Fluoride-treated IM-5 zeolite as a highly active catalyst for the production of jet fuels by the oligomerization of 1-hexene

Light alkenes oligomerization, performed in the presence of solid acid catalysts, is an important alternative for the production of clean jet fuels. For 1-hexene oligomerization, the current catalyst often suffers from low activity and selectivity. The developed process is upgraded by zeolite catalyst, targeting high-concentration of jetrange hydrocarbons. An efficient and selective IM-5 zeolite-derived catalytic system has been developed for the oligomerization of 1-hexene. The treatment in an aqueous NH4F solution led to dealumination without structure degradation. The IM-5 zeolite with a unique two-dimensional IMF structure and 2.5 nm nanoslab showed rapid diffusion ability than ZSM-5 zeolite. Enhance acidities were observed in the NH4F-treated IM-5 zeolites owing to fluoride residue and the removal of Al atoms. The strong Brunsted acid sites exerted a positive effect on both the cracking and the oligomerization reactions with the increasing of the yields of dimers. The contact time and partial pressure between the 1-hexene and the IM-5 zeolites were used to analyze the competition of cracking reactions. High 1-hexene conversion (62%), optimal oligomerization to C-3-C-5 ratio (O/C = 32), and reasonable stability were obtained over the etched IM-5 catalyst at 240 degrees C, 4 MPa, and the flow rate of N-2 was 50 mL/min.

Automated summary

Light alkenes oligomerization is an important method for producing clean jet fuels, but the current catalyst used for 1-hexene oligomerization has low activity and selectivity. In this study, an efficient and selective IM-5 zeolite-derived catalyst system was developed for 1-hexene oligomerization. Treatment with an aqueous NH4F solution resulted in dealumination of IM-5 zeolite without structure degradation. The NH4F-treated IM-5 zeolite exhibited enhanced acidity and showed rapid diffusion ability. The strong Brunsted acid sites in the catalyst promoted both cracking and oligomerization reactions. The contact time and partial pressure between 1-hexene and IM-5 zeolite were analyzed to understand the competition of cracking reactions. High conversion of 1-hexene, optimal oligomerization ratio, and reasonable stability were achieved using the etched IM-5 catalyst.