US1138191A - Method of producing ammonia and the like. - Google Patents

Description

J. E. BUCHER.

METHOD OF PRODUCINGAMMONIA AND THE LIKE.

APPLICATION FILED JAN 8.1914.

1, 1 38, 1 91. a Patented May 4, 1915.

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UNITED STATES ATEN 1 JOHN E. BUCHEB, 0F COVENTRY, RHODE ISLAND, ASSIGNOR TO NITROGEN PRODUOTS COMPANY, OF PROVIDENCE, RHODE ISLAND, A CORPORATION OF RHODE ISLAND.

METHOD OF-PRODUCING AMMONIA AND THE LIKE.

Original application filed October 21, 1912, Serial No. 726,924. Divided and this application filed 1914. Serial No. 810,973.

. pounds.

The Process in question is essentially synthetic in character in its preferred form, and was suggested by my work on the synthesis of cyanids and on my processes for purifying: and preparing metals, in which nitrogen plays an important part. Letters Patent for these processes have been granted, the same being numbered and dated 're- December "2. .1913; No. 1,082,8-5; dated December 30, 1913; No. 1,086,019, dated February 3, 19H: and N 0. 1,087,900, dated February 17, 1914-.

One of the equations representing the fumlmuc-ntal ideas of catalysis and reversible reactions upon which ,these four patents are based is the following:

4 (ll "2Na+2C+N +iron=2NaGN |-iron.

The present application is a division of mv application entitled Process tor fixing atmospheric nitrogen, filed October 21, till), Serial Number 126,924, now Patent :'i ljltlhlrli, dat'cd March 24,1914, which re ates to a pro'ccssfor converting carbonates and the like into cyamds, as per equat on:

a N.. 10, 40+N iNtom-imn.

The present divisional application relates this connection that when the source of the' metal anticipating in the reaction is such a compound thereof as,- for example, is sodium carbonate, this compound, as well as the car- Specification of Letters Patent.

Patented May 4, 1915.

January 8,

bon solvent employed,behaves,in efi'ect,catalyt-ically. In the said application, of which this is a division, is to be found a presentation of much of the art relating to cyanid production, and since this art is now of record in the parent application, specific reference thereto, together with considerable of the matter set forth in the parent application relating, to said ai't, or serving: par-' ticularly to point out the essential difi'erences between the known processes and that;

more especially referred to in the parent application have been omitted for brevity.

The hercina l ter described process accordingly aims to economically fix atmospheric nitrogen in such a form, 0. {1. ammonia. that it may be utilized either with or without subsequent operations, according to the nature of the ultimate product sought.

In the acconu'ianying drawings, which form a part hereof and in. which like refer ence characters designate like parts throughout the several views, I have exemplified one spectively as follows INo. 1,079,974, dated form of apparatus in which my process may be eliectuated. It is to be' understood, however, that this apparatus is but one of many adapted to the purpose in question, and that i lions may be made therein without departmgfrom the spirit of my invention. In

general .I ma y state. tliei'etore, that my said invention is to be regarded as limited only by the scope of the appended claims. I

Description, of lI-/I/m!'rnfus.-Refcrripg to the drawing; Figurel is a longitudinal \crlical section of a mullle furnace with rotorts in position therein. Fig.- 2 is an end elevation of said furnace; the blast lamp being omitted for convenience of illustration.

Fig. 3 is a fragmentary section of one of the pipes or retorts, the scctionbeing taken on line III-III of Fig. 1. section of a retort adapted for the use oi air in the. process. I

Brickwork or other suitable material may be employed in the construction of the mufl e 1, and one or more iron pipes 52, servinn as retorts, may extend directly there'- through. v I

(aps or unions 3, serve to connect the ends of the retorts to the plpes 4-5; those Fig. 4 is a similar designated 4- being the pipes for supplying nitrogen or air as the. case may be.

he; gases, notably carbon monoxid, evolved during the operation of the process are conveyed away via pipes 5.

' A blast lamp 6 or other suitable source of heat may be disposed in the preferably open end of the mufile and this apparatus should, of course, be capable of heating the retorts up to. the reaction temperature employed; which will be hereinafter very fully dis- If the process is to be conducted in such fashionas to :permit the use of air, rather thanfree nitrogen (which latter is, however,

= preferred where the process is so conducted us to yield ammonia directly in the manner hereinafter described), the .air is led in through pipes 4 and preferably first encounters one or more masses? of charcoal :or other suitable oxygen consuming material. These masses preferably substantially fill the pipes at the points where they are disposed .so that all of the air is obliged to pass therethrough. I prefer in such case to inter-pose wire gauze spacing or supporting screens '8, or] the .like, between the charcoal and. the body of the reaction mixture 9 which is next encountered by the gases flowing through the pipe or retort; since it is desirable to keep the charcoal away from the charge. If nitrogen .be' supplied as such,

. rather than mixed with oxygen in the form inexpensive source,'of the metalforming the base of the cyanogen compound to be incidently formeddurin'gr the operation.

Theory of operation. ,In chemical work,

it"is often necessaryto dissolve solids to make them reactive; and we also know that when substances a re dissolved they very .fr'equntly become dissociated. These and many-similar.considerations point tov the conclusion that if the very complex and ordinarily comparatively inert carbon can thus be dissolved it will not only acquire mobility but perhaps may also become less complex; thus'approaching the nascent condition.

' Ironis one of the best solvents known for carbon. Hence a solid solution. such as is obtained in the cementation process of manufacturing stcel, \\71ll form very quickly at the surface of tlie meta l; provided that it is not already there, as in carburizediron. The conditions at this surface should be exceedingly favorable for chemical reactions and the above mentioned results obtained by the use of finely divided iron are in accordance with this view. Presumably a part atleast of the opera tion takes place as follows: the small quantity of sodium vapor, formed according to equation 3, and thenitrogen come in contact with the reactive surface of the carburized' iron where they combine very quickly with the carbon dissolved in the surface of the iron, forming sodium cyanid. The vapor pressure of the gaseous sodium, is thus reduced and consequently another portion of sodium carbonate decomposes to reestablish the equilibrium. -This new portion of sodium vapor in tu n combines with nitrogen and carbon at the surface of the iron, which has meanwhile become recarburized by taking up carbon from the carbonaceous masses in contact therewith, or from the carbon in solution in the mass of iron. The iron hence acts as a catalyzer'by undergoing a series of decarburizations and recarburiza tions; resulting in the eflicient and continuous production-of reactive carbon for the process. The very quick combination of sodium at this catalytic surface reduces the concentration of the sodium vapor steadily; and this materially aids in producing a continuous liberation of sodium with the consequent continuous formation of'sodium cyanid. This'very simple theory, enables us to deal intelligently with the many conditions which influence the process. Evidently the first requisite is to produce as efficient a catalytic or solution surface as practicable and to maintain its efficiency during the process;

' Even when the conditions of surface and 'contactappear to be correct or nearly so, at times a lapse of 10 or 15 minutes may occur before any vigorous reaction takes place. This may be due, insome cases, especially when working at a relativelylow temperature, to the time consumed in carburizing the reactive surfaces of the catalytic material; and probably also to changes in the relative disposition of fiuid and solid constituents of the reactive mass by, for example, capillary action. The theory of the operation must therefore be borne in mind while the actual procedure really a compromise between various factors. At one temperature one factor becomes dominant; at another temperature sometimes quite close to the first, another factor gains the ascendency, and so on. v y

Should my theory be faulty, which however I do not think is the case, it at any rate supplies a working hypothesis which vii-- ables us to achieve consistent and successful results.

Sources and condition, 0' catch 201', etc. A fine state of division 0 the iron exposes a large surface and hence acts favorably. Similarly a line state of division of the carbon favors the quick carburization of. the iron by providing thorough contact at, what Imay term, the solution surfaces, or as l refer to term it in the aggregate-surface.

The catalytic agent, 2. g. iron, if used in solid form should be quite finely powdered or in such other form as to expose, or to render possible the exposure of, a relatively enormous solution surface. Particularly is I this the case when the operation is conducted at temperatures materially below the eutectic point ofthe carbon-containing material. If the iron be a coarse powder, insufficient surface will usually be provided, under such, conditions, to permit of the process beingconducted efficiently. If, on

the other hand, it is too. finely divided, there is some tendency to pack too tightly and thereby prevent diffusion of th gases and vapors involved. On the who e, however, I prefer to divide the iron as finely as possible and to provide forl diifusion in some suitable manner such as will be hereinafter indicated.

When theparticles of catalytic material are relatively large, the surface is correspondingly-small and the area of contact is likely to be too small for quick and efiicient renewal of the. carbon content in thelcatalytic surface. Uuder the indicated conditions which I have found convenient in effectuating my process, when nitrogen and relatively fine and the graphite comparatively coarse, than when the relative sizes were reversed, i. e. when the iron was coarse and the graphite was fine. Thus iron Ph. G. IV. which is far finer than 100 mesh,

gafve very good results when: used with graphite which had been passed through a one 'hundred mesh sieve but which on the whole 3. as not nearly so finely divided as the iron. An even b tter result was obtained when said'fine iron was used with graphite tinct maximum for the graphite of inter-' of 60 to mesh. When, however, the

aphite was of 20 mesh, used: with this very iie iron the action was considerably slower. This series of tests, show, therefore, a dissodium vapor cannot so easilypenctrate the interior of the mass whereby to ethnically contact with the reactive surfaces (or as I herein boardly term it, reactive surface).

On the other hand, when the graphite particles are too coarse the fine heavy particles or iron will tend to drop through the interstices and thus become segregated. The latter action would, in extreme cases, beequivalent to removing the catalyzer from the field of action. I find that either of these two extremes may substantially result in the failure to produce cyanid. f

It is to be understood that while Iregard finely divided iron. as generally preferable for use in the process, in view of the possibility of increasing the potency of certain other factors hereinafter referred to, I do not wish to be limited to any particular .size, condition or source of the catalyzer or indeed of the size, condition or source ofcarhon for the same. For example, pulverulent iron may be produced directly in the react ing mass itself from iron compounds or ores, such as oxids, carbonates, and the like, 6. (1., hematite, magnetite, siderite'and iron scale. A mixtu're'of finely powdered hematite, carbon and'sodium. carbonate may be pre pared in such proportions as to leave the 1ron, graphite and sodium carbonate'ni favorable proportions for cyanid synthesis after the excess of graphite had reduced. the hematite to metallic iron with the evolution of carbon monoxid. Under these circumstances the iron becomes reduced very readily (even if the solid carbon particleslshoilld not come in thorough contactaviththeiron ore, reduction would still take place completely because the molten cyanicl formed reduces iron oxide with the utmost case and even carburizes the iron at the same time). Further, if the temperature be suificiently high, sodium vapor will be formed, which, of course, will act as a. powerful reducing agent.

(arbour-The carbon may be supplied from a variety of suitable. sources and in addition to those mentioned, which are solids, carbon supplying vaporsinay be used. Thus the hydro-carbons, e. g). petroleum, are available for use in certain cases. highly desirable usually to substantially completely exclude the oxygen of the atmosphere from participation in the reaction resulting in the production of. cyanid, since oxygen either converts thccyanid formed to cyanate; or oxidizes the iron and results in the production of ferro-cyanids or the-like upon subsequent lixiviation; or even worse, it may destroy the cyamd fornicthwith reproduction of carbonate. The carbonhas greater freedom of motion than one ni ghtat first expect. Its diffusion is not limited to u'ierhanical motion due. to the actionof gravity, agitation of the mass, melting'of its It is solid material with consequent sintcring, .washin effect on the particles by currents of liquid us to surface tension, change of concentration, ca illai'ity, distillation of liquids etc. It is solu 1c in the iron, or the like, use

. as a catalyzer, and can diifuse either in the form" of solid or liquid solution. It may, in effect, be'ca'rried as liquid, vapor, or even as solid in the form of sublimate, by compounds such as cyanide, e. g. sodium cyanid. If these compounds come in contact with iron lacking in carbon, a reverse action may take place, thus helpin to carburize the mass of iron. Indeed, t is imparts a mobility to the carbon such as would be attained if'the carbon could difluse as a vapor, thus giving to the carbon, such as graphite, coke, charcoal, etc., in the tube, essentially the same kind of freedom that it would have if used in the form of hydro-carbons.

, All-alt metaZ.'The source of alkali metal 'or other base of the. cyanogen compound formed during the course ofgthe process, is preferably some. inexpensive compound such as sodium carbonate,'sodium bicarbonute, sodiumhydrate, or the like, but it is possibleto employ initiall free alkali metal or its equivalent, and int ose of the claims herein set forth which are of suflicient sec 0' to be readable upon'a process using initial fi' free alkali metal or its equivalent as We as upon alkali metal other than initially free (in other words, where the alkali metal, or a volatile compound thereof, is supplied from a source of the same,' relatively remote from the-reaction zone) are not to be deemed as being limited to such supply of alkali metal, or the like, froman existing compound ofxthe same,

With respect to sodiumbicarbonate I per.- ticularl desire to call attention 'to thejfact that I ave successfullyjused the moist bicarbonate which comes from ,the ammonia soda process;v and this without previous drying: Indeed, very many impure alkali compounds which may result from various technical processes can be converted into pure cyanogen compounds. For example, mixtures of alkali hydroxids, carbonates, acid carbonates, acetates, oxalates, etc., can be used directly if -ir on, oxids, or hydroxids or organic salts of iron,'c arbon or organic mat-- ter in eneral be present; and no contamination of the alkali cyanide can occur since the substances of.-.the classes mentioned are so transformed in the process that the only 1 negative radicle remaining will be cyanogen. If more than one alkali m hal be present,

however, a mixture of alkali .yanE .ls will result. When the cyanid obtained is to be transformed into ammonia as hereinafter 'described almost any other impurities may be present without affecting the purity of the product, providing suitable precautions are taken. It is obvlous too thatsodium' car- 7 ferred to.

-ferred to, that. for the production of cyamds, the nitrogen is derived from coal more or-less directly presenting the reactive solution exert an enormous influence when we consider its various effects. It increases the velocities of chemical reactions enormously,

and it also increases the rate at whichthof carbon goes into solution in the iron; as well as the rates of gaseous dillusion and de. velopment of vapors. The temperatures of the operation further intimately concerns the surface and contactconditions above re- 1 further do not wish to be restricted to any particular lower temperature limit, and indeed I contemplate effecting the process in certain cases at temperatures below even 700 (3., since rubidium and caesium carbonates, for example, and especially mixtures of these'or of one or more of: these with sodium or potassium carbonate or analogously acting compounds permit of materially lowering the temperature at which the nitrogen fixing reaction takes place (principally, I believe, by increasing the fluidcirculation) H By incorporating cyanids initially in the reaction mixture, the same end may. also be attained in a measure.

I desire in the present divisionof my said parent application to point out more particularly the utilization of certain of the steps of my eneral process in forming ammonia or the like substantially by a direct reaction.

-'Dr. Ewan states in his article in Thorps Dictionary of Applied Chemistry, above rein every process now used This is equivalent to saying that the cyanids are, in general, prepared from ammonia. In contrast to this, one of the main objects of the present invention is the commercial production of ammonia through the instrumentality of cyanide produced from atmospheric nitrogen; thus making the production of ammonia independent of the use of initially combined nitrogen. Indeed, as intimated above, I contemplate effecting, in some cases, the production of ammonia in such a mannor that the cyanid formation will be but momentary or evanescent, so that. in efiect.

the ammonia may be produced 'not'onl syn thetically but practically directly. This last can probably best be referred to while con sidering the phase of the process which involves the formation of cyanid as a definite and intermediate step.

'A1mnom'a.-Assuming that the apparatus shown by way exemplification has been charged with iron, carbon and a preferabl inexpensive alkali compound, all in suitab e form or condition and properly disposed with respect to each other to yield alkali through it. -.\mmonia will be produced ac-- cording to the following equation.

\Ve show that '0 have here a cyclic process for producing: ammonia from air and water through the instrumentality of car bon l alternately passing nitrogen or steam through a mixture consistimg of iron, carbon and, for example. sodium carlmnatc.

If desired, the carbon monoxid and hydrogen may be burned with air, thus producing heat, which may be utilized in the process, and -a.mixture of carbon dioxid, hliilOflQfl and water. The water condenses and the carbon dioxid and nitrogen together. with the ammonia already formed may be passed into a solution of sodium chlorid, as in the ammonia-soda process. The carbon dioxid of the mixture is thus ultimately utilized to form sodium bicarbonate, or sodium carbonate. leavingthe nitrogen in a fairly pure form for use in the preparation of another portion of cyanid according, to equation l.

The process is admirably adapted for use with the ammonia-soda process as it may utilize the waste atmospheric nitrogen from this process to furnish the pure ammonia, required in the latter process, very cheaply. The expense of the ammonia as well as the troubles arising from the impurities liable to be contained in commercial ammonia are at present seriou obstacles to the economical operation of the ammonia-soda process; but both of these ditliculties are obviated it'. ,lny process is used in er'mnect-iou therewith.

The sodium carbonate acts cyclically to fix nitrogen by being transformed into cyanid and then the cyanid is changed back into carbomite, (equation 3), by the use of steam. If desired, we may start with the cyanid instead of the carbonatc,in thiscycle. For example, a mixture of potassium cyanid, carbon and iron may be heated in a current of steam until a substantially quantitative yield of ammonia 's obtained. The steam is then displaced by a current of nitrogen and the temperature is raised to about 1100 C. In a short time the action will be completed and the retort will be found to contain much cyanid; the potassium carbonate ha ring again been transformed into cyanid.

Upon adding carbon as required, the proc- T' ess may be repeated over and over again as the cyanid or carbonate acts cyclically while the iron acts catalytically. The temperature should not be too high, otherwise too much oxidation results from the steam and there is more tendency for cyanogen compounds to pass over with the ammonia.

\Vhen the temperature is at lequate but not excessive. very little of the cyanruzen compoumls will pass over with the ammonia, and even these can be recovered very easily by using suitable scrubbers. If desired, thc ammonia may be obtained from the scrubbers in anhydrous form.

My present invention contemplates the production of ammonia in such manner that the cyanid formation will be transitory or evanescent. To so etl'ectuate the process it is merely necessary to reduce the temperag ture of the operation to a point (approximately 725 C.) where while the cyanid forming reaction is proceeding, the reaction shown in equation 3 may also occur. Under such conditions the catalytic material, iron, previously considered. is supplemented by the alkali metal carbonate which now may be regarded as an auxiliary catalyzer. The equation. may be represented thus: i

(l) Nfi-lC-i-HLO-lsodium carbonate+i ron In this case one of the cat-alyzers (e. iron) pnobably acts passively or merely as a solvent for one of the actively pai'ticipat-' ing, elements; while the second or auxiliary catalyzer is itself actively involved in the reaction. The cyanid is prolmbly intermediately produced, and in effect simultaneously \vith the'ammonia. If desired, however. the production of ammonia may be effected at the same or a slightly higher temperature. let us say for example, 750 C., by passing the nitrogen current until a proper cyanid formation has been effected, then substituting steam for the nitrogen current. thereafter alternating the nitrogen and steam, thus also in effect using the alkali carbonate as a catalyz'er, the temperature being maintained substantially constant. it desired.

General rewmrks.-()\ving to the numerous possibilities of the process. have only described some of the more important steps involved, hence I wish to be limited only by the general spirit of the above disclosures and by the appended claims.

For convenience, I have described most of the operations, and written the corresponding equations, for sodium compounds; but these descriptions are intended to apply to alkalicompounds generally. and. where applicable, to metals capable of performing like functions in the process.

Having thus described my invention what I claim is: Y

1. The process of fixing nitrogen which comprises brin 'ng initially free nitrogen into contact wit carbon dissolved in a mass I ofcatalytic material presenting an extended mately 725 -C.,

carbon with-said nitrogen-as cyanogen and so i 2. The process of fixing nitrogen which comprises bringing initially free nitrogen into contact with carbon dissolved in a mass- =0f catalytic material presenting an extended solution surface, and heated to approxicombining the dissolved reacting upon the latter substantially directl as formed with a, substance capable of yielding the element hydrogen, whereby to combine said nitrogen w th; said hydrogen. i

3. The process of fixin nitrogen which comprises bringing initia ly free nitrogen into contact with carbon dissolved in a mass of catalytic material. presenting an extended solution surface, combining the dissolved.

carbon with said nitrogen as cyanogen and reacting upon the latter substantially directl as formed with a substance capable of yiel, ing the element hydrogen, whereby to combine said nitrogen with said hydrogen. 4. The process of fixing nitrogen which comprises causing successive reactions in the immediate vicinity ofa mass of metal containing dissolved carbon, to, first evanescently combine said, dissolved carbon with free nitrogen and to then immediately recombine said nitrogen with hydrogen, by

contacting free nitrogen molecules with carbondissolved in said metal, and simultanei ouslyicontacting said molecules with those of a compound the base of which is adapted to act asthe base of a cyanogen compound and immediately reacting upon the resultant product with a substance capable of yield- 1 mg hydrogen, said first mentioned compound aud said metal acting catalyticall 5. The process of fixing nitrogen w ich comprises causing successive reactions in the immediate vicinity of a mass'of metal containing dissolved carbon, to combine said dissolved carbon with free nitrogen and to gen, by contactin free nitrogen molecules with carbon-disso ved in said metal and si- '60 then recombine said nitrogen with hydro-' multaneously contacting said molecules with those 'of a compound the base of which is adapted to act asythe base of a cyanogen compound, and reacting upon the resultant product with a substance capable of yieiging hydrogen, said first mentioned co pound and said metal acting catalytically.

6. The process of fixing nitro enwhich comprises preparing a mixture 0 a pluralof analogous compounds the base of each it of which is adapted to act as the base of a cyanogen compound, said mixture having a.

melting point materially below that of any.

of its constituent compounds, subjecting said mixture to heat, to melt the same, and to the action of carbon, dissolved in material,

capable of rendering said carbon reactive, and further to contact with free nitrogen and a substance capable-of supplying hydrogen to the resultant compounds formed by reactions which may be effected between said reactive carbon, n trogen andisaid first .nientioned com ounds, and thereby effect ing two sets 0 reactions in se uence, the first of which. yields said resu tant compounds'and the second of which unites the nitrogen thereof with hydrogen. I

In testimony whereof I have aifixed my signature, in the presence of two witnesses. JOHN E, BUCHER. Witnesses: NORMAN E. Hour,

THOMAS H. ROBERTS.

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