Issue 17, 2017

Molecular modelling approach to elucidate the thermal decomposition routes of vanillin

Abstract

The presence of very high amounts of oxy-components in unprocessed bio-oil after thermochemical conversion of lignocellulosic biomass is an undesirable property of bio-oil. This results in severe drawbacks for raw bio-oil which are considered to be undesirable characteristics of any fuel, e.g., low heating value, corrosiveness, high viscosity, and low stability. Therefore, it is necessary to eliminate oxygen atoms from the components of bio-oil. On the other hand, the very high number of oxy-components in unprocessed bio-oil offers an excellent platform to acquire various specialty chemicals. Therefore, in this work, vanillin (4-hydroxy-3-methoxy-benzaldehyde) is considered as a model compound of lignin-derived bio-oil, and various chemical conversions are conducted to achieve lower molecular weight hydrocarbon fractions and several important intermediates, e.g., benzene, guaiacol, o-cresol, p-hydroxybenzaldehyde, m-methoxybenzaldehyde, phenol and o-quinonemethide. Bond dissociation energy studies were carried out to observe the potential chemical breakage sites of vanillin. Chemical reaction mechanisms are proposed according to the various bond dissociation possibilities, and potential energy surfaces are reported for each reaction scheme. The production of guaiacol from vanillin using atomic hydrogenation at the aromatic carbon of the Caromatic–CHO bond of vanillin followed by formyl group removal was found to be the pathway requiring the lowest activation energy (only 10.13 kcal mol−1). The present results are in accordance with their experimental counterparts wherever applicable. The thermochemical phenomena of these reactions were studied in a wide temperature range, i.e., 598 to 898 K for the gas phase and 298 to 498 K for the aqueous phase, at a fixed pressure of 1 atm. The aqueous phase environment was created by a SMD model using water as the solvent. All reaction schemes in both phases were favourable under all temperature conditions except for the formation of phenol from vanillin via the formation of 5-formylsalicylaldehyde, as reported in reaction schemes 7a and 7a1.

Graphical abstract: Molecular modelling approach to elucidate the thermal decomposition routes of vanillin

Supplementary files

Article information

Article type
Paper
Submitted
06 Jun 2017
Accepted
27 Jun 2017
First published
04 Jul 2017

New J. Chem., 2017,41, 8845-8859

Molecular modelling approach to elucidate the thermal decomposition routes of vanillin

A. M. Verma and N. Kishore, New J. Chem., 2017, 41, 8845 DOI: 10.1039/C7NJ02004J

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