Hydrothermalconversionoflignin Areview 木质素热化学转化综述

Hydrothermal conversion of lignin:A review

Shimin Kang,Xianglan Li,Juan Fan,Jie Chang n

The Key Lab of Enhanced Heat Transfer and Energy Conservation,Ministry of Education,School of Chemistry and Chemical Engineering,

South China University of Technology,Guangzhou,Guangdong510640,China

a r t i c l e i n f o

Article history:

Received30October2011

Received in revised form

24May2013

Accepted14July2013

Available online7August2013

Keywords:

Lignin

Hydrothermal conversion

Liquefaction

Gasification

Wet oxidation

Biomass

a b s t r a c t

Lignin is a carbon-rich renewable source owning aromatic structure units,which is an important

constituent in biomass.Hydrothermal conversion of lignin is widely studied as a promising method to

produce not only bioenergy but also value-added useful chemicals.Fuel gas,aromatic aldehydes and

phenolic products can be obtained from lignin hydrothermal gasification,wet oxidation and hydro-

thermal liquefaction,respectively.This article discusses and compares the three methods of lignin

hydrothermal conversion,including their process parameters,possible conversion routes,catalysts,

application of products.Effects of hot-compressed organic solvent–water mixture solution on conversion

of lignin and effects of lignin in biomass hydrothermal conversion are commented.Wet oxidation of

lignin is an efficient mean of recovering value-added aromatic aldehydes,especially vanillin.Hydro-

thermal liquefaction of lignin is a promising way of recovering phenolics-rich bio-oils.Both aromatic

aldehyde and phenolic compound are important chemical intermediates.There are strict requirements of

process conditions and relative high costs to get fuel gas from direct hydrothermal gasification of lignin.

However,further studies on improving gasification of lignin seem necessary in order to get fuel gas from

hydrothermal gasification of the whole biomass.

&2013Elsevier Ltd.All rights reserved.

Contents

1.Introduction (547)

2.Hydrothermal conditions (547)

3.Wet oxidation of lignin (548)

3.1.Catalysts (548)

3.2.Affecting conditions (549)

3.3.Separation (549)

4.Hydrothermal gasification (549)

4.1.Products and separation (549)

4.2.Affecting conditions (550)

4.3.Catalysts (550)

4.4.Partial oxidation SCW gasification (551)

5.Hydrothermal liquefaction (551)

5.1.Liquefaction products (551)

5.2.Liquefaction of model compounds (552)

5.3.Application and separation (552)

5.4.Catalysts (552)

6.Hot-compressed organic solvent–water solution conversion (553)

7.Lignin hydrochar (553)

8.Effects of lignin in biomass hydrothermal conversion (553)

9.Mechanism of Hydrothermal gasification,liquefaction,and wet oxidation (554)

10.Summary (555)

Contents lists available at ScienceDirect

journal homepage:/locate/rser

Renewable and Sustainable Energy Reviews

1364-0321/$-see front matter&2013Elsevier Ltd.All rights reserved.

/10.1016/j.rser.2013.07.013

n Corresponding author.Fax:+862087112448.

E-mail address:changjie@(J.Chang).

Renewable and Sustainable Energy Reviews27(2013)546–558