US1697105A

US1697105A - Manufacture of oxidation products of hydrocarbons

Info

Publication number: US1697105A
Application number: US656085A
Authority: US
Inventors: Francis J Carman
Original assignee: Individual
Current assignee: Individual
Priority date: 1923-08-06
Filing date: 1923-08-06
Publication date: 1929-01-01
Anticipated expiration: 1946-01-01

Description

Jari. 1, 1929.

F. J. CARMAN MANUFACTURE 0F OXIDATION PRoDUc'rfs 0F HYDRocARBoNs Filed Aug. e, 1925 *0369i 0500@ USM 5% 95:50,@

Fra/wals J O'wrman PSW "a atl'ozuwql Patented Jan. l, 1929.

,UNITED STATES FRANCIS J'. CARMAN, OF NEW YORK, N. Y.

MANUFACTUBE OF OXIDATION PRODTJ'C'IS OE HYDROCABBONS.

Application iled August 6,1923. Serial No. 656,085.

This invention relates Ito manufacture of l,oxidation products of hydrocarbons; and it relates more articularly to processes in which hydrocarl; the halogen `derivatives oxidized, most advantageously with the aid of suitable catalysts, but not necessarily so, under conditions favoring production of fthe desired oxidation products from the hydrocarbons. More specifically, the invention relates .to

the manufacture of aldehydes, and particularly formaldehyde, by processes of this general character.

The principles of the invention are be- A lieved applicable to limited oxidation of hydrocarbons generall and in its broader aspects the invention 1s therefore to be viewed as not restricted to the treatment of any specific class or series of hydrocarbons. Its

greatest present utility is in themanufacture of aldehydes from aliphatic hydrocarbons, particularly the paraiiin series of hydrocarbons, and specifically in the manufacture of formaldehyde from methane. Accordingly the manufacture of formaldehyde from methane will be more particularly hereinafter referred to and described as an illustrative example by means o'f which a full understanding of the principles underlying the invention ma be afforded'.

It is to be understoo however, that other hydrocarbons, not necessarily aliphatic but characterized by the presence ofone or more paraffin radicals or groups in the molecule, are susceptible of treatment in accordance with the invention to produce useful prodplet of limited oxidation, especially aldey es.

Attempts have been made heretofore to produce intermediate oxidation products of the paraffin or saturated hydrocarbons by reacting directly thereupon with oxygen, but the diiiiculty is that oxygen does not react with them except at, temperatures where it also reacts too vigorously with the desired final products for any appreciable yields of the latter to be recovered. Thus it is that, in the manufacture of formaldehyde, for ex-` ample, present commercial methods are of 5o quite a different type not involving the use Y of methane itself. Y

'It is a principal object of the present invention to enable intermediate oxidation products of hydrocarbons to be obtained by oxidizing'said hydrocarbons under such conditions as to render the oxidation suscepti-4 ons are halogenated' andble of regulation and control, whereby the desired oxidation products are recoverable in substantial quantities, thus making possible the commercial production of intermediate oxidation products. of the character described, using thc parent hydrocarbons themselves as starting material, and thus avoiding the use of more costly derivatives which must be 'relied upon as starting material in processes heretofore known. A further and more specific object of the invention is to enable for'maldehyde to be-manufactured directly from methane or lgaseousI mixtures, such as natural gas, containing` methane. A

With the foregoing objects 1n view, as

well as others which will become apparent as the disclosure proceeds, the invention comprises the novel process and process steps hereinafter disclosed and explained in connection with a specific' illustrative example to which, however, it is to be understood the invention in its broader aspects is not restricted. l

Y Generally described, the process of the invention comprises a carefully controlled and regulated oxidation of hydrocarbons, inthe course of which oxidation the hydrocarbons pass through, or may be considered-tol pass through, a transition stage in which they exist in halogenated form as the result of what may be termed' an initial oxidation. Further oxidation results in splitting off the corresponding hydrogen halid and producing the ldesired intermediate oxidation product of the particular hydrocarbon in question; while oxidation of the hydrogen halid regenerates the halogen which can be used,

to halogenate more of the hydrocarbon and thus maintain a cyclical process. In the case of manufacturing formaldehydefrom methane, and assummg that the halogenating agent employed is chlorine, be represented, for purposes ofexplanation, by .the following reactions:

Within the scopeA of the invention as viewed in its broader aspects, these reactions maybe carried out: separately and in the order indicated, But it is'of great advantage in practice to carry out all three reactions simultaneously or substantially so, especially when this is clone 'th the aid of the process may a catal st as will be more fully hereinafter pointe out. Itis to be understood that 1n speaking of carrying out these reactions simultaneously, it is not intended to assert that the chemical action as it actually occurs necessarily follows the precise reactions here given, these merely representing in a convenient manner one way of explaining what takes place. The exact mechanism of the chemical reactions occurring when the process is carried out in practically one stage, instead of in the three stages represented by the above explanatory reactions, may be more or less complex and cannot readily be determined with certainty. Furthermore the reactions by which the intermediate oxidation product is obtained are in practice accompanied to` a greater or less extent by side-reactions such as further chlorination to polychlor-derivatives, and oxidation of these and of formaldehyde and other oxygen derivatives to carbon monoxid, carbon dioxid and Water.

By proceeding in accordance with the invention as ,v generally set forth above, the

desired `oxidationof the hydrocarbon starting material may be effected at relatively low temperatures and is susceptible of reasonably accurate control and regulation; with the result that it is possible to produce and recover substantial yields of the desired intermediate oxidation products from the reaction gases. o

The initial oxidation of the hydrocarbon by halogenation can be effected quickly and i quantitatively at comparatively low temperatures, the extent of the halogenation depending upon the relative concentrations of the gases, the action of light, and the presence or absence of catalysts, as well as Aon the temperature. The symmetry of the Vhydrocarbon molecule having once been broken, the resulting compounds are then much more readily susceptible to the action of oxygen. Accordingly, by initiating the ,A

oxidation ofthe hydrocarbon through chlovrination,`for example, and then treating the resulting chlorine derivative with oxygen to produce the desired oxygen derivative, such oxygen derivative can be obtained from the hydrocarbon Without at any time exceeding relatively low .operating temperatures, thus permitting recovery of good yields of said oxygen derivative. The hydrogen chlorid split olf in oxidizing the chlorine derivative may'be wholly o'r largely oxidized to regenerate chlorine for re-use in chlorinating more of the hydrocarbon. By causing these .severa1 operations to occur simultaneously,y a certam proportion of chlorine will therefore su'ice for the resultant oxidation of more Aof the hydrocarbon than corres nds tothe proportion of the primary-ch orine. derivative consumed. l

' A concrete example illustrating'how the process of the invention may be applied to the manufacture of formaldehyde `from methane will now be given, reference being also made to the accompanying drawing which represents more o r less diagrammatically a system of apparatus suitable for use in carrying out the process. Gases resulting from a previous operation, contained in gasometer 1l, are mixed with fresh gases in mixing chamber' l, namely, methane, chlorine and oxygen, said fresh gases being introduced through the correspondingly designated valve-controlled pipes as shown 0n the drawing. In the mixing chamber l, the gaseous (i. e. gaseous or vaporous) mixture is preheated to a requisite temperature gases are then scrubbed with 4water in an absorption tower 5, filled with coke or other suitable material. The water from tower `5 collecting in receiver 6, together with the condensate collecting in receiver 4, is worked up for its formaldehyde and hydrochloric acid content. vThe gases leaving the top of tower 5 are conducted into another tower 7 where they are dried by means of concentrated sulphuric acid or other suitable drying agent. The dried gases then pass into a reaction chamber 8 containing a catalyst for oxidizing any earbon monoxid to dioxid, suitable catalysts for this purpose being cobalt sesquioxid or mixtures of copper and manganese oxids. fter passing through reaction chamber 8, the gases are next conducted to and through another absorption tower 9 Where they are exposed to milk of lime, or sodium or potassium carbonate, to remove the carbon dioxid content. A suction blower 10 pulls the residu al gases from this tower 9 and directs them to gasometer 11 from which they are led back as needed to mixing chamber 1., thus completing the circuit.

It is to be understood that the application of legends to the'drawings is not/intended to be in any sense restrictive, but is made only for the purpose of renderingl still clearer the specific embodiment of the invention chosen to illustrate the broad principles involved.

The oxygen employed may-be either. the pure gas or air, or mixtures of these in any suitable proportions; but it is advantageous to use pure oxygen because, among other things,this obviates the necessity for hanfio dling large volumes lof inert gases. It is also to bey understood that the methane or other hydrocarbon employed may be either the pure gas or may be accompanied by other hydrocarbons. Natural gas may be used to furnish methane for the process. Instead of introducing free chlorine into the mixing chamber, hydrogen chlorid may be introduced, it being only necessary to provide chlorine in available orV reactive form, under the conditions of operation.

While it has been greater percentage conversion of methane to formaldehyde is possible in the present process than has been obtained heretofore by the action of oxygen alone, yet even in the present process there is a practical limit beyond which the proportion of gas entering into reaction may .not be profitably ushed, for in higher concentrations a point of equilibrium is reached Where the formaldehyde xdecomposes as fast as it is formed. For this reason itis of great advantage practically to carry out the reactions cyclically as described, and to subject to the action of the catalyst a second time the gases thatv previously passed through unchanged, removing the products of oxidation by absorption in suitable media and making up the losses by additions of .fresh gases.

A variety of different catalysts 'are available for use in carrying out the process of the invention, where a catalyst is necessary ordesirable, as is usually the case. In general, metallicv oxids or halids are suitable; but some that are good catalysts for the conversion of methyl chlorid into formaldehyde are less effective in the'oxidation of hydrogen chlorid or are apt to cause too energetic oxidation of formaldehyde. More stable or fixed chlorids 4are distinctly better catalysts in the present process, especially the fixed halids of divalent metals of the alkaline earth group. The chlorids of calcium, barium and strontium are particularly effective catalysts for the `purposes present invention, and of these, barium chlorid is ordinarily most satisfactory. The alkaline earth metal chlorids are most effective as catalysts in the present process when the temperature and reaction chamber is maintained at from 400. to 500 C; vAt

such temperatures they are very effective in aiding conversion of methyl chlorid into formaldehyde in the presence o f oxygen and methane, and at-the same time they assist in the oxidation of most of the hydrogen chlorid to chlorine which is at once absorbed by the Lmethane present to form methyl chlorid. As between the oxids and the chlorids, the chlorids afford some advantage in that they have less tendency than the oxids to cause destructivedecomposition of the desired hydrocarbon oxidation product sought. Generally speaking,

found Jthat a much- 4be the oxid.

4tice. of the invention,

of the non-volathe invention is to be understood as signify-- ing that compound of a divalent element For the purposes of the present used as a catalyst Which' results from conv tinued action of the reacting gases at the reacting temperature upon the oxid of said element. In the case of barium, calcium or strontium, pound Will be the chlorid under the particular reacting conditions hereinafter set forth; While with beryllium or magnesium it will Any Well known or suitable Way may be resorted to for bringing a large surface of the-catalyst into contact With the gas mixtures, such as deposition upon asbestos, pumice or other porous material,

Whether 1t is a catalyst Vor not;y for in this process, as Well as others employing catalysts, the effective catalytic activity of. any ofthe materials used depends in large measure upon the ext-ent of the surface exposed to the gases.

As already pointed outa it is not advisable from an economic standpoint to attempt to push the percentage conversion of the methyl chlorid 'into formaldehyde too farf in a single passage of the gaseous mixture in contact with the catalyst. In the practherefore, it -is best to operate at what may be determined to be the most economical conversion rate and to re-pass the mixture repeatedly in contact with the lcatalyst in the reaction chamber cyclically, the gases traveling in a circuit. In thus operating, the lresultant formaldehyde is removed fromthe reaction gases Water; residual after each pass, aswell as at a later point hydrogen chlorid, etc.; and

in the c1rcu1t fresh methane, chlorine and'4 oxygen are introduced in such quantities as maybe necessary to restore substantially the original proportions of the gases in the mixture passed over the `catalyst, 'and to for example, such resultant commaintain the production' lof formaldehyde',l

reasonably constant. ver met aneunder the conditions herein set forth to4 form methyl chlorid, the gaseous mixture supplied to the reaction chamber 2 can be considered for all practical purposes to consist of methyl chlorid, methane and oxygen As chlorine ycombines .y readily and quantitatively with the in predetern'xined proportions. There should be a large excess of methane in order that I the chlorine regenerated by oxidation of the hydrogen chlorid split off from the methyl 5 chlorid may immediately re-combine with more methane to form methylfchloridn Accordingly, in a ractical embodiment of the novel process w ich has given good results, the proportions ofthe gases in the mixture supplied to the catalytic reaction chamber are so adjustedy by regulating the. feed of fresh gases that the mixture consists of four parts of methane, one part'. of oxygen, and one part of methyl chlorid or its equivalent in methane and available chlorine, all parts being by volume.A Passing this mixture over powdered barium chlorid at about 480o C., and allowing the mixture to contact with the e. catalyst for a sufficient time, say for 5 seconds or thereabouts by Way of example, converts in-one passage between 8 and 10 per cent of the methyl chlorid to formaldehyde, Whlle at the same time to a somewhat larger proportion of the methyl chlorid is oxidized to carbon monoxid and carbon dioxid. Concomitantly the hydrogen chlorid liberated by oxidation of the methyl chlorid is oxidized to chlorine which, combining with the excess of methane present, regenerates e :50 methyl chlorid. .In 'normal practical Worklng of the process under the conditions as-l sumed in this specific example', all of the hydrogen chlorid is oxidized with the exception of an amount equal to about 0.85

per cent of the methyl chlorid'content of the gaseous mixture su plied to the reac- -vtion chamber; so that tiie loss `of available chlorine in each pass is comparatively slight even if the hydrochloric acid collected with 40 the formaldehyde removedfrom the effluent gases be allowed to waste. After the described catalytic oxidation of carbon monoxid to carbon dioxid, if this be necessary, and the removal of the carbon dioxid, the gaseous mixture sent by the blower 10 back to the reaction chamber by way of the gasometer 11 therefore still consists lof methane, oxygen and methyl'chlorid but in proportions differing from those of Y l5o the original mixture due to the oxidizing `L.reaction and the small loss of chlorine as hydrochloric acid. By `properly adjusting the feed of fresh methane, oxygen andchlorine into' thesystem, in advance ofthe 5 5 mixing and reaction chambers, the original proportions of the gases may be approxi-v mately restored and, the other conditions of operation being maintained uniform, the output of formaldehyde can be kept 'substantially constant at therate found to be fthe best for profitable operation of the 4process.

The isolation of the formaldehyde which is condensed and absorbed, together with 05 water'and hydrochloric acid, from the cir- `tate may be dehydrated with concentrated temperature, addin salt as may beneces sary to lower the freezing point of the fluid to a point at which the olymerization and precipitation is rapid. f it is found desirable to recover the hydrochloric acid present in the aforesaid condensate, l the filtrate from the polymerized formaldehyde precipisulfuricacid and the hydrogen chlorid reintroduced into the circulating gases. Under ordinary commercial conditions, however, the relatively small proportion (e. g. 10%) of hydrogen chlorid escaping re-conversion to methyl chlorid in the .normal operation of the process in its morev efficient forms can be otherwise more economically replaced.

Other halids such as the iodid or bromid maybe used instead of, orin conjunction with, methyl chlorid; but experience thus far has shown the chlorid to be far the most advantageous and its use is therefore to be recommended in practice.` e

In the treatment of more complex hydrocarbons than methane, the production and recovery of any single intermediate oxida- -tionv product is sometimes rendered more diliicult vby reason of the possibility of halogen substitution indifferentA positions in the molecule, thus rendering the production of mixtures of oxidation products likely. This is of course unobjectionable where the production of a sin le oxidation product 1s not essential. In t e case of homologues closeto methane, the liability to production of mixtures ofv oxidation products is not so pronounced and it is feasible, for example,

to prepare acetaldehyde from ethane by the presentv process. What I claim is:

1. Inthemanufacture of partial oxidation products of hydrocarbons, the' process which comprises heatinga gaseous mixture of a hydrocarbon, available oxygen and an available halogen in a suitable reaction chamber to temperatures favoring limlted oxidation# of the hydrocarbon, and separating a desired -oxidation product of said hydrocarbon from the' reaction gases leaving. said chamber, 'at least` a substantial. portion of said halogen being made availablein the t oxidation and again used for. reaction with further quantities of said hydrocarbon.

- 2. rlhe process set forth in claim 1, further characterized by the employment inthe reaction chamber of a catalyst favoring oxida tion under the'condition's prevailing'in said chamber. t y

3. In the manufacture of aldehydes, the d process' which comprises halogenating a hydrocarbon to obtain4 a mono-halogen derivative thereof, and oxidizingA the resultant mono-halogen derivative to obtain the desired aldehyde.

4. In the manufacture of aliphatic aldehydes, the process which comprises halogenating an aliphatic hydrocarbon to obtain a mono-halogen derivative thereof, and oxidizing the resultant mono-halogen deriva tive to obtain the desired aldehy-de.

5. In the manufacture of formaldehyde,

the process Which comprises halogenating methane to obtain methyl halide and oxidizing resultant methyl .halide to formaldehyde.

6. In the manufacture of formaldehyde, the process which comprises chlorinating methane to methyl chlorid and oxidizing such methyl chlorid to formaldehyde.

7. In the lmanufacture. of formaldehyde, the process which comprises halogenating methane to obtain methyl halide and oxidizing resultant methyl halid to formaldehyde in the presence of a'catalyst favoring concomitant oxidation of resultant hydrogen halid and liberation ofthe halogen.

8. In the manufacture nof formaldehyde, the process'` which comprises halogenating methane, oxidizing resultant methyl halid to formaldehyde, and oxidizing resultant hyldrogen halid torender the halogenavailab e, stantiallysimultaneously in the presence of a catalyst comprising a reaction-promoting compound of a divalent element, removing formaldehyde, and utilizing the resultant available halogento halogenate more methane.

9. In the manufacture of formaldehyde,-

the process which. comprises heating to a. reacting temperature a gaseous mixture com'- prising methyl halid, methane r`and oxygen,

and recovering formaldehyde from theresultant reaction gases.

10. In the manufacture of formaldehyde, the process which comprises heating to a gaseous mixture camprising methyl chlorid methane and oxygen, and recovering formal sultant reaction gases.

11. In the manufacture. of formaldehyde, the process which comprises heating to a reacting temperature a gaseous mixture comprising methane, methylhalid and oxygen, in the presence of a catalyzer for the oxida. tion of hydrogen halid, separating re. sultant formaldehyde, adding more methane and oxygen to the residual mixtureof gases, and repeatin f thefheating operation and the separation o formaldehyde, cyclically.

12'. In the manufacture of rformal ehyde, the process which comprises heating to a reacting temperature a gaseous mixture comtion products of hydrocarbons, the process prising methane, methyl chlorid and oxygen all these" reactions being effected sub,

dehyde from the re-v i which comprises in the presence of a catalytic com ound of an alkaline earth metal, said met ane being present in larger volume than either of the other gases, separating resultant formaldehyde from the reaction gases, and re-treating the residual gases for production of more formaldeh de.

13. In t e manufacture of formaldehyde, the process which comprises heating -a gaseous mixture comprising methyl chlorid and oxygen to an oxidizing temperature at which formaldehyde can exist, and recovering resultant formaldehyde.

14. In -the manufacture of formaldehyde,

the process which comprises reacting upon methyl chlorid With oxygen at a temperature Within the approximate range of 400 C. to

p100; C., and recovering resultant formaldey15. In the manufacture of formaldehyde, the process which comprises passing a mixture containing predetermined proportions of methane, methyl chlorid and oxygen over a `metal at a temperature within the approximate range of 400D C. to 500 C., separating formaldehyde from the effluent gases, adding methane, oxygen and available chlorinev to the residual gases as may be necessary to restore approximately the original p-roportions of methane, met yl chlorid and oxygen,

and repeating the foregoing operations for production of more formaldehyde in a continuous cyclical procedure.

16. In the manufacture of formaldehyde, the process set forth in claim 15, 'further characterized by the fact that the catalytic compound employed is a reaction-promoting compound of an alkaline earth metal.

17. VIn thegmanufact-ure of formaldehyde, the process set forth -in claim 15, further characterized by? the fact that the catalytic compound employed is barium chlorid.

18. In the manufacture of' formaldehyde, the process set forth in claim 15, further characterized by the fact that the catalytic compound'employed is barium chlorid and that the reaction temperature is maintained at about 480? C. l

19. In the manufacture of'formaldehyde, the process' set forth in claim 15, further characterized by the fact that the mixture passed over said' catalytic compound comprises about four parts methane, methyly chlorid and one part oxygen, by volume. l y I 20. In the manufacture of partial oxidation products of hydrocarbons, the process halogenating a hydrocarbon inheated gaseous condition and cxidizin the resultant halogen derivative to split o hydrogen halid and form the desired oxidation product.

21. In the manufactme of partial oxidaone part which comprises halogenating a hydrocarbon in heated gaseous condition in the presence of available oxygen and of a catalyst aiding' oxidation of hydrogen halid, an.v excess of said'hydrocarbon being also present, and separating a desired oxidation product from the reaction gases,

22. In the manufacture of partial oxidation products of paraiiin hydrocarbons, the process which comprises halogenating and oxidizing a paraffin hydrocarbon in gaseous conditionwith the aid of a catalyst comprising a *reaction-promoting compound of a divalent element.

23. In the manufacture of partial oxidation produc-ts of paraffin hydrocarbons, the process which comprises chlorinating and oxidizing a paraiindiydrocarbon with the aid of a catalyst comprising barium chlorid.

24. In the manufacture of formaldehyde, the process which comprises halogenating and oxidizing methane with the aid of a catalyst comprising a reaction-promotingA compound of a divalent element.

N25. In the manufacture of formaldehyde,

the process which comprises chlorinating and oxidizing methane with the aid of a catalyst comprising barium chlorid.

26. In the manufacture of formaldehyde, the process which comprises heating a gas. eous mixture comprising methyl chlorid and oxygen to an oxidizin temperature at which formaldehyde can exlst, in the presence of a catalyst comprising a reaction-promoting compound of a divalent element, and recovering resultant formaldehyde.

27. In the manufacture of formaldehyde, the process which .comprises reacting upon methyl chlorid with oxygen at a temperature withinthe approximate range of 400 C. to 500 C. in the presence of a catalyst comprising a reaction-promoting compound of 'a divalent element, and .recovering resultant formaldehyde..

Y In testimony whereof I hereunto afxmy signature.

4FRANCIS J. CARMAN;