Molecular dimensions of tetrahydrodicyclopentadiene isomers and shape selectivity of zeolitic catalysts

Acid-catalyzed isomerization of tetrahydrodicyclopentadiene upon zeolitic catalysts with different pore channels was studied. With the aid of ACD/ChemSketch 5.0, the dimensions of three tetrahydrodicyclopentadiene isomers are estimated to compare with the channels sizes of zeolitic catalysts. The experimental data, comparisons between molecules dimensions and channel sizes show that reactant selectivity is the reason why HZSM-5 and H-β show no activities at lower temperature. Because of large pore channels (0.74 nm), HY zeolites have sufficient activities for isomerization of tetrahydrodicyclopentadiene to form both exo-tetrahydrodicyclopentadiene and adamantane.