M A R C H , 1940
INDUSTRIAL AND ENGINEERING CHEMISTRY
Literature Cited (1) Abraham, Herbert, “Asphalt and Allied Substances”, 4th ed., p. 1011, New York, D. Van Nostrand Co., 1930. (2) Arnold, H., 2. angew. Chem., 36,545(1923). (3) Bohn, R., U.8.Patent 898,307(1908). (4) Chemische Fabriken K. Albert, German Patent 387,836(1918); J. SOC.Chem. Ind., 43,797B (1924). (5) Ellis, C., American Perfumer, 18, 541 (1923). (6) Ellis, C., U.S. Patent 1,948,442(1934). (7) Ibid., 1,976,774(1934). (8)Ibid., 2,042,299(1936). (9) Folchi, P., Chem.-Ztg., 46, 714 (1922); J . SOC.Chem. Ind., 41, 720A (1922). 110) Frolich, P. K.,U. S. Patent 2,031,944(1936). 111) Fulton, S.C., Ibid.. 1,981,824(1934). 32) Ibid., 2,035,123(1936). :13)Ibid., 2,055,486(1936). 114) Fulton, S. C.,and Kalichevsky, V., Ibid., 2,006,199(1935). :15)Fulton, S.C., and Kunc, J., Ibid., 2,025,738(1935).
309
(16) Ibid., 2,038,558(1936). (17) Gardner, H.A., “Physical and Chemical Examination of Paints, Varnishes, Lacquers and Colors”, 8th ed., p. 193 (1937). (18) Gukhman et al., Azerbaldzhanskoe Nejtyanoe Khoz., No. 5, 72 (1925). (19) Marcusson, J., Chem.-Ztg., 37,882 (1914); J. SOC.Chem. Ind., 38, 98A (1919); 2. angew. Chem., 29, 346 (1916),31, 113 (1918);Petroleum Z., 12,1149 (1917). (20) Meister, Lucius, and Bruning, German Patents 403,264,406,152, 406,999(1919); J . SOC.Chem. Ind., 44,461B (1925). (21) Nastyukov, A. M., J. Russ. Phys. Chem. Soc., 36, 881 (1904); J . SOC.Chem. Ind., 86 (l),801 (1904);British Patent 289,920 (1927). (22) Ormandy, W. R.,and Craven, E. C., J . Inst. Petroleum Tech., 10, 99 (1924). (23) Richardson, C., J. IND. ENQ.CHEM.,8, 319 (1916). (24) Sachanen and Vasil’ev, Nejtyanoe Khoz., 13,334(1927). (25) Severin, E., Mon. petrole rounuzin, 21,22 (1911). (26) Tvertzuin, Neftyanoe Khoz., 11, 732 (1926). (27) Wise, C.R.,and Edwards, D. F., U.5. Patent 2,018,771(1935).
CATALYTIC DEHYDROGENATION OF MONOOLEFINS TO DIOLEFINS Source Materials for Synthetic Rubber and Resins ARISTID V. GROSSE, JACQUE C. MORRELL, AND JULIAN M. MAVITY Monoolefins have been dehydrogenated catalytically to give conjugated diolefins of the same carbon framework. The diolefins formed were 1,3-butadiene from nbutenes, isoprene from the branched-chain pentenes, and piperylene from 2-pentene. The once-through yields varied from 11 to 30 per cent, and ultimate yields of 1,3butadiene up to 79 per cent resulted. Cyclopentadiene was obtained by dehydrogenating cyclopentane. SIDE from the scientific value of the method described
A
here for the catalytic dehydrogenation of monoolefins to diolefins, the present contribution has an important industrial, commercial, and military value-viz., as an economic source of raw material for synthetic rubber. The production of butenes from butanes and pentenes from pentanes has already been described (3, 9). The present paper, showing the production of butadiene from butenes and isoprene from pentenes, is the connecting link between the billions of cubic feet of butanes present in natural and cracked gases and of butenes present in the latter, and the billions of gallons of pentanes available in natural gasoline and crude oil on the one hand, and the production of synthetic rubber from these raw materials on the other. The basic raw materials for the production of synthetic rubber therefore now include our tremendous resources of hydrocarbon oils, hydrocarbon gases, and coal to produce
Universal Oil Products Company, Chicago, Ill.
synthetic hydrocarbons if and when our petroleum resources become exhausted. The production of synthetic rubber from butadiene and isoprene is well known. Wallach ( l a ) exposed isoprene to light and produced synthetic rubber. Matthews (8) and Harries (6) independently used metallic sodium to polymerize isoprene to rubber. Similar work has also been done by others. So-called Buna rubbers (7), made and used on a commercial scale in Germany, are polymers or mixed polymers of butadiene synthesized from acetylene: Acetylene + acetaldehyde butene glycol + butadiene
+ acetaldol + + rubber polymers
Most of the synthetic Buna rubber is not polymerized by sodium but is produced by emulsion polymerization. Also the commercial Buna rubbers are copolymers of butadiene with other materials. Similar developments have taken place in Russia ( 1 ) where ethyl alcohol is employed as a source of butadiene. However, as one of the authors pointed out (Q), “the development of the synthetic rubber industry depends upon the production of cheap butadiene and isoprene”, and “catalytic dehydrogenation of butenes or pentenes or corresponding saturated hydrocarbons, butanes, and pentanes, points the way to cheap production of butadiene and isoprene”. Another important development is the production of synthetic resins of the resin-rubber or rubber-resin type by the copolymerization of butadiene with another olefin, e. g., styrene, the properties of the product depending upon the relative proportions of the diolefin and monoolefin. I n the previous papers (3,9) the catalytic dehydrogenation of gaseous paraffins to monoolefins was described. This process is not limited to the production of olefins from paraffins;
INDUSTRIAL AND ENGINEERING CHEMISTRY
310
the olefins can be further dehydrogenated with the same catalysts [chromium, molybdenum, or vanadium oxide on alumina (8, 4, 9)]to diolefins. The diolefins formed are of the conjugated type and have the same carbon framework as the parent olefin.
VOL. 32, NO. 3
to the behavior of 1,3-butadiene in the presence of the dehydrogenation catalysts. I n this latter case the formation of liquid polymerization or condensation products (about 5 per cent) was observed. Single-pass yields of diolefins from monoolefins up to 20-30 per cent were obtained. I n the vacuum dehydrogenation of butenes. recvcle vields on the order of 60 to 79 per cent are possible. I
FIG. I
v
AUTOMATIC VACUUM
"
"
Conditions
CONTROL APPARATUS
The reaction with which we are chiefly concerned may be represented by the general equation: CsGCH-CHe -C=C-C=C+Hp Alefih I I b l I 1,3- iolefin
T O SWITCH AND RELAY
'
[This equilibrium for butene-butadiene was recently investigated by Dement'eva, Frost, 0 RELAY AND VARIAC and Serebryakova (2) in the range 480-534' C.] The olefin in the presence of hydrogen is also BRASS NEEOLE I N CLASS ~ U B E in equilibrium with the corresponding paraffin, but this reaction is negligible under the conditions of the present experiments. As is the case with the dehydrogenation of paraffins, the equilibrium Thus from 1- or 2-butene, 1,3-butadiene is formed; from straight-chain pentenes, piperylene (1,3-pentadiene) ; and of this reaction is shifted to the right with increase in temperafrom branched-chain pentenes, isoprene (2-methyl-1,3ture. Moreover, since the reaction to the right represents an increase in the number of moles, it is favored by decrease in butadiene). The original position of the double bond in the pressure. I n view of these considerations the reactions were framework of the olefin is probably of no consequence since, especially in the presence of the alumina base catalyst, it is performed a t reduced pressure-viz., 0.25 atmosphere and lower and in most cases a t a temperature of 600-650" C. freely shifted (6, IO). Thus isoprene was obtained in approximately equal yields from either 3-methyl-1-butene or from a Experimental Procedure mixture of 2-methyl-1-butede and 2-methyl-2-butene. The dehydrogenations were carried out by passing the charge at a definite rate through a section of granular catalyst in a quartz tube. The catalyst zone was heated in the constantTABLEI. IDENTIFICATIOR' O F CONJUGATED DIOLEFIR'S tem erature zone of an electrically heated aluminum-bronze .M. P. of bloci furnace. Condensable products were collected in solid Derivative, carbon dioxide traps, and the noncondensable gases were pumped Diolefin Derivatives Prepared c. from the system by means of a Nelson vacuum pump which permitted metering and sampling for analysis. 1,a-Butadiene 1,2,3,4-Tetrabromobutane The pressure was automatically controlled by a solenoid valve High-melting form 116 arrangement, the essentials of which are shonrn in Figure 1. The Low-melting form 38.5-39 valve consists of a brass stem ground into a glass seat. An iron 1,4-Dibromo-2-butene 52 core is attached at the top of the brass stem. This is actuated cis - 5 - Methyl - A4 - tetrahydroIsoprene phthalic anhydridea 62.5-63. ba O
-
-
cis - 6 Methyl A4 - tetrahydrophthalic anhydride Piperylene 1,2,3,4-Tetrabromopentane Cyclopentadiene Maleic anhydride addition product (probably cis-endomethylene-3,6tetrahydrophthalic anhydride)
Piperylene
60-61 112-113 162
Neutralization equivalent (by hydrolysis with excess alkali and back titration) : calcd. for cis-5-methyl-A4-tetrahydrophthalicanhydride, 83; found, 81. Mixed melting point with an authentic sample showed no depression.
*
One conjugated diolefin (1,3-cyclopentadiene) was obtained in one operation from the corresponding saturated hydrocarbon cyclopentane. The single-pass formation of diolefins from saturated hydrocarbons is not limited to the cyclopentane ring system. I n the dehydrogenation of n-butane to butenes, small percentages of lJ3-butadiene are produced, the amount depending on the conditions. Olefins whose carbon frameworks do not permit the introduction of conjugated double bonds-. g., ethylene and propylene-gave as the predominating reaction hydrogen and carbon. No tendency to form acetylenes or diolefins of the allene type was observed. These observations also apply
1
1
1
1
1
I
1
MARCH, 1940
INDUSTRIAL AND ENGINEERING CHEMISTRY
311
ultimate yields are obtained by recycling a t low CONJUGATED DIOLEFINS B Y DEHYDROGENATION" contact times, where the extent of side reactions Unis small. Compounds Contact --Diolefin-reacted Carbon formation in the dehydrogenation of Dehydrogenated Temp. Time Name Yield Charge Carbon Wt. % of Wt. % of olefins is considerably higher than in the dehydro'C. Sec. charoe Wt. % charge genation of paraffins and represents over 10 per n-Butenesb 600 0.75 1,a-Butadiene 18 50 11.2 n-Butenesb 600 0.34 1,3-Butadiene 20.6 59 4.8 cent of the charge in some cases (Table 11). This 3-Methyl-1-butene 600 0.5 Isoprene 21.4 34C 12.8 is favored by keeping the reaction products too 2-Methyl-1-butene + 2-methyl-2-butened 600 600 0.3!3 Isoprene 22.3 44 6.2 long in contact with the catalyst and, conversely, 2-Pentene 0.40 Piperylene 30.3 44 7.6 Cyclopentane 500 1.85 Cyclopentadiene 8.98 62 8.8 can be minimized by operating at short contact Catalyst, 4% chromium oxide,on alumina. pressure, 0.25 atmosphere (190 m m . ) times (Table 111). The carbon-forming characb Mixture prepared b y dehydration of n- anh see-butyl alcohols over alumina at 400° C . teristics of the diolefins are illustrated by a n exAnalysis b y Podbielniak fractionation method indicated: 1-butene 51.6%, 2-butene 43.3 propane 1.7. residue above butenes 3.4; total olefins b y bromine water absorption 94.5%; periment in which butadiene itself was passed hlost of the Cs olefins recovered were the higher boiling branched-chain isomers of 3methyl-1-butene. These are included in t h e 3470. over the catalyst: 1,3-Butadiene was subjected d From dehydration of terl-amyl alcohol over alumina a t 400' C. with 3-methyl-1-butene to the dehydrogenation catalyst at 600" C., removed. This mixture boiled a t 27.2-37.6O (733 mm.), ng 1.3915. T h e formation of a small amount (2.7%) of cyclopentene is indicated by indirect meth0.24 atmosphere, and a contact time of 0.34 ods. second. The products recovered included carbon 16 Der cent. liauid moducts 6. butane 1. butenes 20, 'and unreactkd 1,kbutadiene40. The liquid, a by means of the solenoid when the circuit is completed in the result of polymerization and condensation reactions, probably proper arm of the mercury manometer (so constructed that either contributes t o carbon formation. It boiled over a wide range side may be used). One side of this manometer is left open to and contained, among other products: benzene, about 0.5 the system, the other being closed when the desired pressure is weight per cent of the 1,3-butadiene charged; styrene, about reached. The variety of adjustments of which the apparatus is capable makes it applicable to a wide range of pressures and 1.0 weight per cent; and a high-boiling hydrocarbon (above space velocities. For example, the position of the solenoid can be 190') with a n intense blue color similar to that of azulene. adjusted so that the valve is opened when the circuit is completed (This blue color was also observed in the high-boiling liquid (position A ) ; or it can be adjusted so that the valve is held shut when the circuit is complete (position B ) . If desired, a portion fraction from the dehydrogenation of 2-pentene.) Similar of the gas may be by-passed by adjusting the microscrew clamp. results were obtained with 1,3-butadiene a t 450" C., 0.25 The condensed reaction products were usually fractionated atmosphere and 3.6 seconds contact time. The products in a Podbielniak column and the cuts investigated by chemical included carbon 12.1 per cent, liquid 5, butenes 34, butane methods. CATALYSTS.In general the catalysts were of the chromium, 2, and 1,3-butadiene 38. The butenes and butane arise from molybdenum, or vanadium oxide on alumina type, recently dehydrogenation of the charge with hydrogen formed by described (3, 4,9). The preparation of a laboratory chromium composition of a portion of the charge. oxide on alumina catalyst was also given in detail (4). The results described in the present paper were obtained with alumina im regnated with 4 per cent by weight of chromic oxide. T.4BLE 111. DE€lYDROGENATlONO F TZ-BUTENES~ OF PRODUCTS. The diolefins Rere identified by the preparation of crystalline derivatives, either the maleic Contact Yield of 1,3-Butadiene Temp. Pressure Time Single-pass Recycle Carbon anhydride addition compounds, the tetrabromides, or both (Table I). Butadiene was determined in vaporized samples by See. OC. Mm. Vol. V0 absorption in maleic anhydride (11). This method was also 600 190 0.75 18.7 37 11.2 adapted to the &carbon diolefins by vaporizing a weighed sample 600 190 0.7 22 42 in sufficient nitrogen to keep it in the vapor phase. 600 190 0.4 22.9 .. 5: 1 TABLE 11.
FORMATION O F
5
C
8
PDENTIFICATION
Results The yields of the diolefins under the conditions used are given in Table 11. They do not necessarily represent the optimum conditions. T o obtain the optimum, a series of experiments under different conditions was made with nbutenes to demonstrate the effect of temperature, pressure, and contact time on the yield of butadiene. The yields (once-through) plotted as a function of contact time are shown in Figure 2. Contact times were calculated from the equation:
c' T* = 743(273 + 2') where C. T.
=
Put [g/M
+ S(g'/M')]
contact time
p = mean pressure (mm. Hg)
v = volume of catalyst zone, cc. t = duration of run, minutes T = av. catalyst temperature, O C. g = grams of change M = molecular weight of charge g' = grams of each recovered product M' = molecular weight of each recovered product
The free space of the catalyst zone (70 per cent) is taken into account in the constant of the denominator. These data are also given in Table I11 which includes calculated recycle yields (based on analytical data). The dehydrogenation is accelerated at the same contact time by either a n increase in temperature or a decrease in pressure. The best
600 168 0.34 21.4 52 4.8 6006 197 0.12 13.5 54 1.5 600 19s 0.045 11.2 62 0.8 650 192 0.068 21.8 53 2.3 650 192 0.055 19.3 56 2.1 650 189 0.041 16.6 60 1.4 650 180 0.028 13.3 69 0.9 650 168 0.018 11.9 79 n A 650 63 0.026 21.8 51 0.9 650 63 0.019 18 60 0.8 650 63 0.013 17.0 65 0.5 650 80 0.012 14.7 69 0.4 a F o r source and composition of butene used in t h e first four experiment. see Table 11, noteb. T h e butenes used in t h e subsequent experiment; were prepared from pure sec-butyl alcohol and analyzed 99.0% n-hutenea. b Average of three experiments. ~~
~
Acknowledgment The authors express their thanks to E. E. Zetterholm for his assistance in part of the experimental work.
Literature Cited (1) Akobzhanov, Rubber Chem. Tech., 8, 430 (1935). (2) Dement'eva. Frost, and Serebryakova, Compt. rend. acad. sei. U.R. S.S.,15, 141 (1937). (3) Grosse and Ipatieff, IND.ENG.CHEM.,32,268 (1940). (4) Grosse, Morrell, and Mattox, Ibid., 32, to be published (1940). (5) Harries, Ann., 383, 157-227 (1911). (6) Ipatieff, Ber., 36,2004 (1903). (7) Koch, Rubber Chem. Tech., 10, 17 (1937). (8) Matthews and Strange, British Patent 24,790(1910). (9) Morrell, OQ Gas J . , 37,42,55 (1939). (10) Norris and Reuter, J . Am. Chem. SOC.,49,2624 (1927). (11) Tropsch and Mattox, IND. ENQ.CHEM., Anal. Ed., 6, 104 (1934). (12) Wallach, Ann., 238,88 (1887).
