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Review of Physicochemical Properties and Analytical Characterization of
Lignocellulosic Biomass
(to be submitted to Renewable and Sustainable Energy Reviews)
Junmeng Cai *
,a
, Yifeng He
a
, Xi Yu
b
, Scott W. Banks
b
, Yang Yang
b
, Xingguang Zhang
c
,
Yang Yu
a
, Ronghou Liu
a
, Anthony V. Bridgwater
b
a
Biomass Energy Engineering Research Center, Key Laboratory of Urban Agriculture (South)
of Ministry of Agriculture, School of Agriculture and Biology, Shanghai Jiao Tong University,
800 Dongchuan Road, Shanghai 200240, People’s Republic of China
b
Bioenergy Research Group, European Bioenergy Research Institute, Aston University,
Birmingham, B4 7ET, United Kingdom
c
Department of Chemical Engineering, Nanjing Forestry University, 159 Longpan Road,
Nanjing 210037, People’s Republic of China
* Corresponding author: Junmeng Cai. Tel.: +86-21-34206624; Email: jmcai@sjtu.edu.cn.
Graphical abstract ............................................................................................................................................ 2
Abstract ........................................................................................................................................................... 2
1 Introduction .................................................................................................................................................. 3
2 Basis of analysis ........................................................................................................................................... 7
3 Physical properties ....................................................................................................................................... 9
3.1 Particle size ....................................................................................................................................... 9
3.2 Grindability ..................................................................................................................................... 12
3.3 Density ............................................................................................................................................ 13
3.3.1 Particle density ..................................................................................................................... 13
3.3.2 Bulk density .......................................................................................................................... 14
3.4 Flowability ...................................................................................................................................... 15
3.5 Moisture sorption ............................................................................................................................ 16
3.6 Thermal properties .......................................................................................................................... 18
3.6.1 Thermal conductivity............................................................................................................ 19
3.6.2 Specific heat ......................................................................................................................... 19
4 Chemical properties .................................................................................................................................... 20
4.1 Proximate analysis ........................................................................................................................... 20
4.1.1 General introduction ............................................................................................................. 20
© 2017, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
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4.1.2 ASTM standard method ........................................................................................................ 21
4.1.3 Thermogravimetric analysis method .................................................................................... 21
4.1.4 Typical results ....................................................................................................................... 24
4.2 Ultimate analysis ............................................................................................................................. 25
4.3 Energy content ................................................................................................................................. 29
4.4 Compositional analysis ................................................................................................................... 30
4.4.1 General introduction ............................................................................................................. 30
4.4.2 Sulfuric acid hydrolysis method ........................................................................................... 31
4.4.3 NIRS method ........................................................................................................................ 32
4.4.4 Kinetic method ..................................................................................................................... 33
4.4.5 Typical results ....................................................................................................................... 34
5 Summaries .................................................................................................................................................. 35
Acknowledgements ....................................................................................................................................... 40
References ..................................................................................................................................................... 40
Graphical abstract
Abstract
Lignocellulosic biomass is the most abundant and renewable material in the world for the
production of biofuels. Using lignocellulosic biomass derived biofuels could reduce reliance on
fossil fuels and contribute to climate change mitigation. A profound understanding of the
physicochemical properties of lignocellulosic biomass and the analytical characterization
methods for those properties is essential for the design and operation of associated biomass
conversion processing facilities. The present article aims to present a comprehensive review of
physicochemical properties of lignocellulosic biomass, including particle size, grindability,
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density, flowability, moisture sorption, thermal properties, proximate analysis properties,
elemental composition, energy content and chemical composition. The corresponding
characterization techniques for these properties and their recent development are also presented.
This review is intended to provide the readers systematic knowledge in the physicochemical
properties of lignocellulosic biomass and characterization techniques for the conversion of
biomass and the application of biofuels.
Key words: lignocellulosic biomass; physicochemical properties; biofuel; biomass conversion;
analytical characterization
1 Introduction
Biofuels offer the prospective to reduce the reliance on use of fossil fuels, address the fuel
security and environment issues, and favor some socioeconomic benefits such as sustainable
development and creating jobs [1]. According to International Energy Agency, biomass energy
accounts for about 14% of the world’s total primary energy supply [2]. Lignocellulosic biomass
is the most abundant and renewable material in the world for the production of biofuels [3],
which can be used as a fuel resource alternative to fossil resources.
Lignocellulosic biomass refers to plant dry matter, which is mainly composed of cellulose,
hemicellulose and lignin [4]. The lignocellulosic biomass feedstocks available for energy
purpose are mainly from the following sectors: agriculture, forest, and industry. Table 1 lists
various types of lignocellulosic biomass with some examples. Agricultural wastes and forest
residues are the most promising biomass feedstocks for their abundance and relatively low cost
[5].
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Table 1. Lignocellulosic biomass feedstocks available for energy purposes
Supply sector Type Examples
Agriculture Lignocellulosic energy crops Herbaceous crops (e.g. switchgrass, miscanthus, reed)
Crop residues crop straw (e.g. rice straw, wheat straw, corn stalk,
cotton stalk)
Oil, sugar and starch energy
crops
Rape seed, sugarcane, corn
Forest Dedicated forestry Short rotation plantations (e.g. willow, poplar,
eucalyptus)
Forestry by-products Barks; Wood blocks; Wood chips from tops and
branches; Wood chips from thinning; Logs from
thinning
Industry Lignocellulosic agro-
industrial residues
Rice husk, sugarcane bagasse, corn cob
Wood industry residues Industrial waste wood; Sawdust from sawmills
Other Lignocellulosic waste Lignocellulosic residues from parks and gardens (e.g.
prunings, grass)
Traditional use of lignocellulosic biomass has been limited to burning for cooking and
heating, which lead to significant negative environmental impacts such as land degradation and
desertification [6]. By means of thermochemical or biochemical conversion routes,
lignocellulosic biomass can be converted into energy or energy carriers. Thermochemical
conversion uses heat and chemical processes to produce energy products from biomass,
including combustion, pyrolysis, gasification, and liquefaction [7]. Biochemical conversion of
biomass involves the use of bacteria, microorganisms or enzymes to breakdown biomass into
gaseous or liquid fuels, such as biogas or bioethanol [8]. Typical biomass conversion
technologies and their primary products and end-uses are illustrated in Figure 1.
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Figure 1. Thermochemical and biochemical conversion of lignocellulosic biomass
The whole biomass-to-biofuel process includes the logistics, pretreatment and conversion
processes of lignocellulosic biomass [9]. The logistics process includes the collection, handling,
storage and transportation of biomass feedstocks. The pretreatment process contains the drying,
grinding and sieving of feedstocks. The conversion process includes feeding, conversion,
separation of intermediate products, collection and upgrading and collection of products. The
physicochemical properties of lignocellulosic biomass are essential data of reference for the
design and implementation of these processes (Figure 2). Table 2 lists the engineering
application of these properties [10, 11].
![Figure 4. Particle size distribution of (a) chopped switchgrass and (b) sorghum residue (data adapted from Refs. [27, 28])](/figures/figure-4-particle-size-distribution-of-a-chopped-switchgrass-2pkcb1v2.webp)
![Figure 6. Proximate analysis results of typical biomass feedstocks and coal samples with different ranks on dry basis (data were taken from [97-100])](/figures/figure-6-proximate-analysis-results-of-typical-biomass-1b4z3q8p.webp)
![Figure 8. CHO index values of typical biomass feedstocks on dry ash free basis (data adapted from Refs. [97, 104, 106])](/figures/figure-8-cho-index-values-of-typical-biomass-feedstocks-on-1wp6agv9.webp)
![Table 6. Compositional analysis results of typical lignocellulosic biomasses (data adapted from Refs. [17, 129, 130])](/figures/table-6-compositional-analysis-results-of-typical-242dlmai.webp)