ON THE CATALYTIC HYDROGENATION O F CERTAIN OILS BY LOUIS KAHLENBERG AND TSU PEI PI
I n a previous article' on the catalytic hydrogenation of cottonseed oil a number of new catalysts were mentioned and the conditions under which the best results may be obtained with them were described. The present paper is a continuation of that research, the object being to find still other and more effective catalysts and to test these not only on cottonseed oil, but also on soy bean oil, olive oil, corn oil, neat's foot oil, and fish oil, as well as on the free fatty acids actually prepared from each of these oils in the laboratory. The method of experimentation was exactly the same as that employed before, the hydrogenation being conducted a,t atmospheric pressure in this case in the apparatus shown in Fig. 3, J. Phys. Chem. 25, 98 (1921). The hydrogen used was ordinary commercial hydrogen obtained in compressed form in steel cylinders. The gas mas passed through concentrated caustic potash solution and then through concentrated sulphuric acid before conducting it into the oil to be hydrogenated. The experimental results obtained follow:
Hydrogenation of Cottonseed Oil with Various Catalysts I. Nickel oxide catalyst. About ten grams of nickel nitrate were decomposed by heating in a porcelain crucible. After the evolution of NO2 had ceased, the resulting nickel oxide was subjected to reduction by hydrogen a t 335' to 340' C for three hours. The reduced substance was then carefully transferred to the tube2 containing IOO C.C. of cottonseed oil. The hydrogenation was conducted at a temperature of 210' C. After three hours, the oil solidified at room temperature. Its iodine number had been lowered from 109 to 63, and its melting point had become 41' C. Nickel molybdate catalyst. Ten grams of nickel chloride were dissolved in 2 0 0 cc of distilled water. To this solution, about eighteen and one-half grams of sodium molybdate dissolved in zoo cc of water were added. The precipitate was washed until free from sodium salt. The nickel molybdate was dried, ground to a fine powder, and finally reduced in a current of hydrogen at 350'-360' C for three hours. The catalyst thus prepared was added to IOO cc of cottonseed oil, without coming into contact with the air. Hydrogenation was then carried on a t 240' to 250' C for three hours. After having cooled to room temperaturc, the oil became a very soft solid. Its iodine value was reduced from 109to 84, and its melting point was z 5' C. 2.
Kahlenberg and Ritter: J. Phys. Chem. 25, 89-114 (1921) Fig 3, J. Phys. Chem. 25, 98 (1921)
60
LOUIS KAHLENBERG AND TSU P E I P I
Nickel tungstate catalyst. The method of preparation of the nickel tungstate was practically the same as that of preparing nickel molybdate, sodium tungstate being used in place of sodium molybdate. The nickel tungstate was reduced in hydrogen a t 370' C for three hours. After cooling in a hydrogen atmosphere, it was transferred into IOO cc of cottonseed oil. The hydrogenation was carried on a t 250' to 260' C. At the end of three hours a sample was taken and it was found that its iodine value had changed from 109 to 82, and its melting point had become 30' C. At the end of four hours, its iodine value was further lowered to 52' and its melting point raised to 42' C. 3.
Tungsten oxide catalyst. Pure tungsten trioxide was reduced in a stream of hydrogen a t 400' to 420' C for five hours. It changed from yellow to blue in color. About 5 grams of this catalyst was put into IOO cc of cottonseed oil, and the latter was hydrogenated for three hours at 250' to 260' C. On cooling, the oil did not show any tendency to solidify, and its iodine value was nearly the same as that of the original sample. 4.
Nickel silicate catalyst. To an aqueous solution containing ten grams of nickel chloride, nine and one-half grams of sodium silicate were added to precipitate nickel silicate. The precipitate was washed with warm water until no trace of sodium salts could be detected in the filtrate. The nickel silicate was dried, ground to a very fine powder and then subjected to hydrogen reduction, in a combustion tube a t z~oo-zgooC for three hours. After cooling, it was introduced into IOO cc of cottonseed oil. This catalyst remained suspended more uniformly in the oil than any other catalyst used in the preceding experiments. The hydrogenation was carried on at 180'-200' C for three hours. The iodine value was changed from rog to 40 and the melting point was raised to 44' C. The hardened fat was very white and had acquired an odor quite different from that of the original oil. 5.
Nickel borate catalyst. Nickel borate was prepared in the same way as nickel silicate except that borax was used as the precipitant. The nickel borate was reduced a t 285'290' C for three hours. The oil was hydrogenated in the presence of this catalyst at zoo' C. A sample was taken a t the end of three hours and found to have an iodine value of 60. Originally it was 109. The hardened fat melted at 42' C. This catalyst also remained well suspended in the oil. 6.
7. Iron silicate catalyst. An aqueous solution containing ten grams of sodium silicate was treated with a little more than an equivalent amount of ferrous sulphate in solution. The formation of insoluble ferrous silicate took place instantaneously. The precipitate was washed with hot water until it was entirely free from sulphates, which are commonly believed to be "poisonous" to the activity of a nickel catalyst, After drying and pulverizing, the powder was subjected to reduction
ON THE CATALYTIC HYDROGENATION OF CERTAIN OILS
61
a t 330°-3500 C for three hours. This catalyet was introduced into the cottonseed oil without coming into contact with air. After three hours of hydrogenation, the iodine value of the oil was only slightly lowered, namely from 109to 105. Ferrous tungstate was prepared and tested in the same manner as the silicate. It was found that there was no change in the iodine value of the oil, even after the hydrogenation had been continued for three hours. 8 . Iron-nickel silicate catalyst. T o a sodium silicate solution, an equivalent amount of ferrous sulphate and nickel chloride solution was added to precipitate the combined silicates of iron and nickel. This precipitate was thoroughly washed with hot water , till free from chlorides and sulphates. It was reduced by hydrogen at a temperature of 300' C for three hours. The reduced substance was added to IOO cc of cottonseed oil, and the hydrogenation was conducted at 180' to 200' C. After three hours, the oil was still in a liquid state a t room temperature. The iodine value had changed from 109 to 94. On comparing these resulte with experiment 5 it is evident that the presence of iron greatly ,diminishes the catalytic activity of nickel. '
9. Nickel glycinate catalyst. Five grams of freshly precipitated and thoroughly washed nickel hydroxide were heated in 150 cc of distilled water with about eight grams of glycine until the liquid became perfectly clear. On cooling, nickel glycinate of a sky blue color gradually crystallized out. After being dried, a portion of it was put directly into the cottonseed oil and hydrogen was run into the mixture for three hours a t a temperature of 220'-230' C. There was no appreciable change in the iodine value of the oil as compared with that a t the start. Another portion of the nickel glycinate was reduced below 235' C for three hours (because above that temperature it was found to decompose) and the hydrogenation was repeated in the usual way. The result was again negative.
Nickel tyrosinate catalyst. Nickel tyrosinate was prepared from the amino-acid tyrosine and nickel hydroxide. It was very difficult to keep it in good suspension in the oil. At the end of three hours of hydrogenation, the oil had neither changed its iodine value nor its melting point. IO.
Thorium stearate catalyst. Ten grams of stearic acid were heated with the equivalent amount of potassium hydroxide. T o the solution of potassium stearate thus formed 3.2 grams of thorium chloride in solution were added. The insoluble thorium stearate was washed with hot water by decantation and then transferred to the filter and washed. This thorium salt was reduced a t 140' to 150' C for three hours. The hydrogenation was conducted in the usual manner at 220' to 240' C. After three hours, the oil seemed to have become somewhat thicker. The original iodine value, 109,was lowered to 101. I I.
LOUIS KAHLENBERG AND TSU PEI PI
62
Thorium silicate catalyst. Thorium silicate was prepared from thorium chloride and sodium silicate, and reduced at 340' to 350' C for three hours. The hydrogenation was conducted for three hours at 220' to 240' C. The oil did not show any sign of solidification even when chilled with ice. I 2.
13. Nickel chromate catalyst.
To prepare nickel chromate, a sodium chromate solution was treated with nickel chloride. After the precipitate had been thoroughly washed, dried and pulverized, it was subjected to hydrogen reduction in a combustion tube at 320' C. for but two hours. The catalyst thus prepared was carefully transferred into the tube containing roo cc of cottonseed oil. This catalyst is pyrophoric. It must therefore be kept out of contact with the air. The hydrogenation was performed a t 220' C for three hours. The oil solidified to a white fat at room temperature and this fat melted at 41' C. The iodine value had changed from 109to 6 2 .
Nickel manganate catalyst. Nickel manganate was obtained by precipitation using solutions of sodium manganate and nickel chloride. The precipitate was washed with distilled water as soon as it had been formed, because the manganate on standing easily oxidized to permanganate. The nickel manganate was then reduced a t the same temperature as in the preceding experiment. After three hours of hydrogenation, the iodine value of bhe oil was lowered from rog to 6 2 , and the melting point became 40' .5 C. 14.
Cobalt silicate catalyst. The catalyst was made by treating an aqueous solution of sodium silicate with a cobalt chloride solution. For one portion of the precipitated cobalt silicate, the temperature of reduction by hydrogen was not allowed to exceed 350' C. As a result, at the end of three hours' hydrogenation a t 180' to zoo' C, the cottonseed oil was still found to be a liquid at room temperature. For another portion of cobalt silicate, the temperature of hydroge nreduction was raised to 380°-4000C. With the catalyst thus obtained, the oil solidified on cooling, after having been hydrogenated for the same period of time at 180' to 200' C. The solidified fat melted at 37' .5 C, and had an iodine value of 7 1 . All of the foregoing results are summed up in Table I. IS.
Hydrogenation of Soy Bean Oil with Various Catalysts Nickel silicate catalyst. From experiment 5 , it is evident that nickel eilicate forms the best catalyst for the hydrogenation of cottonseed oil. But when nickel silicate, prepared and reduced in exactly the same way as in experiment 5 , was introduced into a tube containing roo cc of soy bean oil having an iodine value of 130, it exhibited only a very slight catalytic activity, the oil being still liquid 16.
ON THE CATALYTIC HYDROGENATION O F CERTAIN OILS
63
TABLE I Summary of the results of the hydrogenation of the cottonseed oil, whose original iodine value was 109. The time of reduction of each catalyst in hydrogen was three hours, except in the case of tungstic oxide, when it was five hours. The time of hydrogenation was always 3 hours, except in the case of nickel tungstate* when it was 4 hours. ~~
Reduction Temp. "C.
Catalyst
Nickel oxide Nickel molybdate Nickel tungstate
*
11
11
Tungstic oxide Nickel silicate Nickel borate Iron silicate Fe-Ni-silicate Nickel glycinate 19
~
Melt,ing Point after Hydrosenation C.
335-340 3 50-360 37 0 3 70 400-420 290 290 330-3 5 0
2 IO 240-2 jo
63 84
25
250-260
82
30 42
250
'05
300
200
23 5
-
220-230 220-230 2 20-230
94 I09 I09
140-1jo
220-240
350
240
I09 109
320
220
62
320
220
62
3 50
180-200 I 80-2 00
-
11
Nickel tyrosinate Thorium stearate Thorium silicate Nickel chromate Nickel manganate Cobalt silicate Cobalt silicate
Hydrogenation Temp. "C.
~
Iodine Value after Hydrogenation
Z 80-A00
250-260
52
250-260
I09
200
40
2 00
60
109
109
41
liquid 44 42
liquid 19 !9 11 11
7) 1
41 40.5
liquid
71
at room temperature after three hours of hydrogenation. The iodine value was reduced only to 112, no matter how long the hydrogenation proceeded.
17. Nickel borate catalyst. Although nickel borate was not as efficient as nickel silicate in the hydrogenation of cottonseed oil, it worked better in the case of soy bean oil. Nickel borate was prepared and reduced in the same manner as before described. The hydrogenation was conducted a t 200' C for three hours. Solidification of the oil took place with ease a t room temperature. The fat had an iodine value of 78, and a melting point of 33' C. This experiment would indicate that hydrogenation depends on the specific nature of the oil used, as well as on the individual catalyst. 18. Nickel molybdate and nickel tungstate catalysts. These two catalysts were prepared in exactly the same way as before. It was found that at the end of three hours of hydrogenation, neither of the two catalysts had worked satisfactorily. By the use of nickel molybdate, the
'
64
LOUIS KAHLENBERG AND TSU PEI PI
iodine value of the oil was only slightly lowered, namely from 130 to 122. By the use of nickel tungstate, there was no appreciable change in iodine value, even after hydrogenation for six hours. 19. Nickel chromate catalyst.
The method of preparation and the time and temperature of reduction of this catalyst were exactly the same as in experiment 13. The hydrogenation was carried on a t 220' C. Samples were taken and tested a t one hour intervals. The results are given in Table 11.
No. of Hrs. of Hydrogenation
Iodine No. before Hydrogenation
Iodine No. after Hydrogenation
Melting point of the product
I 2
130
105
liquid
130 130 130
74 63
3 4
55
33 41 AA
The color of the hardened fat was not as white as that of the hardened cottonseed oil.
Nickel manganate catalyst. The experiments with nickel manganate were conducted exactly like those with nickel chromate in experiment 19. The result's are given in Table 111. 20.
TABLE 111 No. of Hrs. of Hydrogenation
Iodine No. before Hydrogenation
Iodine No. after Hydrogenation
I
130
I05
2
130 130
72 62
130
53
3 4
Melting point of the product
liquid 34 42
45
Hydrogenation of Various Oils with Nickel Silicate as Catalyst The nickel silicate catalyst was used in the following experiments because it had been found the most efficient one in the work on cottonseed oil.
Olive oil. Pure California olive oil was preheated at 140' C. for an hour before hydrogenation. The nickel silicate, which was prepared as before, was added to the oil. The hydrogenation was conducted at 220' C. for eight hours. Samples were taken and tested a t one hour intervals, and the results are given in Table IV. (The original iodine value of the olive oil was 80). 2
I.
ON THE CATALYTIC HYDROGENATION O F CERTAIN OILS
TABLE IV No. of Hrs. of Hydrogenation
I
Iodine value after Hydrogenation
I
Melting point, of the product
70 68
I 2
liquid 30 32 33
64 60
3 4 5 6
7 8
58
34.5
52
39 39 39
52
52
TABLE V (The iodine value before hydrogenation was No. of Hrs. of Hydrogenation
Iodine value after Hydrogenation
I
113 IO1
2
3 4
'
95 95
II5)
Melting point of the product
liquid 1)
,, 11
65
66
LOUIS KAHLENBERG AND TSU P E I PI
No. of Hrs. of Hydrogenation
Iodine value after Hydrogenation
I 2
138
J,
?7
?I
109 109
6
29
odine value after Hydrogenation
No. of Hrs. of Iodine value aftei Hydrogenation Hydrogenation
-
I
3 4
5
6 7
8 9 IO
I1 I2
I3
9)
I IO
4 5
2
liquid
I
I33 124
3
Melting point of the product
94 78
liquid
65
32
55 51 48 45 41
39 40 41 * 5 43 44 45 46 48.5
38 35 33 32 31
50 :I
11
Melting point of the product
14
30
52
I5
29
53
16
27
54
I7
25
55.5
23 21
57
18 I9
58 59 60 61
20 21 22
I9
23 24 25
I2 I1
62
10.5
26
65
IO.?
I7 I4
64 6
