DE808834C - Process for the catalytic oxidation of olefins in the presence of cuprous oxide - Google Patents

Description

Process for the catalytic oxidation of olefins in the presence of cuprooxide The invention relates to a process for the oxidation of olefins, containing at least three carbon atoms, in the presence of a cuprous oxide catalyst for the purpose of obtaining unsaturated aldehydes or ketones between two carbon atoms of aliphatic character have an olefinic bond, one of these Carbon atoms bonded directly to the carbon atom of the carbonyl group. The process also results in improved olefin utilization it offers other advantages as well. In a preferred embodiment, deals the present invention in particular with a cycle process to carry out such catalytic oxidations of olefins of the aforementioned type.

The catalytic oxidation of olefins containing at least three carbon atoms contain, by bringing the olefins into contact with cuprous oxide or a solid, Contact mass containing cuprooxide in the presence of oxygen and under conditions which is a substantial conversion of the olefin into an unsaturated aldehyde or a ketone with the same number of carbon atoms per molecule as the olefin, favor is known.

Under certain conditions, especially when the aforementioned oxidation process is carried out in the circuit, e.g. B. by recycling unreacted olefin, a decrease in the effectiveness of the catalyst is noted, with the speed this deterioration is greater or greater depending on the reaction and the working conditions can be smaller. Examination of the catalyst shows no obvious one modification the same during the decline of its effectiveness. There are hitherto frequent or occasional reactivations of the catalyst required become, it being assumed that during the oxidation of the olefin an irreversible Change in the cuprous oxide catalyst occurs, z. B. a change in the crystal structure or in the degree of oxidation, which is responsible for the decrease in activity will. Since the reactivation treatment generally interrupts the oxidation process requires, it is desirable and- for economic or large-scale work It is almost essential to find a way of working that will avoid reactivation because in this way an almost uninterrupted work is made possible can.

The present invention is based on the discovery of such improved mode of operation, through which in the aforementioned catalytic oxidation of olefins under the special conditions under which in the cuprooxide catalyst supplied reaction mixture contains a considerable amount of carbon monoxide, improved results are achieved. The carbon monoxide can sometimes be in an or be contained in several of the starting materials, e.g. B. in the olefin, as it is from his Source of supply for application in which "is experienced as incidental contamination same. More common, however, are the amounts of carbon monoxide with which the The present invention is concerned, then found when the aforesaid catalytic The process is carried out in a cycle, d. H. when excess oxygen and or or excess olefin, which or which from the oxidation stage of the Process originates, is recycled over the same or a different cuprous oxide catalyst bed with the addition of new amounts of a reaction component or both components. if also carbon monoxide only in relatively small quantities as a by-product of catalytic oxidation of olefins is formed, so can nevertheless arise under such Cycle conditions considerable amounts of carbon monoxide in the reaction mixture enrich, which led to the cuprous oxide catalyst and partly in the circuit is traced back to this.

It has surprisingly been found that by removing the Total amount or approximately the total amount of any carbon monoxide present the reaction mixture fed to the cuprous oxide catalyst was significantly improved Results obtained in carrying out the aforesaid olefin oxidation process can be. Particularly among the advantages is an increased overall utilization of the To name olefins, thereby saving in the process and the elimination of Losses. In addition to the savings achieved in this way, there is also an increase Catalyst effectiveness, especially under the constant conditions when carrying out the process in a cycle. Another benefit is the reduction of any possible harmful influences which such work in the circuit could otherwise have on the properties of the catalyst.

In the present description, the expression olefins means both understood open-chain as well as cyclic olefins. Among the numerous olefinic Compounds, «velohe for use as starting materials for the present process are suitable, the following can be mentioned: propylene. i-butene, 2-butene. Isobutylene. Diisobutylene, i-pentene, 2-pentene, 3-1''Ietliyl-i-butene, 2-methyl-2-butene, i-hexene, 2-ilexene, 4-methyl-ipentene, 3, 3-dimethyl-i-butene, 4-methyl-2-pentene, i-octene, Cyclopentene, cyclohexene and 3-methylcyclohexene. These `` er) in-dations and their various Homologues can be substituted by in the core and / or in the side chains straight-chain alicyclic and / or heterocyclic radicals. The olefins köt; ii; n individually or among each other. mixed or mixed with the corresponding or treated with other saturated organic compounds. Conversions that can be carried out according to the method of the present invention z. B. the conversion of propylene to acrolein, isobutylene to methacrolein, alpha- or 1; eta-butylene to methyl vinyl ketone, i-pentene or 2-pentene to ethyl vinyl ketone and / or 3-penten-2-one, 2-methyl-2-butene to give 1lethylisoprolienviketon and cyclopentene to 2-cyclopenten-i-one.

The cuprous oxide catalyst is preferably supported by or finely mixed with a carrier material such as silica gel, silicon carbide in the form of porous pieces or pumice stone. The preparation of the catalyst can, for. B. be done by treating the degassed carrier with a concentrated solution of cupric nitrate or chloride or with an ammonium compound containing copper, such as copper ammonium nitrate, whereupon the nitrate or ammonium compound is decomposed to cuprous oxide, first by heating the dried carrier to about 250 to 400 ° in a slow stream of air and then by reducing the cupric oxide so formed to cuprooxide with hydrogen or another reducing agent. Essentially the same procedure is followed when using cupric chloride, only repeated oxidation and reduction may be required.

When the partial oxidation of the olefins is carried out in the presence of the cuprous oxide catalyst, the reaction temperature, ie the temperature of the catalyst, is preferably kept in the range from about 200 ° to about 450 °, although temperatures up to etv-a f oo = 'are also used can. The temperature used depends primarily on the catalyst. the particular olefin to be treated, the correspondingly chosen conditions in terms of throughput rate or contact time and the V ratio of olefin to oxygen. Apparent contact times of about 0.1 seconds to about 10 seconds generally give satisfactory results. The apparent contact time, cl. H. the time in seconds during which an \ "olu :: iene unit of the gas gas, measured under the real.:tiori;l>edingtingen, is in contact with a unit of the apparent catalyst volume can be calculated, for example, from the apparent Volume of the catalyst bed, the average temperature of the catalyst, the pressure, if this is different from atmospheric pressure, and the flow rates of the various components of the reaction mixture. Oil ratios of olefin to oxygen between about i: t and 30: i generally give satisfactory results; ltnis #: ° from about 2: i to about 6: i are preferably used.It has been found that failure to regulate Teinperattit, e.g. by diluting the reaction mixture with I), by working with a The excess of olefin and / or through the use of a carrier or support material which is a good thermal conductor, the oxidation to form carbon dioxide xyd and water at the expense of the desired product. The cuprous oxide can also be used alone or deposited on a carrier material in the form of dust or in a liwelreztistand and moved to distribute the heat of reaction. The process, which can be carried out at free pressure, at, above or below atmospheric pressure, is carried out in the most expedient manner in the vicinity of the atmospheric pressure.

4 \ 'If an olefin with at least three carbon atoms is so in the presence is oxidized by cuprous oxide, colloidal ion oxide is one of the subordinate by-products the reaction, which is generally formed in small amounts. For example In one experiment propylene, oxygen and steam were used with a cuprous oxide catalyst gebraolit in contact, which was held to about 410 to, being about 65% of the wasted propylene were converted into acrolein, while i y% of the was consumed Propylene in carbon dioxide found about 30; 'o were converted into carbon monoxide and the remainder consisted of minor differences in other reaction products. 1 'in a similar experiment in which Isolrutyleri converted into lletllacroleiti the amount of carbon monoxide formed was again less than 50% of consumed olefin. f e according to the special working conditions can in individual cases slightly larger or smaller relative amounts of carbon monoxide are formed; in general, however, it is to be expected that less than about 10% of the olefin in Carbon monoxide are converted.

The colylenic oxide formed is in accordance with the present invention underlying knowledge a pronounced catalyst poison for the cuprcxrxyd- Catalyst. Its presence in the reaction mixture can be even in small amounts have an extremely negative effect on the activity of the catalyst. This poisoning irl: titig of colilenniotioxide was surprising because Carbon monoxide is vain of the products of the oxidation reaction and therefore one could not expect that there would be a specific, poisoning effect on the catalyst especially since it is known that cuprous oxide is an effective catalyst for oxidation from carbon monoxide to carbon dioxide. It has been found that carbon dioxide, which is also formed as a product of the reaction, no detectable inhibitory Has an effect, but that its effect is essentially only that of an inert one Diluent is generally similar to that of steam, nitrogen or saturated hydrocarbons on the course or extent of the reaction can be compared.

The inhibiting effect of the carbon monoxide on the catalyst is _ partly dependent on the temperature of the catalyst. At catalyst temperatures below about 500 ° the presence of only 1 percent by volume of carbon monoxide is already present in the reaction mixture a significant effect in terms of reducing the activity of the catalyst, while at higher catalyst temperatures somewhat larger proportions of carbon monoxide can be admitted. In a cycle process for the oxidation of olefins can that is, the amount of carbon monoxide formed during a single run be less than the amount which would deactivate the cuprous oxide catalyst. If, however, excess reaction components and those relatively minor Amounts of carbon monoxide are returned in the circuit, the concentration can increase increase the carbon monoxide in the reaction mixture very quickly up to a value which is above that amount which allows optimal effectiveness of the catalyst.

According to the invention, the method for the catalytic oxidation of Olefins having at least three carbon atoms in the presence of a cuprous oxide catalyst for the purpose of the formation of unsaturated aldehydes or ketones, the measure of a reduction the carbon monoxide content of the reaction mixture fed to the catalyst to one Value which is below the value at which there is a substantial reduction the activity of the catalyst under the prevailing working conditions would.

In general, it has been found to be desirable to concentrate of carbon monoxide in the gaseous mixture that is fed to the catalyst, to less than about 0.5 percent by volume, preferably less than about 0.2 percent by volume, to keep. Whether there are excessive amounts of carbon monoxide in the various components of the supplied mixture are present, can be carried out in each individual case by a person skilled in the art can easily be determined on the basis of suitable analyzes and the ones used Operating conditions.

If one or more components of the catalyst conducted reaction mixture an amount of carbon monoxide of more than about 0.5 percent by volume of the mixture, it is desirable before contact of Reaction mixture with the catalyst to remove such an amount of carbon monoxide, that the carbon monoxide content of the mixture is less than 0.5 percent by volume, preferably less than 0.2 percent by volume.

For the total or partial removal of the carbon monoxide, which can be carried along by one or more of the reaction components Various methods can be used and the present invention provides one such removal generally preceded without regard to the specific for this purpose method used to be limited. However, some are said to be particularly preferred Procedures for removing carbon monoxide are described in more detail. Since the advantages of the present invention are particularly evident when the oxidation reaction is carried out in a circulatory process, should, in particular on such circulatory processes Be referred to.

In a cycle process for the oxidation of olefins with at least three carbon atoms becomes a stream of a gaseous mixture containing the olefin and contains oxygen, brought into contact with the cuprous oxide catalyst, and the resulting mixture, which unreacted olefin and / or unreacted Contains oxygen, after separation of the unsaturated aldehyde or ketone with additional reaction components and / or with diluent gas via the the same or a different catalyst bed recycled. In such a cycle process according to the present invention, at least part of the residual mixture to be returned treated for all or substantially all of the carbon monoxide contained therein separated, which prevents the accumulation of carbon monoxide in the reaction system while at the same time maximizing the utilization of reactants, in particular of olefins, and a high degree of efficiency is achieved.

It can be noted that if a part of the recirculated stream of unconverted reactants offensiohtlirh to avoid an increase in the carbon monoxide concentration in the reaction system could be used, the rate of carbon monoxide formation is such, that often the removal of a much larger amount of unreacted olefin would be required in one pass than implemented in such a pass to prevent the excessive build-up of carbon monoxide.

The drawing explains an arrangement of apparatus for implementation of the method according to the present invention in individual special embodiments. The drawing is for illustrative purposes only and therefore are different Parts of the additional equipment, which if desired or .required by a specialist can be easily supplemented, not shown.

In the device shown, the reaction mixture, which the olefin, e.g. B. propylene, a diluent such as steam, and oxygen or Contains air, introduced through the line io into the reaction vessel i i, which contains the cuprous oxide catalyst and by means of heating devices arranged outside or inside, which are not shown, is kept at the desired reaction temperature. The gaseous mixture leaving the reaction vessel is passed through line 12 Led into the condenser 13, which by water o. The like. That enters at 14 and exits at 15, can be cooled. The cooled mixture is passed through the pipe 16 to the gas separator 17, where the liquefied part of the mixture is withdrawn and through line 18 for the purpose of further separation and / or purification of the desired product contained therein is derived.

The gaseous part of the mixture is passed through the gas separator 17 the line i9 led to the pump 2o, through which the mixture is compressed if desired can be used to facilitate subsequent operations. Got from the pump the mixture via line 21 into an absorption tower 22 or other device for the recovery of desired carbonyl products contained in the gaseous part of the mixture stayed behind. When the carbonyl product is water soluble, e.g. B. acrolein, the gases can be sprinkled with water, which passes into the absorption tower inlet 23 is introduced. The solution obtained is scanned through line 24, pressure relief valve 25 and line 26 for the purpose of separation and / or cleaning of the so separated Carbonyl product are withdrawn.

After the desired unsaturated carbonyl product has been separated off The unreacted olefin can be oxidized in order to separate the contained therein Carbon monoxide can be treated in practically the entire amount. The drawn Facility includes a device that is used to carry out this separation after two special procedures is suitable. These two procedures can be used individually, independently can be applied from each other or expediently at the same time.

According to one of these separation processes, the remaining gas which leaves the sprinkler tower 22, after separation of the unsaturated carbonyl product or in other words the reflux flow through line 27 via valve 28 and line 29 into an absorption vessel or other effective device for the selective separation of unreacted Olefin passed from the remaining gas. In the drawing, the absorption device 3o is shown as a sprinkling column in which a liquid that is a solvent for the olefin but a nonsolvent for carbon monoxide, e.g. B. an organic solvent such as kerosene, gasoline, an ester or a ketone, brought into intimate contact with the gaseous mixture. The gases not absorbed in this process, which can consist of nitrogen, oxygen, carbon dioxide and carbon monoxide, can be blown into the air through line 31 via valve 32, line 33, valve 34 and outlet 35; or they can be passed via line 31, valve 32, line 33, valve 36 and line 37 into line 45, which will be mentioned later. The absorption liquid, which contains the absorbed or dissolved olefin, is fed via line 38 and pumps (not shown) into the stripping column 39, in which the olefin is separated from the solvent, whereupon the solvent is returned via line 40 to the sprinkling column 30 . The olefin recovered in this way, which is practically free of carbon monoxide, can be passed from the stripping column 39 via line 41, pressure relief valve 42 and lines 43, io into reaction vessel II and passed with a fresh inflow of reaction components over the same catalyst bed or together with fresh inflow be fed into a second reaction vessel, which also contains a cuprous oxide catalyst.

The second method for removing carbon monoxide is the All or part of the gases leaving the absorption tower 22 through Line 27, valve 44 and line 45 passed directly into a heated reaction vessel 46, in which there is a bed of a catalyst that promotes selective oxidation favored by carbon monoxide in the presence of an olefin. When the absorption tower 22 leaving gases too little oxygen to react with the total amount of Can contain carbon monoxide before being passed through the reaction vessel 46 additional oxygen, air, etc. can be supplied. In the vessel 46 is then the carbon monoxide by reaction with the oxygen and contact with the catalyst selectively oxidized to carbon dioxide. After contact with the catalyst in this The gas mixture freed from carbon monoxide can pass through the line in the reaction vessel 47 to the inlet for the reaction vessel i i or for a second reaction vessel to be led back.

It has been found that oxidation catalysts that under the name hopcalite are commercially available, used in the reaction vessel 46 can be to the selective oxidation of carbon monoxide in the presence of olefins to effect. These catalysts can be used as main components from about 35 to 7o Percentage by weight of manganese dioxide, from about 10 to 500/0 cuprous oxide and if desired Contain small amounts of other oxides such as cobalt or silver. A special one effective catalyst of this type contains e.g. B. about 5o% manganese dioxide, 300/0 cuprous oxide, 15% cobalt dioxide and about 5% silver oxide. The silver oxide can be omitted, without affecting the selectivity of the catalyst when used in the present process is deteriorated, thereby reducing the cost of the catalyst. That Cobalt oxide can also be omitted, although a catalyst obtained in this way is somewhat is less selective and less active when used in the present method will. Other catalysts used for the selective oxidation of carbon monoxide can be, are z. B. Manganese dioxide, copper chromite, iron oxide, nickel oxide, chromium oxide and mixtures of these with one another and / or with other metal oxides. Preferred Catalysts consist of about 35 to 75% manganese dioxide, from about 20 to 35% cuprous oxide and from about 5 to 30% cobalt dioxide. The catalysts can be made by precipitation of the oxides from a solution of nitrates or other soluble salts of the elements, thorough washing and drying of the collected precipitate.

The catalysts, which are made of a carrier material such as aluminum oxide, Pumice stone, kieselguhr, can be carried into the reaction vessel 46 in In the form of globules, fragments, lumps, etc. are introduced. The returned Current flowing in through line 45 can contact the catalyst be brought at a temperature conducive to promoting the desired reaction is effective and is generally between room temperature and 150 ° or higher. When the recirculated current is treated in this way, if at all, only a negligible oxidation of the olefin. Considerable at temperatures over 25o °, especially when using the more active catalysts the tendency towards excessive oxidation of the olefin; therefore, in general, the Use of temperatures below 25o ° is desirable. That formed from the carbon monoxide Carbon dioxide does not need to be extracted from the mixture of gases before being reintroduced in the reaction vessel i i to be removed.

It will be understood that numerous changes can be made in the construction and operation of the apparatus shown in the drawing. If z. B. only one method for. Removal of the carbon monoxide from the recirculated stream is used, the parts that are not required can be left out of the apparatus. If steam is used as the diluent in the mixture fed to the reaction vessel ii and air is used as the source of oxygen, advantages can be achieved by only allowing that part of the recirculated stream to pass through the valve 28 into the absorption vessel 30 which contains the inert gas, e.g. B. nitrogen, carbon dioxide, etc., which is to be blown out of the system. If pure oxygen is used instead of air, it is preferable to return a larger portion, up to the total amount of the recycle stream, via valve 44 and line 45 to reaction vessel 46. In this way, carbon dioxide and other inert, non-condensable gases can be retained in the recycle stream without the accumulation of excessive amounts of carbon monoxide. The amount of inert diluent, e.g. B. Steam, which would otherwise have to be supplied, can be reduced accordingly. If, in this last-mentioned case, excessive amounts of carbon dioxide were to accumulate in the reaction system, a suitable portion of the recycle stream can either directly or after prior separation of the olefin, e.g. B. in the sprinkling column 3o, or, according to another embodiment, the recirculated stream can be treated with an absorbent for carbon dioxide, such as solid alkali or alkaline earth or, for example, an aqueous solution of an organic amine, to some or all of the carbon dioxide remove.

While in the method described in the preceding paragraph and in the device shown, liquid absorbents have been used to remove residual carbonyl compounds in column 22 and the olefin in column 30 , these liquid compositions can also be replaced by solid adsorbents or absorbents become, such as B. activated aluminum oxide, activated charcoal o. The like. Which can hold back the material to be removed from the gas stream. The retained material can be coagulated from the solid adsorbents or absorbents either batchwise or continuously by known methods and treated further in the desired manner. The device shown is particularly suitable for the production of the lower, relatively volatile unsaturated aldehydes and ketones, such as acrolein, Methacrolei.n and Met @ livlvinyl'keton. If higher, less volatile unsaturated aldehydes or ketones are to be prepared, the necessary changes in the system for separating the carbonyl products from the reaction mixture can easily be carried out by a person skilled in the art.

Except as explained in the preceding paragraphs and in the drawing preferred embodiments, the invention also includes other methods of selective Removal of the carbon monoxide from the recirculated stream. So encompasses the invention also the removal of carbon monoxide in such a way that it can be removed in the presence of Iron oxide reacts with steam according to the equation CO + HEO = COQ + H ?.

The iron oxide can expediently be arranged in the heated reaction vessel 46 in place of the above-mentioned catalyst, and the recirculated stream mixed with steam can thus be used at a higher temperature, e.g. B. about 200 to 250 ° or higher gebradhi in contact. In a less desirable embodiment, hydrogen can also be added to the recycled stream and reacted with the carbon monoxide by bringing the mixture into contact with a hydrogenation catalyst which favors the reduction of carbon monoxide at a relatively low temperature, e.g. Y. nickel, cobalt, - platinum or iron. Because it is possible for excessive simultaneous hydrogenation of olefin present in the mixture to occur, it is generally preferred to remove the carbon monoxide by the selective catalytic oxidation method described in the preceding paragraphs. Another possible way of removing the carbon monoxide is to contact the recycled stream, which contains both olefin and carbon monoxide, with an adsorbent or absorbent which has a selective affinity for carbon monoxide. So z. 13. a 'liquid absorbent, such as an acidic solution of cuprous chloride, intimately brought into contact with the gas stream, e.g. 13. in a trickle column leading into the line:; is used in place of the reaction vessel 46, the amounts of absorbent being sufficient to reduce the chloride monoxide concentration to the desired value. The residual stream is then returned directly to the feed line of the reaction vessel ii, while the cuprocyl chloride solution is regenerated either continuously or intermittently by methods known in the art, e.g. B. in a stripping column to remove the absorbed carbon monoxide, whereupon it is returned to the trickle urine.

As an example of the practice of the present process, a stream of a gaseous mixture of propylene, oxygen and steam is brought into contact with a solid catalyst consisting of cuprous oxide supported on porous pieces of silicon carbide. The conditions are chosen so that they favor a substantial oxidation of the propylene lens to acrolein. The mixture leaving the catalyst chamber is cooled to condense the steam and part of the acrolein, while the remainder of the acrolein is removed by sprinkling the uncondensed gas with water. The remaining gas containing excess propylene is continuously recycled and mixed with the feed to the cuprous oxide catalyst. Under the conditions of this experiment, but without recirculation of the remaining gas, about 65% of the propylene consumed is converted to acrolein and about 80% of the oxygen supplied is consumed. The mixture leaving the cuprous oxide catalyst contains about 0.1 to 0.3 percent by volume of carbon monoxide. When the remaining gas mixture, which contains the excess of propylene, is returned (with a smaller portion being blown into the air in order to remove excess carbon dioxide formed during the reaction) into the stream supplied to the catalyst, while the other reaction conditions remain the same remain, a permanent concentration of carbon monoxide forms in the reaction mixture in contact with the catalyst, which is about 3 percent by volume, and the yield of acrolein decreases somewhat. while the rate of acrolein formation falls markedly. The consumption of supplied oxygen falls to about 30%, which indicates a decrease in the activity of the catalyst in recycling the gaseous reaction products. If the returned stream, instead of being combined directly with the feed to the isolator, is passed through a heated heat exchanger in which a bed of oil is present at a pressure of about 3.5 h / c1.12 -K a tal_vs <itor kept at, for example, i .so 'o: ircl, so that practically all of the carbon monoxide is oxidized to carbon dioxide without (ia a substantial oxidation of the remaining substances occurs of the recycle stream thus processed with the feed to the cuprous oxide catalyst under otherwise the same conditions as in the previous experiment, the constant concentration of the gaseous mixture of carbon monoxide in contact with the cuprous oxide catalyst is reduced to a value below about 0.2 The acrolein yield now remains about the same, but the rate of acrolein formation is two to three times as high he erli <ilit. and the consumption of oxygen increases to about 65% of the amount supplied.

Claims (5)

CLAIMS: i. Process for the production of unsaturated i @ 1 (le, liyde or ketitlie by catalytic oxidation of olefins having at least three carbon atoms in the vapor phase with oxygen-containing gases in the presence of a cuprous oxide catalyst, in particular for the production of full acrolein from propylene, characterized (Let the carbon monoxide gold of the reaction mixture delivered to the catalyst is held on a U'ert. which is below the \ Vertes at which under the conditions of work, a reduction in the activity of the catalyst would occur. 2. The method according to claim i, characterized in that (let the Concentration of the carbon monoxide in the mixture supplied to the catalyst less than about 0.5 percent by volume, preferably less than about 0.2 percent by volume, is set. 3. The method according to claim i and 2, characterized in that dal, i contains one component or more components of the reaction mixture fed to the catalyst carbon monoxide in an amount of more than about 0.5 percent by volume of the mixture, and that before touching the Reaction mixture with the catalyst such an amount of carbon monoxide is removed, (let the carbon ion oxide gel of the mixture which comes into contact with the catalyst is less than 0.5 percent by volume, preferably less than 0.2 percent by volume. 4. The method according to claim i and 2, characterized in that a continuous flow of a gaseous Reaction mixture, which contains olefin and oxygen, with the cuprous oxide catalyst is brought into contact, and that the unsaturated aldehyde or (read Ketone is old separated from the mixture obtained, at least part of the remaining mixture, which is a reactant originally fed to the catalyst contains, a treatment for the purpose of separating fully contained carbon ion oxide is subjected by the reactant and then the reactant combined with the gaseous reaction mixture fed to the cuprous oxide catalyst will. 5. The method according to claim 4, characterized in that at least one part of the remaining mixture containing carbon monoxide. under conditions which favor the selective oxidation of carbon monoxide in the presence of oxygen is brought into contact with a catalyst for the selective oxidation of carbon monoxide. f. The method according to claim 5, characterized in that the selective oxidation of carbon monoxide is carried out at a temperature below 25o °, z. B. between Room temperature and i5o °. Method according to claim 4, characterized in that containing at least a portion of the remaining unreacted olefin and carbon monoxide Mixture is treated with an absorbent, which is a solvent for the olefin, but a nonsolvent for carbon monoxide, and that the olefin from the .Absorptionsmittel and recovered to the gaseous, the catalyst fed reaction mixture is recycled.