Conversion of dicyclopentadiene into high energy density fuel exo-tetrahydrodicyclopentadiene: An experimental and computational study

Abstract

The present study covers the optimization of reaction parameters in the conversion of dicyclopentadiene (DCPD) to exo-tetrahydrodicyclopentadiene (exo-THDCPD), emphasizing the isomerization reaction of endo-tetrahydrodicyclopentadiene (endo-THDPCD) to exo-THDCPD. This process involves the (i) hydrogenation of DCPD to endo-THDCPD over Pd/γ-Al2O3 catalyst and (ii) isomerization of endo-THDCPD to exo-THDCPD using AlCl3. The repeatability of the hydrogenation catalyst, Pd/γ-Al2O3 effectively, with > 98.5 % purity of endo-THDCPD, was established for 18 cycles without solvent. Reaction parameters for the isomerization reaction were optimized and found that 1 wt% of AlCl3 at 23.5 ℃ reaction temperature in dichloromethane (DCM) solvent is sufficient for the reaction to obtain > 99 % purity of exo-THDCPD. The computational and experimental studies reveal that DCM as a solvent is necessary with such a low amount of AlCl3 (i.e., 1 wt%) to isomerize endo-THDCPD to exo-THDCPD (purity > 99 %). DCM provides the best condition for monomeric AlCl3 to participate in the isomerization reaction. The calculated intermediates (cation + anion) energies (using DFT calculations) in different solvent environments were found to be in the order DCM < carbon tetrachloride < chloroform.