T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
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NOTES-A blank test shall be made heating t h e same length of time under t h e same conditions as in t h e regular determination, a n d using t h e same amount of all reagents in each step of t h e test. Thk asbestos m a t on t h e Gooch crucible used in filtering the barium sulfate should be prepared as follows: Finely cut Tremolite (Italian) asbestos is shaken up with water a n d a n asbestos m a t deposited under SUCtion on t h e Gooch. T h e m a t is washed with dilute acid, dilute alkali, a n d distilled water, a n d t h e crucible ignited. T h e washing a n d ignition are repeated t o constant weight. A Gooch prepared in this way is quick a n d accurate, quick because of speed of washing and t h e fact t h a t there is no paper '50 burn off, a n d accurate because there is no chance of reduction of barium sulfate b y t h e carbon of filter paper.
Vol.
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No. 9
or nearly nine times t h a t of t h e finished product, using t h e generally adopted process a n d working with fair economy.' To say t h a t i t is a n extravagant process is t o p u t i t mildly, b u t i t has maintained itself with considerable obstinacy in t h e face of many a t t e m p t s t o improve a n d shorten it. Fig. I shows t h e old process diagrammatically. It Producfs
By -Froduds
THEBARRBTT COMPANY 17 BATTERY PLACE,NEW YORKCITY
SYNTHETIC PHENOL' By ALBERTG. PETERKIN, JR. Received July 20, 1918
It is difficult t o estimate t h e quantity of any of t h e products from coal t a r which is available, because, on the one hand, the production of t a r is changing from d a y t o day, due t o t h e continued increase in t h e number of coke ovens, and on t h e other hand, its consumption for fuel purposes is affected b y greater or less difficulty in obtaining supplies of coal. It is safe t o say, however, t h a t it would not be practical or even possible to-day to make more than five t o six million pounds of phenol per year available from this source. T h e United States used before t h e war some 5,000,ooo lbs. of phenol per year, t h e consumption being divided among pharmaceuticals, resins of t h e Bakelite type, dyestuff intermediates, and t h e explosive, picric acid. A t the beginning of the war, t h e demand immediately increased, due .to the increased manufact u r e of picric acid. T h e French Government, particularly, became a large customer of manufacturing concerns in this country, both for phenol and picric acid. T h e production a t t h e time just before t h e entrance of this country into the war had jumped t o something like 7 2 , 0 0 0 , 0 0 0 lbs. of phenol per year. It is likely t h a t 1919 will see a very great increase in t h e production of phenol in this country. Coal t a r as a direct source of phenol is therefore a negligible factor in view of t h e present demand. Whatever the merits of picric acid as a n explosive, a real objection t o its manufacture in such times as these lies in the relatively enormous amount of raw materials involved, a n d t h e necessity for t h e correspondingly great consumption of our valuable transportation facilities. For example, t o make IOO,OOO,ooo Ibs. of synthetic phenol requires in round numbers:
.................................... ...........
Benzol Fuming sulfuric acid (91/~per cent) Caustic soda,. Lime Limestone. Coke 8 Niter cake..
............................. ..................................... ................................ ........................ ............. ...............................
TOT&
................................
Pounds 115,000,000 280 000 000 18O:OOO~OOO 42 000 000 I~O:OOO:OOO 35 000 000 42 000 000
: :
884,000,000
1 Read before the American Institute of Chemical Engineers, at Berlin, N. R., June 21, 1918.
Fro. I-CHART SHOWING THE OLDSYNTHETIC PEENOT. PROCESS
Sept., 1918
T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
spent A o d f o Storaqe M S A to
Neutral, r e r
FIO.11-DENNIS-BULL PROCESS
has been described many times and a bare outline will suffice now. Benzol is sulfonated a t temperatures varying from 50' t o 70'. The strongest acid t h a t may be used with economical results, in t h e writer's opinion, is fuming sulfuric acid containing g1/2 per cent of free SOs, the limitation being enforced by t h e necessity of avoiding the formation of diphenylsulfone. Since the composition of t h e spent acid from the sulfonation is a constant, t h e amount of sulfonic acid necessary for the completion of the reaction is increased very largely as the concentration of the initial acid is decreased. It has not been considered economical, therefore, t o use acid weaker t h a n one containing 98 per cent HzS04. The figures given above are for the higher concentration. The result of t h e sulfonation is a solution of sulfonic acid, sulfuric acid, and water. The sulfuric acid and water together make a spent acid of approximately 80 per cent HzS04 and 2 0 per cent HzO. The Solution then contains, in round numbers, 60 per cent sulfonic acid and 40 per cent spent sulfuric acid. The sulfonic acid is required in the form of sodium salt. The procedure in all plants is essentially t h e same, although many minor variations have been adopted. Slaked lime is placed in the agitators and the mixture of sulfonic and sulfuric acid slowly added during agitation. The sodium salt may be formed by addition of sodium sulfite obtained from
I
73 9
the fusions later in the process. When this procedure is adopted, t h e mixture in t h e agitators consists of a water solution of sodium benzosulfonate and a mixture of solid calcium sulfite a n d calcium sulfate. The whole is heated t o 115' in order t o obtain the sulfate in proper crystalline form for filtering, and is passed through t h e filter presses. The resulting solution of sodium benzene sulfonate contains approximately I 2 per cent of the salt and small quantities of calcium sulfate, due t o the slight solubility of this material. It is important t o remove all calcium salts, both for t h e sake of the tubes in the evaporators and because of t h e havoc they cause in the fusion operation. This is accomplished by the addition of t h e necessary small
Fro. IV-SULFONATORS.SIDEVIEW
FIG.111-SULFONATORS TOPVIEW
amount of sodium carbonate and refiltration. Some factories make the soda salt in two steps, adding sodium carbonate t o the filtered solution of calcium benzosulfonate; others add only the amount of lime necessary t o react with the sulfuric acid, in making t h e soda salt in one step, which makes t h e use of the by-product sulfite difficult, due t o the liberation of SOZ. The I O per cent solution is evaporated down t o the saturation point, and the salt obtained from the syrup by means of drum dryers. The salt, preferably retaining about I O per cent of water, is fed into melted caustic soda in the fusion kettles, there being about one mole of soda in excess. The temperature during the fusion is maintained between 320' and 3 5 0 ° , the salt being fed in slowly during t h e operation. 320' C. appears t o be the critical temperature of the reaction. As the result of t h e fusion, a light brown
J
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
740
FIG.V-AGITATORS
liquid mass with the appearance of melted chocolate is obtained, which is poured hot into such an amount of water as will dissolve t h e phenolate and leave the sodium sulfite in solid form. This is done in vessels marked “dissolvers,” which are provided with stirrers. Only about I O per cent of the sulfite formed remains in the solution and this amount can undoubtedly be decreased. The phenolate liquor is filtered from the sulfite on open sand filters. The sulfite is agitated with water, separated by means of filter presses, washed free of phenol, and marketed as a n impure sodium sulfite. A typical analysis of this material is:
...................................... ..........................................
Moisture. N404
.................................. ................................ ..................................
2 0
Vol.
No. 9
means of carbon dioxide in one operation unless such a large excess of C o t is introduced as t o transform all the carbonate t o bicarbonate, which is undesirable. When t h e passage of the gas is discontinued, t h e phenol layer contains in solution about I O per cent phenol as sodium phenolate, while t h e carbonate layer is free from phenolate but contains approximately 2 per cent of phenol. T h e carbonate is completely freed from phenol by means of a steam distillation; a 4 per cent solution of phenol is obtained in this way. The crude phenol, containing I O per cent of phenolate, may be completely acidified with COZ, by replacing the carbonate solution with water. Niter cake, however, used as a n acidifying agent, has t h e advantage of simultaneously removing a large percentage of t h e water present. The dehydration reduces the water content of t h e crude phenol from 3 0 per cent t o less t h a n 14 per cent, and relieves t h e refining stills of a great burden. The crude acid is placed in a simple still from which is obtained a first fraction of water and phenol, a middle fraction of pure phenol, and a residue of the more complex phenolic bodies formed in t h e fusion. The synthetic phenol produced is exceedingly pure; it is comparatively easy t o obtain material melting a t 40°. Redistillation gives a product melting a t 40.6’ C. The true melting point of pure phenol is in our opinion 40.8’ C. The great economies possible in t h e process are obviously to be made in t h e cutting down of the Ioo per cent of sulfuricacid, the reclaiming of the caustic soda, and the marketing of the sodium sulfite in a useful and valuable form. The maximum yield
I
Per cent 24.20 7.12 62.30 0.46 0.60
The wash water is used in the dissolvers so t h a t its sulfite is deposited again on the filter beds. The phenolate liquor is carefully diluted t o a gravity corresponding t o a phenol content of about 16 per cent. This diluted solution is placed in a series of tanks. Thirty per cent carbon dioxide gas generated from a mixture of coke and limestone is ’passed through it. These so-called “blowers” are arranged SO t h a t the gas may pass from one t o another in any direction desired. The strong gas goes first through the almost neutralized phenolate and leaves from a strongly alkaline solution, thus avoiqing any possibility of loss due or pressure of phenol a t the.temperature of the s involved, which is about 50’ C. It is not possible‘ t o entirely neutralize the phenolate solution by
IO,
FIG. VI-EVAPORATORS.DISSOLVERS
S3pt., 1918
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
FIO.VLII-DRUM DRYERS
FIG. VII-RECORDINGGAUGE,AUTOMATIC TEMPERATURG CONTROL
.
which has been claimed for t h e process is about 80 per cent. Our work has shown t h a t t h e fusion operation alone will not yield more t h a n go t o 92 per cent of t h e theoretical, and in practice it is difficult t o maintain this high standard. Under present conditions, t h e average American practice probably results in a total over-all yield of between 6 0 per cent and 7 5 per cent. As chemical processes go, t h e process requires a n inordinate amount of labor and the repeated handling of t h e material gives ample opport u n i t y for mechanical losses, particularly in view of t h e rcstlessness of workmen under' present conditions. Two methods have been suggested t o reduce or conserve t h e excess of sulfuric acid used. Daniel Tyrer of England (U. S. P a t e n t No. 1,210,725) passes
ing between 100' and 185' C. T h a t part of t h e benzol vapor not reacted upon carries with i t t o a condenser the water of reaction, and so gives a constant concentration t o t h e sulfuric acid, keeping it active. Tyrer claims in this way t o get about 80 per cent of the amount of sulfonic acid theoretically obtainable from t h e sulfuric acid used. This method has not yet been tried on a large scale in this country. The second method is t h a t of Dennis and Bull. Some two years ago, Professor L. M. Dennis,' of Cornel1 University, discovered t h a t although the solubility of pure sulfonic acid in benzol was negligible, benzol would take up from t h e mixture of sulfuric a n d sulfonic acids between 2 and 3 per cent of its own volume of t h e sulfonic acid. I n working out this idea, i t of T h e Barrett Company, occurred t o Mr. Hans
FIG.IX-FILTER PRESSES
benzol vapor through sulfuric acid of as low concentration as 90 per cent HzS04, a t temperatures vary-
741
FIG.X-GENERAL ARRANGEMENT DENNIS-BULL PROCESS 1 2
U. S. Patents 1,212,612,'1,211,923, 1,227,894, 1,228,414, 1.229.593. U. S Patents 1,247,499, 1,260,852,.208,632.
742
T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
FIG. XI-WASHERS
t h a t the sulfonation could be made simultaneously with t h e extraction. These ideas have been utilized in the evolution of a n extremely simple process which not only saves go per cent of the excess sulfuric acid as a spent acid containing 7 0 t o 7 7 per cent HzS04, b u t eliminates a good percentage of labor, all t h e lime, and substantially reduces t h e deplorable cost of repairs, due t o t h e many moving parts of t h e old installation. The process will be easily understood from Fig. 11. The vessels I , 2 , 3 and 4, so-called “extractors,” each contain a t rest a layer of a solution of sulfonic and sulfuric acids of varying proportions. T h e benzol passes continually upward through this series of extractors, t h e vessels being under a pressure equivalent t o t h e head of benzol. The distribution of t h e liquid in fine bubbles is effected b y means of perforated branch pipes. ’After the passage of t h e benzol for a certain length of time, the solution in No. I is free from sulfonic acid and consists of 7 7 per
FIG. XII-PUMPS
AND
Vol.
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No. g
ONLYWORKING PARTS
cent H~SOI. When this has been accomplished t h e so-called “spent acid” is withdrawn. The solution in No. 2 , which probably contains I O per cent of sulfonic acid, is dropped into No. I . The solution in No. 3, which contains probably 2 5 per cent sulfonic acid, is dropped into No. 2, and t h e solution in No. 4, which contains probably 40 per cent sulfonic acid, is dropped into No. 3. I n t o No. 4 is then slowly introduced a charge of 98 per cent sulfuric acid. T h e flow of benzol is not interrupted a t any time. Sulfonation takes place almost immediately and t h e volume of the benzol flowing through, approximately 2 0 0 gal. per min., is so great as t o effect almost instantaneous removal of the heat of reaction. The benzol is maintained throughout a t a temperature of 60’ C. This is accomplished b y heaters a t t h e bottom of t h e syst e m and coolers a t the top. After passing through t h e coolers, t h e benzol, which will contain approximately 2 per cent sulfonic acid, passes successively through the washers 5 , 6, and 7, containing water.
FIG. XIV-FINAL WASHTANKA N D RECEIVERFOR WATERSOLUTION OF FIG.XIII-EXTRACTOR
BENZENE SULFONIC ACID
Sept., 1918
T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
FIQ.XV-COOLERS
The benzdl falls from one vessel t o another by gravity, there being no pressure on this part of the system. The sulfonic acid remains in t h e water and the benzol leaves t h e last washer entirely relieved of its burden. It is passed t o large settling tanks where the rate of flow is slowed down t o such a n extent as t o allow the sulfonic acid solution, carried in suspension, t o settle, a n d from these tanks flows t o the pump and is forced through the heaters t o the extracting system once more. When such a n amount of sulfonic acid has been deposited in washer 5 as t o bring it t o the strength desired, i t is removed t o an evaporator and the solution from washer 6 pumped t o No. 5 , and t h a t from No. 7 t o No. 6. Fresh water is p u t into No. 7 . A water solution of sulfonic acid can be obtained containing 60 per cent or even more sulfonic acid and contains also about 2 per cent b y volume of benzol in solution. The benzol is removed by evaporating a small percentage of the water. The solution of sulfonic acid is then neutralized, either by the carbonate solution from t h e phenol blowers or with the solid sulfite of soda. The sodium benzosulfonate obtained contains some 5 or 6 per cent of sodium sulfate, due t o the solubility of sulfuric acid in t h e benzol solution of sulfonic acid (one p a r t sulfuric t o twenty parts sulfonic). The advantages of t h e process are obvious. The initial cost of the plant is about 50 per cent of the old style plant, which it displaces, i t runs practically without attention,
7 43
and requires from one-third t o one-fourth the number of laborers. Taking for granted complete extraction of the sulfonic acid, which proves quite possible, and a removal of the benzol from the water solution of sulfonic acid, the losses possible are confined t o mechanical causes, t h a t is, either leaks or evaporation. The yield under the old process, from benzol t o sodium benzosulfonate, is about go per cent. The new process makes easily possible a yield of 98 per cent, leaving the mechanical losses out of consideration. The formation of disulfonic acid and of sulfone is negligible. The spent acid is concentrated t o 93 per cent and used repeatedly. The operations ( I ) discontinuous sulfonation, ( 2 ) liming, (3) filtering, and (4) evaporating, involving complex machinery and many moving parts, have all been displaced with t h e one simple and continuous operation, extraction and sulfonation going on simultaneously, the only moving parts being two small pumps. The enormous simplification of the process achieved will be made more evident by photographs t h a n by any description. Another improvement in t h e process, very generally adopted, has been t h e so-called “liquid fusion,” by means‘of which the drum dryer, with its dust and spatter, hap been eliminated. “Liquid fusion” consists in t h e introduction of a saturated solution of sodium benzosulfonate directly into liquid caustic soda a t a point above the reaction temperature. T h e reaction, when the temperature is properly . controlled, goes even more smoothly t h a n with t h e solid, since there is no tendency t o dust and float, and t h e r a p i d evolution of t h e steam gi,ves better agitation. T h e fusion is asgreat source of loss in yield. Well-conducted fusions, where the temperature has been kept down and which for t h a t reason show no evidence of oxidation, give between 86 and go per cent yield. Our experience shows t h a t using the liquid fusion method a high yield is more easily obtained t h a n with t h e d r y salt. So much for innovation. Another important economy t o be achieved in this process, and one even
FIG. XVI-SETTLINGTANKS
*
7 44
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
more important t h a n t h a t of sulfuric acid, is t h a t of caustic soda. Neutralizing the phenolate with sulfuric acid, as is often done, is a gross and inexcusable waste. Providing t h a t t h e lime can be utilized, t h e difference in cost between t h e neutralization with COa, as generated from limestone a n d with sulfuric acid, is immeasurably in favor of t h e former and t h e operation is exceedingly simple, once t h e necessity for clear solutions is understood and t h e fact of t h e solubility of phenolate in phenol. If any salts are precipitated b y t h e carbonation of t h e phenolate, a n emulsion is obtained from which t h e phenol will settle only with great difficulty. T h e avoidance of this emulsifying is merely a question of dilution, however, a n d no real obstacle is involved. T h e soda, not only of t h e phenolate, b u t t h e excess soda, is obtained in t h e form of a weak solution of sodium carbonate, which can be readily causticized a n d made available at t h e plant for t h e fusion operation. T h e fusion reaction is: CCH&OaNa
.
+ zNaOH
= CsH50ru’a
+ NaaS03 f
HzO
If half of t h e sulfite is used for the formation of t h e soda salt, only one moleculLe of soda is consumed a n d this goes out of t h e plant in t h e form of sodium sulfite, a useful a n d marketable product.
Since in t h e
Vol.
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No. g
Dennis-Bull process, SO2 is evolved from t h e neutralization of t h e sulfonic acid when sulfite is used, it is possible also t o produce bisulfite of soda. The large amount of limestone needed is not a relatively important objection from t h e point of view of cost, b u t i t presents a transportation problem of considerable magnitude. T h e disposition of t h e calcium carbonate sludge from the causticization may involve considerable expense. From t h e transportation point of view alone, t h e calcination of t h e carbonate sludges, in rotary kilns, as a source of COZa n d of lime, is justified. This has been successfully tried in connection with other operations and has been found economical in districts somewhat remote from t h e limestone fields. Were t h e various economies indicated takefi advantage of there would result a startling decrease of raw materials
............................ ............................ ..................................... ................................
D~CREASE Per cent
Sulfuric Acid.. Caustic Soda.. Lime Limestone..
40 60 90 100
and a corresponding decrease of tonnage to‘ be transported from a total of 884,000,000 t o 397,214,400per million pounds of phenol, or about 5 0 per cent. THEBARRETT COMPANY 17 BATTERY PLACE, N E W YORKCITY
B y A. MCMILLAN, 24 Weatend Park St., Glasgow. Scotland
FAN DYNAMOMETER BRAKE
NEW VOLTAIC CELL
In the fan dynamometer of SW. G. Walker and Co., Emeryhill St., London, intended for measuring the brake horsepower of aero and other engines, the power is absorbed by revolving the instrument in air. The device consists of a pair of jaws or arms, made of well-seasoned ash, adapted to grip at their central part or propeller hub. The blades, of aluminum of steel, can be moved radially to any suitable position. Given the revolutions of the engine, the horseapower can be immediately read off from the curves supplied with the instruments. A correction is given for variation in atmospheric conditions. The instruments are made in four sizes, covering between them a range from 300 to 500 h. p.
L a Natzlre for April 6 , 1918, describes a new form of voltaic cell, with electrodes of zinc and carbon in a soldtion of salammoniac,which is due to Mr. FCry, and has been in use for some time on the French railways. The negative electrode is a plate of zinc which rests on the bottom of the glass containing jar, the copper wire connected to it being insulated up to a point well above the level of the solution in the jar. The positive electrode is a carbon tube of diameter about half that of the jar, pierced with holes, which rests on the zinc plate, being insulated from it by an ebonite cross. The evaporation of the sal-ammoniac sglution is prevented by the wooden cover. During the action of the cell, the lower part of the solution becomes acid, owing to the descent of the dense zinc chloride, while the upper part becomes alkaline, owing to the ammonia produced. The depolarization of the cell is effected by the air alone. The electromotive force of the cell is 1.18volts, and a cell giving go amp. hrs. weighs only 2.1 kg.
SOAP AND GLYCERIN MANUFACTURE IN INDIA
It is understood that the Madras government contemplates shortly opening a soap factory at Hyderabad and that a recent visit of the Director of Industries and Commerce of Hyderabad to Malabar was for the purpose of collecting information and copying the government soapery in Malabar as regards plant, etc. It is believed that the Bombay government will soon establish a soapery and indeed i t is evident that the several provinces are inquiring into the possibilities of the soap business which Sir I?. A. Nicholson has so successfully established and proved to be a sound commercial proposition. More than all this, it is quite probable that the Munitions Board before very long will be running large factories at various centers in India for the manufacture of glycerin. A glycerin industry is well calculated to bring in its wake factories for the manufacture of soaps and candles and altogether the outlook for the oil trade is certainly promising. The west coast, it may be mentioned, is eminently suited for the manufacture of glycerin, since oils of all descriptions are very largely available.
OILSEED INDUSTRY OF RHODESIA
In view of the fact that even before the war it was becoming difficult to cope with the world’s demand for oils and fats for the manufacture of margarine and that this difficulty has been increased during the war, it is interesting to note that the cultivation of oilseeds promises to become an important industry in Rhodesia. At present, ground nuts and sunflower seeds are the only oilseeds produced commercially, but experiments conducted with other oilseeds show that these may be successfully grown. Castor seed, sunflower seed, sesame seed, and linseed grown in Rhodesia have been tested at the Imperial Institute, London, and have given entirely satisfactory results. Before the war sesame seed was chiefly crushed on the continent but this is now being done in the United Kingdom.
