AUGUST, 1935
INDUSTRIAL .4ND ENGINEERING CHEMISTRY
erization. Since iqonierization reactions have low energie. of activation, condition- favorable for isomerization are low temperatures and long contact times.
Literature Cited Berthelot, Ann. chim. p h y s . , [4] 9, 402 (1866), 12, 52 (1867); Bull. soc. chim., [ 2 ] 6, 268 (1866); Compt. rend., 62, YO5 (1866), 63, 479, 515 (1866); J . pharm., [4] 3, 350 (1866); 2 . Cherri., 9, 337 (1866). Bone and Coward, J . Chem. Soc., 93, 1212 (1908). Borissaw. Schachuazarowa. and Rlargolis, private communication. ESG. CHEM., 10,901 (1918). Davidson, J. IXD. Dunstan, Hague, and Theeler, J. Soc. C h e m . I n d . , 50, 313T (1932); IKD. ENG.CHEU.,26, 307 (1934). Dunstan, Hague, and Wheeler, prk-ate communication. Ebrey and Engelder, IND.ESG. CHEM.,23, 1033 (1931). Engler and Rogowski, in Engler's "h-eueren Ansichten iiber die Entstehung des Erdols," p. 24 (1909) ; Roulata, Dissertation, Karlsruhe, p. 49 (1909). Fischer and Pichler, Brewnstof-Cheni., 13, 381 (1932). Fischer and Pichler, Ibid., 13, 406 (1932); Chem.-Ztg., 57, 504 (1933). Fischer, Pichler, Meyer, and Koch, Brennstof-Chem., 9, 309 (192R\. \ - - - -
Frey and Hepp, IXD. ENC.(:HEM., 25,441 (1933). Frey and Smith,Ibid.,20, 948 (1928). Hague and Wheeler, J . Chem. Soc., 1909,391. (14.1) I b i d . , 1929,378; Fuel, 8,560 (1929). ESG.CHEM.,26, 50 (1934). (15) Hurd, IND. (16) Hurd and Meinert, J. Am. Chem. Soc., 52,4978 (1930). (16A) I b i d . , 53, 289 (1931). ( l i ) Hurd and Spence, J.Am. Chem. Soc., 51,3353 (19299). (18) Ibid., 51, 3561 (1929). (19) Ipatieff and Huhn, Ber., 36,2014 (1903). (20) Kassel, J . Am. Chem. Soc., 53, 2143 (1931). (21) Ibid., 54, 3949 (1932). (21A) Ibid., 56, 833 (1935). (22) Krause, Nemcov, and Soskira, Compt. rend. acad. sci. C . R . S.S., 11, No. 5,301 (1934). (23) Lang, Thesis, Columbia University, 1934.
933
(23A) Lebedev and Kobliansky, J. Gen. Chem. ( U . S . S. R.), 4, 13 (1934). (24) Mailhe, Chimie et industrie, 29,759 (1933). (25) Mailhe, Cmnpt. rend., 194, 1947 (1932). (26) Marekand Neuhaus, ISD.END.CHmr., 25,516 (1933). 52,4540 (1930). (27) Meinert and Hurd, J . Am. Chem. SOC., (28) Meyer and Fricker, Ber., 47,2765 (1914). (29) Meyerand Tanren, Ibid., 46, 3183 (1914). (30) Mignonac and Dietr, Compt. rend., 199, 367 (1934). (31) hlignonac and Saint Aunay, de, Ibid., 189, 106 (1929). (3lA) Nef, Ann., 318,24,25,219 (1901). (32) Neuhaus and Marek, IXD. ENG.CHEhr.,24, 400 (1932), (33) Paneth, T r a n s . Faraday Soc., 30, 186 (1934). (34) Pease, J . Am. Chem. Soc., 50,1779,2715 (1928). (35) I b i d . , 51, 3470 (1929). (36) Ibid., 53, 613 (1931). (37) Ibid., 55, 3198 (1933). (38) Rice and Dooley, J . Am. Chem. Soc., 56, 2747 (193411. (39) Rice and Glasebrook, Ibid., 56, 2381, 2472 (1934). (40) Rice and Rice, "Aliphatic Free Radicals," Baltimore. John3 Hopkins Univ. Press, 1935. (41) Rudder, de, and Biedermann, BUZZ.Soc. Chim., [4] 47,704 (1930 I : C m p t . rend., 190,1194 (1930). (41A) Saint Xunay, de, Chimie et industrie, 29, 1011 (1933). (42) Schneider and Frolich, IND. ENG.CHEM.,23, 1405 (1928). (42A) Sherman and Eyring, J . Am. Ciiem. Soc., 54, 2661 (1932). (43) Storch, IND.ENG.CHEW,26, 56 (1934). (44) Storch, J . Am. Chem. SOC., 54,4188 (1932). (45) Ibid., 56, 374 (1934). (46) Taylor and Jones, J . Am. Chem. SOC.,52,1112 (1930). (47) Taylor and van Hook, private communication. ESG. CHEM.,to be published. (47-1) Tropsch and Egloff, IND. (48) Vaughan, J . -4m. Chem. Soc., 55,4115 (1933). (49) Wheeler and Wood, Fuel, 7,535 (1928). (50) Wheeler and Wood, J. Chem. S O C . 1930,1819. , (51) Wheeler and Wood, Nature, 122, 773 (1928). (52) Whitby and Kata, IND. EXG.CHEM.,25, 1338 (19331. (53) Williams-Gardner, Fuel, 4,430 (1925). (54) Wood, see Dunstan, Hague, and Wheeler ( 6 ) . (55) Zanetti, Suydam, and Offner, J . Am. Chem. SOC.,44, 2036 (1922). (56) Zelinsky, Ber., 58, 185 (1925). (57) Zelinsky and Pavlov, Ibid., 66, 1420 (1933). RECEIVEDMay 13, 1935.
Production of Gasoline bv Polvrnerization of Olefins J
J
C. R. WAGNER, The Pure Oil Company, Chicago, Ill.
Gases from low-pressure vapor-phase cracking containing 20 to 24 per cent of ethylene, 13 to 18 per cent of propylene, and 6 to 10 per cent of unsaturates in the fourcarbon group were polymerized to liquid products by heat and pressure in the absence of catalysts. O n a once-through basis 1.7 gallons of gasoline per thousand cubic feet were obtained operating at 950" F. and 800 pounds pressure; the yield was increased to 3.0 gallons by recirculating the gas derived from stabilizing the liquid products. The yields were improved in a commercial unit to 3.23 gallons. By processing gas from stabilizing vapor-phase cracked distillates.
9.0 gallons were obtained. By operating at low pressure and 1200' to 1300' F., the liquid products were mostly aromatic.
I
S THE operation of low-pressure, vapor-
phase cracking processes a considerable quantity of fixed gas is produced. Based upon the gas oil content of the charging s t x k , t,liis gas yield usually runs from 20 to 30 per cant, depending upon the temperature a t which cracking takes place and the character of the fuel oil or residue produced. As pointed out already,' the characteristics of this gas are remarkably uniform for a n-ide range of charging stocks. Only one or tw:) grade? of charging stock have been found that' give off gases very different from those described, and in these instances methane and 1 Osterstrom, R . C . , and Wagner, C . R., paper presented before 10th annual meeting, Am. Petroleum Institute, December 4, 1929.
934
INDUSTRIAL AND EKGINEERING CHEMISTRY
I'OL. 27, KO. 8
'
p r o p a n e seem t o effective catalybts in this reaction. I t has been assumed that hare taken the place such is not the case, although certain considerations point of a p a r t of t h e to the fact that the carbon, a t least, may be very active. ethylene and proIn the first arrangement used on a semi-works scale, the pylene. In T a b l e gases were passed under the desired pressure through a heating I are given analyses coil into an insulated reaction chamber and thence through of several gases proa cooling coil, reducing valve, and separating drum where duced by the vaporcondensed material was measured after weathering. This phase cracking of operation was, therefore, on a strictly once-through basis. different c h a r g i n g The gas being handled was like that shown in column 2 of stocks. G a s o l i n e Table I. One of the first things noted was the strongly exoI d I hvdrocarbons were thermic nature of the reaction. While this had been expected from theoretical considerations, it was thought that the small GALLONS GASOLINE PER, THOUSAND C p . F T not re0 0.5 1.0 1.5 moved from many size of the unit (handling about 5 cubic feet of free gas per minute) would insure enough radiation to prevent a dangerFIGURE1. RESULTS OF TESTSox .4 Of these s a m p l e s , ONCE-THROUGH BASIS but the results of ous temperature rise. It was not foreseen that the temperature would go very quickly to 1100" to 1200" F. if not condrying them comtrolled, resulting in a dangerous deformation of the reaction pletely can readily be calculated. Temperatures employed chamber. in the cracking operation varied from about 1060' to 1128" F., and, a t least during this range, the effect of temperature upon Several runs were made with this equipment under varythe composition of the gas was negligible. ing conditions of temperature and pressure. Some of the results are given in Table I1 and are graphically represented The four-carbon fraction was studied rather carefully and in Figure 1. As was to be expected from a theoretical study appears to be fairly uniform. Its approximate composition is 60 per cent 1-butene, 25 per cent isobutene, 13 per cent 1,3of the problem, increasing the pressure increased the yield and the speed of the reaction. Increasing the temperature inbutadiene, and a 2 per cent mixture of n-butane and kobutane. This analysis, taken t oge t h e r DRY G A S with the comparative ease of separation RECIRCULATION GAS / of ethylene and propylene in a high state f of purity, has attracted considerable interest in such gases as a source of raw material for organic synthesis. It was early recognized that organic chemicals would not give an outlet for all the gases produced by such cracking processes, and consideration was, therefore, given to c o n v e r t i n g them into other useful products. The only outlet that seemed to be large enough to absorb the production from the many billions of cubic feet of refinery gases p r o d u c e d annually was the gasoline market. While the synthesis of p r o d u c t s of higher molecular weight by means of halogenation and then splitting out the halogen with alkali metal might be used, i t w o u l d b e t o o e x p e n s i v e a process when gasoline sells for 3 to 5 cents a FIGURE 2. FLOWSHEETOF POLYMERIZATION PLANT gallon. Catalytic po 1y m e r i z a t i o n , using carefully selected and specially creased very rapidly the speed of the reaction and the producprepared catalysts, may eventually become the best method tion of carbon and also altered the character of the confor accomplishing this result. In this paper, however, will densed product. be discussed only that phase of the problem covering the use The data in Table I1 point conclusively toward the use of of heat and pressure. There is always the possibility that the higher temperatures and pressures of the order of 800 to the steel walls of the heating elements and reaction coil (to1000 pounds in order to secure maximum yields. It was gether with the powdery coke formed in them) may act as
I
,,,]
'
-
I \
TABLEI. GAS ANALYSES Charging etock
Corning Gas Oil
Cabin Creek Gas Oil
Mexican Gas Oil
35.4 22.8 13.2 18.0
35.0 24.6 11 9
38.6 22.8 11.9 12.5 6.1
18 0
2.5
Nujol 45.6 29.8 9.4 11.8
Seminole Topped Crude
Polymersa
37.5 20.3 12.6 12.3 8.6 8.6
48.4 14.2 12.3 12.6 2.8 7.4 2.3
SpindleMidMt. Midtop continent Pleasant continent Topped Topped Topped Heavy Topped Crude Crude Crude Naphtha Crude
i:4 0:9 8.1 4.7 .. .. Ca and heavier 2.9 3.1 a Polymerized products from the fuller's earth treatment of vapor-phase cracked distillate. b This gas sample was taken when cracking at 1275' F. C Wet gages before extraction of any gasoline fractions.
G4
38.8 20.3 13.2 13.1 5.7 6.4 2.5
33.2 26.7 12.8 16.2 4.0 5.9 1.2
24.4 23.1 12.5 14.9 6.1 10.9 8.1C
29.6 23.1 12.8 13.3 4.9 8.3
s.oc
28.5 23.1 11.1 15.7 4.4 10.1 7.1c
Vans Gas Oil 34.7
22.6 15.3 17.9 i:9 1.6
INDUSTRIAL AND ENGINEERING CHEMISTRY
AUGUST, 1935
TABLE II. Run No. Pressure, lb./sq. in. Temp., O F. Gas, cu. ft./min. % olefins, fresh gas olefins, spent gas asoline, ga1./1000 cu. it. Tar, ga1./1000 cu. f t . Run No. Pressure, Ib./sq. in. Temp., F. Gas. cu. ft./min. % olefins, fresh gas 70olefins, spent gas Gasoline, ga1./1000 cu. f t . Tar, ga1./1000 cu. ft.
8
3
3
so0
so0
647 5 53.1 49 3 0.19 0 04
io!
J
52.0 49.8 0.42
0.08
22
800 811 5 51.1 48.0 0.72 0.Oi
14
15
800
800
854 7.5 52.0 48.3 1.17 0.09
756 10 51.7 50.3 0 19
0.03
TESTS ON 20
800 901 5 51.3 43 4 1.32 0.11 16 800 809 10 52.2 50.2 0.39 0.04
noted that the most strongly exothermic reactions occurred in these same ranges. Since the unweathered condensate appeared to contain a large volume of propylene and butylene, it was considered pobsible to increase the yield and a t the same time increase the amount of heat liberated by recycling these fractions through the reaction zone. Accordingly, the apparatus was enlarged and modified; in this form the flow of gas was essentially that shown in the flow sheet (Figure 2 ) . With this arranger ent much higher yield.. were obtained, and it \vas possible to control more accurately the quality of the product. In run 209, for example, a pressure of 1000 pounds per square inch was maintained on the system and a temperature of 915" F., with a recirculation ratio of 1.43. The fresh gas contained 50.9 per cent olefins, the spent gas contained 15.4 per cent olefins, and 3.0 gallons of gasoline per thousand cubic feet of fresh gas were recovered in spite of a loss of 14.2 per cent due to leaks, operation of safety valves, drawing of samples, etc. Yields of this order were not immediately secured, as there were many other problems to be solved in order to obtain steady operating conditions. It was necessary to remove carefully all hydrogen sulfide, or it would have combined with the olefins to form mercaptans. A uniform admixture of recirculated gas and fresh gas had to be delivered t o the reaction zone, or temperatures and yields would have fluctuated widely. Since this gas a t 1000 pounds pressure has a density nearly the s a m e a s t h e liquefied gases and condensate delivered to the accumulator, ordinary l i q u i d lerel controllers do not operate easily. Special gage glasqes had to be secured, means developed to prevent freezing of lines where pressure3 were reduced, and numerous other difficulties worked out. One of t h e o b v i o u s problems was to deterFIGURE3. EFFECTOF RECIRCU- mine the most satisfacLATION AND TIME tory time of reaction. Since the teinDerature employed was in the cracking range, decomposition i n d coke formation were to be expected along with polymerization of the olefins into heal-ier compounds. Without attempting t o >how individual runs on the graph, Figure 3 gives the effect of recirculation as well as the effect of time. These figures were obtained when working on gas from the cracking of dpindletop crude, which Contained from 42.5 to 47.5 per cent
935
ONCE-THROUGH BASIS 40 800 951 5 51.7 40.4 1.72 0.22 17
800 850 10 53.5 50.3 0.68 0.07
8
9
600 672 5 49.6 50.0 0.09
..
600 713 5 49.9 50.5 0.11 0.01
18 800 900 10 52.1 48.3 0.93 0.07
29 800 852 10 51.2 49.7 0.70 0.08
10 600 764 5 50 5 49 3 0.18 0.02 30
800 898 10
53.6 50.0 0.92 0.10
11
12
600 853 5 50.0 46.9 0.86 0.09
13
800 758 7.5 50.5 50 4 0 35
0.04
41 1000
so0 802 7 50 48 0 0
42
5 2
1 65 06
43
887
7.5 52.2 45.7 1.46 0.15
olefins. Figure 4 shows the effect of varying time when working on a gas made by cracking Midcontinent crude, which averaged between 47.5 and 52.5 per cent olefins. A small commercial unit utilizI80 ing this procedure was then cons t r u c t e d a n d o p e r a t e d for a 1 p e r i o d of y e a r s . Many new a n g l e s of the problem were discovered, some rather startling to the person who has grown accustomed to the whims of tube stills 100.- F Y and high-pressure liquid-phase z cracking units. As an example, 0 the attempt of an operator to halt 80.w a rise in temperature occurring in the stream of polymerizing gases 60m a y b e cited. Reasoning that 40.this temperature could be reguY I E L D - G A L L O N S OF lated as in tube still practice, he GASOLINE PER THOUSAND 2o increased the speed of the compressor, thus forcing 15 t o 20 percent FIGURE4. EFFECTOF T~~~ ON G~~ FROM more gas through the unit. The CRACKEDMIDCONTI- temperature jumped in less than NEXT CRUDE 2 minutes from ri40" to considerably o v e r 1300" F., t h e u p p e r limit of the recording pyrometer. Muffle temperatures in the tube still were not that high; hence, it was plain the rise was not due to better heat transfer alone. A view of this plant is shown in Figure 5 . In this unit the opportunity arose to work with gases containing varying proportions of total olefins as well as a range in the ratios existing between the percentages of individual olefins and the percentage of total olefins. There were two sources of gas for use as charging stock, the one a very dry gas from the absorber, the other the gas used as a reflux on the stabilizer at the gas recovery plant. The characteristics of these two gases are as follows:
1
Gas from -4bsorber
CH4, H2, etc. CzHk C2HB C3H6 C3Hs
C4 compounds Cs compounds and heavier Specific gravity
37.9 25.6 13.8 16.8 3.1 2 8
....
0.993
S1.abiliser .Reflux 4.2 1.6
...
I
27.1
....
66.5 0.6 1.500
The results of extended investigation showed that for this unit, pressures of 600 to 800 pounds are as satisfactory as the higher pressures, and under such conditions much better control is possible. In this pressure range and with a reaction temperature of 975" t o 1000" F. a recirculation ratio of 1.5 yields 3.23 gallons of condensate per thousand cubic feet when operating on gas from the absorber and 9.00 gallons when charging stabilizer reflux. Mixtures of the two give yields that may be calculated arithmetically from the proportions of the mixtures.
INDUSTRIAL AND ENGINEERING CHEMISTRY
936
Table I11 gives the analysis of two gases used as charging stock together with the analysis of the processed gas produced a t the high-pressure gas separator. The effect of entrainment is clearly shown, emphasizing another of the design problems involved.
TABLE111. ASALYSESOF Source of gas Size of polymerization unit, cu. f t . / d a y Pressure, lb./sq. in. Temp., ' F. Recirculation ratio
Mexican ga3 oil
600,000 650 1000 1.3
15,000 1000 900 2.6
Fresh gas 24.2 17.9 12.7 37.2 4.1 3 8
CHI, Hz, etc. C~HI CzH6 CaHe CsHs C Pcompounds CScompounds Sp. gr. Hydrogen
GASES
Topped Midcont?nent crude
....
1.124 2.1
Processed gas 41.3 2.0 24.6 21.0 7 7 2.6 0.9 0 964 2 8
Fresh gas 38.5 22.9 11.9 12.5 6.1 8.1
....
Processed gas 62.6 11.6 14.7 2.0 7.0 2.1
0.977 6.8
....
0,772 14
Fuel consumption in this small commercial unit averaged between 5 and 6 per cent of the charge. In a larger unit it would be materially less. A time efficiency of about 90 per cent was obtained over a period of months of continuous operation. The following table gives representative tests on the condensate as produced and on the gasoline recovered by treatment of the condensate. Con- Gasodensate line 56.5 92 128 146 166 182 201 222 248 280 328 398
Condensate 8.7 11.5
Residue Reid vapor pressure Sulfur .. Octane No.: C. F. R . research method . . A. S.T. M. method ..
Gasoline 1.0 10.0 Trace
96 78
VOL. 21, NO. 8
about 5,000,000 cubic feet of gas per day. The olefins were concentrated by selective absorption and charged to the unit as a liquid under 600 to 800 pounds pressure. Under these conditions with very little ethylene present, it was found unnecessary to remove hydrogen sulfide if the reaction was carried out around 1025" F. It is probable that high temperatures would cause fixation of sulfur, but relatively little difficulty was encountered a t the temperatures mentioned. When operating a t capacity, this unit produced an average of something over 400 barrels (42 gallons) per day of gasoline boiling point material. Because of the marked sensitivity of gasoline produced by this process, it was considered desirable to repeat some experiments performed very early in this investigation. In these tests olefin-bearing gases were heated quickly t o 1100" F. or higher and then allowed to rise in temperature because of the exothermic heat of reaction until a final temperature of 1200" to 1300" F. was reached. In this manner it was possible to produce a highly aromatic distillate from which gasoline having an octane number (A. S. T. M.) of approximately 100 could be produced. It was also possible to produce relatively pure aromatic hydrocarbons by simple fractionation after treatment with 2 to 4 pounds of sulfuric acid per barrel. The following table gives characteristics of the aromatics separated; these compounds are sulfur-free, because of the absence of sulfur in the gas treated: Sp. gr. a t 15' C./4' C. Freezing point, C . ( " F.) Boilingpoint, ' C. (" F.) Refractive index a t 20' C. a Melting point.
Benzene Toluene Naphthalene 0.877 0.865 4.7 (40.5) -97 (-142.6) 8O:O (176)a 79.8 (175.6) 110 (230) .. 1.4994 1,4940 ..
A rough calculation based upon the yields obtained in these preliminary experiments indicates that refinery gases now available in the United States, if all were treated as in these tests, would produce about 1,000,000,000 gallons per year of aromatic hydrocarbons.
Acknowledgment
As a result of the work done on this small commercial unit, a larger plant was constructed to handle the olefins from
The author wishes to express his appreciation of the careful work of P. A. Maschwitz throughout this development. To a large degree the successful outcome of the work is a result of his efforts. RECEIVED M a y 6, 1935
FIGURE 5. S~IALL CONMERCIAL UNIT
