Highly selective skeletal isomerization of cyclohexene over zeolite-based catalysts for high-purity methylcyclopentene production

Abstract

Cyclohexene skeletal isomerization towards methylcyclopentene is an economically favorable process due to the higher added value of the product. Traditional oxide-based catalysts face the challenge of achieving both high activity and stability. In this work, cyclohexene skeletal isomerization is achieved under mild conditions over designed zeolite-based catalysts with 96.8 wt.% liquid yield, 95.8 wt.% selectivity towards methylcyclopentene and satisfactory stability for multiple runs. The favorable performance is attributed to the unique acidic, structural and morphological features of the optimized cobalt/NaUZSM-5 catalyst. Further experimental data and DFT studies suggest that a carboncationic mechanism might be followed and that the reaction mainly occurs within the internal pores of the zeolite structures.

Mechanistic insights into positional and skeletal isomerization of cyclohexene in the H-BEA zeolite

“…As one of the widely used and important model cycloalkene compounds in the petrochemical industry, cyclohexene obtained from the hydrogenation of benzene has been studied both experimentally and theoretically. [4][5][6][7] For the acid-catalyzed positional isomerization of cycloalkenes within zeolites, the initial step is the protonation of the electron-rich p bond by the acidic proton (H B ) of the BAS, 8,9 generating one carbenium intermediate. Depending on the attached carbon atom (C1 or C2) by H B , there are two isomers for the carbenium cation.…”

DeepCV: A Deep Learning Framework for Blind Search of Collective Variables in Expanded Configurational Space

“…A particularly well-understood aspect of the conformational analysis is concerned with molecules containing six-membered rings. The importance of such molecules in many classes of natural products has been widely studied, ,, especially cyclohexene and its derivatives. , A major reason for the depth of study of conformational change is that it lays a fundamental basis for understanding complex molecules that mostly are made of small building blocks. Having been investigated and characterized by experimental techniques (see Table for data and corresponding references), cyclohexene undergoes the conformational transition from the half-chair form to the twist boat form (see Figure ) by a medium amount of activation energy (∼5.30–10.29 kcal/mol, depending on the stability of the measured half-chair form and the condition of the experimental technique).…”