DE1917814B - - Google Patents

Description

The present invention relates to a process for the continuous production of mixtures from Cyclohexanone and cyclohexanol. It concerns in particular the continuous treatment of oxidation products, which contain hydroperoxides and from the oxidation of C ^ ciohexane with oxygen or Air originate.

If you oxidize cyclohexane with oxygen or air, a hydroperoxide is formed. You can then this hydroperoxide either in situ as it is formed or later in another of that Further convert the oxidation vessel to different reaction vessel.

In the process of converting the hydroperoxide at the time of its formation, one can be present in the presence of agents that neutralize the acids formed in the course of the reaction, or in the presence of boric acid derivatives (boric acids, boric acid anhydrides or boric acid esters !!). All of these procedures lead to mixtures of oxidation products which contain relatively little hydroperoxide and order mainly from cycloalkanol.

The processes for later converting the drop hydroxide involve heating in the presence \ on granular catalysts, applied to carriers, which are arranged as Fcstbctt, proposed. Both during the oxidation and during the The viscous polycondensates formed by the hydroxide dehydration however, they tend to deposit on the catalyst bed and envelop the active substance. This leads to a progressive deactivation of the catalysts, which the course of tcehr addition proceedings long duration kcmpli / icrt. It has already been described an oxidation of cyclohexane with air in the presence of soluble catalysts based on it carry out of cobalt or chromium and then the optionally concentrated oxidation mixture without additional addition of a catalyst to heat to decompose the Mydiopcroxyd to derivatives, which by a later oxidation of adipic acid can deliver (British patent 777 087. that of the German Auslcgcsclirift 1 002 754 corresponds). This method also leads to mixtures of oxidation products, in (ii-ncn the cyclohexanol predominantly Amount is present [cf. test report a) and b) J. This also leads from the German translation I 114.SI0 mentioned process for the air oxidation of Cyclohexane in various reaction zones only to improve the overall level of adipic acid and their predecessors.

The need for cyclohexanone is now constantly increasing with the growing number and production of polymers and polycondensates, for which this ketone etvavere intermediate or solvent of choice represents.

ίο The various procedures above are therefore not completely satisfactory when one considers mixtures of cyclohexanol and cyclohexanone which are rich in cyclohexanone, want to produce from the corresponding cyclohexane, which is the only economically

borrowed is viable source material as one in this Trap at least some of the cyclonexanol formed dehydrate to cyclohexanone.

The aim of the present invention is therefore to provide a process for continuous production

ίο of mixtures of cyclohexanol and cyclohexanone, which are rich in cyclohexanone.

The erfindiingsgemäCe method for continuous Manufacture of mixtures of cyclohexanol and cyclohexanone that are rich in cyclohexanone.

by heating a solution of cyclohexylhydropcroxide in cyclohexane, which has been obtained by oxidation of cyclohexane in the liquid phase with a gas containing molecular oxygen, in the liquid phase to a temperature between 80 and 150 ³ Z in the presence of a soluble chromium derivative as a catalyst is characterized by that one works in several - but at least three - successively arranged reaction zones, the hydroperoxide concentration being kept at a substantially uniform value at all points within each individual zone.

All cyclohexane oxidation products, peroxide products and especially hydroperoxides can be used are treated according to the new procedure. but it should be noted that with this new type of procedure The advantage achieved is the greater, the more specific the oxidation products with regard to formation of the hydroperoxide have been produced, since in this case the proportion of undesired products in which the rising maicrial is minimal. In practice it is therefore generally advantageous to use an oxidation product to assume that by oxidation of cyclob ^ xane with air without the use of a catalyst, optionally under pressure, has been obtained i: t. where the temperature and the degree of conversion are chosen so that the formation of undesirable products is kept as low as possible. One works of course in an apparatus that does not catalyze the decomposition of the llydropcroxyd, which is im In the case of an apparatus made of stainless steel, a previous passivation, for example by means of pyrophosphates, requires. When the oxidation product is specially made for the formation of the hydroperoxide the oxidation is generally limited to a degree of conversion below 10 "and preferably to a degree of conversion between 2 and (>% the Oxych.tionsprodukle cyclohexanol. Cyclohexanone and various by-products. Such oxidizing

C5 products can, as they are, according to the invention Oxidation treatment. The Oxidationsprcdukt can, however, also before according to the invention

ir

H ',! L desired concentration can be brought. Including acetal, the teri.-alkyl chromates, for example teit.-

Jic reaction is exothermic. i-, i it however / to avoid Butyiehromat, and the Cycloalkylchromate, for example

· ,, η .hi strong l-rhil / ungcn, which for the achievement of good wise Cyclohexylchmmai. to name. The preferred

\ ii-i-euten are disadvantageous, / u Ixvoivugen. not / u forms are the octoates and the ten.-alkyl or cy-

k. ■ ij / L-iitricrie solutions to use. In practice 5 clohexylehromate. Ca the different Enlperoxy-

ivtcl.t not interested in / ustrehcn. Containing solutions of the dation zones cyclohexanol, one can do that

ι ι - .. '. daiionspmdukts with a concentration above IS "/" corresponding Chrom.it in the same zone by

.ii, Ciesaiv.tperoxjden eiiv.uset / .en. Since the oxidation leads to one of its precursor compounds, both

I; .ml μ is carried out under pressure, there is, for example, chromium trioxide or its complex with

.: i;, i.iches means for concentrating the m pyridine thus formed.

ι) >> dationsprcxlu! acs in, a relaxation de-, from The Kualysator amount can within wide limits . Only warm oxyda- vary, de * h one generally works in such a way that • ir to make iisprodukts. Such ovulation solutions are the amount of metal introduced by the catalyst L'ca can advantageously after the in the l'ranzö- a total of between 1 mg and 1 g per kilogram of l-lydro- -i-chen patent 1491518 described peroxides, which are used in the de-peroxidation treatment ;, theirs have been created. It is advantageous to contain amounts before undergoing solution. The squad Carrying out the Entperoxidierungsbehandliing catalyzer can into the first Entperoxidierungszone insaus the oxidation solutions at least partially the total introduced odei also between the different acids. containing them, for example a de-peroxidation zone and any suitable by washing with water. 20 funds are distributed.

In practice, the temperature can be the same for carrying out the ore, or the temperature can be continuously countered from one zone to the other process according to the invention, but it is generally between 80 and, if necessary, the previous oxidation product of the cyclo! 50 C. If the temperature is too low, the hexane falls into the first de-peroxidation zone with at least a part of the amount of catalyst not decomposing the hydroperoxide. One turns off, while at temperatures above 150 "C. the temperature of the zone is then passed through any suitable heat exchange medium for a given number of de-peroxidation zones and the throughput of the oxidation product, as a function of the can between 100 and this first zone selected degree of de-peroxidation I 30 C. 30. If the de-peroxidation temperature is above the boiling temperature of the mixture, the decomposition of the hydroperoxide takes place in stages, you can get the time the penetration of the cyclohexane solution from the apparatus under the autogenous pressure and If the additional pressure of an introduced inert gas is used, the first to the last de-peroxidation zone The selectivity of the cyclohexanone formation is so gas.
/ oncn, and this influence is all the more pronounced, ie the part emerging from the first zone is higher than the anti-peroxidation temperature. The choice peroxydierte oxidation product is continuously the number of Entperoxydierungszonen is therefore present in the second Entperoxydierungszone, optionally all, as a function of economic and techiiolo- out in the presence of a portion of the catalyst, determined in gischcn requirements that aim, v> of the remainder of the Hydroperoxide is again partially subjected to a reasonable hourly production with a non-de-peroxidation. Combine the work process into extensive apparatus. runs in this way up to the last peroxygenation zone, on For example, when working below its exit, the flowing mixture, which is practically free of hydroperoxide under the above-mentioned temperature conditions, is used according to the usual methods of adhesion ^; until secns successive zones. 45 drive to the separation of the cyclohexanone and cyclo-diesc depperoxidation zones can be treated in the verhcxanols. It can be used in different types of apparatus, which are usually worked up for spiclsvveise by distillation. In this combination of homogeneous phases of uniform convergence, the etite de-peroxidation zone can advantageously be used / filtration can be used. One halfway with the operation of distillation and can, for example, Umlaiifkolonnon, simple Colon - ■ Preconcentration can be combined. It is beneficial. which are equipped with a system for agitation that the hydroperoxide concentration of the solution are, or use autoclaves. It is expedient that enters the LCT / ito Entperoxydicriingszonn, low each of the zones nut means to connect that is, and is generally carried out so that at least enables the in the course of Entperoxydierung overall Ct) "; ₀ water formed on entry into the first zone has to be separated off, which is in the form of peroxides from the zone before the last deproxydicrogenation zone, as a binary acidic mixture with the cyclo-.

hexane, optionally with the simultaneous input The following examples illustrate the invention:

effect of an inert gas flow, can be removed. ". · \ -

The deproxy dehydration zones can advantageously- P

be arranged in a cascading manner. The apparatus used is shown schematically in FIG. 1

The catalysts that can be used are shown in Chromium Criva. It ravages three inlet columns Λ, B and C

te. which have a solubility in cyclohexane of at least stainless steel. Each of the cylindrical

0.1 g / l at room temperature. Under these columns (height 178 cm, inner diameter 5 cm), the

Soluble catalysts can be, for example, those with a coaxial inner cylinder (inner diameter carboxylic acids chromium (III) compounds, bcispids- 6j 3 cm), has a usable volume of 3.1 liters

wise naphthenate, octoate and stcarate, the car- and is given away with a turquoise coat, dci a

bonyIvcrbindungen.dieChclatformcn, diecarbonsauren contains at 123 ⁰ C held liquid medium. the

Chromium (VI) compounds, for example chromyl columns, are arranged in a cascade.

At the lower end of column A , a preconcentrated Cyelohexnnlösimg brought to 95 ° C. is introduced at 1 at a rate of 13.5 kg per hour. derived from the oxidation of Cyclohcxan with air without a catalyst and after dei concentration 10.8 "/" peroxides. 2:43 ⁰ Z _n cyclohexanol. l ° _'o cyclohexanone and 3:35 "/" high-boiling products, which mainly consist of acids and esters, contains.

At the lower end of each column, nitrogen is introduced in an amount of 100 liters per hour and a 0.03 ⁿ / ₀ solution of chromium octoate with a content of 10.8 percent by weight of metal in cyclohexane in an amount of 0.8 kg per hour for columns A and B and 0.48 kg per hour for column Γ.

Inside each column, the temperature is 115 "C and the pressure is 2.5 at.

The nitrogen and the products carried along (water, cyclohexane, cyclohexanol, cyclohexanone), emerging from the top of each of the columns, are fed to the condenser 4. The condensed products become the decanter 5 performed, which enables the separation of the water at 6 and the organic phase at 7, while the non-condensed gases are discharged at 8.

An overflow from the column C liquid phase is cooled to <0 ⁿ C, depressurized to atmospheric pressure and in counter-current at the same time with the separated by the decanter 5 organic phase in a column 9, which at 10 with an aqueous 8 / _o solution of ammonia ° with a flow rate of 4 kg per hour is fed, washed. The aqueous phase is removed at 11, while the organic phase is passed to a tray column D , which simultaneously ensures the decomposition of the remaining hydroperoxides and the removal of most of the cyclohexane.

This column is provided at its lower end with an evaporator that holds the liquid at its lower end at a temperature of 115 ⁰ C. The vaporized fraction (cyclohexane — water) is condensed at 13 and fed into a decanter 14 in which the cyclohexane is separated off at 15 and the aqueous phase at 16.

The mixture of high-boiling products is recovered at 17 and subjected to distillation.

In the following, for 100 kg of 1 supplied solution are those present in the various process stages Amounts of hydroperoxides. Cyclohexanol and cyclohexanone indicated.

treating solution Hydro Cyclo 1 Cyclo Output from A ... peroxides hexanone 4.21 hexanol Exit from B. . . kg kg 5.67 kg to Output from C ... 10.8 5.94 2.43 At the Exit from D .. 5.55 6.75 3.41 At the 2.43 3.80 At the 1.51 4.08 At the 0 3.76

Example 2

The apparatus used is shown schematically in FIG. 2 shown. It has three circulation columns A, B and C made of Ostfreiem Stahl. Each column with a cylindrical shape (height: 260 cm, inner diameter: 5 cm), which is equipped with a coaxial inner cylinder, inner diameter: 3 cm), has a useful volume of 3.1 liters and is provided with an outer jacket, ie a liquid kept at 105 "C Contains medium. The columns are arranged in a cascade.

At the lower end of column A , a cyclohexane solution brought to 100 ° C. is introduced at 1 mi at a rate of 9.64 kg per hour, which comes from the oxidation of cyclohexane with air in the presence of a catalyst and countercurrent washing with water (10 ° "Their weight) and dam

ίο has been subjected to drying by distilling off the azo-tropic mixture of water and cyclohexane. It contains 9.8 " ₀ hydroperoxides. 2.76", "Cyclohexanol. 1 cent, cyclohexanone and 1 ° / ₀ heavy products mainly consist of acids and esters at the lower end of each column is carried further at 2 nitrogen at a rate of 200 I per hour and at 3 a 0.825 ° "solution of tert .-Butyl chromate in cyclohexane at a rate of 0.312 kg per hour for each of the columns A.

B and C a.

Inside each column, the temperature is 105 ° C. and the pressure is 2.6 at. At the top of each column, the nitrogen and the products carried along (essentially water and cyclohexane) are condensed at 4.5 ° C. and the condensed products are condensed decanted at 7, 8 and 9, which enables the water to be separated off at 10, 11 and 12, while each of the organic phases is recycled at the lower end of the corresponding column. The non-condensed gases are removed at 13 after relaxation. The liquid phase which overflows from column C is let down to atmospheric pressure at the lower end of a tray column D; In this column, the remaining peroxides are decomposed and most of the cyclohexane is removed.

This column has a at its lower end

Evaporator on, which keeps ^{the liquid at 110 D C.} The vaporized fraction (cyclohexane-water) is condensed at 14 and then taken up by the decanter 15, in which the cyclohexane is separated off at 16 and the aqueous phase at 17.

The mixture of hardly volatile products will

obtained at 18 and subjected to a distillation.

In the following, for 100 kg of 1 supplied solution are those present in the various process stages Hydroperoxide quantities indicated:

Solution to be treated 9.8 kg

At the exit of A 4.33 kg

At the exit of B 1.66 kg

At the exit of C 0.53 kg

At the exit of D 0 kg

After 98 hours of continuous operation, an average hourly production of 764 g is obtained Cyclohexanone and 457 g cyclohexanol.

The comparison tests below show the advantage of the method of operation according to the invention the one known from the German Auslegeschrift 1 002 754, in the case of the decomposition of hydroperoxide on only one vessel is used.

Comparative experiments

a) The apparatus used consists of three cascades arranged autoclaves, which are equipped with an axial stirrer. It has a useful capacity of 4 liters and is provided with an outer jacket containing a liquid medium held at 92 " contains.

The first autoclave is brought into the first autoclave at one speed A cyclohexane solution at 21 kg / hour. those from the oxidation of cyclohexane with Air originates in the absence of a catalyst and then concentrated and washed with water would.

The solution introduced every hour contains 1175g Cyclohexyl hydroperoxide, 300 g cyclohexanol. 107 g of cyclohexanone and high-boiling products, mainly consist of acids and esters.

A solution of t-butyl chromate in cyclohexane is also poured into the first autoclave at a rate of 0.25 g of hydroperoxide introduced per kilogram.

Inside each autoclave the temperature is 91 ° and the pressure 0.4 at.

The vaporous products (water, cyclohexane) escaping from the top of each autoclave are sent to a condenser. The liquid phase overflowing from the third autoclave is cooled and then let down to atmospheric pressure. The withdrawals are carried out at regular intervals and so it is found that the liquid phase that escapes per hour. Contains 90 g of unreacted hydroperoxide, which corresponds to a degree of peroxide decomposition of 92 ⁿ _{/ 0} .

The solution flowing out every hour contains 745 g of cyclohexanone and 484 g of cyclohexanol.

b) For comparison purposes, the cascade of three autoclaves is replaced by a single autoclave with a useful capacity of 3.6 liters, equipped with an axial stirrer and a condensation device for vaporous products flowing out of the upper part of the autolkav. Otherwise will the same temperature and pressure conditions. as with the autoclaves under a), complied with.

The same cyclohexane solution is found in the upper part of the autoclave. as it was also used above, together with tert-butyl chromate in the same quantitative ratio brought in. The feed rate is 645 g per hour. In a continuous process one taps after one hour at the bottom of the autoclave

ao from a solution which contains 3.28 g of cyclohexyl hydroperoxide, 20.7 g of cyclohexanone and 2: 5.9 g of cyclohexanol. The unconverted amount of hydroperoxide corresponds to a degree of peroxide decomposition of 91 ⁰ Z ₀ .

1 sheet of drawings

109 582,413

• 918

Claims (1)

Claim: Process for the continuous production of mixtures of cyclohexanol and cyclohexanone, which are rich in cyclohexanone, by heating a solution of cyclohexyl hydroperoxide in Cyclohexane produced by the oxidation of Cyclolie.xan in the liquid phase with a molecular oxygen containing gas has been contained, in the liquid phase at a temperature between 80 and 150 C in the presence of a soluble chromium derivative as a catalyst, characterized in that that one works in several, but at least three consecutively arranged reaction zones, where within each individual zone the hydroperoxide concentration is maintained at a substantially uniform value at all locations.