Kinetic, Spectroscopic, and Theoretical Assessment of Associative and Dissociative Methanol Dehydration Routes in Zeolites
Mechanistic interpretations of rates and in situ IR spectra combined with density functionals that account for van der Waals interactions of intermediates and transition states within confining voids show that associative routes mediate the formation of dimethyl ether from methanol on zeolitic acids at the temperatures and pressures of practical dehydration catalysis. Methoxy-mediated dissociative routes become prevalent at higher temperatures and lower pressures, because they involve smaller transition states with higher enthalpy, but also higher entropy, than those in associative routes. These enthalpy–entropy trade-offs merely reflect the intervening role of temperature in activation free energies and the prevalence of more complex transition states at low temperatures and high pressures. This work provides a foundation for further inquiry into the contributions of H-bonded methanol and methoxy species in homologation and hydrocarbon synthesis reactions from methanol.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1222912
- Journal Information:
- Angewandte Chemie, 126(45):12373-12377, Journal Name: Angewandte Chemie, 126(45):12373-12377
- Country of Publication:
- United States
- Language:
- English
Similar Records
Understanding methanol dissociative adsorption and oxidation on amorphous oxide films
Olefin methylation over iron zeolites and the methanol to hydrocarbons reaction