ON T H E CATALYTIC HYDROGENATIOX O F COTTONSEED OIL BY LOUIS KAHLENBERG AND GEORGE J . RITTER'
INTRODUCTION The purpose of this investigation is to study the catalytic process of the hydrogenation of cottonseed oil, in the hope of ascertaining the best conditions for conducting the process, and also finding new catalysts that will effectively bring about the reduction of the oil. To this end it was first necessary to make an exhaustive study of the literature of the subject. This study revealed the fact that to a large extent our knowledge of the actual process of the hydrogenation of oils is contained in the patent literature. Furthermore, in most of these patents in question, experimental details are not given sufficiently to enable one to duplicate the processes in the laboratory. It was consequently necessary to supplement the study of the literature with experimental nork in the laboratory to get a proper understanding of the known processes of the hydrogenation of oils. After such study, the investigation of unknown fields could proceed. This paper is consequently divided into the following parts : I . Historical Study of the Literature. 2 . Experimental Review of Certain Typical Known Catalytic Processes. 3. New Experimental Work. 4. Summary and Conclusions. I. HISTORICAL R E V I E W The process of hydrogenating unsaturated oils began in 1875, when Goldschmidt' succeeded in reducing oleic acid by means of hydriodic acid and amorphous phosphorus a t 200' C. TVilde and R e y ~ h l e rin , ~ 1888, heated oleic acid at 208' C I From a thesis submitted for t h e degree of Ph.D a t t h e University of LVisconsin. Sitzungsber. Akad. Wiss. IVien, 7 2 , 366 (1875). Bull Soc. chim. Paris, I , 295 (1889).
Loms Kahlenberg and George J . Ritter
90
with one percent of iodine and a small amount of tallow soap, and then boiled the mixture with acidulated water. By distilling the product part of the iodine was recovered from the pitchy residue. They claim to have obtained approximately a seventy percent yield of stearic acid. However, thirty percent of the iodine used could not be recovered in this process.' Weineck,2 in 1886, claimed that it was possible to hydrogenate oleic acid by means of the electric current. In a patent taken out by Magnier3 the oil is acidified with sulphuric acid, mixed with about five times its volume of water, and then subjected to the action of an electric current under five atmospheres of pressure. The nascent hydrogen generated by the current reduces the olein t o stearine. De Hemptinne4 reduced oleic acid to stearic acid by means of a method in which thin layers of the fatty acid were brought into the path of an electric current which passed through a chamber filled with hydrogen. His percentage yields were quite low. Petersen: succeeded in reducing oleic acid to stearic acid by passing a current of electricity between nickel electrodes immersed in an alcoholic solution of stearic acid acidulated with sulphuric acid. The yield in no case ran above twenty percent. Bohringer and SohneGworked on the same principle as Petersen, but they used platinum electrodes coated with platinum black. They obtained better yields than Petersen. One would expect fairly good results in this case, because platinum black is known to be a good catalyst. The nascent hydrogen generated by the electric current in the presence of the platinum black makes an ideal condition for the reduction of the unsaturated oil. Chem. Ztg., 595 (1889). Osterr Privil,, IO, 400, July 19 (1886). 3 British patent 3,363 (1900); German patent 126,446, October 3 (1899). 4 U. S. patent 797,112, August 15 (190j). 6 Zeit. Elektrochemie, 11, 549 (1903). 6 German patents 187,788, 189,332 (1906) l
2
Catalj‘tic Hydrogewation oj’ Cottonseed Oil
91
In 1871 Saytzeff reduced nitrobenzol to aniline by- passing a mixture of nitrobenzol vapors and hydrogen over platinum black, This research laid the foundation for an intensive study of hydrogenation by Sabatier and Senderens, who, in 1895,began their classic researches on oils by means of nickel and other metallic catalysts. These two ins-estigators have worked out the fundamental principles of oil hydrogenation by metallic catalysts. I n 1901 they took out the German patent 139~457for the reduction of nitrobenzol t o aniline. The German patent 141,c29 was issued to Leprince and Siveke in 1902.~ I t cos-ers the hydrogenation of oils in the liquid state by means of metallic catalysts. In the following year the English patent I ,j I j was granted to Normann. A controversy in regard to alleged infringement of patent rights between this and the Leprince patent, 141,029, led to a litigation which extended over a period of several years.4 Believing that a more intimate mixture of oil, hydrogen and catalyzer should be obtained in order to shorten the time required to reduce unsaturated organic substances with hydrogen, Bedford and Williams’ proposed to expose the oil in the form of a fine spray t o hydrogen gas in the presence of a nickel catalyst. By this treatment linseed oil was converted into a solid fat having a melting point of j 3 O C. Oleic acid was reduced to stearic acid with a melting point of 69 C. A diagram of the apparatus is shown in Fig. I , In 1910 palladium was first used as a catalyst commercially. The Vereinigte Chemische ‘\jlrerke6was granted the German patent 236,488 and in the following year the British patent I 8,642 was issued wherein palladium was precipiJour. prakt. Chemie, ( 2 ) 4, 418 (1871). Comptes rendus, 132, 2 1 0 , j66, 1 z j 4 (1901); Ann. Chim. Phys., 4, 319-
488 (1905). German patent 141,029 (1902). Ellis: “Hydrogenation of Oils,” p. 6 0 j (19191. English patent 2 , j 2 0 (1907). 4 German patent 236,488, August 6 (1910);British patent 18,642 (1911).
Louis Kahlenberg a.izd George J . Ritter
92
tated upon inactive bodies, and thus used for hydrogenating oils. Kayser,’ in 1911, introduced the idea of hydrogenating under pressure and a t the same time mechanically stirring in the oil during the reducing process. He used a nickel catalyst deposited upon “kieselguhr.” This method is of interest €or several “Crisco” factories in this country are using this process with slight modifications.* The diagram of Fig. 2 shows the important features of the apparatus used in this process. The process calls for the use of hydrogen under pressure, but no specified pressure is mentioned in the patent. Wilbus~hewitch~ was granted a patent which specified that the mixture of oil and catalyst should enter the top of the reaction chamber in an atomised condition. On descending in the flask the mixture meets an upward Fig I current of hydrogen. The partially reduced oil is then automatically pumped into the second of a series of reaction chambers, etc., until the desired product is obtained. A pressure of nine atmospheres is specified with a temperature of 160’ C. By working a t this low temperature it is claimed that a nice white f a t is finally obtained. Shukoff originated a unique method for hydrogenating oils. He passed carbon monoxide over metallic nickel a t 45’ to 75’ C to form nickel carbonyl. The vapors formed U. S.patent 1,004,035, September 26 (1911). “Hydrogenation of Oils,” p. 161 (1919). Swedish patent 992, May 2 7 (1911). German patent 241,823, January 18 (1910).
* Ellis:
Catalytic Hydrogenation
OJ
Cottonseed Oil
93
were conducted through cottonseed oil a t zoo' C. At this temperature the nickel carbonyl was decomposed into finely divided nickel and carbon monoxide. When a suitable amount of the nickel catalyst had been formed, the carbon monoxide current was shut off and a rapid stream of hydrogen was bubbled through the oil a t 2 2 5 ' to 240' C. I n five to six hours a f a t which solidified a t 40' C was obtained. The difficulty encountered in this process was that the catalyst being in such a fine state of division, settled out only after long standing. Winner and Higginsl observed that a very active catalyst
Fig. z
could be prepared by treating nickel formate with hydrogen at 300' C. They claim that the carbon of the formate aids in reducing the nickel oxide. In 1913 Hildescheimer2 found that metallic boron in the presence of hydrogen would reduce cottonseed oil. He assumed that the catalytic action depends upon the intermediate formation of BH3. High pressures and high temperatures are required. He also found that aluminium boride reduced unsaturated oils. An American patent states that, under pressure, tungsten, French patent 4 5 4 , j O I , February 18 (1913) Zeit. angew. Chem. Ref., 583 (1913).
I
Louis Kah1e.tzbel.g and George J . IZitter
94
molybdenum, thorium, uranium, zirconium, titanium, vanadium, and manganese may be used for hydrogenating oi1s.l Hamburger2 contradicts this statement. He clains that the above metals can not be used in reducing oils even under 2 0 0 atmospheres, Ellis3 prepared an active nickel catalyst by forming an electric arc between two nickel electrodes under water. Richardson prepared catalysts of nickel, copper, platinum, palladium, iron and their alloys by arcing electrodes of the respective metals under oil. This process gave the best catalysts when operated at pressures of 40 to 100 volts. ‘ The Oelverwerkung G. m. b. H . 4 describes a process for manufacturing a very active catalyst by mixing nickel nitrate with sugar and reducing with hydrogen a t 200’ C. The catalyst in this case is in a very voluminous condition. Rare Metal Catalyzers Paalj states that platinum and palladium are good catalysts. He recommends that the chlorides of these metals be treated with sodium carbonate and the precipitate formed be added to the oil and reduced with hydrogen. Colloidal platinum for reducing unsaturated bodies was first prepared by BredigGby means of the electric current in aqueous solutions of ether. Paal and Karl‘ found that palladium precipitated upon nickel, cobalt, and magnesium oxide was more active in hydrogenating oils than palladium when used alone. When palladium was deposited upon the oxide of lead, cadmium, zinc, aluminium, or iron its action was greatly diminished. Iridium, rhodium, ruthenium, and osmium are also specified as catalyzers for unsaturated oils.s Lehman states that 1
*
U. S.patent 1,026,156 (1914). Chem. Weekblad., 13, 2-13 (1916). U. S. patent 1,092,206, April 7 (1914).
Italian patent 130,384, March 13 (1913); Chem. Abs., 1 1 , 1279 (1916). Ber. deutsch. chem. Ges., 41,2 2 8 2 (1908). Ellis: “Hydrogenation of Oils,” 245 (1919). 7 Ber. deutsch. chem. Ges., 56, 3069(1913); Chem. Ztg. Rep., 642 (1913). 8 Vereinigte Chemische Werke -4.G . : French patent 425,729 (1911); Seifen Ztg., 1912,390. 4
Catalytic Hydrogenation of Cottomeed Oil
95
osmium dioxide is a good catalyzer. This is contradicted by Normann and Schick, who claim that it is metallic osmium which does the hydrogenating and not the di0xide.l Ellis’ found that cerium incorporated with charcoal makes a very good catalyst. Mannich3 states that platinum deposited upon charcoal is much more active than when the metal is incorporated with other inert materials, such as, silica or pumice. His view is shared by E l k 4 In 1916 Mittasch reported ruthenium as a catalyzer for hydrogenation processes.j Mannich and Thielefi found that by mixing powdered] ignited, animal charcoal with a 2 percent solution of palladium chloride] and passing into this mixture a stream of hydrogen, a large volume of the gas was absorbed. The water was then evaporated and the residue dried. This catalyst was found to be very efficient in hardening oils. It has good keeping qualities; is easily filtered from the melted fat without leaving any trace of the metal in the oil. Mannich recommends this catalyst highly for hardening peanut oil. Meyer,’ in 1912, reported the hydrogenation of olive oil with colloidal palladium hydroxide solution which contained 0 . 2 grams of palladium and 0.34 grams of gum arabic per IOO cc. Two volumes of olive oil and one volume of the palladium solution were heated and stirred in an autoclave a t 80’ C under a pressure of 6 atmospheres. Hydrogen was added to keep up the pressure; after one-half hour’s treatment the oil was separated from the catalyst. A solid fat was obtained. Ellis8 states that in hydrogenating with palladium compounds water must be present. I n this respect the palladium
3
(1919)
Seifen Ztg., 1914, 1 1 1 1 ; Ellis. “Hydrogenation of Oils,” 258 (1919). U. S.patent 1,167,280, January 4 (1916). Seifen Ztg., 1914,1174. U. S.patent 1,174,245, March 7 (1916). U. S.patent 1,173,532, February 29 (1916). Ber. deutsch. pharm. Ges., 26, 36-38 (1916). Dissertation, Karlsruhe (1912); Ellis: “Hydrogenation of Oils,” 2 5 3
* “Hydrogenation of
Oils,” 2 5 5 (1919).
Louis Kahlevzberg and George J . Ritter
96
process differs from hydrogenating with most of the other catalysts. Cottonseed oil treated with colloidal palladium and hydrogen showed no reduction. KO reduction took place when the reaction was conducted in alcohol or acetone, but on adding about 15 percent of water reduction took place rapidly. He states that formaldehyde and mustard oil are very “poisonous,” meaning, of course, that these substances inhibit the process. Mannich and Thielel found that the capacity of palladium for adsorbing hydrogen is greatly increased by mixing animal charcoal with the metal. A catalyst for hardening unsaturated oils can readily be prepared by shaking ignited powdered animal charcoal with a two percent solution of palladium chloride, and passing hydrogen into the mixture until no more of the gas is adsorbed. The powder is then washed and dried. This catalyst has good keeping qualities. Sulsberger2 states that a good palladium catalyzer can be prepared by treating palladium chloride with sodium oleate. This gives a compound which readily dissolves in cottonseed oil. The oil is rapidly hardened with this catalyzer. In reviewing the subject of the hydrogenation of oils it is noted t-hat most of the catalysts used are found in Group 8 of the periodic table of elements. Of late years considerable experimental work has been done on some of the rare elements. Commercially, nickel and cobalt play the important r81e as catalytic agents in preparing lard substitutes. The methods of preparing these agents are many. In the arts, the preparations are trade secrets. Description of a few laboratory reproductions of some of the hydrogenation processes described in the literature now follows in Part 11. These experiments were found to be necessary in order to become thoroughly acquainted with the details of the hydrogenation process and so form the basis for the original investigation of Part 111. The rather meager description of the hydrogenation processes in the ~
1
*
Ber. deutsch. pharm. Ges., 26, 36-48 (1916). U. S. patent 1,171,902,February 15 (1916).
Catalytic Hydrogenation o j Cottonseed Oil
97
patents was found to be quite inadequate to enable one to go ahead with original work on the subject. Since such experimental details are not given in the literature, these preliminary experiments are not omitted here, but are described in sufficient detail to enable others to profit by what was actually done in this laboratory.
11. EXPERINENTAL REVIEW OF A FEW KNOWN PROCESSES N i c k e l Catalyst Twenty grams of nickel nitrate were dissolved in 1 2 0 cc of distilled water and 2 0 grams of finely ground pumice were thoroughly stirred into the solution. The mixture was placed on a steam-heated sand bath to evaporate off the water. The cake formed was thoroughly ground in a mortar. The pulverized mixture was heated in a casserole to dull redness, with constant stirring, until the brown fumes of nitrogen dioxide were no longer evolved. The black mixture of pulverized nickel oxide and pumice was transferred to a hard-glass tube which was placed in an air bath a t 3 jo" C. A current of hydrogen was passed through the tube which was constantly rotated so as to secure intimate contact of the hydrogen and nickel oxide. After three hours' treatment in this manner, the material was allowed to cool to room temperature in the hydrogen atmosphere. The cooled catalyst was introduced into 2 0 0 cc of cottonseed oil which had been previously heated to 100' C and treated with a rapid current of hydrogen for a few minutes. In order to avoid contact with the air, the transfer of this catalyst mas accomplished by opening one end of the tube, containing the catalyst, under the surface of the oil and passing hydrogen into the other end of the tube. The charge of oil and catalyst was transferred to the apparatus of Pig. 3, in which the hydrogenation was carried out. The bath was heated to 180' C and hydrogen from a pressure tank was bubbled through the cottonseed oil. Samples were taken a t intervals of an hour. At the end of the fourth hour it was found that the oil had become semi-solid
98
Louis Kahlenberg and Geovge J . Ritter
on cooling to room temperature. At the end of five hours i t solidified a t room temperature. A t the end of six hours the sample had a melting point of 35 O C.
Cobalt Catalyst Twenty grams of cobalt nitrate were dissolved in 1 2 0 cc of hot distilled water and 2 0 grams of powdered pumice were mixed with this solution. The mixture was then treated in the same manner as the foregoing preparation of the nickel catalyst. Two hundred cc of cottonseed oil were hydrogenated a t 180' C with this cobalt catalyst in the apparatus of Fig. 3 and samples were taken at hour intervals. It was found that a sample, at the end of six hours, be_-_ came semi-solid at room temperature. A t the end of seven hours the oil solidified at 2 5 ' C. After eight hours' hydrogena- - - - - - -tion the sample melted at _ _ _ _ _ _ =------6 30' C. Further treatment did not raise the melting point. The nickel seemed to be the more efficient catalyst, both as Fig 3 to time and also as t o the percentage yield of saturated oil.
4
Nickel-Cobalt Catalyst Ten grams of nickel nitrate and I C grams of cobalt nitrate were dissolved in 1 2 0 cc of hot distilled water. The water was evaporated off and the residue treated in the same manner as the cobalt and nickel residues just mentioned. The catalyst obtained in this case was used for reducing 2 0 0 cc of cottonseed oil in apparatus of Fig. 3 . It was found that samples taken at hour intervals had a higher melting point
Catalytic Hydrogenation of Cottomeed Oil
99
than thg corresponding samples when cobalt or nickel was used alone. In this case the oil became semi-solid a t room temperature after two hours' treatment with hydrogen. In three hours the oil solidified a t 2 j " C . At the end of five hours it melted a t 42' C. On further treatment the melting point remained unchanged, showing that equilibrium had been reached. Iron Catalyst Twenty grams of ferric chloride were dissolved in distilled water and I j grams of powdered pumice were stirred into the solution. While rapidly stirring, the required amount of sodium carbonate solution was added to precipitate the iron. The solid was filtered off, washed with warm distilled water, dried, heated to drive off the carbon dioxide, placed into a hard glass tube and heated to 3 j o " C in a current of hydrogen. After five hours of the latter treatment no more water was given off. Without admitting air to the catalyst, the iron pumice mixture was transferred t o 2 0 0 cc of previously heated cottonseed oil. The mixture was placed into the apparatus of Fig. 3 and hydrogen bubbled through it a t I 80 " C for ten hours. A sample taken after ten hours showed a reduction of the iodine number from 108 to 90. Theoperation was continued for 20 hours. The iodine number was thus finally reduced to 85. The experiment was repeated by precipitating the iron as ferric hydroxide with ammonium hydroxide. In this case the iodine number was reduced to 84 j in 20 hours.
Iron-Nickel Catalyst Fiye grams of nickel chloride and I j grams of ferric chloride were dissolved in distilled water. The remaining procedure was identical with that of the iron catalyst just described. The iodine number of 200 cc of cottonseed oil treated with this agent and hydrogen a t 180" C in the apparatus of Fig 3 was reduced to 75 in 8 hours, but it could not be lowered by more prolonged treatment.
IO0
Louis Kahlelzberg azd George J . Ritter Other Iron Mixture Catalysts
Iron-cobalt and iron-copper were analogously tried with little success. These results are in accord with those reported in Ellis' "Hydrogenation of Oils," p. 146. The activity of nickel, cobalt and iron as oil-hardening agents diminishes in the order named. 111. EXPERIMENTAL INVESTIGATIONS
Having thus successfully duplicated several of the processes recorded in the literature, it was decided to proceed to find new catalysts, and study the best conditions for employing them. Zinc salts were successfully used in the following manner : I.Zinc Catalyst Fifteen grams of zinc nitrate were dissolved in distilled water. To this solution eight and one-half grams of sodium carbonate were added to precipitate zinc carbonate. The zinc carbonate was filtered off and washed with distilled water to remove all traces of the sodium salts. To obtain zinc oxide the carbonate was heated at 300' C in a porcelain dish over a Bunsen burner, so as to drive off the carbon dioxide. The zinc oxide was reduced with h y h o gen at 350' C to 450' C for five hours. During the reducing process the hot zinc substance changed from yellow to a gray color. A cooled sample of this material when treated with hydrochloric acid liberated hydrogen, thus showing that metallic zinc was present. The zinc catalyst was transferred into 2 0 0 cc of previously heated cottonseed oil, by opening one end of the tube containing the catalyst under the surface of the oil. The hydrogenation was carried out a t 180'-190' C in the apparatus shown in Fig. 3. It was found difficult to keep a good suspension of zinc in the oil. After eight hours of hydrogenation, a product was obtained which appeared as a brownish semisolid at room temperature.
Catalytic Hydrogenation
OJ
Cottonseed Oil
IO1
2. Zinc, Aluminum Catalyst
I n order to secure a better suspension of the catalyst, the zinc carbonate was next precipitated in the presence of powdered aluminium in suspension. I n this case three grams of the aluminium were stirred into the zinc nitrate solution before adding the sodium carbonate. The remainder of the procedure in preparing this catalyst was identical with the preparation of the preceding catalyst. Two hundred cc of cottonseed oil were hydrogenated with this catalyst in the apparatus shown in Fig. 3 . I n this case a good suspension was obtained on rapidly bubbling hydrogen through the mixture. Samples were withdrawn a t one hour intervals with the following results, shown in Table I.
TABLEI ____
KO of Sample
Orig. oil I
-7
3
1 5 6
-,
T i m e of Treatment
-
Melting Point
"C
liquid
Iodine Vumber (Hams)
108.0 96.2 85.4 8i.7 79.1 78.6 63.0 63 . 0
Refrac. Index 40' C (ilbb6) I
,4642
I . 464r 1 ' 4637 I ,4650
,4616 1.460j I ,4600 r ,4600 I
After the hydrogenation, the oil in the ap aratus was kept at 70' C over night to allow the catalyst to settle. The clear oil was siphoned off and 2 0 0 cc of previously heated oil was poured into the apparatus. This second charge was then hydrogenated a t the same temperature as the first quantity. Samples were siphoned off a t one hour intervals. The results are given in Table 11. By comparing corresponding samples in Tables I and I1 it is seen that they agree fairly well. Some discrepancies do occur. For instance, sample 6 in Table I has a melting point of 2 9 . 8 ' C with an iodine number of 63. The corresponding
Louis Kahlewberg avzd George J. Kitter
I02
S o of Sample
I I
Time of Treatment
llelting Point "C
'
1, Kumber Iodine 1 1 (Hanus)
I
1
!
Refrac. Index 40°c
Orig. oil I 2
3
1 3
6
.
sample in Table I1 has a melting point of 29.0' C and an iodine number of 62. Unavoidable experimental error is undoubtedly the cause of these differences. It was found that ten hours of hydrogenation under the conditions used brought about the maximum reduction of the unsaturated oil. KO further addition took place on continued treatment. The iodine number in all cases of this research was determined by the Hanus method. The melting point of the hardened oil was determined by allowing the capillary tubes containing the solidified fats to remain in a freezing mixture twelve hours before introducing them into a water bath t o note the temperature a t which the f a t became transparent. The index of refraction was determined by an Abb6 refractometer a t 40" C. The saponification number was obtained in the usual way by saponifying in alcoholic potash.
3. Aluminum as Catalyst Since the aluminum was used in connection with the zinc in preparing the catalyst in the preceding case, the question arose whether aluminum might not be responsible for the increased activity of the catalyst. Three grams of powdered aluminum were heated from 3j o C to 4jO C in a current of hydrogen for five hours. It was transferred without coming in contact with the air to 2 0 0 cc of previously heated cottonseed oil The mixture was placed into the apparatus of Fig. 3,
Catalytic Hj'drogeiiatioit o j Cottoizseed Oil
103
heated t o 18oo-19o3 C and hydrogen bubbled through the oil for I O hours. Upon cooling a sample in ice water, no sign of hardening appeared. 4. Zinc, Powdered Charcoal Catalyst
A catalyst was prepared in the same manner as in ( 2 ) , only that 5 grams of acti1Tated powdered charcoal were substituted for the aluminum. Two hundred cc. of prel-iously heated oil were mixed with the catalyst, and treated with hydrogen in the apparatus of Fig. 3. After 1 5 hours' treatment and cooling in ice water, only a slight thickening of the oil appeared. The results were not as good as when zinc was used alone in ( I ) abo.\-e. 5 . Zinc, Pumice Catalyst In this case the preparation of the catalyst, and the hydrogenation process was a duplication of procedure 2 except , that powdered pumice was substituted for the aluminum After bubbling hydrogen through the oil for 15 hours a product mas obtained which solidified a t 40' C, but no further reduction took place. From these experiments i t appears that aluminum, when used in conjunction with zinc, has some specific action even though when used alone it produces no reduction of the unsaturated oil with hydrogen. On the other hand. pumice which was found to act as a good carrier when used with nickel, retards the catalytic action of zinc. 6. Zinc Aluminum Catalyst prepared from Zinc Nitrate
E'ifteen grams of zinc nitrate, fifty cc of distilled mater and two grams of powdered aluminum were mixed in a solution. After evaporating to dryness, and then heating t o dull redness to drive off oxides of nitrogen. the residue was reduced a t 350' C to 450" C in a stream of hydrogen for five hours. The catalyst was added to 2 0 0 cc of previously heated cottonseed oil. The mixture was placed into the apparatus of Fig. 3 and heated to 190' C. Hydrogen was bubbled
Louis Kahletaberg and George J . Ritter
I04
through the mixture for I O hours. On cooling a sample, no congealing was apparent. The relatively high temperature required to break down the nitrate to the oxide of zinc is perhaps the cause of producing an inactive zinc catalyst from the nitrate.
7. Bismuth, Charcoal Catalyst Ten grams of bismuth subnitrate were dissolved in distilled water slightly acidified with nitric acid. To the solution three grams of powdered activated charcoal were added. While rapidly stirring, six grams of previously dissolved sodium carbonate were slowly added. The precipitate was transSerred to a filter, washed to remove all the sodium salts, and dried at I j o o C. To drive off the carbon dioxide, the mixture was heated to 325' C for two hours. Reduction of the oxide was carried out in a hard glass tube at 3j o ' C in a current of hydrogen from a pressure tank. Without exposure to the air the catalyst was transferred to 400 cc of previously. heated cottonseed oil. The charge of oil and catalyst was placed into the apparatus of Fig. 4, in which hydrogenation may be carried on under pressures up to five atmospheres. Experiments were carried out with different combinations of temperatures and pressures to ascertain the best conditions for hardening cottonseed oil, with the catalyst in question. The results of these experiments are as follows : A. Hydrogenation a t 160' C and 30 lb. pressure. Samples of oil were withdrawn from the apparatus at one hour intervals up to twelve hours. I n all the cases the oil showed no signs of solidifying on being cooled to 5' C. B. Hydrogenation a t 160' C and 40 lb. pressure. Samples taken at hour intervals gave negative results, i. e., none of them solidified on being cooled as in A. C. Hydrogenation at 160' C and 50 lb. pressure. I n this case samples were taken in the same manner as in A and B. The results again were negative. 1
This apparatus was obtained from Sieck & Drucker, Chicago.
Catalytic Hydrogevatiqn of Ccttowseed Oil
105
D. Hydrogenation at 160' C and 60 lb. pressure. The pressure was then raised to the maximum capacity of the apparatus, i. e., 60 lb. The samples taken as in A did not show any signs of solidifying. E. Hydrogenation a t 170' C and 30 lb. pressure. The temperature was then raised to 170' C and the pressure
Fig. 4
varied from 30 lb. to 60 lb. Samples obtained while working at 30 lb. pressure and 170' C showed slight signs of hardening on being cooled. This was especially true in the tests made on samples taken after the sixth hour interval. F. Hydrogenation a t 170' C and 40 lb. pressure. Samples taken at hour intervals were cooled as in the previous cases. The results were the same as in E. G. Hydrogenation a t 170' C and 5 0 lb. pressure. Tests
I 06
Louis K a h l e d e r g alzd George J . Ritter
made on samples in this case showed signs of slight hardening as in E and F. H. Hydrogenation a t 170' C and 60 lb. pressure. The pressure was next raised to its maximum. Tests made on samples gave the same results as under G. I. Hydrogenation a t 180' C and 60 Ib. pressure. The pressure in this case was kept at 60 lb. and the temperature was slowly raised from 170' to 180' C. When 180' C was reached, it was observed that the temperature of the oil mixture suddenly rose to 185 ' C, even when all external heating was removed. The temperature then gradually rose to a maximum of 190' C. It remained there for one-half hour and then slowly lowered to 175 ' C in one hour. External heat was again applied t o raise the temperature to 180' C. A sample taken at the end of six hours and cooled was found to solidify into a dark brown mass. On remelting and filtering the sample to remove the catalyst, it was found that the oil had a melting point of 25' C. Samples taken at the end of eight hours had a melting point of 28' C. E'urther treatment of the oil failed to raise the melting point. I n all these samples it was observed that the oil had a burned odor, whereas when heated to 170' C, as in H, no such odor was noticeable. An attempt was made to determine the cause of this charring, by keeping the temperature constant and altering the pressure. A new charge of oil and catalyst was placed into the apparatus of Fig 4. Hydrogen was allowed to bubble through the mixture while the temperature was slowly raised to I 80 ' C. When I 80 ' C was reached, the temperature again suddenly rose to 185" C', and then slowly continued to rise until a maximum of 190' C was reached. After one-half hour it gradually receded as in case I. External heat was again applied, and the hydrogenation was continued for ten hours. A sample taken a t the end of seven hours had a melting point of 26' C. A sample at the end of eight hours had a melting point of 28 ' C, which was the maximum melting point obtainable even on continued hydrogenation. The
e
Catalytic Hydroge7qatioia
0.t
Cottonseed Oil
10j
oil in this case also had a dark brown color and a charred odor. From the last two experiments, i. e., hydrogenating a t 180' C and 60 lb. pressure, and 180' C and atmospheric pressure, it is clear that pressures of five atmospheres did not aid the hydrogenation of cottonseed oil, when bismuth was used as the catalyst. It was also noted that the pressure had nothing to do with the charring of the oil, for the charred odor was the same when the operation was carried out under atmospheric pressure. Since the apparatus in Fig. 4 is heated with a gas flame it was believed that superheating might cause the charring of the oil. This was actually shown to be the case, when a charge of oil and catalyst was placed into the apparatus of Fig. 3 in which a glycerine bath was always used for heating the oil. In this case the charge was hydro: genated at 180' C by bubbling hydrogen through the mixture. Samples were removed a t one hour intervals. The oil solidified into a white fat, when cooled to room temperature. S o charred odor could be detected in this case. This bears out the statement made above, that superheating of the apparatus of Pig. 4 caused decomposition of the oil. The important constants of the hardened oil are given in Table 111 below. It was next decided to ascertain the duration of the catalyst's activity. To do this, the clear, oily liquid was siphoned off from the catalyst, and a new charge of two hundred cc of cottonseed oil was added. The temperature was controlled at I 80 O C and a current of hydrogen was rapidly bubbled through the mixture. The results are recorded in Table IV. The same catalyst was again used with a third charge of cottonseed oil. These results are shown in Table V. The bismuth-charcoal 'catalyst used in the three experiments (cf. Tables 111, IV and V) shows concordant results when corresponding samples of Tables 111, IV and V are compared. The slight variations fall within the range of experimental error. In Table V it is seen that the catalq-st has declined in activity. The minimum iodine number in this table is 7 0 , whereas in Table IV the lowest iodine number is 63 8.
L o u i s Kahlenberg and George J . Ritter
108
TABLEIT1
--
Hours Melting Point Treatment OC
K O . of Sample
Iodine (Hanus)
-
Orig. Oil I
Sapon. Number
Refractive Index 4 o o C (Abbe)
108.0 98.0 90.0 85.2 77 . o 64.5 65.2
semi-solid 25 ' 28' 28'
I . 4642 I . 4641 I .4640 I . 4636
I ,4618 I I
.4613 ,4612
TABLEIV '
1 Hours Melti?g Point Treatment
:
No. of Sample I
4
2
5 6
3 4 5 6
1
1 1
-
semi-solid 27.0
6
28.2 28.2
9
I
1
No. of Hours Melting Point O C Samples 1 Treatment
1 ~
I
2I
1
5
3
1
6 7 8
6
IO
semi-solid 25.0 26.0 26.0
Sapon. Number
96.0 89.0 86. o 75.0 64.0 63.8
-
7
Iodine Number (Hanus)
I
Iodine Number (Hanus)
97.0 91 . o 84.5 76.2 70.0 7 0 .I
Refractive Index too C (Abbe) I .4640 I . 4638 I ,4636 I ,4616 I ,4612 1.4611
1
I
Sapon. Number
I 400g$&,6) Refractive
I . 4641 I
,4640
1 ,4635 I
,4618
I . 4615 I ,4613
Since small amounts of metallic bismuth have no toxic effects upon the human body, it was hoped that a good active catalyst might be prepared from this element. This would eliminate the necessity of removing small traces of the catalyst, as in the case when nickel is used for hardening oils intended as lard substitutes. The results which were obtained with
Catalytic Hydrogenation o j Cottonseed Oil
I09
bismuth in this research indicated that equilibrium is reached too soon between the olein and the stearine formed, i. e., the percentage of saturation cannot be carried far enough to completion for preparing lard substitutes. Perhaps a good bismuth catalyst might be prepared by other methods, such as replacing the metal from a solution by some metal farther up the scale of the electrolytic series. This would eliminate high temperatures in preparing the catalyst and so might produce an active, and a t the same time non-poisonous, catalytic body. On account of lack of time this method of preparing a bismuth catalyst was not undertaken. In preparing a nickel catalyst from the nitrate, a glowing temperature is required to remove the oxides of nitrogen. Then to reduce the nickel oxide with hydrogen a temperature of 350' C must be used. Xickel catalysts heated above 3j o C in their preparation are generally inactive in hydrogenating processes a t temperatures below 180' C and atmospheric pressure. With this fact in mind, it was undertaken to prepare a nickel catalyst a t lower temperatures than those reported in the literature. It was believed that a catalyst prepared a t a low temperature would hydrogenate cottonseed oil below I 80' C, and thus eliminate all danger of decomposing the oil during the process of hardening. This attempt was successful, as will be seen in 8 and I O below. 8. Replaced Nickel as Catalyst Chemically pure granulated zinc was placed into a saturated solution of nickel chloride. At the end of three hours a dark coating of nickel was deposited upon the surface of the metallic zinc. This zinc-nickel material was washed with previously boiled warm water to remove any adhering nickel chloride. The substance was dried in an atmosphere of hydrogen a t 125' C for one hour. The surface had a black velvety appearance. This catalyst was transferred to some previously heated cottonseed oil and the mixture was treated by bubbling hydrogen through it a t 150' C in the apparatus of Fig. 3. A sample taken a t the end of one hour showed the
Louis Kahlenberg and George J . Riiier
IIO
effects of hardening. The hardened product had a slight brownish tinge, but was much lighter than that obtained with the zinc catalyst. The results of this run are recorded in Table VI. It was found that the same catalyst can be used for hardening several successive charges of oil without showing any decrease in its activity. Four such runs were made. The data are given in Tables VI, VII, VI11 and XI, respectively. '1'ARI E
-
~I
y o . of Samples
~
~
Hours Treatment
I hIelti2g Point I
Orig. oil
~
2
1 2
'
3
3
4 5
3 4
-
1
6
(Hanus)
Hours Treatment
1
0
963
90
2 8 2 0
I
i
liquid semi-liquid
2
27
3
27.9 37.2 37.1
4 3
Hours Treatment
Melting Point "C
Orig. oil
-
liquid semi-liquid
I
2
2
3
3 4
4
3
2
'3.3 28.4 37 .o 37.2
~
40' C (Abhk)
~
1
I
1i
195
I . 4642
-
I . 1638
-
1
I
Sapon
i
I
,
I
~
Refractive 4 0 ° C (Abbe)
,4642 1.4637 1 1635 I ,4617 '
I . 4601 I ,3601
~
108.0
,4600
I
1
i '
4638
1.461j
I
Iodine Number (Hanus)
'
I , 4629
108 o r9j 90 i 86 66.3 I 62 61 I 193 2
-
XO. of Samples
Refractive . Irdex
sapon.
61j 1 62 I 193 8
'
I
Melting Point '1 Number Iodine O C (Hanus)
I
Orig. oil
j
I -108
TABLEVI1 ,
i I
1
'
__
S o of Samples
~
liquid 1 liquid semi-liquid 26 3 36 j 37
_____
I
Iociine N,lmher
,!
Refractive Index Number 40' C (Abbe) Sapoll
195
Catalytic Hydrogenatio7z of Cottoitseed Oil
111
TABLEIX Hours Treatment
x o , of Samples
-, -
Orig. oil I 2
3 4 5 6
2
liquid semi-liquid
3 4 5 6 8
25.2 29.3 35,0 .36.I 36.5
I08 . o 92.3 79.1 65.0 60.0 59.4 60. I
I
I . 4642 I . 4638 I ,4620 I . 4615
4600 ,4598 I $596 I I
'
A study was made of the optimum temperature for hydrogenating cottonseed oil with the replaced nickel-zinc catalyst. Fifty cc samples of previously heated cottonseed oil were treated by bubbling hydrogen through the oil in the presence of the above catalyst. Runs were made a t 150' C,160' C , 170' C, 180' C and 190' C. Table X contains the results TABLE
X . _ I _
\
Temperature Time in "C 1 Hours ~
I
150 160 170 180 190
,,
I
I
1
I
I
Iodine x,lmber
l
(Hams)
' Melting" CPomt I
I
bj I
I
I
70
1
5 29 o
I
68 3 66 2 661
1
33 2 35 2 35 o
~
1
2
I
~
Remarks
I
1
I
4 4 4 4 4
I
27
~
1
1
'
IVhite solid LThite solid nlbite solid Il'hite solid Brownish colored Slwhtl~charred
,5 study of Table X reveals the fact that 180' C is the optimum temperature for hardening the cottonseed oil when the process is carried on a t atmospheric pressure. A t this temperature the action is completed in less time than at lower temperatures, and a t the same time no decomposition of the oil occurs. This fact is indicated by the melting point and iodine number. 9. Granulated Zinc as Catalyst Five grams of arsenic-free granulated zinc were treated with a current of hydrogen a t 125' C for one hour. One
II2
Louis Kahlenberg t ~ " r ~George d J . Ritter
hundred cc of previously heated cottonseed oil were added to the catalyst. The mixture was hydrogenated in the apparatus of Fig. 3 at 180' C for ten hours. On cooling the oil to room temperature no apparent hardening was noted. This demonstrates the fact that granulated zinc cannot be used alone in hydrogenating cottonseed oil. It is clear then as a result of this study that metallic nickel deposited upon arsenic-free granulated zinc is a new catalyst which is more efficient at temperatures below 180' C and atmospheric pressure, than any other nickel catalyst thus far reported in the literature. 10. Nickel Catalyst from Niekel Chloride
Ten grams of Kahlbaum's C. P. nickel chloride were pulverized, placed into a hard glass tube, and subjected to a current of hydrogen at a temperature from 180' C to 250' C. When 180' C was reached it was noted that silver chloride was precipitated by passing the escaping gas through silver nitrate solution. The temperature was gradually raised to 2 jo' C and kept there until no more silver chloride was deposited. The residue in the reducing tube has a slightly brownish black color. This residue was transferred without contact to the air to zoo cc of heated cottonseed oil and the mixture was introduced into the apparatus of Fig. 3. While hydrogen from a pressure tank was being slowly bubbled through the mixture the bath was brought to 180' C and then the current of hydrogen was increased t o a rapid bubbling. Samples were taken at hour intervals. It was found that this catalyst reduced the oil to a solid mass in six hours. The results of the study are found in Table XI. Since this catalyst had been prepared at a much lower temperature than the catalyst obtained by reducing nickel oxide (3j o ' C), it was decided to attempt to hydrogenate the oil a t I jo' C, as in the case of nickel replaced by zinc in 9 above. In Table XI it is seen that a solid fat was obtained in five hours. Runs were then made in the apparatus of Fig. 3
Catalytic Hydrogenation o j Cottonseed Oil
113
with the reduced nickel chloride catalyst at temperatures ranging from 150' C. to 190' C. These results are found in Table XII. TABLE XI Sample
Hours of Treatment
vIeltiEg Point
Orig. oil
-
liquid liquid semi-solid
3 4 5 6
I 2
3 I 6
Temperature
'1'
Sapon. Number
Refractive Index to O C (Abbil)
108.0 94.0
I
80.4 78. I 70.3
30 3I 34
,4642
-
I . 4619
61 . 3 60.0
I
,4600
I
,4601
TABLEXI1 Time in Hours
1
~
~
-I
Ij0
j
I 60
5 5
170 I80 190
Iodine Number (Hanus)
27
7 8
3
C
I I
j 3
1
Iodine Number (Hanus)
1
1
Melting Point "C
I
106.0
85 . o 79.2 66.5 66.8
liquid semi-solid 22
30 30.2
The data of Table XI show that the catalyst prepared by reducing nickel chloride is quite active. I n five hours cottonseed oil is hardened to a melting point of 2 7 C. In seven hours the melting point of the hardened oil is raised to 34' C. The latter product has a good consistency for market purposes. From Table XI1 i t is seen that the catalyst hardens the oil a t 170' C. In five hours the iodine number is reduced from 108 to 79.2. The most efficient temperature, however, is 180' C, for in this case time is saved, and a t the same time the oil is not decomposed by excessive heating. IV. SUMMARY AND CONCLUSIONS The object of this research, as stated in the beginning, was to find new catalytic agents for hydrogenating cottonO
11.4
Louis Kahlewbeyg and George J . Ritter
seed oil. On reviewing the results obtained the following conclusions may be drawn: I . Sickel is the most efficient common metal catalyst for hardening cottonseed oil. The fact that nickel is the best single metal catalyst for hydrogenating oils is in harmony with what others have found. 2 . A half-and-half nickel-cobalt catalyst was found to be more active than either metal, when used alone. 3 , Two new nickel catalysts were prepared, namely : (a)Nickel deposited upon arsenic-free granulated zinc in a saturated solution of nickel chloride. This catalyst was prepared a t lower temperatures than other nickel catalysts. I t hardens cottonseed oil, under atmospheric pressure, a t lower temperatures than any other nickel catalysts hitherto described. ( b ) Nickel chloride reduced with hydrogen at 180' C t o 250' C. This is also a good catalyst. It brings about hydrogenation of cottonseed oil fairly well a t 170' C. 4. Zinc carbonate freshly precipitated in the presence of suspended powdered aluminum, and reduced a t 350' C to 504' C makes a fairly good catalyst for hardening cottonseed oil. j . Bismuth precipitated upon charcoal and reduced with hydrogen a t 3 j o O C is a fairly active agent for reducing unsaturated oils. Clzenaical Laboratory Cn;lzzversttyof Wiscoiasiiz Mudisolz, .Vovember, 1920
