Selective Hydrocracking And Isomerization Of N-alkanes Over ZSM-22 Composite Catalyst

Trying to find a renewable,sustainable and efficient green energy to replace the increasingly depleted fossil energy has become one of the most important issues in the word,and bio-aviation technology is one of the best choice.This paper focuses on how to improve the utilization of raw materials and the target product selectivity,which is important for the hydrocracking and isomerization of n-Alkanes over zeolite ZSM-22.In this study,we used ndodecane as the raw material and take a series modification measures to improve the catalytic performance of ZSM-22.We also mixed ZSM-22 with different molecular sieves and get a composite catalyst which have a better catalytic performance.Finally,we found the optimum reaction condition by a series of experiments.The conclusions of study are as follows:(1)The Na-ZSM-22 had no catalytic activity,but when we mixed it with H-ZSM-22 as a composite catalyst,its pore structure changed the reaction system balance,and the utilization of raw materials and the target product selectivity were improved.The conversion rate increased from 82.78% to 96.91%,and the yield increased from 37.79% to 42.23%.(2)We mixed H-ZSM-22 with H-Y to get a composite catalyst,and established a unique reaction path: n-dodecane ? ZSM-22 zeolite ? Y zeolite.The selectivity increased from 62.53% to 71.34%,and the yield increased from 59.47% to 63.06%.(3)According to the work we had done,the water vaporization could effectively restrain the strong acidity of ZSM-22 catalyst,and the selectivity increased from 51.40% to 70.59% and yield increased from 49.88% to 63.34%.We putted ZSM-22 in a caldron with appropriate water,then kept the temperature at 170 ? for 24 hours.The selectivity increased from 51.40% to 71.34% and the yield increased from 49.88% to 63.06%.(4)The activity of the catalyst was improved by loading Pt,and the conversion rate increased from 68.86% to 95.82% at 3.0 wt‰ Pt loading,when the yield increased from 29.50% to 68.17%.(5)The catalytic got the best performance when we kept the temperature at 295? and pressure at 3.0 MPa,the conversion rate reached 91.30%,the selectivity reached 84.24%,and the yield reached 76.90%.