BUTADIENE FROM ETHYL ALCOHOL

American two-step process, but studies were also made of the Russian one-step process, and the results of these studies are reported in this paper. GE...
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BUTADIENE FROM ETHYL ALCOHOL Catalysis in the One- and Two-step Processes B. B. CORSON, H. E. JONES, C. E. WELLING, J. A. HINCBLEY', AND E. E. STAHLY2

.

MeZZon I n s t i t u t e , Pittsburgh, P a .

N E X T E N D E D study

Materials. Feed for the one-step process was 92 weight

The wartime research in this country on the production of butadiene from ethyl alcohol was centered around the American two-step process, but exploratory studies were allocated to the possibly competitive Russian onestep process. The best catalysts for the one-step process were oxide mixtures of silicon-magnesium-tantalum and silicon-magnesium-chromium, and the best yield obtained in the laboratory (at 400 'to 425" C.) by the one-step process was 56% of the theoretical as compared with 64Yo produced by the two-step American process at the considerably lower temperature of 350" C. The same general areas in the periodic system were effective for both processes-mainly, the fourth and fifth groups, with less activity in the second and sixth groups-but the specific catalysts for the two processes were not interchangeable. The American two-step process comprised the dehydrogenation

cia1 Solvents Corporation). Feed for the two-step process was a mixture of 92y0 ethyl

of ethyl alcohol to acetaldehyde, followed by the catalysis of ethyl alcohol-acetaldehyde to butadiene. Intensive study of the second step indicated maximal cata-

e

of catalysts was made in the course of wartime research on the production of butadiene from ethyl alcohol. Interest was centered on the American two-step process, but studies were also made of the Russian one-step process, and the results of these studies are reported in this paper. GENERAL EXPERIMENTAL TECHNIQUE

?J

and in 10- to 20- and 25- to 50-gallon Nutsches; limited use was made of 5- and 12-inch basket centrifuges. Other major items were mechanical convection drying ovens, tube furnaces, catalyst pelleting machine, glass electrode pH meter, and electrolytic conductivity apparatus. Standard Commercial Catalyst. In order to have available a sufficient supply of a standard catalyst, 250 pounds of commercial catalyst were screened to obtain 4- t o 8-mesh material. and the latter (after mixing,'analYSiS, and catalytic evaluation) was used whenever a catalyst of known activity was required. Catalyst Testing. ONE-

acetaldehyde (Niacet Chemitheir highest activities at 350' C., whereas zirconia-silica processing 12 'tub& simul: cal Company). The and hafnia-silica combinations performed best at 300" C. taneously runs, used in the preparation The per pass yield of butadiene with the better catalysts sure, o.6 425' C., liquid atmospheric hourly space presof the catalysts were of reagent grade (in 80 far as Deswas 30 to 35% and the ultimate yield was 60 to 64%- The velocity (1.h.s.v.) 1. Catalyimmeenation steD in the DreDaration of silica-base catazate from' 50 ml.' of feed was silble).-with t h e notable-exseparated into gaseous and CePtihn of sodium Silicate lysts was equallykffectivewhen applied to dried, granular liquid components, and the which was Of grade silica gels and to slurries of hydrogels. (Karshaw N brand). Disbutadiene content of the tilled water (specific conducformer was determined to obtivity 3 to 8 X 10-6 mho) tain the per pass yield. Catswas used in all operations of catalyst preparation. Commercial lysts that showed a t least 15% per pass yield were prepared in larger amounts and tested in 8-hour runs (125 cc. of catalyst per catalyst (2% Taz06-98% SiOn) was obtained from the Rubber Reserve butadiene plants. tube) for both per pass and ultimate yields (atmospheric pressure, Catalyst Preparation. The general methods of gel precipita400' and/or 425" C., 0.4 and 0.6 1.h.s.v.). Two types of larger tion, gel coprecipitation, impregnation, and decomposition were testingequipment were used in the secondary screening: the modiemployed (see two-step process). fied Koppers unit (,$), the catalyzate being condensed in dry ice and Catalyst Identification and Analysis. The following code numsubsequently separated by distillation into butadiene, acetaldebers were employed: SB- and RR-series, catalysts prepared in hyde, and ethanol; and the precision scrubber unit (5) which quantities of a t least 800 cc. of 6- to 20-mesh granules (sufficient processed the catalyzate by extractive distillation to give an acetsupply for several larger scale laboratory tests); RRS-series, aldehyde-free gas (C, and lighter) and an aqueous solution concataIysts prepared in 125-cc. batches (6 to 20 mesh) for evaluataining unreacted ethyl alcohol-acetaldehyde feed and liquid tion in the multiple tester; RRX-series, numerous catalysts (only by-products. The catalyst temperatures re orted for the multiple a few of which wcre tested), prepared in the development of pretester were furnace-block temperatures' tiose reported for the parative methods. In so far as time permitted, all RR-series catalarger units were mid-bed temperatures, the inlet and exit temperalysts were analyzed for major components. Considerable effort tures being, respectively, about 5" and 10" C. lower. the diverwas expended in evaluating certain analytical procedures progence from the mid-bed temperature depended upon the feed rate. posed in the literature-e.g., the analytical separation of tantaPreliminary screening was made in the TWO-STEP PROCESS. um from zirconium and titanium. multiple tester with 2.75 to 1 mole ratio ethyl alcohol-acetaldeCatalyst Preparative Equipment. Glass, stoneware, and glasshyde feed a t 300 ', 350 O, and 400 C. (4-hour runs, atmospheric lined steel vessels up to 60-gallon capacity were employed. The pressure, 0.6 I.h.s.v., 20 cc. of catalyst per tube). Catalysts that glass-lined steel vessels were the most satisfactory. Agitashowed promise in the preliminary screening were tested in the tion was accomplished by 18-8 or Monel stirrers (sometimes larger equipment (125-cc. catalyst charge) in 8-hour runs a t 0.4 plastic-coated) operated by floor model drill presses or Model D 1.h.s.v. and 300', 350°, and 400' C. with 2.75 to 1 mole ratio Lightnin mixers. A great deal of filtration was involved, and it ethvl alcohol-acetsldehvde feed. Additional tests were usuallv

- -

L

-

1 Present

secondary screening were processed in four successive 12-hour periods in the modified Koppers unit; the catalyst was then reacti-

address, University of Chioago, Chioago, Ill.

* Present address, Commercial Solvents Corporation, Terre Haute, Ind. 359

INDUSTRIAL AND ENGINEERING CHEMISTRY

360

vated by air a t 400" C. and the test was continued for an additional 12 to 48 hours. Catalysts which showed a t least 25'% per pass and 60% ultimate molal yields of butadiene were scheduled for pilot plant testing (6-gallon catalyst charge in a 216 X 3 inch reactor). Only a few of the new catalysts were tested in the pilot plant because of the early conclusion of the research program. Calculation. Yields dnd efficiencies were calculatpd as follow: ONE-STEP PROCESS Per pass yield (mole %) =

moles of C4H6 produced X 200 moles of C Z H ~ O H fed

Ultimate yield (mole = moles of C4H6 produced X 200 moles of CzH50Hconsumed - moles of CH3CH0produced

Vol. 42, No. 2

350' C. mith a 2.75 to 1 mole ratio of ethyl alcohol-acetaldehyde feed, the average per pass yield was 36 mole % and the average ultimate yield was 64 mole %; the standard deviation of both was about 2% (4). This ultimate yield was in close agreement with that obtained commercially, but the laboratory per pass yield (obtained with fresh catalyst) was somewhat higher than that realized in the plants. Two catalysts showing maximal activity a t 300" C. (1.7% Ta20,-0.1% Zr02-98.2% Si02and 2.6% Zr02-97.4% SiO,, respectively) were tested in the Kobuta pilot plant. The results were identical, within the accuracy of the analytical methods, with those obtained in the laboratory and also in the commercial plants. Therefore, it is believed that the laboratory data on the two-step process presented in this paper are fairly indicative of expected plant performance.

TWO-STEP PROCESS

Per pass

moles of C4H6 produced X 200 %) = moles of (C2HsOH CH3CHO) fed

+

Ultimate yield (mole %) = moles of c4I& produced X 200 moles of CI3,CHO consumed moles of C2H,0H consumed 0.92

CATALYSIS IN THE ONE-STEP PROCESS

Although the main interest of the research program was in the American two-step process, a certain amount of time was allocated to thc possibly competitive Russian one-step process

2CzHSOH

+

+CHz=CHCH=CH*

+ 2HzQ + I&

Although the one-step process has been studied and operated in Russia for a t least 20 years (3, 21-19), no authentic and specific information on its operation and efficiency or on the comoosition of the catalvst was available to this countrr. Yields as high as 70% have been claimed ( I , 26,36,37). The Publicker moles of C4Hsproduced x 100 Acetaldehyde efficiency (mole %) = one-step process ( 3 , $8, 35, 4g), presumably similar to the moles of CH3CHO consumed Russian one-step process, was tested in this country on a pilot plant scale but was not put into commercial operation; the The formula for the ultimate yield by the one-step process takes yields were probably in the neighborhood of 50% (5). credit for acetaldehyde produced. The factor 0.92 in the ultiThe laboratory screening program revealed no one-step catalyst mate yield formula for the two-step process was used in conformcapable of better than a 56% yield (produced a t 400" to 425" C.) ance with plant practice, the ultimate yield of the dehydrogenacompared with the 64% yield given by the American two-step tion of ethyl alcohol being 92%. The ultimate butadiene yield process at the considerably lower temperature of 350' C. It is was therefore based on the over-all ethyl alcohol consumption. believed that the butadiene produced by the Russian one-step This factor was omitted in calculating the per pass yields, again process was less than 80% pure (36, 3'7) as compared with the to conform with plant practice. Product Analysis. The analytical methods, details of which are 98% or better purity of the American product, and it is also believed that the life (between regenerations) of the one-step catadiscussed elsewhere (4,SS), are outlined below. Catalyzate from lyst was about 12 hours (36, 8'7) as compared with 120 hours for the multiple tester was separated by extractive distillation into a the American butadiene catalyst. gas fraction containing C4 and lighter and an aqueous residue About 500 catalyst combinations were tested in a preliminary containing unreacted feed and liquid by-products. The gas fracscreening program in order to define the areas in the periodic systion was analyzed for butadiene by the Koppers-Hinckley tem which were effective for the one-step production of butadiene method (23,30); the aqueous residue was discarded, being too from ethyl alcohol. Some of the more promising catalysts were small for significant yield data. Catalyzate from the larger tested further, but no life tests were made. The same general scrubber unit was separated as above, and the gas was analj-zed areas in the periodic table were effective for both the one-step and for butadiene and the aqueous residue for acetaldehyde (by hythe two-step processes, mainly the fourth and fifth groups, with droxylamine) and ethyl alcohol (by phthalic anhydride). less activity in the second and sixth groups; specific catalysts for Catalyzate from the Koppers unit was condensed a t -78" C. the two processes were not interchangeable. and distilled into three fractions, which were analyzed for butadiDiscussion of Results. After an evploratory temperature study ene, acetaldehyde, and ethanol, respectively. Preliminary Standardization. Analytical methods for ethyl it was decided to operate the multiple tester a t 425" C. for the alcohol, acetaldehyde, butadiene, and certain by-products, inpreliminary screening tests and subsequently to test the more volving chemical, physical, and optical procedures, were reh e d to the point where yield TABLEI. PERFORMANCE DATAFOR BESTONE-STEP CATALYSTS values in the range of greatest C4H6produced loo Ethyl alchol efficiency (mole %) = moles of CzHsOHconsumed Of

interest (25 to 35% per pass and 60 to 70% ultimate) were accurate to about 1% (4). After brief variable studies

on the effect of catalyst mesh

size and dimensions of catalyst bed, 16 identical runs were made with commercial catalyst to establish the duplicability of the combined operation of activity testing and product analysis. At 0.4 1.h.s.v. and

RR-C2-26=

RR-C1-12

RR-C1-04b

Catalyst

RR-C2-6" 60% M e 0 31% Si02

RR-C1-68 1% C u 0 2% Tat06 07% Si02

RRS-Cl7-26c 100% h'IgC0s

I n one-step process ( 0 . 4 l.h.s.v., 92 wt. ethyl alcohol feed, 8-hour runs) 400 425 420 420 425 410 426 ~ ~ ~ ~ ~ ~ $ $ & o $ ' 38 ~ r ~ s 39 34 39d 18 9 25 Ultimate yield, % CaHe 56 49 50 51 27 36 30

425 12 30

I n two-step process (0.4 l.h.s.v., 2.75/1 ethyl alcohol-acetaldehyde- feed, 8-hour runs) Temperature, 0 C . 350 400 350 400 350 400 350 400 350 Per P&SSyield. % CaHe 16 23 16 27 1 10 17 25 40 Ultimate yield, 7% C4HO 32 33 18 30 37 33 40 60

400 12 35

,.

a Saukiewica (28, 56). b Magnesol ha3e. magneslum oxide. d Reaenerated catalvst.

C

Undetermined amount of oxide present; Ipatieff (7)disolosed use of

GIVINGAT LEAST10% YIELDOF BUTATABLE 11. CATALYSTS DIENE PER PASS IN ONE-STEPPROCESS Catalyst Composition 59% MgO-2% Crs01-39% SiOz 60% Mg0-2% Taz06-38% SiOz 95% MgCOa-5% Si02 1.1% CuO on 2% Taz06-98% SiOn 9 . 5 , ZrOe-90.5% Sioq 50JMgCOa-50% MgSiOa 9 8 9 MgCOa-2'7 Si02 10% Zn0-90% &oz 2% Taz06-45% Mg0-53% si02 21% MgO-2% TazOe-77% SiOz 277 P b 0 - 9 8 7 AlzOa 1 9 Ti0s-9%oZrOz-90% AleOa 57% SbzOs-38% AlzOa-5% $101 80% M COa 20% SiOz 277 Taz8s-98% SiOz 7 0 9 Mg0-30% SiO? 90% MgCOs-10% SiOz 4.6% VZOK-95.477.Si02 95% MgCOa-59' 8 1 0 2 30% SbzOs-70 %'AlzOa 46% MgCOa-54% SiOz 75% SiOa-24.7% ZrO?-0.3% SbeOs 1 1'7 TazOs-98.9% Sloe 95%oMgCOs-5% SiOe MgCOa MgCOa-57 Si02 MgCOa-1% SiOn 5 0 7 M 0-50% SiOe 3 8 d Vz%s-127 AgNOa-50% SiOn5 2% TazOs-989 Florisil 1% TiOz-9% !i?rOz-gO% AhOa

:ig

T!Oz TlOz TiOz

80% MgCOz-20% S10z 10% CdO-90% S i 0 2

30% Pb0-70% Sloe a Si02 was Bantooel (low density gel).

D

Butadiene per Paas Yield, % 39 34 28 25 23 21 20 20 20 18 18 17 17 17 16 15 15

Code No. RR-C2-26 RR-C1-12 RRS-C20-32 RR-C1-68 RR-C2-8 RRS-(214-26 RRS-(314-24 RRS-(29-16 RR-C16-4 RR-C1-94 RRS-C19-72 RRS-C7-84B RR9-C19-62 RRS-C7-52 RR-C1-4 RRS-C 11-24 RRS-C7-80 RR-C2-20 RRS-C7-82 RRS-C9-92 RRS-C7-44 RRS-C13-28 RR-'21-86 RR-17-30 RRS-(217-26 RR-(214-22 RRS-C17-24 RRS-Cll-26 RRS-C9-66 RR-C1-96 RRS-C7-84A RRS-C7-24B RRS-C7-48 RRS-C7-32 RRS-C20-34 RRS-'29-38 RRS-C19-70

14

14 14 14 13 13 13 12 11

11

11 11 10 10 10 10 10 10 10 10

promising catalysts in larger equipment at several temperatures and feed rates. At 425" C. a surprisingly large number of contact materials produced small amounts of butadiene, although only a few gave commercially significant yields. The best one-step catalysts gave per pass yields ranging from 9 to 39% and ultimate yields ranging from 27 to 56%. According to the data presented in Table I, one-step catalysts are not suitable for the two-step process. The magnesia-chromic-silica catalyst (RR-C2-26) showed a higher ultimate yield a t 400' C. than at 425' C. although the per pass yields were essentially the same at the two temperatures; once-regenerated magnesia-tantala-silica (RR(21-12) gave a higher per pass yield than fresh catalyst. Table I1 lists one-step catalysts which displayed per pass yields of 10% and better on the multiple tester; Tables I11 and IV record one-step catalysts which gave per pass yields of 7 to 10% and less than 7%, respectively, also on the multiple tester (at 425' C. and 0.6 1.h.s.v. in all cases). Several oxides and salts (lead oxide, antimony trioxide, aluminum oxide, vanadium trioxide and pentoxide, chromium trioxide, titanium dioxide, magnesium carbonate, and silver nitrate, usually mounted on silica) showed appreciable activity in the one-step process, but were ineffective in the two-step process. Mechanism of One-Step Process. A study of the mechanism (8) of the second step of the two-step process-the reaction of acetaldehyde with ethyl alcohol-revealed that crotonaldehyde was an important intermediate (Equations 2 and 3), as indicated by Quattlebaum, Toussaint, and Dunn ( 2 7 ) .

+

showed that the addition of acetaldehyde increased the yield of their one-step process, and i t is assumed that recovered acetaldehyde was recycled in commercial operation. Lebedev and coworkers (11-19)assumed, without experimental evidence, that the mechanism of the one-step process involved two biradicals [-CHZCHz- and --CH2CH( OH)-], and they emphasized the value of these biradicals in explaining the formation of numerous by-products, which, as has been clearly pointed out (27), can be explained equally well without free radicals. Assuming the important reactants of the one-step process to be acetaldehyde and ethyl alcohol, i t would seem logical to produce acetaldehyde under the proper dehydrogenating conditions, and then react i t with ethyl alcohol, also under optimal conditions. Such is the American two-step process. If the Russian one-step process is to be competitive with the two-step process, a compromise of catalysts and conditions must be found for widely diverse reactions. Previously Disclosed Catalysts. Lebedev and associates (11-19) reported that the one-step process required a "dehydration-dehydrogenation" catalyst. This self-evident conclusion merely takes cognizance of the obvious fact that the elimination of water and hydrogen is involved in the over-all reaction (Equation 5 ) . I n view of the thousands of possible permutations, this disclosure has little teaching value, except in an elementary way, for the selection of an effective catalyst. Of the 500 one-step catalyst combinations (all of which can be considered as dehydration-dehydrogenation catalysts) evaluated in exploratory manner in the present research program, none equaled in performance that of the better catalyst combinations of the two-step process. Moreover, none of the few one-step catalysts described in the literature with any degree of clarity was more than mediocre in performance (Table V). These disclosed catalysts, although poor in the two-step process, were better in the two-step process than in the one-step process for which they were intended. Conclusions on One-Step Process. The data presented give numerous leads for future exploration in the event that ethyl alcohol should again bePome important as source material for butadiene-a real possibility with the advent of cheap synthetic ethyl alcohol. A multistep process would seem more logical than a single-step process, inasmuch as the various intermediate reactions required different conditions and catalysts for maximal realization. The logical research approach would seem to be the establishment of optimal conditions and catalysts for the various reactions involved. CATALYSlS IN THE TWO-STEP PROCESS

The American ethyl alcohol-butadiene process which produced 60% of the butadiene required for the war emergency synthetic rubber program (4,20, 24) comprised two steps: dehydrogenation of ethyl alcohol to acetaldehyde, and catalysis of acetaldehyde-ethyl alcohol to butadiene. This process, based

TABLE 111. CATALYSTS GIVING7 TO 10% YIELDOF BUTADIENE PER PASS IN ONE-STEPPROCESS Butadiene

Catalyst Composition

CzH5OH + CHsCHO Hz (1) BCHSCHO +CHsCH=CIICHO HZO (2) CH&H=CHCHO CzHsOH --+ CH2=CHCH=CH2 HzO CH8CHO (3)

+

+

+

+ CzH5OH +CHz=CHCH=CHz + 2Hz0 2CzHsOH --+ CHz=CHCH=CHZ + 2Hz0 + Hz CH3CHO

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INDUSTRIAL AND ENGINEERING CHEMISTRY

February 1950

+

(4) (5)

It is logical to assume, in the absence of proof to the contrary, that the one-step process (Equation 5) involves the same reaction sequence. I n fact, the Russian investigators (11-19,56, 37)

a Magnesol. b Ultimrtte yield 36%.

Code No. RR-(21-44 RR-C17-28 RR-C2-6 RR-C1-72 RR-C1-14 RR-C5-24 RRS-C6-32 RRS-C13-30 RRS-C13-32 RRS-C13-38 RRS-'219-12 RRS-C13-4 RRS-C13-6 RRS-C9-2OA RRS-Cll-42

E;l,qaE 8 9 9b 7 8 9 7 8

8 8

8 8 8 9 8

INDUSTRIAL AND ENGINEERING CHEMISTRY

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Vol. 42, No. 2

on the work of Ostromislensky (66), was developed by the Carhide and RRS Carbon Chemicals Corporation (27, RRS Code Code 39, 4U) and operated by that organiComposition No. Composition NO 1% hgC1-99% SiOn zation and Koppers Company, Iiic. CD-8 c24-10 2% AgCl-98% Si02 c9.10 C24-4 The ultimate yield, based on ethyl 1% AgzO-99% SiOz C9-12 C24-6 50% AgnSeOa-50% SiOa C22-16 C24-8 alcohol, was about 63% in favorable 42% AgzSeO3-4247, SiOz-16% CUO C7-96 commercial operation. The t,hree comC22-18 C14-26B C17-8 ClD-36 mercial plants (located a t Institute, C17-10 C19-90 Cll-22 C19-92 W. Va., Kobuta, Pa., and Louisville, C11-58 C19-94 Ky.) operated a t 2007, of rated capacCll-60 C10-96 Cll-64 Cl9-98 ity to meet the early emergency reC13-20 c14-2 C13-42 C7-42 quirements for synthetic rubber. C13-86 C20-14 In July 1944 research JTas initiated C13-92 C20-16 (213-94 C14-2 at the Mellon Institute to investigate C13-96 c12-12 C13-98 C24-32 the variables of the second step of Cll-90 (214-12 the above process. Commercially this Cll-92 C13-64 C13-66 C13-52 second step comprised the processing C13-64 (313-36 C9-46 ‘213-56 of a mixture of approximately 69 C9-48 CR-30 weight % ethanyl alcohol, 24 weight C6-40 c19-58 C6-52 C19-60 % acetaldehyde, and 7 weight % mater Cll-32 C22-10 Cll-34 c22-12 over 2% Ta206-98% SiOa a t 326” to C19-74 (29-28 350’ C., 0.4 t o 0.6 liquid hourly space C19-76 C9-34 C9-82 C9-42 velocity, and essentialljp at,mospheric C9-81 C9-44 C19-78 C9-86 pressure, the catalyst, being regencrc19-80 C9-88 C9-90 ated by “burii-offJ’ every 4 or 5 days c19-82 (319-54 C19-84 (4).The immediate objective of this C19-56 C19-86 c19-88 investigation was to discover changes C7-28 C9-40 in catalyst composition or preparation, C13-58 C19-2 C13-60 C19-4 or changes in the operating conditions C13-62 C6-38 C13-70 (311-18 of the catalysis, which could be exC14-16 C13-34 CrtOs C1’-18 ploited in the already built and operatC13-10 C14-20 C 19-12 ing commercial plants to give a higher Cll-20 C13-14 C13-68 C24-21 yield or a greater throughput. The C6-50 Cll-94 C24-16 maximal temperature studied in this Cll-96 C24-18 C13-46 research program was set a t 400” C. C24-20 C13-48 c24-22 C13-50 by the construction of t,he commercial C19-10 C13-88 plants. Temperatures below 300 C. c19-14 C13-90 Cl9-16 were investigated when warranted by C22-28 Cl9-18 C6-48 Cll-88 the trend of the temperature effect. C6-72 (320-38 03-70 The several approaches toward yield C20-40 C7-56 C22-26 improvement were: ( a ) utilization of C11-44 C13-76 Cll-50 C22-20 certain by-products-e.g., ethyl acetate Cll-74 c22-22 Cll-76 C9-62 (39, $4) and crotyl alcohol (8); ( b ) C19-28 C9-64 operation by the one-step process; ( e ) C7-46 Ci-58 C7-34 C20-18 modification of the operation of the c11-2 c20-20 c11-8 C20-22 two-step process (4, IO); and ( d ) modiCll-10 C20-24 fication or replacement of the comCll-12 C13-26 (311-14 C13-24 mercially employed catalyst. Because Cll-36 C22-14 Cll-38 C9-24 of the early termination of the research Cll-66 C9-26 program a t the cessation of hostilities, Cll-72 C14-8 Cl9-20 Cll-66 time was not available for the coinc19-22 Cll-68 C19-24 plete scanning of the periodic table Cll-70 C19-26 C13-72 or for the testing of numerous promiac11-4 C6-34 Si01 C14-10 ing catalysts on pilot plant scale. C11-6 C6-60 C22-30 C6-62 In the course of this work 612 cataC22-32 C6-64 lysts were prepared and evaluated; C22-34 (211-28 C22-36 Cll-30 nineteen gave per pass and ultimate C6-36 C7-38C C7-32 Cll-82 yields of the same order of magnitude C17-18 Cll-84 as the commercially employed catalyst C7-46 C19-38 C7-48 C19-40 (48- to 96-hour tests). These catalysts C13-82 C19-48 were ready for pilot plant evaluation. a CC indicates commercial catalyst ( 2 % TaaO6-98% Sioz). Fifteen additional cat’alysts were found to be active in the preliminary screening but were not evaluated by the secondary screenine. Fortv elements were inzirconia-silica, thoria-zirconia-silica, zirconia-silica (good) ; magnevalved in the investigation. The best catalysts were the following combinations: tantala-silica, hafnia-silica (very good); copper sium carbonate-silica, magnesia-silica, nickel sulfide-silica, and oxide-tantala-silica, columbium oxide-zirconia-silica, titaniauranium octoxide-silica (fair). Combinations of silica wit,h oxides

-

YIELDOF BUTADIENE PER PASSIN ONE-STEPPROCESS RR

RRS

Coda No.

Composition

Composition

C13-84 C7-76 C17-12 C13-78 (213-80 Cll-48 Cll-54 C9-60 C24-30 C6-54 C6-68 C6-58 c9-18 C9-22 C11-16 C9-30 C9-32 C17-2 C17-4 (217-6 C6-28 C6-42 c7-54 C9-50 c9-54 C9-56 C9-58 C11-40 Cll-46 Cll-52 Cll-78 Cll-80 C13-32 C7-36 C9-76 C9-78 C9-80 C19-42 C19-44 C19-46 C14-14

Ziikite

RR Code No. C5-10 (35-84 C5-36 C 1-46 2-88C (22-12 C2-22A C2-22B C5-16 C2-4 C2-16 C2-18 C5-32 C7-2 C1-32 c7-4 C9-6 c9-4 C9-2 C1-42 c2-4: 2-80 C1-56 C7-30 C1-70 C5-6 C2-14 c1-22 C7-66 C16.50 C1-26 c5-4 C1-58 C16-38 C16-58 C16-70 C1-54 C1-36 C1-52 c1-98' C1-60 C16-80 c7-74 C16-40 C1-4B C1-40 C16-42 C1-8 (21-34 c5-54

AhOs. BzPa 2% AlFa-98% Si02 10% AlFa-90% Si02 AlFa AlaOab A1 Oa gel AlfOa gel

a

b Temperature 450°

363

INDUSTRIAL AND ENGINEERING CHEMISTRY

February 1950

C.

C

SB Code No.

of certain transitional elements of Groups IV and V were in general the most active catalysts, Six elements whose oxides (in combination with silica or alumina) showed less activity were antimony,

Code No. C16-78 C1-4 C16-56 c1-2 C16-60 C1-38 c1-90 C16-76 1-8 C16-24 C5-52 C16-22 (21-82 C16-82 C7-40 C16-86 C16-88 C7-68 C1-62 C1-64 C1-66 C16-30 C16-32 C16-34 C7-90 C7-92 C1-84 c1-50 C1-16 C16-2 C1-92 C16-6 C16-10 c1R-36 C16-64 C16-28 C7-64 C16-44 C16-12 C16-66 C16-46 C16-68 C1R-48 C16-14 C5-12 C16-82 C16-84 c5-2 c5-38 c5-20 C5-40 C5-42 C5-46 c5-48 c5-44 (25-18 U7-50 C20-2 C20-6 C1-24 c5-8 C5-30 C16-52 C16-54 C20-4 c20-8 X-C3-10 C5-28 c1-88 c1-100 (2.5-22 C16-74 C1-30 C7-70 C16-72 C2-24B C17-20A Cl6-26 c2-10 C2-42 Cl6-%3 C2-86 C2-44 C2-48 C2-46 C7-72 c2-2 C5-50 C1-6 C5-14 c2-50 C17-16

cadmium, chromium, tin, titanium, and zinc. Any future study of the catalysis of ethyl alcohol-acetaldehyde mixtures to produce butadiene should pay especial attention to silica gel slurries (as distinguished from predried gels) impregnated with hafnia, cupric oxidetantala, zirconia, and zirconiatantala, and to ferric chloride-set silica gel impregnated with zirconia, tantala, and hafnia. There are indications that the production of butadiene from ethyl alcohol-acetaldehyde proceeds by a two-step mechanism (8, 9, 27)-condensation of acetaldehyde to crotonaldehyde, followed by deoxygenation of crotonaldehyde by ethyl alcohol. The two-step mechanism probably also operates in the one-step process for the manufacture of butadiene from ethyl alcohol (9, $6,28, 35, 41).

PCHDCHO

--+

CI-I&H=CHCHO

+ 1320

(6)

Evidence has been presented (8) that the silica component of the catalyst catalyzes the condensation of acetaldehyde, whereas the tantala component catalyzes the deoxygenation reaction. This hypothesis was a useful guide in the search for active catalyst combinations. Catalyst Preparation. As well recognized in catalysis, the method of preparing a catalyst is often as important as its chemical composition. The variables of gel preparation and impregnation and of the dehydration of gels and catalysts were studied in some detail. In general, catalysts based on silica gels that had been precipitated at low acidities were active a t lower temperatures than catalysts based on silica gels that had been precipitated a t higher acidities. The lower temperature of optimal catalytic operation was usually well defined-for example, a catalyst which was active a t 300" C. would have negligible activity a t 285" C. On the other hand, the upper temperature of optimal catalytic operation was less definite. A considerable study was made of the preparative variables of catalysts containing tantala, zirconia, and silica, which were the most active components. The major preparative variables were: history of the silica carrier prior to impregnation, state of dehydration of silica at impregnation, method of impregnation,

INDUSTRIAL AND ENGINEERING CHEMISTRY

364

Vol. 42, No. 2

of the pilling operations were made with hydrogenated peanut oil which was subsequently 25% znoa RRS-Cig-14a RRS-C11-54b RR-CR-30b RR-Cl-72b RRS-Cl9-44O Catalyst removed by benzene extrac75% AlzOa 8% ZnO 10% UOa 2% YO3 9 % MnOz 2% ZrOz 90% A1203 90% pumice 98% Si02 91% SiOz 1 0 7 ThOn tion. Several catalysts (some 2% CUO 88g Si02 of which were fairly active) I n one-step process ( 0 . 4 l.li.a.v., 92 weight % ethyl alcohol feed, 8-hour runs) were very simply compounded Temperature, C. 425 425 425 426 425 426 by wet grinding in a porcelain Per pass yield % C4He 10 1 1 0 7 1 Vltimate yield, % CaHe 15 .. .. 0 12 .. ball mill. I n two-step process (0.4 l.h.s.v., 2 . 7 5 / 1 ethyl alcohol-acetaldehvde feed, 8-hour runs) SILICA GEL SUPPORT. BeTemperature C. 375 350 cause silica was employed as Per pass yielh % ~ 4 ~ s 14 5 carrier in the commercial Ultimate yield, % C ~ H S 19 15 catalyst, and because its 5 Lebedev et al. (11-19). Spence, Butterbaugh, and Kundinger (51). b Talalay el al. ( 86, 9 7 ) . superiority to various other porous supports was established early in the program, a considerable study was devoted to silica. Still another treatment of impregnated gel, amount of promoter relative to reason for emphasis on silica was its ability to catalyze silica, and impurities in the finished catalyst. Certain catalyst the condensation of acetaldehyde to crotonaldehyde, which requisites were: porosity; thermal stability at the temperatures reaction was the first step in the hypothesized two-step of catalysis and reactivation; inertness under operating condimechanism (8-20, 27, 28) responsible for the production of tions to certain organic compounds, steam, and oxygen-containbutadiene. ing "burn-off" gas; physical form of sufficient strength to permit It was realized that certain fundamental properties of silica testing by fixed bed operation; and carefully controlled preparagel-e.g., surface area, pore size, and pore distribution-depend tion to permit reproducibility. upon numerous preparative variables; Tamele, Byck, Ryland, PRECIPITATION AND WASHING. Catalysts were prepared and Vinograd (38) recognize 25 variables. The present authors by precipitating single insoluble salts or hydrous oxides, comade no attempt to evaluate all these possibilities in this research precipitating two or more insoluble materials, and precipitating program, whose objective was the quick commercial exploitation one or more insoluble materials in the presence of another inof discoveries for the war emergency. An attempt was made to soluble material such as silica hydrogel. (Catalysts were also standardize the conditions of gelation, impregnation, and drying prepared by physical admixture of gels.) Suitable precipitation conditions were employed to produce amorphous, nearly colloidal precipitates, and the reactants were chosen to give soluble and/or TABLE VI. BESTCATALYSTS volatile salts as by-products of the metathetical reactions. Wet IN TWO-STEPPROCESS (Large unit, 2.75 t o 1 mole feed ratio, 0.4 1.h.s.v.) precipitates were washed by slurrying with 5 to 20 volumes of T ~ ~ Mole ~ , T,oYield water for several hours followed by filtration. The extent to Catalyst Composition Code No. Hours C. Per pass Ultimate which the precipitates were freed from adsorbed soluble ions was SB-3-24 8 fi0 1 . 0 % TazOr-99% Si02 350 27 followed by the conductivity of successive filtrates; washing was 36 350 1.1% TanOa-98.9% si02 RR-Cl-64 36 to 26 62 to 49 8a 350 44 1 . 2 % TazOs-98.8% Si02 RR-C1-36 63 continued until the conductivity fell below 10-4 mho or until 48 350 1 . 2 % Taz06-98.8% #ion RR-(21-52 34 to 26 68 to 56 it approached a limiting value fixed by the solubility of the 1 . 3 % TanOa-98.7% SiOz RR-'21-60 8a 63 350 35 1 . 5 % T a n O ~ 9 8 . 5 %SiOz RR-C1G-40 65 8 33 3.50 precipitate. 60 1 . 7 % Tan06-98.370 Si02 RR-C1-8 48 25 300 Same catalyst 85 59 350 42 Various conventional procedures were emIMPREGNATION. 48 300 26 GO RR-C1-78 8 ployed. One method was to soak fairly strong chunks of carrier350 32 67 RR-C1G-16 48 26 GO 300 e.g., silica hydrogel containing 90 to 95Oj, of water-in the 8 350 40 63 48 63 350 40 to 26 impregnating solution, assuming that sufficient time of diffusion RR-C5-54 62 48 350 34 RR-(31-64 would give homogeneous impregnation. The procedure usually 36 8 GO 350 employed with a hydrogel which had been broken down meRR-C1-68 12 GO 350 40 chanically by slurry-washing was to disperse the slurry in the 48 64 30 350 RR-C16-56 aqueous impregnant and dry the total mixture. I n order to avoid 48 29 to 24 62 to 56 300 RR-C1-2 61 48 24 300 inhomogeneous impregnation due to sedimentation, the volume RR-C1-38 69 8 34 400 RR-1-8 65 8a 31 350 of aqueous impregnant was such as to yield a heavy slurry, or the RR-C5-62 64 48 38 350 RR-C1-82 8 GO mixture was stirred during the early stages of drying. The 350 39 RR-C17-36 48 22 63 to 57 300 catalysts were finally dried in tube furnaces in controlled atmosRR-'216-28 64 48 29 300 pheres in order t o take up shrinkage so that the catalyst volume 48 63 300 24 would remain constant during activity testing, expel adsorbed RR-C16-48 64 48 29 350 water, evaporate volatile salts not removed by washing, and 63 48 380 28 effect desired oxidation or reduction. The usual schedule for RR-(21-48 8 62 350 38 high temperature drying was to raise the temperature from that RR-C1-50 60 to 58 350 48 32 of the room to 300" or 350" C. during 4 to 6 hours and to main12 65 350 29 tain the maximal temperature for 1 or more hours. RR-C1-14 48 350 31 60 SCREENING,PILLING,A N D BALL MILLIKG. The granular 8 60 RR-C7-90 350 37 catalysts were usually sized to 6 to 20 mesh; the apparent denRR-C16-64 8 350 18 62 sity was obtained by weighing a standard volume of well-packed 8 300 RR-C16-74 16 GO 6- t o 20-mesh material. Some catalysts were produced as fine 8 RR-C2-24B 300 33 61 powders which, of course, could not be evaluated catalytically 300 30 58 RR-C17-20.4 48 8 64 RR-(32-24 300 30 by fixed bed technique; these were pelleted ( l / * X inch pills) 300 60 48 20 60 RR-C2-10 8 300 in a Stokes pill machine (Model E). Graphite up to 4% by 27 24 RR-C5-56 64 29 300 weight was initially used as die lubricant, but because its suba 2 t o 1 feed ratio. sequent removal involved considerable time-temperature exb Activity could not be duplicated for confirmation. posure with possible detriment to catalytic activity, the majority TABLE v.

PERFORX4NCE D.4TA FOR

CERTAIN ONE-STEP CATALYSTS DISCLOSED BY LEBEDEV AXD OTHERS

O

C

February 1950

INDUSTRIAL AND ENGINEERING CHEMISTRY TABLE VII.

Catalyst Composition 1 . 0 % Kz0-99.0% Alios 2.0y0 LizO-98.0% Si02

15.1% Be0-84.9% Si02 MgCOa 14 7 7 Mg0-85 3% Si02 21'0.3 Mg0-79'0% Si02 30% i%gO-7O%'SiOz 49.3% Mg0-0.3% MgClz-50.4% Sloe 60% MgCOs-40% A h 0 1 90% MgCOl-10% Si02 99% M g C O r l % fhOe 60% Mg0-40% AlzOa 10% Zn0-90% Si02 2 7 2110418%AlzOs 25% Zn0-76% Ale01 10% Cd0-90% Si02 20% CdO-80% AlzOi

CATALYST ACTIVITY ON BASISOF PERIODIC SYSTEM(TWO-STEPPROCESS)

Code No. Group I RR-C2-14 RRS-C7-58

(8-hour runs: Mole % Per pas0 T, a C

0.4 1.h.a.v.; 2.75 to 1 mole feed ratio) Yield Ultimate Catalyst Composition

350 350

14 4

17 7

Group I1 RR-C2-16 RRS-C17-26 SB-3-27B SB-3-SA RRS-Cll-28

350 400 350 375 350

7 12 21 23 22

29 45 54 54 40

SB-3-25 RRS-'219-52 RR-C17-28 RRR-(217-24 RRS-C19-48 RRS-C9-18 RRR-C17-2 St)-2-50 RRS-C9-38 RRS-(319-6

350 400 400 400 400 350 400 360 350 350

25

50 30 49 40 25 20 20

; ; 19 6 8 14 5 10

9

6

25 15

Group 111 AlzOa AlFa Fuller'R earth 20% AIP04-80% AlnOs 16% Alz(SOSs-84% € 3 0 2 2% CezOs-98% SiOn 2.3% NdrOa-97.7% Si01

RR-C2-12 SA-2-56 PB-2-81 SH-2-52 SB-2-40

350 375 350 350 350

21 14

6 12

15

29 47 28 10 25

Rare Earths RR-C5-32 RR-(25-6

350 350

12 13

27 27

Group IV Si02 TiOz ZrOz Sn02 2 . 3 % Zr02-97.77 SiOn 2% HKh-98% si& 1% T10z-99C7, S1Oz 2% SnOz-98% SiOn 27" ZrOz-5% ThOz-93% Si02

*.

365

RR-C-16-62 RRS-C7-24C RR-C1-6 RR-C5-2 RR-C2-24B RR-C6-56 RR-C5-20 RRS-C24-12

350 300 400 350 300 300 350 400

4 8 8 1 33 31 18 9

32 20 9 2 61 64 52 20

RRS-'219-42

350

32

55

TazOs 2 3 V TazOs-97.7% 1:2% TazOa-98.8% 2.1 % TazOs-97.9% 1 . 0 % TazOs-99.0% 2.07 2.38 5.7% 1.04 4.6%

SiOz

SiOa

SjOz SiOz

Code No. Group V RRS-C6-70 RR-C1-38 RR-C1-52 RR-Cl-2 SB-3-24

T a z 0 6 - l . l % Cu0-96.9% Si02 RR-C1-68 TazOa-0.2% ZrOe-97.5% SiOn RR-(216-28 Taz06-94.3% AhOs RR-C16-50 Cbz06-99.0% sloz RR-(27-2 RR-C2-20 VzOa-95.4% SiOe

5% VnOs-95% SiOz 5% VZ06-95% AbOs 30% ShzOs-70'7 AlzOa 57% SbnOa38% &01-5% CrzOa WOa 0 3% WOa-99.7Y

--

si02

SiOn

10% W01-90% AfzOa Same catalyst 12'7 CraO1-88% Ale08 40% CrrOa-60% AlzOs 5% CnOs-8% Ms0-87% Si02 2 . 0 % MoOs-98.0% 8iOz 2'7 Ud38-98% sioz 5 9 UaOs-8'7 Mg0-87% SiOn 1% U~0a-2% TazOs-97% Si09 10% u@8-90% Floridin

SB 2 49 SB-2-53 RRS-(29-92 RRS-C19-62 Group VI RRS-C13-44 RR-C5-8 RR-C1-24 SB-2-8 SB-2-20 RRS-C13-8 RR-C7-30 RRS-C12-12 RR-'25-30 RR-CIB-54 RR-C16-100 SB-2-65

T,

O

C.

Mole % Yield Per Ultipass mate

300 400 350 300 350

24 34 34 28 27

45 69 68 66 60

350 300 350 350 300

40 32 18 15 4

60 62 30 39 16

350 300-400 400 400

0 14

6

20

10 0 30 35

400 350 400 300 250 425 400 400 350 3.50 350 350 375

15 2 6 11 6 15 12 20 2 17 20 31 18

40 3

9

15 40 21 20 38 5

22 34 55 30

9 . 2 7 MnO?-90.8% Si02 Mn C?ln-Flon t e AlFa 10% AlF8-90% SiOe

Group VI1 RR-C1-72 SB-3-22 RR-Cl-46 RR-C5-36

400 3.50 350 350

23 10 13 4

37 20 40 5

15% NiS-85% SiOe 16% COO-857 Altos 15V FezOs-8581 Si01 1 5 8 FezOs-858 AlzO

Group VI11 RRB-C13.56 RRS-(211-96 RRS-020-40 RRS-Cll-88

350 350 350 350

18

30

(especially during the low temperature period) to ensure reproducibility. Silica gel, itself, has some catalytic ability for the production of butadiene from ethyl alcohol-acetaldehyde (ca. 4% per pass, 23% ultimate) which was thought to be possibly due to trace impurities. However, a relatively very pure sample (ea. 0.004% of nonvolatile residue after hydrofluoric-sulfuric acid treatment) showed approximately the same catalytic activity as the less pure silica (ea. 0.2Oj, residue) otherwise employed. The silica carrier used in the majority of the catalysts was derived from two standardized hydrogels (A and B) which were prepared from time to time in rather large amounts and stored under water; it was established that this storage did not affect the character of the gels. SILICAHYDROGEL A. Briefly, the pre aration consisted in acidifying to p H 4.5 about 4800 ml. of N t r a n d sodium silicate (9.2% sodium oxide, 28.6% silica, specific gravity 1.38, titratable alkalinity 3.94 N ) , dissolved in 4 gallons of water, with 1710 ml. of concentrated hydrochloric acid (specific gravity 1.19) dissolved in 4 gallons of water. The diluted acid was added rapidly to the diluted sodium silicate with violent agitation ( H 2 to 3),and the pH was subsequently adjusted to p H 4.5 by afding about 60 ml. of undiluted silicate. Gelation took place in about 3 minutes a t pH 4.5. After standing for 1 hour the gel was slurried by stirring with 30 gallons of water for 1 hour and subsequently filtered. The resulting Nutsch filter cake was likewise slurried in 30,gallons of water for 1 hour. This washing process was repeated 13 times, 250 grams of ammonium chloride being dissolved in the wash waters of the second to sixth filter cakes. The specific conductance mho. The filter cake conof the thirteenth filtrate was 9 X tained about 6.4% of silica; residue from the silica was about of the 6- to 20-mesh gel (dried SILICAHYDROGEL B. The reparation consisted essentially in acidifying 3205 ml. of N bran$ sodium silicate (diluted with an

1 6 2

..

35 20

equal volume of water) with 2410 ml. of concentrated hydrochloric acid (diluted with 3800 ml. of water). This amount of acid was 2.15 times as much as that employed in the preparation of hydrogel A. The diluted silicate was slowly added to the diluted acid with violent agitation and the mixture was ladled into enameled pans to gel. The time of gelation was about 30 minutes. The gel was cut into chunks which were submerged in water (2 volumes of water per volume of gel) and the water was changed daily (for 18 days) until the specific conductivity of the wash water was 9 X 10-5 mho. About 120 gallons of water were required. Hydrogel B filter cake contained about 10.8% of silica and the average amount of nonvolatile residue from the silica was 0.08% (range 0,009 t? 0.15%); the average density of the 6- to 20-mesh granules (dried a t 110' C.) was about 0.7. OTHERSUPPORTS.Numerous commercial activated aluminas were tested as supports and as catalysts, and a wide variety of 2- and 3-component alumina catalysts were prepared by coprecipitation. Other supports were titania, chromia, and zirconia gels, pumice, silicon carbide, and magnesia. Titania hydrogels were produced by mixing titanium tetrachloride with aqueous ammonium carbonate a t several temperatures and carbonate concentrations. Gelatinous precipitates of chromium hydroxide were obtained by reaction of hot aqueous chromic nitrate with aqueous ammonia. The zirconia gel was obtained by the reaction of aqueous ammonia on zirconyl nitrate solution. The magnesia base was obtained by the precipitation of magnesium hydroxide by organic amines such as diethylamine and morpholine. Catalytic Activity per Periodic Group. In general, catalytic activity was maximal in the oxides of the elements of Groups I1 to VI, and more specifically in the oxides of the elements included in a diagonal band drawn through magnesium to uranium on the usual periodic chart. This band includes scandium,

366

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Vol. 42, No. 2

367

3

..

se

368

INDUSTRIAL AND ENGINEERING CHEMISTRY

N

n a P

%

Vol. 42, No. 2 which was not available for test. Table VI lists the best catalysts (mainly Groups I V and Ir)~ Table VI1 presents data for the best catalysts from each periodic group. Table TI11 summarizes the data for optimal operation for each catalyst tested in the larger units, and Tables IX, X, and XI give the per pass yields obtained with the multiple tester in screening the periodic system. I n the following discussion of catalytic activities by periodic group certain pertinent preparative details are included (conditions of precipitation, drying, impregnation, and bulk densities), especially for the better catalysts of Groups IV and V. The efficiency of acetaldehyde consumption was usually much better than that of ethyl alcohol consumption. This difference was diminished (acetal deh y d e efficiency lowered and ethyl alcohol efficiency raised) by operating with higher concentration of acetaldehyde in the f e d , which increased the per pass yield of butadiene without effect on the ultimate yield, but decreased the cycle life of the catalyst due to accelerated carbonization. The major portion of the data was obtained in 8-hour runs a t 0.4 1.h.s.v. w i t h t h e commercially employed 2.75 to 1 mole ratio of ethyl alcohol to acetaldehyde feed; in general, the tabulations list only the yields for the optimal temperatures. Group I ( T i , Na, K, Cut Ag). Val ious

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INDUSTRIAL AND ENGINEERING CHEMISTRY

369

acetaldehyde. I n their discussion these authors misinterpreted the yield claim of Petrenko (%’), (Multiple-test unit: 4-hour runs: 0 . 6 1.h.s.v.) who claimed an ultimate yield Mole % per Pass Yield a t : of 70% instead of 43%. Feed Ratio Group I11 (B, Al, Tl). No 2.75/1 2/1 RRS-C 400” C. 350’ C. C. 350° C. effective catalysts were obtained Catalyst Composition Preparation 11 9-34 16 17 fn, 0.9Za 13 from Group 111. Borates of 13-28 27 20 13 agna‘ 0 46 24 SiOe aluminum, zinc, and zirconium 13-30 25 31 16 26 SiOt agna” 0 : 46 24 24 13-32 18 28 agna” 0.49 SiOn were tested. Alumina gel (RR22-26 376 6 19 19 agnb‘: 0.47 6 cgn, 0.72 7-380 16 11 10 C2-12) gave a 21% per pass and 6 12 7-44 22 akn, 0.44 12 a 29% ultimate yield a t 250” C., 7-44 1 akn 0.26 10 10 23 7-52 akn: 0.29 9 23 3 10 which was superior to the per7-80 21 1 a k n 0.37 6 10 7-82 1 akn: 0.46 23 6 6 formance of silica gel. Unsatis14-24 akn. 0.28 19 3 9 7 factory yields were obtained 17-24 2 19 akn; 0.35 1 0 7-98 6 11 akn, 0.42 32 20 14 with aluminum sulfate-silica 11-240 32 12 23 em, 0.68 25 11-260 21 26 21 em, 0.79 18 ($1): 12’% per pass and 25% 11-280 22 11 em, 0.44 22 20 ultimate. Alumina gel was 11-300 9 14 em, 0.63 17 14 tested as carrier for various pro22-14 M Fz fn 1.06 18 13 4 4 13-54 Ni5-95% SiOz ah& 0.45 16 20 9 18 moters, tantala included, with 13-56 15% NlS-85% Sloz ahn’ 0.56 17 15 18 67% SbzOa-38% AlzOs-5% Si02 19-62 6 13 12 20 ahn: 0.93 poor success. Two rare earth fno‘, 1.45 6-70 23 24 3 17 catalysts (2% CezO3-98% sioz, 7-34 13 20 23 bins’ 0 75 20 RR-C5-32 and 2.3% Ndz0315 16 25 11-2 20 agnf” 0 ‘ 3 8 11-4 9 13 agnf” 0 : 37 17 18 97.701, Si02, RR-C5-6) showed 11-6 9 11 20 16 agnf’: 0.38 11-8 cgoa’, 0.17 21 4 11 10 low activities. 11-10 ogma’, 0.59 22 43 30 36 Group IV (Si, Ti, Zr, Sn, Hf, 11-12 ogna’ 0 76 10 28 8 6 11-14 ogna?’ 0’73 40 18 37 30 Pb, Th). TITANIA-SILICA. Major 11-36 34 26 42 agna” 0’40 29 11-38 28 30 agna” o 45 31 40 emphasis was placed on silica, 11-56 29 21 27 29 bgna’: 0.54 titania, and zirconia. Several 11-72 21 23 25 23 agna’. 0 . 4 9 19-20 19 28 ahna’ 0 50 11 26 types of silica gel were tested as 19-22 17 26 a h n a ” 0‘45 15 28 19-24 26 33 33 ahna” 0 ’ 5 4 10 part of a carrier program. The 19-26 12 ahna” 0’73 24 0 11 maximal yields obtained with 22-38 17 12 oa’ 0’67 9 18 7-76 ahdd’b’ 0 45 22 27 14 20 silica a t 350 C. were 4% per pass 17-12 16 24 agnd‘a’,’ 0.44 11 24 17-14 22 20 agnd’a‘ 0 . 4 6 7 20 and 23% ultimate (RR-(31-22) 9-16 afnb’, 6 . 3 8 14 9 6 8 and 4% per pass and 32% ulti11-16 em 1.29 22 8 20 8 7-36 bin‘s’, 0 . 7 3 25 19 18 16 mate (RR-C16-62). Numerous ahmb’ 1 . 0 16 9-76 17 3 18 ahnb”0 49 34 9-78 20 25 31 titania-silica combinations were ahnb’: 0:49 32 9-80 24 24 28 tested with the object of obtain11-42 22 12 6 20 :pn;. ’900 50 19-42 14 27 30 32 a better carrier for tantala ing 19-44 21 ahnb’: 0:52 26 31 30 19-46 31 17 23 ahnb’, 0 . 5 4 33 than silica. The best of these a See Table VI11 page 367 for explanation of symbols. (RR-’26-20, 1% Ti02-99 % Sios, b 1 . 5 t o 1 feed ratio. 0 Celite from Johns-Manville Co. prepared by impregnating predried silica gel with titanium chloride) showed yields of 18% Group I combinations were found to be ineffective (less than 20% per pass and 52% ultimate a t 350’ C. Although this activity ultimate yield). Treatment of the commercial tantala-silica catawas considerably higher than that of silica alone, the ternary catalyst produced by promoting the dual carrier with 2 % of tantala lyst with sodium hydroxide was detrimental. However, copperand silver-promoted tantala-silica catalysts showed some merit was no better than the standard catalyst (2% T ~ Z O & SO2). B ~ ~ (discussed under Group V). ZIRCONIA-SILICA. Zirconia-silica combinations were studied Group I1 (Be, Mg, Ca, Ba, Zn, Cd, Hg). Each of these elements with regard to numerous variables of composition and preparation. was tested in several combinations. Some promise was shown The following brief summary illustrates the multiplicity of preby certain beryllia-silica, magnesia-silica (9, 7, 29, 28, 36),and parative details which are involved in the activity of a catalyst. magnesium carbonate-silica catalysts. A series of 16 magnesiaThe zirconia content was satisfactory over a wide range ( 3 to silica catalysts (SB-series) displayed optimal activity a t 375” C. 25%), impregnation in this series being accomplished by slurryfor magnesia contents varying from 3 to 70%; over this very ing silica hydrogel A with zirconyl nitrate and adding aqueous considerable composition range there was no critical change in ammonia as precipitant. One effect of raising the zirconia conactivity, the per pass and ultimate yields averaging 28 and tent was to lower the optimal operating temperature. Catalysts 55%, respectively. Two magnesium carbonate-silica catalysts impregnated with zirconyl nitrate operated a t lower temperatures prepared by wet ball milling showed maximal activity a t 400” than those impregnated with the oxalate. Catalysts impregC. (RR-(317-28, 25% per pass, 49% ultimate; RR-C14-22, 21% nated with zirconia-ammonium carbonate gave higher per pass per pass, 45% ultimate). Two magnesia, chromia-silica catyields of butadiene than those impregnated with zirconia-oxalic alysts (8% Mg0-50/, CrzOa-87% Si02, RR-C7-30, and 59% acid. Protracted drying below 100’ C. was detrimental-it was MgO-Z%Cr203-39% SiOz, RR-C2-26) were rather effective preferable to start the drying schedule a t 110” C. Six zirconiaagainst ethyl alcohol alone (26, 36, 4 2 ) but unsatisfactory for silica catalysts containing 0.6 to 3.0y0 of zirconia were prepared ethyl alcohol-acetaldehyde feed. Two zinc borate catalysts by zirconyl nitrate impregnation of commercial silica gels; showed low activities. Rigamonti and Cardillo (28) recently those catalysts were more active a t 350’ than a t 300’ C. Davireported a 58% ultimate yield of butadiene with a 60% MgOson silica gel 6953-80 was washed with nitric acid followed 40% Si02 catalyst, operating a t 350” C. and 0.4 1.h.s.v. on an by water prior to impregnation t o give a catalyst (RR-C16-20) ethyl alcohol-acetaldehyde feed containing 3 weight % of whose optimal operating temperature was 350“ C. (30% per

TABLE I X . CATALYST GIVINQGREATERTHAN 15% PER PASS YIELDSOF BUTADIENE IN TwoSTEPPROCESS

54

O

370

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Vol. 42, No. 2

that about 2% of tantala was optimal (see Table IX). Using (IJultipIe-test unit; 4-hour runs; 300" to 400° C., 0.6 1.h.s.v ; 2/1 to 2.75/1 mole feed ratio) this percentage of promoter, PrepaPrepaseveral B gels were dried to varyration RRS-C ration RRS-C Composition Composition ing silica contents before impregakn,a', 0.56" 7-94 er, 0.8sa 13-22 '0.) nation; the poorest activity rema 0.91 19-30 em, 0.97 13-38 ina" 1 10 19-32 ahn, 0 . 2 7 11-62 sulted from impregnating the 19-34 ina': lil in, 0.81 22-8 akna', 0.45 19-64 en, 0 . 8 7 14-4 most dilute gel (4% silica), and ahn, 0.49 9-36 0, 0.68 22-40 the best activities corresponded ahn, 0.69 9-38 0, 0 . 7 0 22-42 in, 0.77 19-6 to gels containing 10 to 20% ahn, 0 . 4 3 19-8 Si02 hn 1.21 6-74 ahn, 0 , 4 4 19-12 Si02 of silica. It became evident hn: 0.96 6-76 jr, 0.87 13-2 that the drying of the final hn, 0.68 6-78 jr, 0.95 13-4 in, 0 . 9 6 6-80 jr, 1 . 0 8 13-6 catalysts (starting with either A in, 0.84 6-82 jr, 1.11 13-8 in, 0.89 6-84 fn, 1.62 13-44 gel or B gel) should start at in, 0.97 6-86 ahn, 0 . 4 3 13-74 110" C.-that prolonged drling fn, 1.22 7-24B kn, 0 , 5 l 22-24 En 1 . 3 7-24C en, 0.34 17-26 below 100 C. was detrimental, jn: 0.88 7-644 akn, 0.42 7-100 in, 0.01 7-81R as was also found in the case of jn, 0.87 7-86 em, 0 . 4 8 20-32 zirconia-silica catalysts. Catajn, 0.81 7-88 kn, 0 . 4 6 19-50 In, 0.69 9-66 kn, 0 . 7 1 19-32 lysts whose drying schedules ajn, 0.49 20-10 a f n , 0.39 9-14 ajn, 0.51 20-12 started at 110' C. showed maxiahn, 0 . 4 0 9-20 k n 0 . 6 3 20-34 Si02 mal per pass yields and acetahm, 0.57 9-20-4 kn: 0 . 6 7 20-36 SiO? ajin, 0 . 4 3 9-94 en, 1 . 0 11-26 aldehyde efficiencies a t 350" C., in, 0.93 9-52 ahn, 0 . 7 8 9-68 ahn, 0.40 19-66 whereas catalysts which were ahn, 0 . 4 7 19-88 2,570 SiOrZ r 0 ~ - 2 2 5% . AlzOa-75% preliminarily dried below 100' C. ahn, 0 . 5 8 9-70 ahn, 0.50 19-70 in, 0.78 19-72 7.570 SiOrZrOz-17.5% &0a-75% did not reach optimal operation 9-72 ahn, 0 . 7 1 in, 0.89 9-92 in, 1 . 0 5 22-2 12.5% Si02 ZrOz-12.5% .11~01-75% until 400" C . The less drying ahn, 0 . 7 0 9-74 in, 0.86 22-4 before impregnation the bettez in, 0.90 22-6 Si02 ahn, 0 . 4 3 21-12 (for minimal operating temperaahn, 0.54 24-14 ture and maximal ultimate yield) ; See Table XI for exolanation of symbols. in other words, impregnation should take d a c e urior to shrinkage of the gel structure. The relative merits of precipitants for fixing tantala on the silica base pass yield, 50% ultimate yield); in the absence of the acid-water were evaluated: ( a )ammonium hydroxide, ( 6 ) hydrochloric acid, wash the optimal temperature was 400" C. Table XI1 lists a and (c) heat alone. Both of the chemical precipitants showed fen. illustrative examples. Several ternary catalysts containing some slight advantage in benefiting the per pass yield. For ex2% Zr02-8% Mg0-90% Si02 magnesia were tested-e.g., ample, Davison silica gel 6953-80 was impregnated in a 3.5y0 (RR-C2-50) and 2% Zr02-30% hlg0-68% SiOn (RR-C2-52). solution of tantala-oxalic acid and treated with aqueous aniThe former showed 27y0 per pass yield and 53% ultimate at monia. The catalyst contained about 2% of tantala; its ac285", which were the best results obtained a t this low temperativity against 2.75 to 1 ethyl alcohol-acetaldehyde feed was ture. A zirconia-thoria-silica combination (51) gave yields of poor, but its activity against 2 to 1 feed was good (44% per 26% per pass and 55% ultimate. pass). Lack of space prohibits discussion of the varied effects of HAFNIA-SILICA.It was late in the program before a source of numerous other preparative variables which were investigated. hafnia vas found (-4. D. McKay Company, New York, N. Y . ) DUPLICaBILITY O F C-4TALYST PREPARATION. six duplicate and time permitted the testing of only two hafnia catalysts. samples of Rubber Reserve silica gel were impregnated to give One of these was among the best tested (RR-C5-56, Table XIII). catalysts containing 1.1 to 1.3% of tantala. The preparative It was prepared by nitrate impregnation, whereas the less conditions were: impregnation in 3.5% solution of tantalaactive catalyst (RR-C5-58) was prepared by impregnating silica oxalic acid; decomposition and dehydration for 24 hours a t gel with an oxalic acid solution of hafnia (as in the standard 35" to l l O o , 5 hours a t 110' to 350", and 2 hours a t 350" to 375" laboratory preparation of tantala-silica cat,alysts). The optimal C. Each catalyst was tested for four successive 12-hour periods; operating temperature for both was 300" C. the yields (per pass and ultimate) and the efficiencies (ethyl Group V (V, Cb, Tal P, Sb, Bi). The main emphasis in Group alcohol and acetaldehyde) of the six catalysts agreed within 1%. V was on tantala. Several vanadium oxide-silica catalysts were However, when the tantala content was less than 1%-e.g., tested and found to possess low activities; three columbium 0.2 to 0.5%-the activities \yere not reproducible. oxide-silica catalysts based on three different types of silica ~IISCELLANEOUS PREPARATIONS. Of the numerous miswere found ineffective (maximal ultimate yield 40%). Alumicellaneous preparations tested, only a ferric chloride-set gel num phosphate-alumina (20y0 AlPO4-80% A120,), a commercial containing 1.9% of tantala (RR-C16-16, Table XIV) was of cat,alyst for the dehydration of ethyl alcohol, gave a small interest. This catalyst operated efficiently a t low temperatures yield of butadiene but the ultimate yield was low because of and after operating a t 350' 6. was successfully regenerated. excessive ethylene formation. Unsatisfactory yields of butadiene BEST LABORATORY-PREPARED TANTALA-SILICA CATALYSTS. were obtained with several antimony-silica catalj-sts and with the Table XV summarizes data typical of the best laboratoryone bismuth-silica catalyst tested. Alumina-silica, alumina, prepared 2% Ta20s-98% Si02 catalysts. It was evidently posFlorid, and Magnesol were unsatisfactory carriers for tantala, sible to prepare catalysts capable of 60% ultimate yield by a and the effectiveness of silica gel itself as carrier depended upon variety of methods. the method of preparation and impregnation. A discussion of TERNARY CATALYSTS.Cu0-TazOs-SiO2. Kumerous tantalathe relationship of catalytic activity to the type of silica gel silica catalysts with a third component were prepared and tested (gel A, gel €3, Dnvison gel, Rubber Reserve gel) and its processing, -e.g., commercial catalyst promoted with copper oxide (0.001, and of certain miscellaneous preparations and ternary catalysts 0.01, 0.5, 1.1, 3, and 10% of copper oxide). The performance of follows. catalyst containing 0.001 % of copper oxide was identical with lANTAL.4-SILICA. It was previously shown (4,27, 39, 40)

TABLE x. C.4TALYST GIVING8 T O 15%

PER P l S S

YIELDS O F BUTADIENE I N TWO-STEP PROCESS

O

Q

-

r7

-

February 1950

INDUSTRIAL AND ENGINEERING CHEMISTRY

371

INDUSTRIAL AND ENGINEERING CHEMISTRY

372

Vol. 42, No. 2

8% of magnesia benefited the catalyst for operation with 2 (8-hour tests) to 1 ethyl alcohol-acetaldeEffect of ZrOz content (SiOz-A) hyde feed. It was definitely Catalyst No. RR-C5-22 RR-(22-10 RR-C2-8 RR-'22-2 RR-C5-50 RR-C1-6 shown that preliminary drying 91.2 100 0 7 2.9 9 5 25 6 ZrOz, wt. % of a magnesia-silica gel-e.g., Catalyst temperature, C. 350 350 300 300 300 400 27 37 Per pass kield. % C4Hs 29 31 23 8 6 hours at 120 C.-before im35 9 48 53 55 52 Ultimate yield, % C4H6 35 39 Ethyl alcohol efficiency, % 43 45 30 6 pregnation with tantala was 46 17 77 86 64 66 Acetaldehyde efficiency, '36 detrimental. Effect of impregnant and diying schedule (SiOz-A) ZrOz-Ta20sSiOz. T e r n a r y Catalyst No. RR-C7-70a RR-C16-74b RR-Cl6-72C RR-CZ-48d RR-C2-24AB catalysts capable of 60% ulti3.8 2.3 1.9 2.2 2.0 ZrOz, wt. % ZrOz-(NHh)zCOs ZrOz-HpCzOa ZrOz-HzC~04 ZrOz-HSOs Zr02-€1 mate yield of butadiene were Impregnant 300 350 300 350 400 300 350 Catalyst temperature, C. 300 350 300 350 prepared from both A and 20 30 32 30 29 16 27 20 20 Per pass yield % CnHs 31 30 Ultimate yield % ~ 4 ~ 6 54 38 60 52 52 34 47 51 38 64 45 silica gels. Table XVI lists Ethyl alcohol &iicienoy 7' 49 29 65 44 50 27 50 43 27 60 35 Acetaldehyde efficiency: 3 65 60 61 70 59 49 49 60 69 66 69 the maximal yields of both a Drying schedule, 23 hours a t llOo, 10 hours a t 110-300°, 21 hours a t 300-360'. types of catalyst a t optimal b 23 hours a t llOo, 10 hours a t 110-300°, 6 hours a t 300-360'. t e m p e r a t u r e s . In general, c 162 hours a t !5O 3 hours a t 45-110°, 4 hours a t llOo, 10 hours a t 11003000, 6 hours a t 300-360'. d 6 hours a t 60 l h hours a t SOo,48 hour: a t l l O o , 24 hours a t 300-3.50 . 350" C. was optimal for A gels e 30 hours a t liOo, 90 hours a t 300-385 . and 300" C. was optimal for B gels; the optimal zirconia TABLEX I I I . ACTIVITYO F HAPNIA(2%)-SILICA (98%) content was different for the CATALYSTS (RR-C5-56) two types of gel. Incidentally, it mas shown that silica gel5 13-24 0-12 Hours on test 300 300 Catalyst temperature, ' C. which had been washed with 80% of the usual amount of water 27 31 Per pass yield % CnIX6 were equivalent to standard gels for the preparation of these 64 64 Ultimate yield, % C4He 60 57 Ethyl alcohol efficiency, % ternary catalysts. 75 79 Acetaldehyde efficiency, % Group VI (Cr, K, U, hIo, S). Two chromia-magnesia-silica catalysts were discussed under Group 11. One tungsten triFERRIC CHLORIDE-SET SILICAGEL TABLE XIV. IMPREGNATED oxide-alumina catalyst and several tungsten trioxide-silica [Holmes type ( 6 ) , RR-C16-16, 1.9% TazOs] catalysts were found to possess poor activities. The several Renenerated molybdena-silica catalysts tested were ineffective. Several Catalyst Fresh Catalyst 400 350 285 300 380 Catalyst temperature, C. urania catalysts were tested and found to possess mediocre 2 86 40 _ 5_ _. 17 26 Per pass yield, % C4H6 activities: 5% U03-95% Si02 a t 350" C. gave an ultimate yield 41 63 41 60 63 Ultiniate yield 7 CaH6 30 57 44 59 52 Ethyl alcohol kiciencv. 5% of 50%; 1% U08-2% Ta206-97% SiO, at 350" C. gave 31% 32 78 66 57 Acetaldehyde efficiency, % 42 1-8 1--48 1-48 1--8 1-8 Test period, hours per pass yield and 55% ultimate yield; 5% UO3--7.6% MgOOF ZIRCONIA-SILICA CATALYSTS TABLE XII. ACTIVITY

O

that of unproinoted commercial catalyst; larger amounts of copper oxide up to 10% were detrimental except in the case of 1.1% of copper oxide. Several samples of this 1.1% promoted catalyst were prepared and tested in order t o confirm this exceptional specificity; it would seem that this specificity is a fact. The ultimate yield was about 63y0 and the per pass yield was definitely higher than that produced by commercial catalyst; the high order of activity was maintained after four regeneiations. Mg0-Taz05-Si02. Three general types of this ternary catalyst were studied: seven catalysts with silica hydrogel -4; two catalysts with silica hydrogel B; and two catalysts mounted on commercial magnesium silicate. The third type was of low activity. For the first two types, magnesia was precipitated in a slurry of silica hydrogel from magnesium chloride by means of diethylamine, and the composite hydrogel was impregnated with tantala-oxalic acid; in other cases, slurries of silica hydrogen or chunks of silica gel were impregnated with an oxalic solution of magnesium carbonate-tantala. There vias essentially no difference in activity between catalysts containing 0.1 and 1% of magnesia, or between catalysts containing the X and B types of silica gel. There was some indication that the presence of 2 to

TABLE XV. Gel employed Catalyst No. Catalyst temperature, O C. Per pass yield, % C ~ H B Ultimate yield, % CaHs a

b C

d

TABLE XT'I.

MAXIMAL YIELDS

Yield, % T, Per UtiCatalyst C. pass mate ZrOz-Taz06-SiOz catalysts (gel A) 0 . 3 % Zr02-2.1Cj, TaaOs-97.6% sioz 350 11 48 (RR-C16-44) 50 0 . 7 % ZrOz-1.9% TazOs-97.4% Sioz 350 21 (RR-C16-46) 1.3% ZrOz-1.6% TazOs-97.1% si02 350 33 50 (RR-C16-98) 1.8% ZrOz-1.7% TazOs-96.5% SiOz 360 31 61 (RR-C16-48) 1 . 8 7 Zr0z-1.870 Tazos-96.5% SiOz 350 29 64 (Rlf-C16-48) 5 . 1 % Zr02-2.3% T a ~ O a - 9 2 . 6 7Si02 ~ 350 33 45 (RR-C16-82) 11.3% Zr02-2.1% TazOs-86.6% Si02 350 31 40 (RR-C16-84) 0.2% ZrOz-2.3% (RR-C16-28) 0 . 2 % ZrOz-2.3% (RR-C16-28) a, b 0 . 5 % ZrOz-l,9% (RR-C16-12) 1 . 8 % Zr02-2.0% (RR-C16-14) a b

Efficiency, yo Ethyl A c e s alcohol dchyde 52

48

47

60

40

75

57

71

57

80

36

66

30

67

ZrOz-TazOs-SiOz catalysts (gel B) Ta?Os-97.5% Si02 300 30 83

61

73

TazOs-97.5% BiOz

300

24

62

57

75

TazOs-97.6% Si02

300

27

54

48

68

Taz06-96.2% SiOz

300

29

52

45

66

48-hour test: all others vere 8-hour tests. Regenerated after 48-hour test.

BESTLABORATORY-PREPARED 2 % Tad&-98% Si02 CATALYSTS

Ba RR-Cl6-60 300 350 30 38 60 59

(8-hour tests) Ac Ad de Af Davison0.h RR-(31-2 RR-1-8 RR-(216-40 RR-C1-38 RR-C1-36 300 350 350 400 350 28 23 33 34 44 66 60 65 69 63 a Chunks washed with HC1 before impregnation. ' J Chunks untreated. U Impregnated catalyst treated with ammonia. h 211 feed.

Bb RR-C1-82 350

Chunks not dried before impregnation. Chunks partially dried before impregnation. Slurry dried and rehydrated before impregnation. Slurry not dried before impregnation.

39 60

Rubber Reservef RR-C5-54 350 38 67

FeCls-Set e RR-C16-16 350 40 63

February 1950

INDUSTRIAL AND ENGINEERING CHEMISTRY

87.4% SiOz at 350” C. gave 20% per pass yield and 34% ultimate yield (at 415” C. the corresponding yields were 29% and 31%). A nickel sulfide-silica catalyst is discussed under Group VIII. Group VI1 (Mn, C1, F). Two manganese catalysts (1.7% Mn02-98.3’% Si02 and 9.2% MnOz-90.8~o Si02) showed poor activities (37% ultimate yield). Certain halide-containing catalysts possessed some catalytic activity; aluminum fluoride was the best with 40 to 47% ultimate yields. Group VI11 (Ni, Ci, Fe). No satisfactory catalysts were obtained from Group VIII, although 15% NiS-85% SiOz showed some promise (18% per pass, 40% ultimate yield). *

.

ACKNOWLEDGMENT

The authors express their thanks to the Rubber Reserve Company, sponsor of this work; to M. W. Whitlock, D. H. Bishop, and G. J. Haddad for management of countless testing operations; to Michael Jaskowski, L. J. Lohr, and J. F. Miller for supervision of innumerable product analyses; to G. M. Diffendal, J. E. Gleeson, G. F. Haines, C. D. Helm, and F. M. Orlando for catalyst preparations and analyses thereof; and to W. A. Hamor and G. H. Young for administrative guidance. LITERATURE CITED (1) Barron, “Synthetic Rubber,” 2nd ed., New York, D. van Nostrand Co., 1945. (2) Butterbaugh and Spence, W. S. Patent 2,447,181 (1948). (3) Cass, Chem. [email protected], 26, 709 (1948). (4) Corson, Stahly, Jones, and Bishop, IND.ENG.CHEM.,41, 1012 (1949). (5) Hinckley and Sheppard, Anal. Chem., 19,771 (1947). ENG.CHEM.,17,280 (1925). (6) Holmes and Anderson, IND. (7) Ipatieff, U. S. Patent 2,374,433 (1945). (8) Jones, Stahly, and Corson, J . Am. Chem. SOC.,71, 1822 (1949). (9) Kagan, Lyubarskil, and Podurovskoya, Bull. acad. sci., U.R. S.S., Classe sci. chim., 1947, 173. (10) Kampmeyer and Stahly, IND. ENG.CHEM.,41, 550 (1949). (11) Krause, Kogan, and Kozlovskaya, Trudui Gosudarst. Opuit Zavoda Sintet. Kauchuka Litera B , I I I , Synthetic Rubber, 50 (1934). (12) Lebedev, French Patent 665,917 (1928) : Brit. Patent 331,482 (1929); Russian Patents 24,39 (1931); 35,182 (1934); German Patent 577,630 (1933). (13) Lebedev, Sotzialist. Rekonstruktziya i N a u k a , 3, No. 1, 127 (1933): J.Gen. Chem. (U.S.S.R.),3, 698 (1933). (14) Lebedev, Gorin, and Khutoretzkaya, Sintet. Kauchuk, 4, No. 1, (1935).

373

(15) Lebedev, Krause, Volzhinskil, Gorin and Neimark, Trudui Gosudarst. Opuit. Zavoda Sintet. Kauchuka Litera B , 111, 68 (1934). (16) Lebedev, Livshitz, Shul’ts, and Remiz, Ibid., IV, 3 (1935). (17) Lebedev, Koblyanskii, Andreev, Gorn, Livshitz, Sibiryakova, and Slobodin, Ibid., III,41 (1934). (18) Lebedev, Koblyanskii, Andreev, Volzhinskil, Gorin, Gorn, Kibirshtis, Sibiryakova, and Slobodin, Ibid., 111, 44 (1934). (19) Lebedev, Volzhinskii, Kibirkshtis, Koblyanskii, Krause, Krup(20) (21) (22) (23) (24) (25) (26) (27)

uishev, and Slobndin, T r u d u i Gosudarst. Opuit. Zavoda Sintet. Kauchuka Litera B , 111, Synthetic Rubber, 7-18 (1934). Manufacturing Chemists’ Association of United States, Washington, D. C., “Chemical Facts and Figures,” 2nd ed., 1946. Maximoff and Canonici, Brit. Patent 535,678 (1941); U. S. Patent 2,297,424 (1942). Natta and Rigamonti, Chimica e industria, 29, 239 (1947). Office of Rubber Reserve, Method L.M. 2.1.1.7 (or 2.1.1.9). Office of Rubber Reserve (R.F.C.), Report on the Hubber Program, Supplement 1 (1945). Ostromislensky, J . Russ. P h y s d h e m . Soc., 47, 1472 (1915). Petrenko, Kauchuk i Rezsina, 4, 1 (1940). Quattlebaum, Toussaint, and Dunn, J . Am. Chem. SOC.,69, 593

(1947). (28) Rigamonti and Cardillo, Ann. chim. applicata, 37, 347 (1947). (29) Rubber Director’s Report, Washington, D. C., Supt. of Dooumenta, 1945. (30) Shepherd, Schuhmann, and Diebler, J. Research &VatZ. Bur. Standards. 39.435 (1947). (31) Spence, Butterbaugh,’and ’Kundinger, U. S. Patents 2,436,125, 2,438,464 (1948). (32) Stahly, Ibid., 2,439,587 (1948). (33) Stahly and Corson, Rubber reserve fellowship, Mellon Institute,

unpublished data. (34) Stahly, Jones, and Corson, IND. ENG.CHEM.,40, 2301 (1948). (35) Szukiewicz, U. S. Patent 2,357,855 (1944). (36) Talalay and Magat, “Synthetic Rubber from AlcohoI,” New York, Interscience Publishers, 1945. (37) Talalay and Talalay, Rubber Chem. Technol., 15, 403 (1942). (38) Tamele, Byck, Ryland, and Vinograd, Division of Colloid Chemistry, 110th Meeting, AM.CHEhI. Soc., Chicago, Ill. (39) Toussaint and Dunn, U. S. Patent 2,357,855 (1944). ENG.CHEM., 39,120 (1947). (40) Toussaint, Dunn, and Jackson, IND. (41) Treszczanowioz, Przmysl Chem., 27, 14 (1948). (42) Weiss Report, U. S. Senate Hearings, Subcommittee on Agriculture and Forestry, Dee. 17, 1942, pp. 1258-61. (43) Whitlock, Haddad, and Stahly, Anal. Chem., 19, 767 (1947).

RECEIVED June 7, 1948. Contribution of Multiple Fellowships on Catalysis (Office of Rubber Reserve, Reconstruction Finance Corporation, Washington, D. C.) and Tar Synthetics (Koppers Company, Inc., Pittsburgh, Pa.).

Enthalpy-Concentration Diagram for Ethylene Glycol-Water J

J

JU CHIN CHUl AND W. J. YANG Washington University, S t . Louis, M o . Anenthalpy-concentration diagram coveringliquid, vapor, and the two-phase region is constructed from the following data: molal heat capacity at constant pressure of pure water and pure glycol in both liquid and vapor phases, and of the liquid mixtures at several concentrations; heat of solution at 62.6” F.; latent heat of vaporization of pure water and ethylene glycoI; and bubble point concentration and dew point concentration curve. Molal heat capacity of glycol vapor, critical temperature, and heat of vaporization of glycol under 228 mm. of mercury, not available in the literature, are calculated from the most reliable thermodynamic correlations. The temperature 1

Present address, Polytechnic Institute of Brooklyn, Brooklyn, N.

Y.

covered ranges from 60” to 480’ F. Although the diagram is constructed at a total pressure of 228 mm. of mercury, it can be used at other low pressures.

T

HE design calculation for the distillation of a binary system can be handled exactly and conveniently only by the socalled Ponchon-Savarit method (8,9), involving the application of an enthalpy-concentration diagram which is a convenient graphical substitution for both material and heat balances involved in distillation as well as other unit operations in chemical engineering. The usefulness of an enthalpy-concentration diagram in solving other problems involving heat effects accompanying concentration changes in a binary system is also well known ( 4 , 7 ) . I n view of the importance of ethylene glycol ( 2 ) ,i t is desirable to