23 2
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
set-up now in use for investigations is the result of two years) continuous development and application. With our laboratory contact tube a great mass of d a t a has been collected in connection with the catalytic oxidation of such reactions as anthracene t o anthraquinone, naphthalene t o phthalic acid and naphthoquinone, benzene t o maleic acid, and toluene t o benzaldehyde and benzoic acid, in addition t o similar reactions of numerous other hydrocarbons and their derivatives. It possesses the distinct advantage of a close approach t o absolute temperature control which is so vital for the duplication of results under fixed conditions and the establishment of reliable data. It is, moreover, simple t o manipulate, which is of importance in problems where a very large number of runs are necessary in order t o accumulate a large mass of data before conclusions can be drawn safely. Advances are moreover being continually recorded toward improvement of design. Of course, a special vaporizer and a different form of condenser must be adopted for each raw material under investigation. The reaction velocity of these partial oxidations appears t o be without doubt much less t h a n in the case of the oxidation of sulfur dioxide t o sulfur trioxide and of ammonia t o nitric oxide in the presence of platinum as a catalyst, and therefore the productive capacity of a converter of equal size is relatively small. This is an important factor in the design of large scale apparacus and coupled with the necessity for rapid heat removal t o maintain a constant temperature, without being cumbrous and impracticable, makes the problem doubly difficuli. Definite progress has been made in our experimental manufacturing plant so t h a t the problem of tempe,ature control has been solved and large scale production now depends on the development of suitable tonnage uses for the products. We are able t o furnish either maleic acid or its isomer, fumaric acid, in sample lots t o those who may have an interest in their utilization. Many such possible uses are evident and are being thoroughly investigated. When you consider the very reactive nature of maleic acid, its anhydride and amide, the possibilities in pure chemical synthesis are unlimited. I t opens up the possibility of the commercial production of many of the straightchain acids such as fumaric, malic, succinic, aspartic, tartaric, propionic, lactic, acrylic, malonic, and hydracrylic acids. The use of these acids t o replace those previously obtainable only from natural sources (mainly fruit juices) is receiving attention and has very decided possibilities. I n conclusion, we wish t o express our sincere thanks t o our Messrs. G. C Bailey, F. A. Canon, A. E. Craver, L. A. Helfrich, W. J. Huff, J. F. W. Schulze, C. G. Stupp, and their some ten t o a dozen assistants engaged on this problem, all of whom have contributed t o the success of the undertaking and have by their earnest effort and teamwork made possible the development of the original discovery t o a completed manufacturing process.
Vol.
12,
NO. 3
THE GENERATION OF HYDROGEN BY THE REACTION BETWEEN FERROSILJCON AND A SOLUTION OF SODIUM HYDROXIDE' By E. R. Weaver BUREAUOF
STINDARDS,
DEPARTMBNT OF
COMMERCE, WASHINGTON,
D.
c.
Received May 16, 1919
D E S C R I P T I O N O F THE F E R R O S I L I C O N P R O C E S S
The generation of hydrogen by the reaction between ferrosilicon and a solution of sodium hydroxide is, in itself, an interesting process which has been, extensively employed in recent years for filling military and naval balloons. The cost of materials makes the method expensive, but i t has several great advantages, especially for use aboard ship and in portable units for field service. A very rapid rate of production of hydrogen can be secured from a comparatively small and inexpensive plant with very little labor and only sufficient power t o operate the water pumps and stirring machinery. None of the materials used are combustible; they do not give off hydrogen until mixed, even when wet; and they are easily and safely transported and handled. T h e principal reaction involved may be represented by the equation: 2NaOH Si HzO = NazSiOs 2H2 (I) This equation probably represents the reaction taking place a t the beginning of a run. However, sodium silicate in solution hydrolyzes, giving sodium hydroxide and hydrated silicic acid as indicated by the equation: NazSi03 (x: 4- I ) H ~ O= zNaOH SiOz.xHZ0 ( 2 ) If we combine Equations I and 2 , we have
+ +
+
+ + Si + (x: + 2)H20 = SiOz.xHzO + 2Hz
(3) While these equations may not represent all the complex compounds occurring in the solution, they probably represent the general course of the reaction, which thus appears t o be in effect one between silicon a n d water, the sodium hydroxide serving as a catalyst. This viewpoint is important, since it shows t h a t t h e relative amounts of alkali and ferrosilicon t o be used in practice should be determined by the speed of reaction and the relative cost of the materials, rather t h a n by computing the proportions corresponding t o a definite equation. T h e plant required for the production of hydrogen consists of three principal parts: ( I ) the solution tank in which the sodium hydroxide is dissolved, ( 2 ) the generator in which the react'on takes place, and (3) the washer, or condenser, in which the evolved gas is washed and cooled with water before being stored or put into the balloon. T h e generator controls should permit the operator t o regulate the supply of sodium hydroxide solution, ferrosilicon, and water. 1 Publisiied by permission of the Director of the Bureau of Standards. This work was done in connection with the use of the process for military purposes. I t was shown that certain changes in the methods used b y at least one of the allied nations would result in greatly facilitating generator operation with a saving of two-thirds of the sodium hydroxide and some of the ferrosilicon The experiments, computations, and results, including specific operating directions for field generators, are given in considerable detail in the Fourth Annual Report of the National Advisory Committee for Aeronautics. This paper is intended only to present the method of investigation employed.
Mar., 1920
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 CHEMISTRY
The operation of the generator is as follows: A predetermined charge of sodium hydroxide and water is stirred in t h e solution t a n k until solution is complete. A part or all of the solution is then run into t h e generator, and ferrosilicon added a t such a rate as will best control the evolution of the gas. The heat of solution of sodium hydroxide is sufficient to start the reaction. The heat of this reaction increases the temperature rapidly, a large amount of water is evaporated, and i t soon becomes necessary both t o cool and dilute the mixture, by means of a cold-water spray within the generator. The process continues until the charge is exhausted.
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