Organic compounds -- part of the class 532-570 series – Organic compounds – Cyclopentanohydrophenanthrene ring system containing
Reexamination Certificate
2000-09-01
2002-10-15
Badio, Barbara P. (Department: 1616)
Organic compounds -- part of the class 532-570 series
Organic compounds
Cyclopentanohydrophenanthrene ring system containing
C203S060000, C203S063000
Reexamination Certificate
active
06465665
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a continuous process of high yield for recovering high purity sterol mixtures from mixtures of neutral compounds obtained form black liquor soap skimings of the cellulose pulping industry or from tall oil pitch.
BACKGROUND OF THE INVENTION
Black-liquor soaps are by-products of the Kraft pulping process of pine and other woods. Typically, during the Kraft process, wood chips are digested for two hours at 170° C. in an aqueous liquor containing sodium hydroxide and sodium sulfide. The digestion delignifies wood and produces a dark aqueous suspension called black liquor, which along with lignin contains cellulose pulp, rosin and fatty acid sodium soaps, a series of neutral organic products such as sterols, diterpenes, fatty alcohols, stilbenes, sterol and fatty alcohol esters and products resulting from lignin degradation. Under these conditions, the cellulose is stable and remains in suspension in the black liquor. When digestion is finished, the cellulose pulp is separated from the black liquor and washed. The pulp can be used as such or subjected to later purification processes.
Black liquor must be recovered for both economic and environmental reasons. To this end, the liquor is concentrated by evaporation to a concentration of about 23-32% in weight of black liquor solids. From said black liquor solids, fatty acid and rosin acid soaps are separated along with a series of hydrophobic or neutral matter suspended in these soaps and concentrated on the top of the container where they are removed or skimmed off. In technical literature, this fraction is called “skimmings”. Other terms used for the same fraction are “tall oil soap” or “CSS” (Crude Sulfate Soap) or “BLSS” (Black Liquor Soap Skimmings).
Generally the skimmings contain between 30 and 50% of water. The solid matter is a complex mixture of rosin acid and fatty acid sodium soaps and a series of hydrophobic compounds comprising sterols, stanols, fatty alcohols, diterpenes, stilbenes and non-saponified sterol esters, stanol esters and fatty alcohol esters, which together may constitute up to 25% of the skimmings solids. The neutral matter of black liquor soaps can be separated from the rosin acid and fatty acid soaps by means of solvent extraction processes known in the state of art, and also by means of molecular distillation as disclosed in Chilean Patent Application 873/98.
The mixture of neutral compounds obtained from black liquor soap usually also contains varying amounts of esters of sterols and esters of long chain aliphatic alcohols or fatty alcohols not saponified during the pulping process. When the mixture of neutral compounds is fully saponified and the soaps formed are separated from the saponified mixture, a mixture of unsaponifiable material is obtained. Another source of neutral matter is tall oil pitch. In this invention, the terms “mixture of neutral matter” or “neutral matter” means a mixture comprising unsaponifiable matter which might also comprise unsaponified saponifiable matter, typically esters of sterols or stanols and esters of fatty alcohols.
A typical composition of the unsaponifiable material obtained from black liquor soap by means of solvent extraction processes is as follows: Monoterpenes (&agr;-terpineol) 0.3%; Diterpenes (about 45 parts) 41.2%; Steroids (about 17 parts) 32.4%; Triterpenes (about five parts) 0.6%; Polyprenols 0.7% Wax alcohols (about ten constituents ) 6.1%; Stilbenes (about two parts) 5.7%; Lubricating oil 4.4% and minor parts 8.6%. Unsaponifiable matter obtained from saponified tall oil pitch usually contain the same components although in different proportions; in general, it contains less fatty alcohols. The composition of tall oil pitch is strongly dependent on the distillation equipment and operating conditions employed in the distillation of tall oil.
Skimmings may be used as fuel oil; its calorific value is a little lower than the half of fuel oil calorific value. It may also be transformed into tall oil by adding sulfuric acid and separating the oil from the aqueous phase. This oil is known as CTO (crude tall oil). Then, CTO is exposed to a series of vacuum distillations producing fatty acids (TOFA or tall oil fatty acids), which constitute one of the most valuable fractions of CTO; rosin acids (TORA or tall oil rosin acids); distillate tall oil (DTO), which has many uses; and pitch, the bottom of the distillation, which is used as fuel or as an ingredient for the preparation of asphaltic emulsions. Lately, the pitch has been considered as a convenient source of sterols because it contains between 7-20% of sterols either free or in esterified form.
The following are processes disclosed for obtaining sterols from neutral matter of black liquor soap skimmings or from tall oil pitch:
U.S. Pat. No. 2,499,430 to Christenson and Vogel teaches a liquid-liquid extraction process to recover sterols from saponified tall oil.
U.S. Pat. No. 2,528,025 to Whyte teaches a process for the isolating of sterols by means of crystallization from methyl cyanide solutions.
U.S. Pat. No. 2,530,809 teaches the crystallization of sterols from a solution of a lower alcohol or acetone.
U.S. Pat. No. 2,536,753 to Knol teaches the recovery of sterols by means of the formation of addition compounds with zinc chloride and then decomposing said compounds.
U.S. Pat. No. 2,568,202 to Hackmann and Overhoff teaches the process of recovery of sterols by forming addition products of sterols with metal salts under anhydrous conditions.
U.S. Pat. No. 2,573,265 to Folzenlagen and Lange teaches a process for separating sterols from unsaponifiable material, by means of first forming a solution in an oxygen-free liquid solvent then precipitating sterols with perchloric acid.
U.S. Pat. No. 2,573,891 to Christenson teaches the dissolution of a sterol concentrate and its partition in immiscible mixture of solvents followed by the recovery of a refinate rich in sterols.
U.S. Pat. No. 2,585,954 to Mattikov and Perlman teaches the recovering of sterols from phosphatidic material by a combined solvent extraction and crystallization process.
U.S. Pat. No. 2,697,503 to Christenson teaches a process of obtaining a concentrate of unsaponifiable matter of soybean oil and the obtainment of sterols thereof by means of solvent extraction followed by evaporation.
U.S. Pat. No. 2,715,639 to Albrecht and Herrlinger teaches the recovery of sterols from tall oil pitch by first saponifying said pitch, diluting with warm water and then cooling to precipitate sterols.
U.S. Pat. No. 2,729,656 to Berry and Miller teaches a process of recovering sterols by saponifying the sterol containing material, separating soaps and sterols with an solvent followed by crystallization.
U.S. Pat. No. 2,729,655 to Cunningham and Greiner teaches a process of recovering sterols by acidifying a saponification reaction mixture, esterifying fatty acids and recovering sterols from the esterification mixture.
U.S. Pat. No. 2,866,797 to Berry et al. teaches an improved process of isolating sterols from a solution of ethylene dichloride to which water and methanol is added to precipitate sterols.
U.S. Pat. No. 3,108,120 to Brown and Meng teaches the recovery of sterols and tocopherols from unsaponifiable matter by extracting with a selective solvent.
U.S. Pat. No. 3,691,211 to Julian teaches a process for preparing sterols from plant sources, especially tall oil pitch, by extraction in a water-alcohol-hydrocarbon mixture followed by saponification and subsequent recrystallization and leaching.
U.S. Pat. No. 4,044,031 to Johansson et al. teaches a process for the separation of sterols from mixtures of unsaponifiables obtained from crude soap skimming by extraction of a suitable solvent followed by crystallyzation.
U.S. Pat. No. 4,076,700 to Harada and Yamamoto teaches a process of recovering sterols from tall oil skimming soap by first dehydrating the mixture and evaporating from said mixture sterols in a thin film evaporator.
U.S. Pat. No. 4,153,622 to Koskenniska teaches the recovery of sterol from
Badio Barbara P.
Baker & McKenzie
Glade Thomas Francis Harting
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