870
INDUSTRIAL AND ENGINEERING CHEMISTRY
cqwz t,n that niyuired for eomprossion;
hencc, Lhc stcam requird for stripping is praetieslly only that which i3 condensed because o f heat losses in tho system. The glycol-water product from the muhbing column contains approximately 8% butylene glycol and is easily rectified to make a product conCainiw99% butylen(: dyeol.
graWully : ~ k n o w l ~ d Tlic ~ d atoam c y d e of the. stripping and
scrubbing c,olumns wns zugacsted by E. R. Gilliland. LITERATURE CITED
(2) G3i
ACKNOWLEDGMENT
Thc: cooperation of Joseph E. Seneram S. Sons, Ioc., in furni inr m m ? of the rvnporator sirup used in t,hia invrst.ige.tion is
Vol. 31, No. 9
(4)
(6)
hlu3tnkuj, c, c,, Eiron, Asron, I ) , I_ , Is”. EN^. CHEM., 37.870 (1045). Chute. H. 0..U. S. Patent 963,275 (July 5, 1910). Northern Repiond Research Lab., unpob. data. Raioh, 0. T., Chem. B Md. Eno., 49 (51, 129 (1942). Ward, G. E., Pettijohn. 0. G., Lockwood. L. R.. and Cognill It. D.. J . Am. Clam. Soc., 66. 541 (1944).
LIQUID-VAPOR EQUILIBRIUM in MIXTURES of 2,3-BUTYLENE 6LYC01 and WATER R.
n. BLOM,
G.
c.MUSTAKAS,
AARON E F R O N , A N D D. L. REED’ NORTHERN REOIONAL RESEARCH LAEORATORY.
u. $5. CGPARTMENT O F
AQRICULTURC. PEORIA. ILL
Liquid-vapor equilibrium measurements have been made ing point approdrnetely 5’ C. below that of meso-glycol and unfor meso-2.3-butylene glycol-water system a t p r e . 6 ~ 1 ~ 5 doubtedly influencesliquid-vapor equilibrium results. However, and concentrations covering t h e ranges t o be encountered since the amount of dextrorotatory glycol present is sml~I1,it is In t h e recovwy of glycol from fermentation liquors. assumed that the effect on the res~iltais neglieble, particularly From these data a chart has been prepared which Shows for enginewing calculations. vapor composition as a funetion of pressure for certain Thedynamic arbitrarily chosen liquid concentrations. The chart has method, 8s dean aceuricy sufficient for engineering design aalcwlations. scribed by Othmer (St, ws8 used t o obtain HE proom described in the preceding paper far recoverin& equilibrium data. m~c-2,bbutylene glycol from fermentation liquor“ ( I ) inThe equipment volves concentration of beer et reduoed pccrisurea, followed by consisted of two steam stripping and vapor scrubbing at elevated pressures. The 0 t hmer equilibdesign of equipment necessaw to oarry out these operations end rium stills (3) other concentration and rectification steps by which a 99% constructed of butylene glycol product is produced is baaed largely on thc Pyrex and one liquid-vapor equilibrium of the butylene glycol-water system. pmsure equilibLiquid-vapor equilibrium dnta for the meso-2,3-butyleiie rium still conglycol-water system have been determined at 2.45 pounds per structed of stainsquare inch sbwlute (zqxoximately 25 inches of mercury vscless steel. One uum) and at stmasphorie pressures for ooncen1,rationsof 0 to 100 of the glass stills mole % glycol in the liquid. Data for pressures of 30 and f ~ 5 wm heated by B pounds per square inch gage have been determined for coneengas b e which trations of glycol in the liquid of 0 to 35 mole %. The grapti impinged on the obtained by cross plotting these data can be used to interpolat,. thermal circulaequilibrium values for the intermediate pressures and wneentmtion leg of the tions expected in the various steps of the glyool recovery process. boiler; the other contained 80 inMETHOD FOR EQUILIBRIUM DATA ternal electricTechnical @.de mo-2,3-butylcne glycol, recovered from an resistance heater. Aeramogmes fermentation of acid-hydrolysed wheat These a t a s were mash, was purified by distillation of a SO% solution of the glycol vented to a. g l w which hsd been autoolavod in the presence o f lime. The water manifold to which fraction wm removed st atmospheric pressure, and the glycol was were conneoted B then distilled under vacuum. The purified material waa colorless vacuum ballast snd had only B slight odor. While A. aerogenes produces butyltank, D m e r e ene glycol in which the m a varicty predominates (6). wme manometer,% deztreplyool is also formed. The latter eteric-ieamer has e. boilgluroe of VBcUum. and 8% atmosI Prarcnt n l l d r m . Pumt Sound Pulp and Timher Company. Bsllingham. Figure$. Equlllbrium Still for Uw p h e r i o vent.. Wad,. a t Elevated Pressures
T
September, 1945
INDUSTRIAL AND ENGINEERING CHEMISTRY
871
hour. As the volume of the distillate receiver and return tube was about 30 cc., a distillation ate of 0*/8 cycles per hour was achieved. The distillation was conducted for 1.5 to 3 hours, depending on the glycol content of the liquids; then samples of the liquid in both the boiler and distillate receiver were taken for analysis. The pressure still (Figure 1) is a large-scale adaptation of the glass stills, and consists of a boiler, condenser, distillate receiver, and pressureequalizing chamber. It is constructed of stainless steel, is equipped with needle valves and a ballast tank,and has an allowable working pressure of 100 pounds per square inch gage. A more detailed description of the still was given by Othmer (4). The liquid in the boiler was heated by a flame which impinged on the thermal circulation leg. To prevent partial condensation of the vapors, the upper portion of the boiler was wound with resistance Wire and electrically heated. Superheating of the vapors was avoided by careful control of the heat input. The entire boiler was insulated by an asbestos jacket. Pressure was indicated by a calibrated Bourdontype gage, and an iron-constantan thermocouple was used to determine the temperature of the vapor. The equipment waa evacuated, and then 800 cc. of liquid were drawn into the still. The entire system waa filled with nitrogen and again evacuated to remove any remaining oxygen. Nitrogen was then introduced until the desired operating pressure was reached and heating of the liquid commenced. When the liquid reached its boiling point, the pressure in the still was 0.04 00.10 0.0 0.4 Q6 08 1.0 2.0 4.0 6.0 IQQ 20.0 40.0 60.0 K)o again adjusted by either adding Or venting nitrogen. The rate of evaporation was approximately BUTYLENE GLYCOL IN LIQUID ,.MOLE % 420 cc. of liquid per hour. The capacity of the distillate receiver and return tubes was adjusted Figure 2. Liquid-Vapor Squilibriurn of Butylene Gfyool-Water Mixture8 to approximately 60 cc. by the insertion of a a t Various Pressures metal block in the receiver. Thus a distillation rate of 7 cycles per hour was achieved, The disThe glass stilk tillations were conducted for 2 to 3 hours, depending on the could, then, be glycol content of the mixture charged to the boiler, Srunples o p e r a t e d under were taken at the end of the distillation period and analyzed either vacuum or for their glycol content. atmospheric preeThe butylene glycoi content of samples containing less than 5 sure. A c e n t i weight % of glycol was determined chemically by a periodic acidgrade themomoxidation method. This method, based on the formation of 2 e ter w i t h 1 moles of acetaldehyde by the oxidation of 1 mole of 2,3-butylene graduations was glycol with periodic acid, will be described in a future publication. used to measure Samples containing between 5% and 94 weight % of glycol were the vapor tsmanalyzed by refractive index. Samples containing more than perature. A f t e r 94% glycol were analyzed for their water content by the method approximately of Karl Fischer (9). 300 cc. of glycolDISCUSSION OF RESULTS water mixture was charged Of
the
to the a
was adjusted Or the was vented
to the atmos-
ABSOLUTE PRESSURE,LB./SQ. IN.
Figure 3. Effect of Pressure on Eq u i Iibri um Cornposltion
PheW ami heating of the liquid commenced. The rate of evapomtion averaged a p proximately 200 cc. of liquid per
Table I presents results of the equilibrium determinations. Temperatures are reported for only a few points, since the accuracy of measurement was not sdEcient to detect consistently the small differences in temperature between many of the points. The equilibrium data were plotted and the resulting diagram is given in Figure 2. Logarithmic coordinates were used in order to avoid crowding the points at the lower concentrations. Figure 3 is a logarithmic cross plot of vapor composition against absolute preasure at a few arbitrarily chosen liquid concentrations. Straight lines were drawn to average the four points although some curvature is indicated st the higher pressures. However, in view of the experimental error and the fact that the equilibrium values were not all determined in the same apparatiis, it
INDUSTRIAL AND ENGINEERING CHEMISTRY
872
TABLE I. LIQUID-VAPOR EQUILIBRIUM DATA FOR MESO-BUTYLENE GLYCOLWATERMIXTURE
Butylene Glycol Mole T ~ ~ , . , Weight % in: Liquid Vapor Liquid -Pressure 750 * 5 Mm. 100.0 0.231 0.0244 0.0462 0.530 0.0535 0.106 1.06 0.112 0.214 2.00 0.226 0.406 0.886 4.28 0.470 6.90 0.733 1.46 0.920 1.90 8.84 1.09 2.36 100.5 10.8 3.46 15.2 1.45 7.08 2.68 101.0 27.6 3.40 12.1 101.8 40.7 50.7 4.57 17.1 5.95 103.0 58.2 21.8 69.4 7.66 31.2 105.0 70.0 7.00 31.8 8.40 106.0 73.7 35.9 11.8 58.6 109.3 87.6 113.4 90.3 65,l 16 8 72.4 117.0 92.9 22.5 81.7 134.8 95.7 45.7 158.5 98.8 94.3 76.1
-
Pressure 1.46 2.66 5.05 10.50 12.3 15.1 16.9 19.5 21.4 136.0 24.8 37.5 40.2 41.0 50.0 138.0 61.1 139.5 66.2 149.7 68.5 151.6 73.5 155.0 76.7
136.0
-
Yo in: Vapor
T.""d*
. -------Pressure 0.00486 0.0107 0.0224 0.0453 0.0944 0.147 0.185 0.220 0.293 0.548 0.699 0.948 1.25 1.63 1.48 1.80 2.61 3.88 5.49 14.4 38.9
Butylene Glycol Weight % in: Mole Liquid Vapor Liquid = 127 5 Mm. 0.423 0.0142 0'0847 0.700 0.0244 0.141 1.34 0.0430 0.271 4.58 0.153 0.950 5.05 0.160 1.05 14.7 0.500 3.33 15.8 0.460 3.62 30.1 0.900 7.93 40.6 1.60 12.02 58.7 2.92 22.1 69.0 3.16 30.8 69.7 3.56 31.5 73.7 4.10 35.9 85.5 8.20 64.1 91.6 15.2 68.6 93.3 19.0 73.6 93.6 40.9 74.5 96.2 63.4 83.5 98.6 79.3 93.4
58.4 58.5 59.0
60.4 63.0 64.0 71.0 74.0 81.0 92.0 106.2 118.0
30 Lb./Sq. In. GageP --resure 0.308 0.295 0.0617 154.5 0.585 0.543 0.117 0.222 1.10 1.10 2.19 0.446 2.28 2.60 0.531 2.73 2.82 0.577 3.43 3.26 0.669 3.89 3.62 4.61 1).745 156.0 4.01 5.16 0.828 4.61 6.19 0.957 6.40 1.35 10.7 7.20 11.9 1.53 7.10 1.51 12.2 156.5 8.60 1.85 16.7 2.32 23.9 10.6 11.9 2.63 28.1 30.3 12.8 2.85 3.31 35.7 14.6 16.2 3.72 39.7 157.8 159.6 160.2 170.5 172.2
yo in: Vapor
f
-
0.00280 0.00486 O.OO859 0.0307 0.0321 0.100 0.0924 0.181 0.324 0.598 0.648 0.733 0.848 1.76 3.46 4.48 12.2 25.7 43.4
65 Lb./Sq. In. Gage-0.0143 0.0352 0.139 0.208 0.351 0.412 0.449 0.707 0.671 0.805 0.899 0.948 0.931 1.10 1.14 1.24 1.66 1.92 2.10 2.17 2.27 2.61 2.80 2.88 3.41
Vol. 37, No. 9
is believed that the data are consistent and that the moderate scattering of the points in Figures 2 and 3 is not unreasonable. Figure 3 can be used to obtain1 equilibriwn values for aqueous solutione containing up to 35 mole % butylene glycol a t pressures varying from 2.45 to 80 pounds per square inch absolute. The equilibrium values so obtained are sufficiently accurate for use in making engineering calculations. ACKNOWLEDCMENT
The pressure equilibrium still wag made available for this work through the courtesy of the Vulcan Copper and Supply Company. The authors acknowledge assistance of the Analytical and Physical Chemical Division of this laboratory in making some of the analyses. LITERATURE CITED
(1) Blom, R. H., Reed, D. L., Efron.
Aaron. and Mustakas; G . C., IND. ENG.CHEM.,37, 865 (1945). (2) McKinney, C. D., and Hall,R. T.. IND. ENQ.CHEM.,ANAL.ED., 15.
.
460 (1943). (3) Othmer, D. F., IND.ENG.CEBIM., 35, 614 (1943). (4) Othmer, D. F., and Morley, F. R.. Div. of Ind. & Eng. Chem., A.C.S.. New York, Sept., 1944. ( 5 ) Ward, G . E., Pettijohn, 0. G..
Lockwood, L. B., and Coghill. R. D., J . Am. C h a . Soc., 66. 641 (1944).
CONTINUOUS PROCESS for ACETYLATION of 2,S-BUTYLENE GLYCOL HE development of a commercially feasible process for the
T
production of 1,3-butadiene from 2,3-butylene glycol depended largely on the adaptation of each step to continuous operation. It has been shown (4)that the pyrolysis of the glycol diacetate is a more efficient route to butadiene than the direct catalytic dehydration of the glycol. The pyrolysis operation, the separation and purification of the butadiene, and the recovery and rectification of the acetic acid and by-products (6) were all readily adaptable to continuous processing equipment. The oonversion of the glycol to its diacetate by continuous methods, however, required a more detailed investigation. Continuous esterification processes now in commercial operation are confined almost wholly to the manufacture of esters which can be removed from the reaction mixture by distillation. Since 2,3-butylene glycol diacetate has a boiling point of 193' C. and its water azeotrope (boiliig point, 99.5' C.) is not readily separable from acetic acid, its manufacture was not adaptable to these systems (3).
ESTERIFICATION REACTIONS
The mineral-acid-catalyzed acetylation of 2,3-butylene glycol may be illustrated by the following equation:
This reaction probably proceeds in two steps with the intermediate formation of the glycol monoacetate which is found to be present in the acetylation mixture in an amount inversely proportional to the degree of completion of the reaction. In addition to the main acetylation reaction, several side reactions may also occur. A small amount of methyl ethyl ketone ie always produced, and prolonged heating of the esterification mixture results in the formation of some butadiene and tarry decom-
L. E. SCHNIEPP, J. W. D U N N I N G , A N D E. C . L A T H R O P NORTHERN REQIONAL RESEARCH LABORATORY. U. S. DEPARTMENT OF AQRICULTURE. PEORIA, ILL.
