The Research Of N-Hexadecane Hydroisomerization Over Pt-based Catalyst

Hydroisomerization of long-chain alkanes has broad application prospect and great development potential in the fields of biomass fuel production,diesel oil and lubricating oil dewaxing and Fischer-Tropsch synthetic oil quality improvement.In this paper,hydroisomerization of n-hexadecane on the Pt-based catalyst was studied.First,by investigating Pt-based catalysts supported by ZSM-22,SAPO-11,HY and A1MCM-41,Pt/SAPO-11 was found to have the best reaction performance.The analysis shows that acid strength of the molecular sieve is the primary factor to determine the activity of catalyst,and the acid sites content also has an important influence on the activity.The pore structure of molecular sieve will affect the selectivity of isomeric hexadecane.After modification by chemical liquid deposition of tetraethyl silicate,the specific surface area and pore volume of the molecular sieve decreased,and acid sites also decreased,but the selectivity of monomethyl isomeric hexadecane increased from 49.2%to 54.5%.Secondly,through the study on the loading amount of Pt on tetraethyl silicate modified SAPO-11 molecular sieve,it was found that after the loading of Pt,the number of middle strong acid sites and strong acid sites increased,while the specific surface area and pore volume decreased to different degrees.With the increase of Pt loading,the distribution of PtOx species on the surface of molecular sieve also increased.Based on the Pt loading of 0.35wt%and Mg as the metal additive,it was also found that the selectivity of isomeric hexadecane reached to 74.4%.Finally,the effect of reaction conditions on the catalyst performance was studied.Under the optimal reaction conditions,the stability of the catalyst was evaluated.Within 360 hours,the conversion of n-hexadecane was maintained at 70%-80%,and the selectivity of isomeric hexadecane was also maintained at about 70%.