KR20040072433A - Method for the effective preparation of 1-cyclohexyl-1-ethanol - Google Patents

Abstract

PURPOSE: Provided is a process for producing 1-cyclohexyl-1-ethanol in high efficiency and high yield by a continuous hydrogenation under a comparative mild condition, which can minimize a side reaction without adding a metal salt. CONSTITUTION: The process for producing the 1-cyclohexyl-1-ethanol comprises the steps of: preparing a catalyst by supporting 1-5wt%(based on the weight of the catalyst) of ruthenium to a silica support having an acid activity index of less than 10%; filling a reactor with the catalyst and flowing hydrogen and injecting and continuously hydrogenating 1-methyl benzyl alcohol and/or acetophenone as a raw material at 50-170deg.C and 10-100kg/cm¬2, wherein the raw material is mixed with the produced 1-cyclohexyl-1-ethanol as a diluent in the ratio of 80:20-20:80.

Description

Method for the preparation of high efficiency 1-cyclohexyl-1-ethanol {Method for the effective preparation of 1-cyclohexyl-1-ethanol}

The present invention relates to a method for preparing high-efficiency 1-cyclohexyl-1-ethanol, and more particularly, using a catalyst prepared by dispersing and carrying 1 to 5 weight% of ruthenium on a silica support having an acid strength index of 10% or less. A portion of 1-cyclohexyl-1-ethanol, a reaction product, is mixed with diluent 1-methylbenzyl alcohol and / or acetophenone as a diluent, diluted, and then continuously hydrogenated to yield high yield and high efficiency. A method for producing cyclohexyl-1-ethanol.

1-cyclohexyl-1-ethanol (hereinafter referred to as CHEA) is used to prepare vinylcyclohexane through dehydration and vinylcyclohexane is a useful material as a polymer material.

CHEA has been mainly produced by hydrogenation of 1-methylbenzyl alcohol or acetophenone using a metal supported catalyst such as ruthenium. The main problem in this reaction is the low yield of CHEA due to by-products such as ethylcyclohexane produced during the reaction.

U.S. Patent No. 3,366,695 describes a method of reacting by adding a basic metal aqueous solution to 1-methylbenzyl alcohol as a raw material for hydrogenation to suppress side reactions, but it is necessary to remove the basic metal from the CHEA obtained after the reaction. There is a problem. In addition, U.S. Patent No. 4,695,660 describes a method for producing CHEA from acetophenone with a high yield using a catalyst prepared by supporting 0.1-1% by weight of ruthenium on alumina or silica. Because the reaction must be carried out at 350 atm), it is not only limited to using an expensive high-pressure reactor, but also has a disadvantage in that the manufacturing cost is increased such that more than 21 times more hydrogen is added than the number of moles of acetophenone added. In addition, US Pat. No. 6,018,048 describes a method for preparing CHEA from 1-methylbenzyl alcohol using Raney-ruthenium type catalyst (Example 8), but the weight of 1-methylbenzyl alcohol treated by the catalyst is 40 As the weight% and the reaction by adding water and methanol together, the catalyst cost is high, and there is a problem that CHEA must be separated from the complex reaction mixture after the reaction.

In conclusion, using the prior art is difficult to manufacture CHEA at low cost and high efficiency.

Therefore, an object of the present invention is to minimize the side reactions without the addition of metal salts to maximize the reaction yield and to find a condition that can be hydrogenated continuously in a relatively mild condition to reduce the manufacturing cost, more economical than the prior art, The present invention provides a method for preparing CHEA in an efficient manner.

In order to achieve the above object, a method for preparing high-efficiency 1-cyclohexyl-1-ethanol according to the present invention includes preparing a catalyst by supporting ruthenium on a silica support having an acid activity index of 10% or less; And a step of continuously hydrogenating the catalyst by charging 1-methylbenzyl alcohol and / or acetophenone under a reaction condition of 50 to 170 ° C. and 10 to 100 kg / cm ² while feeding hydrogen into the reactor. .

Hereinafter, the present invention will be described in more detail.

As in the above-described prior art, when a basic metal salt or another basic organic compound is added to the reaction raw material and reacted, there is a problem that a separation step is required after the reaction. This had a lot of trouble. Accordingly, the present invention provides a method for producing 1-cyclohexyl-1-ethanol with high efficiency that can reduce the production cost by maximizing the reaction yield by minimizing side reactions without the addition of metal salts and continuously hydrogenating under relatively mild conditions. It is about.

Generally, metals such as palladium, platinum, nickel, ruthenium, and rhodium are used in the catalyst used in the hydrogenation reaction of the Group VIII metal of the periodic table. As a result of the study of the present inventors, it is economical to use ruthenium rather than expensive rhodium, although the yield of CHEA is high, especially when rhodium and ruthenium are used for hydrogenation of 1-methylbenzyl alcohol and / or acetophenone. Example 8 of US Pat. No. 6,018,048 describes the use of ruthenium metal itself as a catalyst, but it was more economical to use the metal evenly dispersed / supported on a support. The support uses a large surface area to disperse the metal widely and improve physical properties such as thermal and mechanical stability that are difficult to obtain only with the metal.

Looking at the reaction mechanism of hydrogenation reaction of 1-methylbenzyl alcohol and / or acetophenone in order to determine the cause of the decrease in the reaction yield in the preparation of CHEA using a ruthenium catalyst, the acetophenone is hydrogenated 1-methylbenzyl alcohol When dehydrated before 1-methylbenzyl alcohol is hydrogenated, ethylbenzene is produced, and when ethylbenzene is hydrogenated, ethylcyclohexane is produced. When 1-methylbenzyl alcohol is not dehydrated and hydrogenated, a target CHEA is produced, but when CHEA is dehydrated, ethylcyclohexane is produced. That is, both side reactions, ethylbenzene and ethylcyclohexane, were produced by dehydration during the hydrogenation reaction, and these side reactions were found to be related to the acid strength of the catalyst support itself. That is, as the acid strength of the catalyst support increases, the dehydration reaction is promoted during the hydrogenation reaction, thereby lowering the reaction yield of CHEA.

Dehydration is one of the typical acid catalyzed reactions (The chemistry of catalytic hydrocarbon conversions, Herman Pines, Acedemic press, 2-3 pages, 1981). It is a well-known fact that it has a (introduction to catalysts, transfer system, Hallymwon, 1992). Therefore, the use of these solid acids as a support causes a dehydration reaction due to the acid function during the hydrogenation reaction.

Therefore, in order to suppress dehydration and increase the yield of CHEA without adding basic metal salts or other organic compounds to the reactants, it is important to select a support having a weak acid strength and carry ruthenium thereon. However, in the prior art it is difficult to find an example which mentions the importance of the acid strength of the support.

There are several methods for indicating the acid strength of a solid acid, but the present inventors evaluated the acid strength of the support by applying the acid activity index evaluation method mentioned in US Pat. No. 5,773,677. To illustrate the method briefly, 1 g of catalyst was placed in a fixed bed reactor and a gas consisting of 5 vol% 2-propanol and 95 vol% helium was passed. At this time, the flow rate of helium through the reactor is at a rate of 50 ml per minute. In US Pat. No. 5,773,677, the acid strength index was defined as the conversion rate of 2-propanol when the reaction was carried out at 250 ° C., but according to the researches of the present inventors, most of except for silica when the temperature was about 250 ° C. Since the acid strength index of the solid acid is not more than 100%, the acid strength index used in the present invention is defined as the rate at which 2-propanol is converted when reacted at 200 ° C. Based on the results of this experiment, it was found that the acid strength index of some silicas was very low, less than 10%.

In some prior arts, alumina, etc., used as a support, had an acid strength index of 90% or more when evaluated by the aforementioned method, and the catalyst using a strong acid strength had a lot of side reactions due to dehydration in the CHEA hydrogenation reaction. . However, even if silica contains only a small amount of impurities such as aluminum and zirconium, the acid strength is greatly increased, so that the dehydration reaction during the hydrogenation reaction can be suppressed only by using silica having an acid strength index of less than 10%.

Silica that can be used as a support in the present invention is a support without particular limitation as long as any of the natural silica, synthetic silica, silica gel, pyrogenic silica (trade name; aerosil, carbosil) is 10% or less of the acid strength index Can be used as It is preferable that the surface area of the silica used as a support body is 100-400 m <^2> / g.

In addition, the content of ruthenium supported on the support was adjusted to produce CHEA at a relatively low production cost in a continuous reactor having high reaction efficiency using the catalyst of the present invention. Increasing the ruthenium content to 1 to 5% by weight of the total catalyst weight gives CHEA with high efficiency even under mild reaction conditions of less than 100 atmospheres. In this case, when the total catalyst weight is less than 1% by weight, the reaction efficiency is low, and the conversion rate of 1-methylbenzyl alcohol can be increased only by applying harsh reaction conditions such as high temperature or high pressure of 200 kg / cm ² or more.

In addition, at a low pressure of 100 atm or less, since the amount of hydrogen introduced for maintaining the pressure is less than 5 mole times compared to the number of moles of 1-methylbenzyl alcohol, the economics in the manufacturing process can be further improved. In the continuous reaction, even though a catalyst having a ruthenium content of 1 to 5% by weight does not consume the catalyst during the reaction, and a deterioration in reactivity is hardly observed even after long use, a catalyst having a ruthenium content of less than 1% by weight is used. In comparison, the economics of the reaction are not significantly affected.

Meanwhile, the ruthenium catalyst which can be used in the present invention is prepared by dissolving ruthenium in a salt state in water and then supporting it on silica by a generally known method. The catalyst carrying the ruthenium salt is calcined in the air at 300-600 ° C. to decompose the salt and then stored. The catalyst is used after reducing to 100-500 ° C. in a reducing agent atmosphere such as hydrogen before the reaction. Ruthenium salts used in the preparation of catalysts include ruthenium chloride, ruthenium nitrosylnitrate, ruthenium acetylacetonate, and the like, and there are no particular restrictions on the salt form.

In the present invention, the ruthenium catalyst is used in an amount of 0.01 to 0.5% by weight based on the ratio of metal ruthenium to 1-methylbenzyl alcohol and / or acetophenone as a reaction raw material, and the shape of the catalyst is not particularly limited.

Meanwhile, the hydrogenation of 1-methylbenzyl alcohol is a severe exothermic reaction. For example, when the weight hourly space velocity at which the CHEA is introduced into the reactor is 1 at a reaction temperature of 120 ° C., it is observed that the temperature of the catalyst layer is locally increased to 250 ° C. due to the exothermic reaction.

Therefore, in the case of increasing the weight space velocity into which the reaction raw materials are injected in order to increase the efficiency of the process in the continuous hydrogenation reaction, the catalyst performance is lowered due to the rapid exotherm on the surface of the catalyst and the yield of CHEA is lowered. In order to prevent such rapid heat generation, a double tube type reactor may be used, but it is not suitable for a large-scale reactor.

Therefore, in the present invention, a method of mixing a part of the CHEA produced according to the present invention with the reaction raw material as a diluent is applied in order to prevent exothermic heat of the catalyst and increase the feed rate of the reaction raw material to further increase the production efficiency. When the raw material is diluted in this way, the diluent buffers the reaction heat generated, thereby suppressing the rapid temperature increase and further increasing the feed rate of the raw material. In addition, by using the reaction product CHEA as a diluent, it is more economical to eliminate the process of separating the diluent from the reaction product. As such, an example of reacting a part of a reaction product by mixing with a reaction raw material has been known in the past, but since CHEA may be dehydrated by an additional reaction to decrease the reaction yield, a catalyst having an extremely low acid strength as in the present invention is not used. It is not possible to use CHEA as a diluent.

In other words, as described above, the present invention selects silica having an acid strength index of less than 10% as a catalyst support, which is easy to be applied to commercial processes because it has high mechanical strength and can withstand high temperature firing without acid function. It is prepared to adjust the content of ruthenium metal supported on the support to 1 to 5% by weight, thereby minimizing dehydration reaction due to acid catalysis without adding basic metal salts or other basic organic compounds to the reactants. CHEA can be prepared in high yields. It may also react in mild reaction conditions of up to 100 kg / cm ² . In addition, by mixing a part of the prepared CHEA with the hydrogenation reaction raw material as a diluent to prevent the catalyst damage and yield decrease due to the exothermic during the reaction can increase the weight space velocity of the raw material introduced.

On the other hand, the reaction raw materials used to prepare the CHEA in the present invention is 1-methylbenzyl alcohol, acetophenone or a mixture thereof, and there is no limitation in the mixing ratio when using the mixture.

Moreover, it is preferable to carry out the conditions for hydrogenating the reaction raw material of 1-methylbenzyl alcohol and / or acetophenone using the said catalyst system within the reaction temperature of 50-170 degreeC, and the reaction pressure of 10-100 kg / cm <^2> . . If the reaction temperature is less than 50 ℃ the reaction rate is slow, if it exceeds 170 ℃ yield is reduced due to increased side reactions. In addition, if the reaction pressure is less than 10kg / cm ² it is difficult to occur the reaction, and if it exceeds 100kg / cm ^{2 the} process cost is reduced due to the increase in the equipment cost by using a high pressure.

On the other hand, the weight space velocity of the reaction raw material to the weight of the catalyst is determined by the 0.5~5h ^-1 range, the economy of the process since a long time to complete if the unit is less than 0.5h ^-1 CHEA production is reduced, the 5h ^-1 If exceeded, there is a disadvantage that the reaction does not occur sufficiently.

In addition, although the flow rate of hydrogen introduced in the reaction varies depending on the reaction raw material and the feed rate of the raw material, 4 mole times of 1-methylbenzyl alcohol as the raw material, and acetophenone when the acetophenone is used as the raw material. 5.2 mole times or more is enough. In addition, the mixing ratio of 1-methylbenzyl alcohol and the reaction product CHEA which is a diluent to be added to the reactor is determined in the range of 80:20 to 20:80. If the mixing ratio of the diluent is less than 20%, it is difficult to expect the effect of dilution, and if the mixing ratio exceeds 80%, the time required for the production of unit CHEA will be longer, thereby reducing the economic efficiency of the process.

The reaction type is particularly preferably continuous reaction using a tubular fixed bed reactor in view of operating costs, but can also be carried out in a batch reaction type. In the case of the continuous reaction using the tubular fixed bed reactor, it is preferable to use the catalyst by forming a suitable size according to the length and diameter of the reactor, and in the case of a batch reaction, it is preferable to use a catalyst in the form of a powder.

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited thereto.

Example 1

1 g of silica in a 2 mm pellet form was charged into a fixed bed reactor and reacted with a gas of 5 vol% 2-propanol and 95 vol% helium at a temperature of 200 ° C. at a rate of 52.6 ml per minute. In such a reaction, ruthenium chloride was loaded in a pellet-type silica having an acid strength index of 10% or less defined as the conversion rate of 2-propanol so that ruthenium was 2% by weight, dried at 110 ° C for 6 hours, and then dried at 500 ° C. The catalyst was prepared by firing at 5 hours. After filling a catalyst prepared in a stainless steel tubular reactor having a diameter of 10 mm and having a capacity of 80 cc, hydrogen was charged at a rate of 20 cc per minute, and the temperature was raised to 350 ° C. to perform reduction. After the reduction, the amount of hydrogen was adjusted to be 4 mole times of 1-methylbenzyl alcohol, and the reactor temperature was 120 ° C. and the reaction pressure was 80 kg / cm ² , followed by a weight space velocity of 1 h ^-1 (1-methylbenzyl alcohol). The reaction was started by adding the reaction raw materials). As a reaction material, a mixture of 98% purity 1-methylbenzyl alcohol and CHEA in a weight ratio of 50:50 was used, and the reaction product was analyzed by gas chromatography equipped with a flame ionization detector. For 40 hours after the reaction, the average conversion of 1-methylbenzyl alcohol was 100% and the average selectivity of CHEA was 97.5%. Thereafter, no activity deterioration was observed until 2000 hours.

Example 2

The same catalyst as in Example 1 was charged to the same reactor, and then the reduction was carried out in the same manner. After the reduction, the amount of hydrogen was adjusted to 5.5 times that of acetophenone, the reactor temperature was 120 ° C., the reaction pressure was 80 kg / cm ² , and the reaction raw material was continued at a weight space velocity of 1.5 h ⁻¹ (based on acetophenone). The reaction was started with input. As a reaction material, a mixture of 99% pure acetophenone and CHEA in a weight ratio of 50:50 was used, and the reaction product was analyzed by gas chromatography equipped with a flame ionization detector. For 40 hours after the reaction, the average conversion of acetophenone was 100% and the average selectivity of CHEA was 98.2%.

Comparative Examples 1 and 2

The reaction was carried out in the same manner as in Example 1, except that a catalyst prepared by supporting ruthenium to 2 weight% on different supports (silica A and silica B) having an acid strength index of 95.1 and 100, respectively, was used. The acid strength of the catalyst support and the results of the reaction experiments are summarized in Table 1 below.

Comparative Example 3

The reaction was carried out in the same manner as in Example 1, except that a catalyst prepared by loading ruthenium to 2% by weight of alumina (SA3177), a commercial product of Norton, was used. The results are summarized in Table 1 below.

Support Mountain strength index,% Reaction yield,% Comparative Example 1 Silica A 95.1 85.3 Comparative Example 2 Silica B 100 80.4 Comparative Example 3 SA3177 100 76.8

As can be seen from the above examples and comparative examples, the preparation method according to the present invention can minimize the dehydration reaction due to the acid catalysis without adding a basic metal salt or other basic organic compound to the reactant, so that the CHEA is high. It can be produced in a yield and can react in mild reaction conditions of 100kg / cm ² or less, as well as increase the processing speed of the raw materials without damaging the catalyst and yields due to exothermic heat during the reaction can be produced efficiently and economically can do.

Claims (6)

Preparing a catalyst by supporting ruthenium on a silica support having an acid activity index of 10% or less; And Charging the catalyst to a reactor and then continuously hydrogenating the reaction raw material of 1-methylbenzyl alcohol and / or acetophenone under a reaction condition of 50 to 170 ° C. and 10 to 100 kg / cm ² while supplying hydrogen; Method for producing a high efficiency 1-cyclohexyl-1-ethanol comprising a. The high efficiency of claim 1, wherein the acid strength index of the silica support is defined as the conversion rate of 2-propanol when a gas composed of 5% by volume 2-propanol and 95% by volume helium is passed at 200 ° C. Method for producing 1-cyclohexyl-1-ethanol. The method for producing high-efficiency 1-cyclohexyl-1-ethanol according to claim 1, wherein the amount of ruthenium supported on the silica support is 1 to 5 weight% of the weight of the catalyst. The method for producing high-efficiency 1-cyclohexyl-1-ethanol according to claim 1, wherein the amount of the catalyst used is 0.01 to 0.5% by weight based on the ratio of metal ruthenium to the reaction raw material. The method of claim 1, wherein the weight space velocity of the reaction raw material is 0.5 to 5 h ⁻¹ based on the weight of the catalyst. According to claim 1, wherein the reaction raw material is added to the step of the continuous hydrogenation of the reaction raw material is a diluent of 1-cyclohexyl-1-ethanol reaction product is diluted to a mixing ratio of 80:20 ~ 20:80 The manufacturing method of high-efficiency 1-cyclohexyl-1- ethanol which is used.