Inhibition of terminal C[sbnd]C bonds cleavage drives high selectivity of n-alkane hydroisomerization

Abstract

Herein we develop a solvent-free one-pot synthesis strategy to simultaneously modify the size effect of metal sites and structural acidity on bifunctional catalysts to in-situ grow platinum nanoparticles (Pt-NPs ∼ 1 nm and ∼ 20 nm) of disparate sizes in the molecular sieve framework without relying on any ligand assistance, causing skeletal defects while exhibiting excellent catalytic performance in n-alkane hydroisomerization. It maintains almost 100 % isomerization selectivity at conversions below 90 %, with performance far superior to that of the conventional catalysts (Pt-NPs ∼ 1 nm). The reason for high selectivity and high liquid yields was revealed by structural characterizations and density functional theory calculations, i.e., the inhibition of terminal CC bond cleavage over n-dodecane chains adsorbed on the defect-containing catalysts and the higher energy barrier of transition state for producing gaseous small molecules, while the size of Pt-NPs may not be the main factor in determining the performance of n-alkane hydroisomerization.