US2123342A - Hydrogenation of fatty oils - Google Patents

Description

T= mmed ,Jul? 2 1938. 7

w ortto M, otltialne t.

more particularly to the :hydrogenationofvege- 1 table oils containing glycerides or esters-"oi sat- 5 urated and unsaturated fattyacids. i

and other esters of the unsaturatedfatty acids are capable of addingonhydrogenattheir points or unsaturation or ethylene linkages 1 whereby a they beconiej more, or 1ess-- saturated depending upon the "amount or hydrogen Y added. The

non under well-known standard conditions;

Hydrogenation" of fatty bodies, such as vege pletely saturated acids; which causes the w consistencyoi! the fattyoils toiprogressively approach fthat whichis desired. it i j The-mostunsaturated fatty acids presentdn 1 "combination as esters in thewfatty oils have in general, a tendency to become changed to acids 1illustrate*this, we may consider linseed 011195 a i good example, since it contains in its composition fatty acids or four differentidegrees of saturation as follows, the analysis shown being representative o'fan average. sample: i 4 i i Percent I a Iiinolenicacid with three bonds of;un saturatlon i 1 33.1

nolic acid with two bonds of unsaturatiom 48.4 l0leiciacid with one bond of unsaturatlonrr 1 5,0 5 Saturated acids'with no bonds of unsatura tion... i i WhenY'anoiliof the above composition is catalytically hydrogenated, employing fthe co'rnmonly usedlmeans and methodsf the linolenic acid tends to absorb the hydrogen in preference i o the other unsaturated acidsfi'. e., linolic and oleic, thereby being changedinto theacidof the vnext degreeof' saturation, which is linolic. When v j acm so formed and the linolic acid originally presvamountof hydrogenfwhich the zfatty material absorbs is directly proportional to the .drop in the percent by weightbf iodine capable of com hining with the remainingfbon'ds of wunsaturaable oils, is usually accomplished atftelevated itrated fatty acids present as glycerldes or esters are changed tothe corresponding and more comof the next degree of i saturation before those in turn commence to combine with hydrogen. n i To i mostof the llnolenichas changedgthe linolic lfia zaa iz i n m oqnnarion or FATTY oILS 1 PatersomChestnut'Hill, ver Brothei-s Company, a corporation,

Ph -Em om n No pi-swine. Application OctoBer 10, 19 4 I v SeriaLNo. 44,392 i w H in n T bia 4G 1,

i 'Ihis invention relates to the 1 treatment of or exit in the-oil contlnue cadddon hydrogensto become oleic-acidwhich possesses only one unsaturation, which, in turn'proceeds to add on hydrogen to, become fully saturated when 'most of the linolic acid has changed. a i v i v i 5 Although, there this tendency? :toward pref erential hydrogenation of the more, unsaturated bodies, in actual practicethe hydrogenation does not occur intheabovefldescribed ideal stepwise i manner. i This :is believed to: be due largely to certain characteristics of the catalyst andhydrogen gas that arecommonly used the effects of which modify; and in many casesbsu bstantially eliminate. this general tendency toward preferential hydrogenation. The it desired characteristics of thehydrogengas, are disclosed in ,my Joint application Serial No. 723,838, filed May 4,

1934. "I'hedesiredtype of catalyst forms an important part ofthe subject matter of i the present inventionwaswill be apparent from the description to follow. i

One of the usual methodsof preparingniclrel hydrogenation catalystsjis to precipitate a readilyreducible salt ofnickel; such as thegcarbonates, hydroxides,etc., from a solutionof commerclal -nickelfls ulphate. When prepared by this ash but contains alsovaryingamounts ofabsorbed sulphates, depending, on the thorough- :ness with which the precipitate is washed. These :method thecatalyst contains not only the substances other than nickel derived from the nickel saltand the precipitant, e. g., commercial soda sulphates are subsequently reduced to sulphides and it liscommon to find 1%-2% of, sulphide of nickel in ordinarycatalysts. i

By a number: of tests, which I have performed,

I have found that the presence of nickel sulphide is undesirablesince it accelerates the fnormation sulphur, silicon, carbommanganese, arsenic antimony, bismuth, zinc, phosphorus, and traces of impurities not usually found by ordinary,

chemical analysis. I havefound that some of ,these substances have deleterious efiects upon the selective properties \of the hydrogenation ;catalyst and thereby prevent the desiredstepwise hydrogenation a Under theusual hydrogenating conditions employing these ordinary catalysts there is pracf tically always a jcertain amount of, the more comypletely saturated acids formed before the highly unsaturated acids have been' eliminated. How n ever, from the standpoint oi the final edible prodw it is ofextreme importance that the con-.

ditions of hydrogenation be. such that the oil absorbs the hydrogen in as nearly as possible the ideal preferential manner. as will be shown below.

In the manufacture of edible fats from hydrogenised'oils, it is essential that the above mentioned more highly unsaturated acids, e. g., linolenic and linolic. be hydrogenated as completely as s'inoe it lathe glycerides of these acids that are one to oxidation and accelerate rancid- I ity in thefat. For many'years-attempts have been made to obtain the idealhydrogenation,

by hydrogenating at comparatively high urea, since thelatter tend-to suppress the formation of fully saturatedfacids and thereby tend to prevent the'product' from becoming un duly hard before a sumcient degree of hydrogena- 7 tion of the highly unsaturatedacids is attained.

' Another attempt toprodiice this desirable result. consists in increasing theamount of catalyst used for eiIecting hydrogenationJ Unfortunately, the

of theaerelatively hightemperatures and etcesaive'amounts of-catalysts; although bene-' new from the standpoint of reducing saturation .of the' higher moiecular'weilht 1 1 in extremely deleterious effect 'inotherrespects when the ordinary types of catalyst are employed, particularly in that-the formation of hard isomeridea of acid -iaincreased. The latter render the product hard and brittle before it is sufliciently to insure its-keeping qualities: v 'lhe'exact compoaition'of these'isomerides of oleic acid.'foollectively-calied iso-oleic acid, is still I uncertain. It'ia believed, however, that their formation' is caused by ashifting of the double 'bond'in thecarbon chainlof the molecule and also by stereoisornerism' ofoleic' acid to elaidlc acid.

Hydrogenated vegetable oils. containing large amounts of iso-oleic acid make poor shortenings, being brittle and non-'plastic,with resultant inferiorbakingpropertiea. As has been indicated,

1 the amount of h K limited byemploying-reduced amounts of catalyst iso oleic acid' formed. may be and low hydrogenating temperatures, but these conditionsfhave shown to give ..mediocre oelectivity'of hydrogenation with the consequent formation of undesirably large amounts. of the Y normal saturated, acids ofhigh melting point. Theshortening resulting from oils so processed oannotbe-flnishedsatisfactorily to give the most desirable characteristics and also is dimcult to The suppress the formation of large amounts of the use'of high temperatures tends.to

saturated fatty substances. Thus, although there may have been some advantage in the use of higher temperatures, the adverse eiIect of such in increasing the formationof the predominates and the final result is a "product having very poor characteristics.

Untilthe'present' invention, it has been found necessary to effect a compromise with regard to thehydrogenation conditionsused. The usual result was the production 'of a fat containing considerable amounts of 'overly'hard components one fso incompletely saturated with hydrogenthat it did not have good keeping .One object of my inventionis to provide a a method and, means for producing an improved edible by th'e hydrogenatio'n of vegetable *Anotherobiect of m'yffinvention is to provide a method for producing' improved edible fats from vegetable by selectively l'i'ydrogenating the'oil amass:

in the presence of a hydrogenation catalyst of such a nature that the highly unsaturated fatty acids and glycerides originally present in the oil are sufllciently saturated to render the final hydrogenated product stable against rancidity and oxidation, and the formation of undesirable solid saturated and'unsaturated fatty acids and glyceridm is so minimized that the final product will not be excessi el hard. 1 I

A furtherobject is to provide a selective hydrogenation catalyst free from sulfates and sulfides and other components that normally adversely affect the selective characteristics of the catalyst. In accordance with my invention I have discovered that the catalyst and particularly some of its commonly associated substances play'an important part 'in the desired selective or step-bysteb hydrogenation. of fatty oils and in suppressing the formation of iso-oleic acids, a. fact which, as far as I know, has not-heretofore been realized. I have found that different catalysts, even though -they aretmade of the some metal, for example nickehhave varying intrinsic or specific properties in controlling the .course of the hydrogenation reaction, these properties being independent of their activity or amount used. It is not yet fully understoodwhy this occurs and I therefore do not .wish to, limit my invention to any theory of operaabove, such assulphur, arsenic, iron, etc. This catalyst. is made by precipitating electrolytically nickel hydroxide by passing direct current through a'cellusing nickel as the anode and using an electrolyte'consisting of the dilute solution of -an=alkali salt of a weakacid such as acetic acid.

Other known-methods of forming a precipitate electrolytically may be used. It should be noted that I- avoid the possible presence and introduction of substances which I have found destroy the actual selective character of the catalyst asv pointed out above.- The resultant hydroxide is reduced with hydrogen free from all sulphur compounds or other contaminating substances. I preferably use for reduction of my hydroxide the treated hydrogen disclosed in my joint application Serial No. 723,838 flled May -4, 1934. The reducing operation to make the nickel catalytically active is preferably carried out by heating the prepared nickel hydroxide to 300-500 C. in

a current of previously treated hydrogen. The

activated nickel thus formed is now in suitable 'form for use as a hydrogenation catalyst for the selective hydrogenation of vegetable oils into the improved edible fats in accordance with this invention.

This type of catalyst is substantially free from V .sulphidesas well as the other deleterious sub-' stances which have previously been present. The tendency of these substances previously present win-all hydrogenating catalysts to inhibit selective hydrogenation and their tendency to cause the formation of iso-oleic acid was apparently not noticed. I have found, however, that even minute mounts of these substances will sup- "press or destroy the desired selective'hydrogenationeffects and prevent the. formation of the ysuperiorhydrogenatedfats"characteristic of this 1 invention 1 Apparently previously. the effect 1 of wfiqtllese substances was not appreciated because theytwere present-Win such relatively small amounts. :1 a, V One of the practical advantagesoi electrolytic on tityusually beingiron anda little copper. Nickel i refined by lother processes may run as low as i 97% pure and israrely morethan' 99.5%.pure.

hydroxide, but satisfactory results can be ob- .talned also bydisjsolvingthe nickel in nitric acid m andprecipitatingthe nickel, as nickel carbonate,

with'soda ash. Anotheradvantage of electrolytic precipitation isijthatdt maybe carried out washing of the precipitate free from soluble salts sfcomparativelygeasy. n i i 1 This special gelectrolytio nickel catalyst, which iswsubstantiallyfree from all-components adcare mustbegtaken that, it does not contain harmful impurities which would modify the see i :iective action of thetcatalyst andacceleratethe formation of. iso-oleicacid. Although this type 2 only incidental to my selective catalyst" In fact.

some of the most mildlyactive kinds of catalysts -have been verycflectiveuin bringing about the.

preferredytypel oif hydrogenation reaction while someordinary catalysts, although extremely accelerate the formation or isomers or oleic acid. It is believed that n is due to the presence 5 of some or all. of the commonly. associated components mentionedwabov'e, even though, they are:

present in minute amounts i I hav. also found that a highly desirablese m thod an example of which is given. 200 parts 1 of acid ;-=washed infusorial. earth are suspended in solution of 100 parts 0. Prnickel nitrate and 5900 parts. distilled water maintained ata tems a of 450 parts, anhydrous C, P. sodium carbonate and 531001 parts distilled-water areadded very slowlytwithjviolent agitation]. The precipitate is collectedon a flltenand thoroughly washed 1 dried cake i then pulyerized and heated to 400: C. inafumace through which is passed a rapid streamrofdry hydrogen preferably of the treated to tim disclosed 111; my. mmmppncatmn referred to above. The reduction'with hydrogen. is carried out'untilthe evolution of water vapor ceases. i The catalyst is used in proportion of about eeth f ceu. a

" lt is very important that mywnew catalysts ybeprotected from harmful impurities during the qliydrogenation reaction since'even very minute traces of the so-calledfpoisons", which occur chiefly ill-the hydrogen gas, have a powerful 2,123,342 1 i l I i fnickeliswthat itsisa cheap sourceof very pure. nickeLv Electrolytic nickel very rarely runs below -99.5%-purity, including cobalt; thej 0.5%. impurv 1 The methodof electrolyticprecipitation is a convenient and economic method of converting the nickel into a reducible compound, '1. e.. nickel with very dilute electrolytesfso that subsequent versely affectinghydrogenation, may or may not given a carrier or support ofi inert material such zas-diatomaceous earth or kieselguhr; but in g the event; 1 that such a support is ,used extreme of catalyst usually possesses good activityand jefiects agfairly rapid reaction, this property is peraturejlietween. 60 and 80. C. The solution i with distilled water until free from ,soluble salts titer wmchitis dried-fin an oven at"110 c. The.

of 1% by weight of nickel tothe :weight of the andtend to make {the hydrogenation reaction modifying action on their exceptional properties non-selective and increases the formation of isooleic acid. A very effectiveimethod andmeans of ipurifying the hydrogen gasis described in my .Wp l m l ve o tsu e- In order to illustr te' thecom arative ability of different types of nickel catalysts and the u: periority of my new catalysts in controllingthe selectivity ofthe hydrogenation of unsaturated fatty oils, and theireflect on the formation of isomers ofoleic acid, severaleiramples are given below; The respective eilects of these catalysts arecomparedbycarrying out a carefully standardized reactionv whereby 2 k lograms of cottonseed oil are hydrogenated at agtemperatureof equivalent'to0.10%, of the weight of oil, asnickel.

In the four following examples I hydrogenated z 10 C. and a pressureof pounds per square inch with an amountjfof catalyst undertest the oil toa predetermined iodine value, which as shown above, measures the degree of saturation.

.When all the tests are carried out tothe same degree of saturation, e. g., 67.5 iodine value, an analysis of the hydrogenated samples will measureto what extentthe reaction has been selective andhow much iso-oleicacid has been formed The cottonseedoil used in each of these testshad anoriginal iodine value of 107.7

and wascomposed of glycerides or fatty acids in thefollowing proportions: 50.9% linollc, 22.7%

liquid at room temperatures, but when hydrogenated to an iodine value of 67.5, it will congeal pending) largely upon the effectiveness of the catalystiin suppressing the formation of saturated acids"andj iso-oleic acids, the cmcuctcr solid acids formed being indicated by the con gealing or solidification point. f a P c 4 catalystlsupported upon kieselguhr was prepared by methods commonly employed in i the industryifrom nickel whichhad been -recoveredfrom old catalyst. The oil hydrogenated to 67.5 iodine value under the standard conditions indicated above had a congealing orsolidiflcation'point (131.2 C. and the followinglfatty acid position: 14.1% flinollc, 50.1 01m, saturated acids. 1 i i 1 y Emcee {Ihissecond catalyst was-prepared fromcommercialcnickel sulphate by well-knownmethods by reducing nickel carbonate deposltedonkiesel- This catalyst is representative of what I g'uhr. have referred to as an ordinary type of catalyst. The oil hydrogenated under the same. standard conditions, using this catalyst, had a congealing point of 28.8 C. and was composed of fatty acids in the following proportions: 9.9% linolic, 58.4% oleicQand 31.7% saturated acids.

' Example 3 u i This third catalyst was prepared, according to olelc, and 26.4% saturated acids. Such anoil is one of mypreferred methods mentioned above,

iromthe purest grade of nickel nitrate obtainable from the chemical supply houses. Accordingly thefinal catalyst wassubstantially free from sulfates, sulfldesrand the other deleterious substances. The hydrogenated oil obtained when using this catalyst had a congealing point of 25.6 C. and the following fatty acid composition:

acids. v.

9.6%linolic, 59.1% olelc, and 31.3% saturated c Example! e .The fourthcatalyst was prepared, according to my preferred method, from electrolytically precommercial electrolytic nickel.

cipitated nickel hydroxide which was made from e The hydrogenate'd oil, produced in the presence of this 'catapoints obtained with; non-selective catalysts preparedfrom ordinary materials. shortenings prepared from such oils willbe. undulyjhard at the .de'gree of saturation required for good keeping properties and oils hydrogenated according to Ex-. ample 1 in particular havefahigh melting point I which renders them somewhat indigestible as food products, the high melting pointbeing caused by the relatively large amount of saturated [acids formed by this non-selective catalyst.

I r In Example .3 thereis obtained,'for the same degree of saturation as in Example '2, an oil whose congealing point is only 25.6" C. as against 28.8 C. in Example'2, although the fatty acid analyses are very similar. This is due to the fact that a high percentage of the oleic acidin Example 2 is in reality iso-oleic, acld,.as shown below. This iso-oleic acidincreases the congealing point and hardness of the product. In Example 3, the amount of iso-oleic acid is'relatively small, giving a very much softer fat for a fixed degree of saturation. It is evident, therefore; that oils which are hydrogenated'with thetype 'of catalyst used in Example '3 may be much more completely saturated with hydrogen to obtain the desirable consistency. t ereby reducing to a substantiallyfgreater extent the amount of highly unsaturated acid, i. a, linolic' acid, so that the hardened product hasremarkable' keeping properties. Also, it is not embrittled with iso-oleic acid.

, Example 4 illustrates astill greater improvement-in this respect in thatthe catalyst not only suppresses the formation of 'iso-oleic acid to the same or greater extent as in Example 3 but the amount of linolic acid is materially reduced without'increasing the'amount of saturated acids. In

fact the operation is accompanied by a reduction in the amount of the saturated acids. Shortenings prepared from oils hydrogenated with catalysts according to my preferred Example 4 are very plastic and "workable in addition to possessing high keeping ,qualities both as fat itself and in the subsequent food products in' which the fat is incorporated, such as cakes, doughnuts,

biscuits, potato" chips, etc. A The relatively low amounts of solid acids formed, with the consequent; low melting point of the fat, also makes these i'ats more digestible.

, In practice it is found unnecessary to actually determine the amount of isooieic acid in the final product, since the effect of this acid on the consistency of the product is readily appreciated by correlating the apparent fatty acid composition and the congealing point of the fat. For example, it has'been indicated above that although the apparent fatty acid analyses of Examples 2 and 3 are veryrsimilar, the congealing or solidincation points of the two fats vary by 3.2-degrees centigrade due to the presence in Example 2 of larger amounts of iso-oleic acids, which are included in the amount of oleic acid given under Example2, namely 58.4%.

1 Tosubstantiate the above given reasons for the superior characteristics of the edible fats prepared in accordance with my invention, I have made a determination of the actual amounts of solid unsaturated or iso-oleic acids for two samples of fat hydrogenated in accordancewith Examples. 2 and.3, supra. I have found that there is 13.5% .iso-oleic acid in the fat hydrogenated according to Example 2 and only 7.5% in that hydrogenated in accordance with Example 3. The product of Example 4 would contain. even less iso-olelc acid as indicated by the lower congeal point than thatof the product of Example 3.v

The 'catalyst'used' in Example 4-was therefore even more effective in the suppressing of i the formation "of .iso-oleic substances. An analysis of the products of Examples 2 and 3 shows the following: I

7 Solid acids Linolic Oleic Iso-oleic including acid acid acid iao-oleic acids Percent Perreut Percent Percent Example 2 9.9 44.9 13. 5 45.2 Example 3 9. 6 51. 6 7. 5 38. 8

catalysts in hydrogenated shortening manufacture, I have prepared four shortenings from cottonseed oil separately hydrogenated with the aid of the'catalysts described in Examples 1-4,

supra. The oil was hydrogenated under the same conditions as used in Examples 1-4 above, except that in the present tests the extent of hydrogenation was controlled by the consistency of the congealed fat instead of by its iodine value, that isythe oil was saturated with hydrogen in each caseuntil hardened products attained-the same general consistency or hardness when cooled to normal temperatures, the congealing or solidification point or each fat thus produced being about 29 C. I

When these'four fats were chilled and texturated by well known methods they produced shortenings of almost'identical degrees of harclness when compared at room temperature. Determination of the'iodine values, which as explained above, measures the degree of saturation, gave 6 9.0and 66.9 for the fats" hardened with the catalysts in Examples 1 and 2- respectively; These catalysts,'as stated'hereinbefore, are representative of ordinary catalysts employed in the industry. The fats hydrogenated with the new catalysts, of which Examples 3 and 4 are representative, had iodine values of 59.4 and 57 .8.

It is evident from the tests described just above that with the newv catalysts a substantially more complete degree of saturation can be obtained than with common catalysts, the improvement being equivalent to 7-11 iodine values and the product is still of the desirable soft consistency. It is also evident from the tests above that the keeping qualityof the shortenings prepared-using the new catalysts is greatly enhanced and the shortenings themselves possess improved plasticity over a comparatively wide range of temperature, due to the suppression of solid isomers of oleic acid or iso-oleic acid.

tended to include these acids as comprisedin fats and oils.

It is tobe understood that my invention isnot limited to the specific materials and methods described hereinbefore byway of example but is subject to various modifications, all of which come within the purview of the following claims. What I claim as new is: t 1. A hydrogenation catalyst capable of effectlng the selective step-wise hydrogenation of vegetable oils herein disclosed and suppressing the formation of iso-oleic acid, which catalyst consists of electrolyticnickel substantially free i from sulphides, said nickel being prepared from electrolytically" precipitated nickel hydroxide i which is subsequently converted into catalyti- I cally active metallic nickel by heat and contact a 2. A hydrogenation catalysthaving the property, in a vegetable. oil hydrogenating operation,

of selectively hydrogenating the more highly with hydrogen gas.

unsaturated fatty acids before the less saturated fatty acids are hydrogenated into solid saturated acids, and the property of, suppressing the formation of solid unsaturated fatty acidssuch as iso-oleic acids whereby thehydrogenated vegetable oil product thus produced possesses improved plasticity and keeping properties, said catalyst being made of metallic nickel substantially free from all impurities, said nickel being prepared from electrolytically precipitated nickel hydroxide which is subsequently converted into said metallic nickel by heating the nickel hydroxide in contact with pure hydrogen gas.

3. A hydrogenation catalyst having the propcity, in a vegetable oil hydrogenating operation, of selectively hydrogenating the more highly unsaturated fatty. acids before the less saturated fatty acids are hydrogenated into solid saturated acids, and the property ofsuppressing the formation of solid unsaturated fatty acids such as iso-oleic ,acids whereby the hydrogenatedwegetable oil product thus produced possesses improved plasticity and keeping properties, said catalyst being made of metallic nickel substantially free from all impurities, said nickel being prepared from electrolytically precipitated nickelhydroxide which is subsequently converted into said metallic nickel by heating the nickel hydroxide to approximately 300 Cr-500 C. in contact; with pure hydrogen gas.

4. A hydrogenation catalyst having the property, in a vegetableoil hydrogenating operation, of selectively hydrcgenating the more highly unsaturated fatty acids before the less saturated fatty acids are hydrogenated into solidsaturated prepared by passing directcurrent througha cell using nickel as the anode and using as-the electrolyte adilute solution of an alkali salt of a weak acid to electrolytically precipitate nickel proved plasticity and kgeping properties, said catalyst being made of metallic nickel substantially free from all impurities, said nickel being hydroxide insaid cell and heating said nickel hydroxide to approximately 300 C.-500 C. in

the presence of pure hydrogen to produce pure metallic nickel. i a 5. A hydrogenation catalyst having the property, in a vegetable oil hydrogenating operation, of selectively hydrogenating the more highly unsaturated fatty acids before the less saturated fatty acids are hydrogenated into solid saturated acids, and the property of suppressing the formation of solid unsaturated fatty'acids such as iso-oleic acids, whereby the hydrogenated vegetable oilproduct thus produced possesses improved plasticity and keeping properties, said catalyst being made of metallic nickel substantially free from all impurities, said nickel being prepared by passing direct current through a cell using. nickel as the anode and using as the electrolyte a dilute solution of sodium acetate to electrolytically precipitate nickel hydroxide in said cell and heating said nickel hydroxide to approximately 300 C.-500 C. in the presence of pure hydrogen to produce pure metallic nickel.

6. In a catalytic oil hydrogenation process for producing edible fats having improved plasticity and keeping propertieawthe step of contacting the oil with a catalyst 1 prepared from electrolyticallyprecipitated nickel that is substantially free from all impurities, in the presence of hy drogen andat a,hydrogenatingtemperature of not substantially more :than 150 -(2., whereby the formation of solid unsaturated fatty acids such as iso-oleic acids is suppressed and there is obtained a selective hydrogenationof themore highly unsaturated fatty acids before the less saturated fatty acids are hydrogenated.

7. In a. catalytic oil hydrogenation process for producing edible fats having improved plasticity and keeping properties, the step of contacting the oil with an electrolytic nickel catalyst that is substantially free from all impurities, in the presence of hydrogen and at a hydrogenating temperature of not substantially more than 150 C., said electrolytic nickel catalyst being prepared ,from electrolytically precipitated nickel hydroxide that is subsequently converted into catalytically active metallic nickel by heat and contact with pure hydrogen gas, wherebythe formation of solid unsaturated fatty acidssuch as iso-oleic acids is suppressed and there is obtained a selective hydrogenation of the more highly un saturated fatty acids before the less saturated fatty acids are hydrogenated.

WILLIAM J. ra'raason.