JPH0419978B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing ethylene glycol from methanol. Emphasis is being placed on the use of syngas as a starting material for various chemicals such as methanol, formaldehyde, and ethylene glycol, in place of oil, whose production is declining and oil is rising in price. The advantage of syngas is that it can be produced from raw materials other than petroleum, such as natural gas or coal and possibly oil shale and tar sand. An example of an industrial method for producing ethylene glycol using synthesis gas as a starting material is to react formaldehyde with carbon monoxide and water at high pressure (more than 300 atmospheres) in the presence of an acid catalyst, convert it into hydroxyacetic acid (glycolic acid), and then combine it with methanol. This method involves reacting to form a methyl ester, which is then converted into a glycol by catalytic hydrogenation. Kotskaril's U.S. patent issued on April 13, 1943.
No. 2316564, issued April 4, 1939 to Larson, U.S. Pat. See US Pat. No. 2,331,094, published May 5, 2003. Another method of using synthesis gas for ethylene glycol production is the reaction of methanol and carbon monoxide using a rhodium catalyzed high pressure process. U.S. Pat. No. 4,115,428 to Vaidar et al. and 1978 No. 9 to Kosbey et al.
See U.S. Pat. What is important about the method of manufacturing ethylene glycol announced here is that oxidative dimerization or dehydration dimerization of various organic compounds using hydrogen peroxide is a very simple process developed by free radical theorist MS Karlasch and his students. It is an old method. This work became the basis for Zuzu and later free radical chemistry. In JACS 16, 15, 1943, Carlatsch et al. reported that the dehydration dimerization of acetic acid to succinic acid using acetyl peroxide had a utilization selectivity of 50 mol% based on acetyl peroxide (utilization selectivity =
It has been reported that the number of moles of dehydrated dimer produced/number of moles of peroxide changed) can be achieved. isobenzoic acid is
Tetramethylsuccinic acid was produced with a utilization selectivity of 42.4 mol%. Karlatsiyu et al. J.Org.Chem. 10,
386, 1945, reported that the ester methyl chloroacetate could be dimerized to dimethyl chlorosuccinate with acetyl peroxide with a utilization selectivity of 41%. Karlatsiyu et al. J.Org.Chem.
10, 401, 1945, cumene and ethylbenzene were dimerized with acetyl peroxide to form their dehydrated dimers at 61.9 mol% and 32.1 mol%, respectively. Wiles et al. IE ₄ C. August 1949, page 1682, report the efficiency of 2,2 bis(t-butylperoxy)butane to di-t-butyl peroxide for cumene dimerization. Dimerization of the benzoate ester of benzyl alcohol with di-t-butyl peroxide to the corresponding glycol, diphenylene glycol, to the dibenzoate ester is reported in Last et al., JACS 70, 3258 (1948). There are many examples in the literature of producing very low concentrations of dehydrated dimer with utilization selectivity of typically 20-50 mole percent based on consumed peroxide. These selectivities are generally too low for a method to be considered for industrial development. Two reports of peroxide-using reactions with respect to ethylene glycol need to be mentioned. The first is Angew by Szwetztryk et al.
Chemc, 72, 1960, No. 21, pages 779-780, in a molar ratio of 1:20, is heated at 140° C. for 10 hours in an autoclave or under reflux. It's a method. An ethylene glycol yield of 26% was reported, and it is said that the yield increases with an increase in excess alcohol. Another reaction method to ethylene glycol that is more important in relation to the second invention is described by Oyama, J.
Org.Chem, 30, 2429-2432, July 1965. In particular, Oyama has 9 moles of methanol.
1.8 mol of 15% formaldehyde aqueous solution and t-
Butyl peroxide (di-tert-butyl peroxide) was reacted at 140°C for 12 hours to produce 0.21 mol of ethylene glycol (upper right column of the table on page 2430), and the following is written directly below the table: ``Formaldehyde and The yield of ethylene glycol in the methanol reaction is higher than that in the dimerization reaction of methanol with t-butyl peroxide.This fact indicates that the hydroxymethyl group (D)
is added to formaldehyde. ” Oyama describes in detail the products obtained by carrying out this reaction and describes it in “Experiments” on page 2431.
(particularly, the title of this part is "Reaction of methanol and formaldehyde" and "Dimerization of methanol" is on page 2432). Dehydration of methanol when t-butyl peroxide is present and formaldehyde is not present. It is compared with embodiment. The yield of ethylene glycol obtained by Oyama is quite low. Oyama's only test of using methanol (the above reaction of methanol, aqueous formaldehyde and t-butyl peroxide at 140°C for 12 hours) produced only 1.86% by weight of ethylene glycol. The above reaction can produce ethylene glycol in a higher yield by substantially reducing the amount of organic peroxide used compared to the amount of formaldehyde and methanol used in Oyama. Furthermore, the increase in the amount of methanol and decrease in the amount of water compared to the other components in the reaction mixture compared to the amount of Oyama used also appears to contribute to the production of higher yields of ethylene glycol. Therefore, for example, if a mixture of 78.5% by weight methanol, 1.5% by weight di-tert-butyl peroxide, 6.9% by weight formaldehyde and 13.1% by weight water is heated at 155°C for 2 hours, a yield of 4.5% by weight will be produced in the reaction mixture. Ethylene glycol is obtained.
This corresponds to a yield of about 7.1 moles of ethylene glycol per mole of di-tert-butyl peroxide used. (Oyama uses ethylene glycol per mole of di-tert-butyl peroxide in the reaction.
0.466 mol). This improved method is detailed in US patent application Ser. No. 183,537, filed September 2, 1980. According to the invention, improved yields of ethylene glycol are obtained by the reaction of methanol with formaldehyde and peroxide added in portions to a methanol-containing liquid medium. During the reaction, portions of formaldehyde and peroxide are added to the liquid reaction medium to allow at least a portion of the final conversion reaction of the reactants formaldehyde, peroxide and methanol to take place before the next additional portion of formaldehyde and peroxide is added. The next addition portion of formaldehyde and peroxide is added to the methanol reaction zone where the final conversion reaction of the reactants takes place and the glycol concentration in the reaction medium to which the subsequent portion is added is the same as that of the previous portion. becomes larger than Additions of formaldehyde and peroxide are added until all of the reactants used in the process are added to the reaction zone and reaction conditions are reached. In the process of the invention, if the formaldehyde and peroxide reactants are added in small portions to the methanol, compared to the amount of ethylene glycol produced in the process if the total amount of reactants used in the process is initially in the reaction medium, Large amounts of ethylene glycol are produced. Formaldehyde, peroxide and methanol may be reacted in the presence of a small amount of a basic substance which serves to reduce the hydrogen ions produced in acid form during the reaction without disturbing the ethylene glycol content. During the reaction, these acids come into contact with the formation of unnecessary by-products such as methylal, so basic substances have the effect of significantly reducing the amount of by-products formed by neutralizing all or part of the acids. . In the present invention, the basic substance may be present in the liquid reaction medium from the beginning of the reaction or may be added to the reaction medium in portions together with formaldehyde and peroxide. The amount of basic substance used must be sufficient to neutralize or partially neutralize the acid produced so as to prevent the acid-catalyzed reaction of methanol and formaldehyde to methylal. When excess basic material is added to the reactants, the formaldehyde present can be converted to fuformose sugars, which is easily seen by the amber color of the reactants and is responsible for the characteristic odor of the reaction and the low formaldehyde content of this method. Become. Excess basic substances may also inhibit ethylene glycol production. As used herein, "moiety" refers to a portion of the formaldehyde, peroxide, and in some cases basic material that will be added to the methanol-containing liquid reaction medium during the reaction. For example, the amounts of these reactants can be divided into two portions, with one portion added at the beginning of the reaction and the remainder added later to complete the reaction. This becomes a two-stage addition reaction. “Multi-stage addition” or “addition”
refers to the partial addition of formaldehyde, peroxide, and in some cases basic substances in two or more steps, or even up to ten steps if necessary, and in some cases the reactants can be added in small amounts at a steady state over the reaction time. "Conversion of small additions of formaldehyde and peroxide" is defined as the reaction of formaldehyde and peroxide with methanol to form other products. As used herein and in the claims, "basic substance" refers to a substance that is alkaline and controls the amount of hydrogen ions produced in acid form during the reaction. Suitable basic substances include the hydroxides of alkali metals such as lithium, sodium, potassium, rubidium or cesium or alkaline earth metals such as calcium, strontium, barium or magnesium. Basic substances include alkali or alkaline earth metals and weakly ionized acids such as oxalic acid, tartaric acid, malic acid, citric acid, formic acid, lactic acid, acetic acid, carbonic acid, phosphoric acid, and pyrophosphoric acid. , pyrophosphorous acid, propionic acid, benzoic acid and salts of the acids known in the art. Of particular interest for purposes of the present invention are the sodium or potassium salts of weakly ionized acids such as acetic acid, formic acid, oxalic acid, carbonic acid (including bicarbonate) or phosphoric acid. Examples of these sodium and potassium salts include sodium acetate, potassium acetate, sodium bicarbonate, potassium bicarbonate, sodium formate, potassium formate, sodium oxalate, potassium oxalate, sodium carbonate, potassium carbonate, sodium pyrophosphate, pyrophosphate. Potassium acid, sodium phosphate, potassium phosphate, sodium diphosphate, potassium diphosphate, etc. The amount of sodium or potassium salt of a weakly ionized acid added to the reactants ranges from about 50 to about
3500 ppm, preferably about 100 to about 3000 ppm, most preferably about 100 to about 1500 ppm. In the case of other basic substances, the amount should be equivalent to the amount prescribed for the sodium or potassium salts of weakly ionizing acids for their ability to neutralize hydrogen ions in the system. If a metal hydroxide such as sodium hydroxide or potassium hydroxide is used as the basic substance, the amount added must be greater than the amount that would be required to neutralize the acid produced during the reaction. For example, if sodium hydroxide is used as the basic substance, the amount of gold reaction product will be about 25 to about 60 ppm.
This method reduces the amount of methylal without significantly sacrificing the amount of ethylene glycol produced compared to a reaction that does not involve a basic substance. Basic substances that can be used in addition to the foregoing include zinc oxide, basic alumina, various basic sodium compounds, and generally reduce the hydrogen ions of the produced acids without significantly reducing the by-product ethylene glycol production. There are various basic substances. Generally, the reaction mixture used in this invention is about 0.25
% to about 25% by weight, preferably not more than about 6% by weight, and most preferably from about 0.75 to 3% by weight of organic peroxide. In most cases the reaction mixture will also contain about 45 to about 97% by weight, preferably about 80 to about
It contains 85% by weight methanol, about 0.5 to about 13% by weight, preferably about 2 to about 12% by weight formaldehyde, and about 0.5 to about 35% by weight, preferably about 2 to about 10% by weight water. Generally the reaction is carried out at about 100 to about 200°C, preferably about
It is carried out at a temperature of 125 to about 175°C. In the entire reaction of formaldehyde, peroxide, and methanol to ethylene glycol, it is not necessary that the added reactants be completely converted before adding the next portion of reactants formaldehyde and peroxide. However, at each stage, it is necessary to add a reactant portion and allow it to react for a sufficient time for substantial conversion before adding the next portion or, in the case of the final stage, before removing and purifying the product stream. Generally, the reaction is allowed to proceed for about 5 minutes to about 15 hours, preferably about 30 minutes to about 6 hours. The reaction time for each stage is generally equal to the total reaction time divided by the number of stages. Therefore, the reaction time range for each stage is the total reaction time range divided by the number of stages.
Generally, the higher the temperature, the shorter the reaction time required to bring the reaction to the desired completion state. The pressure at which the reaction is run is of little or no importance and pressures between the autogenous pressure (in a closed reactor) and 600 psig can be used. The organic peroxide used in the reaction of the invention has the formula: R-O-O-R ¹ , where R and R ¹ are alkyl or aralkyl groups each having from 3 to 12 carbon atoms. Organic peroxides that can be used are, for example, di-tert-butyl peroxide, di-cumyl peroxide, tert-butyl-cumyl peroxide and tert-butylethylbenzyl peroxide. Preferred organic peroxides are di-tertiary
Butyl peroxide. Although inert solvents can be used in this method, in most cases it is preferable not to use them. Solvents that do not react under these operating conditions can be used, such as benzene and tertiary butyl alcohol. Generally, if a solvent is used, it will be in an amount up to about 25% by weight of the total reaction medium, although in some cases higher amounts can be used. The reaction can be carried out in batches, placing the initial reaction mixture in a reactor such as a stirred autoclave and adding portions of formaldehyde and peroxide and, if any, basic material in successive portions to the methanol reaction medium. After all of the reactants have been added, the reaction is continued until the desired degree of reactivity is reached and the product mixture is removed and purified. Other methods are quasi-continuous in which the initial reaction mixture and additional reactants are charged in a methanol reaction medium, and the reaction takes place;
The product mixture is periodically withdrawn from the reactor and purified. The continuous reaction can be carried out in a reactor configured to provide a glycol concentration gradient under reaction conditions from the point of addition of the first portion of peroxide and formaldehyde to the point of withdrawal of the glycol-containing product. According to the invention, second and subsequent portions of peroxide and formaldehyde are added between the two points. For example, a continuous method involves pouring a liquid reaction medium into a pipe and adding formaldehyde and peroxide reactant portions at intervals along the pipe, creating a moving reaction medium with a glycol concentration gradient as the reaction medium passes through the pipe. Can be implemented. Thus, each additional portion of reactant is added in a controlled manner along the pipe into the reaction medium until all portions have been added. At the end of the pipe or reactor,
The reaction of the reactant parts in the reaction medium results in a product stream containing the desired amount of ethylene glycol after conversion. A diaphragm reactor containing a liquid reaction medium with a glycol concentration gradient between the inlet of the initial feed stream and the outlet of the product stream can also be used. In this case additional portions of peroxide and formaldehyde are added between the ports. In each case the product mixture is purified by conventional methods such as distillation or solvent extraction to the desired purity, preferably fiber grade ethylene glycol and by-products such as tertiary butyl alcohol, methylal, methylformate, glycerin and acetone. It can be grown. The following examples illustrate the invention. Examples 1-6 These examples illustrate formaldehyde (CH ₂ O) in water (H ₂ O), di-tert-butyl peroxide (DtBP) and methanol (MeOH) in the presence of sodium bicarbonate (NaHCO ₃ ).
Figure 2 shows a direct comparison of total reactant equivalent usage using single-stage and multi-stage reactions for the production of ethylene glycol by the reaction. The formaldehyde used in this example is per 1% by weight of formaldehyde used.
Contained 4.54ppm sodium hydroxide. The reactor was a 316 stainless mesh 1 inch diameter pipe with a volume of approximately 85 ml liquid. In the first-stage reaction, all reaction components were placed in a reactor, sealed, and heated at 155° C. and autogenous pressure for 1 hour. In the multi-stage reaction, a reactor containing all methanol was first charged with the reactants di-tert-butyl peroxide, formaldehyde, water and a portion of sodium bicarbonate and heated at 155 DEG C. for 1 hour. After reacting for 1 hour, an additional portion of reactants was added and reacted for an additional hour. After 2 hours, the remaining reactants were added to the reactor and reacted for a final hour. After the completion of the reaction in one stage or each multistage reaction, the reactor is rapidly cooled, evacuated and taken out, and the contents of ethylene glycol (EG) are removed.
and other products were analyzed by gas chromatography. The results of these Examples are shown in the table. The table shows peroxide added to a methanol-containing reactor,
The total amounts of formaldehyde and water at various stages are shown. Amounts of reactants used were reported as weight percent of total materials in the reactor up to that stage. Ethylene glycol was reported as weight percent of the total product mixture. [Table] In each comparative example, that is, Examples 1, 2, and 3.
The same amount of reactants was used for and 4 and 5 and 6. The one-stage reactions used in Examples 1, 3, and 5 produced less ethylene glycol than the corresponding multi-stage reactions of Examples 2, 4, and 6. The increase in the amount of ethylene glycol produced by the first-stage reaction increases the reaction by one step.
Even if the reaction was carried out for more than 3 hours, as in the multi-stage reaction, no results could be obtained. Example 7-21 Methanol (MeOH), di-tertiary butyl peroxide (DtBP), formaldehyde as a mixture of 55% by weight formaldehyde, 35% by weight methanol and 10% by weight water in a 304 stainless steel Hawk cylinder reactor. Charges of various feed compositions consisting of CH ₂ O) and basic materials were added. The total amount of water in the reaction product did not exceed 5% by weight of the total reaction product. The reaction temperature was kept at 155°C. The second portion of each reactant in these examples, in which the reactants were added in two stages to the methanol, was added 1 hour after the initial charge. In the examples in which the reactants were added in three stages, the first two stages were performed in the manner described above, with the third portion of each reactant being added one hour after the addition of the second portion of the reactants. One hour after the final reactant was added, the reaction appeared to be complete, so the reactor was rapidly cooled, evacuated, and removed, and the contents were analyzed for ethylene glycol and other products by gas chromatography. The results of these examples are shown in the table. The table lists the total amounts of peroxide, formaldehyde and basic material charged to the methanol-containing reactor in the first, second and third stages. The basic substances used were sodium bicarbonate (NaHCO ₃ ), sodium formate (NaFO) and sodium acetone (NaOAc). Amounts of reactants used were reported as weight percent of all materials up to that stage in the reactor. The amount of ethylene glycol was reported as weight percent of the total product mixture. [Table] In Examples 7 and 8, di-tert-butyl peroxide was not added in portions to methanol. All peroxide was added at the beginning of the reaction, but formaldehyde was added in portions throughout the reaction in the presence of sodium bicarbonate to yield 8.3-8.4% by weight of ethylene glycol. From Example 9 where formaldehyde and peroxide were added in portions throughout the reaction.
In Example 15, a larger amount of ethylene glycol was obtained than in Examples 7 and 8. The remaining Examples 16 to 21 differ from Examples 9 to 15 in that sodium acetate and sodium formate were used as basic substances instead of sodium bicarbonate. The ethylene glycol production of Examples 16-21 was generally comparable to that of Examples 9-15. Example 22-42 Formaldehyde (MeOH), di-tertiary butyl peroxide (DtBP), as a mixture of 55% by weight formaldehyde, 35% by weight methanol, and 10% by weight water in a 304 stainless steel Hawk cylinder reactor. Various feed compositions consisting of CH ₂ O) and basic materials were charged. The total amount of water in the reaction product did not exceed 5% by weight of the total reaction product. The reaction temperature was maintained at 155°C. 2 reactants
In the examples where the methanol was added in stages, a second portion of each reactant was added to the reactor one hour after the initial charge addition. In the examples in which the reactants were added in three stages, the first two stages were carried out as described above and the third portion of each reactant was added one hour after the addition of the second portion of the reactants. Final partial addition of reactants 1
After some time, the reaction appeared to be complete, so the reactor was rapidly cooled, evacuated, and the contents analyzed for ethylene glycol and other products by gas chromatography. The results of these examples are shown in the table. The table shows the amounts of peroxide, formaldehyde and basic material charged to the methanol-containing reactor in the first, second and third stages. The basic substances used were sodium bicarbonate (NaHCO ₃ ), sodium formate (NaFO) and sodium acetate (NaOAc). The amount of reactants used is the weight percent of all materials up to that stage in the reactor.
It was reported in Ethylene glycol was reported as weight percent of the total product mixture. [Table] [Table] In Examples 22 and 23, di-tert-butyl peroxide was not added in portions to methanol. Furthermore, in Example 23, the basic substance sodium bicarbonate was not added in portions. In these examples, peroxide was added at the beginning of the reaction, but formaldehyde was added in portions over the reaction time. In Examples 24 and 32, in which peroxide and formaldehyde were added in portions, a larger amount of ethylene glycol was obtained than in Examples 22 and 23, in which peroxide was not added in portions. Example 26 shows a six step addition of reactants peroxide, formaldehyde and sodium bicarbonate. Examples 27-29, 30-
32, 33-35 and 36-38 each represent a series of results for each step of the three-step reaction. Example 39 shows a reaction in which peroxide was added in portions but formaldehyde was not added in portions, and Example 40 shows a reaction in which no portions were added. The glycol yield in the product stream of Example 39, in which no formaldehyde addition was made, was that of Example 41, in which both peroxide and formaldehyde were added in two stages.
It was also 8.2%. However, Example 39 uses a larger amount of total peroxide and also
No. 41 used a higher amount of total formaldehyde, so a strict comparison of these examples is not possible.

Claims (1)

[Claims] 1 Methanol, formaldehyde and the formula: R-O-O-R ¹ (wherein R and R ¹ are 3 to 3 carbon atoms)
represents an alkyl or aralkyl group having 12),
In a process for producing ethylene glycol in which an organic peroxide with A portion of the peroxide conversion reaction occurs, and the next added portion contains an ethylene glycol concentration higher than that of the reaction medium in which the portion of the conversion reaction took place and the previous portion was added. An improved method comprising: adding the peroxide and formaldehyde to the reaction medium and continuing the sequential additions until the entire amount of peroxide and formaldehyde is added to the reaction medium and reacted to form the desired amount of ethylene glycol. 2. The method according to claim 1, wherein the peroxide is di-tert-butyl peroxide. 3. Claim 2, in which the total amount of the reactants formaldehyde and di-tert-butyl peroxide is added to the methanol-containing reaction medium in 2 to 10 stages.
The method described in section. 4. Add peroxide to the reaction mixture from about 0.25 to about
4. The method of claim 3, wherein formaldehyde is used in an amount of 25% by weight and formaldehyde is used in an amount of about 0.5 to about 13% by weight of the reaction medium. 5. Claim 2, in which at least half of the formaldehyde and di-tert-butyl peroxide to be reacted are initially reacted in a methanol reaction medium and the remaining part of the formaldehyde and di-tert-butyl peroxide is added later. Method described. 6. Claim 1, wherein the basic substance is present in the reaction medium in an amount sufficient to reduce the hydrogen ions produced during the reaction without significantly reducing ethylene glycol production by by-product formation. Method described. 7. Adding a basic substance to the reaction medium in an amount sufficient to reduce the hydrogen ions produced in the reaction without significantly reducing ethylene glycol production by by-product formation. Method. 8. Addition of a basic substance to the reaction medium in an amount sufficient to reduce hydrogen ions produced in the reaction without significantly reducing ethylene glycol production through by-product formation. the method of. 9. According to claim 4, a basic substance is added to the reaction medium in an amount sufficient to reduce hydrogen ions produced in the reaction without significantly reducing ethylene glycol production by by-product formation. the method of. 10. The method of claim 8, wherein the basic substance is selected from the group consisting of alkaline earth metal and alkali metal hydroxides and salts of the metal hydroxides and weakly ionized acids. 11. The salt according to claim 9, wherein the basic substance is selected from the group consisting of hydroxides of alkaline earth metals and alkali metals, and salts of the metal hydroxides and weakly ionized acids. 12. The method of claim 8, wherein the basic substance is selected from the group consisting of sodium and potassium acetates, formates, oxalates, carbonates and phosphates. 13. The method of claim 9, wherein the basic substance is selected from the group consisting of sodium and potassium acetates, formates, oxalates, carbonates and phosphates. 14 Basic substances include sodium acetate, potassium acetate, sodium bicarbonate, potassium bicarbonate, sodium formate, potassium formate, sodium oxalate, potassium oxalate, sodium phosphate, potassium phosphate, sodium pyrophosphate, and pyrophosphate. selected from the group consisting of potassium and wherein said basic substance is about 50 to about
9. A method according to claim 8, wherein the amount is in the range of 3500 ppm. 15 Basic substances include sodium acetate, potassium acetate, sodium bicarbonate, potassium bicarbonate, sodium formate, potassium formate, sodium oxalate, potassium oxalate, sodium phosphate, potassium phosphate,
selected from the group consisting of sodium pyrophosphate and potassium pyrophosphate, and wherein the basic substance is about 50 to about
10. A method as claimed in claim 9, wherein the amount is in the range of 3500 ppm. 16 The amount of basic substance is approximately based on the total reaction medium.
15. The method of claim 14, wherein the amount is from 100 to about 3000 ppm. 17 The amount of basic substance is approximately based on the total reaction medium.
16. The method of claim 15, wherein the amount is from 100 to about 3000 ppm.