Bifunctional catalysts based on hierarchical SAPO-41 nanosheet for Highly-efficient hydroisomerization of n-Hexadecane

Conversion of long-carbon chain n-alkanes into iso-alkanes is a key technology to improve the low-temperature fluidity of petroleum-based diesel and lubricating oil, as well as produce second-generation biodiesel from vegetable oils. Developing a highly efficient bifunctional catalysts is the key to realize this process. In this work, a series of hierarchical silicoaluminophosphate molecular sieves SAPO-41 nanosheet (S41-xBCl) were synthesized by using various amounts of 1-butyl-3-methylimidazolium chloride ionic liquid (BMIMCl) as a crystal growth inhibitor. The bifunctional catalysts Pd/S41-xBCl with merely 0.1 wt% Pd loading on the S41-xBCl samples were prepared by wetness impregnation, and the catalytic performance for hydroisomerization of n-hexadecane was tested. The catalytic performance of Pd/S41-xBCl markedly improved because of the enhanced diffusion properties of reactants and iso-alkene intermediates, as well as the realizing synergistic catalysis of metal and acid sites. The yield of iso-hexadecane over the catalyst Pd/S41-2BCl were as high as 83.4% at n-hexadecane conversion of 94.6%. This efficient catalyst with lower noble metal loadings has wide application potential in the production of petroleum-based diesel and green biodiesel with excellent low-temperature fluidity.