Study Of Kinetic Model For Light Naphtha Hydroisomerization Reaction

With the increasingly stringent environmental protection regulations,the domestic automobile gasoline standard is constantly being upgraded,and the demand for high-quality clean gasoline blending components is increasing.The light paraffin hydroisomerized oils have the characteristics of low sulfur,low aromatics and olefins,and high octane,which is a very ideal choice.Therefore,building the kinetic model of the hydroisomerization reaction of light paraffins has important practical significance.Selecting HBeta molecular sieve and chloroplatinic acid as the main raw materials,the Pt/HBeta lighter alkane?C₅/C₆?isomerization catalyst was prepared by equal volume impregnation and characterized by some analysis methods.The results show that the prepared Pt/HBeta catalyst has a large specific surface area and pore volume,and the main pores are mainly micropores with some mesopores;acid strength is dominated by weak acid sites,and there are some strong acid sites.At the same time,it has B acid and L acid,B acid accounts for relatively large L acid,and the catalyst has good activity stability when evaluated by different raw materials.Using n-pentane and n-hexane as raw materials,the effects of reaction conditions such as reaction temperature,reaction pressure,WHSV,and hydrogen-oil volume ratio on the isomerization reaction were investigated.Based on these experients,n-pentane and n-hexane isomerization reaction kinetic models were established.The results showed that the isomerization of n-pentane was in accordance with a pseudo first-order kinetics model and the activation energies of reaction were E_a=156.37 KJ·mol^-1 and pre-exponential factor A=1.3710×10¹⁵ h^-1.In the range of 240? to 260?,the isomerization of n-hexane conformed to a pseudo first-order kinetics model and the activation energy of the reaction was E_a=139.06 KJ·mol^-1 and A=7.3814×10¹³ h^-1.When the reaction temperature was greater than 260?,the pseudo first-order kinetic model is not suitable.After correction,the reaction order at 270? is 1.3,and the reaction order at 280? is 1.7.At the same time,a series of n-hexane kinetic model was established,and the first step activation energy was E_a=167.80KJ·mol^-1,A=7.2130×10¹⁶ h^-1,and the second step activation energy was E_a=118.34 KJ·mol^-1.A=1.3053×10¹¹ h^-1.The effects of the ratio of n-hexane and n-pentane in the raw materials and the reaction conditions on the isomerization reaction were investigated.The results show that increasing the proportion of n-C₅/n-C₆ is beneficial to increase the isomerization rate of n-alkanes.The reaction conditions have the following influence order on the isomerization reaction:reaction temperature>weight hourly space velocity>reaction pressure.The raw materials includes pentane tower oil,pentane tower bottom oil and reformed raffinate oil.The 7 characteristic parameters of raw oils and 4 reaction conditions were used as input variables,and the PIN index and RON of the product were used as output variables.A three-layer BP neural network with a network structure of 11-11-2 has been established.The average relative error predicted by the established BP neural network model does not exceed 5%.The forecasting effect is good,but the expansion ability of this model needs further improvement.