US2366725A - Process for oxidizing olefins - Google Patents

Description

Jan. 9, 1945. D, GARDNER 2,366,725

PROCESS FOR OXIDIZING OLEFINES Filed Feb. 26; 1941 C2H4O etc.

Hearer To I70 51 Insu laTed Z1 Heafer INVENTOR wow/w Kn? PMWI ATTORNEYS m nted 9, 1945 I PROCESS FOR oxrnrzmo OLEFINS Daniel GardneryNew'Yoi-k, N. Y., assignor to Gardner Thermal Corporation, a corporation of Delaware Application February 26, 1941, Serial No. 380,622 15 Claims. (01'. zen- 3485) at a temperature safely below that at which the This invention is a novel process for the oxidation of olefins, being the treatment of unsaturated hydrocarbons of the ethylenic series, typically represented by ethylene gas, for the purpose of" producing on "an industrial scale the ethylenic oxide, preferably in a continuous operation, and

the collectionof such oxide with or without the further step of conversion othereof to an aqueous or other derivative product such as glycol. While ethylene will be referred tofor illustrative purposes, the process hereof is applicable to the treatment of propylene and the higher homologues, by appropriate variations of temperature, duration, selection of catalysts and other factors involved; The olefin gas may be in strong concentration obtained in known ways, or may be very dilute as, when accompanied 'by other gases from cracking operations. gen may be supplied as air or in another gas, for example as nitrous oxide. The ingredient gases however should themselves be in a quite pure condition and free from moisture or other agents which might interfere with or reduce the efll-ciency of the process.

In a copending applicatiomserial No. 380,284,

filed February 24, 1941, has been disclosed 8. Drooess for treatment of unsaturated hpdrocarbons,

carried out in a non-acid liquidbath, preferably an organic liquid or alkaline reaction.

An object of the present inventionis to provide a practical and useful liquid bath system for this subject, wherein the bath is of acid reaction and comprises preferably a plentiful inorganic or mineral acid. A particular object is to permit operations at relatively low temperaturesso as toyield' the desired oleflnic oxides without danger of dis- The necessary oxy- I integration by isomerization or otherwise, while vmay firstbe recited as follows. The underlying principle may be described as the process, which may be continuous, of oxidizing an olefin, which process comprises conducting streams of gases containing respectively the olefin and the oxygen,

, supplied in equimolecular proportions i. e. substantially accordingto their combining weights,

; and passing each of these through a hot bath of a suitable non-aqueous liquid wherein is dispersed or dissolved a catalyst eflectlve to promote the reaction for the combination of the olefin and the oxygen to form the'olefinic oxide, carried out olefin or its oxide is liable to disintegrate, asby isomerization or polymerization. By non-aqueous is meant that the bath should contain no appr ciable q antity of free water, not referring to the water of combination which is a component of certain acids. The characterizing features include the following. The bath vahicle is of strong acid character, as a concentrated solution of an acid, preferably-a mineral acid, and containing no free water. The acid, as sulfuric acid, is adapted to take part in the reaction by first combining with the olefin to form an intermediate product, as ethylsu'lfuric acid, which next yields the olefin for combination with the oxygen. The ability of such'a bath to absorb chemically a given olefin usually ceases within a certain temperature range above which'the reaction reverses, so that the bath should be well below such transition temperature. Under these conditions the firstreaction step occurs readily, and the catalyzer is for promoting the second step of the de-' scribed indirect oxidation.

This invention then has to do with the catalytic oxidation of 'ethylenic hydrocarbons, particularly as taking place when passing a current of air or oxygen through an alkylsulfuric compound, such as 'saidethylsulfuric acid, present or dissolved in an excess of sulfuric acid, the alkylsulfuric compound being continuously formed by interaction between the ethylenic hydrocarbon and the sulfuric acid, and thereupon continuously giving up its ethylene component to unite with the oxygen.

While sulfuric acid HzSOrwas mentioned it is but a preferred representative of acids available for the reaction bath of this invention, such as phosphoric, arsenic, boracic and selenic' acids;

telluric .being operative but too'costly. These acids may be classed as examples of the group of mineral acids, but not to the exclusion of other kinds of acids which can first takeu'p the olefin and thenyield it to oxidation.

It is advantageous to add auxiliary agent or salts to the bath, for example, to add to sulfuric acid one or more of the acid salts NaHSO4 or KHSO4. ,These are-found to assist the taking up of the olefin, possibly by active or. mass action.-

Platinum black or sponge is an instance of a suitable catalyzer, and others will be enumerated after reciting an illustrative example of the invention; remembering that any catalyst is subject. to fatigue, and that occasional switching of the process from one bath to another is advisable to permit refreshing or activating th in this and'other respects 7 "L erization or otherwise, which in the case of operating also-"to regenerate the following formula:

bath.

' 'rhe supplied ethylene gas, andasweu the oxygen-containing gas, nitrous oxide, maybe preheated while being conducted tothe'furnace or i reaction vessel. Thelbath being maintained between about 145 and 155, 'withoutside limits of 140' and 160, the preheating of the supply'gases. may beffor example to 170. The bath maybe -in the form of a shower, or preferably a column of the liquid vehicle-through which the respective gases may be passed by 'blowlng .them"into the bottom of the bath to ascend therein in the form of fine bubbles adapted efiectively t'ocohtact the bath liquid and other agents. I

Theltreatment bath'may consist of pure sulfuric acid, and by the joint ascent through the 20 bath of the respective gases there may be. some degree of direct combinatiomor oxidation of the ethylene, but in the main the reaction, isja twofold one. In the flrststep the ethylene makes combination'with part of 'the'acid, which loses to the ethylene one atom of hydrogen in the process.

Thus is formed the intermediate. product ethylsulfuric acid or acid ethyl sulfate, which is an ester and constitutes one of the'alkyl sulfur compounds. The temperature is preferably between 145 and 155, safely below the transition temperature of about 160 above which the first step of vices 22; and any known means may be employed for preheating the gases between blowers and dischargers, such as the heater 23 shown conven tionally as a box through which the flues extend.

The productgases are conducted from the fur-'.

- .nace or vessel by an outtake pipe 25 leading to a shown in the form of ultraviolet tubes 21 positioned within the reaction space.

. Manifestly the gases outgoing at pipe 25 could be recirculated back through'intake pipe l5 or for more exhaustive reactions; and in such way T the process could be discontinuous'if desired, or

' batch by batch.

the reaction can not occur; and is below the break-up point at which there is a tendency of the ethylene or its oxide to disintegrate by isom- Byway of assisting the step of combination of ethylene and sulfuric acid there may be added to the bath an. auxiliary agent or salt, for which the acid salts, sodium or potassium bisulfate, or T 1 vailing typeset industrial installations that are .C2H5QSO3H+O C2H4Q+TI2$OA The product gas or ethylene oxide bubbles up and out of the bath, along "withthe various inert, or idle gases withwhich the ethylene and oxygen the sulfuric ac d by supplies-were entrained; and the entire stream of outflowing gases may bapassed-to a suitable point for the, collection of the ethylene oxide or for its conversion into derivative products.

The example recited isillustrated by the single diagrammatic figure of drawing with legends indicating suitable materials and temperatures. The liquid bath l0 represents either a spray or a column as shown, through which the supply gases] must flow. The furnace or vessel ll, of non-corrosive material, contains the reaction chamber or space within whichis maintained the bath. 6

The olefin is shown fed bysupply pipe l3, blowerl4 and passage or flue l5 to a discharge! vI Bshown as a perforated extension of the pipe. "The oxy- 7 Supplemental explanations The different catalysts to be enumerated all have in commonthat, when dispersed in hot sul- I furic acid or another suitable acid solution, such as molten bisulfate of sodium or potassium, they act catalytic'ally within a definite temperature range and thereby contribute to the oxidationof any of the ethylenic hydrocarbons. By this process, and these catalysts,-either pure ethylenic hydrocarbons' can be submitted to oxidation, or'the same hydrocarbons mixed with other hydrocarbons; as with gases obtained by modern 011 cracking processes or those resulting from coke-oven ror similar operations. e v

For the most part the indicated catalysts have already been made use of in various chemical processes; butit-is believed to be novelftc apply said catalysts in the process" or system herein disclosed or in the'conditions as already stated or summarized; the matters of novelty being or. practical value since they afiord an economic advantagawithout need of discarding the prenot only costly but often complicated.- The var- 'num black in'formof a suspension in concentratthe metal in very fine state for suspension or colloidal dispersion therein. The oxidation of ethyl- -160 CL, and goes as follows:

gsoLczHmH-F02*2OHQCHmdHLHSO4 ene i carried out at a. temperature below about By treatment withpotassium hydrate the so ob tained product givesethylene p d in the same oncmcrnrrsomzggd-s :i cmcmp+ms04+2mo If desired, the ethylene oxide can be'introduced into water in order to obtain ethylene glycol.

(2) Palladium black in very finely divided state dissolves in concentrated sulfuric acid, thus givgen, as air or nitrous oxide, is-supplied by pipe I 8 and driven by blowerQlQ through passage or flue V 20 to perforated-discharger 2|. The dischargers are placed lowtodeliver the gas streams as'bub-i blesvascending in, intimate mixture through the fling-a certain advantage over platinum black.

Otherwisetheactionjsa very much similar one.

I (3),.Silver sulfate. use of silver salt': I more particularly of silver sulfate, is well estab-'= lished for catalysisfor instance for the produc-y tion of esters, as by action-upon halogen alkyls." Silver sulfate-is soluble in concentrated sulfuric F ascavas acid, affording good results of oxidation, even at n a temperature of up to 250. a

(4) Copper sulfate works in similar manner I to silver sulfate: but it has a lower melting point.

(5) Thallous sulfate. This salt functions also like silver sulfate. However, it is well soluble only in dilute sulfuric acid, and besides has the drawback of going over into thallic sulfate.

(6) Manganous sulfate is soluble in concentrated sulfuric acid; and can be easily incorporated in the acid in a suitable quantity. It gives lower yields when used as a catalyst.

(7) Ferrous sulfate is a well known catalyst in certain organic reactions. This is a cheat! acid, HzSeOa, which corresponds to sulfuric acid;

and is particularly appropriate in an oxidizing bath of selenic acid, and dissolves also in sulfuric acid. The catalytic'action is marked, but it is necessary to workat the lowest practical temperature, below 260, to avoid decomposition ,,and carrying away of the salt.

(10) Silver nitrate. Like silver sulfate, the nitrate'has already been frequently used in orthereby practicallyextracted from the supply gases and rendered available forindustrial purposes.

Under the principles of this invention the bath must be acid; and while strong acidity is preferable, this may be weakened so long as it remains liquid up to the hot reaction temperatures used, such as about 160 or 200; and as instances within this suggested equivalent may be men-' tloned molten salts, as .NazSOs or mSOu, or a stable hydrocarbon, liquid and acid, operated under hot temperature and with the catalyst incorporated.

What is claimed is:

1. The process of oxidizing ethylene or other olefin comprising conducting supply streams of.

- gases containing respectively the ethylene and the oxygen supplied in substantially equimolecularproportions,passingthe ethylene and'the oxygen' gases into and through a substantially nonaqueous liquid bath of a concentrated mineral acidof the group consistingoffsulfuric, phosphoric, arsenic, boracic and selem'cacids, in

ganic processes. Its great advantage consists in its low melting point of 212. It is easily incorporated ,in concentrated sulfuric acid.

(11) Lead nitrate has given satisfactory results as a catalyst. When incorporated in concentrated sulfuric acid, it partly goes over into lead sulfate, which precipitates in the form of a fine powder, since it is only slightly soluble.

(12) Thallous nitrate is an excellentcatalyst and has a relatively lowmelting point, but is poisonous. The salt otherwise acts like thallous sulfate, but permits working at lower'temperatures, which is always an advantage when'work ing 'with .ethylenic hydrocarbons and their de-' rivatives. s

The above twelve series of salts, includingj other sulfates, nitrates catalysts were among a long I which bath is disperseda catalyzer which is stable in the acid bath, the oxidation being in two reaction steps, theethylene first combining with the acid to form ethylsulfuric acid as an intermediate product, and the intermediate product then yielding the ethylene to combine with the oxygen as ethylene oxide while the acid is regenerated, the catalyzer being a substance other than the bath acid acting to promote the.

second step, and the temperature being maintained at a reaction temperature well below that of liability of the ethylene or its oxide to disin tegrate, and within a temperature range in which the first step can occur, between about 145 and 155.

2. The process of oxidizing an olefin comprising conducting streams of gases containingrespectively the olefin and the oxygen supplied in substantially equimolecular proportions and sub stantially at atmospheric pressure, .passing the olefin and the oxygen through aheated bath of substantially non-aqueous concentrated acid liquid wherein is dispersed a catalyzer other than the bath acid which is stable in the bath and acts'to promote therein the combination of the olefin andthe oxygen to form theolefin oxide, a

andn aintaining said bath at a reaction tem- 'perature between about 140 and 160 C.

3. The continuous process of oxidizing an I olefin comprising passing preheated streams of and selenates thatwere tested, others of which.

were not satisfactory. The twelve have been especially mentioned as illustrativecatalysts be-;.

cause, they allgave satisfactory results, buttheirmention is not to exclude others that trial may I show to be useful.

. Since at the bath verted in passingthrough the reaction zone, andsince at the speed and shortduration of passage they are not subject to sulfurationggas'es is suing from modern cracking processes or'from' coke-ovens can be passed directly; through the,

above described system, in their "diluted condi- V temperatures designated sat-'1 urated hydrocarbons are not attacked' g c s gases containing respectivel 'the olefin andthe oxygen through a heated bath of substantially non-aqueous concentrated acid liquid wherein is dispersed a catalyzer other than the bath acid jwhich'isstable in the bath and acts to promote -therein'the combination of the olefin and the oxygen to form the olefin Oxide-,and maintaining said bathat a reaction temperature well below thedisintegration temperature of the olefin tion, without fear or impairingthe reactions or,

contaminating the products desired. In other words, under the described process conditions, only the ethylenic or other unsaturated hydrooxide." w

- 1 '4. The process of] oxidizing an olefin comprising conductingstreams of gases containingrespectively' the olefin and the oxygen, passing the olefin .and the Oxygen through a heated bath of substantially non-aqueous concentrated acid liq uid wherein is dispersed a catalyzerfwhich is stable in the acid bath, thereby to cause a-two- -1 stage reaction, the olefin first forming an inter carbons are attacked, these 1 taking part in; the j chemical changes and becoming rapidly trans-.

7 formed intothe respective oxides or-glycols. The i entire content of the ethylenic compounds-is mediate compound withthe bath acid which compound thereupon yields the olefin for com binationwith the oxygen; and maintaining said bath ata reaction temperature well below they temperature of reversal of the first reaction stage; the catalyzer being. an added substance other than the bath acid adapted to promote the second reaction stage with the olefin oxide as a product, and such second stage acting to regenerate the acid of the bath.

,5. A process as in claim 2 and wherein the reaction bath is of an acid liquid containing an acid of, the group consisting of the mineral acids, sulphuric, phosphoric, arsenic, selenic.

6. A process as in claim 2 and wherein the non-aqueous reaction bath consists of sulfuric acid.

7. A process as in claim 2 and wherein the nonaqueous reaction bath is of an acid liquid containing selenic acid.

8. A process as in claim 2- and wherein the non-aqueous reaction bath is of an acid liquid comprising molten acid salts of the group consisting of sodium sulfate and potassium sulfate.

9. A process as in claim 4 and wherein the non-aqueous acid bath is fortified with; an auxiliary agent or acid salt adapted to promote the first reaction stage, selected from the group consisting of sodium bisulfate, potassium bisulfate and a mixture of the two.

10. The process as in claim 4 carried out with a catalyzer which is a metal salt soluble in the non-aqueous bath and selected from the group consisting of the sulfates of silver, copper, iron, thallium, manganese, tellurium and nickel.

11. The process as in claim 4 carried out with a catalyzer which is a metal salt soluble in the non-aqueous bath and selected from the group consisting of the nitrates of silver, lead and thallium.

12. The process as in claim 4 and wherein the catalyzer is palladium black.

13. The process as in claim 1 and wherein the catalyzeris of the group consisting of the sulfates of silver, copper, iron, thallium, manganese, ,tellurium and nickel.

14. Theprocess of oxidizing an olefin comprising conducting streams of gases containing respectively the olefin and the oxygen passingthe olefin and the oxygen jointly through a bath of a substantially non-aqueous acid liquid wherein is dispersed a catalyzer which is stable in the acid bath and acts to promote the oxidation hot reaction, and maintaining said bath at a reaction temperature Well below the temperature of disintegration of such oxide, such catalyst being selected from the group consisting of the sulfates of silver, copper, iron, thallium, manganese, tellurium and nickel. I

15. The process of oxidizing an olefin comprising conducting streams of gases. containing respectivel the olefin and the oxygen supplied in equimolecular proportions, passing the olefin and the oxygen jointly through a bath of a substantially non-aqueous acid liquid wherein is dispersed a catalyzer which is stable in the acid bath and acts to promote the oxidation hot reaction, and maintaining said bath at a reaction temperature well below the temperature of disintegration of such oxide, such catalyst being selected from the group consisting of the nitrates of silver, lead and thallium. 1

16. The process of oxidizing. an olefin comprising conducting streams of gases containing respectively the olefin and the oxygen, passing the olefin and the oxygen jointly through a bath of a substantially non-aqueous acid liquid wherein is dispersed a catalyzer which is stable inthe acid bath and acts to promote the oxidation reaction, and maintaining said bath at a hot reaction temperature well below the temperature of disintegration of such oxide, and below about to C.; such catalyst being palladium black.

DANIEL GARDNER.

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