Reducing the diffusion barriers of Pt/Beta catalyzed n-hexane isomerization by SBA-15 addition and high-energy milling

Aiming at improving reaction selectivity of zeolite Beta-catalyzed isomerization of normal alkane, we reported a facile but efficient route to prepare the Beta@SBA-15 composite supports with low surface diffusion barriers in isomers formation from normal alkane. Microporous Beta zeolite and mesoporous SBA-15 zeolite were physically mixed and milled by high-energy planetary ball-mill. The addition of SBA-15 and milling, which have little effect on the acid properties of Beta zeolites, disaggregate the Beta particles and anchor the Beta nanocrystals on the surface of SBA-15 mesostructure. The apparent diffusivities of 2-methyl pentane measured by zero-length column method increased by 50%. n-Hexane isomerization tests show that the Pt/Beta@SBA-15 catalysts exhibit much higher selectivity to isomers, especially the dibranched isomers and lower selectivity to cracking reaction, owning to the reduced transport limitation of composite supports.

Automated summary

In order to improve the selectivity of zeolite Beta-catalyzed isomerization of normal alkane, a simple and efficient route to prepare Beta@SBA-15 composite supports was reported. The addition of SBA-15 and the milling process disaggregated the Beta particles and anchored the Beta nanocrystals on the surface of SBA-15. This resulted in a 50% increase in apparent diffusivities and higher selectivity to isomers in n-hexane isomerization tests.