Crude tall oil

Crude tall oil Crude tall oil (CTO) Cruformate [299-86-5] Cruise missiles Crumb rubber Crushing... 

Tall oil fatty acids (TOFA) consist primarily of oleic andlinoleic acids and are obtained by the distillation of crude tall oil. Crude tall oil, a by-product of the kraft pulping process, is a mixture of fatty acids, rosin acids, and unsaponiftables (1). These components are separated from one another by a series of distillations (2). Several grades of TOFA are available depending on rosin, unsap oniftable content, color, and color stabiUty. Typical compositions of tall oil fatty acid products are shown in Table 1 (see Tall oil). 

Tall oil rosin is obtained from crude tall oil obtained from the Kraft (sulphate) pulping of various coniferous trees in the paper manufacturing industry. During the Kraft pulping process the fatty acids and the resin acids from the coniferous wood are saponified by the alkaline medium. On concentration of the resulting pulping liquor, the sodium soap of these mixed acids rises to the surface from where they are skimmed out. By acidification of this material with sulphuric acid, the crude tall oil is obtained. Fractional steam distillation of the crude tall oil allows the separation of the tall oil fatty acids and the tall oil rosins [21]. 

Hydrotreating has been proposed by Arbokem Inc. in Canada as a means of converting Grade Tall Oil into biofuels and fuel additives. However, this process is a hydrogenation process which produces hydrocarbons rather than biodiesel. Recently a process for making biodiesel from crude tall oil has been proposed. It relies on the use of an acid catalysts or of an acyl halide for the esterification reaction, but no information is given on the properties of this fuel, particularly concerning the oxidative stability. 

During the kraft pulping process, the first step in making hundreds of paper products, crude tall oil is obtained from the alkaline material by acidifying it with sulfuric acid. The crude tall oil is then converted through dehydration, dry distillation, and finally the fractionation of the vaporized tall oil compounds. Fatty acids, rosin acids, and neutral materials make up tall oil. 

Hydrotreating has been proposed by Arbokem in Canada [47] as a means of converting crude tall oil into biofuels and fuel additives. However, this process is a hydrogenation process that produces hydrocarbons rather than biodiesel. 

Tall oil rosin is a by-product of paper manufacturing. Raw wood chips are digested under heat and pressure with a mixture of sodium hydroxide and sodium sulfide. Soluble sodium salts of lignin, rosin, and fatty acids are formed, which are removed from the wood pulp as a dark solution. The soaps of the rosin and fatty acids float to the top of the mixture, where they are skimmed off and treated with sulfuric acid to free the rosin and fatty acids. This mixture, known as crude tall oil (CTO), is refined further to remove color and odor bodies fractional distillation separates the tall oil rosin acids from the fatty acids (see Tall oil). 

Schlack [2] and Castan [3,4] are credited with the earliest U.S. patents describing epoxy resin technology. Greenlee [5] further emphasized the use of bisphenols and their reaction with epichlorohydrin to yield diepoxides capable of reaction with crude tall oil resin acids to yield resins useful for coatings. The use of diepoxide resins that are cured with amines was reported by Whittier and Lawn [6] in a U.S. patent in 1956. 

Black Liquor Soap Acidulation. Only two-thirds of a typical black liquor soap consists of the sodium salts of fatty acids and resin acids (rosin). These acids are layered in a liquid crystal fashion. In between these layers is black liquor at the concentration of the soap skimmer, with various impurities, such as sodium carbonate, sodium sulfide, sodium sulfate, sodium hydroxide, sodium lignate, and calcium salts. This makes up the remaining one-third of the soap. Crude tall oil is generated by acidifying the black liquor soap with 30% sulfuric acid to a pH of 3. This is usually done in a vessel at 95°C with 20—30 minutes of vigorous agitation. Caution should be taken to scrub the hydrogen sulfide from the exhaust gas. 

The crude tall oil fatty acids obtained from the rosin column usually contain about 5% rosin because the boiling points of the heavier fatty acids and the lighter resin acids overlap. By adding the intermediate fraction to the fatty acid, rosin does not have to be redistilled. 

Solvent extraction has found application for many years in the coal tar industry. Extraction of phenols from coal-tar distillates by washing with caustic soda solution can be considered such a process. In the isomer separation, a process for separation of m- and p-crcsol by dissociation extraction has been reported. Work is in progress in several parts of the world to use solvent extraction for the direct manufacture of chemicals from coal. Crude tall oil is a byproduct of pulp mills. It is refined by solvent extraction using propane or furfural. 

Fig. 10-3. Main distillates obtained from crude tall oil after acidification.

The spent black liquor from the kraft pulping of pines contains the less volatile products of the wood resin in the form of sodium salts or soaps. The liquor first is concentrated in multiple-effect evaporators, and then the concentrate is sent to settling tanks. The soaps rise to the surface, are skimmed off, and then are acidified with sulfurous or sulfuric acid. The crude tall oil rises to the top and is mechanically separated. Crude tall oil from southern pines contains 40-60 percent resin acids and 40-55 percent fatty acids with 5-10 percent neutral substances. These components are separated by fractional distillation under vacuum. 

One metric ton of crude tall oil yields about 350 kg of rosin, 300 kg of fatty acids, and 300 kg of head and pitch fractions. For each metric ton of pulp produced, northern pines yield about 50 kg of tall oil, and the southern pines yield about 125 kg. The U.S. capacity for fractional distillation of tall oil is nearly one million metric tons per year. 

The neutral or unsaponifiable materials present in tall oil include anhydrides, pheno-lics, diterpene aldehydes and alcohols, stil-benes, and steroids. In the neutral fraction of southern pine tall oil soap, 80 compounds have been identified. They include 25.1 percent sistosterol and a total of 32.4 percent steroids. The sistosterol content of crude tall oil is 2-3 percent and is the main component of the neutral fraction. 

Pine-Based Chemicals Crude Tall Oil Fractionation... 

Production Of Diesel Fuel Additives From The Rosin Acid Fraction Of Crude Tall Oil... 

Tall oil fulfils all of these requirements. Tall oil is a natural product of pine trees that is isolated by means of the Kraft pulping process. It is composed of the ether extractable, non-lignin, non-cellulosic portion of the pine tree, and it must be fractionated via steam-vacuum distillation for commercial use. Fractionation of one metric ton of crude tall oil produces about 350 kg of rosin acids, 300 kg of fatty acids and 330 kg of distillated tall oil, head and pitch. The economic value of tall oil is primarily derived from its fatty acid fraction. 

Tall oil rosin production has recently been driven by demand for its co-product, tall oil fatty acid. United States production of tall oil rosin in 1994 was 265,000 metric tons, exceeding consumption by nearly 50,000 metric tons. Therefore, the rosin acid fraction of crude tall oil is an under-used byproduct in abundant supply, with attractive characteristics as a precursor to high value chemicals. Two components, abietic acid and dehydroabietic acid, con rise about 70% of the rosin acid fraction of tall oil. Therefore, it is a relatively single mixture, which is also a beneficial characteristic for its use as a feedstock. 

This work, however, does not deal with crude tall oil but with the under-used portion of fractionated tall oil. the rosin acids, wdiich, as we mentioned before, show some advantages over crude tall oil. To our knowledge, this is the first time that the focus is on this firactton, although the work of Schuller s group provides a relevant basis for c q)loration... 

Sharma, R.K, and Bakhshi, N.N. Catalytic Conversion of Crude Tall Oil to Fuels and Chemicals over HZSM-5 Effect of Co-feeding Steam. Fuel Process. Techno . 27, 113-130, 1991. 

Pamak [Aqualon]. TM for various tall oil products including a series of tall oil fatty acids and distilled tall oils containing varying percentages of rosin acids. Pamak TP and WTP are residues from fractionation of crude tall oil in the manufacture of tall oil fatty acids. 

Crude Tall Oil Recovery, Tech. Sect. Proc., 47th Annu. Meet. Can. Pulp and Paper Assoc., Montreal, 1961. 

A complex system is one containing so many components that they cannot be separated into discreet pure components by the distillation process. An example of such a system is naturally occurring petroleum, which contains hundreds of chemical constituents. Crude tall oil from paper pulping is another example of a complex system. 

Crude tall oil is a mixture of fatty acids, resin acids, and neutrals (i.e., no carboxylic acid functionality). The background section relates that neutrals interfere with the separation of the fatty acids from the resin acids and in industrial practice the neutrals are removed by molecul distillation. However, it is difficult to separate the neutrals from the other components because of vapor pressure similarity considerations. Tall oil soap, the precursor to crude tall oil, is a pasty emulsion of the neutrals and the sodium salts of the fatty and resin acids. The patent states that it is possible to extract neutrals from the soap with a liquid hydrocarbon solvent, but the prior art discussion relates that subsequent liquid hydrocarbon solvent recovery steps are relatively difficult. The neutrals can be separated from the soaps by a hydrocarbon solvent, incidentally, because the neutrals are lipophiles whereas the soaps are ionic and do not dissolve in the hydrocarbon. Similarly the neutrals will dissolve in a supercritical fluid like ethylene, or propane, or the chlorofluorocarbons, and the use of these gases in the supercritical state is the invention. Like the case of liquid hydrocarbon solvents, the ionic soap compounds will not dissolve in the supercritical gases. CO2 is specifically not listed among the gases, and we shall discuss the case of CO2 extraction of the emulsion later which is the subject of the next patent. 

Lawson, N.E. and G. I. Amer, Acidulation and recovery of crude tall oil from tall... 

Returning now to the patent, the invendon taught is the contacting of crude tall oil soaps (a moist mixture of neutrals and sodium salts of fatty and resin acids) with CO2. The CO2 converts the salts to free fatty and resin acids which then dissolve in the CO2 (but probably so are some of the neutrals). One example describes a laboratory test that reports that from a charge of 9.65 g tall oil soap five fractions were extracted with supercritical CO2. The first fraction contained 88% resin + fatty acids, and the fifth fraction contained 72% resin. 

Collectors are used to enhance the attachment of the particle to be floated to the gas bubble. These are usually the unsaturated 18-carbon fatty acids, oleic and linoleic acids obtained from the distillation of crude tall oil and used in a mixture of about equal amounts. Hercules Trade Names for combinations of these two are Pamak and Pamolyn. 

The rapid growth of sulfate pulping in the South in the 1940s and 1950s led to the birth of the third type of naval stores in this country, the tall oil naval stores. In the tall oil naval store operation, the oleoresinous materials in the trees are recovered in the pulping process in the forms of sulfate turpentine and crude tall oil. The crude tall oil, comprising rosin and fatty acid, can... 

Crude tall oil is a mixture of fatty acids (45%), rosin acids (42%) and unsaponifiables (triterpenes 13%). The characterization of the fatty and resin acids has been described by a number of workers including Holmbom (1977, 1978). The resin acids... 

Most of the crude tall oil is fractionally distilled to separate the resin and fatty acids which are present in approximately equal amounts. The specifications for different grades of tall oil fatty acids are given above. 

To illustrate another component of the forest products industry it may be instructive to take a brief look at the pine chemicals industry. The pine chemicals industry is not a new industry, but it is a very small portion of what is now known as the specialty chemicals industry, despite the fact that pine chemicals have been in active use for longer than the modern chemical industry era that arose in the early part of the 20th century. The pine chemicals industry has been extracting useful products such as turpentine and other simple materials for literally hundreds of years. With the rise of the pulp and paper industry, chemicals have in the majority been extracted from two waste streams crude tall oil and crude sulfate turpentine. Crude tall oil can be further separated into a fatty acid fraction, a tall oil fraction, a tail oil rosin fraction, and a tall oil pitch fraction. The crude sulfate fraction is separated into a variety of terpene monomers that can be further transformed into a variety of terpene resins. AH of these streams can be used as raw materials for coatings, various oil applications, surfactants, adhesives, inks, etc. [50]. 

Tall oil, acid refined n. Product obtained by treating crude tall oil in solvent solution with sulfuric acid under controlled conditions to remove dark color bodies and odoriferous materials. Removal of the solvent yields a product with lighter color and higher viscosity than crude tall oil with approximately the same fatty acids-to-rosin ratio. 

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