ow as 6OOOF. Pressures are 20 to 30 p.s.i.g. Saturated ulfurvaporat 1180°F.contains210/0diatomic, 58’%hex- tomic, and 21y0 octatomic molecules (9). However, vailable kinetic data are correlated satisfactorily by ssuming a second order reaction between methane and

diatomic sulfur which Is probably the true reactant. Activation energies of 61,920 and 68,940 B.t.u. per

pound-mole have been reported. At space velocities of 600 standard cubic feet per cubic foot per hour, catalytic reactora generate 35 pounds of carbon disulfide per hour per cubic foot of catalyst. Some plants are designed to operate on the exothermic and some on the endothermic side of the adiabatic reaction temperature of about 1200’ F. Heating the reactants (neglecting heat losses) requires about 1650 to 1750 B.t.u. per pound of carbon disulfide product.

Carbon disulfide can be made from methane and sul- fur by either a high or low pressure purification process (Figure 1). In either case, the methane should contain less than 1% propane and heavier hydrocarbons and no more than 2% ethane. The high pressure process is especially applicable for small plants where recovery of hydrogen sulfide is uneconomical and where the hydro-

Coils in the sulfur vaporizer are of high-chrome steel, and the reactor also is preferably of this material. Dis- tillation towers in the purification section can be of car- bon steel.

ne^ Me~hods

CARBON 9 DISULFIDE Emphasis in raw materials shf ts further from charcoal to methane, but impact of new processes using coke or liquid petroleum fractions

remains to be seen

3

H A R R Y W . H A I N E S , J R . gen sulfide may be used elsewhere as a reactant.

variety of reactions are available for making carbon A disulfide, but only two have become important commercially; one is from carbon and sulfur and the other from methane and sulfur. The classic method uses charcoal and sulfut--heat is applied with carbon electrodes to a hearth or to retorts directly fired by natural gas, producer gas, or other fuels. Recently, however, especially in the United States, production from methane and sulfur has become more common.

Considerable data on carbon disulfide are available in the literature, including a description of both routes of manufacture (6). An excellent thermodynamic analysis of both the methane and charcoal routes is given (7) and, for the methane route, thermodynamic and kinetic data are available (2, 8) as well as kinetic data for plant design (7,3). Thermodynamic properties of sulfur ( 7 I), carbon disulfide (5), and hydrogen sulfide (10) are tabulated in the literature.

Although the methane route has many advantages over the charcoal method, incentives to develop new processes still exist, particularly for foreign areas where low cost methane is unavailable. An inventor of the original methane process, Carlisle M. Thacker, is work-

METHANE ROUTES FOR MAKING

REACTIONS FOR MAKING CARBON DISULFIDE ( 4 )

F. CH, + 4/nS. = CS, + 2HIS c + z/ns. = cs, ZCO + 2/nS. = 2 c o s = cs, + CO, c + zn,s = csI + ZH, 5C + ZSO, = CS, + 4CO

1050-1300 1200-1550 800-850

2025-2075 2250-2300

Methane RoulhProcess Technology

To obtain satisfactory reaction rates, most plants use temperatures above 1000° F., although stoichiometric convenion is theoretically possible at temperatures as

44 I N D U S T R I A L A N D ENGINEERING CHEMISTRY

However, this production picture may be affected by an impending merger. Regenerated cellulose consumes about 80% of the total carbon disulfide output; this is a big factor in the planned acquisition by FMC Corp. of American Viscose, a leading rayon manufacturer which has also one fourth of the nation's cellophane capacity. FMC may have a better chance than Stauffer Chemical which was thwarted by the Justice Department last year from acquiring American Viscose. If FMC is successful, considerable plant expansion may result.

ing on a technique for making carbon disulfide from liquid petroleum fractions, and has patents pending.

His purification system is reported to be nearly the same as those in conventional plants using kerosine as lean oil. Sulfur is vaporized, but Thacker has not indi- cated the degree of superheat added to the petroleum fraction or reactor operating temperatures. He claims a lower raw material cost, a higher yield of carbon disul- fide, less preheat, and lower purification costs.

Shawinigan Chemical also has a new method based on its Fluohmic furnace, a resistance-heated fluidized bed. Sulfur or hydrogen sulfide may be used as the reactant

produced when gaseous sulfur, or liquid sulfur which va- porizes as it enters the chamber, flowed upward through a coke bed heated to 2000O to 2200' F. Other labora- tory tests showed that about 70% of the hydrogen sulfide fed to a coke bed was converted to carbon disulfide at 2700' to 2750' F., with apparent efficiencies of 90 to 100%. In some tests efficiencies actually exceeded loo%, because sulfur in the coke entered the reaction.

Economic Aspects

. and in laboratory tests, conversions up to 70% were

2

Total carbon disulfide capacity in the United States is difficult to estimate (Table I), but the shift from charcoal to methane is marked. At one time Stauffer Chemical had seven charcoal plants in operation and DowChemical operated one at Midland, Mich. Because of this shift and lower costs, production of carbon disulfide, since 1958, has been increasing about 6 to 7% per year. One 50 million pound-per-year plant is under construction.

TABLE 1. CARBON DISULFIDE PLANTS

Capaity,* Millim D./Y, .

<m 100

Coptive Captive

<IO

50 10

340-360

6W6B ~

Combanv Rous Mafm

Charcoal

Methane

Charcoal Chorcoal

Methane

Methane Methane

Methane Chorcoal

,J. T. Baker Chemical Penn Yan, N. Y.

FMC Corp. & Allied Chemical So. Charleston, W. Va.

Old Hickory Chemical Old Hickory, Tenn. Richmond, V O . ~

Pennsalt Chemical Houston, Tex.

Pittsburgh Plate Glass Natrium, W. Vo." So. Charleston, W. Vo.'

Stauffer Chemical Delaware City, Del. Lowland, Tenn.

Total

LI Estimofed. * E l e ~ f r o l h i r m n l p ~ ~ ~ s s , Retort proccss. schcd- ded for shufdnwn in 7963. Due on strmn in 1963.

(Confinucd on nexf p q c ) AUTHOR Engimn and owner of Haims t3 Assnciater in Houston, Tex.

Harry W. Haims, Jr., is a Consulting Chcrnical

CARBON DISULFIDE - :%Wtal-

- I I \ i I I l - f l

Figtrrc 1. Sulfur vapors p a s fhrough fhe calaly~f chamber of 1200° IO lwOo F. ond (I rpom velocity of 5W lo 600 standard cubic feel pn cubic fool pn hour. Corbon dim@de is formcdawording to fhc reoclim C H , +

4/nS, = CS, + 2 H d . Thc produ6 is couslic-moshcd b t f m goi?i,$ lo sloroge. In 6hc high pressure proccrr, the mea circled obom ir replactd by 6he reefion in color at I4f t

Mosr planfs use 5 f o 70% errersrulfur.

VOL. 5 5 NO. 6 JUNE 1 9 6 3 45

Although prices have remained firm for many years, carbon disulfide growth rates have lagged behind those of carbon tetrachloride (Figure 2). Two main factors are responsible: demand for the tetrachloride in making fluorocarbons is strong, and carbon disulfide’s rayon markets are barely holding their own against major in- roads by nylon tire cord.

For carbon tetrachloride, capacity is equally difficult to estimate, because of the variable output obtainable from methane chlorination. Trade estimates now are as high as 570 million pounds per year, but previous figures were about 400 million. Annual production increases of 6% are predicted for the next five years, even though carbon tetrachloride seems destined to remain a one- product commodity (fluorocarbons). That about 35% of total output is derived from carbon disulfide is reason- ably safe to assume: Diamond Alkali operates a 60- million-pound-per-year plant; FMC Corp., a 50-million; and Stauffer, now operating a 100-million-pound plant, plans to put on stream in 1964 a 70-million-pound plant.

Despite the declining tire cord production, however, rayon output is moving upward (Figure 3). But its future is difficult to predict. Since Du Pont dropped

CARBON OISULFIDE PRODUCTION

looo/--- ~~~~~ I

1955 1957 1959 1961 1963

Figwe 2. Growfh of carbon didJide production lugs behind that of carbon tchachlmidc

CARBON DISULFIDES MAJOR OUTLETS

700

J 1963

Figwc 3. Vkosc rayon ir still fhc !coding ouflel for carbon dmlrfuic oym W ~ A U ~ Y ~

Ab INDUSTRIAL AND ENGINEERING C H E M I S T R Y

v 0

Carbon disu@dc u c poftm

out, only four producers are left: American Enka, American Viscose, Beaunit Mills, and Industrial Rayon.

This year marks the end of an era for Du Pont, which entered the rayon business 33 years ago at Buffalo. The company now has a “radically” new nylon which it claims reduces “significantly” flat spotting in tires. If this is so, nylon may be headed for the original automo- tive equipment market-the last stronghold for rayon tire cord. Du Pont estimates that nylon cord is now used for about 70% of the replacement tires on auto- mobiles and trucks, 40% of original equipment truck tires, and 100% of airplane and off-the-road tires.

Producers of rayon for uses other than tire cords in- clude Celanese, Courtaulds (Ala.), Fair Haven Mills, Hartford Rayon, and Mohasco Industries.

Meanwhile, cellophane continues to consume more carbon disulfide. Recent predictions indicate a prob- able output of 500 million pounds during 1967. At present, three manufacturers have an estimated capacity of 540 to 580 million pounds per year: American Viscose, 150 million; Du Pont, 320 to 350 million; and Olin Mathieson, 70 to 80 million.

Worldwide, demand for carbon disulfide continues up- ward but the United States exports very little-less than 1.3 million pounds in 1961. Of this, 672,000 pounds went to Canada, 445,000 to Colombia, and the balance was distributed among 12 other countries.

SUGGESTED READING

(1) Fisher, R. A,, Smith, J. M., IND. ENG. C~elr . 42, 704-9

(2)?~k~~,5%. O., Miller, E., Hennig, H., Zbid., 42, 2202-7

(3 Fomey, R. C., kmith, J. M., Ibid., 43, 1841-8 (August 1951). (41 Madon, H. N., Strickland-Constable, R. F., Ibid., 50, 1189-92

(5) O’Brien, L. J., Alford, W . J., Ibid., 43, 506-10 (Februay

(November 1950

(August 1958).

W., IymldPelrol. 31,62-68 (June 1960). IND. END. CHEW. 41,1968-73 (Scptembcr 1949 M., Miller, E., Zbid., 36, 1824 (February 19441: ,... ~~ :., ., . ’

(9) Tulla, W. N., “The Sulphur Data Book,” p. 27, McGrawA .J”.

~

10 West, J. R., C h . Erg. Pr.gr. 44,287-92 (April 1948). 11 West, J. R., IND. ENG. CHEU. 42,713-8 (April 1950).

>V‘ I ~ ,’ .. New York, 1954.