JPS602288B2 - Method for decomposing and recovering ethylbenzene residual oil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention deals with the production of ethylbenzene residual oil (also called ethylbenzene heavy end) that is created when ethylbenzene is produced from benzene and ethylene.

) is decomposed and then advantageously recovered as benzene, toluene, ethylbenzene and/or styrene. Generally, ethylbenzene is synthesized by reacting benzene and ethylene in the presence of a catalyst such as aluminum chloride, but a large amount of ethylbenzene residual oil is produced as a by-product. The properties of such ethylbenzene kerosene vary depending on the ethylbenzene manufacturing process, distillation conditions, etc., but typical properties are as follows. Note that the measurements were conducted in accordance with JIS. Properties of ethylbenzene pickling oil [11 Specific gravity (15/4℃) 0.95
~1.0■ Viscosity (RW seconds, 50qo)
30~50'31 Distillation properties Total distillation base
90~Satoshi Capacity% First Station Point 20
0-35 and 050% distillation point 250
~370pm ○Final station 300~
39pi0 Such ethylbenzene pickled oil has been used only as a secondary fuel oil, but the present invention decomposes such ethylbenzene residual oil, which has little utility value, and uses it as raw material for chemical industry, etc. The purpose of this project is to advantageously recover various aromatic hydrocarbons that have high utility value, and contribute to the rationalization of styrene production and, by extension, the petrochemical industry.

The method for decomposing and recovering ethylbenzene residual oil of the present invention involves decomposing and reacting ethylbenzene residual oil, which is split during the production of ethylbenzene from benzene and ethylene, in the presence of an acid catalyst, and then part of the decomposition products. Alternatively, this method is characterized in that the entire amount is supplied to a distillation system in the production of styrene from ethylbenzene and recovered as benzene, toluene, ethylbenzene and/or styrene.

When the method of the present invention is used, not only can penzene, toluene, ethylbenzene, styrene, etc. Since it is carried out in-system, the distillation equipment and distillation operation for the decomposition products can be simplified or omitted. In addition, since the decomposition product has a polymerization inhibitor, the effect of inhibiting styrene polymerization in a styrene distillation system can also be obtained. Next, an example of an embodiment of the present invention will be described based on the accompanying drawings.

The attached drawing shows an apparatus in which the method of the present invention can be employed in a typical styrene production process in which ethylbenzene is produced from benzene and ethylene using an aluminum chloride catalyst, and styrene is produced by a dehydrogenation reaction of the bound ethylbenzene. This shows a schematic layout of the entire structure. The main equipment in the diagram is as follows.

Ethylbenzene production equipment A: Benzene dehydration tower B: Ethylbenzene synthesis reactor C: Catalyst separation equipment D: Cleaning equipment E: Ethylbenzene distillation tower T,: Ethylbenzene storage tank T2: Ethylbenzene residual oil storage tank Styrene production equipment F: For styrene production Reactor (ethylbenzene dehydrogenation reactor) G: Oil-water separator H: Styrene distillation column Ethylbenzene residue oil cracking equipment J: Ethylbenzene residue oil distillation column K: Ethylbenzene residue oil cracking reactor L: Gas-liquid separator or , Lines with Arabic numerals from 1 to 32 in the figure all indicate pipelines, and each pipeline is used for introducing, transferring, or discharging various substances. This is done when explaining the process.

Further, dotted lines and broken lines in the figure indicate the state of communication between the pipelines, and arrows indicate the direction of flow of materials in the pipelines. First, raw material benzene is introduced from line 1, joins with benzene separated in distillation column E that refluxes through line 11, and is introduced into dehydration column A to an extent that does not adversely affect the ethylbenzene synthesis reaction (for example, water After being dehydrated to (weight ppm or less), it is introduced into reactor B through line 2 together with ethylene introduced through line 3. Benzene and ethylene are reacted in reactor B in the presence of an NC13 and HCI mixed catalyst supplied from line 4, and the reaction product is sent to catalyst separation device C via line 5. The catalyst separated from the reaction product in the catalyst separation device C is returned to the reactor 2 via line 6 and used for the reaction again, and the reaction product from which the catalyst has been separated is supplied to the cleaning device D via line 7. and washed (and neutralized) with a caustic soda aqueous solution or water supplied from line 8 in the device D.
be done. The cleaning waste water is discharged from the device D through line 9,
Further, the washed reaction product is supplied to the distillation column E via line 10. The reaction product is distilled in distillation column E and separated into unreacted benzene, ethylbenzene, created polyethylbenzene, ethylbenzene residual oil, etc., and the unreacted benzene passes through line 11 as described above and is synthesized with ethylbenzene together with raw benzene. Reflux the reaction. By-product polyethylbenzene is returned to reactor B via line 12 for recovery of ethylbenzene and the like by transalkylation reaction. Ethylbenzene is stored in storage tank T through line 13, and ethylbenzene residual oil is stored in storage tank T2 through line 14. The above ethylbenzene production method and apparatus are essentially the same as those used in conventional ethylbenzene production. The ethylbenzene in the storage tank T is taken out through line 15, refluxed through line 20, combined with ethylbenzene separated at the bottom of the distillation, and introduced into reactor F.

The ethylbenzene is mixed with steam introduced from line 16 in reactor F, and then subjected to a dehydrogenation reaction in the presence of a dehydrogenation catalyst (for example, an iron-based dehydrogenation catalyst) to be converted into styrene. The reaction product led out from reactor F through line 17 is introduced into the styrene distillation column via oil/water separator G and line 19. The water separated from the reaction product in the oil-water equipment G is discharged through line 18. The reaction products thus introduced into the styrene distillation column are distilled together with the ethylbenzene residual oil decomposition products introduced via lines 31 and 32, which will be described later, to produce benzene, toluene, ethylbenzene, and styrene. and styrene residual oil. Ethylbenzene is returned to reactor F through line 20 as described above, and benzene, toluene, styrene, and styrene residual oil are returned to reactor F through lines 21, 22, 23, and 24, respectively.
is retrieved by The above styrene production method and apparatus are essentially the same as those used in conventional styrene production, except that the ethylbenzene residual oil decomposition product is subjected to distillation treatment in the distillation equipment.

Then, the decomposition products of ethylbenzene residual oil are in line 3.
This is a unique structure based on the method of the present invention, in that it is introduced into the distillation column H' via 1 and 32 and subjected to distillation treatment. In the present invention, since the distillation of the ethylbenzene decomposition product is carried out in the distillation system used in styrene production, the distillation equipment and distillation operation for the decomposition product of the ethylbenzene residual oil can be omitted or simplified, and the decomposition product can be omitted or simplified. Benzene, toluene, ethylbenzene and/or styrene can be advantageously recovered from the product. In addition, when the decomposition products of ethylbenzene residual oil, especially the child crab fraction of the decomposition product, are fed to the styrene distillation column through the line 32, the residue contained in the child crab fraction is The oil exhibits a polymerization inhibiting effect even in the styrene distillation column H', and the effect of saving the use of polymerization inhibitor in the styrene distillation column H' can be obtained. The ethylbenzene pickling oil in the storage tank T2 is taken out via line 25 and supplied to the distillation column J.

Further, a liquid decomposition product produced in a decomposition reactor K, which will be described later, is also introduced into the distillation column J via a line 30. These introduced components are then subjected to fractional distillation in the distillation column J to produce a fraction lighter than C8 aromatics, a fraction heavier than C9 aromatics,
The crab fraction with a boiling point of about 350° C. or lower and the baby crab fraction with a boiling point of about 350° C. are separated and taken out from lines 31, 26 and 32, respectively. In addition, the highest boiling point of the crab material taken out from this line 26, that is, the above-mentioned approximately 350 qo
The temperature can be varied to some extent depending on the desired operating conditions. The fraction led out from the line 26 is supplied to the decomposition reactor K, where it comes into contact with a decomposition catalyst and undergoes a decomposition reaction.

As such a decomposition catalyst, an acid catalyst is usually used. Examples of acid catalysts include aluminum chloride, sulfuric acid, BF
3-Hiro○, phosphoric acid, silica/alumina, zeolite, and various other catalysts. The decomposition reaction may be carried out in any of the gas phase, liquid phase, or gas-liquid mixed phase. Furthermore, the decomposition reaction may be carried out in the presence of hydrogen, and in such a case, hydrogen is supplied to the decomposition reactor K from the line 27.
be provided. The decomposition products produced in the decomposition reactor K are introduced into the gas-liquid separator L via line 28.

The gas separated in the gas-liquid separator L is discharged through line 29, and the liquid decomposition products similarly separated are discharged through line 3.
It is supplied to the distillation column J through 0 and subjected to fractional distillation. Of course, if no gaseous substance is present, the gas-liquid separator L is not necessary. The C8 aromatic lighter fraction (top fraction) thus separated in the distillation column J and taken out from the line 31 is fed to the styrene distillation column and converted into benzene, toluene, ethylbenzene, and/or styrene, etc. It will be collected. In addition, the above-mentioned child fraction (column bottom crab fraction) with a boiling point of about 35 pi, which is taken out from line 32, is also supplied to the styrene distillation column together with/or separately from the above-mentioned line 31, and is contained in the crab fraction. The polymerization inhibitor is used as a polymerization inhibitor in a styrene distillation column. In addition, the decomposition reaction efficiency in the decomposition reactor K is high, and C
8 When only the aromatic crab fraction and the fraction with a boiling point of about 350° C. or higher are mainly obtained, the ethylbenzene residual oil decomposition product from line 28 or line 30 is processed without passing through distillation column J. It may also be fed directly to the styrene distillation column.

In addition, only the top fraction taken out through line 31 of distillation column J is fed to the styrene distillation column H', and the bottom fraction taken out through line 32 is operated without being supplied to the styrene distillation column. It is also possible to do so. The arrangement of the devices described above is an example of a typical arrangement, and the present invention is not limited to this example of arrangement.

Example 1 A case in which ethylbenzene was produced according to the ordinary aluminum chloride method using the apparatus shown in the attached drawings, and styrene was produced by dehydrogenation of the obtained ethylbenzene (however, the ethylbenzene residual oil was not decomposed). do not have.

), and the ethylbenzene residue oil with the following properties that developed dramatically in the ethylbenzene manufacturing process is decomposed under the following decomposition reaction conditions, and the decomposition product is supplied to the distillation system of the styrene manufacturing process and recovered. A comparison of 100 parts by weight of the by-product ethylbenzene residual groove oil used contained 15.2 parts by weight of benzene, 2.9 parts of toluene, 24.4 parts of ethylbenzene, and 0.0 parts of styrene.
The result was that 0 parts by weight could be recovered. 1 Properties of ethylbenzene clear oil Specific gravity (15/4℃) 0.98 Distillation properties Initial boiling point 260℃50
% distillation point 29 pi○ final distillation point
36 P0 all on base
96% Triethylbenzene, nutritious fraction 0% B Decomposition reaction conditions Reaction temperature 500℃ Reaction pressure 50X9/G space velocity (L
HSV) hr-IH2/Residual oil molar ratio: 10 mol Catalyst used
When the entire amount of silica/alumina decomposition reaction products was fed to the distillation column in this way, the amount of polymer produced after distillation was 2.6% by weight based on the styrene produced; If the product is not connected to the distillation column at all, the amount of the same polymer produced in the distillation column is 3. % by weight, indicating that the polymerization inhibitor in the decomposition product has an effect of inhibiting polymerization in the distillation column.

[Brief explanation of the drawing]

The attached drawing is a schematic layout of the entire apparatus that allows the method of the present invention to be employed in a method for producing ethylbenzene from benzene and ethylene and dehydrogenating the obtained ethylbenzene to produce styrene. be.

Claims (1)

[Claims] 1. Ethylbenzene residue oil, which is a by-product when producing ethylbenzene from benzene and ethylene, is subjected to a decomposition reaction in the presence of an acid catalyst, and then part or all of the decomposed product is supplied to a distillation system in the production of styrene from ethylbenzene. A method for decomposing and recovering ethylbenzene residue oil, which comprises recovering benzene, toluene, ethylbenzene and/or styrene.