SEPTEMBER, 1935
INDUSTRI.2L AND ENGINEERING CHEMISTRY
the contact time which determines the composition of the reaction products. In the range of 1100' and 1400' C., temperature was without material influence on the yield of primary products. This \vas shown with the ethane and propane which yielded the same maximum percentages of ethylene a t both temperatures. Temperature had a greater influence on the yield of secondary products than of the primary. Ethane and propane produced small yields of acetylene a t 1100O C. In the case of propane a t 1400" C. the maximum acetylene yield was higher than that of ethylene. Ethane formed about seren times more acetylene at 1400" than at 1100' C. Aclcnowledgment The writers appreciate the assistance given by H. T. Bollman and C. I. Parrish in this work. Literature Cited (1) Berthelot, Compt. rend., 54, 517 (1862). (2) Egloff, Schaad, and Lowry, J . P h y s . Chem., 34, 1617 (1930).
(3) (4) (5) (6) (7)
(8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20)
1067
Fischer and Pichler, Brennsto,#-Chem., 13,406 (1932). Fischer, Pichler, Meyer, and Koch, Ibid., 9,309 (1928). Hurd and Spence, J . Am. Chem. SOC.,51,3356 (1929). Kassel, Ibid., 54, 3949 (1932) ; 55, 1351 (1933). Lebeau and Damiens, Ann. chim., 8,221 (1917). hlarek and McCluer, IKD. ENG.CHEM.,23,878 (1931). Marek and Neuhaus, Ibid., 25, 516 (1933). Neuhaus and Marek,Ibid., 24,400 (1932). Pease and Durgan, J . Am. Chem. Soc., 50,2715 (1928). Pring and Fairlie, J . Chem. SOC.,99, 1796 (191 1); 101, 91 (1912). Rudder, de, and Biedermann, Compt. rend., 190, 1194 (1930); Bull. SOC. chim., [4]47, 704 (1930). Schneider and Frolich, IND. ENG.C H m r . , 23, 1405 (.L931). Storch, IBD. ENG.CHEM.,26, 56 (1934). Storch, J . Am. Chem. SOC., 54,4188 (1932). Storch and Golden, Ibid., 54, 4662 (1932). Tropsch and von Philippovich, Brennstof-Chem., 4, 147 (1923). Wartenberg, von, Z. anorg. Chem., 52, 313 (1907). Wheeler and TVood, Fuel, 7, 535 (1928).
RECEIYED May 8, 1935.
Catalvtic Polvmerization of Gaseous Olefins by Liquid Phosphoric Acid I.
Propylene
V. N. IPATIEFF Universal Oil Products Company, Chicago, Ill.
HE polymerization reactions of the o l e h s have been less studied from a theoret,ical point of view than their other reactions, such as halogenation. During recent years interest in the gaseous olefins has grown apace because of the enormous quantities produced as a by-product of the cracking industry. Liquid phosphoric acid is an effective catalyst for the polymerization of propylene. .in explanation of its catalytic action is based on its ability to form esters with olefins. The ester molecules are assumed to react with each other to produce polymer and regenerate phosphoric acid or to liberate activated olefin molecules which react with molecules of ester or other molecules of olefin to produce polymers and regenerate phosphoric acid. Experiments have shown that olefins react with phosphoric acid a t relatively low temperatures (200' C. for ethylene, 125' C. for propylene) to form esters: /CH3
zation of many molecules of olefin since the acid is regenerated after each cycle. In one experiment on the polymerization of propylene, the quantity of polymer obtained corresponded to the polymerization of 110 molecules of propylene by a single molecule of phosphoric acid, and a t the end of the experiment the acid was as active as it was at the beginning. The following equation represents the decomposition of 2 molecules of isopropyl phosphoric acid with the regeneration of 2 molecules of phosphoric acid and the formation of hexylene: CHs CH,
' 4 I 0
I
OH O=P/ \OH
CHj CH3
+
aH/ ' I
0
O=P/
OH \OH
CHI CH,
Y
+
AH
A
$-
2PO(OH)a
CHI CHI
The esters may eliminate the elements of phosphoric acid in different ways, thus giving rise to isomeric polymers. The CH?=CH--CH3 ci O=P - OH first formed, hexylene, may react with phosphoric acid to form hexyl phosphoric acid which in turn may react with O 'H O 'H propyl phosphoric acid to pro.. . These esters have been isolated duce n o n y l e n e . In the same and subsequently c o n v e r t e d way n o n y l p h o s p h o r i c acid Propylene polymerizes in the presence of into polymer and p h o s p h o r i c may react with p r o p y l p h o s liquid phosphoric acid to a mixture of acid; that is, the polymerizap h o r i c acid to form dodecylmonoolefins. Propylene polymerizes more tion process has actually been ene, or 2 molecules of h e x y l readily in the presence of the more reactive c a r r i e d o u t i n t w o steps as phosphoric acid may produce postulated by the hypothesis. dodecylene. butylenes than when alone. A mechanism At the t e m p e r a t u r e s emUnder m o d e r a t e polymerizhas been suggested for the polymerization p 1o y e d in polymerization, the ing conditions, 135' to 200" C. of olefins in the presence of phosphoric acid life of these esters is probably a t 1 to 15 atmospheres preswhich involves the formation of intermevery short. A single molecule of sure, propylene polymerizes to a diate esters. phosphoric acid should be able liquid consisting almost entirely to bring about t h e p o l y m e r i of monoolefins, p r e s u m a b l y /OH O=P - OH
+
/OCH\CH3
INDUSTRIAL AND ENGINEERING CHEMISTRY
1068
TABLE I. PROPERTIES OF PROPYLENE POLYMER Fraction
No.
Formula
B. P.
c.
Gas 1 2 3
4 5
6 7 8 9 10 11 Loss
Volume
n'D"
0:680 0.708
1.3930 1.4093 1.4159 1.4222 1.4247 1.4278 1.4350 1,4380 1.4443 1.4549 1.4960
% ..
-25 25-73 73-110 110-127 127-130 130-136 136-140 140-169 169-181 181-200 200-220 Above 220
... . .
di0
1.9 6,3 6.9 2.0 12.4 27.1 4.7 5.2 3.7 8.1 7.2 2.1 2.4
0:739 0.741 0.746 0.760 0.770 0.782 0.806
...
.. .
....
Bromine No. of Found Calcd. Polymer
158
190
COHI~
136
127
CeHis
91
92
2.8 per cent n-butane, and 31.6 per cent noncondensables a t -160" C. Table I1 presents analytical and refraction data on certain fractions of the propylene polymer which had been doubledistilled through a Podbielniak column. The low bromine number and incomplete solubility in 96 per cent sulfuric acid a t 0" C. of fraction 1, Table I, indicated the presence of saturated hydrocarbons in the hexylene fraction as did also the carbon-hydrogen ratio.
C~~HM
....
of isostructure. The liquid polymer distills from 40" t o 230" C. with very little bottoms. The evidence for the chemical nature of this polymer product is fourfold. Propylene polymer is practically 100 per cent soluble in 96 per cent sulfuric acid a t 0" C.; catalytic hydrogenation of the polymer a t 220" C. and initial hydrogen pressure of 96 atmospheres produces only paraffinic hydrocarbons, which indicates the absence of naphthenes and aromatics; the bromine number of the polymer agrees with that calculated for monoolefins; the carbon-hydrogen ratio corresponds to CnHSn. Under more severe polymerizing conditions (higher pressures and temperatures and longer contact times), the reaction of polymerization is followed by other reactions and the liquid product contains not only olefins, but also naphthenes, aromatics, and paraffins. This phase will be discussed in a forthcoming paper. Propylene is polymerized more rapidly by acid previously used for polymerizing butylenes than by fresh acid. In the polymerization of mixtures of propylene and butylene, there are obtained not only the polymers of each of these hydrocarbons, but also mixed polymers due to combination of the two olefins: C~HTOPO(OH)Z CaHsOPO(OH)2 + C ~ H M ZPO(0H)s
+
VOL. 27, NO. 9
+
The evidence for this conclusion is Podbielniak distillation data of the liquid polymer obtained from individual olefins and from mixtures. Polymerization of Propylene at Superatmospheric Pressure with Liquid Phosphoric Acid
Propylene was bubbled through 166 grams of 100 per cent orthophosphoric acid a t 51 atmospheres gage pressure and 204" C. The propylene was passed through the acid a t such a rate (exit rate, 8.5 liters per hour) that about 50 per cent of the gas was polymerized. The liquid polymer was removed continuously. During 312 hours of operation a total of 5960 cc. of liquid polymer was obtained which corresponded to a 55 per cent weight conversion of the propylene passed. Distillation data are presented in Figure 1, and the properties of the various cuts are listed in Tables I and 11. The composition of the dissolved gas fraction was 61 per cent propylene, 2.0 per cent propane, 2.6 per cent isobutane,
FIGURE1. PODBIELNIAK DISTILLATION OF PROPYLENE POLYMER
Table 111presents characteristics of the fractions obtained by redistillation (Podbielniak) of fraction 1, Table I (boiling point 25" to 73" C.). TABLE 111. PROPERTIES OF LOW-BOILING PROPYLENE POLYMER Fraction No. Gas 1 2 3 4 5
-Bromine B. p.
c.
-36 36-59 59-60.5} 60.5-63 63-64.5 Above 64.5
Volume
dqa
% 1.9 96.s
1.3
ng ....
Found
...
0:667 (0.667 0.681
1.3860 1.3930 1.3962
151 182 170
0.683
1.3987 1.4150
182
...
No.-
Calcd. for CeHn
190
. ..
All the remaining fractions (2 to 11, inclusive, Table I) decolorized permanganate solution instantly, reacted with nitrating mixture (3 volumes of 1.840 sulfuric acid plus 1 volume of 1.495 nitric acid), and dissolved completely in 9G per cent sulfuric acid a t 0" C. The polymer boiling a t 127" to 140' C. (fractions 4, 5, and 6, Table I) represented 44.2 per cent of the total liquid yield and consisted apparently of isomeric nonylenes, whereas fractions 7, 8, and 9 (Table I) consisted largely of isomeric dodecylenes. Hydrogenation of Nonylene Fraction
The polymer distilling a t 130" to 140" C. (analysis: carbon, 85.5; hydrogen, 14.5) was hydrogenated a t 240" C. and under an initial hydrogen pressure of 100 OF PROPYLENE POLYMER TABLE11. PROPERTIES atmospheres in a rotating autoclave in the presMol. Refraction Frac--Analyses, Per Centence of a catalyst consisting of two parts of nickel tion For- -Calcd.Mol, N ~ ,B. p. mula c H -Found-c H Wt,= ny diO Calcd. Founds oxide and one part of iron oxide. The hydrogenated product distilled a t 140" to 145" C. It c. 1 90-100 85.0 15.0 1.4055 0.706 2 130-137 CeHn 85.7 14.3 85.4 14.4 134 1.4215 0,735 45:9 46:3 did not permanganate Or 3 132-137 85.6 14.3 , . , , . .. ... .. .. react with nitrating mixture. Distillation and 4 149-151 85.3 14.4 ... 5 186-196 cI2H2, 85.7 14.3 8 5 . 5 14.3 181 1:iiig o:,+jg 6i:4 6i:8 analytical data indicated that it was a mixture 6 210-250 ClaHaa 85.7 14.3 85.6 14.2 210 1.4465 0.789 71.0 71.1 of isomeric nonanes. a Molecular weights,were determined b y the freezing point meth,od in benzene. b Calculated accordlng to the Lorentz-Lorenz formula aesumlng one double bond per ANALYSIS. Calculated for CpHm: carbon, 84.1; hy0
molecule.
drogen, 15.6. Found: carbon, 84.4; hydrogen, 15.6.
INDUSTRIAL -4SD ENGINEERING CHEMISTRY
SEPTEhTBER, 1933
Isolation of Intermediate Ester
Propylene was contacted in a rotating autoclave with 90 per cent orthophosphoric acid at 125" C. and initial pressure of 10 atmospheres. The reaction product was a homogeneous liquid which presumably contained isopropyl phosphate. When this liquid was heated a t 150" C. in the same apparatus, two layers were formed. The upper layer consisted of propylene polymer, and the lower layer was phosphoric acid which was capable of polymerizing additional propylene. A similar experiment was made with ethylene, which was heated with 90 per cent acid a t 200" C. under an initial pressure of GO atmospheres. The reaction product was a homogeneous liquid. A sample of this liquid was neutralized by barium hydroxide solution, and the resulting barium salt was analyzed for barium ((weighedas barium sulfate) and for phosphorus (weighed as magnesium pyrophosphate). The analytical figures agreed fairly well with those for the barium salt of monoethyl phosphoric acid. Alrau~srs. Calculated for C2HrBaPOa: barium, 52.5; phosphorus, 11.9. Found: barium, 53.3; phosphorus, 12.1.
T h e n the ester was heated in the same apparatus a t 330" C., two layers were formed, an upper polymer layer and a lower phosphoric acid layer. Accelerating Effect of n-Butylenes upon Polymerization of Propylene
Pure propylene was polymerized by 100 per cent phosphoric acid a t 135" C. and atmospheric pressure, but its rate of polymerization was accelerated by the presence of butylenes or by merely passing them through the acid for a short time. For example, propylene was polymerized to the extent of 13 per cent over a period of 3 hours by a sample of fresh acid. At the end of this time the propylene was replaced by abutylene which was passed through the acid for 1 hour. Finally, propylene was again passed through the acid under
1069
10 atmospheres gage pressure. These were conditions under which propylene is able to polymerize alone, without the activating effect of the butylenes. Distillation data of the liquid polymer are presented in Figure 2. In spite of the fact that the gas mixture contained a high percentage of propylene, the product contained only a small amount of nonylene (i. e., fraction boiling a t 130" to 140" C.) which was the chief product when propylene was polymerized by itself. About 50 per cent of the polymer boiled a t 80" to 110" C., apparently consisting of seven- and eight-carbon olefins.
Acknowledgment
The author is indebted to B. B. Corson, A. Yon Grosse, V. Komarewsky, H. Pines, and R. E. Schaad for the experimental work, and to I. D. Kurbatov and R. C. Wackher for the analytical data.
11. Butylenes V. N. IPATIEFF
AND
B. B. CORSOK
The isomeric butylenes are polymerized by orthophosphoric acid at atmospheric pressure and relatively low temperatures to liquid polymers. These polymers are monoolefins. Isobutylene polymerizes the most readily, and a-butylene the least. The presence of isobutylene accelerates the polymerization of the n-butylenes.
B
UTYLENES are polymerized by phosphoric acid and the mechanism is assumed to be the same as that of propylene, as described in Part I. The speed of polymerization of the butylenes is greater than that of propylene, the rates increasing in the following order: propylene, a-butylene, @-butylene, isobutylene. The liquid polymerization products of the isomeric butylenes are similar in physical and chemical properties. They are mixtures of liquid monoolefins. The evidence for their chemical nature is the same as that for the propylene polymers-namely, they are practically 100 per cent soluble in 96 per cent sulfuric acid a t 0" C., they are converted into paraf, I I fins by catalytic hydrogenation, their bromine numbers od 10 NJ 30 A /L2= agree with that calculated for monoolefins, and their carbonFIGIJRE2. PODBIELNIAK DISTILLATION OF PROPYLENE- hydrogen ratios correspond to that of C,H*,. BUTYLENE POLYMER Gentle polymerizing conditions favor the production of simple polymer mixtures, whereas more drastic conditions the same operating conditions as those used in the first proyield more complicated mixtures. For example, the isopylene period. The propylene was absorbed to the extent of butylene polymer produced a t 30" C. contained only two 39 per cent over a period of 6 hours after this activation. ISO- compounds, whereas polymer made a t 130" C. contained and P-but#yleneswere found to produce the same effect as aseven compounds. butylene. The presence of isobutylene accelerates the polymerization of the n-butylenes. A mixture of iso- and n-butylenes polyMixed Polymer Obtained by Polymerization of merizes a t lower temperature and with lower acid concenOlefin Mixture tration than the n-butylenes alone. Not only does propylene polymerize more readily in the Preparation of Butylenes presence of butylene, but also the liquid polymer produced from a mixture of propylene and butylene is different than The butylenes were prepared in a semi-automatic glass that obtained from propylene or biutplene individually. A apparatus (1) by catalytic dehydration (8) of the correspondmixture of propylene and butylenes (20 per cent of propylene, ing alcohols over activated alumina a t 375" to 425" C. The 10 per cent of n-butylenes, 5 per cent of isobutylene, 65 per a-butylene (prepared from n-butyl alcohol) and the isobutylcent of propane and butanes) was polymerized at 200" C. and ene (prepared from tertiary or isobutyl alcohol) mere pure,
LA-
