JPS6217574B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing ethylene glycol monotertiary alkyl ether (hereinafter sometimes abbreviated as MAE) from ethylene glycol and tertiary olefin.

Ethylene glycol monoalkyl ethers are generally very useful compounds as solvents,
For example, n-butyl cellosolve (ethylene glycol mono-normal butyl ether), methyl cellosolve, ethyl cellosolve, etc. are currently produced and used on a large scale industrially. Ethylene glycol monotertiary alkyl ethers, especially ethylene glycol monotertiary butyl ether, are a family of these substances and have excellent properties when used as solvents, dispersants, diluents, etc. in industrial fields such as paints and inks. It is a useful substance with

It is known that this MAE can be synthesized from tertiary olefin or a hydrocarbon fraction containing tertiary olefin and ethylene glycol in the presence of an acid catalyst. In addition, strong acid type cation exchange resins are effective as catalysts in this case, for example, in US Pat.
It is known from No. 3317483, No. 3170000, No. 2480940, etc. When producing MAE using these methods, it is important to suppress by-products such as olefin by-product oligomers and ethylene glycol ditertiary alkyl ethers to increase the selectivity of MAE, and to maintain production conditions for high yields of MAE. The choice is a critical issue that determines the economics of the process. However, the conditions for achieving high MAE selectivity and the raw material ethylene glycol are
Since there is a conflict between the conditions for reacting at a conversion rate close to 100% and the conditions for maximizing the space-time yield of product MAE, the conversion rate per pass of the supplied ethylene glycol is increased to close to 100% to convert ethylene glycol. A process that does not recycle is not practical, and as an industrial process, it involves the recycle of unreacted ethylene glycol. Therefore, the reaction mixture, ie, crude MAE, produced by these known reaction methods usually contains, in addition to the target MAE, unreacted tertiary olefin-containing or non-containing hydrocarbons, unreacted ethylene glycol, olefin by-product oligomers, and ethylene. glycol ditertiary alkyl ether,
It contains the reaction solvent used as necessary, and when a tertiary olefin-containing hydrocarbon fraction that also contains n-olefins is used as a raw material, it also contains some by-produced ethylene glycol monosecondary alkyl ether. It can be done. Furthermore, when water is also added to the reaction raw materials for the purpose of co-producing MAE and tertiary alcohol, the reaction mixture also contains the tertiary alcohol and unreacted water in addition to the above substances. In order to obtain high-purity product MAE and tertiary alcohol from such crude MAE, and to recover ethylene glycol for recycling, well-known purification methods such as extraction, distillation, and extractive distillation are generally employed. Ru. For example, first, the reaction mixture is distilled under pressure in the first column to separate a hydrocarbon fraction containing or not containing unreacted tertiary olefin, and then one or several distillation columns are used to remove azeotropic substances such as water. Using the azeotrope used, tertiary alcohol, part of MAE, olefin by-product oligomers, by-product ethylene glycol dialkyl ether, etc. are separated from the top of the column as an azeotropic mixture to obtain a residue mainly consisting of MAE and ethylene glycol. A conceivable step is to separate this residue in a finishing rectification column, and recover the target high-purity MAE from the top of the column and ethylene glycol from the bottom of the column. However, when active ferrous materials such as iron, carbon steel, and other iron-containing alloys are used in the wetted parts of such purification processes (distillation columns, extractive distillation columns, extraction columns, intermediate tanks, piping, etc.), The recovered ethylene glycol obtained as the residue at the bottom of the distillation column contains iron (dissolved and suspended) in amounts ranging from several ppm to several thousand ppm. It has been found that when iron is directly supplied to a reactor packed with a type cation exchange resin catalyst, the iron content lowers the catalyst activity and causes various problems such as clogging of the catalyst packed bed.

For example, Ciel's "Corrosion Data" shows that ethylene glycol slightly corrodes iron containers.
Survey” (1960). However, this problem has only been addressed as a problem of corrosion of equipment handling ethylene glycol and the purity of ethylene glycol products, and that ethylene glycol that has come into contact with iron containers is a strong acid. It has not been reported that problems such as deterioration of catalyst activity occur during reactions using type cation exchange resin catalysts.For example, in the purification process of industrial equipment for producing ethylene glycol, there are no problems other than the final product distillation column. Although mostly made of carbon steel, no particular problems have been encountered during long-term industrial manufacturing.

Most of the iron present in recovered ethylene glycol exists in a suspended or floc state, but it is not clear what kind of compound it is. From the color and appearance, it is possible that different compounds are formed depending on whether or not water coexists in the system. The amount of iron in recovered ethylene glycol varies depending on the time and temperature at which ethylene glycol is in contact with iron, but for example, if ethylene glycol is in contact with an iron container for several tens of hours at approximately 100 to 120 degrees Celsius, approximately 900 ppm of iron may be mixed in. It has been confirmed. Filtration is the first possible method for removing such mixed iron, but even with filtration using a Millipore membrane with a pore size of 0.45 microns, complete removal is difficult;
It was found that ppm to several tens of ppm of iron was still present. In addition, this filtrate was treated with cation exchange resin, activated carbon, etc., but it was extremely difficult to completely remove any of them, and if the recovered ethylene glycol treated with this method was continuously circulated for a long period of time, strong acid type cation exchange resin It became clear that the catalytic activity of It is conceivable to directly remove iron from the recovered ethylene glycol containing iron using a cation exchange resin, but suspended or flocculent iron is not removed quickly and causes clogging of the treatment tower. Therefore, the filtrate that had been filtered as described above was subjected to iron removal treatment using a cation exchange resin under normal deionization treatment conditions (LHSV value of about 2 to 3 hr ^-1 and temperature of about 40°C). Surprisingly, the removal rate of iron is only 1 to 2% of the ion exchange capacity, making treatment with cation exchange resins impractical.

Since the iron produced during the refining process deteriorates the catalyst in the reaction process, it is also possible to construct not only the reactor but also the equipment for the refining process with materials that do not elute iron, such as glass lining, inert materials such as titanium, etc. However, it turned out that this method could not be adopted industrially. This is because if all the equipment for the reaction and purification steps are made of materials that do not contain iron, such as glass, there is a problem that significant decomposition of MAE and tertiary alcohol will occur in the refining process. After various investigations into the cause of the decomposition, it was confirmed that the cause was acidic substances such as organic sulfonic acids eluted from the strongly acidic cation exchange resin used as a catalyst. Decomposition occurs even in the presence of trace amounts of about 6×10 ^-6 mol/. The amount of eluted acidic substances is particularly large at the beginning of continuous reaction, and the concentration in the reaction mixture may exceed approximately 0.01 chemical equivalent/equivalent, and the eluted acid concentration decreases to approximately 10 ^-4 after several days have passed from the start of the reaction. It becomes ~10 ^-5 chemical equivalent/, and although it gradually decreases thereafter, it continues to elute even after a considerable period of time, for example, half a year. A known method for removing such eluted acids is a neutralization method by adding a strong basic substance such as sodium hydroxide, calcium oxide, or calcium hydroxide. However, this method requires an additional basic substance,
It is difficult to control the amount added in response to fluctuations in the concentration of the eluted acid, and removal of the generated salts also poses a new problem.

As a result of various studies to solve these problems, the inventors of the present invention found that recovered ethylene glycol containing iron obtained in the refining process can be completely removed by simply vaporizing the ethylene glycol through a simple process such as simple distillation. The present invention was completed based on the discovery that ethylene glycol from which the iron content has been removed does not reduce the catalytic activity even if it is recycled to the reaction process. Furthermore, the decomposition of MAE and tertiary alcohol during the refining process due to acidic substances eluted from the strong acid type cation exchange resin catalyst can be significantly prevented by constructing the refining process equipment with iron materials, and recovery is possible. The present invention was completed by discovering that iron contained in ethylene glycol has an extremely effective decomposition inhibiting effect.

That is, the gist of the first invention of the present invention is to cause ethylene glycol and tertiary olefin to react by passing the ethylene glycol and tertiary olefin through a fixed bed filled with a strong acid type cation exchange resin catalyst, When the mixture is purified in a purification process including a distillation means to obtain a highly pure ethylene glycol monotertiary alkyl ether, at least a part of the equipment in the purification process is made of iron material, and the distillation column bottom residue is removed in the purification process. Before recycling the ethylene glycol recovered as part of the reaction raw material, the ethylene glycol contained in the bottom residue of the distillation column is vaporized to remove iron-based impurities, and then a part of the reaction raw material is used. A method for producing ethylene glycol monotertiary alkyl ether, characterized in that the ethylene glycol monotertiary alkyl ether is recycled. The gist of the second invention of the present invention is that, in addition to the method of the first invention, a residue containing iron remaining after vaporizing ethylene glycol from the bottom residue of the distillation column or an impurity consisting of iron obtained in the purification process is provided. At least a portion of the fraction containing ethylene glycol monotertiary alkyl ether is mixed with the reaction mixture exiting the reactor or the crude ethylene glycol monotertiary alkyl ether for purification.
A method for producing an ethylene glycol monotertiary alkyl ether, characterized by obtaining an alkyl ether.

The reaction step itself of reacting ethylene glycol and tertiary olefin can be carried out according to a known method. Tertiary olefins (olefins having a double bond at the tertiary carbon) include isobutylene, isoamylene, having 4 or more carbon atoms, especially 4 to 6 carbon atoms;
Isohexylene (e.g. 2-methyl-pentene-
2 etc.) are preferred, and a fraction containing a tertiary olefin may also be used. _C4 fraction, _C5 fraction obtained from hydrocarbon cracking equipment such as naphtha and kerosene fraction,
The C ₆ fraction contains tertiary olefins and is preferred. Examples of strong acid type cation exchange resins used as catalysts include styrene sulfonic acid type cation exchange resins, phenolsulfonic acid type cation exchange resins, sulfonated coal, sulfonated asphalt, etc. There are things that indicate gender. Furthermore, the physical structure of these cation exchange resins can be either a gel type or a giant network structure. The catalyst has an average particle size of 0.1~
A diameter of 10 mm is preferable. The reaction between ethylene glycol and tertiary olefin may be carried out in the presence of water in the reaction system; in this case, ethylene glycol monotertiary alkyl ether and tertiary olefin may be reacted together.
It is co-produced with grade alcohol. A reaction solvent may be used if necessary. The reaction can be carried out by flowing ethylene glycol, water and tertiary olefin in cocurrent or countercurrent through a fixed bed packed with a catalyst from the upper or lower end. The size of the fixed bed is not particularly limited. The packing height of the catalyst is usually 0.2 to 20 m. Several fixed beds can also be used in series or in parallel. The liquid hourly space velocity of all raw materials entering the reactor is usually between 0.1 and 50 hr ^-1 , preferably between 0.2 and 50 hr -1
5hr ^-1 . The molar ratio of ethylene glycol:water:tertiary olefin is usually about 0.1 to 20:0.
-10:1, preferably about 0.2-10:0-0.8:1. The reaction pressure is usually 1 to 50 atm, preferably 2
~30 atm. If the reaction pressure is too low, part of the tertiary olefin as a raw material will vaporize, and if the pressure is too high, it is industrially disadvantageous in terms of equipment cost. The reaction temperature is preferably about 0 to 150°C, particularly about 40 to 130°C. If the temperature is too low, the reaction will not proceed sufficiently, and if the temperature is too high, the catalyst will be thermally damaged and the production rate of undesirable by-products such as olefin by-product oligomers and ethylene glycol dialkyl ether will increase.

When the reaction is carried out in this manner, the reaction mixture, that is, the crude ethylene glycol monotertiary alkyl ether that comes out of the reactor, contains, in addition to the target material MAE, usually unreacted tertiary olefin-containing or non-containing hydrocarbons, unreacted ethylene glycol, It contains a by-product oligomer of olefin, ethylene glycol ditertiary alkyl ether, a reaction solvent used as necessary, and a trace amount of acidic substance eluted from a strong acid type cation exchange resin catalyst. Also
If water is also present in the reaction system for the purpose of co-producing MAE and tertiary alcohol, the reaction mixture will contain the tertiary alcohol and unreacted water in addition to the above substances. . The purification process for obtaining the target MAE and tertiary alcohol from this reaction mixture and recovering ethylene glycol to be recycled to the reaction process will be described below.

In the purification process, well-known purification means such as extraction, distillation, extractive distillation, etc. are used. An example of a preferred method is to first separate the hydrocarbon fraction containing or not containing unreacted tertiary olefin in the first column, and then
By azeotropic distillation using azeotropic substances such as water using one or several distillation columns, a part of MAE, tertiary alcohol, by-product oligomer of olefin, by-product ethylene glycol dialkyl ether, etc. are extracted as an azeotropic mixture. It is separated from the top of the column, and a residue consisting mainly of MAE and ethylene glycol is obtained from the bottom of the column.
This residue is separated in a finishing rectification column, and the target high-purity MAE is recovered from the top of the column, and ethylene glycol is recovered from the bottom of the column. The first column may be a pressure distillation. Since most of the olefin by-product oligomers are dimers, they may be separated in the first column, or may be separated by providing a distillation column between the azeotropic distillation column and the first column. A preferred second purification method uses water as an aqueous extraction solvent, extracts MAE, ethylene glycol, and tertiary alcohol by extracting the reaction mixture with water, and distilling this extract to obtain the product MAE. This is a method to recover ethylene glycol, which is obtained and recycled. Unreacted tertiary olefin-containing or non-containing hydrocarbons and olefin by-product oligomers may be separated by distillation prior to extraction. Purification methods such as extraction, distillation, and extractive distillation are selected according to conventional methods to obtain high-purity target material MAE from the reaction mixture.
Any method may be used as long as it can obtain ethylene glycol and recover ethylene glycol for circulation to the reaction process.

Wetted parts of such purification processes (distillation columns, piping, etc.)
It is advantageous to use ferrous materials such as iron, carbon steel, and iron-containing alloys for intermediate tanks, etc.; Iron content in amounts ranging from ppm to 100% is mixed in, and if this is recycled to the reaction process as it is, it will cause deterioration of catalyst activity and clogging of the catalyst bed. According to the first invention, iron content is removed by vaporizing the ethylene glycol in the distillation column bottom residue, which is recovered ethylene glycol, before recycling the distillation column bottom residue as part of the reaction raw material. The feature is that after removal, it is recycled and used as part of the reaction raw material. A preferred example of the vaporization method is simple distillation, but methods that provide similar effects, such as a distillation method that involves some rectification, or a method that uses the extraction section of the recovered ethylene glycol separation column in the above-mentioned purification process, can also be used. It is also possible to adopt a method that provides the same effect without adding a new simple distillation device by using a side cut one or several stages above the bottom of the column rather than the bottom of the column. In addition, before performing simple distillation on recovered ethylene glycol, if other components that may be recycled into the raw material, such as a part of MAE or by-product ethylene glycol dialkyl ether, contain impurities such as iron that degrade the catalyst. It is preferable to mix these with recovered ethylene glycol and then perform simple distillation treatment. Other examples of simple distillation and similar effects include simple evaporation cans and film evaporators. Any apparatus, type, or method may be used as long as it includes a unit operation in which ethylene glycol mixed with iron is vaporized at least once.
The operating conditions may be atmospheric distillation or vacuum distillation (the boiling point of ethylene glycol is 196 to 198°C under normal pressure, e.g. 139°C under reduced pressure of 100 mmHg), and the vaporized ethylene glycol is usually condensed and recycled to the reaction process. .

The above reaction mixture contains trace amounts of acidic substances eluted from the strong acid type cation exchange resin catalyst, and when this reaction mixture is purified in a purification process using equipment made of glass lining or titanium, for example, MAE and tertiary alcohols are considerably decomposed and lost. According to the second invention, it is based on the fact that iron mixed in the recovered ethylene glycol is extremely effective as a method of suppressing the activity of eluted acid. The method is characterized in that at least a part of the residual iron-containing residue after vaporizing the iron or the fraction containing iron-containing impurities obtained in the refining process is mixed into the reaction mixture or crude MAE exiting the reactor for purification. . Therefore, for example, some of the recovered ethylene glycol may be purified by mixing it into the reaction mixture prior to the simple distillation process for recycling, or the residues from the simple distillation process (ethylene glycol, ethylene glycol oligomers, small amounts (consisting of iron content, etc.) may be mixed into the reaction mixture for purification. It is particularly effective if the amount of iron mixed into the reaction mixture is at least equivalent to the acidic substance, and the amount of iron eluted into the liquid in the system increases with time, so the amount of iron mixed in the acidic substance is usually Exists in an equivalent amount or more relative to the substance. The amount of iron added is usually about 10 ^-6 chemical equivalents or more, preferably about 10 ^-5 chemical equivalents or more, based on the reaction mixture or crude MAE1.

Although it is not as effective as the mixed iron dissolved in ethylene glycol, suppression of the decomposition of MAE and tertiary alcohol can also be achieved by using refining process equipment made of iron materials. In this case, suppression of decomposition can be further improved by mixing a basic substance such as ammonia or sodium hydroxide into the reaction mixture for purification.

Next, one embodiment of the present invention will be described with reference to the drawings. The figure is a general system diagram, in which 1 is a reaction column, 2 is a first distillation column, 3 is a second distillation column, 4 is a third distillation column, 5
is a fourth distillation column, 6 is a simple distiller (flash evaporator), 7 is a liquid-liquid separation tank, and 8, 9, and 10 are all heat exchangers. In the figure, tertiary olefin or a hydrocarbon mixture containing tertiary olefin is supplied via line 11, ethylene glycol is supplied via line 12, and if necessary, a portion of the tertiary olefin is supplied via line 32. Collected items may be reused. Ethylene glycol recovered from the purification process is recycled through the pipe 27. These raw materials are mixed and heated to a predetermined temperature in a heat exchanger 8, and then introduced into a reaction tower 1 made of an acid-resistant material such as stainless steel and filled with a strong acid type cation exchange resin catalyst. The reaction mixture leaving the reaction column 1 is
If necessary, a part of the raw material may be circulated through the pipe 14 for the purpose of removing reaction heat, stirring effect, etc., joining with the new raw material, and returning to the reaction tower 1. The rest of the reaction mixture is introduced into the distillation column 2 via line 15, from the top of the column through line 16 tertiary olefin or a tertiary olefin-containing hydrocarbon mixture is recovered, and from the bottom of the column other crude ethylene is recovered. Glycol monotertiary alkyl ether is in conduit 1
7 and introduced into the distillation column 3. In the distillation column 3, extractive distillation is carried out in the presence of water added from pipes 19 and 33, and a copolymer consisting of by-product oligomers of tertiary olefin, ethylene glycol ditertiary alkyl ether, MAE and water is distilled from the top of the column. A boiling mixture is distilled out, which is cooled and liquefied in a heat exchanger 10 and then passed from a pipe 18 to a liquid-liquid separation tank 7.
It is separated into an oil layer and an aqueous layer. water and
The aqueous layer consisting of MAE is transferred to the distillation column 3 via pipe 19.
The oil layer is partially refluxed to the top of the pipe 36.
The remaining part is introduced into the distillation column 5 through the pipe line 20. MAE in distillation column 5
The column overhead fraction containing 20% is mixed with the raw material of the distillation column 3 through pipe 21 and redistilled, and the column bottom residue of by-product ethylene glycol dialkyl ether is mixed with the raw material of distillation column 3 through pipe 21 and is redistilled.
2, and if necessary, part or all of this may be mixed with the recovered ethylene glycol in line 25 through line 30 and returned to the reaction process.
A residue consisting mainly of MAE and ethylene glycol is withdrawn from the bottom of the distillation column 3 via a line 23 and fed to the distillation column 4. In the finishing distillation column 4, high purity of the target product is obtained from the top of the column through a pipe 24.
The MAE product is obtained and the ethylene glycol is recovered from the bottom via line 25. Several ppm to several thousand ppm of iron is mixed in the recovered ethylene glycol, and in the present invention, rather than being recycled directly to the reaction process, it is introduced into the simple distiller 6 through the pipe 26, where it is vaporized. The fraction containing no iron is mixed with fresh ethylene glycol through the pipe 27 and recycled. The iron-containing residue is withdrawn from line 28.

Further, according to the second invention, a part of the iron-containing recovered ethylene glycol obtained from the bottom of the distillation column 4 or a part or all of the residue of the simple still 6 is transferred to the pipe 31 or 29, respectively. Therefore, the MAE decomposition activity of the acid eluted from the catalyst mixed in the reaction mixture can be suppressed. 3
4 and 35 are valves provided in the pipe lines 29 and 31, respectively.

If you want to co-produce tertiary alcohol with MAE, as shown in the figure, ethylene glycol and water are supplied from pipe 12, and from the top of distillation column 2, tertiary olefin or tertiary olefin-containing hydrocarbon is produced together with tertiary alcohol. It is also possible to recover the primary alcohol and recover the tertiary alcohol in another distillation column not shown in the figure, but generally speaking, as described above, the distillation column 3 is used to recover the tertiary alcohol.
Tertiary alcohol is also distilled out as an overhead fraction of
Purification and separation is performed using a suitable distillation means (not shown).

According to the present invention, the iron content can be completely removed from recovered ethylene glycol containing iron by simple vaporization treatment such as simple distillation, and even if the ethylene glycol treated in this way is recycled to the reaction process, there is no decrease in catalytic activity. Therefore, it has become possible to produce ethylene glycol monotertiary alkyl ether in high yield through long-term continuous operation. Furthermore, by utilizing this iron content, loss due to decomposition of MAE during the refining process can be extremely effectively prevented from the beginning of operation. This method of using iron as a decomposition inhibitor is different from the new addition of basic substances.
Since the method merely reuses the components originally present in the system, there are no problems with the removal of generated salts or excessive addition, and in that sense, it is extremely practical and industrially advantageous.

Next, the present invention will be explained with reference to Examples and Comparative Examples.

Example 1 Ethylene glycol monotertiary production from isobutylene and ethylene glycol according to the system diagram
Butyl ether was produced. The reaction column 1 was filled with strong acid type cation exchange resin catalyst Amberlyst 15 (average particle size 0.5 mmφ, manufactured by Rohm and Haas), and the reaction temperature was 60°C and the pressure was 20 kg/cm ² to react with 1.8
Kg/hr of ethylene glycol and 3.1 Kg/hr of C ₄ fraction (produced by fluid catalytic cracking method, isobutylene content 18 mol %) were introduced. The isobutylene:ethylene glycol molar ratio was 1:2.7 and the liquid hourly space velocity was 0.5 hr ^-1 . The amount of reaction mixture in pipe 15 obtained from reaction column 1 is 4.9Kg/
hr, and the composition (mol%) of the remaining crude ethylene glycol monotert-butyl ether fraction from which 2.6 Kg/hr of the _C4 fraction was removed is diisobutylene.
0.1%, ethylene glycol di-tert-butyl ether 4.1%, ethylene glycol mono-tert-butyl ether 21.5%, ethylene glycol mono-secondary butyl ether 0.1%, ethylene glycol 74.1%, other 0.1 mol%, and eluted acidic substances 5× It contained 10 ^-5 chemical equivalents/Kg. The conversion rate of isobutylene was 81%, the conversion rate of ethylene glycol was 26%, and the selectivity of ethylene glycol monotert-butyl ether (based on ethylene glycol) was 83%.

0.13 Kg/hr of recovered ethylene glycol, which will be described later, was mixed into this reaction mixture through pipe 31 (valve 35 was opened and valve 34 was closed), and then treated according to the system diagram in a refining process mainly consisting of carbon steel. . Substantially no decomposition of ethylene glycol monotert-butyl ether occurred. Purity from line 24
99% product ethylene glycol monotertiary
0.7Kg/hr of butyl ether was obtained.

530 ppm iron from pipe 25 (analyzed as iron)
1.3 kg/hr of recovered ethylene glycol was recovered. This 10% by weight was added to the pipe 31 as described above.
While the reaction mixture was mixed in, the remainder was subjected to normal pressure simple distillation in a simple distiller 6 to obtain a recovered ethylene glycol fraction with a yield of 97% and an iron content of 1 ppm or less. This was mixed with fresh ethylene glycol and recycled, but no deterioration was observed in the activity of the catalyst in reaction column 1 even after six months of continuous use.

Comparative Example 1 Ethylene glycol monotert-butyl ether was produced in the same manner as in Example 1, except that instead of vaporization using the simple distiller 6, filtration was performed using a Millipore membrane with a pore size of 1.0 microns. The recovered ethylene glycol that has undergone filtration still contains 10 ppm of iron, and 40
After continuous operation for days, the catalytic activity of reaction column 1 was 70% of the initial level.
It declined to .

Example 2 Ethylene glycol monotert-butyl ether was produced in the same manner as in Example 1, except that the valve 35 was closed and the recovered ethylene glycol was not mixed into the reaction mixture through the line 31. Some decomposition of ethylene glycol monotert-butyl ether occurred during the purification process, and the amount of product ethylene glycol monotert-butyl ether produced decreased to 93% of that in Example 1. No decrease in catalyst activity was observed.

Comparative Example 2 The reaction mixture obtained in Example 1 was mixed with enough water to completely azeotrope the isobutylene polymer and ethylene glycol di-tert-butyl ether therein, and a glass plate having 20 theoretical plates was prepared. Continuous atmospheric extractive distillation was carried out in a distillation column under conditions of a top temperature of 99°C, a bottom temperature of 170 to 176°C, and an average residence time of 2 hours. As a result, the ethylene glycol monotertiary contained in the reaction mixture was extracted. 20% of the butyl ether was decomposed. The decomposition rate is considerably higher than in Example 2.

Example 3 Ethylene glycol monotert-butyl ether and tertiary butyl alcohol were produced from isobutylene, ethylene glycol and water according to the system diagram. Amberlyst 15 in reaction column 1
The reaction temperature is 60℃ and the pressure is 20 atm.
1.9 Kg/hr of ethylene glycol, 0.25 Kg/hr of water, and 14.4 Kg/hr of fluid catalytic cracking _C4 fraction (isobutylene content 17.5%) were introduced. The amount of reaction mixture in line 15 obtained from reaction column 1 is 16.6Kg/hr
The composition of the remaining crude ethylene glycol monotert-butyl ether after removing 12.6Kg/hr of the _C4 fraction is diisobutylene 0.002Kg/hr, tertiary butyl alcohol 0.63Kg/hr, and ethylene glycol ditertiary ether. Butyl ether 0.31Kg/
hr, ethylene glycol monotertiary butyl ether 2.28Kg/hr, ethylene glycol 0.67
Kg/hr, water 0.10 Kg/hr, and the content of acidic substances was 2.5×10 ^-4 chemical equivalent/Kg. Conversion rate of isobutylene 68.2%, conversion rate of ethylene glycol
The conversion rate of water was 60.9%, and the selectivity of ethylene glycol monotert-butyl ether (based on isobutylene) was 83%.

This reaction mixture is mixed with 0.18 kg/hr of recovered ethylene glycol containing 460 ppm of iron through line 31 (valve 35 is open and valve 34 is closed), and then processed according to the system diagram in a refining process consisting mainly of carbon steel. did. The yield of the product ethylene glycol monotertiary butyl ether was 2.2 Kg/hr, and the yield of the product tertiary butyl alcohol was 0.62 Kg/hr. The amount of recovered ethylene glycol containing 460 ppm of iron from pipe 25 is 0.8 kg/hr, and this is distilled in a single still 6 under a reduced pressure of 100 mmHg.
Distillation was performed at ℃ to obtain a recovered ethylene glycol fraction with a yield of 98% and an iron content of less than 1 ppm. This was mixed with new ethylene glycol and used for circulation.
Even after three months of continuous operation, the activity of the catalyst in reaction column 1 showed no deterioration at all. Substantially no decomposition of ethylene glycol monotert-butyl ether and tertiary butyl alcohol occurred during the purification process.

Example 4 In place of the _C4 fraction, 25 mol/hr of isoamylene and 24.7 mol/hr of ethylene glycol were used, and the reaction conditions were a temperature of 80°C, a pressure of 20 atm, and a liquid hourly space velocity of 0.96 hr ^-1 . Ethylene glycol monotert-bentyl ether was produced from isoamylene and ethylene glycol in the same manner as in Example 1 except for this.

The yield of ethylene glycol monotertiary pentyl ether is 62.4 based on ethylene glycol.
%, 63.2% based on isoamylene, ethylene glycol conversion rate is 70%, isoamylene conversion rate is 79
%, ethylene glycol monotertiary
Pentyl ether selectivity (isoamylene standard)
was 80%. After removing isoamylene from the reaction mixture, the remaining crude ethylene glycol monotertiary pentyl ether has a composition of 0.4 mol% isoamylene dimer, 7.3 mol% ethylene glycol ditertiary pentyl ether, and 62.0 mol% ethylene glycol monotertiary pentyl ether. mol%, and ethylene glycol was 30.3 mol%.
No decrease in catalyst activity was observed during 30 days of continuous operation, and no decomposition of ethylene glycol monotertiary pentyl ether was observed during the purification process.

Example 5 Ethylene glycol monotert-butyl ether was produced from ethylene glycol and isobutylene in the same manner as in Example 1 except that valve 35 was closed and valve 34 was opened. No decrease in catalyst activity was observed during continuous operation, and no decomposition of ethylene glycol monotert-butyl ether was observed during the purification process.

[Brief explanation of the drawing]

The figure is a schematic system diagram illustrating one embodiment of the method of the present invention. 1... Reaction column, 2, 3, 4, 5... Distillation column, 6
...Single distiller, 7...Liquid-liquid separation tank.

Claims (1)

[Scope of Claims] 1. Ethylene glycol and tertiary olefin are caused to react by passing the ethylene glycol and tertiary olefin through a fixed bed filled with a strong acid type cation exchange resin catalyst, and the reaction mixture is passed through a distillation means. When refining to obtain high-purity ethylene glycol monotertiary alkyl ether in a refining process involving Prior to recycling ethylene glycol as part of the reaction raw material, the ethylene glycol contained in the bottom residue of the distillation column is vaporized to remove iron-based impurities, and then recycled as part of the reaction raw material. A method for producing ethylene glycol monotertiary alkyl ether, characterized by: 2. Ethylene glycol and tertiary olefin are caused to react by passing through a fixed bed filled with a strong acid type cation exchange resin catalyst, and this reaction mixture is purified in a purification process including distillation means. When obtaining high-purity ethylene glycol monotertiary alkyl ether, at least a part of the equipment for the refining process is made of iron material, and the ethylene glycol recovered as the distillation column bottom residue in the refining process is used as a reaction raw material. Prior to recycling as a part of the residue, ethylene glycol contained in the bottom residue of the distillation column is vaporized to remove iron-based impurities, and then recycled as a part of the reaction raw material, and the bottom of the distillation column is recycled. At least a portion of the residual iron-containing residue obtained by vaporizing ethylene glycol from the residue or the fraction containing iron-containing impurities obtained in the purification process is converted into the reaction mixture or crude ethylene glycol monotertiary alkyl leaving the reactor. A method for producing ethylene glycol monotertiary alkyl ether, which comprises mixing it in ether and purifying it to obtain ethylene glycol monotertiary alkyl ether.