I N D U S T R I A L A ND E N G I N E E R I N G C H E M I S T R Y
1120
pigments, respectively), indicate that carbon dioxide gas may be formed by the bacilli under these circumstances. It is common knowledge that omission of nitrate in curing chopped hams will result in finished canned products which do not show the usual fermentative carbon dioxide swells. Upon incubation at 37.2' C. the reduction potential of such a product meets the requirements for optimum conditions for growth of Clostridia and other anaerobic forms. This type of spoilage, not often rewlting in swells, impresses everyone with the need for sufficient nitrate in the cure. Kitrate, according to a new concept of potentials, is an oxidizing agent ( 3 ) . It is an easily proved fact that nitratenitrite-salt-sugar cure favors most races oi aerobic bacteria, whereas nitrite-salt-sugar cure always inhibits fermentation and aids in putrefaction. CRITERIA
SAXITART QU.4LITY OF CANXED SPICEDHAMS As shown in this work, incubation of cans at 37.2" and 48.9" C. affords no certain data for judging the sanitary qualities of this food. Cans of meat prepared from practically sterile trimmings but spiced with contaminated spice or wrapped with contaminated paper will swell when incubated a t 37.2" and 48.9' C. Trimmings showing five to ten per gram of the bacilli OF
Vol. 26, No. 10
described and a total count (of all viable microorganisms) of one hundred per gram will give a canned product that swells after several days of incubation, whereas trimmings showing no ('carbon dioxide gas bacilli," but having an initial count of ten million bacteria per gram may give a product that will not swell in 90 days at 37.2" C. Hence incubation tests of these products should be supplanted by direct bacteriological examinations of the meat from aseptically opened cans. Since we have a medium to detect the bacilli responsible for gas production, obviously we can find them and eradicate them from the environment of processing. With trimmings free from these bacteria, sterilized spices, and microbially clean wrapping paper, a spiced ham may be produced with nitrate-nitrite-sugar cure that will not swell at 37.2' and 48.9" c. LITERATURE CITED (1) Bergey. Manual of Determinative Bacteriology, 4th ed., Williams 8;: Wilkins Co , Baltimore, 1934. ' 2 ) Jensen,L. B . , e t a]., J. Bact., 15, 367-450 (1928); Collected Papers Mayo Chnzc, 1930. 898-900; .J. Inf~ctiousDiseases, 52, 167-
85 (1933). 13) Stephenson, Marjory, "Bacterial Metabolism," p. 74, Longmans, Green &- Co., New York, 1930.
RECEIVBDJune 8 , 1934
Lubricating Oils from Ethylene R. G. ATKINSON AND H. H. STORCH, U. S.Bureau of Mines Experiment Station, Pittsburgh, Pa.
T
KE a m o u n t of olefins analysis in an Orsat apparatus The experiments described below indicate p r e s e n t i n commercial (in volume per cent): that it should be possible to produce a good gases m a y exceed two Oxygen 0.39 "light" lubricant f r o m the lower members of Nitrogen 1.60 billion cubic meters per year. Saturatea 1.00 the olefin series by a two-stage process, the first In addition, an enormous supply Ethylene 97.11 slep being a thermal polymerization to a liquid of olefins is obtainable by dehyFigure 1 is a flow sheet of d r o gen a t ing paraffinic gases boiling in the gasoline range. The material t h e a p p a r a t u s in which the (6,7). I n a review of the literathermal polymerization was acproduced in this manner can then he polyture on olefin polymerization, complished. merized by aluminum chloride to a viscous liquid Egloff, S c h a a d , a n d Lowry It consists of a cylindrical suitable f o r a lubricant. (3) have estimated the potenalloy-steel bomb 1.35 liters in While there are not enough data available tial production of olefins from volume, copper- pl a t ed inside. natural gas, cracking still gas, Three tubes enter through conto enable one to predict anything about the nections on the head of the bomb. waste gas from natural gasoline commercial applicability of the process, it is One serves as a thermocouple plants, and other refinery gases well, one t o conduct the incoming thought that further investigations should prove to amount to f o u r t e e n billion gas to the bottom of the bomb, of value. cubic meters in one year. Findand t h e third t o remove t h e polymerized gas and vapors from ing a means of more profitable udization of olefinic gases in large quantities is of much the top of the bomb. The outlet tube leads t o a coil cooled with iced water, immediately under which is a trap to catch the concern to the industrial chemist. condensed liquid. The pressure is reduced at the outlet of this Lubricating oils obtained by polymerizing ethylene with trap. The wet gas from the trap is led through another trap aluminum chloride have been investigated by Nash, Stanley, chilled with carbon dioxide snow and then through a column and Bowen (4), and also by Sullivan, Voorhees, Neeley, and packed with activated charcoal. The autoclave was heated to 371" C. and maintained at this ShankIand (9), who reported these Iubricants to have a very temperature throughout the experiment. Ethylene was let inferior viscosity-temperature coefficient. The latter authors into the system rapidly until the pressure built up t o 70.6 kg. have shown that the viscosity index (1) of an oil produced by per sq. cm.; then the valve controlling the outlet was cracked, and a constant rate of flow through the gas meter was mainpolymerization increases proportionally to the length of the tained. After 60 minutes the flow of gas was stopped, and all straight carbon-atom chain in the starting material. Hence liquid products obtained were collected. it was thought advisable to investigate the possibility of obThe data for seven experiments are listed in Table I. taining a good lubricant by first polymerizing ethylene thermally to liquid of low molecular weight and then treating Column 7 gives the volume per cent of the residual gas this material with aluminum chloride to yield a viscous liquid. absorbed by 1.6-gravity sulfuric acid. The absorbable material was thought to be largely propene. PRODUCTION OF LIQUIDBY THERMAL POLYMERIZATION It was observed that, when the reaction temperature was is, Commercial-grade ethylene was used throughout the in- 410" C. or higher, the ethylene usually "flashed"-that vestigation. A 587-cc. sample of the gas gave the following reacted very rapidly as evidenced by a sudden rise in pressure
I N D U S T 1%I A L
October, 1934
AKD
E N G IN E ER I N G CH EM ISTR Y
and temperature (from 410" to about 800" C. in a few seconds). The temperature a t which this flashing occurs seems to depend upon the rate of heat conduction of the apparatus, for Dunstan, Hague, and Wheeler ( 2 ) report 460" C. as the flash point for ethylene a t 56.2 kg. per sq. cm. pressure in a
Cundenw
TIONOF
POLYMERIZATION
No.
RUN Minutes
1 2 3 4 5 6
60 50 85 60 58 57 60
7
OFF-GAS At Absorbed standard by 1.6 TEXP. P R E B S U RPOLYMER ~ conditions HzSOi C. K g . / a p . cm. Grams Liters Vol. % 1.0 40.3 335.0 371 70.6 31.0 238.2 1.0 380 54.7 104.7 363.4 0.4 393 62.2 227.0 1.0 62.2 82.1 390 48.8 229.5 0.7 390 48.8 249.6 0.4 67.2 111.1 392 249.0 0.7 68.5 132.6 393 CON-
h S .
DEN0ED
CHARACTER OF PRODUCTS. The pale yellow oil recovered from the condensate trap had the greenish fluorescence characteristic of many petroleum oils. It was a highly unsat,urated oil having a bromine number (by method of Francis) of 1.29 grams per gram. Upon simple distillation the oil boiled over uniformly from 20" to 300" C. Usually about 50 per cent of the oil had passed over when the temperature reached 150" C. The character of the oil produced did not change markedly with limited variations. in temperature and pressure. A tendency was observed for the average molecular weight of the liquid produced to increase with increase of temperature, time of contact, or pressure, but its increase was not as pronounced as the increase in amount of material produced. The liquid recovered from the charcoal and the carbon dioxide snow trap had characteristics similar to butene. An Orsat analysis of the residual gas from run 6 was as follows (in per cent): Carbon dioxide Pro ene and butene H yfrogen NItrogen
0.15 0.4 Nil 2.6
Oxwen M c t h n e and ethane Ethylene
0.1 1.8 94.95
Inspection of the analysis shows that there would be no objection to compressing the gas and recirculating i t a number of times. DISCUSSION OF THERMAL POLYMERIZATION The primary step in the polymerization (C2Hs C,Hd = GHs) is a reaction of the second order (6),but the percentage of ethylene reacting was not accurately proportional to the pressure in the experiments described below. For example, it was observed that a pressure drop of 3 per cent (corresponding to 6 per cent reaction) occurred in 12.5 minutes at 16.2
+
ETHYLENE POLYCONVERSION
(XONCATALYTIC) POLYMERIZATION OF TABLEI. THERMAL ETHYLENE MENT
OF
MERIZATIOTi
2.5-cm. copper-lined tube. The copper-plated bomb used in the experiments of Table I was 7.5 cm. in diameter.
EXPERI-DURA-
kg. per sq. em. absolute pressure and 385" C. At 385" C. and 65.8 kg. per sq. cm. absolute, a 3 per cent pressure drop in 4 minutes was observed. On the basis of a second-order reaction, the rate of pressure decrease a t 65.8 kg. should have been 3 per cent in 3.03 minutes. Part of the discrepancy is probably related to other phenomena described under the heading "Oxygen Effect." Since this effect apparently decreases at the higher pressures, it is possible to predict approximately the change in rate of polymerization with respect to pressure over moderate ranges of pressure. Figure 2 shows the percentage of ethylene polymerized to 1 liquids us. 1000 X " K. plotted t o semilogarithmic scale, the data being taken from Table 11. The slope of the line shown on the graph represents a heat of activation of 39,600 calories. This agrees fairly well with the value Storch (8) obtained a t 2 atmospheres, using ethylene from which he had taken pains to extract the minute quantity of oxygen present. T.4BLE 11. TEMPERATURE COEFFICIENT
Dewar fimk filled ivith COn snow and CIHjOH
FIGURE1. FLOWSHEET OF THERMaL PROCESS
1121
TIMEOF COXTACT Minutes 7.14 6.44 7.95 9.21 6.75 8.60 8.80
EXPT. 1 2 3 4 5 6
7
CONDENSmD
PER MIN. AT 70.3 KQ./0Q. CM.
8.76 9.40 18.67 22.38 14.50 26.19 29.80
1.221 1.874 2.656 2.749 3.095 3.185 3.477
POLYMER 70 bu wt.
T ( " K.1
1.5528 1.5314 1.5015 1.5083 1.5083 1.5038 1.5015
PRESBURE
%
The data of Table I1 have been calculated from Table I by assuming that the molecular weight of the liquid product was equal to 54 (mean boiling point'2).
+
2?
3P I I
E2
%
2
i: za
1%
151
152
153
154
I F
156
1QQP-
E4 FIGURE 2. PERCENTAGE ETHYLENE POLYMERIZED us. (1000/T)
OXYGEN EFFECT. I n the paper cited, Storch (8) has reported that a t pressures of 1 and 2 atmospheres very minute quantities of oxygen in the gas greatly affect the velocity with which the reaction proceeds. The results of some experiments given here indicate roughly the extent of the oxygen effect. The value for oxygen content (0.39 per cent) given in the gas analysis is possibly high; however, t h e true value is probably between 0.2 and 0.4 per cent. A reaction vessel at 380" C. was thoroughly flushed out, evacuated, and then filled to a pressure of 150 cm. of mercury absolute. Polymerization took place a t such a rate that the pressure decreased 3 per cent in 55 minutes. For a second experiment ethylene from the tank ww kept in contact with a deoxidizing solution of sodium hyposulfite for 15 days. A t the end of this time the bomb was filled as before and the rate of reaction was such that 100 minutes were required for a 3 per cent pressure drop. Under similar conditions ethylene treated with sodium hyposulfite for 30 days showed a 3 per cent pressure drop in 130 minutes. ALUMINUM CHLORIDE POLYMERIZATION Viscous liquids suitable for use as lubricating oils were obtained from the low-boiling polymer by treating it with aluminum chloride at room temperature. The treatment wm carried out in a cylindrical mill of 2.25 liters capacity, which
b
I N D U S T R I A L A N D E N G I N E'E R I N G
1122
was rotated continuously a t a speed of 40 r. p. m. to provide agitation. The results of two typical runs are given in Table 111. After 48 hours the contents of the agitator were filtered to remove all suspended matter. The spent aluminum chloride which remained on the filter had a very dark viscous oil combined with it. This material is referred to as bound oil to distinguish it from the free oil found in the filtrate.
0
PERCENT OVER
FIGURE 3. COMPARISON OF DISTILLATION RESULTS The filtrate was washed with water, then with caustic, and again with water. The free oil was separated from the diluent naphtha by distillation a t atmospheric pressure. Figure 3 shows the results of a distillation of the free oil and naphtha compared with a distillation of the naphtha used as a diluent. I n run 1 the atmospheric pressure distillation was stopped when the temperature reached 220' C., and the residue was reduced under vacuum until 182 cc. of oil remained. This 182 cc. (30.3 per cent of the original thermal polymer) of oil had the viscosity characteristics indicated in row A (Table 111) when measured with a Saybolt Universal viscometer. The 182 cc. of oil described above were further reduced under vacuum to a volume of 122 cc. which gave the viscosity reading shown in row B. Run 2 yielded after distillation 120 cc. of oil of viscosity characteristics given in row A (Table 111). The 120 cc. of free oil were further reduced under vacuum to 89 cc., which gave the viscosity readings shown in row B.
c H E M I sT R Y
Vol. 26, No. 10
the diluent naphtha contained considerable quantities of unsaturates. The bound oil produced by aluminum chloride treatment was liberated by decomposition with iced water. This oil was highly unsaturated and very dark, and sediment continued to settle out of it over an extended period of time, It had a viscosity index of 27. Inspection of the above results shows that, as the viscosity of the synthetic lubricant increases, its viscosity index decreases. This relation might have been predicted by assuming that, as polymerization proceeds, the molecules produced become more naphthenic in character; that is, there are fewer straight carbon-atom chains and more branch chains, ring compounds, etc., in the more highly polymerized molecules, The viscosity indices of the oils reported here compare favorably with that of - 150,which was obtained by Sullivan, Voorhees, Neeley, and Shankland by treating ethylene with aluminum chloride. However, the lubricant reported by them was much more viscous. A comparison of treating only the lighter fractions of the initial polymer with aluminum chloride against treating all the thermal polymer produced shows the latter method to be advisable. Table I11 reveals that in the second case the viscosity-temperature relationship of the material produced is slightly favorable. Also, the yield of viscous oil is slightly better in the second case. Since the low-boiling material distilled off after the aluminum chloride treatment contained considerable unsaturates, the yield of heavy oil produced could probably be increased by using the material distilled off as a diluent in treating additional liquid polymer produced thermally. While no mechanical tests for lubricating efficiency were made in this investigation, the character of the oil in this respect should be similar to that of the ethylene polymer investigated by Nash, Stanley, and Bowen (4, who found no objection to the lubricant from the oiliness standpoint. It seems possible that the bound oil that was liberated from the aluminum chloride might be converted into a fair lubricant by hydrogenation. ACKNOWLEDGMENT The senior author (R. G. Atkinson) wishes to acknowledge the help of R. L. Abel, Petroleum Refining Department, University of Pittsburgh.
LITERATURE CITED TABLE111. ALUMINUMCHLORIDE POLYMERIZATION (1) Davis, Lapeyrouse, and Dean, OiZ Gas J . , 30, 92 (1932). (At 25O C., atmospherio pressure, 48-hour contact time) (2) Dunstan, Hague, and Wheeler, IND.ENQ.CHEM.,26,300 (1934). c CHARG~ YIELD (3) Egloff, Schaad, and Lowry, J . Phys.Chem., 35, 1825-1903 (1931). Ethylene Polymer Ethylene Viscosity (4) Nash, Stanley, and Bowen, J . Inst. Petroleum Tech., 16, No. 86, RUN B. P. PolyViscosity at: Index
-
No.
range Volume Naohtha AlCL 0
1A
B 2A
6. ..
~ c .
mer5 looo F.6 210° P. ( 1 )
&.
aroma
o/, .-
sac.
Sec.
40
30.3 20.2 35.3 28.2
155 532
44 68.5
0-150
600
1030
28-300
340
600
108 51
208 46.6 91 B 710 65 58 Crude product from AlCls polymerization wa8 reduced by distillation. ,b loOD F. 37.8O C.; 210° F. = 98.9' C.
Q
-
30
830-69 (1930). ( 5 ) Oberfell and Guyer, Am. Petroleum Inst. BUZZ.,June, 1932,p. 32. (6) Pease, J . Am. Chem. SOC.,53, 613 (1931). (7) Podbielniak, Oil Gas J . , 29, No. 52, 22 (1931). (8) Storch, 3.Ana. Chem. SOC.,56, 374 (1934). (9) Sullivan, Voorhees, Neeley, and Shankland, IND. ENO. C H ~ M . , 23, 604 (1931).
RIOCIOIVED July 11, 1934. Published by permisaion of the Direator. U. S.
'The oil of 710 viscosity a t 100" F. (37.8" C,) had a pour of -200 F. (-28.90 c.). ~thad a good color and was Of rather saturated the lighter constituents taken from the agitator and distilled off along with
Bureau of Mines, and submitted to the faculty of the University of Pittsburgh by R. G. Atkinaon in psrtial fulfilment of the requirements for the doctor's degree. (Not subject to copyright.) R. 0.Atkinson'6 present sddresa is Pure oil Company, Chicago, Ill.
While the United POTASH FERTILIZER EXPORTS INCREASING. 'States is one of the world's largest importers of fertilizers and fertilizer materials, it is able as a result of certain transportation advantages to export substantial quantities of potash fertilizer, according to the Chemical Division of the Department of Commerce. This situation is particularly true as regards California, where large deposits occur in natural brines.
During the first haIf of 1934, United States exports of potash fertilizer amounted to 15,840tons, valued at $627,000,compared with 25,080 tons, valued at $902,000,for the entire year of 1933, and 1816 tons, valued at $70,000, for the calendar year 1932. In addition, 6440 tons were shipped t o Hawaii and 6350to Port0 Rico during the first half of 1934. Japan took approximately 80 per cent of our total shipments abroad.
