MXPA97001632A - Procedure to obtain isofor - Google Patents

Abstract

The present invention refers to a process to obtain isophorone from acetone, characterized in that the operation is carried out (i) in the liquid phase in the presence of a magnesium-aluminum doubleoxide of the formula Mg1-xAlxO1 + xo (ii) either in the gas or liquid phase in the presence of a catalyst of the general formula (I): [(Mg2 +) 1-x (Al3 +) x (OH-) 2] x + [(OH-) x] x- (H2O) n with 0.20

Description

PROCEDURE TO OBTAIN ISOFORONñ DESCRIPTION The present invention relates to a new process for obtaining isophorone from acetone. Isophorone is used industrially as a solvent and is also an important synthesis intermediate, especially for the manufacture of 3,5-x-lenol. The self-condensation of acetone to isophorone can be carried out either in the liquid phase or in the vapor phase. The liquid phase process generally employs dilute solutions of potassium or sodium hydroxide as catalyst (GB 1 528 129, BE 611 719, US 2 399 976, FR 1 506 158). However, it is + e procedure has many disadvantages. The catadores are not very selective. Only a portion of the catalysts are recirculated after the sedimentation and separation of the isophorone. The other portion, not recirculated, is neutralized with sulfuric acid and consequently produces salts, which removal, necessary for the environment, is expensive. In addition, the self-condensation of acetone in the vapor phase is carried out at an elevated temperature, generally higher than 200 ° C and in the presence of basic catalysts such as magnesium or aluminum oxides (KV, Ram Narnurthy et al., Proc. 8th Nat. Symp. Catal., Sindp, India 12-14 Feb. 1987, p.649) and mixed oxides based on magnesium and aluminum (EP 640 387 US 4 970 191). The disadvantages of this vapor phase reaction are numerous. Therefore, the preparation of the catalysts is poorly reproducible and their formation, to avoid diffusion phenomena, is not very easy (US 5 153 166). In addition, the life time of these catalysts is induced by the deposition of coke on the surface, which is achieved by means of heavy non-recirculating byproducts. A new process for obtaining isophorone from acetone has now been found, which has the advantage of the ability to employ existing plants operating in the liquid phase, however, without showing the aforementioned disadvantages. This process is characterized in that the operation is carried out in liquid phase in the presence of double magnesium-aluminum oxide of the formula Mg? - > ? fll? O? +? or either in gaseous or liquid phase in the presence of a catalyst of the general formula (I): prig2 +)? - "(013 + j" (OH-) 2] * + C (OH-) "] * - (H2O ) "(I) with 0.20 <x < 0.33 yn < 1. The double magnesium-aluminum oxide tlgi-xPllx 0? + X, which has a value of x that can be from 0.2 to 0.33 can be a commercial product or may be obtained by any known conventional methods for inorganic chemicals, such as, for example, by calcining hydrotalcites at a temperature below 800 ° C. Advantageously, a commercial double oxide is used and preferably that of the Japanese Company. Kyo a, reference KU 2000, which has a value of x close to 0.3.The catalyst of the general formula (T) has a laminar structure similar to that of hydrotalci-a, in the same way as the hydrotalcite, natural, this catalyst is composed of positively charged layers of brucite type, of the formula CMgi-xPlJx (0H) 23 with 0.2 <x < 0.33 and of interlayers that consist of hydroxy OH- and water molecules. The catalyst of the general formula (T) having a value of n that can vary from 0.5 to 0.75 is preferably used. Advantageously, a catalyst of general formula (I) in which case the value of n is equal to or close to 0.81-x, is chosen for the autocondensation reaction of acetone to isophorone, especially rneixnepta of the formula: C (Mg2 +) 07s ( fil3 +) 0.25 < 0H-) ~ 23 ° • 25+ í (OH ") 0.25 J ° • 25 (H20) 0.S The catalyst of the general formula (I) can be prepared following the method described by G. Mascolo and 0. Marino en Mmeralogical Magazine, March 1980, vol 43 page 619. This method of preparation consists of suspending geJ of alumina and MgO, obtained by the calcination of basic magnesium carbonate at 650 ° C, in distilled water in a closed Teflon receptacle with agitation, for one week at 80 ± 1 ° C. The suspension is then filtered in the absence of C02 and finally the collected solid is dried over silica gel. This catalyst can also be prepared by hydration of a double magnesium-aluminum oxide in the absence of C02. The hydration is carried out with water, either in the liquid phase or in the vapor phase. The double mixed oxide can be a commercial product or the product obtained by the calcination of hydrotalcites having a value of x that can vary from 0.2 to 0.33. After the hydration step according to any of the methods described above, the solid may be dried either by evaporation under reduced pressure at a temperature below 60 ° 0 or by rinsing with a water-irascible solvent, for example acetone. To prepare the catalyst of the general formula (T), a commercial double oxide is advantageously chosen, and preferably the same as that referred to above. In most cases, the double oxide is hydrated in the aqueous phase and the solid thus obtained is advantageously rinsed with a solvent miscible with water and preferably with acetone. Although the catalyst of the general formula (I) can be used in the autocondensation reaction of acetone to isophorone in the vapor phase, it is preferred to use it in the reaction in the liquid phase. The process for obtaining isophorone from acetone according to the present invention can be carried out continuously or in non-continuous form.

Industrial, it is preferred to operate continuously. When operating continuously, the catalyst can be placed in a stationary bed through which liquid acetone passes, or it can be brought into contact with liquid acetone in a stirred bed. Regardless of the form of operation, (continuous or not continuous) the pressure must be sufficient to keep the acetone in liquid phase at the autocondensation temperature. A temperature of between about 100 ° C and about 250 ° C is what is generally used, and in most cases a temperature between about 110 ° C and approximately 220 ° C. During non-continuous operation, the reaction period may vary from 30 minutes to 8 hours and preferably 1 hour to 4 hours. However, a longer reaction period of 8 hours does not constitute a separation from the scope of the present invention. At the end of the reaction, isophorone is separated from the by-products by conventional techniques (distillation, sedimentation). The by-products including essentially rhinositiioxide, diacetone alcohol and C 2 and Cis compounds can be recirculated and therefore used. The invention will be better understood from the following examples: I) Experimental part 1) Preparation of the catalyst The double mixed oxide K) 2000 having the following characteristics is hydrated with water in the liquid phase: Chemical formula: 4.5MgO-Al2? 3 (x = 0.3077) Apparent density: 44 rnl / 10 g Appearance: fine white powder odorless BET = 172 rn2 / g Average particle size 70μrn Absorption property: absorbs at most 70-80 parts of water per 100 parts of KU 2000. 6 grams of K l 2000 are added from this stirring with 200 ml of decarbonated water (water with ions exchanged and then boiled). The mixture is allowed to stir for 3 hours and the solid is then separated. The isolated solid is then raised a number of times with acetone before being stored in the absence of C02. 9 g of solid are obtained from the general formula (T) where x has a value of 0. 3077, and having a crystal structure of the hydrotalcite or the type of rneixnep a. 2) Catalyst test General procedure. Approximately 50 to 200 g of acetone and a quantity of solid catalyst of between 1 g to 10 g are introduced at room temperature in a stirred 0.5 liter autoclave with a thermostat. Next, the autoclave is closed and then purged with hydrogen and optionally a nitrogen pressure of up to about 20 bar can be applied, stirring is started to stir at a rate of about 500 to 1500 revolutions per minute. The mixture is heated immediately to a temperature between 110 ° C and 220 ° C for a period that varies from 30 minutes to? hours. The temperature is then maintained for a period of between 1 hour and 4 hours. At the end of the reaction the autoclave is cooled rapidly for approximately 5 to 10 minutes with the aid of water circulation. After cooling, the autoclave is opened and the catalyst is separated from the final solution simply by filtration or sedimentation. The final solution containing acetone, diacetone alcohol, mesityl oxide, isophorone and compounds of C12 and Cis is then analyzed with the help of gas phase chromatography.

Chromatographic conditions A Hewlett-Pac rd 5710 chromatograph equipped with an HP1 column 30 rn in length and 0.3 mm in diameter. The temperature of the injector is 150 ° C and the temperature of the FTD detector is 200 ° C. The oven is programmed to maintain its temperature at 60 ° C for 6 minutes and then to increase its temperature at a heating rate of 8 ° C per minute until 250 ° 0 is reached. The conversion of acetone is defined by the following formula: 100xC (No. of moles of acetone) 0 - (No. of moles of aceton) f (No. of moles of acetone) 0 with (number of moles of acetone) 0 = number of moles of acetone introduced into the reactor, - (number of moles of acetone) f = number of moles of acetone remaining at the end of the reaction The selectivity for isophorone is defined by the following formula: 300? [(number of moles of i fo) f 3 (number of moles of acetone) 0 - (number of moles of acetone) f with (number of moles of ifo) f = number of moles of isophorone formed at the end of the reaction. 3) Examples EXAMPLE 1 3 g of catalyst KU 2000 and 100 g of acetone are introduced at room temperature in a stirred 0.5 liter autoclave with thermostat. The autoclave is closed and then purged with nitrogen and agitated. The mixture is then heated for one hour at a temperature of 150 ° C at a stirring speed of 100 revolutions per minute. The stirred mixture is maintained at 150 ° C for one hour and the pressure of the reaction mixture is then about 10 bar. At the end of a one hour reaction at 150 ° C the autoclave is cooled for 5 minutes with the help of water circulation. The cooled autoclave is then opened and the catalyst is separated from the final mixture simply by filtration. The composition of the final solution is determined with the aid of gas phase chromatography. The final mixture is composed, in percent by mass, of Acetone 75 Rnesityl oxide 9 Diacetone alcohol 3 Isophorone 7.3 C 2 2 compounds Cis 0.8 compounds Unidentified compounds 3.9 + water This corresponds to an acetone conversion of 25 % and a selectivity of 37% for isophorone. The total selectivity for C? 2, rnesityl oxide, diacetone alcohol and isophorone is 97%.

EXAMPLE 2 The operation is as in Example 1, except that 6 g of KU 2000 are used instead of 3 g of KU 2000. The final composition of the mixture after a reaction of 1 hour is reported in table 1. A conversion is obtained. n of acetone of 30% and a selectivity of isophorone of 45%.

EXAMPLE 3 The procedure is identical to that of Example 1, except that the autoclave is maintained at 180 ° C for 1 hour and the pressure of the reaction mixture is 18 bar. The final composition of the mixture after a reaction of one hour at 180 ° C is reported in Table 1. An acetone conversion of 35.5% and a selectivity to 47% isophorone is obtained.

EXAMPLE 4 The procedure is identical to that of Example 1, except that 102 g of acetone are introduced instead of 100 g and the autoclave is maintained at 200 ° C instead of 150 ° C. The pressure of the reaction mixture is 25 bar. The final composition is listed in Table 1 and corresponds to a conversion of acetone of 37% and a selectivity to isophorone of 18%.

EXAMPLE 5 The procedure is identical to that of Example 3, except that a catalyst that has already been operated under the same experimental conditions is employed. The composition of the final solution is reported in Table 1. An acetone conversion of 32% and a selectivity to 45% isophorone is obtained.

EXAMPLE 6 The process is identical to that of Example 4, except that 3 g of hydrated and rinsed catalyst according to the method described 1.1) are used in place of a KU 2000 catalyst. 105 g of acetone are also introduced instead of 102 g. The composition of the final solution is reported in table 1. A composition of acetone 38% and a selectivity to isophorone of 51% is obtained.

EXAMPLE 7 The procedure is identical to that of Example 6, except that the temperature is maintained at 120 ° C for 4 hours instead of 200 ° C for 1 hour. 104 g of acetone are also introduced into the reactor instead of 105 g. The composition of the final solution is reported in Table 1. A conversion of acetone of 25% and a selectivity to isophorone of 24% is obtained.

EXAMPLE 8 The procedure is identical to that of Example 7, except that the autoclave is maintained at a temperature of 150 ° C instead of 12 ° C and that 103 g of ketone are introduced instead of 104 g. The composition of the final solution is reported in Table 1. An acetone conversion of 31% and a selectivity to 45% isophorone are obtained.

EXAMPLE 9 (COMPARATIVE) The procedure is identical to that of Example 3, except that 106 g of acetone are introduced instead of 100 g and 10 g of water is added to the autoclave. The final composition is reported in table 1. An acetone conversion of 11% and a selectivity to 45% isophorone is obtained.

EXAMPLE 10 The procedure is identical to that of Example 1, but the catalyst hydrated and rinsed according to the method described in 1.1 is introduced in place of KU 2000. After a reaction of 1 hour at 150 ° C an acetone conversion of 27 is obtained. % and a selectivity for 48% isophorone. Under identical experimental conditions, the double oxygen is less selective than the hydrated catalyst of the general formula (I). cp Picture

Claims (5)

NOVELTY OF THE INVENTION CLAIMS

1. - A process for obtaining isophorone from acetone, characterized in that the operation is carried out (i) in liquid phase in the presence of a double magnesium-aluminum oxide of the formula Mg? -? Al? O? +? or (n) either in the gaseous or liquid phase in the presence of a catalyst of the general formula (I): l "(Mg2 +)? -? (A13 +)? (OH-) 2 x + r (OH-)? x - (H20) "(I) with 0.20 <x < 0.33 yn < 1. 2.- A procedure in accordance with claim 1, further characterized because the value of n is between 0.5 and 0.75, the limits included 3. A method according to claim 1 or 2, further characterized in that the value of n is close to or equal to 0.81-x 4. A method according to any of claims 3, further characterized in that the Operation is carried out in liquid phase at a temperature of between 100 ° and 250 ° 5. A process according to claim 4, further characterized in that the temperature is between 110 ° C and 220 ° C.