Biorefinery review: Wide-reaching products through kraft lignin

Abstract

This review details the structure of lignin and curates information on the characteristics that this polymer must have for each specific use. Lignin is a by-product of the pulp and paper industry and the second most abundant biopolymer after cellulose. Approximately 50 million tons of lignin are produced worldwide annually, of which 98% to 99% is incinerated to produce steam, process energy. Just 1% to 2% of the lignin, derived from the sulfite pulp industry, is used in chemical conversion to produce lignosulfonates. Biorefining is a promising approach to promote the wider use of kraft lignin. However, using kraft lignin to produce high value-added products is a great challenge, due to its complex structure, low reactivity, and low solubility, which are factors that limit the lignin’s large-scale use in biorefineries. Recent studies show that kraft lignin can be used as lignosulfonates and dispersants, technical carbons, transportation fuels, bioplastics, and adhesives, but some technological hurdles must be overcome and several industrial tests must be developed to make these uses viable.

Controlled lignosulfonate depolymerizationviasolvothermal fragmentation coupled with catalytic hydrogenolysis/hydrogenation in a continuous flow reactor

“…29 Nowadays, the 1 st scenario is still the major application for technical lignin and Every year, from the principal 250 Mt, about ~70 Mt of technical lignin are separated, of which an estimated 95 % are burned to produce energy. 38,39 Among this quantity, approximately 2 Mt/y are only by the sulfite process. 21,38 In the sulfite pulping, debarked wood chips are treated with sulfite and bisulfite salts solution (Na is the major counter-ions to bisulfite) in acidic aqueous media (pH 1-5) at temperatures ranging from 125 to 190°C.…”

“…38,39 Among this quantity, approximately 2 Mt/y are only by the sulfite process. 21,38 In the sulfite pulping, debarked wood chips are treated with sulfite and bisulfite salts solution (Na is the major counter-ions to bisulfite) in acidic aqueous media (pH 1-5) at temperatures ranging from 125 to 190°C. 21,40 Within this process, the ether bonds in lignin are partially hydrolyzed and followed by sulfitization step (introducing -SO 3functionalities), or oxidative coupling to form parasitic C-C bonds.…”

Recovering Wood Waste to Produce Briquettes Enriched with Commercial Kraft Lignin

“…The worldwide lignin production is approximately 50 million tons [31] by-product have distinct adhesive characteristics and may be used as a densification binder [29]. The use of lignin as binder is relatively new and studies of this application as a binder have been done recently [28] [29] [32]- [38].…”

Release behavior of oxyfluorfen polyurea capsules prepared using PVA and kraft lignin as emulsifying agents and phytotoxicity study on paddy

“…High encapsulation would be achieved when the core/shell mass ratio was 2:1, and 10 wt% of the crosslinking monomer pentaerythritol tetraacrylate (PETRA) was used (49). Recent studies have shown that kraft lignin can also function as dispersants, bioplastics, and fuel for transportation (50).…”