KR100348988B1 - Process for producing diarylethane having high quality - Google Patents

Abstract

The present invention relates to a method for preparing high purity diaryl ethane, and more particularly, to removing styrene and other olefins, which are responsible for the reaction process of alphamethylbenzyl alcohol and aromatic hydrocarbon under the solid acid catalyst and lowering the yield of the diaryl ethane product. The present invention relates to a process for producing at least 99% high-purity diaryl ethane consisting of a hydrogenation reaction process, an unreacted aromatic hydrocarbon recovery process, an impurity purge method such as C6 to C9 naphthene, and a diaryl ethane separation process. .

Description

Process for producing diarylethane having high quality

The present invention relates to a method for preparing high-purity diarylethane (hereinafter referred to as 'DAE'), more specifically alpha-methylbenzyl alcohol (hereinafter referred to as 'MBA') and benzene, DAE is synthesized by reacting one or more aromatic hydrocarbons selected from the group consisting of toluene, ethylbenzene, ortho-xylene, meta-xylene, para-xylene, and trimethylbenzene under a solid acid catalyst, The present invention relates to a process for producing high purity DAE of 99% or more by removing impurities.

In general, DAE is a high boiling point solvent used as a pressure-sensitive paper solvent, a plastic plasticizer, and a heat medium oil. In the first method, DAE is prepared by reacting styrene with an alkylbenzene mixed fraction having 6 to 9 carbon atoms under a catalyst. In Japanese Patent Laid-Open No. 4-257530 and Japanese Patent Laid-Open No. 48-97858, sulfuric acid is used as a catalyst, but there are problems such as separation and recovery of sulfuric acid and corrosion of equipment compared to the advantage of obtaining a relatively good quality product. U.S. Patent No. 5,068,482 and U.S. Patent No. 5,866,733 describe a method for producing DAE by reacting under a zeolite catalyst, which facilitates the recovery of the product and no device corrosion problems. However, the above methods using styrene as a raw material have to dilute styrene to prevent side reactions in which styrene is converted into oligomers during the reaction, and the reactor injection rate must be very slow to keep the concentration of styrene in the reactor very low. Not suitable for production

The second method is a method proposed in Korean Patent Application No. 98-1061, which is a method of preparing DAE by reacting MBA with an aromatic hydrocarbon under a solid acid catalyst. This method has no device corrosion problems and does not use styrene, which causes side reactions, as a raw material, providing a relatively high conversion and yield. However, olefin components such as styrene, which are partially produced by side reactions during the reaction, are recycled to the reactor, which drastically degrades the activity of the reactor, and there is a difficulty in separation and purification, thereby causing a problem in designing a commercial process.

Accordingly, the present inventors have conducted extensive research to solve the above problems, and as a result, in the method for producing DAE by reacting MBA with an aromatic hydrocarbon under a solid catalyst, olefin components such as styrene, which is a problem in the design of a commercial process, are hydrogen. A method of removing by addition reaction and effectively separating and purifying DAE through two distillations was found, and the present invention was completed based on this.

Accordingly, an object of the present invention is to prepare a DAE by reacting MBA with an aromatic hydrocarbon under a solid catalyst, and to remove olefin components such as styrene, which is a problem in designing a commercial process, and to effectively separate and purify DAE. To provide.

In the method of the present invention for achieving the above object in the production method of high purity diarylethane,

a) synthesizing diarylethane by reacting alphamethylbenzyl alcohol and an aromatic hydrocarbon in a volume ratio of 1: 5-20 in the presence of a solid acid catalyst;

b) removing the water contained in the reactants;

c) in the presence of a metal catalyst, introducing hydrogen into the effluent from which the water has been removed to remove styrene and other olefin components in the effluent by hydrogenation;

d) recovering the oil containing 90% or more of the unreacted aromatic hydrocarbon from the reactant and supplying it to the diaryl ethane reaction in step a), and distilling the concentrated fraction of the remaining diaryl ethane to boiling point than the diaryl ethane. Removing this low component; And

e) removing the component having a higher boiling point than diarylethane by distilling the first distilled concentrated fraction.

1 is a view schematically showing a process for producing a diarylethane according to the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

As described above, FIG. 1 schematically illustrates a DAE manufacturing process according to the present invention, wherein MBA and benzene, toluene, ethylbenzene, ortho-xylene, meta-xylene, para-xylene and trimethylbenzene One or more aromatic hydrocarbons selected from the group consisting of are added to the DAE reactor loaded with the solid acid catalyst and reacted. At this time, the aromatic hydrocarbon concentrated fraction recovered from the aromatic hydrocarbon recovery tower is also supplied. The solid acid catalyst may be Y-type zeolite, X-type zeolite, zeolite beta (β), mordenite, L-type zeolite, ZSM-5, ZSM-11, ZSM-18, ZSM-12, magnesite, or off-rectite. Zeolite catalyst system, MCM-41, KIT-1, KIT-2, AIKIT-3, clay, and one selected from the group consisting of silica-alumina. MBA and aromatic hydrocarbons are supplied in a volume ratio of 1: 5 to 20, and in order to increase the smooth flow and reactivity of the oil in the DAE reactor, 100 to the amount of raw material to which hydrogen or nitrogen is added does not participate in the reaction. Feed at 400 times volume. The reaction temperature of the DAE reactor is 100 to 300 ° C., preferably 150 to 250 ° C., when the reaction temperature is less than 100 ° C., the reaction is less likely to occur, and when it exceeds 300 ° C., the side reaction of MBA becomes active to shorten the catalyst life and Resulting in lower yield.

The reaction pressure of the DAE reactor is 1 to 45 kg / cm 2 G, preferably 15 to 25 kg / cm 2 G. When the pressure is less than 1 kg / cm 2 G, the reaction is less likely to occur. Side reactions are aggravated.

DAE reactor effluent contains 0.01 to 2% by weight of styrene produced as a side reaction depending on the state of the catalyst, and if the styrene is not removed, the styrene is included in the aromatic hydrocarbon concentrated fraction recovered from the aromatic hydrocarbon recovery tower. Will be recycled. In this case, styrene is rapidly concentrated in the DAE reactor, causing problems such as a decrease in DAE yield and an increase in side reactions.If the styrene concentration exceeds a certain amount, deactivation of the catalyst due to oligomer formation rapidly progresses the process operation. Lose. Therefore, styrene should be removed by hydrogenation at the rear end of the DAE reactor, and hydrogenation is performed by supplying hydrogen to the DAE reactor effluent. DAE reactor effluent contains olefin components with distillation range similar to DAE in addition to styrene, which do not affect the DAE production reaction, but are difficult to obtain high purity DAE products, and therefore are removed from the hydrogenation reactor with styrene must do it. In particular, since these olefin components are converted to DAE products after hydrogenation, DAE yield is also increased.

The hydrogenation reaction uses a catalyst containing a metal component, and the catalyst is selected from the group consisting of nickel, palladium and platinum, and is preferably nickel. The metal component may be present in a form supported on a solid carrier, and examples of the support include zeolite, alumina, silica, or silica alumina. The operating temperature is 40 to 150 ° C., preferably 60 to 120 ° C., the operating pressure is 1 to 20 kg / cm 2 G, preferably the pressure is 5 to 15 kg / cm 2 G, and the hydrogen and olefin ratio is 2 in molar ratio. It is -15: 1, Preferably it is 2-10: 1. If the operating temperature is less than 40 ° C., the pressure is less than 1 kg / cm 2 G, and the hydrogen and olefin ratio is less than 2: 1 in molar ratio, the reaction does not occur well, and the operating temperature exceeds 150 ° C. and the pressure If the ratio exceeds 20 kg / cm 2 G and the hydrogen-olefin ratio exceeds 15: 1 in molar ratio, the hydrogenation reaction of not only olefins but also aromatic components such as DAE and aromatic hydrocarbons occurs simultaneously.

The DAE reactor effluent contains about 1 to 2% by weight of the water produced in the reaction, and this water affects the operation of the hydrogenation reactor and the aromatic hydrocarbon recovery tower, so it is separated from the separator before being sent to the hydrogenation reactor. Should be. The DAE reactor effluent is at a high temperature of about 200 ° C. and is cooled to about 50 ° C. at the front of the separator, condensing most of the components except hydrogen or nitrogen introduced for smooth flow of oil inside the reactor. At this time, since the effluent of the DAE reactor except for water and water is not mixed, the delamination occurs, and the water separated in the lower part is removed, and hydrogen or nitrogen remaining without condensation is recovered and returned to the DAE reactor.

After removing the olefin components such as styrene through the hydrogenation reactor, the hydrogenation reactor effluent is sent to an aromatic hydrocarbon recovery tower. The aromatic hydrocarbon recovery tower is a process for recovering the excess aromatic hydrocarbon, which is operated at a temperature of 100 to 250 ° C. and a pressure of 0.1 to 5 kg / cm 2 G.

Most of the aromatic hydrocarbon concentrate recovered from the aromatic hydrocarbon recovery tower is mixed with the newly supplied aromatic hydrocarbon fraction at the front of the DAE reactor and fed to the reactor, and some of it is purged to the outside to prevent accumulation of C6 to C9 naphthene components. Let's do it. Some of the C6 to C9 naphthenes are included in the newly supplied aromatic hydrocarbons, but most of them are produced by side reactions in the hydrogenation reactor, and are contained in about 0.1 to 2% by weight depending on the reaction conditions of the hydrogenated reactor effluent. When accumulated in the process, it does not affect the activity of the DAE reaction catalyst, but lowers the DAE yield and selectivity.

The aromatic hydrocarbon recovery column bottoms produce DAE-concentrated fractions, which can be fed directly to the DAE separation tower or collected in a storage tank for increased throughput and operating efficiency. The DAE separation column is usually composed of two distillation columns, and the lower boiling point component than the DAE is removed from the top of the first distillation column, and the higher boiling point component than the DAE is separated from the bottom of the secondary distillation column so that the high concentration of DAE is 2 It is prepared in the top of a tea distillation column. The primary distillation column is operated at a temperature of 100 to 350 ° C. and a pressure of 0.2 to 1 kg / cm 2 G, and the secondary distillation column is operated at a temperature of 200 to 350 ° C. and a pressure of 0.1 to 0.8 kg / cm 2 G.

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

Example

Example 1

Phenyl Xylyl Ethane (hereinafter referred to as 'PXE') filled with silica alumina solid acid catalyst was charged with 1200 Nm3 / hr of 80% pure hydrogen at a temperature of 200 ° C and a pressure of 21 kg / cm2G. , A mixture of ethylbenzene, ortho-xylene, meta-xylene, para-xylene and MBA in a volume ratio of 10: 1 was supplied at 11500 kg / hr to react. After the water was removed from the effluent of the PXE reactor, it was fed to a hydrogenation reactor loaded with a catalyst loaded with 15% by weight of nickel on an alumina carrier, and hydrogen was supplied at 5 kg / hr with a purity of 80%. The reaction was carried out at a temperature of 80 ° C. and a pressure of 5 kg / cm 2 G. The hydrogenation reactor effluent was fed to the xylene recovery tower at 11300 kg / hr, 470 kg / hr of the recovered mixed xylene concentrate fraction was purged and the remaining fraction was fed back to the PXE reactor. At this time, the xylene recovery column was operated at a column top pressure of 1 kg / cm 2 G from a column bottom temperature of 240 ° C. to a column top temperature of 140 ° C. and a column bottom pressure of 2 kg / cm 2 G. The mixed xylene concentrate was recovered and the remaining PXE component was sent to a storage tank for storage. By supplying the stored oil to the PXE separation tower 3500kg / hr, 99.7% high-purity PXE was produced, wherein the primary separation tower of the PXE separation tower from the bottom temperature 300 ℃ to the top temperature 140 ℃ and 0.9 kg top pressure The tower separation pressure was operated at 0.3 kg / cm2G at / cm2G, and the secondary separation column was operated at the bottom temperature of 310 ° C to the tower temperature of 240 ° C and the tower static pressure at 0.2kg / cm2G at the tower bottom pressure of 0.7kg / cm2G. .

The composition of the main components of each process step was analyzed by gas chromatography and the change is shown in Table 1 below.

PXE Reactor Raw Material PXE Reactor Effluent Hydrogenation reactor effluent Recovered Xylene Concentrate Xylene Recovery Tower Top Oil High Purity PXE Products Hydrogen 0.82 0.83 0.01 0.00 0.00 0.00 water 0.13 1.32 0.09 0.09 0.00 0.00 toluene 0.04 0.04 0.04 0.05 0.00 0.00 C8 naphthene 0.28 0.24 0.28 0.33 0.00 0.00 Ethylbenzene 21.48 20.20 21.00 24.04 0.20 0.00 Para-xylene 15.52 14.76 15.08 17.23 0.40 0.00 Meta-xylene 34.51 32.88 33.57 38.29 1.25 0.00 Styrene 0.00 0.09 0.00 0.00 0.00 0.00 Ortho-Xylene 17.77 17.74 18.10 19.58 7.98 0.00 Isopropylbenzene 0.39 0.49 0.50 0.39 1.24 0.00 Acetophenone 0.74 0.98 0.20 0.00 1.59 0.00 Alphamethylbenzyl alcohol 8.31 0.00 0.47 0.00 3.66 0.00 Phenyl xylylethane 0.00 8.99 9.86 0.00 77.32 99.97 High specific gravity material ^* 0.00 1.45 0.81 0.00 6.36 0.03 Sum 100.00 100.00 100.00 100.00 100.00 100.00

* Components having a higher boiling point than phenylxylylethane.

The unit of each component of the said Table 1 is weight%.

Examples 2-4

PXE reactor effluent contains olefins with distillation similar to styrene and PXE and must be removed from the hydrogenation reactor. In Table 2, the temperature 40 ℃, pressure 10 kg / ㎠G, the ratio of hydrogen and olefin shows the reaction results when the respective fractions reacted at 5: 1 in a molar ratio.

Example 2 Example 3 Example 4 DAE reactor effluent Hydrogenation reactor effluent DAE reactor effluent Hydrogenation reactor effluent DAE reactor effluent Hydrogenation reactor effluent Ethylcyclohexane 0.13 0.17 0.12 0.13 0.12 0.12 Ethylbenzene 21.05 21.0 20.75 21.67 20.91 21.88 Para-xylene 25.1 24.9 25.0 25.0 25.4 25.2 Meta-xylene 26.1 26.0 25.52 25.55 25.56 25.45 Styrene 0.02 0 0.82 0 1.17 0 Ortho-Xylene 19.18 19.05 18.87 18.93 19.13 19.08 Acetophenone 0.89 0.29 0.86 0.27 0.85 0.32 Alphamethylbenzyl alcohol 0 0.55 0 0.59 0 0.54 Phenyl xylylethane 5.82 6.89 6.34 6.65 4.93 6.35 High specific gravity material ^* 1.06 0.51 1.17 0.51 1.31 0.42 Sum 99.35 99.36 99.45 99.3 99.38 99.36

* Components having a higher boiling point than phenylxylylethane.

The unit of each component in Table 2 is weight percent, and the rest are unmeasurable components.

Table 2 shows the degree of removal of some olefin components of the styrene and the high specific gravity material to be removed in the hydrogenation reactor, it can be seen that the styrene is all removed even when the concentration is increased to 1.17% by weight.

Example 5

Some of the fraction recovered from the aromatic hydrocarbon recovery tower was purged to remove impurities such as C8 naphthenes from the hydrogenation reactor effluent. In Table 3 below, the C8 naphthene component content contained in the raw material is 0.12% by weight, and the C8 naphthene component accumulated in the process is continuously purged under operating conditions of which the content is increased by 0.04% after passing through the hydrogenation reactor. Is the final concentration.

Example 5 Fuzzy Method Continuous purge 1 ton per hour Initial concentration 0.12 result Gradually increases at initial concentration, then becomes constant at 0.54

The component unit in Table 3 above is weight percent.

As can be seen through the above examples, according to the method described in the present invention, olefin components such as styrene were removed, and the concentration of impurities accumulated in the process was lowered to a predetermined level or less, and thus stable process operation was performed. DAE products could be easily manufactured.

Claims (9)

In the manufacturing method of high purity diaryl ethane, a) synthesizing diarylethane by reacting alphamethylbenzyl alcohol and an aromatic hydrocarbon in a volume ratio of 1: 5-20 in the presence of a solid acid catalyst; b) removing the water contained in the reactants; c) in the presence of a metal catalyst, introducing hydrogen into the effluent from which the water has been removed to remove styrene and other olefin components in the effluent by hydrogenation; d) recovering the oil containing 90% or more of the unreacted aromatic hydrocarbon from the reactant and supplying it to the diaryl ethane reaction in step a), and distilling the concentrated fraction of the remaining diaryl ethane to boiling point than the diaryl ethane. Removing this low component; And e) a second distillation of the first distilled concentrated fraction to remove components having a higher boiling point than diarylethane. The method of claim 1, wherein step d) further comprises purging a portion of the aromatic hydrocarbon concentrate fraction recovered to prevent accumulation of C6 to C9 naphthenic components. The method of claim 1, wherein the aromatic hydrocarbon is one or more selected from the group consisting of benzene, toluene, ethylbenzene, ortho-xylene, meta-xylene and para-xylene. Manufacturing method. The method of claim 1, wherein step b) is characterized in that the water affecting the operation of the hydrogenation reactor and the aromatic hydrocarbon recovery tower is separated by cooling and bed separation. According to claim 1, wherein the hydrogenation reaction 2 to 15 mol of hydrogen per 1 mol of the olefin component having a distillation range similar to the styrene and diaryl ethane contained in the effluent in a temperature of 40 to 150 ℃ Characterized in that under a pressure of 1 to 20 kg / cm 2 G. The method according to any one of claims 1 to 5, wherein the hydrogenation is carried out in the presence of one or two or more metal catalysts selected from the group consisting of nickel, palladium and platinum. The method of claim 1 wherein the aromatic hydrocarbon is recovered at a temperature of 100-250 ° C. and a pressure of 0.1-5 kg / cm 2 G. The method according to claim 1, wherein the first distillation is performed at a temperature of 100 to 350 ° C and a pressure of 0.2 to 1 kg / cm 2 G. The method according to claim 1, wherein the second distillation is performed at a temperature of 200 to 350 ° C and a pressure of 0.1 to 0.8 kg / cm 2 G.