Patents Assigned to Societe Generale de Brevets Industriels et Ohimiques
  • Patent number: 4135967
    Abstract: Wood chips are digested at a temperature above 100.degree. C in contact with a solution of a hydroxide or salt of an alkali metal or alkaline earth metal or ammonium in a solvent which boils above 100.degree. C at atmospheric pressure, such as ethylene glycol. The cellulose pulp is then separated from the dissolved lignin. The dissolved lignin may be precipitated and removed from the solvent and the solvent may then be recycled, so that there is no waste spent liquor. Examples of salts which may be used are sodium phenoxide and a combination of sodium bisulfite and an aldehyde or a ketone.
    Type: Grant
    Filed: February 28, 1977
    Date of Patent: January 23, 1979
    Assignee: Societe Generale de Brevets Industriels et Ohimiques
    Inventor: Andre Fogarassy