Delignification of wood

Sulfolane is a water-soluble biodegradable and highly polar compound valued for its solvent properties. Approximately 20 million pounds of sulfolane are consumed annually in applications that include delignification of wood, polymerization and fiber spinning, and electroplating bathes.It is a solvent for selectively extracting aromatics from reformates and coke oven products. 

In pulp and paper processing, anthraquinone (AQ) accelerates the delignification of wood and improves liquor selectivity. The kinetics of the liquid-phase oxidation of anthracene (AN) to AQ with NO2 in acetic acid as solvent has been studied by Rodriguez and Tijero (1989) in a semibatch reactor (batch with respect to the liquid phase), under conditions such that the kinetics of the overall gas-liquid process is controlled by the rate of the liquid-phase reaction. This reaction proceeds through the formation of the intermediate compound anthrone (ANT) ... 

In pulp and paper processing, antbraquinone accelerates delignification of wood and im-... 

Thermodynamically controlled self-assembly of an equilibrated ensemble of POMs with [AlVWnO40]6 as the main component could act as a catalyst for the selective delignification of wood (lignocellulose) fibers (Figure 13.2) [55], Equilibration reactions typical of POMs kept the pH of the system near 7 during the catalysis that avoided acid or base degradation of cellulose. 

Figure 13.2 Proposed catalytic cycle for the selective delignification of wood (lignocellulose) fibres with an equilibrated ensemble of POMs. (From Weinstock, I. A. et al., Nature, 414, 191,2001.)...

Goto et al. [50], also employed the linear-driving-force model for describing the high pressure delignification of wood with supercritical tert.-butyl alcohol, proving that it is a reasonable approximation. 

The sulfite process for delignification of wood in the paper industry involves heating with acidic sulfite solutions at elevated temperatures under pressure. Under such conditions, oxidation occurs to a certain extent, and presumably, the sulfite is partly reduced to sulfide. The composition of the liquors resulting from the treatment of cellulose and hemicelluloses, and alditols with sulfite in acid medium has been described (Ref. 1, p. 1150). 

Understanding the MnP and LiP mechanism is important not only from a fundamental point of view but also because delignification of wood chips leaves behind pulp, the fibrous polysaccharides (hemicellulose and cellulose) that... 

Demirbas, A., Aqueous glycerol delignification of wood chips and ground wood. Bioresource Technol 1998,63 (2), 179-185. 

Nahum L (1965) Delignification of wood by hydrogenation in presence of dicobalt octacarbonyl Ind Eng Chem 4 71-74... 

Bialski AM, Luthe CE, Fong JL, Lewis NG (1986) Sulphite-promoted delignification of wood identification of paucidisperse lignosulphonates Can J Chem 64 1336-1344 Bourbonnais R, Paice MG (1987) Oxidation and reduction of lignin-related aromatic compounds by Aureobasidium pullulans Appl Microbiol Biotechnol 26 164-169 Braithwaite A, Smith FJ (1985) Chromatographic methods Chapman and Hall, New York, 258-266... 

Lignin condensation reactions have been studied for many years, mainly because they possibly interfere with efficient delignification of wood. Numerous model compound studies established the various types of condensation reactions that may occur between lignin fragments (1-5) or between lignin and carbohydrates (1,2,6,7) during alkaline pulping. An important class of condensation reactions involves formaldehyde. 

Supercritical fluid solvents have been tested for reactive extractions of liquid and gaseous fuels from heavy oils, coal, oil shale, and biomass. In some cases the solvent participates in the reactions, as in the hydrolysis of coal and heavy oils with water. Related applications include conversion of cellulose to glucose in water, delignification of wood with ammonia, and liquefaction of lignin in water. 

The name holocellulose was assigned by Ritter and Kurth to the residue obtained after delignification of wood by alternate treatments with... 

Renard, J. J., Mackie, D. M., Bolker, H. L, and Clayton, D. W., Delignification of wood using pressurized oxygen. II. Mechanism of transfer of the reagents into the wood structure, Cellulose Chem. Technol. 9(4), 341-352 (1975). 

Extensive research by Dimmel and coworkers has shown that another mechanism is also possible between AHQ and QMs. They propose that single electron transfer (SET) chemistry promotes the delignification of wood [52]. As is the case for the adduct mechanism, this proposed chemistry is based solely on model compound studies and can account for coniferyl alcohol-type prodncts. Evidence for SET chemistry comes from a combination of studies involving electrochemistry... 

I Dill, G Kraepelin. Palo Podrido Model for extensive delignification of wood by Ganoderma applanatum. Appl Environ Microbiol 52 1305-1312, 1986. 

Sun, N., Rahman, M., Qin, Y, Maxim, M.L., Rodriguez, H. and Rogers, R.D., Conplete dissolution and partial delignification of wood in the ionic liquid l-ethyl-3-methylimidazolium ethanoate. Green Chem. 11, 646-655 (2009). 

---