Pyrolysis of Wood/Biomass for Bio-oil:  A Critical Review

Abstract

Fast pyrolysis utilizes biomass to produce a product that is used both as an energy source and a feedstock for chemical production. Considerable efforts have been made to convert wood biomass to liquid fuels and chemicals since the oil crisis in mid-1970s. This review focuses on the recent developments in the wood pyrolysis and reports the characteristics of the resulting bio-oils, which are the main products of fast wood pyrolysis. Virtually any form of biomass can be considered for fast pyrolysis. Most work has been performed on wood, because of its consistency and comparability between tests. However, nearly 100 types of biomass have been tested, ranging from agricultural wastes such as straw, olive pits, and nut shells to energy crops such as miscanthus and sorghum. Forestry wastes such as bark and thinnings and other solid wastes, including sewage sludge and leather wastes, have also been studied. In this review, the main (although not exclusive) emphasis has been given to wood. The literature on wood/biomass pyrolysis, both fast and slow, is surveyed and both the physical and chemical aspects of the resulting bio-oils are reviewed. The effect of the wood composition and structure, heating rate, and residence time during pyrolysis on the overall reaction rate and the yield of the volatiles are also discussed. Although very fast and very slow pyrolyses of biomass produce markedly different products, the variety of heating rates, temperatures, residence times, and feedstock varieties found in the literature make generalizations difficult to define, in regard to trying to critically analyze the literature.

Biofuels from Microalgae

“…21 Examples include the twophase conversion reaction of fructose to 5-hydroxymethylfurfural, 59 fermentative production of ethanol from sugars derived from cellulose and semi-cellulose, 60 and bio-oils and/or biosyngas by the pyrolysis/gasification of woods or other types of biomasses. 61 Microalgae have the capacity of producing a vast array of high-value bioactive compounds that can be used as pharmaceutical compounds, health foods, and natural pigments. 62,63 Some well-studied examples include acetylic acids, b-carotene, 57,64 vitamin B, 65 ketocarotenoid astaxanthin, 66 polyunsaturated fatty acids, 67,68 and lutein 54,69 (see Table 1).…”

Thorough Chemical Modification of Wood-Based Lignocellulosic Materials in Ionic Liquids

“…The sharp signals at 147.6, 148.2, and 149.8 ppm are artifacts (see text). Table 1) with 65% WPG, 92.6% DS, in chloroform-d); (B) benzoylated spruce TMP (entry B2, Table 2) with 150% WPG, 94.0% DS in DMSO-d 6 ; (C) carbanilated spruce TMP (entry C5, Table 3) with 165% WPG, 89.7% DS in DMSO-d 6 ).…”

“…To further probe the structure of the obtained acetylated, benzoylated, and carbanilated wood derivatives, the 1 H NMR spectra of these materials that displayed the highest WPG values were obtained in deuterated chloroform or DMSO-d 6 ( Figure 5). The appearance of a large acetate -CH 3 signal is apparent in Figure 5A, which demonstrates the high DS of acetylation on spruce wood.…”

“…5 Although wood has long been used as a raw material for building, fuel, and various other uses, its potential for conversion to conventional biofuels (e.g., bioethanol) and production of commodity chemicals and biodegradable materials has drawn much attention recently, in view of developments in bioengineering and catalytic chemistry. 6 During the past four decades, the heterogeneous chemical modification of wood has been intensively studied with the aim of improving or modifying its compatibility with thermoplastics, dimensional stability, and resistance to decay. These modifications were always achieved at low efficiency due to the insolubility of the lignocellulosic materials under standard solvation conditions and the use and/ or release of environmentally unsustainable reagents, thus limiting potential commercial applications.…”

Adsorption of metal ions on lignin

“…More than 50 × 10 4 metric/tonnes/year of lignin are produced worldwide by pulping [28,29]. About 90-95% of the reactive lignin biopolymer is solubilized to oligomers that contribute to the pollution load.…”