The behavior of resin acids during tall oil distillation

The behavior of resin acids during tall oil distillation was studied by analyzing samples from six industrial-scale processes. The same artifact resin acids were formed in all processes. However, the proportion of artifact resin acids in tall oil rosins varied from 8.3 to 18.3% of the resin acids. The lowest values were found for two processes utilizing thin-film evaporators. The yield of resin acids in the tall oil rosin fraction varied from 62 to 80% of the resin acids in the crude tall oil feeds. Dehydroabietic acid was formed in all processes, the amount in rosin being 14-44% more than in the crude tall oil feed. Of the abietic acid, only 45-82% was recovered in the tall oil rosin fraction. The distribution of various resin acids and their reaction products during distillation was determined. Major resin acid impurities in tall oil fatty acids were 8,15-pimaradien-18-oic acid and 8,15-isoprimaradien-18-oic acid, both formed chiefly during distillation, and two secodehydroabietic acid isomers common in crude tall oils. The reactions of resin acids leading to new isomers or non-acidic products are discussed. Some results of this work were presented at the 173rd American Chemical Society Meeting, New Orleans, March 1977.     

Solvent extraction of fatty acids from natural oils with liquid water at elevated temperatures and pressures

The use of liquid water at elevated temperatures and pressures as an extractive solvent for separating mixtures of compounds which occur in natural oils has been studied. A southern pine tall oil and a distillate from the deodorization of soybean oil were extracted with liquid water at temperatures from 298 to 312°C and pressures between 103 and 121 bar. Results indicate that water can be used to extract fatty and resin acids from crude tall oil to obtain a product with a high acid content that produces less pitch during distillation. The process can also be used to extract fatty acids from vegetable oil deodorizer distillate.     

Tall oil fatty acids

About 1949, with the advent of effective fractional distillation, the tall oil industry came of age, and tall oil fatty acids (TOFA), generally any product containing 90% or more fatty acids and 10% or less of rosin, have grown in annual volume ever since, until they amount to 398.8 million pounds annual production in the U.S. in 1978. Crude tall oil is a byproduct of the Kraft process for producing wood pulp from pine wood. Crude tall oil is about 50% fatty acids and 40% rosin acids, the remainder unsaps and residues; actually, a national average recovery of about 1–2% of tall oil is obtained from wood. On a pulp basis, each ton of pulp affords 140–220 pounds black liquor soaps, which yields 70–110 pounds crude tall oil, yielding 30–50 pounds of TOFA. Separative and upgrading technology involves: (a) recovery of the tall oil; (b) acid refining; (c) fractionation of tall oil; and occasionally (d) conversion to derivatives. TOFA of good quality and color of Gardner 2 corresponds to above 97% fatty acids with the composition of 1.6% palmitic & stearic acid, 49.3% oleic acid, 45.1% linoleic acid, 1.1% miscellaneous acids, 1.2% rosin acids, and 1.7% unsaponifiables.     

Tall oil

Summary Tall oil processing is a relatively new and rapidly growing industry. Based on a stable supply of raw material from the kraft paper industry, it provides an important source of rosin and fatty acid products. The processes most generally employed in the United States are acid refining, distillation, and separation by fractional distillation. Tall oil refining techniques have advanced to the point where fatty acids substantially free from rosin acids and rosin substantially free from fatty acids are produced. With continued growth of the industry and further advances in tall oil technology, products of even greater refinement and wider utility may be expected in the not too distant future.     

Origin of bicyclic fatty acids in tall oil

It was shown that two bicyclic fatty acids present in Finnish tall oil were formed from (5Z, 9Z, 12Z)-5, 9, 12-octadecatrienoic acid, pinolenic acid (I). Under the alkaline conditions of sulfate pulping, pinolenic acid forms conjugated isomers which undergo Diels-Alder cyclization during the heating in the tall oil distillation. The cyclization products, here called cyclopinolenic acids, are bicyclic fatty acids and stereoisomers of 4-(5-pentyl-3a, 4,5,7a-tetrahydro-4-indanyl) butanoic acid (IV and V).     

Spectrophotometric analysis of tall oil rosin acids

Summary About half of the rosin acids in whole and distilled tall oil consist of abietic and neoabietic acids, as distinguished from hydroabietic acids, dehydroabietic acid, and the pimaric acids. In this respect the tall oil rosin acids are similar to those from gum or wood rosin. This was established by spectrophotometric analysis of the rosin acids from whole tall oil, double distilled tall oil, rosin acids crystallized from tall oil, and rosin acids separated from tall oil by fractional distillation. The rosin acids crystallized from tall oil contained the highest percentage of abietic acid, but the sum of abietic and neoabietic acids was only slightly higher. The rosin acids from acid refined tall oil contained appreciably less abietic and neoabietic acid than the others. Before spectrophotometric analysis the rosin acids were isolated from the tall oils in about 95% yield by cyclohexylamine precipitation.     

Gas chromatographic separation of diterpene acids on glass capillary columns of different polarity

Mixtures of resin acids from tall oil distillation products and from naturally occurring rosins (colophony) were separated on WCOT glass capillary columns coated with SE 30, FFAP, DEGS and BDS, and the resin acids were identified by gas chromatography-mass spectrometry (GC-MS). In contrast to previous investigations, the identified diterpene acids are characterized by Kovats index values. These retention values are correlated with the different polarity of the stationary phase. The advantages of columns coated with FFAP for the separation of crude and distilled tall oil and fatty acid samples are discussed. Dedicated to Prof. Dr. Erich Ziegler at his 70th birthday     

Capillary gas chromatography-mass spectrometry of resin acids in tall oil rosin

The resin acid composition of Finnish tall oil rosin was investigated by gas chromatography and mass spectrometry employing open tubular capillary columns. On a column coated with 1,4-butanediol succinate, 16 resin acids found in tall oil rosin samples were well resolved, and mass spectra could be recorded. All resin acids were confirmed to be of the pimaric and abietic types by gas chromatographymass spectrometry. Eight of the acids were not detected in the corresponding crude tall oils and evidently had been formed during the technical distillation process. The presence of 8,15-pimaradien-18-oic and 8,15-isopimaradien-18-oic acids in the rosin, but not in the crude tall oil, indicates that the pimaric type acids also undergo extensive isomerization during tall oil distillation. Additionally, three dihydroabietic acids and two acids with identical mass spectra, tentatively stereoisomers of 7,9(11)-abietadien-18-oic acid, were formed during the distillation process.     

A study of the influence of storing wood on the yield and quality of tall oil

In 12 weeks of storage time pine roundwood lost approximately 11% in tall oil yield, while for the same length of time purchased slabwood chips (pine) lost 64%. Most of the loss in yield occurred within six weeks. The purchased chips lost more tall oil yield in one week than the roundwood in 12 weeks. The loss in yield from the roundwood was due entirely to the loss in yield of fatty acids. The loss in yield in the purchased slabwood chips was due predominantly to the loss in yield in fatty acids; however, there was, in addition, a small loss in resin acids, and a very small loss in unsaponifiables. As for tall oil quality, by the end of 12 weeks of storage the acid number of tall oil from both roundwood and purchased chips had dropped below 160. In correlating the yield of tall oil from the wood extractions with the yield of tall oil from the black liquor from digester cooks, it appears that on the average about 80% to 88% of the extracted tall oil can be found in the black liquor.     

Identification of minor cyclic fatty acids in fractionated tall oil

The structure of several minor cyclic fatty acids present in Finnish tall oil fatty acids are elucidated by gas chromatography-mass spectrometry. The origin and mechanism of formation of these cyclic fatty acids are discussed. The cyclic fatty acids identified in tall oil fatty acids are: 4-(5-pentyl-3a,4,7,7a-tetrahydro-4-indanyl)butanoic acid,ω-(o-alkylphenyl)alkanoic acid, 2,6-dimethyl-9-(3-isopropylphenyl)-6-nonenoic acid, 4-(5-pentyl-4-indanyl)butanoic acid, and 4-(2-hexyl-1,2,4a,5,6,7,8,8a-octahydro-1-naphthyl)butanoic acid. In addition, three different branched or cyclic unsaturated C₁₉ fatty acids are reported to be present in tall oil.     

The fat acids of American tall oil

Summary The composition of the fat acids of six samples of American tall oil has been determined. They are all quite similar in fat acid composition. The average values were: linoleic acid 48%; oleic acid 45%; saturated acids 7%. There is present approximately 11% of conjugated linoleic acid, probably formed by the action of alkali and heat during the cooking of the pulp from which the tall oil was formed. Detailed fractional distillation of a sample of the methyl esters of the fat acids showed that the saturated acids are mostly palmitic, that there may be about 1% of palmitoleic, and that the conjugated linoleic acid present can be separated and concentrated by fractional distillation. Paper No. 65, Journal Series, Research Department, General Mills, Inc.     

Industrial Waste Materials as a Source of Sterols

The content of sterols and their derivatives have been examined in the following industrial waste materials: oily bleaching earth, volatiles from deodorization of oils, residue after distillation of tall oil, residue after distillation of crude animal and plant fatty acids. Amount of sterols directly occurring in such raw materials as low erucic and high erucic rapeseed oil and tall oil has also been stated. The quality constitution of sterols contained in those raw materials has been estimated. The profitability of getting sterols from those sources for the purposes of the cosmetic and pharmaceutical industries have been considered.     

Tall oil fatty acid marketing

Once considered a low cost by-product of crude tall oil fractionation, tall oil fatty acids are now being used for their own distinctive and specific properties in special applications. Consumption of tall oil fatty acids in protective coatings, soaps, and ore flotation has declined in recent years, however, usage in chemical intermediates has increased significantly in the past 10 years. These intermediates are dimer acids, oleic and linoleic acids, epoxidized esters, amidoamines, and diacids. Static tall oil production during the mid 1970s caused by changes in paper mill operations (i.e., continuous digestion, waste recycling, increased usage of chips and hard wood) has increased the demand for higher priced oleic acid and other unsaturated fatty acids.     

Production methods for the manufacture of crude tall oil and its subsequent processing

Summary The source of crude tall oil and methods to produce the oil have been described. These include acidulation of sulfate pulp, black liquor skimmings, and gravity settling as well as centrifugal means of separation to reduce the lignin content of the product. Subsequent processing of the crude tall oil into fractionated fatty acids and rosin has been outlined with suggestions for consideration in all stages of the distillation section of the plant.     

Production of biodiesel fuel from tall oil fatty acids via high temperature methanol reaction

Tall oil fatty acids are a byproduct of the paper industry and consist predominantly of free-fatty acids (FFAs). Although this feedstock is ideal for biodiesel production, there has been relatively little study of its conversion to biodiesel. Thus, the purpose of this study was to investigate the high temperature reaction of methanol with tall oil at subcritical and supercritical pressures to produce fatty acid methyl esters. This study investigates the effects of mixing, pressure, temperature, and methanol to oil molecular ratio in order to determine the potential use of tall oil as a biodiesel feedstock. In this work, tall oil fatty acids were successfully reacted with supercritical and subcritical methanol in a continuous tubular reactor, resulting in a reaction that is primarily temperature dependent. Conversions at subcritical pressures of 4.2 MPa and 6.6 MPa were 81% and 75%, respectively. Pressure seemed to have little correlation to conversion in both regimes, and conversions were comparable between the two. Additionally, it was found that tall oil fatty acids react well with methanol to give comparable conversions at the relatively low molecular flow ratio of 5:1 methanol to tall oil. Both of these observations suggest that hydrolyzed triglycerides or free fatty acid feedstocks would make the primary high temperature biodiesel reaction and the subsequent separation and purification operations less expensive than was previously believed.     

Fractional distillation

While practically all the fatty acids produced in the fatty acid industry are distilled products, these materials are all, at least to some degree, fractionated fatty acids. Rarely indeed are today’s fatty acids suited for any of the many applications to which they are put without the quality and homolog distribution improvements which only fractional distillation can guarantee. Thus, this separation is of vital importance within the fatty acid and derivative industries. Fractional distillation is industrially a practical separative method for: (a) 16:0 and 18:0 fatty acids, such as those derived from hydrogenated fats and oils like tallow, soybean, cottonseed soapstocks, palm oil and others; (b) 18:0, 20:0, 22:0, and 24:0 fatty acids from hydrogenated fish oils or high erucic rapeseed oil; and (c) 8:0, 10:0, 12:0, and 14:0 fatty acids from the hydrogenated fatty acids from the lauric oils group (coconut, palm kernel, babassu, etc.). While theoretically possible under idealized conditions in the laboratory, it is not practical to separate palmitic, oleic, heptadecanoic, and stearic acids by means of fractional distillation     

Untersuchungen über die Modifizierung des finnischen Milchfettes

Investigations on the Modification of Finnish Milk-Fat The author investigated the fatty acid composition of Finnish milk-fat and the possibilities for the modification of the latter. The influence of the different feeds at various seasons of the year and the action of feeding fatty acid distillate from tall oil were determined. Furthermore the composition of Finnish milk-fat was determined by molecular distillation, crystallization from acetone and interesterification. Mainly gas chromatography was employed for determining fatty acid composition.     

Tallöl-Fraktionierung als Beispiel der Optimierung konventioneller Füllkörperkolonnen

Fractionation of Tall Oil as an Example of Optimization of Conventional Packed Columns The present communication records a simple calculation for optimization of packed columns in an example of layout of columns for fractional distillation of crude tall oil into the main products, i.e. fatty acids and resin acids. This calculation requires, apart from knowledge on the temperatures stability of the material, only the HETP value, which is the height of chosen packing material equivalent to one theoretical plate. An arrangement of three columns is necessary for complete separation of crude tall oil in continuous manner. In the example shown, calculation of the first column for a capacity of 20 000 t per year is given.     

Purification of specific structured lipids by distillation: Effects on acyl migration

The cause and effects of acyl migration during the purification of specific structured lipids by distillation were studied in a conventional batch deodorizer with stripping steam. The mixture of specific structured lipids produced by lipase-catalyzed acidolysis between rapeseed oil and capric acid contained a large amount of free fatty acids and a small amount of partial acylglycerols besides triacylglycerols. Therefore, the effect of steam, free fatty acids, diacylglycerols, and monoacyl-glycerols on acyl migration was studied in a palm oil midfraction model. The results showed that all these factors influenced the rate of acyl migration, and their combinations made the effect more severe. However, diacylglycerols were found to be the main reason for acyl migration. In the distillation of the specific structured lipid product mixture, distillation temperature and time were the main factors to determine the degree of acyl migration and the extent of separation of free fatty acids. The results indicate that more efficient separation technology should be used to improve the quality of the purified structured lipids. In order to reduce the distillation temperature, vacuum should be made as low as possible with more effective pumps. To reduce the distillation time, thin-film principle in a packed column should be used, or other more efficient distillation techniques such as molecular distillation or short-path distillation should be exploited.     

Chemical evaluation of egyptian citrus seeds as potential sources of vegetable oils

Seeds of the citrus fruits orange, mandarin, lime and grapefruit were analyzed. Petroleum ether-extracted oils of such seeds amounted to more than 40% of each. Physical and chemical properties of the extracted oils are presented. Samples of the extracted oils were saponified and the unsaponifiables and fatty acid fractions isolated. The isolated unsaponifiables and fatty acids were analyzed by GLC. GLC analysis of the unsaponifiables revealed compositional patterns differ-ent in number, type and relative concentration of fractions according to type of citrus seed oil, depending on the solvent system used for oil extraction and unsaponifiable matter isolation. The compositional patterns of the unsaponifiables were similar to that of cottonseed oil. Mandarin and grapefruit oils are free of cholesterol. The data demonstrate that the fatty acid compositional patterns of the oils differ; Mandarin seed oil contains the largest number of fatty acids, and grapefruit seed oil contains the lowest. The total amounts of volatile fatty acids in these oils are generally higher than those of other edible oils. Lime seed oil is similar, in the degree of unsaturation, to soybean oil. The orange oil pattern is similar to cottonseed oil. The amount of total essential fatty acids in lime seed oil is the highest of the oils studied.