NICKEL-CATALYSTSpound is hydrogen itself, cobalt carbonyl rather than nickel carbonyl is the catalyst. For these reactions, as for the acrylate synthesis with acetylene, the catalyst appears t o be a complex such as nickel iodotricarbonyl. Nickel carbonyl alone is ineffectual but in the presence of halides its reactivity increases as the series progresses from fluoride t o iodide. This supports the view that the active catalyst is a deformed complex containing one or two halides, because the largest deformation of the original carbonyl tetrahedral structure has been effected with t h e largest halide ions as they are the strongest coordinators. It is most probable that the nickel halide complex, tetraiodo nickel, is planar. If this is the case, the
The reactants, whose electronic formulas are listed below, have in common the ability t o share electrons with the nickel atom which needs them to complete its coordination sphere-the acetylene through its triple bond, the ethylene through its double bond, and the ether through its oxygen atom.
H
H:C: ::C:H Acetylene
H
H H
*.
*.
H : C : :C:H Ethylene
H
..O ..
H
This similarity must explain the success of the nickel iodocarbonyl catalyst in effecting the reaction of carbon monoxide with these three widely different materials. ACKNOWLEDGMENT
The helpful discussions with J. P. Brusie, L. E. Craig, R. E. Dial, D. L. Fuller, S.T. Gross, and H. B. Hass of General Aniline & Film Corp. and with J. C. Bailor of the University of Illinois are gratefully acknowledged. /
,
’
L ,
j d
Figure 7.
Y
\
’
Adsorption of Propynol on Nickel
entrance of one or two iodine atoms into a tetrahedral nickel carbonyl complex will greatly distort it. It seems likely that this distorted hybrid structure, neither planar nor tetrahedral, is the catalyst for these syntheses. Adipic Acid. Carbon monoxide, by means of the same catalysts used for the acrylic and carboxylic acid syntheses, will also react with ethers. The synthesis t h a t Reppe was especially interested in was that of adipic acid. Tetrahydrofuran was reacted with carbon monoxide and water at the somewhat more drastic conditions of 270” C. and 200 atmospheres of carbon monoxide to produce adipic acid and valerolactone and valeric acid as by-products (6).
LITERATURE CITED (1) Cope, paper presented before the 12th Natl. Organic Chemistiy Symposium, Division of Organic Chemistry, A 4 ~ CHCM. . SOC.,
Denver, Colo., June 1951. (2) Copenhaver and Bigelow, “Acetylene and Carbon Monoxide Chemistry,” New York, Reinhold Publishing Corp., 1949. (3) Xleinschmidt, R. F., U. S. Patent 2,542,417 (1951). (4) Lippincott, E. R., Lord, R. C., and McDonald, R. S.,tech. repts. 1 and 2 of Contract N5,,1-07810, Spectroscopy Laboratoxy, Mass. Inst. Technol., 1950. ( 5 ) Pauling “Nature of the Chemical Bond,” Ithaca, N. Y . ,Cornell University Press, 1948. ( 6 ) Reppe, J. W., “Chemie und Technik der Acetylen-DruckReactionen,” Weinheim, Germany, Verlag Chemie, G.m.b.H., 1951. (7) Reppe, J. W., PB Rept. 18852-s (1949). (8) Reppe, Schlichting, Klager, and Topel, Ann., 560, 1 (1948). RECEIVED for review October 17, 1961. ACCEPTEDN a r c h 8, 1952.
NICKEL CATALYSTS FOR HYDROCARBON-STEAM REACTION M. R. ARNOLD, KENTON ATWOOD, H. M. BAUGH, AND H. D. SMYSER The Girdkr Corp., Louisville, K y . T h e work reported here is part of a program of detailed laboratory investigation on the properties of catalysts for the reaction of hydrocarbons with steam. The program, which is being continued, will include investigation of the surface area, porosity, pore size, and particle size of the catalysts. Most of the experimental work relating to the life and activity of the catalysts was conducted in semimicro reactors. Results show that, in general, the catalysts with higher nickel contents have higher activities. The exceptions indicate, however, that other factors are important in determining catalyst activity. Rapid inactivation of the commercial catalysts takes place above 1900 F.
HE majority of the many catalysts which have been proposed for the reaction of hydrocarbons with steam have contained nickel as the principal active constituent. Mond and Langer ( 7 ) made hydrogen in 1888 by passing coal gas and steam over re-
T
May 1952
duced nickel or cobalt supported on pumice. Dieffenbach and Moldenhauser ( 3 ) suggested use of wire gauzes of nickel, cobalt, etc., as catalysts in 1909, and Rfittasch and Schneider (6) produced hydrogen (1915) by reacting methane and steam over a nickel catalyst supported on a refractory such as magnesia. I n 1930 the Standard Oil Co. of New Jersey installed a large plant at Bayway, N. J., using nickel catalysts for the methanesteam reaction, A larger plant t o produce hydrogen for t h e hydrogenation of petroleum was started b y the same company in 1931 a t Baton Rouge, La. Plants producing hydrogen for t h e same purpose were installed prior t o 1940 a t Port Arthur, Tex., Richmond, Calif., and Whiting, Ind. (8). I n 1940 the Hercules Powder Co. a t Hercules, Calif., completed a plant t o use natural gas and steam as a source of hydrogen for ammonia synthesis ( 2 ) . By 1946 seven plants with a total capacity of 3 billion cubic feet per month, about three fourths of
INDUSTRIAL AND ENGINEERING CHEMISTRY
999
NICKELCATALYSTS the hydrogen then produced by the reaction of hydrocarbons with etearn over nickel catalysts, were using hydrogen from natural gas for ammonia synthesis (9). In 1949 about 40% of the hydrogen for ammonia synthesis was produced from methane and steam (2), whereas today over 80% of the American capacity for synthetic ammonia is or soon will be in thirteen plants using this reaction over nickel catat) sts
WATER SUPPLY
EXPERIMENTAL
HEATER
n
REACTOR TUBE
CONSTANT TEMPERATURE BATH
{
The semimicro reactor, constructed of '/(-inch Ascoloy pipe. was mounted vertically in an electrically heated furnace. h bundle of six reactors could be placed in each furnace. The center of the catalyst bed, which was 1 1 / 9 inches long, was a t the center of a furnace tube 19 inches long. The catalyst was supported by a thermocouple well, and temperatures were read a t the bottom of the catalyst bed. A ll/*-inch diaspore bed was used for preheating the gases. A schematic diagram of the apparatus is shown in Figure 1. The saturator was adjusted to give an inlet gas consisting of 2.5 volumes of steam per volume of dry gas. Catalysts were reduced for 18 hours a t 1500" F. with hydrogen entering the saturator a t a rate of 5 liters per hour. -4fter reduction hydrogen was replaced with methane and gas samples were taken after methane had flowed for 3 hours Analyses were made by the Orsat method
% reaction
if
a
the surface area, porosity, pore size, and particle size of the catalysts. In order to conserve time and amounts of test gases much of the experimental work has been conducted in semimicro reactors. As a result of the reduced part'icle size and improved heat transfer in the small reactors, the reported catalyst activities are very much greater than those obtainable with present commercial equipment.
=
METER THERMOCOUPLE PREHEAT MATERIAL CATALYST
Figure I .
Semimicro Apparatus
% theoretical reaction
=
(-Gat
yo reaction equilibrium
) 100
These formulas are valid since carbon deposition was negligible. A t 1300" F., per cent reaction a t equilibrium is 94; a t 1400" F., 99; and a t 1500" F., 99.7. At, temperatures above 1500" 1'. per
As a result of the conversions noly in progress in the synthetic ammonia industry more hydrogm soon will be produced in the United States bv reacting- hydrocarbons with steam over nickel " catalysts than will be produced by all other methods combined. Table 1. Blank Tests on Reactors Containing Diaspore Hydrogen from hydrocarbons, exclusive of that used in ammonia Per Cent of synthesis gas, is produced for use in methanol synthesis, the Temp., Material of Space Theoretical F. Construction Velocityu Reaction hydrogenation of vegetable oils, the hydrogenation of petroleum, 1600 Ascoloy 20,000 0.9 and other hydrogenations and syntheses. The Bureau of Mines 1500 Inconel 20,000 0 .3 1700 Ascoloy 20,000 3.7 has operated a pilot plant ( 1 ) producing synthesis gas for the 1700 Inconel 20,000 L.5 Fischer-Tropsch reaction by the reaction of natural gas with 1700 Ascolor 2,000 i 1700 Inconel 2,000 7.2 steam and carbon dioxide over nickel catalysts, and this process 1700 Ceramic 1,080 7.2 may have industrial application in the future. e Theor. vol. Hw'vol. catalyst./lir., r o o ~ nt e m p . and pressure. It is estimated that about 400,DOO pounds per year of nickel catalysts would be required to keep the production of hydrogen for all purposes from hydrocarbons and steam a t the present volume. This represents a nickel consumption of about 80,000 pounds per year. Commercial nickel catalysts used in this country for the hydrocarbon-steam reaction are either supported on a refractory material or compounded and shaped by either extruding or tableting. The supported catalysts are in the form of irregular lumps. and cornpounded catalysts are prepared as rings and cylinders. The various commercial catalysts have approximately equal dimensions of length, width, and thickness, and range from '/z to ll/z inches in size. The nickel contents are between 4 and 30%. The compounded catalysts generally have a higher nickel content, higher activity, and a longer life than do supported catalysts. The supported catalysts are extremely rugged physically but are susceptible to carbon deposition, particularly a t low temperatures. While the compounded catalysts may be made to have great physical strength, they may be subject to considerable shrinkage on use unless they have been preshrunk. Commercial catalysts are generally used at temperatures between 1300" and 1800" F. and a t pressures between atmospheric and 15 pounds per square inch gage. 40,000 10,000 20,000 30,000 The experimental work herein reported is part of a program SPACE VELOCITY of detailed laboratory investigation on the properties of catalysts for the reaction of hydrocarbons with steam. The program ie Figure 2. Activity of Various Commercial Catalysts at 1500" C. being continued, and incompleted work includes investigation of 1000 INDUSTRIAL A N D E N G I N E E R I N G C H E M I S T R Y Vol. 44, No. 5 J
NICKEL-CATALYSTS cent reaction and per cent theoretical reaction are essentially equal. Equilibrium between the product carbon monoxide?carbon dioxide, and hydrogen and the unreacted water is established over the catalyst a t reaction temperature, and the cold product gas retains the high carbon monoxide to carbon dioxide ratio established a t the high temperature (IO). Space velocity is defined as the volume of hydrogen theoretically produced, assuming all the methane is converted t o carbon dioxide and hydrogen, per volume of catalyst per hour a t room temperature and pressure. The catalyst volume, which was usually 1 cc., was calculated from a measured weight of the catalyst (16-20 mesh) and the apparent density determined on a large volume of the material. For the test on the effect of high temperature on catalyst activity, reactors were ceramic tubes, 33 inches long and 1-inch inside diameter. The catalyst (75 cc., 4-8 mesh) was supported by an inverted porcelain crucible which was held in place by the ceramic thermowell. The results of blank tests on various semimicro reactors are shown in Table I. These reactors were loaded with 2 cc. of 16-20 mesh diaspore. In spite of the large surface to volume ratios of the small reactors all the blanks were relatively small. Although Ascoloy tubes (stainless steel, Type 446) were selected because of the low nickel content, an Inconel tube showed a very low blank. Analyses of nine commercial catalysts are given in Table 11, and the results of initial activity tests on these catalysts are presented in Table I11 and Figures 2 and 3. Metals are expressed as oxides, though they are not necessarily present as such. All the catalysts were reduced in the normal manner except No. 1, which was reduced by dry hydrogen since steam and hydrogen appeared to reduce the initial activity. No. 7, which is high in nickel but rather inactive, is not nearly so porous as the other materials. Catalyst 2b, which shows the highest activity, was preshrunk and reduced during preparation. Table IV and Figure 4 show the effect of nickel content on the initial activity of catalysts similar to either No. 1 or 2 in every respect except the proportion of nickel to the other constituents. It may be noted that one of these catalysts deposited on a carrier has about the same activity as an extruded catalyst containing approximately the same amount of nickel. Table V and Figure 5 give the effect of temperature on the initial activity of catalyst No. 1. There is approximately a five' fold increase in activity between 1300' and 1500' F. Although catalyst activity increases rapidly with temperature, inactivation will occur with exposure to a high temperature. A reactor containing catalyst No. 2 a t 2100" F. was plugged with carbon after methane and steam had been passed through it for
Table
11.
Principal Constituents of Catalysts Biilk ...-~ ~
_.
Constituents, % NiO AlzOa SiOz MgO FezOa CaO
Catalyst
No. Type 1 On a carrier
Sample
Nia
6 . 0 80.6 24.1 20.9 29.1 19.5 20.0 2 6 ' 5 24.3 4 11.4 7.7 14.7 11.0 20.0 25.6 6 j 27.7 24.5 7 On a carrier .. Present in combined state, except sample 2b.
Table
10,000 15,000 20 000 25'000 30'000 35 000 40,000 a
4.7 18.9 23.3 27.6 20.0 9.0 11.5 15.7 21.8
10.5 21.2 5:3 19.8 5.0 20.3 5.1 3 2 . 6 12.6 9.6 1.4 7.6 0.2 15.3 9.1 35.4 11.1
1.3 1.0 0.9 0.9
1.0 1.4 1.4 3.4 0.0
167 15.6 15.9 1.2 36.1 31.0 10.4 1.8
Ill. Initial Activity of Catalysts at Various Space Velocities at 1500' F.
S ace Vekcitya '1
:
1.02 1.01 1.01 1.06 0.91 1.07 1.00 1.08
95 80 72
.. 58
2a 100
100
100
..
99
100
100 90 87
..93 92
97
..
100
..
60 59
Per Cent of Theoretical Reaction ---C --ay-tsl 2b 3 4 5
2 100 100
86 87
..
.. .. 97 ..
100 91 72
100 90 90
.. ..
..
60
64
.. ..
77 82
----
6 100 100 100 100
..
96 95
7
85
..
58-
4i
..
44
Theor. vol. Hn/vol. oatralyst/hr. at rooin temp. and prassure.
only a few hours. Table VI show the effect, as measuredon75-co. samples, of 30-day exposures of catalysts to an atmosphere of steam and hydrogen on the activity subsequently measured at 1600' F. Catalysts No. 1 and 3 were exposed to hydrogen which had been saturated with water vapor at room temperature; the other materials were treated with a mixture of 1 volume of hydrogen and 2.5 volumes of steam. Although the catalysts were not noticeably affected by exposure a t 1800' F., all were very seriously damaged a t 1950' F. Significant amounts of carbon were not deposited on the inactivated catalysts during the brief activity tests a t 1600' F. No tests were made t o determine whether or not, amounts of carbon significant in commercial operations would deposit on these inactivated catalysts. The tests conducted in bench scale equipment employed small samples of material with a small gross particle size. The activities are therefore very much higher than those obtained in commercial reactors. Table VI1 and Figure 6 show the results of tests on plant sized extrusions (cylinders, X 7 / 1 ~ inch) of ratalyst 100
100
90
80
%
3
60
B
I
/
'i, lo
-
I-
0
E0
O
1
SUPPORTED CAT4LYSTS
- EXTRUDED
CATAIYSTS
P
2
40 I0,oo 0
Figure 3.
May 1952
d
so
2opoo SPACE
60
30,000
40POO
0
VELOCITY
Activity of Various Commercial Catalysts at
1500" C.
PER
Figure 4.
30
20
IO CENT
OF
40
NICKEL
Effect of Nickel Content on Catalyst Activity at 1500' C.
INDUSTRIAL AND ENGINEERING CHEMISTRY
1001
NICKEL-CATALYSTS
~~~
Effect of Nickel Content on Catalyst Activity at 1500" F.
Table IV.
Catalyst t y p e Nichel, yo
1 4 7
2 17 8
2 18 9
95 72 58 59
100 100 87 86 75 74
Pei Cent of Theoretical Reaction 100 100 100 100 100 100 100 100 100 100 100 99 ., 87 89 93 96 93 87 87 91 93 92 92 7-1 77 SO 88 76 83 75 77 76 79 78 84
Space Velocity
, .
.. Table V. Space Telocity
1
20 5
2 21 9
2 23 3
2 23.3
2 27 3
2 30 7
100 100
100 97 94 89
Effect of Temperature on Catalyst Activity Per Cent of _______
F.
13000
Theoretical Reaction 1500' F:
100 88
800
3,200 6,400 10,000 15,000 16,000 20,000 23,000 30,000
.. 45
2.5
37
80
..
29 , .
72
..
58
..
KO.2 in a eemi-pilot plant, reactor. This reactor had an inside diameter of 2.75 inches and a heated length of about 5 feet. The life of commercial catalysts is known to be 1 to 10 years in continuous industrial operation where methane is used as the process material. Until recently, when hydrogen was being produced from hydrocarbons higher in molecular weight than methane-for example, propane-or when t,heprocess &earn contained olefinic hydrocarbons, it r a s necessary to use a combination of catalysts t o avoid carbon format,ion. With the development of more active catalysts such as KO. 2, it' has been possible to produce hydrogen \%-ithoutany accompanying formation of carbon with only a single bed of catalyst, The life of these catalysts has been demonstrated comniercinlly to be 3 to 6 years depending on the temperature of operation and other operating variables. The physical strength of catalysts for the hydrocarbon-stealn reaction is of grcat importance when a life of several years is re-
quired. Spalling, dusting, and fusion must be minimized to avoid periodic shutdowns. Particle size and shape have considerable influence on the strength; a given cat'alyst extruded as rings is generally more fragile than in the form of pellets. Frequent shutdowns and start-ups reduce the lives of the catalysts, and various operational difficulties may inactivate any of them, either temporarily or permanently. Ehposure to gas streams cont'aining more than 0.001 mole % of hydrogen sulfide great'ly reduces catalyst activity and, in addition, may promote deposition of carbon on the catalysts. Conventional commelcial equipment readily reduces the sulfur content of normally gaseous hydrocarbons below this level. Activity may be restored, however, by exposure to a gas stream free of sulfur. The most conimon cause of permanent inactivation not associated with spalling is exposure to high temperatures. Carbon deposition on catalysts for the reaction of hydrocarbons with steam increases with t,he molecular weight' of the hydrocarbon and as the steam to hydrocarbon ratio is reduced. It has been proposed that, carbon be removed by intermittent steaming ( d ) , but this is unnecessary, a t least with hydrocarbons such as methane, ethane, propane, and butane, if a proper catalyst and operating conditions are employed. In the reaction of straightrun gasoline with steam a t 1700" F. over various catalysts similar t o No. 2 , it was observed in these laboratories that an increased nickel content reduced carbon depoeition. l l a n y metal oxides have been suggested as promotors for nickel catalysts for the reaction of hydrocarbons with st'eam (6, 11, 12). These materials, however, are claimed t o be particularly
Table VI.
Effect
of Exposure to High Temperatures on Catalyst Activity at 1600 O F.
500 Space Velocity AftP1...-.
suie
Exposure to 1800' 1950' F. F.
95 95 98 100 95 100
93 100 94 98 93 98
~~f~~~
Catalyst
expo-
38
61
60 43 63
1000 Space J'elocity 3000 Space Velocity .-.. After After __.."_ _^..". Before Exposure to
Before Exposure t o expo- 1800O 1930' sure F. I'. 94 90 80 90 85 90
98 94 82 98 82 87
exposure
1800' 19,50°
F.
28a 42 28 27 7 33
I'. 2 1" 21 3 4 0 13
Two-week exposure.
Table
VII. Semi-pilot Plant Determination of Cafalyst Activity 8 ace Vefocit y
Per Cent of Theoretical Reaction 14000 F. 1 M Q 0 F. 97.3 90.1 80.5
.. ..
20
0
ZG,OOG
10,OOO
SPACE
3(
8Q:9 84.1 83.3
)O SPACE
VELOCITY
Figure 5. XEffect of Temperature on Catalyst Activity
1002
98.3
Figure 6.
VELOCITY
Catalyst Activity in Semi-Pilot Plant Equipment
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 44, No. 5
N ICKEL-CATALYSTS effective a t temperatures below 1300" F., whereas tJhecommercial reactions are carried out at temperatures above 1300" F., usually 1500 F. I n view of the correlation between catalyst activity and nickel content (Figure 4), without regard to the other catalyst constituents. i t appears unlikely that the commercial catalysts studied in this laboratory are promoted. These catalysts are not selective, but act to bring about thermodynamic equilibrium with respect to all possible reactions of hydrocarbons and steam a t high temperatures (IO). It has been found necessary to maintain close control over the composition of the materials used in preparing the catalysts. Very small amounts of undesirable materials may be released from a catalyst t o be deposited at another point in the plant with serious results. For example, various metal oxides may be reduced at a high temperature and be carried as metal vapor to a lower temperature zone where the reaction may reverse and deposit a very voluminous powder of metal oxide. A few pounds of material deposited in this way are sufficient to plug a packed reaction vessel several feet in diameter. Both the life and activity of catalysts used for the reaction of hydrocarbons with steam in present plant practice are influenced t o a considerable degree by their nickel contents. The'other constituents of a catalyst and the method of preparation are probably chiefly important through effect on the porosity, surface area, and physical strengtp. Nickel shot and screens, for example, make relatively poor catalysts because of low porosity and low7 surface area. O
Catalysts that are inactive either because of low nickel content, . exposure t o a reducing atmosphere at very high temperatures, o r the presence of hydrogen sulfide are relatively selective for t h e decomposition of hydrocarbons to carbon and hydrogen. Highly active catalysts are better able to bring about reaction between hydrocarbons and steam without an accumulation of carbon, providing t h a t sufficient steam is present. LITERATURE CITED
Clark, E. L., Kallenberger, R. H., Browne, R. Y., and Phillips, J. R., Chem. Eng. Progress, 45, 651-4 (1949). Cope, W. C., Chem. Inds., 64, 920-5 (1949). Dieffenbach, O., and Moldenhauser, W., Ger. Patent 229,408 (1909).
Freyermuth, G. H., Small, J. K., and Hanks, W. V. (to Standard Oil Development Co.), U. S. Patent 1,904,441 (1933). I. G. Farbenindustrie, Brit. Patents 267,535 (1926); 323,855 (1928).
Mittasch, A., and Schneider, C. (to Badische Anilin and Soda Fabrik), U. S. Patent 1,128,804 (1915). Mond, L., and Langer, C., Brit. Patent 12,608 (1888). Murphree, E. U., Brown, C . I . , rrnd Gohr, E. J., IND.ENG. CHEM.,32,1203-12 (1940).
Reed, R. M., Trans. Am. Ins!. Chem. Engrs., 42,379-401 (1946). Reitmeier, R. E., Atwood, Kenton, Bennett, H. A , , Jr., and Baugh, H. M., IND.ENG.C H E X . 40,620-6 , (1948). Standard Oil Development Co., Ger. Patent 534,906 (1930). Williams, Roger (to E. I. du Pont de Nemours), U. 8.Patents 1,826,974, 1,830,010, 1,834,115 (1931); 2,119,565, 2,119,566 (1938). RECEIVED for review October 17, 1951.
ACCEPTEDJanuary 14, 1952.
RANEY NICKEL-CATA LYZED HYDROGENATION OF COMMERCIAL ALDOL C. KINNEY HANCOCK' Bureau o f Industrial Chemistry, The Utiiversity of Texas, Austin, l e x . T h e catalytic hydrogenation of aldol i s one step in one of the processes for synthesizing butadiene from natural gas. This reaction was studied in order to more nearly attain optimum conditions. The commercial aldol used appeared to be largely the condensation product between aldol and acetaldehyde. Under optimum hydrogenation conditions, the aldol yielded about 70% butylene glycol, alcohpl being the main by-product. A t higher temperatures, increased dehydration of aldol preceded hydrogenation and led to an increase in yield of butyl alcohol. The addition of water in amounts up to 30% does not greatly affect the yield of butylene glycol or the reaction time. Raney nickel can be re-used if it i s protected properly. Results obtained under various special conditions are reported. The results should be useful to those interested in the reduction of aldol and of related compounds.
catalytic dehydration of 1,3-butanediol t o yield, finally, 1 , 3 - b u t ~ diene. Some of the results of a study of the fourth reaction of this series are reported in the present paper, There has been considerable interest in the hydrogenation (or reduction) of aldol for a long time. This reaction, depending upon the conditions, may yield either butyl alcohol or 1,3butanediol. Butyl alcohol is the product if dehydration of aldol to yield crotonaldehyde precedes hydrogenation (or reduction); if preliminary dehydration of the aldol does not occur, 1,3-butanediol is the product. This paper is concerned primarily n i t h the latter reaction; however, the former reaction is of some concern since the extent of its occurrence materially affects the yielct of 1,3-butanediol. P R E V I O U S WORK
SERIES of studies related to the synthesis of 1,3-butadiene from natural gas was carried out in 1942 by technologists of the Bureau of Industrial Chemistry of The University of Texas. Research was concentrated on the following series of reactions for accomplishing the over-all synthesis: production of acetylene from natural gas by the Schoch electric discharge process ( I $ ) , catalytic hydration of acetylene, aldol condensation of acetaldehyde, catalytic hydrogenation of aldol, and 1 Present address, Department of Chemistry, The Agricultural and
A
hrechanical College of Texas, College Station, Tex.
May 1952
The literature on the hydrogenation (or reduction) of aIdol is abundant. Soon after t h e introduction of each new carbunyI hydrogenation catalyst or reducing agent, papers have been published on t h e application t o aldol. Among these are reduction by aluminum amalgam (6),electrolytic reduction ( I ) , yeast reduction ( I I ) , hydrogenation with platinum oxide catalyst ( 2 ) , hydrogenation with a supported copper catalyst ( 7 ) ,and hydrogenation with nickel catalyst a t 130Oto 150" C. (8) and a t 50' to 110" C. (9). During the past war, Chemische Werke Huls (IS) produced Buna-S-type synthetic rubbers with a rated capacity of 4000
INDUSTRIAL AND ENGINEERING CHEMISTRY
1003
