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Steam Explosion –How it works

(the chemistry behind it all)…


Steam explosion is an autohydrolysis process. It’s effects on biomass include:

  1. cleavage of some accessible glycosidic links.
  2. cleavage of beta-ether linkages of lignin.
  3. cleavage of lignin-carbohydrate complex bonds.
  4. minor chemical modification of lignin and carbohydrates.


In order to obtain cellulose, hemicelluloses, and lignin from exploded fibers, fractionation must be carried out.


The most dramatic consequences of steam explosion on the structure and behavior of lignocellulosic materials is the solubility of the biomass in neutral or alkali solvents.


Fractionation of steam exploded biomass into water-soluble, alkali-soluble, and insoluble fractions by treatment with first hot water and then hot alkali has been studied extensively.


Normally, steam assisted fractionation of biomass by steam explosion produces two useful polymer fractions. First is a partially hydrolyzed cellulose fraction which normally results in a 40-50% yield. Second is a pure, alkali-soluble, lignin fraction which results in a 15-25% yield. (Yield depends primarily on the severity of the steam explosion process performed.)