US2451377A

US2451377A - Hydrogenation of tall oil

Info

Publication number: US2451377A
Application number: US594605A
Authority: US
Inventors: Bliss Harding; William C Sussky
Original assignee: Dictaphone Corp
Current assignee: Dictaphone Corp
Priority date: 1945-05-18
Filing date: 1945-05-18
Publication date: 1948-10-12
Anticipated expiration: 1965-10-12

Description

Patented a. 12, 1948 HYDBOGENATION 0F TALL 01L Harding Bliss, Hamden,

Conn., and WillianfC. Sussky, Little Rock, Aria,

assignors to Dictaphone Corporation, New York, N. Y., a corporation of New York No Drawing. Application May 18, 1945,

. Serial No. 594,605

This invention relates to the production of relatively hard, fatty materials from tall oil and, more particularly, to an improved hydrogenation and extraction process for obtaining from tall oil a hard, fatty product such as stearic acid.

In the manufacture of paper pulp'by digestion of wood with alkaline liquors, and particularly in connection with the so-called sulphate process. a dark oily material known as tall oil is produced as a by-product. Tall oil consists chiefly of a mixture of roughly equal parts of unsaturated fatty acids and resin acids together with minor proportions of other components such as sterols. Because of its fatty acid content tall oil is a possible source of stearic acid and other hard, fatty materials that may be obtained by hydrogenation of unsaturated fatty acids such as those contained in tall oil.

Many processes have'been' proposed for treating tall oil in such manner as to recover a commercially useful hard, fatty material. One group of previously proposed methods is directed toward separating or isolating the fatty acidcontent of the crude tall oil and then hydrogenating the separated unsaturated fatty acids. Methods previously proposed for separation of the fatty acids include fractional crystallization, fractional distillation at reduced pressures and/or steam distillation, and selective esterification. None of these processes has so far proven satisfactory for commercial operation.

Another group of previously proposed methods is directed to preliminary purification of the tall oil followed by hydrogenation of the tall oil without any preliminary attempt to separate the fatty acids and resin acids in the crude tall oil. .In some cases elaborate pre-treatment methods have been suggested with a view toward obtaining a material that may be hydrogenated to give a high quality product but these methods have proven to be either inadequate or excessively expensive when an attempt is made to carry them out on a commercial scale.

It is therefore an object of the, present invention to provide an improved process for producing a hard, fatty product from tall oil. It is another object of the invention to provide an improved method for hydrogenating crude tall 011 which has undergone no previous refining steps. It is a further object of the invention to provide a process wherein hydrogenation is used in conjunction with a selective solvent to produce a fatty product of relatively high melt-- ing point. Other objects of the invention will '7 Chime. (Cl. 260-915) be in part obvious and in part pointed out hereinafter.

The present method is based upon the discovery that 1,4-dioxane exerts a selective solvent action on the products of, the hydrogenation of tall 011 and that its use makes possible a more effective separation of such products. The dioxane may be added to the tall oil before it is hydrogenated or alternatively the tall oil may be first hydrogenated and the hard fatty products separated out by means of dloxane. The use of dioxane is of particular advantage in cases where it is desired to hydrogenate crude tall oil directly without any preliminary purification.

In accordance with one embodiment of the present method a quantity of dioxane, preferably between about one-third and two parts by weight of solvent per part of tall oil is mixed with crude tall oil and the mixture hydrogenated at a relatively high temperature and pressure in the presence of a finely divided, highly active catalyst. It has been found that by carrying out the hydrogenation of the crude tall oil at a relatively high temperature and pressure in the presence of such an active catalyst a fatty product of relatively high melting point may be obtained. The reaction pressure during hydrogenation is preferably maintained at between three hundred and two thousand pounds per square inch and the reaction temperature is desirably maintained between about 250 F. and 475 F. The catalyst used may comprise finely divided nickel or a mixture of copper and nickel suspended in a suitable medium such as cottonseed oil or fish oil. It has been further found that an improved product may be obtained by carrying out the hydrogenation reaction in a plurality of steps. Crude tall oil is hydrogenated under the conditions indicated above and the reaction conditions are maintained until the rate of reaction falls below a predetermined minimum value. A further quantity of catalyst is then added to the reaction mixture and hydrogenation continued under the same or similar operating conditions for a further period of time. It has been found that the degree of saturation of the product may be substantially increased by a second hydrogenation-step of this character. Further hydrogenation steps still further increase the satura tion of the product, but ordinarily it will not be economical to use more than two hydrogenation steps.

In carrying out the hydrogenation reaction the mixture in tall oil and catalyst is preferably heated during the initial stages of the reaction" i 3 to a temperature in the lower portion of the above-stated range, 1. e. 250' F. to 325 F. As the reaction proceeds the temperature is raised and reaches a maximum at or near the end of the reaction. The maximum temperature attained should desirably 'fall in the range of 350 F. to 475 F.

The quantity of catalyst used may vary over a considerable range depending upon the type of catalyst used and to some extent upon the scale of operations. Where small quantities of tall I oil are being hydrogenated a somewhat larger percentage of catalyst should be used. Typical proportions of catalyst are given in the following specific examples. In general it has been found that the catalyst should be present to the extent of about 0.05% to 5% by weight of the mixture.

Owing to the presence of dioxane in the reaction mixture, the product of the hydrogenation reaction separates into two phases, a highly hydrogenated solid waxy phase and an oily liquid phase containing the .resin acids and other unsaturated acids. Thus, by the use of this solvent in the proper quantities, a fatty product may be more easily obtained which contains a relatively high proportion of saturated fatty acids. As pointed out above the preferred proportions of dioxane lie between about one-third and twoparts by weight of solvent per part of crude tall oil. If the solvent added exceeds about two parts per part of crude tall oil, there will usually be no appreciable phase separation after hydrogenation. As the proportion of solvent is reduced the amount of the solid waxy phase that separates out increases, but its purity decreases correspondingly. It was found that when the solvent ratio was reduced to one-third part of solvent per part of tall oil or less both phases were solid and difficult to handle. Moreover, the waxy phase was of such low purity as to make the use of solvent of doubtful benefit. However, within most of the stated rangee, i. e. onethird to two parts of solvent per part of tall oil, there is sharply defined separation of the waxy phase and this waxy phase is about 50% to 80% hydrogenated.

In order to point out more fully the nature of the present invention the following example is given of a preferred mode of carrying out the invention: 450 grams of crude tall oil having an iodine value of 258 were mixed with 450 grams of 1,4-dioxane and 11.2 grams of a catalyst. (The iodine values given in the present example were determined by the. method described in Ind. Eng. Chem., Anal. Ed, 16, 371 [1944]). The catalyst used comprised a suspension of finely divided nickel particles in fish oil and contained about 24% nickel and 76% of the fish oil. It is sold commercially by the Rufert Chemical Company and is identified by the manufacturer as No. 1771.

The mixture of crude tall oil, catalyst and dioxane was charged into a pressure vessel and hydrogenated at a pressure of about 1000 pounds per square inch gauge and a maximum temperature of 390 F. The temperature was raised over a period of time from room temperature to the stated maximum of 390 F. The hydrogenation was continued for .a ,periodof 136 minutes..

After removal from the pressure vessel and 6 :12" cooling the reaction products separated into two phases, a solid phase and a liquid phase. The solid phase was cream-colored and waxy whereas the liquid phase was black and somewhat less viscous than the material originally charged to the reaction vessel. The two phases were separated and the solvent dioxaneremoved by distillation. Upon analysis it was found that the waxy solid material of the solid phase had an iodine value of 138 indicating that it was 46.5% hydrogenated. The titer of the solid was 52.4 C. The liquid phase, on the other hand, had'an iodine value of 228, a titer of 42.4 C. and was only 11.6% hydrogenated. It is therefore apparent that hydrogenation in the "presence of dioxane is accompanied by a separation of the more hydrogenated harder phase which is relatively rich in stearic acid.

The selective solvent action of the dioxane is not dependent upon its presence in the hydrogenation step, that is to say, a hydrogenated crude tall oil may after the hydrogenation step be mixed with suitable quantities of dioxane to give the desired phase separation. Thus, the hydrogenation of the crude tall oil, or even of a refined tall oil may be carried out under the conditions described above, and the hydrogenated product mixed with dioxane to give a separation of a solid, waxy phase containing a relatively high proportion of saturated fatty acids such as stearic acid.

From the foregoing description it is apparent that the present invention provides an effective method of hydrogenating crude tall oil to yield a hard fatty product containing a relatively large proportion of saturated fatty acids. The crude tall oil is used directly and no expensive and elaborate pre-treatment process is required. The use of dioxane as a selective solvent produces a sharp separation between the saturated fatty acids and the unsaturated fatty and resin acids, thus giving a relatively high yield of the desirable hard fatty product. If desired, the hydrogenation may be carried out in a plurality of steps to produce even higher yields of the fatty acids.

Since the present invention may have many embodiments and since many changes may be made in the embodiments described above, it is to be understood that the foregoing description is to be interpreted as illustrative only and not in a limiting sense.

We claim:

1. A method of producing a. hard, fatty product from tall oil which comprises forming a mixture of tall oil and 1,4-dioxane containing from 0.3 to 2.0 parts of dioxane by weight per part of tall oil, hydrogenating the mixture in the presence of a finely divided metal catalyst at an elevated temperature and pressure, cooling the and tall oil, hydrogenating said mixture in the presence of afinely divided metal catalyst at an elevated temperature and pressure, cooling the resulting product to cause said product to separate into a resin-containing liquid phase and a fatty solid phase, and separating said fatty solid from said resin-containing liquid.

3. A method of producing a hard, fatty product from tall oil which comprises hydrogenating tall oil oin the presence of a finely divided metal catalyst at an elevated temperature "and pressure, cooling the resulting product, mixing said product with an approximately equal quantity of 1,4-dioxane to cause said product to separate into a resin-containing liquid phase and a fatty 5 solid phase and separating said fatty solid from said resin-containing liquid.

4. A method of producing a hard, fatty product from tall 011 which comprises forming a mixture of tall oil and 1,4-dioxane containing from 0.3 to 2.0 parts by weight of dioxane per part by weight of tall oil, hydrogenating said mixture in the presence of a finely divided metal catalyst at a pressure between 300 and 2000 pounds per square inch, maintaining the temperature of the mixture during hydrogenation between 250 F. and 475 F., cooling the reaction product to cause the product to separate into a resin-containing liquid phase and a fatty solid phase, and separating said fatty solid from said resin-containing liquid.

5. A method of producing a hard, fatty product from tall oil which comprises forming a mixture of tall 011 and 1,4-dioxane containing from 0.3 to 2.0 parts by weight of dioxane per part by weight of tall oil, hydrogenating said mixture in the presence of a finely divided metal catalyst at a pressure between 300 and 2000 pounds per square inch, raising the temperature of the mixture during hydrogenation to between 350 F. and

475 F., cooling the reaction product to cause the product to separate into a resin-containing liquid phase and a fatty solid phase, and separating said fatty solid from said resin-containing liquid. 6. In a method of producing a hard, fatty prodproximately equal quantity of dioxane to cause a The following references are of record in 6 a uct from tall oil by hydrogenating said tall oil in the presence'of a catalyst at an elevated temperature and pressure to form a hydrogenated tall oil from which said fatty product can be recovered, the step of mixing with said tall 011 from .3 to to 2.0 parts by weight of dioxane per part by weight of tall oil to cause separation of said fatty product from said hydrogenated tail oil. 7 In a method of producing a hard, fatty product from tall oil by hydrogenating said tall oil in the presence of a catalyst at an elevated temperature and pressure to form a hydrogenated tall oil from which said fatty product can be recovered, the step of mixing with said tall oil an apseparation of said fatty product from said hydrogenated tall oil.

HARDING BLISS, WILLIAM C. SUSSKY.

REFERENCES CITED file of this patent: V

UNITED STATES PATENTS Number the