N ICKEL-CATALYSTS (18) Fletcher, G. C., and Wohlfarth, E. P., Phil. Mag., 42, 106 (1951). (19) Goldman, J. E., Phys. Rev., 82, 339 (1951). (20) Greene, J. B., and Manning, M. F., Phys. Rev., 63, 203 (1943). (21) Griffith, R. H., “Advances in Catalysis and Related Subjects,” Vol. 1, p. 91, New York, Academic Press, 1948. (22) Grube, G., and Jedele, A,, 2. Elektrochem., 38, 799 (1932). (23) Gurney, R. W., Phys. Rev., 47, 479 (1935). (24) Herring, C., and Nichols, M. H., Rev. Modern Phys., 21, 185 (1949). (25) Himmler, W., 2. physilc. Chem., 195, 244, 253 (1950). (26) Hudson, J. C., Trans. Faraday SOC.,25, 177 (1929). (27) Irmann, R., Abhandl. Inst. Metall., Aachen, 1, 39 (1916). (28) Johnson, W. A,, Metals Technol., Tech. Pub. 2007 (1946). (29) Jones, H., Proc. Phys. SOC.(London), 49, 243, 250 (1937). (30) Keesom, W. H., and Kurrelmeyer, B., Physica, 7, 1003 (1940). (31) Lennard-Jones, J. E., Trans. Faradag SOC.,28, 333 (1932). (32) London, F., 2. Physik, 63, 245 (1930). (33) Long, J. H., Fraaer, J. C. W., and Ott, E., J. A m . Chem. SOC., 56, 1101 (1934). (34) McCartney, J . T., Seligman, B., Hall, W. K., and Anderson, R. B., J. Phys. and Colloid Chem., 54, 505 (1950). (35) Manning, M. F., Phys. Rev., 63, 190 (1943). (36) Manning, M. F., and Chodorow, M. I., Ibid., 56, 787 (1939). (37) Matano, Proc. Math. SOC.Japan, 15, 405 (1938). (38) Maxted, E. B., J. SOC.Chem. Ind. (London),67, 93 (1948). (39) Mott, N. F., Phil. Mag., 22, 287 (1936). (40) Mott, N. F., and Jones, H., ”Theory of the Properties of Metals and Alloys,” London, Oxford University Press, 1936. (41) Mulliken, R. S., Phys. REV.,46, 549 (1934); J. Chem. Phys., 2, 782 (1934); 3, 573 (1935). (42) Neumann, B., 2. Elektrochem., 35, 42 (1929). (43) Ogg, R. A., and Polsnyi, M., Trans. Faraday Soc., 31, 1375 (1935). (44) Pauling, L., “Nature of the Chemical Bond,” 2nd ed., Ithaca, N. Y., Cornell University Press, 1940. (45) Pauling, L., Proc. Roy. SOC.(London), A196, 343 (1949).
’
(46) Pilling, N. B., and Bedworth, R. E., IND. ENG.CHEM.,17, 372 (1925). (47) Price, W. C., Chem. Revs., 41, 257 (1947). (48) Procter and Gamble Co., Brit. Patents 562,609, 562,610 (1944); 570,957 (1945). (49) Prosen, E. J. R., and Sachs, R . G., Phys. REV., 61, 65 (1942). (50) Rado. G. T.. and Kaufmann, A. R., Ibid., 60, 336 (1941). (51) Reynolds, P. W.. J . Chem. SOC.,1950, 265. (52) Rideal, E. K., Proc. Cambridge Phil. Soc., 35, 130 (1939). (53) Rideal, E. K., and Trapnell, B. M. W., Discussions Faraday SOC.,8, 114 (1950). (54) Rienlicker, G., and Bade, H., 2. anorg. Chem., 248, 45 (1941). (55) Rienacker, G., and Bomnier, E. A,, Ibid., 242, 302 (1939). (56) Rieniicker, G., and Burmann, R., J . p a k t . Chmn., 158, 95 (1941). (57) Rienacker, G., and Hildebrandt, H., 2. anorg. Chem., 248, 52 (1941). (58) RienLcker, G., Muller, E., and Burmann, B., Ibid., 251, 55 (1943). (59) Rienacker, G., and Sarry, B., Ibid., 257, 41 (1948). (60) Rienacker, G., Wessing, G., and Trautmann, G., Ibid., 236, 252 (1936). (61) Russell, A. S., Nature, 117, 47 (1926). (62) Schuit, G. C. A , , D i s c u s s i o n s Faraday SOC.,8, 204 (1950). (63) Seith, W., “Diffusion in Metallen,” p. 50, Berlin, Julius Springer, 1939. (64) Seitz, F., “Modern Theory of Solids,” New York, McGrawHill Book Co., 1940. (65) Tammann, G., 2. anorg. Chem., 111, 92 (1920). (66) Taylor, A,, and Weiss, J., Nature, 141, 1055 (1938) (67) Taylor, H. S., Proc. Roy. SOC. (London), A108, 105 (1925): J. Phys. Chem., 30, 145 (1926). (68) Twigs, G. H., Discussions Faraday SOC.,8, 152 (1950). (69) Uhlig, H. H., Trans. Electrochem. SOC.,85, 307 (1944). (70) Wagner, C., J . Chem. Phys., 19, 626 (1951). (71) Zener, C., Phys. Rev., 81, 440 (1951).
RECEIVED for review Ootober 17, 1951.
ACCEPTEDFebruary 5 , 1952.
NICKEL COMPOUNDS AS CATALYST RAW MATERIALS JOHN G. DEAN* The International Nickel Co, Inc., New York 5, Several million pounds ,of nickel compounds are used each year in the United States in the production of catalysts, largely for hydrogenation reactions. The inorganic salts serve as reagents for preparing nickel hydroxide and carbonate, which yield on reduction so-called precipitated catalysts. Nickel nitrate is particularly suited for the preparation of impregnated catalysts, while nickel formate is used in making liquid-process Catalysts. Raney nickel, usually derived from nickel-aluminum alloys, is unique in that intermetallic compounds are involved. Costs vary widely with the particular nickel derivatives used, but performance is the main consideration because of the small quantities of catalyst required on a percentage basis in most hydrogenation reactions.
ICKEL catalysts were unknown until just before the start of the present century, when the classical work of Sabatier
N
(86)called attention to their potentialities and opened up vastly important applications. Today, they are possibly the most widely studied of all catalytic materials, as evidenced by the hundreds of scientific articles indexed under this broad topic each year by abstract journals. They conform to the classical definition of a catalyst in that they affect the rate of chemical reactions without being chemically changed at the end of the process. They do not alter the free energy or change the equilibria involved, but Present addresi‘ Dean Researoh Servicea, Tuckahoe, N.
May 1952
Y.
N. Y.
when properly applied can be markedly effective in lowering the energy of activation in specific cases and thus exerting powerful influences on the rates of certain reactions and the actual course of complex chemical processes. The most familiar and b y far the largest application of nickel catalysts is in the hydrogenation of organic materials containing unsaturated carbon-to-carbon bonds (7‘). In this function they belong to the so-called contact type of catalyst as used in heterogeneous systems-i.e., the nickel is present as part of a solid phase, with the catalyzed reaction taking place in liquid and gas phases in contact with the surface of the nickel. The process of fat hardening provides an outstanding example of this type of catalysis. Hydrogen can be bubbled indefinitely without effect into cottonseed oil being heated and agitated in an appropriate vessel, but once a fraction of a per cent of h e l y divided active nickel catalyst is added, a vigorous reaction starts and in a matter of minutes th’e normally liquid oil can be converted to a stable solid, making such products as margarine practical possibilities
(W. The basic problem in the production of nickel catalysts centers around the enlargement and maintenance of the catalyst surface. Nickel compounds play a major role in this operation, serving primarily as intermediates in the conversion of massive nickel of no measurable catalytic activity under most conditions, to higharea, active forms capable of forming transition complexes with
INDUSTRIAL AND E N G I N E E R I N G C H E M I S T R Y
985
NICKEL-CATALYSTS reactants. Although contact catalysts normally remain chemimlly intact a t the end of a reaction, they enter into the process both physically and chemically by functioning as adsorbents and by forming intermediate complexes, These considerations give great importance to surface characteristics and make it essential in most cases to utilize chemical rather than mechanical means in preparing nickel catalysts (10).
TaMe Form of Nickel Electrolytio niokel (SI) Cathodesheets Squares
QM squares
Mond pellets Standard Tr = trace.
Inch X 27 X 36 thick X 1 X 1 , 2 x 2 , 4 x 4, 9 X 9, eto.
v/a-1/z 8/+/z
1/8
x
1
x
1
Primary Nickel in Catalyst Manufacture Nominal Analyses, % Fe
cu
Si
C
8
99.95
0.01-0.04
0.014.04
Tr
Tr
Tr
a
..
..
99.95 99.95
0.01-0.04
0.014.04
Tr Tr
Tr Tr
Tr Tr
..
..
, .
$
99.60 99 70
0.15 0.06
0.025 0.02
0 10 0.10
0 10 0.05
0.005 0.005
..
99.65
0.06
0.02
0.10
0.06
0.03
.. .. ..
$
0.014.04 0.01-0.04
0.03
0.003
Most of the familiar nickel compounds have been investigated a t one time or another as catalyst raw materials, but less than a dozen distinct derivatives now play roles of importance. The three most commonly encountered inorganic salts-nickel sulfate, chloride, and nitrate-serve widely as intermediates or reagents supplying nickel ion. Nickel oxide, hydroxide, basic carbonate, and formate serve as raw materials for the reduction to finely divided active nickel in the final step of catalyst preparation. Certain nickel alloys, notably those with aluminum of the type developed by Raney, contain intermetallic compounds which can be made to yield active nickel by selectively dissolving away the catalytically inactive constituents, leaving the nickel in the form of an alloy skeleton presenting a very large effective surface per unit weight. These particular derivatives serve as raw materials for the bulk of all nickel catalysts now produced and are given preferential attention in this paper. An outline of the chemical steps involved in the use of these compounds for the production of catalysts is given in Figure 1. PRIMARY NICKEL
Primary nickel, as produced in the processing of nickel ores, serves as the basic source of the metal for catalyst production, although substantial quantities are also made from nickel salts recovered as by-products in the processing of ores of other metals, notably those of copper, and from secondary sources of nickel such as spent catalysts and metal scrap (29). The two main processes by which nickel is refined, known as the electrolytic and Mond or carbonyl processes, yield metal of reliable purity in forms that can readily be adapted to catalyst manufacture. The electrolytic process yields cathode sheets which can be used directly in the various sizes available, or in the form of shot prepared by melting the cathode deposits and quenching in water or steam ( I d ) , while the Mond process yields nickel in the form of spherical pellets ( S I ) . The f o r m of primary nickel commonly used are listed in Table I, with typical analyses and an indication of the use in the production of particular derivatives serving as intermediates in catalyst manufacture. NICKEL SALTS O F M I N E R A L A C l D q
Most of the available forms of primary nickel can be dissolved readily in hydrochloric and nitric acids, A common procedure is to add the diluted acids to a large excess of the metal in a suitable corrosion-resistant tank vented to the atmosphere. After the bulk of the initial reaction has taken place, the temperature is gradually raised by heating with steam and the mixture is finally
986
Production Electro Ni(0Hh NE04 NiClt
Ni (fCo)
99.89
J/1s’/r
1.
boiled until the free acidity is reduced nearly to zero. Ten to 20% of the acid is normally volatilized to waste with the wcaping hydrogen in this type of batch technique, but the limited size of the operation in most cases does not usually make thia loss B serious consideration, As the reaction between nickel and sulfuric acid progresses much more sluggishly, it is expedient in the production of this salt to use a form of the metal presenting 5
...
0.04
0.001
*
*
*
..
Use
*.
Ni(NQi)n G . 4 1 *.
. I
..
** *
.. *
a3
..
..
*
..
d
large area. The presence of a small amount of sulfur in the metal also substantially hastens the process, making the special form known as steam-shattered, high-sulfur nickel shot especially suited for the preparation of the sulfate. It is not necessary to isolate the nickel salts from the solutions derived from the reactions between the metal and acids, with the one exception of the nickel nitrate for impregnated catalysts. In this case, the solution is simply concentrated in steam-heated evaporators and crystals of nickel nitrate hexahydrate are harvested in good yield after the concentrate has been atloF-ed to stand 2 days a t room temperature. In the production of the remaining catalysts, the precipitants such as sodium carbonate or sodium formate are mixed ~ i t the h salt solutions after appropriate adjustment of the pH and the concentration. All three of these nickel salts are also geneially available on the market in qualities very satisfactory for catalyst manufacture (8). Typical data on composition and cost are given in Table TI.
Table 11.
Composition and Cost
Formula WIolecular weight Ni content, theoretical, 7% Typical analyses Nickel, % Iron, % Copper, % Zinc, % Cost, $Ab. Salt Contained Ni
(IS) of
Inorganic Nickel
Sulfate hiis04 6HzO 262 85 22 33
Chloride XiClz.6HzO 237 70 24 69
22.25 0,005 0.003
24.5 0.06
Salts
Nitrate Ni(N0s)z 6H2O 290 80
LO 18
20.0 , . I
0.015
0.005 0.02
...
0.268 1.20
0.345 1.39
0.335 1.66
.,.
~~~
NICKEL SULFATE IN PRODUCTION O F PRECIPITATED NICKEL CATALYSTS
Nickel sulfate is used by far in the largest quantities of these three salts largely because it is normally the cheapest and most generally available. The normal procedure is to precipitate nickel hydroxide or basic carbonate from solutions of this salt, often in association with a more or less inert, high-area carrier material such as diatomaceous earth, and then to reduce the precipitate with hydrogen after washing, drying, and grinding (6). This type of product is characteristic of the so-called precipitated, dry-reduced nickel catalysts, which are so widely used for the hydrogenation of organic compounds, particularly in the fat hardening industry. The production of nickel catalysts by this method requires close attention to many variables. Important consideration- are
INDUSTRIAL AND ENGINEERING CHEMISTRY
V d , 44, No. 5
encountered almost a t every step such as in the selection of the precipitant, solution concentrations, temperatures, method of mixing, chemical ratio of reactants, washing procedure, and conditions of drying the precipitate. The basic objective throughout these steps prior to the reduction is to obtain a pure precipitate composed of very minute and reasonably uniform crystals (3). The attainment of this ideal j s much more difficult than it might appear. For example, if 2 N solutions of nickel sulfate and sodium hydroxide are simply mixed in approximately equivalent quantities and the resulting precipitate very thoroughly washed with distilled water to the point that peptization causes difficulties, the dried product may contain over 3% sulfate retained as insoluble basic sulfates and adsorbed or occluded salts. During the washing treatment the crystals of nickel hydroxide have an opportunity to grow, with the result that the reduction step yields a rather limited nickel surface heavily contaminated and poisoned with nickel sulfide. The exact methods used in the industrial preparation of precipitated nickel catalysts have usually been regarded as confidential and have not been widely discussed in the literature. I t now seems evident, however, that the most successful techniques have tended to minimize both crystal contamination and crystal growth. Hot, dilute solutions of nickel sulfate, often of the order of 0.2 N , are commonly used, and it is believed that the best results are obtained when they are added to the alkali present in a second solution in such quantity as to provide a slight overall excess. Nickel hydroxide is substantially less soluble in alkaline solutions in accordance with the solubility product law, and there is evidence that its rate of crystal growth decreases with incr’eases in the pH. On the basis of this reasoning, alkali may be added to the first wash waters while the bulk of the sulfate ion is being removed. Ultimately, however, all excess alkali must be removed from the precipitate, as it exerts a poisoning action on the finished catalyst, possibly due to the formation of compounds such as soaps on the surface of the nickel. Precipitants for Nickel Salts. Sodium, potassium, and ammonium hydroxides, carbonates, and bicarbonates have all been used successfully in the production of precipitated catalysts from nickel sulfate but modern practice has settled conclusively on eodium carbonate and bicarbonate as the dominant precipitants. When these latter alkalies react with nickel sulfate in aqueous solution, voluminous basic nickel carbonates of variable composition are precipitated. When sodium bicarbonate is used, the precipitate may be richer in nickel carbonate, but pure nickel carbonate remains as a laboratory curiosity which can be obtained only by very special procedures ( 2 ) . For example, even if carbon dioside-saturated sodium bicarbonate is used as the precipitant in the cold, the carbon dioxide content of the oven-dried precipitate still falls considerably below the value for nickel carbonate, corresponding closer to 3KiC03.2Ni(OH)z.
Table
111.
Quantities and Relative Costs (75) of Precipitants for Nickel Salts
Cation Sodium Formula Composition Weight, Ib./lb. Ni Price. C/lb. Cost, b/lb. Ni Potassium Formula Composition Weight, Ib./lb. Ni Price, +Ab. Coat, #/lb. Ni Ammonium Formula Composition Weight Ib./lb. Ni Price. &Abs Cost, Ulb. Ni
May 1952
Anion Carbonate
Bicarbonate
KazCOa 58% NazO 1.82 1.6 2.9
NaHCOs 99% NaHCOt 1 44 2.1 3.0
2 OB 7 9 16 4
KaCOs 83% KOH 2 84 6 75 19.2
100% KHCO: 1 7 22 37.4
xH4Off 29 4% NHI 1.97 3 1 6 1
(NHc)zCOa.HaO 31% NH: 2.025 23 46.6
Hydroxide SaOH 76% NazO 1.41 3 35 4.7
KOH
88% KOH
KHC02
NH~HCOI 21 5% NHs 2.69 5.5
14.82
Although accurate data allowing comparisons between the basic carbonates and hydroxide are not available, it seems likely that the pitfalls of adsorption and excessive crystal growth are more easily avoided with the former materials. There is also evidence that the reduction with hydrogen proceeds at a lower temperature, minimizing the danger of partially sintering the nickel and thus reducing its surface area. These advantages,
P
R
Massive
Figure
I
M
A
Precipitated
R
Y
Liquid
N
I
C
K
impregnated
E
L
Alloy Stele+on
1. Chemical Steps in Production of Common Nickel Catalysts
combined with the low cost of sodium carbonate and bicarbonate as precipitants, have given nickel catalysts of this derivation a very firm place in industry. An indication of the quantities of the different precipitants required and their relative cost is given in Table 111,where the figures represent the approximate minimum cost of alkali to precipitate 1pound or 15.45 chemical equivalents of nickel ion. NICKEL CHLORIDE AND NITRATE
Nickel chloride and nickel nitrate can also be used in the production of precipitated nickel catalysts and in some cases give advantages that offset their extra cost. I n both cases, the byproduct electrolytes are more easily removed from the precipitate. I n the case of the nitrate, a further advantage is offered in the elimination of absorbed nitrate by thermal decomposition during the reduction step. This latter consideration definitely gives nickel nitrate the preferred position among the nickel salts in catalyst manufacture whenever the added cost can be justified (24). Nickel Nitrate. Nickel nitrate is unique in that the hexahydrate, Ni(N03)2.6HI0, melts or dissolves in its own water of crystallization at about 55’ C. On further heating in air, it gives off first some water of hydration, yielding a very concentrated melt, and then starting at about 105’ C., it evolvw a mixture of water vapor and oxides of nitrogen, yielding ultimately a very finely divided residue of nickel oxide, NiO, which yields active nickel catalyst on reduction with hydrogen (IC). This unusual confluence of properties has led to the development of the very useful so-called impregnated type of nickel catalyst. In the’preparation of this type of catalyst, a preformed porous
INDUSTRIAL AND ENGINEERING CHEMISTRY
1
987
NICKEL-CATALYSTS support material is simply impregnated with molten nitrate, gently ignited, and then reduced frequently in the course of actual use. Catalysts of this type are uniquely suited to vapor phase reactions involving hydrogen transfers such as the hydrocarbonsteam reaction (13). ELECTROLYTIC NICKEL HYDROXIDE
Nickel hydroxide of suitable quality for use in the manufacture of nickel catalysts can be produced directly from metallic nickel in a spccial electrolytic cell without recourse to nickel salts as intermediatas. The general procedure is to apply low-voltage, high-amperage direct current to a cell equipped with standard electrolytic nickel sheets as anode and nickel or other corrosionresistant metal as cathode and containing 1 to 5% sodium chicride solution as electrolyte. The following reactions take place: 2Hz0 2e = 2SaOH H, Cathode 2Na+ Anode 2C1Ni = NiCl2 2e Net result Ni 2He0 = Iii(0H)z Hf
+ +
+ +
+
+
+
Although the sodium chloride electrolyte is theoretically selfregenerative, a small amount of basic nickel chloride is precipitated along nith the nickel hydroxide and the electrolyte tends to become excessively alkaline unless action is taken to control the pH, such as by bubbling carbon dioxide through the cell. Diatomaceous earth or other catalyst carriers can be incorporated in the nickel hydroxide by simply suspending it in the electrolyte during the precipitation process. Catalysts prepared by this technique are very active and have highly reproducible properties. l'hey are currently used to some extent in the fathardening industry (16, W ) . NICKEL F O R M A T E
Nickel formate, as in the case of nickel nitrate, exhibits unique behavior under pyrolysis which makes it useful &s a reagent in catalyst production. When the salt, which normally occurs as the dihydrate, Ni(E[C00)2.2H20,is heated, it first gives off water of hydration starting a t about 140' C., and then at about 210" C. the anhydrous salt starts to decompose with the evolution of a gas mixture composed mainly of carbon dioxide, hydrogen, and water. A finely divided, unsintered pure nickel residue with very active catalytic properties ultimately makes up the solid residue. The equation for the main reaction is as follows: Ni(HC00)t.2Hz0 = Xi
+ 2C02 + €I2 + 2H20
In the industrial production of cataly3ts of this type, which are used primarily for fat hardening, the usual practice is to suspend 1 part of nickel formate dihydrate in 2 to 4 parts of oil of the type t o be processed in a reaction vessel equipped with an agitator, and then heat the mixtuic nhile bubbling in a slow Table IV.
__
Catalyst Derivation
Organic salt NiS04 NaOOCH NiSOi NazCeOc Impregnated Ni(N0s)z Alloy 50% Ni-SO% A1
++
42% Ni-58% 30% N1-70%
a
Af
Al
stream of hydrogen primarily to sweep away the evolved gase5. The temperature is usually not allowed to rise above 240" ( 2 . and the decomposition process is normally complete in about 1 hour. Diatomaceous earth can then be incorporated and the mixed suspension used directly in the hydrogenation of oil,s, or the mixture, which is solid at atmospheric temperatures, can be cast into blocks or formed into flakes on a chill roll. The catalyst can also be transferred to other liquids without loss of activity as long as it is not exposed to oxidation (32). Sickel formate is prepared commercially by metathesis between nickel sulfate and sodium formate (9) or by reaction of nickel hydroxide with formic acid. I n the former case, the reaction takes place readily when a strong, hot solution of nickel sulfate and a solution of sodium formate, brought to the neutral point with formic acid, are mixed in equivalent quantities. The concentration is adjusted just below the point where sodium sulfate starts to precipitate (37-38' Be.) and the nickel formate is collected by filtration from the hot solution. The crystals are washed with cold water and dried below 100"C. They tend to retain sulfate ion, and when this impurity is considered objectionable, the direct reaction between nickel hydroxide and formic acid may be preferable. NICKEL O X A L A T E
Nickel oxalate exhibits behavior very similar to nickel formate under pyrolysis, decomposing mainly in accordance with the following reaction: NiCz04.2H20 = Ni 2C02 2&0
+
The water of hydration starts to escape at about 150" C., followed by the liberation of carbon dioxide containing a trace of carbon monoxide a t about 200" C. The residue is mainly pure nickel, although i t may contain small amounts of nickel oxide and nickel carbonate if the decomposition is not carried out in a reducing atmosphere ( 1 ) . Nickel osalate is singularly easy to prepare in high yield by metathesis between nickel sulfate and sodium oxalate and the catalysts produced from it are interchangeable with those from the formate. It has not been widcly used in the industrial production of nickel catalysts, however, because of the higher cost of the oxalate. Sodium oxalate, for example, costs about 50% more per chemical equivalent than sodium formate, leading to an extra reagent cost of about 7 ccnts per pound of nickel catalyst. NICKEL ALLOY CATALYSTS
Iniermetallic compounds of nickel with certain elements which can be selectively dissolved awag, such as aluminum, siliron, magnesium, and zinc, can under controlled conditions yield very active nickel catalysts presenting a very large area in the form of an alloy skeleton. Catalysts of this type were patented by Rnney in 1925 (19-22) and today are very widely known as Raney nickel. Although many cornbinations of elements have h c n
Required and Costs (75) of Reagents for Preparing (CAlciilated theoretical minimilin per poiind contained nickel)
Quantities
Sic1ic.l
~.
+
Intermediate
N i c k e l Catalysts Preciuitantr
$Ab.
'Totit1
$/lb. Ni
(lost. B;'T,b. Ni
Type
Silb. Si
Sheets, eiectro Shot, mnhigh-S Shot, 9 s . high-8 Shot, ss. high-S Shot, ss. h i g h 4
0 57 0 61 0 61 0 61 0.61
Sac1 and COz as HzSO4, 93%, 66' HzSOa, 93%, 66' HzSO4, 93%, 66' IIC1, 31.5%, 20'
0.021
0.021 0.027
O.'d38 0.038 0.038 0.106
Squares, eleotro
0,;s
R S O s , 52.370, 3 6 O BB., 4.11 lh. a t 0.05
0 206
NaiCOa, 58% Piano, 1.821b. at0.016
0.029
0.82
Shot Shot:
high-S high-S
0 61 0.61
IJ?SO4, 03%, G 6 O BB., 1.79 Ib. at 0.021 IlpS01, 93%. 6 6 O BE., 1.70 lb. a t 0.021
0.038 0.038
NaOOCH, 100%. 2.32 lb. a t 0.071 NanCzOa, 10096, 2.28 lb. a t 0.105
0.165 0.239
0.81 0.89
Squares, electro
0.58
ITNOS, 52.3%, 36O BQ.,4.11 lb. a t 0.05
0.206
Iione
...
0.79
Shot Shot Shot
0.60 0.60 0.60
AI, 1 lb. 1.38 lb. a t 0.18 lb. a t 0.18
0.18
NaOH, 76% NaaO, 1.48 lb. a t 0.0335 NaOH 76% IiazO 2 04 lb. a t 0.0335 NaOH: 76% NazO: 3:44 lb. a t 0.0335
0.049
N ,2.33
0.83 0.03 1.14
sq 8s:
Reagents electrolyte BB 1.79 lb. Be:: 1.79 lb. BB., 1.79 Ib. BB., 3.84 Ib.
Reagents
Ni
at at at at
0.021
0.25 0.42
0.080 0.115
Steam-shattered.
988
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 44, No. 5
NICKEL-CATALYSTS studied, industrial use is very sharply limited to nickel-aluminum source of the metal. All chemicals for the production of interalloys of the following approximate compositions: 50y0 nickelmediates are by-passed with the use of electric power in producing 5070 aluminum for powdered catalysts and 42% n i ~ k e l - 5 8 ~ ~ the nickel hydroxide. The cost of electric power will, of course, aluminum for lump catalysts. Alloys in this concentration vary widely with the location and consumption position of a parrange are readily prepared by working shot nickel into the ticular producer, but it seems evident that it should never become requisite quantity of molten aluminum heated to 900’ to 1200’ C. a large factor. A small variable consumption of materials in preparing and maintaining the electrolyte, such as sodium chloand protected from surface oxidation by a salt flux or an inert atmosphere (18). ride and carbon dioxide, has been omitted from the calculations, but this is believed to be a very minor factor. The specialized know-how involved in the successful handling of such an electrolytic process has undoubtedly been a major factor in curtailing Table V. Estimated Quantities of Nickel Derivatives Used in the broad use of catalysts of this derivation. Production of Common Catalystsa Catalysts derived from nickel sulfate precipitated with sodium Hydrogenation HydroFats carbon- Ammonia carbonate or bicarbonate involve only slightly higher costs for Nickel Derivatives by and OrSteam-Air Dissocireagents and are the most widely used in industry. The higher Types of Catafysts oils ganics Reactions tion Miso. Total cost of nickel nitrate restricts its use largely to impregnated MasRive Ni shot, pellets, catalysts where the carrier material is a major factor in the etr .. S . s Precipitated over-all cost. Nickel formate and Raney nickel, while involving Ni hydroxide, reagent costs comparable to those for nickel nitrate, are widely electro. s .. . s Ni hydroxide and used because of the advantages they offer in the activation step. basic oarbonate S L from NiSOa Nickel formate can be converted directly to active nickel by heatNi hydroxide and ing in a liquid process, and Raney nickel is readily activated by basic carbonate from NiClp and leaching with alkali and washing in a simple batch operation. S Ni( NOS) z Organic salt .. Ni formate Impregnated M Ni nitrate Alloy 50% Ni-507 .A1 . L .. .. S L 42% Ni-58‘% AI .. S .. . s Totals L L lii. s s .. a Estimated uantities used per year in U.S.A. in lb. of contained Ni. S = un%er 100,000 Ib. M = 100,000 t o 300,000 lb. L = over 300,000 Ib.
.
The intermetallic compounds formed between nickel and aluminum have been thoroughly studied (6) and it is believed that NiAL and Ni2Als are most effective in yielding an active nickel catalyst, while NiAl is virtually inert. The usual activation treatment consists of digesting the sized alloy in hot 20 to 30% sodium hydroxide solution and then washing ( 4 , I?‘). Much of the aluminum present in the form of NiAla and NizA13goes into solution, leaving a high-area pyrophoric nickel sludge, while that present as NiAI remains virtually unaffected. Nickel catalysts of this type are very active and have exhibited general usefulness in most types of organic hydrogenation reactions (26). The equipment required for activating the catalyst is relatively simple, the product suffers only a relatively slow decrease of activity when stqred under water, alcohol, and other organic liquids, and it exhibits highly reproducible properties from batch t o batch. I n normal times perhaps a third of all nickel catalysts used in industry are of the Raney or alloy type. REAGENT COSTS FOR DIFFERENT NICKEL CATALYSTS
The basic costs of producing nickel catalysts vary over a considerable range and depend on many factors not apparent in the final specifications. Reagent costs, although they may vary considerably from one producer to another, are a fairly definite item a t any given price level and provide some clue as to the relative costs of catalyst nickel in different forms. Calculated figures for the theoretical minimum quantities of reagents required for the processing of nickel in the different methods which have been described, excluding the final reduction step with hydrogen and all adjuncts such as promoters and carriers, are given in Table IV. These figures show a variation of about 100% in the minimum cost of reagents, starting a t a level very close to the base price for primary nickel. Electrolytic nickel hydroxide a t 61 cents per pound of contained nickel stands out as the lowest cost material in this list. In this case standard uncut electrolytic sheets of nickel as produced in the electrorefining of nickel serve as the
May 1952
QUANTITIES O F NICKEL COMPOUNDS USED
Nickel catalysts of three main types derived from nickel sulfate precipitated as nickel hydroxide or basic carbonate, nickel formate, and the 50-50 nickel-aluminum Raney alloy constitute the bulk of all those used. Although accurate production figures are not available, it is known that well over a million pounds of nickel are consumed in catalytic applications each year in the United States; the best estimates suggest that over 300,000 pounds of the metal, or the correspondingly higher weights of the specific derivatives, find their way into each of the three main types of catalysts. Impregnated catalysts based largely on nickel nitrate occupy an intermediate position with consumption ranging from 100,000 to 200,000 pounds of nickel each year, while none of the remaining types exceeds 100,000 pounds. Approximate estimates of the quantities used in each type of catalyst, subdivided by main fields of application, are given in Table V. Catalytic nickel plays a role in the chemical process industries which far transcends in importance the modest quantities involved-for example, over a billion pounds of fats and oils are hydrogenated @8), many millions of pounds of valuable organic compounds are synthesized (XI), and billions of cubic feet of hydrocarbon gases ($3) are processed each year in the Unifed States over nickel catalysts. In many cases both the weight and value of the product exceed by as much as a thousand times the weight and cost of the nickel employed as catalyst. The particular nickel compound in catalyst production, therefore, is finally selected largely on merit as determined by the performance of the finished material under actual operating conditions. LITERATURE CITED
(1) “Abegg’s Handbuch der anorganischen Chemie,” Vol. IV, Sect. 111, Part IV, Monograph I, pp. 445-8, Leipzig, S. Hirzel, 1937. (2)Ibid., pp. 637-8. (3) Adkins, H.,“Reactions of Hydrogen with Organic Compounds over Copper-Chromium Oxide and Nickel Catalysts,” pp. 15-19, Madison, Wis., University of Wisconsin Press, 1937. (4) Adkins, H.,and Billica, H. R., J. Am. Chem. Soc., 70, 6958 (1948). (5) Alexander, W. O., and Vaughan, N. B., J. Innst. Metals, 61, 247-63 (1937). (6) Bailey, A. E., “Industrial Oil and Fat Products,” pp. 58991, New York, Interscience Publishers, 1945. (7) Berkman, S.,Morrell, J. C . , and Egloff, G., “Catalysis,” pp. 815-24, 856-64, New York, Reinhold Publishing Corp., 1940.
INDUSTRIAL AND ENGINEERING CHEMISTRY
989
NICKEL-CATALYSTS (8) Chemical IndustTies, Buyers’ Guide Section (October 1950). (9) Ellis, C., U. S. Patent 1,482,740 (Feb. 5 , 1924). (10) Griffith, R. H., “Mechanism of Contact Catalysis,” pp. 1-77, London, Oxford University Press, 1946. (1.1) Groggins, P. H.. “Unit Pi’ocesses in Organic Synthesis.” pp. 514-31, New York, hIcGraw-Hill Book Co., 1947. (12) International Sickel Co. of Canada, Ltd., Can. Mining J . , 67, 457-62 (1946). (13) Komarewsky, V. I., and Riesz, C. H., “Catalytic Reactions” in “Technique of Organic Chemistry,” Vol. 11, “Catalytic, Photochemical and Electrolytic Reactions,” p. 2, New York, Interscience Publishers, 1948. (14) hlellor, J. K,, “Comprehensive Treatise on Inorganic and Theoretical Chemistry,” Vol. XV, pp. 487-90, London, Longmans, Green &- Co., 1936. (15) Oil Paint Drug Reptr., 160, No. 3 (July 16, 1951). (16) Paterson, W. J. (to Lever Brothers Co.), U. S.Patent 2,123,342 (July 12, 1938). (17) Pavlic, A. A., and Adkins, H., J . A m . Chem. SOC.,68, 1471 (1946). (18) Raney, M., IND.ESG. CHEX, 32, 1199-203 (1940). (19) Raney, M., U. S.Patent 1,563,587 (Dec. 1, 1925). ( 2 0 ) Ibid., 1,628,190 (May 10, 1937).
(21) (22) (23) (24) (25) (26)
(27) (28) (29) (30)
(31) (32)
Ibid., 1,915,473 (June 27, 1933). Ibid., 2,139,602 (Dec. 6, 1938). Reed, R. M a ,Trans. A m . Inst. Chem. Engrs., 41, 453-62 (1946). Rideal, E. X., and Taylor, H. S., “Catalysis in Theory and Practice,” pp. 240-2, London, Macmillan Co., 1926. Sabatier, P., and Senderens, J. B., A n n . chim. phus. (8),4, 319 (1905). Schroter, R . , “Reductions with Raney Nickel Catalysts” in “Newer Methods of Preparative Organic Chemistry,” pp. 61-101, Kew York, Interscience Publishers, 1947. Sieck, W., Jr., U. S. Patent 2,054,899 (Sept. 22, 1936). C. S. Bureau of Census, Washington, D. C . , “Statistical Abstract of the United States-1950,” p. 6??, 1950. E. S.Dept. of Interior, Washington, D. C., Minerals Yearbook, 1948,” PP. 882-92, 1126-8, 1950. U. S. Tariff Commission, “Synthetic Organic Chemicals, United States Production and Sales 1947.” Wickenden, T . H., “The Kickel Industry,” in ”Metals Handbook,” pp. 1025-7, Cleveland, American Society of Metals, 1948. Wurster, 0. H., IND. Exc. CHEM.,32, 1193-9 (1940).
RECEIVED for review October 17, 1931.
ACCEPTEDJanuary 19, 1952.
ICKEL CATALYSTS In Hydrogenation o f f a t s and A.
Oils
E. BAILEY
The HumKo Co., Memphis, Tenn. The amount of nickel used as a catalyst for oil and fat hydrogenthe United States it is estimated as ation is relatively small-in 500,000 to 1,000,000 pounds annually. However, i t is a highly essential material, as each pound of nickel accounts for the hydrogenation of 2500 to 5000 pounds of oil, and as a catalyst nickel has no present substitute. The edible fat industry in this country is particularly dependent upon the hydrogenation process because of the great demand for plastic fats, which must be supplied in large part b y processing liquid coktonseed and soybean oils, A review i s presented of the history and technology of hydrogenation and catalyst manufacture and utilization: The finer points of the latter are intimately related to certain distinctive chemical and physical properties Qf fats, which are also briefly discussed.
HE very nature of catalytic action is such that any material used as a catalyst in an industrial process plays a role quite out of proportion to its amount or its value for ordinary purposes. The essential character of a number of specific catalytic materials in the so-called chemical industries is a matter of common knowledge. Outside these, there is perhaps no instance of a large industry so highly dependent upon a small quantity of a single material as is the fats and oils industry upon nickel as a catalyst for hydrogenation. The unique position of nickel in this case is due in part to the very great importance of the hydrogenation process in oil and fat technology, and in part t o the circumatance that for fatty oil hydrogenation nickel has, BO far as present knowledge is concerned, no satisfactory substitute. Essentially, hydrogenation is a process for hardening fats or oils by converting relatively unsaturated and low melting glycerides to higher melting and less unsaturated members and a t the same time conferring upon the fat increased stability toward atmospheric oxidation (the chief cause of fat spoilage) through reduction or partial reduction of the double bonds which comprise its reactive centers. As such, it finds its greatest use in the processing of edible fats, although i t is likewise a key process in the manufacture of certain nonedible fat products. 990
The importance of hydrogenation in the edible oil and fat in dustry is evident from the statistics on the production and consumption of food fats in the United States which are summarized in Table I. Of the five major classes of edible fat products, shortening and margarine, which are made almost exclusively from hydrogenated oils, together account for approximately one third of the total fat consumed. I n addition, there is a considerable production of lard which has been hydrogenated to a slight degree, andmost of the remaining lard is now marketed with the inclusion of 4 t o 8% of highly hydrogenated lard “flakes” added as a stiffening agent. Outside the edible industry, there are very substantial, though unrecorded, production and consumption of hydrogenated fats in the manufacture of soaps, commercial fatty acids, and other products. Taking into account all factors, it is probably conservative to estimate the current output of hydrogenated fats in this country as in the neighborhood of 2.5 billion pounds annually. Large quantities of hydrogenated fats are produced in Europe, where the shortening industry is relatively undeveloped, but where the margarine industry is correspondingly larger, as well as in most of the other industrialized regions of the world. Table 1.
Domestic Disappearance of Food Fats in the United States during the Year Beginning October 1950 (Million pounds, Butter ( f a t content) Margarine ( f a t content) Lard Shortening Edible oils Total
4) 1250 814 1940 1423 1265 6692
-
~~~~
I n common hydrogenation practice catalyst equivalent to 0.05 to 0.10% nickel on the basis of the oil is used for edible fats; somewhat more is usually required for inedible stocks. There is ~ o m re-use e of catalysts; hence the over-all consumption of nickel amounts probably to 0.02 to 0.04%, or 500,000 to 1,000,000 pounds of nickel yearly for the 2.5 billion pounds of oil referred to
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 44, No. 5
