hydrogenation active catalyst in the former,highly middle ring selectivity catalyst in the back?,it will be more advantageous to the saturation of different structures polycyclic aromatics,and it can reduce the cracking reaction;if in reverse order,it will be not conducive to the conversion of macromolecular aromatic hydrocarbons,and easy to cause excessive hydrogenation cracking reaction of small molecule aromatics.Hydrogenation reaction laws of naphthalene,phenanthrene,pyrene under different reaction conditions show that the influence of temperature on hydrogenation has a thermodynamic equilibrium area,the influence of pressure on ring cracking reaction is less,large volume space velocity is good for aromatics saturation,and the hydrogen oil ratio has less effect on the depth of hydrogenation.The middle rings of polycyclic aromatic hydrocarbons hydrogenation are more primary,and their hydrogenation are faster than the end rings,but subsequent hydrogenation process of rim rings are more likely to happen.YH-HCO was hydrogenated under the reaction conditions—reaction temperature340³90?,reaction pressure 6¹2 MPa,volume space velocity 1.0².0 h^-1,hydrogen oil ratio 400:1¹000:1 to investigate the influence of the reaction conditions on the depth of hydrogenation saturation and the hydrocarbon molecular structures.The study shows that saturation and ring opening reaction rate increase with pressure increasing,but a greater effect on saturated reaction.With the improving of reaction temperature,the saturation reaction has the best temperature,ring opening reaction rate increases continually.With the volume space velocity increasing,the rate of aromatics saturation and ring-opening cracking reaction are reduced,but there is a smaller effect on saturated reaction.The hydrogen oil ratio has less effect on the depth of hydrogenation,but it can strengthen the inhibition of ring cracking.Therefore,depending on the target product people can adjust the process parameters to achieve different effects of hydrogenation.The analysis of different hydrogenation depth HCO compositions and molecule structures show that there is a turning point when hydrogenated HCO density is reduced to 0.9424g/cm³.Before turning point,it mainly occurs polycyclic aromatics saturated to generate ring alkyl aromatics.When more than the turning point,naphthenic structures cracking reaction gradually comes to be dominated.By comparing the physical and chemical properties of YH-HCO and JN-HCO under different reaction depth,it can be found that the HCO which has more tetracyclic aromatics hydrogenation depth is more shallow than the HCO which has more tricyclic aromatics in the same reaction conditions,and with the hydrogenation degree deepening,the density of the HCO which has more tetracyclic aromatics decreases faster,but it is always higher than that of the HCO which has more tricyclic aromatics,thus to get the same depth of hydrogenation,the former need more harsh reaction condition,such as increasing pressure,appropriately raising the temperature or reducing the volume space velocity.According to characteristics of HCO hydrogenation de-aromatic reaction,this paper used an average molecular structure of hydrogenation HCO as the foundation to establish three lumped dynamic model of aromatic carbon,naphthenic carbon and alkyl carbon,and figured out the kinetic parameters.By comparing calculation value and experimental value,the dynamic model was proved to be reliable,but the model only applied to the HCO which has more tetracyclic aromatics.The calculation results of kinetic parameters show that the reaction rate of aromatic ring hydrogenation saturation>the reaction rate of naphthenic ring opening,and the promoting effect of reaction temperature on the reaction rate of ring opening is greater than that of aromatic ring saturation.By comparing with LCO hydrogenation kinetic parameters,it can be found that the aromatics in HCO are much more difficult to be hydrogenated than the aromatic hydrocarbons in LCO,but the naphthenic rings produced by aromatics hydrogenation are more prone to cracking.