Issue 14, 2011

Structures and reaction mechanisms of glycerol dehydration over H-ZSM-5 zeolite: a density functional theory study

Abstract

The initial stage of glycerol conversion over H-ZSM-5 zeolite has been investigated using density functional theory (DFT) calculations on an embedded cluster model consisting of 128 tetrahedrally coordinated atoms. It is found that glycerol dehydration to acrolein and acetol proceeds favourably via a stepwise mechanism. The formation of an alkoxide species upon the first dehydration requires the highest activation energy (42.5 kcal mol−1) and can be considered as the rate determining step of the reaction. The intrinsic activation energies for the first dehydration are virtually the same for both acrolein and acetol formation, respectively, suggesting the competitive removal of the primary and secondary OH groups. A high selectivity to acrolein at moderate temperatures can be attributed to the selective activation of the stronger adsorption mode of glycerol through the secondary OH group and the kinetically favoured subsequent consecutive steps. In addition, the less reactive nature of acrolein relative to acetol precludes it from being converted to other products upon conversion to glycerol. In accordance with typical endothermic reactions, the forward rate constant for glycerol dehydration significantly increases with increasing reaction temperature.

Graphical abstract: Structures and reaction mechanisms of glycerol dehydration over H-ZSM-5 zeolite: a density functional theory study

Supplementary files

Article information

Article type
Paper
Submitted
05 Sep 2010
Accepted
27 Jan 2011
First published
03 Mar 2011

Phys. Chem. Chem. Phys., 2011,13, 6462-6470

Structures and reaction mechanisms of glycerol dehydration over H-ZSM-5 zeolite: a density functional theory study

K. Kongpatpanich, T. Nanok, B. Boekfa, M. Probst and J. Limtrakul, Phys. Chem. Chem. Phys., 2011, 13, 6462 DOI: 10.1039/C0CP01720E

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements