Table of Contents
Journal of Applied Chemistry
Volume 2013, Article ID 838645, 9 pages
http://dx.doi.org/10.1155/2013/838645
Review Article

Recent Development in Chemical Depolymerization of Lignin: A Review

1Department of Chemical Engineering, University of North Dakota, Grand Forks, ND 58202, USA
2National Renewable Energy Laboratory, Golden, CO 80401, USA

Received 29 March 2013; Revised 21 June 2013; Accepted 24 June 2013

Academic Editor: Lingjie Meng

Copyright © 2013 Hai Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This article reviewed recent development of chemical depolymerization of lignins. There were five types of treatment discussed, including base-catalyzed, acid-catalyzed, metallic catalyzed, ionic liquids-assisted, and supercritical fluids-assisted lignin depolymerizations. The methods employed in this research were described, and the important results were marked. Generally, base-catalyzed and acid-catalyzed methods were straightforward, but the selectivity was low. The severe reaction conditions (high pressure, high temperature, and extreme pH) resulted in requirement of specially designed reactors, which led to high costs of facility and handling. Ionic liquids, and supercritical fluids-assisted lignin depolymerizations had high selectivity, but the high costs of ionic liquids recycling and supercritical fluid facility limited their applications on commercial scale biomass treatment. Metallic catalyzed depolymerization had great advantages because of its high selectivity to certain monomeric compounds and much milder reaction condition than base-catalyzed or acid-catalyzed depolymerizations. It would be a great contribution to lignin conversion if appropriate catalysts were synthesized.