Selected Process Alternatives for Biomass Refining: A Review

Abstract

Abstract:The role of biorefineries in the production of energy and chemicals from biomass of lignocellulosic nature is reviewed. Special attention is devoted to biorefinery schemes dealing with the fractionation of lignocellulosic raw materials by chemical treatments. The potential of hydrothermal treatments as the first stage of future biorefineries is discussed. Special attention is devoted to the low-volume, high-added value products that can be solubilized by this type of technology.

Hydrothermal processing, as an alternative for upgrading agriculture residues and marine biomass according to the biorefinery concept: A review

“…1 shows the scheme of a biorefinery using hydrothermal processing. This process has been mainly used as a pretreatment for bioethanol production; in recent researches, the use of a sequential process has been applied as an alternative of papermaking production, also as a technology for converting agro-food by-products into useful food ingredients [12,[65][66][67][68][69][70][71].…”

“…During the hydrothermal processing lignin and lignin-hemicellulose linkages can undergo degradation, partial depolymerization and profound re-localization. Moreover, the fraction of solubilized lignin depends on the operation conditions (severity of reactions conditions) and on the raw material (LCMs) [28,66,127]. Lora and Wyman (1978) and Bobleter and Concin (1979) cited by Garrote et al [28] and Zhang et al [187] suggested a two-phase mechanism for lignin reaction: (1) a very fast reaction where lignin fragments with low molecular weight and high reactivity are solubilized by breaking lignin-carbohydrate bonds into soluble fragments; (2) a slower reaction where the soluble fragments react with one another by recondensantion and lignin repolimerization, which also occurs in the presence of the organic acids liberated in the hydrothermal processing.…”

“…Soluble lignin being aromatic and possessing many chromophoric structural units strongly absorbs ultraviolet (UV) light and the absorbance at either 205 or 280 nm is the basis of several techniques for the quantitative determination of soluble lignin [188,189]. The partial depolymerization of lignin and breaking of lignin-hemicellulose linkages produced part of the phenolics present in the hydrothermal processing liquors [66,190]. Using hardwood as raw material, Marchessault et al [191] reported that the ether linkages of lignin are cleaved during hydrothermal processing causing a decrease in molecular weight and an increase in phenolic content.…”

“…Pourali et al [199] used subcritical water conditions and reported the production of eleven phenolic compounds (caffeic, ferulic, gallic, gentisic, p-coumaric, p-hydroxybenzoic, protocatechuic, sinapic, syringic, vanillic acids and vanillin) and concluded that the content of phenolic compounds increased with the temperature. Many beneficial effects on human health have been attributed to simple phenolics: oleuropein, hydroxytyrosol, caffeic acids (prevention of cardiovascular diseases); hydroxytyrosol, tyrosol, vanillin, vanillic acid, caffeic acids (prevention of tumoral diseases); p-coumaric acid, caffeic acid, ferulic acid (protection against LDL lipoprotein oxidation); gallic acid (skin protective ability); vanillin, (anti-inflammatory) [66,183,[200][201][202][203]. In regard to antioxidant activity, Tsubaki et al [204] reported the production of polyphenols above 200 1C, obtaining strong antioxidant activity using tea residues as raw material and microwave heating.…”

Lignocelluloses Feedstock Biorefinery as Petrorefinery Substitutes

“…While decreasing crude-oil reserves, enhanced demand for fuels worldwide, increased climate concerns about the use of fossil-based energy carriers, and political commitment, the focus has recently turned to develop the utilization of renewable energy resources [2]. Gullón et al [3] described the variety of problems on present social, economic and technological situation, which including: the fear for a shortening of the supplies of basic resources, as the population growth; the increasing per capita demands of the developing economies for goods and energy, derived from the increasing purchase power of the population; environmental challenges, especially those related to effects of greenhouse gas emissions (emphasis on CO2) on the global climate; the national security issues surrounding reliance on imported oil [4].…”