Improvement Of FCC Middle Gasoline Hydrogenation On Supported Ni₂P Catalysts

The noble metal catalysts in catalytic reforming and isomerization process are expensive,and sulfur,nitrogen,chlorine poisons noble metal catalysts in catalytic converters.Meanwhile,the acidity of traditional Co?Ni?–Mo/Al₂O₃ hydrotreating catalysts is furnished by continuously adding chlorine,thus leading to corrosion.In this review we will focus on developing Ni₂P/?-Al₂O₃/SAPO-11 catalysts with high dispersion to study the performance of nickel phosphides for the hydroisomerization of n-heptane.After that,the FCC gasoline was cut by boiling distillation to select suitable FCC middle naphtha.It is accordingly inferred that the SAPO-11 supported Ni₂P catalysts may exhibit good performance for hydrodesulfurization?HDS?,and also show better performance for isomerization,aromatization of FCC middle naphtha,which could resume or improve octane value and decrease the content of olefin.The dehydrogenation performance of Ni₂P/Al₂O₃ was studied using cyclohexane as a model compound.The results showed that dehydrogenation of cyclohexane was the main reaction,and the conversion of cyclohexane was 99%,which meant almost no side reactions occured.The isomerization of SAPO-11 supported Ni₂P was studied using n-heptane as a model compound.When the Ni₂P loading is 4%,and the content of SAPO-11 was 30%in?-Al₂O₃/SAPO-11,there was a synergism between the Ni sites and the medium strength acid site.The isomerization selectivity of the catalyst was the best.Compared with the Pt-based catalyst,SAPO-11 supported Ni₂P had quite considerable isomerization selectivity,however,the isomerization activity and aromatization selectivity were relatively lower.For the FCC gasoline olefins mainly concentrated in the light cracked naphtha?LCN?,while sulfur and aromatic compounds in the heavy cracked naphtha?HCN?.It can minimize octane number loss in the process of hydrodesulfurization of FCC gasoline after splitting.The sulfur of LCN fraction could be removed by application of a sweetening process or pre-hydrogenation reaction.HCN were treated with deep hydrodesulfurization process.The medium fraction?MCN?had intermediate sulfur impurities and olefins,there were no processes combining this possibility of catalytic HDS with to minimize octane loss.Therefore,a kind of FCC gasoline hydro-upgrading process was designed.This process was to achieve deep desulfurization and the goal of reducing olefins to produce Stage V gasoline.The catalytic activity of suitable catalyst was investigated using different fractions of FCC gasoline as raw material.The results showed that three main reactions were taking place during the hydrogenation process.Moreover,the fraction of 80¹30?contained olefins saturation without octane loss through isomerization of the paraffins and aromatization of the naphthenes.Therefore,80¹30?fraction was ideal FCC middle gasoline for hydrogenation on supported Ni₂P catalysts.However,components in FCC gasoline were complex existing a number of competing reaction,and the activity and stability of Ni₂P/?-Al2O3-SAPO-11catalysts needed to be improved.