JPS6023091B2 - Process for treating by-products during the production of isopropyl alcohol by direct hydration of propylene - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to economically recover by-products generated in the in-propyl alcohol production process by direct hydration of propylene for the purpose of effective utilization, and to recover water contained in the created product. This relates to treatment and separation to the extent that it passes wastewater standards.

During the production of inpropyl alcohol by the direct hydration method, various created organisms are generated.

They are broadly classified into water-soluble by-products and aquatic port creation products, and the representative ones are as follows. Water-soluble by-product normalf.

Hydrocarbons mainly composed of propyl alcohol, C6 alcohols, isopropyl ether, propylene dimers and trimers,
Incidentally, inpropyl alcohol, which is separated along with these created substances, can also be considered as a component of water-soluble by-products in the manufacturing process.

Collecting these organisms individually would increase equipment construction costs and operating costs, so they are separated and collected as a mixture in the form of a foundry fraction from each stage of the inpropyl alcohol manufacturing process. It is usually separated and collected while containing a large amount of water.

The location and composition of these created substances will be explained according to an example of the process for producing inpropyl alcohol by direct hydration of propylene shown in FIG.

Propylene is supplied through conduit 1, and unreacted recovered propylene is supplied through conduit 2 to propylene purification tower A. Light trade components (off gas) are separated from the top of the tower through conduit 3, and from the bottom of the tower through conduit 4.
Separate military quality by-products.

Purified propylene is extracted from the upper stage of the column A through a conduit 5, purified water is added through a conduit 6, a catalyst such as phosphoric acid is added through a conduit 7, and the mixture is supplied to the top of the reaction column B.
The reaction product is extracted from the bottom of column B through conduit 8, and after separating and recovering unreacted propylene, it is supplied to the middle stage of extractive distillation column C. By spraying pure water as an extractant through conduit 9, water-soluble substances fall to the bottom of the roll and are extracted from conduit 1 in a hydrated state. On the other hand, the created product fraction, which mainly consists of by-products from the scales and water, is extracted from the column via conduit 11. The resulting inpropyl alcohol is extracted and supplied to the purification process. On the other hand, water is extracted from the bottom of the column through conduit 15, and created crab material is extracted from the top and middle stage of the column through conduits 13 and 14. The vertical gas component from the conduit 3 of the created material in the above process can be directly used as fuel as off-gas.

The by-products in conduit 4 are hydrocarbons mainly composed of propylene dimers and trimers as water-soluble by-products, isopropyl ether, and isof as water-soluble by-products.

. Contains pill alcohol and a small amount of water. The by-product fraction in the conduit 11 contains hydrocarbons mainly consisting of propylene dimers and trimers, isopropyl ether,
Impropyl alcohol and C6 as water-dropping by-products
Contains alcohol. The by-product crab material in conduit 13 contains isopropyl ether as a water-dropping by-product, acetone, impropyl alcohol, and a small amount of water as water-soluble products.

The by-product fraction in conduit 14 contains the water-soluble derivatives normal propyl alcohol, small amounts of inpropyl alcohol and C6 alcohols, and a large amount of water.

Note that the location and composition of the created organisms will vary depending on the type of inpropyl alcohol production method and operating conditions, etc.
There is no big difference in the ingredients.

Separating and recovering by-products as a mixture in this way causes various problems in subsequent treatment and utilization.

When trying to effectively utilize by-products, for example, as fuel, the by-product fractions in conduits 4, 11, and 13 in FIG. 1 have low moisture content, so there is no particular problem; Since the derived product fraction has a water content of 40 to 9% by weight, its calorific value is extremely low, and it cannot be used alone as a fuel.

Also, when the by-product fraction in the conduit 14 is mixed with other by-product fractions or other fuel oil and stored in a fuel oil mixing tank for use as fuel, water will separate and accumulate at the bottom of the tank; Because it contains a large amount of alcohol, it cannot be drained as is. Even if a distillation operation is carried out to reduce the water content of a mixture such as the created crab fraction in conduit 14, this fraction is a water-alcohol composition, so co-nutrients occur during distillation, and it does not dissolve at room temperature and pressure. Its composition is 72% normal propyl alcohol and 28% water.
Therefore, the water content cannot be reduced to less than 28% by simple distillation.

In order to further reduce the water content to below the azeotropic composition, after concentrating to the azeotropic composition, an azeotropic agent (for example, benzene) is added and water is removed by three-component azeotropic distillation, and if necessary, inpropyl alcohol , C6 alcohol is separated by distillation.

However, this method requires a large amount of construction and operating costs, making it uneconomical as a method for treating created organisms. The present invention
Provided is a method for recovering by-products during the production of inpropyl alcohol by a direct hydration method at a low water content and separating water from the by-products that can pass any wastewater standards,
This is an attempt to solve the problems mentioned above.

The present inventors completed the present invention by paying attention to the fact that the chick water-soluble by-product has the property of dissolving water-soluble by-products. That is, the present invention mixes water-containing water-soluble by-products and elutriated water-soluble by-products created during the production of inpropyl alcohol by direct hydration of propylene, and then separates them into an oil phase and an aqueous phase due to the difference in specific gravity. The aqueous phase is subjected to distillation, the top fraction is sent to the mixing step, and the water is separated from the bottom. This is a processing method.

The method for producing in-propyl alcohol using the direct hydration method of propylene in the present invention is not particularly limited, and any of various production methods can be applied.

As a known production method, from propylene and water or steam, in a liquid phase or gas phase, in the presence of a catalyst such as phosphoric acid, a tungstic acid compound, a strongly acidic cation exchange resin, etc.
There is a method for producing inpropyl alcohol in a one-step reaction.

The by-products treated in the present invention are water-soluble by-products and water-soluble by-products as described above.

When inpropyl alcohol is separated along with other by-products during the manufacturing process, it is included in the water-soluble derived product in the present invention. These by-products are separated as a mixture with various components and composition ratios from various positions in the inpropyl alcohol production process as described above, but depending on the type of Z production technology and operating conditions, these positions, components, Composition ratios can of course vary. The water-containing water bathing organisms and scale water-soluble by-products to be mixed can be by-products, which are usually mixtures of various compositional proportions, and the water-containing bathing organisms and scale water-soluble by-products may be mixed with each other. It may be separated from the manufacturing process as a mixture.

That is, the water-soluble foam is in a water-containing state, but even a mixture containing other water-soluble by-products can be effectively used as a raw material for the treatment of the present invention.On the other hand, the water-soluble foam is , other water-emitting organisms, and mixtures containing water can also be effectively used as raw materials for the treatment of the present invention. below,
The method of the present invention will be explained in more detail with reference to the drawings, but the present invention is not limited thereto.

The water-containing water-soluble by-product and the chick water-soluble by-product may be mixed in any suitable manner, but for example, as shown in FIG.
The by-product crab fraction from the conduit 4 is carried out by the conduit 4, the by-product crab fraction from the conduit 11 is carried out by the conduit 17, the by-product crab fraction from the conduit 13 is carried out by the conduit 18, and the created product fraction from the conduit 14 is carried out by the conduit 19. This can be carried out by supplying each to the mixing tank E.

The method of mixing each created substance in the present invention can be by an in-pipe mixing method without using a mixing tank, or, for example, a second
It is also possible to use both the mixing tank method and the in-pipe mixing method, such as supplying the creation material through the conduit 26 shown in the figure. The aqueous phase separated in the separation process based on the difference in specific gravity, which will be described later, is subjected to distillation to extract the created organisms from the top of the column, and the resulting product is mixed with the created organisms mixture, at which time it is supplied to the mixing tank E. The mixture may be mixed or in-line mixed into the by-product mixture stream in conduit 21 by conduit 24 as shown in FIG.

It is preferable to mix these by-products in a liquid state, and the temperature and pressure of each conduit and mixing tank can be set to appropriate conditions, but usually normal temperature and pressure may be used.

Separation of water-soluble by-products from water is achieved by the dissolution of water-soluble by-products into water-soluble debris, so the mixing ratio of water-soluble debris and water-soluble by-products is , can be changed as appropriate depending on the required value of water content in the oil phase separated in the step of separation based on the specific gravity difference described later. Ta
In other words, as the proportion of water-degrading organisms increases, the water content in the oil phase tends to increase.

This relationship is shown in Figure 3. As shown in Figure 1, water-repellent formations and water-repellent by-products in the by-products produced during the production of inpropyl alcohol by direct hydration of propylene are usually reduced to a water content of 5% by weight or less in the oil phase. Therefore, there is no problem of water separation during tank storage as in the conventional case.

However, if it is desired to further reduce the water content in the oil phase depending on the application, it may be necessary to reduce the water content depending on factors such as operating conditions.
In cases where the amount of water-borne products increases relatively and it is not desired to increase the water content in the oil phase, appropriate measures may be taken in addition to adjusting the mixing ratio of by-products. Provision may be made to add other compounds, for example via conduit 20. Other compounds that can be added for this purpose are not particularly limited as long as they are compounds that dissolve elutriforms and are water-soluble. The compound is not limited to the same compound as the created organism, but can be appropriately selected from aliphatic hydrocarbon compounds, aromatic hydrocarbon compounds, alicyclic hydrocarbon compounds, ethers, and the like. When there are various manufacturing processes, such as in a petrochemical factory, it can be used as a compound to add generated products separated from these processes, such as non-aromatic hydrocarbons obtained from the aromatic extraction process. This contributes to the collection and utilization of byproducts throughout the factory. The aqueous by-product mixture obtained by the above-described mixing step typically contains about 20% to 70% water.

This mixture is then separated into an oil phase and an aqueous phase based on the difference in specific gravity.

The separation device can be appropriately selected and used as long as it has the ability to separate based on the difference in specific gravity, but preferably a decanter or a settler can be used.
It is more preferable to use a decanter since continuous separation is possible. Further, when using a settler, the time required for separation is 3 to 30 minutes, usually within 1 minute. Also,
The temperature and pressure of the separation device can be set as appropriate, but usually normal temperature and pressure may be used. FIG. 2 shows an example using a decanter.

The creation mixture stream is supplied to the decanter F via a conduit 21, the oil phase is removed via a conduit 22, and the aqueous phase is removed via a conduit 23. The water content in the oil phase can be as low as 5% by weight or less, so even if it is stored in a tank, water will not separate at the bottom, and the calorific value will be about 85%.
Since it has a high value of 00 kcal/k9, it can be used as a fuel as it is, and it is also a light fuel, does not contain sulfur, and does not generate sulfur oxides when burned, so it can be a high-quality fuel for pollution prevention.

It can also be used effectively for purposes other than fuel. On the other hand, the aqueous phase contains 10 to 20% by-products, and the COD value of the aqueous phase is approximately 5×
Since it is impossible to drain it out of the system as it is, it is then subjected to distillation, and the created organisms in the aqueous phase are extracted from the water phase, and the overgrown fraction is used as the water phase. While mixing with the mixture, water is separated from the bottom of the column, which contains almost no by-products and has a very low COD value.

The distillation column may be of any type, but a type commonly referred to as a stripper is preferred.

The operating conditions of the distillation column are such that by-products in the aqueous phase are extracted from the top of the column*, and water that contains almost no created products and has a COD value that meets any wastewater standards can be separated from the bottom of the column. , set the temperature and pressure. In Fig. 2, the aqueous phase is supplied to the distillation column G through a conduit 23, and from the top of the column, concentrated by-product crab fraction containing approximately 30 to 40% water is separated through a conduit 24. After cooling, it is mixed with the by-product mixture stream and returned to the separator F, where the created product and water are separated.

On the other hand, water containing almost no by-products is separated from the bottom of the column through a conduit 25. The COD value of this water can be set to 3 or less, and it passes any drainage standards within the current regulations, so it can be discharged as is.

It is also possible to reuse this water as water for propylene hydration. Example 1 According to the manufacturing process shown in Figure 1, using a phosphoric acid catalyst and using 0.2 mol of water per 1 mol of propylene as a raw material, a pressure of 4.
In the method for obtaining inpropyl alcohol by direct hydration of propylene at 0k9/m, conduits 4, 11, 13
and 14 were treated in the steps shown in FIG.

Mixing and separation are carried out at normal temperature and pressure, and distillation is carried out at a top temperature of 8.
800, the bottom temperature was 1020, and the pressure was 1.06 k9/m.

The flow rate, components and composition ratios of each conduit are shown in Table 1.

As can be seen from Table 1, almost all the by-products were recovered in the oil phase and the water content was 4% by weight, with no water separation observed after 4 hours in the storage tank. On the other hand, the water from the bottom of the distillation column contains less than one byproduct and C
The OD value was 1 leg, which passed any drainage standards under the current law.

Table 1 Example 2 2 parts by weight of the non-aromatic compound stream (components are primarily C6-C8 non-aromatic hydrocarbon compounds) separated from the aromatic solvent extraction step was added through conduit 201 in FIG. Others are
It was operated in the same manner as in Example 1.

The results * are shown in Table 2. Water content in the oil phase is 2% by weight
The same results as in Example 1 were obtained, except that the Table 2

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of an in-propyl alcohol manufacturing process by direct hydration of propylene. FIG. 2 is a diagram showing an example of an implementation process of the present invention. Third
The figure is a diagram showing an example of the relationship between the water content in the oil phase and the water-soluble by-product content in the oil phase according to the present invention. A...
...Propylene purification tower, B...Reaction tower, C...
...Extractive distillation column, D...Inpropyl alcohol concentration column, E...Mixing tank, F...
Separation device, G... Distillation column, Day... Heat exchanger. 1st prisoner 2 illustrations 3 crabs

Claims (1)

[Claims] 1. Water-containing water-soluble by-products and poorly water-soluble by-products, which are by-products during the production of isopropyl alcohol by direct hydration of propylene, are mixed, and then separated into an oil phase and an aqueous phase by the difference in specific gravity, and the aqueous phase is separated into an oil phase and an aqueous phase. 1. A method for treating by-products during the production of isopropyl alcohol by direct hydration of propylene, characterized by subjecting it to distillation, returning the top fraction to the mixing step, and separating water from the bottom of the column.