KR20040027046A - Method for disposing of carbontetrachloride - Google Patents

Abstract

PURPOSE: A method for treating carbon tetrachloride is provided, to convert carbon tetrachloride into unharmful materials with producing useful by-products as well as improved conversion rate of carbon tetrachloride and selectivity of chloroform and low deactivation of a catalyst. CONSTITUTION: The method comprises the steps of mixing carbon tetrachloride with an aliphatic alcohol to obtain a carbon tetrachloride-alcohol mixture solution; and carrying out hydrodechlorination of the mixture solution in the presence of a catalyst at a temperature of 298-353 K to produce at least one selected from the group consisting of an acetal, aldehyde, alkyl vinyl ether and dialkyl carbonate and chloroform. Preferably the aliphatic alcohol is an aliphatic alcohol of C1-C4; and the catalyst is at least one metal selected from the group consisting of platinum, palladium and ruthenium. Preferably the catalyst is supported into or ion exchanged with at least one carrier selected from the group consisting of montmorillonite, activated carbon, MCM (Mobil Composition of Matter), SiO2, Al2O3, SiO2-Al2O3 and zeolite.

Description

Method for disposing of carbon tetrachloride {Method for disposing of carbontetrachloride}

The present invention relates to a method for treating carbon tetrachloride, and more particularly, to a method for treating carbon tetrachloride by converting carbon tetrachloride to a harmless substance.

Carbon tetrachloride and its chlorinated hydrocarbons are known to be the major causes of ozone depletion. These removal methods generally include a method by direct thermal combustion, a catalytic combustion method using a catalyst, and a catalytic hydrodechlorination method using a catalyst.

The method by direct pyrolysis requires excessive energy due to the reaction at a high temperature of 1173 K or more, and has a disadvantage of generating by-products such as dioxin having high toxicity.

The pyrolysis method using a catalyst is performed at a high temperature of 723 K or more, and since toxic phosgene (phosgen) is generated from carbon monoxide and chlorine gas generated by incomplete combustion, there is a problem in that complete combustion is required.

The dechlorination method using a catalyst uses a platinum-based catalyst which is commonly used for hydrogenation, and the reaction takes place at a low temperature of 373-473K, resulting in low energy consumption and generation of secondary pollution as a reaction product. Instead, it has the advantage of obtaining useful products methyl chloride, methylene chloride, chloroform, methane and the like.

Recently, a study on the commercialization process of carbon tetrachloride treatment method using a dechlorination reaction using a catalyst has been competitively conducted, and according to US Patent No. 5,721,189 of Akzo Nobel, the 0.3% Pt / Al ₂ O ₃ catalyst was replaced with NH ₄ Cl. After treatment, the reaction temperature was 363K, reaction pressure 5atm, and space reaction 1500 liter / kg / hour, but the reaction was performed for 2000 hours without any deactivation of the catalyst. A catalytic reaction system exhibiting excellent activity is disclosed.

However, while the dehydrogenation reaction using the catalyst in the gas phase is excellent in terms of the conversion rate of carbon tetrachloride and selectivity to chloroform, the deactivation of the catalyst is rapidly progressed by the heat of reaction generated during the reaction, which makes it difficult to introduce a commercial process.

In order to overcome this problem of gas phase reaction, carbon tetrachloride is treated in the liquid phase by dehydrogenation in the absence of solvent (W091-09827, ERCROS, Spain) as a catalyst on which palladium, platinum, rhodium and the like are supported. 85% conversion of carbon tetrachloride and 85% selectivity of chloroform have been reported. In addition, Gomez-Sainero et al. Showed the highest reactivity in the catalyst supported on activated carbon among the various carriers carrying palladium in the liquid dehydrogenation reaction of carbon tetrachloride itself in the absence of solvent, and the selectivity to chloroform was 96 In percent (Ind. Eng. Chem. Res. 39, (2000) 2849).

It is an object of the present invention to provide an economical method for treating carbon tetrachloride, which has low deactivation of a catalyst, high conversion rate of carbon tetrachloride and high selectivity of chloroform, and which can produce beneficial by-products after carbon tetrachloride treatment.

1 is a scheme showing a representative product distribution by the reaction of carbon tetrachloride and ethanol.

Figure 2 is a graph showing the distribution of the product distribution by the conversion of carbon tetrachloride and ethanol over time on the Pd / Mont catalyst.

In order to achieve the above object, the present invention

Mixing carbon tetrachloride with an aliphatic alcohol to obtain a carbon tetrachloride-alcohol mixed solution;

Dehydrochlorination of the carbon tetrachloride-alcohol mixed solution in the presence of a catalyst at a temperature of 298K to 353K to produce at least one selected from the group consisting of acetal, aldehyde, alkylvinyl ether and dialkyl carbonate and chloroform. Provide a treatment method.

It is preferable that the aliphatic alcohol is a C ₁ to C ₄ aliphatic alcohol.

The catalyst is preferably at least one metal selected from the group consisting of platinum, palladium, and ruthenium.

The catalyst is at least one selected from the group consisting of montmorillonite, activated carbon, Mobil Composition of Matter (MCM), SiO ₂ , Al ₂ O ₃ , SiO ₂ -Al ₂ O ₃ , or zeolite It is more preferable that it is supported or ion exchanged on the carrier of.

The amount of the metal catalyst supported or ion exchanged on the carrier is preferably 0.1 to 10% by weight.

It is preferable that the reaction is performed at 0 atm to 100 atm.

Preferably, the method further includes supplying oxygen during the dehydrogenation reaction. It is preferable to supply oxygen such that the molar ratio of hydrogen for the dehydrogenation reaction is 5 to 20 with respect to the oxygen supplied.

In addition, the reaction may be a slurry reaction using a glass reactor in the form of a continuous stirred tank reactor (CSTR) at normal pressure.

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

In the present invention, carbon tetrachloride was dehydrogenated in an aliphatic alcohol solvent. This reaction is carried out in the presence of a catalyst at a temperature of 298K to 353K to produce chloroform and at least one selected from the group consisting of acetal, aldehyde, alkylvinylether, and dialkylcarbonate.

Chloride ions on the surface of the catalyst can be easily removed by the hydrogen source provided from the aliphatic alcohol, which is a polar solvent, and thus the catalyst deactivation problem in the prior art can be solved because the activity of the catalyst is maintained for a long time.

In addition, aliphatic alcohols (methanol, ethanol, propanol, butanol, etc.) are excellent in reactivity, produce less by-products, and increase carbon tetrachloride conversion and chloroform selectivity.

When the aliphatic alcohol is ethanol, the conversion rate of carbon tetrachloride and the selectivity of chloroform are very predominant, and together with diethyl carbonate, acetal (1,1-diethoxyethane), acetaldehyde, and ethyl vinyl by the reactivity of ethanol itself The production of ether is observed.

However, the longer the carbon length of the aliphatic alcohol, the more by-products generated by the reaction of the alcohol itself (such as cracking and isomerization). Therefore, methanol, ethanol, propanol and butanol are suitable as solvents among alcohols. Alcohols, except methanol, directly participate in the reaction in the dechlorination of carbon tetrachloride to produce more useful dialkylcarbonates and acetals. When methanol is used as a solvent, dimethyl carbonate (DMC) is not produced, and dimethoxymethane (methylal) is mainly produced.

In the dehydrochlorination of carbon tetrachloride, a catalyst containing a transition metal such as platinum (Pt), palladium (Pd), ruthenium (Ru), or nickel (Ni) as a single component, cobalt (Co), tungsten ( W), vanadium (V), copper (Cu), gold (Au), or molybdenum (Mo), and the like can be used a binary metal catalyst. In particular, the activity of the catalyst containing platinum, palladium, or ruthenium is high. In addition, a second metal such as tin (Sn) or alkali metals (Li, Na, and K) can also be used as a promoter in order to suppress formation of a high boiling point compound by polymerization of carbon tetrachloride itself.

As a carrier capable of supporting or ion-exchanging the catalyst used in this reaction, silica (SiO ₂ ), alumina (Al ₂ O ₃ ), carbon, titania (TiO ₂ ), zeolite, silica Alumina (SiO ₂ -Al ₂ O ₃ ), montmorillonite, MCM or alkaline earth metal oxides (MgO, SrO, CaO, BaO, etc.) may be used. Carbon carriers having a low acidity of carriers are particularly preferred in terms of selectivity to chloroform, but considering the reactivity of alcohols, montmorionite and silica-alumina (SiO ₂ -Al ₂ O ₃ ), which have a slight acid point, are more preferable. Do.

The amount of the metal catalyst of the catalyst supported or ion exchanged on the carrier is preferably 0.1 to 10% by weight, preferably 1 to 5% by weight.

The production method of the catalyst is the same as the production method of a general solid catalyst. First, the solid precursor containing the active ingredient (transition metal) is dissolved in tertiary distilled water at 1:50 to 1: 400, or the solution containing the active ingredient is mixed with tertiary distilled water at a ratio of 1:50 to 1: 400. One aqueous solvent may be supported on a carrier by a wet impregnation method, and then dried at 323K to 423K to prepare a solid catalyst. In addition, the method of grafting rather than simply supporting the transition metal on the carrier can prevent the deactivation of the catalyst by leaching of the active ingredient during the reaction.

Therefore, in one embodiment of the present invention, a catalyst was prepared by grafting a precursor of platinum, palladium, or ruthenium to montmorionite pretreated with a cation, in which case the phenomenon of leaching transition metals during the reaction was remarkable. Decreased.

The prepared catalyst is used immediately after drying at around 373K to reduce the activation of active ingredients and excess water, or undergoes a reduction process under a hydrogen atmosphere of 373K to 1173K.

In the above reaction, the reaction temperature is preferably 298K to 353K. If the reaction temperature is less than 298K, the reaction is not performed well, and at a high temperature of 353K or higher, C2 compound is formed as a by-product, and the selectivity of dialkyl carbonate is reduced by cracking of alcohol, especially hydrochloric acid produced during the reaction. The amount of excess water may increase and the reactor may corrode.

In the reaction, the pressure is preferably maintained at normal pressure to 100 atmospheres. In the case of dehydrochlorination of carbon tetrachloride with an alcohol as a solvent, the conversion rate and product distribution are not significantly affected by the reaction pressure, but the conversion rate of carbon tetrachloride is increased by increasing the reaction pressure. There is a need to select the reaction pressure and the molar ratio of solvent and carbon tetrachloride.

Therefore, the reaction is also preferably made in the slurry phase using a glass reactor in the form of a CSTR at atmospheric pressure. The reaction of carbon tetrachloride and alcohol is very good for all catalysts used in the present invention when the reaction proceeds in a slurry phase in CSTR, as well as to prevent corrosion of the reactor.

In the above reaction, it is preferable to optionally add gaseous oxygen. Adding oxygen in the gas phase can improve the selectivity of the dialkyl carbonate. In particular, when the molar ratio of hydrogen and oxygen (hydrogen / oxygen) is set to 5 to 20, and excess hydrogen is used, generation of by-products can be suppressed. That is, in this reaction, dialkyl carbonate is produced by oxidation of carbon-carbon double bond of ethyl vinyl ether by hydrogen peroxide produced by reaction between hydrogen and oxygen, so the presence of oxygen is important, but the ratio of oxygen is high. If too much hydrogen peroxide is produced, the reverse reaction of the product and the side reaction of carbon tetrachloride become more severe, resulting in lower overall yield of desired products (chloroform, dialkyl carbonate, and acetal, etc.). In addition, when the hydrogen is used in excess, dehydration of alcohol by oxygen occurs less, and the production of hydrochloric acid and water is reduced, thereby preventing corrosion of the reactor and the apparatus.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, these examples are for illustrative purposes only, and the scope of the present invention is not limited to these examples.

Example

Comparative Example 1-3

Dehydrochlorination of carbon tetrachloride was carried out in various solvents. 12 hours reaction using 3.0 wt% Pd / activated carbon 0.1g as catalyst, temperature 323K, pressure (H ₂ ) 435 psig, carbon tetrachloride 64.5 mmol, carbon tetrachloride / solvent weight ratio 1.0, internal standard (n-undecane) 1.3 mmol I was. Dielectric constant / polarity values are described by FC Carey, RJ Sundberg, "Advanced Organic Chemistry; Part A", 3rd edition. (1993) Refer to the data reported on page 233.

The reaction results are shown in Table 1 below.

In the nonpolar solvents 1,4-dioxane, tetrahydrofuran, and acetonitrile, the selectivity of chloroform decreased as the conversion rate of carbon tetrachloride increased with increasing polarity of the solvent. Since there is little, it is considered to be useful as a solvent in the dehydrogenation reaction of carbon tetrachloride in the catalytic reaction considering the separation process. The difference in reactivity according to the type of solvent is shown to be mainly related to the stability of the chloride ions produced during the reaction in the presence of the solvent.

Example 1

The reaction was carried out in the same manner as in Comparative Example 1-3 except that ethanol was used as the solvent.

The reaction results are shown in Table 1 above.

When ethanol was selected and reacted in the polar solvent, the conversion rate of carbon tetrachloride and the selectivity of chloroform were very predominant. In addition, the reactivity of ethanol itself caused diethyl carbonate, acetal (1,1-diethoxyethane), acetaldehyde, And production of ethyl vinyl ether was observed.

In addition, chloride ions on the surface of the catalyst can be easily removed by the hydrogen source provided in the polar solvent, so that the activity of the catalyst can be maintained for a long time.

Example 2-11

Preparation of the catalyst:

A catalyst was prepared by ion exchange of (CH ₃ CN) ₂ PdCl ₂ palladium precursor corresponding to 2.8 wt% in pretreated H-monomolinite and drying at an oven temperature of about 373 K. This catalyst was used directly in dehydrochlorination of liquid carbon tetrachloride in Example 2-11. The method for preparing a monmolionite catalyst substituted with a transition metal is described in J. Mol. Catal. A 144, (1999), page 431, described in detail.

Example 2

0.1 g of 2.8 wt% Pd / Mont catalyst, reaction temperature of 323 K, hydrogen pressure of 435 psig, carbon tetrachloride 64.5 mmol, ethanol 217.4 mmol, internal standard (n-undecane) 1.3 mmol, reaction time 3 hours, 6 hours Changes in conversion and product distribution over 12 hours and 17 hours were investigated.

In order to prevent corrosion of the 300 ml high pressure Parr reactor, the reaction was performed after injecting the reactant into the inserted 50 ml glass reactor.

The reaction results are shown in FIG. 2.

Figure 2 is a graph showing the distribution of the product distribution by the conversion of carbon tetrachloride and ethanol with the reaction time in the reaction conditions in the absence of excess oxygen, no further changes were made in the reaction time more than 12 hours. In other words, the carbon tetrachloride selectivity of chloroform increased from about 90% to about 95% as the reaction time progressed, and the formation of C ₂ H _x Cl _y compounds showed the opposite trend. When ethanol was used as the solvent, 1,1-diethoxyethane (acetal) increased with the decrease of the reaction intermediate, ethyl vinyl ether, and diethyl carbonate was initially caused by a small amount of oxygen present in the reactant. It appears to be generated by the impact and the value remained constant.

Example 3-5

In Examples 3 to 5, the amount of carbon tetrachloride as a reactant was fixed at 64.5 mmol, and the amount of ethanol was changed as shown in Table 2, at a reaction temperature of 323 K and hydrogen pressure of 435 psig, 2.8 wt% Pd / Mont catalyst of 0.1 g, The reaction was carried out using 1.3 mmol of internal standard (n-undecane).

The results of the reaction are shown in Table 2 below. Table 2 shows the effect of the amount of ethanol used as the solvent on the Pd / Mont catalyst on the reaction activity.

Comparative Example 4

The reaction was carried out under the same conditions as in Examples 3 to 5 except that the amount of ethanol was zero.

The reaction results are shown in Table 2 above.

According to the reaction results of Examples 3 to 5 and Comparative Example 4, as the amount of ethanol increased, the conversion rate of carbon tetrachloride and the selectivity of chloroform increased, and the conversion rate of ethanol also increased. In the case of not using ethanol as a solvent, the chloroform selectivity was about 10%, but the production of C2 compound was superior. However, when the molar ratio of ethanol and carbon tetrachloride was about 6.7, the selectivity of chloroform was improved to about 95%. In addition, as the molar ratio of ethanol to carbon tetrachloride increased, the conversion of ethanol also increased, but the selectivity of 1,1-diethoxyethane showed a tendency to decrease, which was decomposed by reverse reaction of 1,1-diethoxyethane during the reaction. This is because ethanol and ethyl vinyl ether are produced.

Example 6-8

The reaction was carried out for 6 hours under the same conditions as in Example 2 except that the hydrogen pressure was changed as described in Table 3 below.

The results of the reaction are shown in Table 3 below.

As shown in Table 3, the liquid dechlorination reaction of carbon tetrachloride showed that the conversion of carbon tetrachloride increased slightly with increasing hydrogen pressure in the presence of ethanol, but was not significantly affected, and the conversion rate of carbon tetrachloride was higher than 653 psig. It did not increase. The conversion of carbon tetrachloride was carried out in the same conditions as in the pressurized reaction for 12 hours except that the reaction gas was continuously flowed while maintaining the pressure at atmospheric pressure in a reactor of the atmospheric stirred tank reactor (CSTR) type. At 50%, the selectivity of chloroform showed similar reaction results of more than 95%. In addition, the selectivity of 1,1-diethoxyethane by the conversion of ethanol also showed a similar result to the pressurization reaction, so that the atmospheric pressure glass reactor is also applicable to this reaction.

Example 9-10

The reaction was carried out under the same conditions as in Example 2 except that the reaction time was 6 hours as shown in Table 4 below.

Results: The results of the reaction are shown in Table 4 below. This is the result of confirming the influence of the reaction temperature.

When the reaction temperature was less than 353K, the conversion rate of carbon tetrachloride was greatly improved from 28% (323K; Example 6) to 63% (353K; Example 10) by the increase of the reaction temperature. At this temperature, however, the formation of C 2 compounds by the oligomerization of carbon tetrachloride increased significantly. The conversion rate of ethanol showed a tendency to decrease with the increase of reaction temperature, which is shown to be due to the reverse reaction of 1,1-diethoxyethane, the main product, so the reaction temperature of this reaction was performed at a low temperature of 298-353K. It was found to be the most desirable.

Example 11-17

In the absence of excess oxygen, the reaction was carried out for 12 hours using a temperature of 323 K, pressure (H ₂ ) 435 psig, carbon tetrachloride 64.5 mmol, ethanol 217.4 mmol, and catalyst 0.1 g, and the catalysts were each as shown in Table 6 below. Catalysts with various properties were used.

After the reaction, the heterogeneous solid catalyst was separated by filtration and the amount of transition metal present in the remaining product was measured by ICP-AES method to evaluate the stability of the catalyst from the leached amount.

The acid amounts, acid strengths, and specific surface areas of alumina (Al ₂ O ₃ ), carbon, silica-alumina (SiO ₂ -Al ₂ O ₃ ), and monmolionite used as carriers are shown in Table 5 below.

The method of preparing the catalyst described in Table 5 was as follows.

2.8 wt.% Pd / Mont (Example 11): Pre-treated H-monomolinite was grafted (CH ₃ CN) ₂ PdCl ₂ as a palladium precursor and dried at 373K.

3.0 wt% Pd / Activated Carbon (Example 12): PdCl ₂ was prepared by wet impregnation of activated carbon as a palladium precursor and dried at 373K.

5.0 wt.% Pd / Al ₂ O ₃ (Example 13): PdCl ₂ was prepared by impregnation of Al ₂ O ₃ as a palladium precursor and dried at 373K.

3.0 wt% Pd / SiO ₂ -Al ₂ O ₃ (Example 14): PdCl ₂ was prepared by impregnating SiO ₂ -Al ₂ O ₃ as a palladium precursor and dried at 373K.

2.5 wt% Pt / Mont (Example 15): Pre-treated H-monomolinite was grafted (CH ₃ CN) ₂ PtCl ₂ as a platinum precursor and dried at 373K.

3.0 wt% Pt / Activated Carbon (Example 16): H ₂ PtCl ₆ as a platinum precursor was prepared by impregnating activated carbon and dried at 373K.

1.0 wt.% Pt / Al ₂ O ₃ (Example 17): H ₂ PtCl ₆ was prepared by impregnating Al ₂ O ₃ as a platinum precursor and dried at 373K.

After the reaction was performed for 12 hours in an atmosphere where oxygen was not optionally added using the catalyst, it was analyzed using HP-GC and HP-GC MSD (mass selective detector).

The results of the reaction are shown in Table 6 below. The main products of C ₂ H _x Cl _4-x ^a are C ₂ Cl ₄ and C ₂ HCl ₃ (x = 0 to 2). The leaching amount ^b is a value with respect to the total metal amount of 0.1 g of a raw catalyst.

As shown in the case of Examples 12 and 16, the selectivity of chloroform on the platinum or palladium catalyst supported on activated carbon was the highest, especially on the catalyst supported on palladium. However, on the platinum or palladium catalyst supported on activated carbon, the conversion rate of ethanol was relatively low and the distribution ratio of products (1,1-diethoxyethane, acetaldehyde, ethyl vinyl ether, diethyl carbonate, etc.) by the reaction of ethanol was similar. Was observed. However, platinum or palladium catalysts (Examples 11 and 15) ion-exchanged with montmorionite have high conversion rates of carbon tetrachloride and ethanol, and select 1,1-diethoxyethane as a useful catalyst. It is possible. However, the selectivity of chloroform tended to decrease slightly compared to the catalyst supported on activated carbon. In the catalysts supported on the alumina of Examples 13 and 17, the selectivity of chloroform was decreased, and a significant portion of ethanol was converted to acetaldehyde. As shown in Table 5, the selectivity of chloroform was slightly decreased on the palladium catalyst supported on SiO ₂ -Al ₂ O ₃ having a relatively high acidity on the surface, but the conversion of ethanol was compared with that of the monmolionite catalyst. Even higher.

When the dehydrogenation reaction of carbon tetrachloride was carried out in the presence of an alcohol solvent such as ethanol, all the catalysts containing platinum or palladium used in this example had higher selectivity of chloroform than in the case of not using alcohol as a solvent. And alcohols produced useful products. For Comparative Example 4, where no alcohol was used as the solvent, carbon tetrachloride was mainly converted to C ₂ compounds and the selectivity to chloroform was less than 11%. However, in Examples 15 and 16, 7.5% or 32.5% of the supported platinum was lost during the reaction based on the total transition metal content in the catalyst, which is a problem in maintaining and reusing the catalyst. Can be. Therefore, when the dehydrochlorination reaction of the carbon tetrachloride is carried out in the presence of alcohol, the Pd / Mont or Pd / activated carbon catalyst is used for the selectivity of chloroform by the conversion of carbon tetrachloride and 1,1-diethoxyethane by the conversion of ethanol. It is most preferable in terms of production, and since the leaching amount of the transition metal is less than 1.0% even after the reaction, it may be selected as a preferable catalyst of the present reaction.

Example 18-21

Using the catalyst described in Table 7 below, the reaction was carried out under the same conditions as in Example 1 except that the pressure (H ₂ ) 217.5 psig, the pressure (O ₂ ) 14.5 psig.

The reaction results are shown in Table 7 below.

Table 7 shows the product distribution change by the effect of the oxygen addition. In the case of Examples 18-21, in which a small amount of oxygen was added during the reaction to maintain a molar ratio of hydrogen and oxygen at about 15, the production of diethyl carbonate was significantly increased in all catalysts used. In addition, the addition of a small amount of oxygen did not significantly affect the conversion rate of carbon tetrachloride and the selectivity of chloroform, and in this case, carbon tetrachloride and ethanol had the highest reactivity with Pd / Mont catalyst.

Example 22-26

Examples 22 and 23 use the catalysts described in Table 7 below and maintain the pressure of hydrogen and oxygen at 435 psig (H ₂ ) and pressure (O ₂ ) 145 psig, except that the molar ratio of hydrogen and oxygen is maintained at about 3. And the reaction was carried out under the same conditions as in Example 1.

Examples 24 and 25 were carried out under the same conditions as in Example 1 except that the ratio of water and ethanol (water / ethanol) was 0.2 and 1.0, respectively.

Example 26 was carried out under the same conditions as in Example 1 except that the reaction was performed by adding 110 mmol of 30 wt% hydrogen peroxide solution.

The reaction results are shown in Table 7 above. The main products of C ₂ H _x Cl _4-x ^a are C ₂ Cl ₄ and C ₂ HCl ₃ (x = 0 to 2).

According to Table 7, the selectivity of diethyl carbonate was increased to about 50% by increasing the addition amount of oxygen to maintain the molar ratio of hydrogen and oxygen to about 3, but the selectivity of chloroform by the conversion of carbon tetrachloride was It was shown that the selectivity of C2 compound was increased while decreasing below 80%.

Therefore, in view of both the selectivity of chloroform and the selectivity of diethyl carbonate in the present invention, it is preferable to maintain the molar ratio of hydrogen and oxygen at about 5 to 20 as a condition that can obtain the desired product in the highest yield.

The production of such diethyl carbonate is carbonyl group by oxidation of carbon-carbon double bond of ethyl vinyl ether precursor which is a reaction intermediate by hydrogen peroxide produced in-situ by reaction of hydrogen and oxygen as shown in Example 26. It is thought to be due to the formation of.

In addition, when comparing the results of Examples 24 and 25, in the dehydrogenation of carbon tetrachloride, the water produced by the dehydration of alcohol acts as a negative factor to reduce the selectivity of chloroform, so it is necessary to consider a method for removing the same. There is this.

As described above, according to the dehydrogenation reaction for treating carbon tetrachloride of the present invention, when ethanol, which is a kind of aliphatic alcohol, is used as a solvent, a useful product such as dialkyl carbonate may be produced by a process without using phosgene. Can be. Existing processes for the production of dialkyl carbonates have all been performed using phosgene or oxidative carbonylation of carbon monoxide and alcohols, and therefore the risk of explosion, low dialkyl carbonate yield and toxic phosgene should be used. There was a disadvantage in the process. However, the reactions presented in the present invention can produce dialkyl carbonates in high yields in dehydrochlorination reactions with relatively low risk. In particular, a method of artificially adding a small amount of oxygen in the reaction as a method for improving the production of diethyl carbonate rather than 1,1-diethoxyethane by the reaction of ethanol which is a kind of alcohol in the present reaction.

As described above, according to the present invention, even in the low temperature region (289-353K), it shows high conversion rate of carbon tetrachloride and selectivity of chloroform, can produce useful by-products such as dialkyl carbonate and acetal, and lower catalyst deactivation. Carbon tetrachloride can be treated efficiently and usefully.

In addition, the present invention is very useful because it can reduce the risk of explosion and produce useful products such as dialkyl carbonates without the use of low dialkyl carbonate yields and toxic phosgene.

Claims (9)

Mixing carbon tetrachloride with an aliphatic alcohol to obtain a carbon tetrachloride-alcohol mixed solution; Dehydrochlorination of the carbon tetrachloride-alcohol mixed solution in the presence of a catalyst at a temperature of 298K to 353K to produce at least one selected from the group consisting of acetal, aldehyde, alkylvinyl ether and dialkyl carbonate and chloroform. Treatment method. The method of claim 1 wherein the aliphatic alcohol is a C ₁ to C ₄ aliphatic alcohol. The method of claim 1 wherein the catalyst is at least one metal selected from the group consisting of platinum, palladium, and ruthenium. The catalyst of claim 3, wherein the catalyst is supported on at least one carrier selected from the group consisting of montmorillonite, activated carbon, MCM, SiO ₂ , Al ₂ O ₃ , SiO ₂ -Al ₂ O ₃ , or zeolite. Or ion exchanged. The method of claim 4, wherein the amount of metal catalyst of the catalyst supported or ion exchanged is 0.1 to 10% by weight. The method of claim 1 or 2, wherein the reaction is carried out at 0 atm to 100 atm. The method according to claim 1 or 2, further comprising the step of supplying oxygen during the dehydrogenation reaction. 8. The method of claim 7, wherein the oxygen is supplied such that the molar ratio of hydrogen for the dechlorination reaction is 5 to 20 with respect to the oxygen supplied. The method of claim 1, wherein the reaction is carried out in a slurry phase using a reactor in the form of a CSTR at atmospheric pressure.