Alkali-acid treated hierarchical Pt/Beta bifunctional catalyst for higher selectivity of multi-branched i-heptane in n-heptane hydroisomerization

Pt/Beta catalyst was prepared by the impregnation method of introducing Pt atoms on Beta zeolite which post-treated with appropriate concentration alkali-acid. XRD, N₂ adsorption desorption, SEM, TEM, Py-IR, XRF, and MAS NMR were used to characterize the physicochemical properties including textural characters and acidity, and then the isomerization performance of the catalyst was evaluated in a micro fixed bed device using n-heptane as a medal compound. Test and evaluation results indicated that the modified Pt/beta catalyst exhibited higher multi-branched i-heptane yield than the parent sample due to the better structure activity relationship of the catalyst by introducing hierarchical structures and enlarge the channel of Beta zeolite framework. Indeed, the alkali-acid treated Pt/Beta catalysts exhibited 24.6% of the highest multi-branched i-heptane yield which was 9.3% higher than the parent catalyst at the n-heptane conversion rate of 85.0%. The regulation of zeolite on pore hierarchy has obvious advantages in the hydroisomerization process, which can improve the composition of multi-branched isomers with high octane number effectively as well as supply raw materials for the chemical industry.

Graphical Abstract