A Study Aimed at Understanding the AQ/Polysulfide Synergistic Effect in Alkaline Pulping

Abstract

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A guide to lignin valorization in biorefineries: traditional, recent, and forthcoming approaches to convert raw lignocellulose into valuable materials and chemicals

“…[171][172][173] In some congurations, soda pulping implements the use of anthraquinone that simultaneously stabilizes polysaccharides against peeling reactions and catalyzes the cleavage of b-O-4 ′ bonds in lignin. 150,174,175 Anthraquinone (21) acts as a redox shuttle between carbohydrates and lignin (Fig. 14).…”

Catalytic Strategies Towards Lignin-Derived Chemicals

“…Therefore, soda pulping is primarily used for the fractionation of herbaceous feedstock (e.g., perennial grasses, agricultural residues), which typically possess a more accessible structure, a lower lignin content, and a higher amount of alkali-unstable ester linkages [62,63]. To increase the fractionation efficiency during soda-pulping, anthraquinone is often used, because it can act as a redox shuttle to promote ether bond cleavages (reductive) and stabilize the carbohydrate fraction (oxidative) [61,68]. A major advantage of the soda pulping process is the production of a more valuable sulphur-free lignin, thus avoiding catalyst poisoning or bad odors (often linked to sulphur) during downstream lignin processing [63,69].…”

A larch biorefinery: Influence of washing and PS charge on pre-extraction PSAQ pulping

“…Polysulfide (PS) and anthraquinone (AQ) are well-known pulping additives to increase pulp yield. PS and AQ oxidize the reducing end groups of polysaccharides to aldonic acid groups, thus stabilizing the polysaccharides against peeling reactions (Teder 1969;Dimmel et al 2003). AQ additionally accelerates the delignification rate of pulping (Dimmel et al 2003).…”

“…PS and AQ oxidize the reducing end groups of polysaccharides to aldonic acid groups, thus stabilizing the polysaccharides against peeling reactions (Teder 1969;Dimmel et al 2003). AQ additionally accelerates the delignification rate of pulping (Dimmel et al 2003). In softwood, the yield is enhanced by higher retention of glucomannans due to PS and better preservation of cellulose due to AQ (Pekkala 1986).…”

“…In softwood, the yield is enhanced by higher retention of glucomannans due to PS and better preservation of cellulose due to AQ (Pekkala 1986). A synergism exists when PS and AQ are used together in alkaline pulping (Dimmel et al 2003;Pekkala 1986;Luthe and Berry 2005;Jiang 1995;Berthold et al 1999;Sturgeoff and Bernhard 1998;Li et al 1998). In PSAQ, pulping glucomannan is the main hemicellulose that contributes to the yield increase (Pekkala 1986;Luthe and Berry 2005;Jiang 1995).…”