JPS5916493B2 - Catalyst recovery method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to hydrogen fluoride-triboron trifluoride (hereinafter referred to as HF-BF3) during or after isomerization of hydrocarbons.
The present invention relates to a method for recovering and optionally reusing a catalyst.

It has been a long time since the use of tetraethyl lead, which has traditionally been used as an octane improver in gasoline, has been regulated, and large amounts of aromatic hydrocarbons or olefins have been added to compensate for the decrease in the octane number of gasoline due to lower lead. A large amount of catalytic cracking oil is added.

Aromatic hydrocarbons are important as raw materials for the chemical industry, and consuming large quantities of them as an energy source is not preferable from the standpoint of effective utilization of petroleum resources. In addition, the olefin content tends to form a gum, making it unsuitable for producing high-quality gasoline. Methyl-butyl ether (hereinafter M) is used as a gasoline additive to replace tetraethyl lead.
TBE) has been used.

While MTBE acts as an additive, it also acts as an energy source, and it is said that it can be added to gasoline in an amount of 5 to 15 wt%, which can substantially increase the production volume of gasoline and improve the aroma in gasoline. The content of group hydrocarbons can be reduced. However, MTB
Even when E was used, the addition of aromatic hydrocarbons could not be omitted. However, this aromatic hydrocarbon is expensive, and in order to further save on this expensive aromatic hydrocarbon, it is necessary to further increase the octane number of the gasoline base itself. It is known that the C5-C6 paraffins contained in the base material constituting gasoline generally have a degree of branching and have a small contribution to the octane number.

For this reason, a method of increasing the octane number by isomerizing the C5-C6 fraction to increase the branched Ti content has been carried out industrially. As an isomerization catalyst for C5-C6 paraffins,
Friedel-Crafts catalysts such as HF-BF3, hydrogen fluoride-15 ammonium fluoride, and solid acid catalysts such as platinum-alumina are known.

In the case of Friedel-Crafts catalysts, isomerization can be carried out at a low temperature of 10 to 60°C, which is equilibrium-favorable for the production of branched and wet hydrocarbons, but in the case of solid acid catalysts, isomerization is generally
A high temperature of 20 to 300°C is required, and the increase in octane number per oil pass is not very large. For example, Union Oil Products Co., Ltd.
In the Nex) method, the octane number (RON) of the platinum-alumina catalyst, which is used industrially as an isomerization catalyst for C5-C6 paraffins, is said to be about 82 after passing through the oil once. On the other hand, the present inventors have confirmed that the RON per oil passage when isomerizing using an HF-BF3 catalyst is 88 to 90. Hydrocarbon isomerization using HF-BF3 catalyst is originally carried out in a heterogeneous system, and usually
Any reactor used in a heterogeneous liquid-liquid reaction can be used, such as a complete mixing tank reactor, a mixer-settler reactor, and a tube reactor. .

For example, when using a completely mixed tank reactor, HF-
The raw material hydrocarbon is intermittently or continuously supplied to the reactor containing the BF3 catalyst, and after the catalyst and the hydrocarbon are brought into sufficient contact for a certain period of time, the reaction product liquid is collected inside the reactor or in a separate separation tank. It is separated into a catalyst layer and a hydrocarbon tank. This hydrocarbon layer is then heated to decompose it into product hydrocarbons and catalyst components, and the product hydrocarbons are removed. This catalyst component contains HF
-BF3 and small amounts of C1-C4 hydrocarbons. In addition, in the isomerization of hydrocarbons using an HF-BF3 catalyst, the activity of the catalyst gradually decreases due to aromatic hydrocarbons in the feedstock hydrocarbons or high-boiling products generated in small amounts during the reaction, so a part of the catalyst layer is It is necessary to extract and reproduce it intermittently or continuously. Under normal pressure, hydrogen fluoride is a liquid with a boiling point of 20°C, and boronic trifluoride is a liquid with a boiling point of -10°C.
Since the catalyst is a gas having a temperature of 0.3° C., separation of aromatic hydrocarbons or high boiling point hydrocarbons, which cause a decrease in activity, from the catalyst can be carried out very easily by distillation or the like. This extremely easy catalyst regeneration means that
This is one of the major advantages of using the HF-BFS medium. On the other hand, for example, when using a hydrogen fluoride-15-antimony fluoride catalyst, it is virtually impossible to regenerate a catalyst that has deteriorated due to heating or the like, and loss of the expensive catalyst cannot be avoided. The hydrocarbon layer obtained from the above-mentioned isomerization reaction product liquid contains 2 to 10 wt% of boron trifluoride accompanied or dissolved therein.

The content of boron trifluoride in the hydrocarbon layer varies depending on the reaction temperature and pressure. For example, when the reaction temperature is 50°C, the content of boron trifluoride at the reaction pressure of 10k9/CtAG is about 2wt%, 30k
9/CtliG is about 7wt%, 501cg/CtliG is about 1
It was found that it was 0 wt%. The boron trifluoride contained in the hydrocarbon layer is actually physically dissolved boron trifluoride and can be easily removed by heating. After compressing the hydrogen chloride to the reaction pressure in a compressor or liquefying it in a cooler,
Returned to the isomerization process.

The borosulfur trifluoride separated from the hydrocarbon layer usually contains hydrogen fluoride vapor and is extremely corrosive, making the use of compressors difficult due to their short lifespan and the need for high-grade materials. For this reason, it is economically disadvantageous, and this economic disadvantage increases when a large amount is handled. In addition, for recycling by liquefaction, the liquefaction temperature is, for example, 40 kg.
/CdG is as low as -30°C, so it cannot be said to be economically advantageous. The inventors discovered that the trifluoride dissolved in the hydrocarbon layer:
A method of recycling iodine to the isomerization process was studied, and the dissolved boron trifluoride was extracted and recovered with a liquid extractant containing at least hydrogen fluoride, and this extract was reused for the isomerization reaction if desired. Based on this new knowledge, we have arrived at the present invention. That is, the present invention is directed to hydrogen fluoride and boron trifluoride and hydrocarbons separated from the reaction product liquid obtained by isomerizing hydrocarbons in the presence of hydrogen fluoride and boron trifluoride. A hydrocarbon layer containing hydrogen fluoride is brought into contact with a liquid extraction agent containing at least hydrogen fluoride to extract boron trifluoride from the hydrocarbon layer to obtain an extract, and if desired, the extraction This is a catalyst recovery method characterized by reusing the liquid in the isomerization reaction.

The present invention is applicable to any reaction product liquid obtained during or after the reaction of hydrocarbon isomerization using HF-BF3, and is applicable to reaction product liquids obtained under any isomerization conditions. can do.

There are no particular restrictions on the isomerization reaction, but in practice, C5 to C6
It is suitably applied to reaction product liquids such as isomerization to increase branching of paraffins and isomerization of endo-tricyclo[5,2,1,02.6]decane to adamantane. As for the isomerization conditions, for example, the reaction temperature is usually 0 to 100°C, preferably 10 to 60°C.
However, a reaction pressure of 1 to 1001 Cg/CtltG, preferably 10 to 50 kg/DG is used. The reaction product liquid during or after isomerization is separated into a hydrocarbon layer and a catalyst layer by being allowed to stand at room temperature from the reaction temperature or at room temperature.

Usually, this standing time may be practically 30 minutes or less, preferably 30 seconds to 5 minutes. Alternatively, it may be actively placed in a gravitational field using, for example, a centrifuge. Further, heating or cooling is not particularly necessary at this time, but heating or cooling can also be performed. As mentioned above, this hydrocarbon layer contains a relatively large amount of hydrocarbons and a relatively small amount of hydrogen fluoride and boron trifluoride, and the catalyst layer also contains a relatively large amount of hydrogen fluoride and boron trifluoride. It contains boron trifluoride as well as relatively small amounts of hydrocarbons. By bringing this hydrocarbon layer into sufficient contact with a liquid extractant containing at least hydrogen fluoride, boron trifluoride contained in the hydrocarbon layer can be extracted at a high extraction rate.

In addition to hydrogen fluoride, the extraction agent may contain boron trifluoride, aromatic hydrocarbons, and/or high-boiling products. If the concentration of boron trifluoride in the tazoshi extraction agent increases, the extraction rate of boron trifluoride will decrease, so the lower the concentration, the better, but in practice it is preferably 5 wt% or less. Further, there is no problem in practical use as long as the concentration of aromatic hydrocarbons and/or high boiling point products in the extractant is usually 10 wt % or less. In addition, if the water concentration in the extractant is high, the corrosivity of the extract will increase, and... Since trifluoridation reduces the extraction rate of borage, it is preferably low, usually 5 wt% or less, preferably 1 wt%.
It is said that Boron trifluoride can be removed from the catalyst layer separated from the reaction product liquid, and the residue can be used as an extractant. Extraction temperature is -70 to 100℃, preferably -
A temperature of 20 to 20°C and an extraction pressure of 1 to 100 kg/CdG, preferably 10 to 50 k9/CdG are practically appropriate. The ratio of the weight of the extraction agent to the weight of the hydrocarbon layer is not particularly limited, but in practice it is usually 0.1 or more, preferably 0.
．． 1 to 3. The time required for extraction is usually 5 minutes or more, preferably 5 to 30 minutes. Note that the reaction pressure and the extraction pressure may be equal or different.

Extraction can be carried out either batchwise or continuously, and in the latter case, the flow of liquid in the extractor may be either countercurrent or cocurrent. Further, as the extractor, commonly used extractors such as a rotary perforated plate countercurrent extraction column, a tank type extractor, and a tube type mixer can be used. The extract thus obtained can be reused as is for the isomerization reaction, or it can be supplied to the isomerization reaction after concentrating the borosulfide trifluoride, for example by flash evaporation or distillation. It can also be reused.

A flow sheet of a process to which the present invention is applied is illustrated in FIG. That is, the raw material hydrocarbon and, if desired, a new catalyst (HF-BF3) are supplied to the isomerization reactor 2 from route 1, where the isomerization reaction proceeds.

The reaction product liquid extracted from the isomerization reactor 2 is sent to a separation tank 4 via a route 3, where it is separated into a hydrocarbon layer (upper layer) and a catalyst layer (lower layer). The hydrocarbon layer is sent to the bottom of the extraction column 7 via the pump 5 and the line 6 and rises within the extraction column 7. On the other hand, the catalyst layer is sent via route 8 to the isomerization reactor 2 and/or via route 9 to the separation column 10. In the separation column 10, the catalyst layer is separated into hydrogen fluoride accompanied by boron trifluoride and a mixture of hydrogen fluoride and high-boiling substances. The borosulfur trifluoride accompanied by a small amount of hydrogen fluoride becomes a gas and is sent from the top of the separation column 10 to the condenser 12 via the path 11, where the hydrogen fluoride is condensed into a liquid state and passed through the path. 13 and returned to the vicinity of the top of the separation column 10.
Further, in the condenser 12, boron trifluoride is not condensed and is returned to the isomerization reactor 2 through a path 14 in a gaseous state.
Note that the isomerization reactor 2, the separation tank 4, and the path 14 are connected to each other by a pressure equalization pipe 15.
The internal pressure of each of the separation columns 10 and 10 is maintained at a pressure T1 close to the isomerization reaction pressure. A mixture of hydrogen fluoride and high boilers is discharged from the bottom of the separation column 10, and this mixture is sent to a hydrogen fluoride distillation column 17 via a path 16. This mixture is separated into high-boiling substances and hydrogen fluoride in a hydrogen fluoride distillation column 17. The high-boiling substances are taken out from the bottom of the column through a path 18, and the hydrogen fluoride is sent in gaseous form to a cooler 20 through a path 19. This liquid hydrogen fluoride is sent to the vicinity of the top of the extraction tower 7 via a pump 21 and a path 22, and descends inside the extraction tower 7 as an extractant. The raffinate is discharged from the top of the extraction column 7. This raffinate is sent to the next step, such as distillation, through a path 23. On the other hand, an extract is extracted from the bottom of the extraction tower 7 and Tl. ．． This extract passes through a pump 24 and a route 25, and then a route 26 branched from the route 25.
It is combined with the catalyst layer from route 9 and fed to separation column 10 and/or sent to isomerization reactor 2 through route 27 and route 8 branched from route 25. Note that the internal pressure of the hydrogen fluoride distillation column is lower than the isomerization reaction pressure, and the internal pressure of the extraction column is slightly higher than the isomerization reaction pressure.

In this way, in the present invention, the extraction rate of hydrogen trifluoride from the hydrocarbon layer depends on the concentration of boron trifluoride in the extractant, the extraction temperature and pressure, and the weight ratio of the extractant to the hydrocarbon layer. Although it varies depending on the situation, it is usually 60% or more.

According to the present invention, boron trifluoride contained in a hydrocarbon layer from a hydrocarbon isomerization reaction product liquid can be recovered very efficiently and easily.

Furthermore, when the recovered boron trifluoride is reused in the isomerization reaction, it is possible to omit a compressor or liquefaction device or to save power for compression or liquefaction. Next, the present invention will be explained in more detail with reference to Examples.

Example 1 45 parts by weight of n-pentane, 45 parts by weight of n-hexane, 10 parts by weight of cyclohexane, 0.1 parts by weight of 2,2
, 4-trimethylpentane isomerization raw material 2147
was isomerized using 330r hydrogen fluoride and 189y boron trifluoride at a reaction temperature of 50°C and a pressure of 30kg/CrAG, and the resulting reaction product liquid was allowed to stand at 50°C for 3 minutes. A hydrocarbon layer containing .57% by weight of hydrogen fluoride and 6.85% by weight of boron trifluoride was obtained.

This hydrocarbon layer 627 and liquid hydrogen fluoride 132y containing 2 wt% boron trifluoride were heated at 50°C and under a pressure of 30 kg.
/CdG for 10 minutes with stirring. The concentration of boron trifluoride in the hydrocarbon layer after extraction had decreased to 1.32% by weight. Example 2 An isomerization reaction was carried out in the same manner as in Example 1 using raw materials having the same composition as in Example 1, changing the pressure and temperature, and the resulting reaction product liquid was allowed to stand at the reaction temperature for 3 minutes. A hydrocarbon layer was obtained.

This hydrocarbon layer and liquid hydrogen fluoride were stirred and mixed for 10 minutes to extract. The concentration of boron trifluoride in the hydrocarbon layer after extraction was as shown in Table 1. Further, reaction conditions, extraction conditions, etc. are shown in Table 1. Example 3 1.4wt% borosulfide and 2.1wt as extractants
The same procedure as in Experiment 1 of Example 2 was carried out except that liquid hydrogen fluoride containing % m-xylene was used, and the concentration of borofluoride trifluoride in the hydrocarbon layer after extraction was 2.4 wt. It was in %.

Example 4 An isomerization reaction product liquid obtained by performing isomerization under the same conditions as in Example 1 was allowed to stand at 50° C. for 3 minutes to obtain a hydrocarbon layer.

This hydrocarbon layer was continuously supplied from the lower part of a rotary perforated plate extraction column with 5 plates, and liquid hydrogen fluoride containing 0.2 wt% boron trifluoride was continuously supplied from the upper part of the column. . The residence time of hydrocarbons was 17.8 minutes, the extraction temperature was 0° C., the hydrogen fluoride/hydrocarbon supplied to the column (weight ratio) was 0.2, and the extraction pressure was 40k9/CdG. Hydrocarbon layer after extraction (
The concentration of boron trifluoride in the raffinate solution was 6.85 wt% to 0.
．． It decreased to 9wt%. Note that this extraction tower is made of SUS3L
6L made saw 30~20℃, 10~501Cg/Cd
Various extraction experiments were conducted for a total of 342 hours in the range of G, and the average corrosion rate was as low as 0.13 mm/year.Example 5 Hydrogen 330y1 Boron trifluoride 1907 and 0.1w
N-pentane 2107 containing t% of 2,2,4-trimethylpentane was charged, and the reaction temperature was 50°C and the pressure was about 30°C.
k97/Cr! The isomerization reaction was carried out using IG for 65 minutes.

After the reaction was completed, the mixture was allowed to stand at 50° C. for 3 minutes, and a small amount of the separated hydrocarbon layer was sampled for compositional analysis. The isomerization rate of i-pentane from n-pentane was 83.6%, and the content of boron trifluoride was about 67% by weight. Boron trifluoride contained in the hydrocarbon layer was extracted under the same conditions as in Example 4, and this extract was combined with the extract obtained in Example 4.

The BF3 concentration in this mixed extract was 23.4 wt%. Transfer the entire amount of the extract to an autoclave with an internal volume of 200 m1 equipped with a reflux condenser, and reduce the internal pressure of the autoclave to 351C.
The mixture was gradually heated to 147° C. while maintaining the temperature at 9//CF71G. Boron trifluoride generated by heating was extracted from the upper part of the reflux condenser (0°C) and supplied to the above-mentioned isomerization reactor (50°C, containing the catalyst layer used for the isomerization reaction). When the pressure in the isomerization reactor reaches 30k9/CrAG, the supply of boron trifluoride is stopped and n-
Pentane (0.1w1%f containing 2,2,4-trimethylpentane) was pumped into 2107 at 50°C.
The isomerization reaction was carried out at 30 kg/CrAG. The isomerization rate of n-pentane after 65 minutes of reaction was 83.0%, and no decrease in the isomerization rate was observed due to the use of recovered BF3.

Example 6 17.

6 wt% endo-tricyclo [5.2.1.02.6
] Isomerization raw material 18607 consisting of decane and 82.4 wt% n-pentane was used as a catalyst with hydrogen fluoride of 11407 and boron trifluoride of 2457 at a reaction temperature of 100%.
After isomerizing for 10 minutes at ℃ and pressure 34kVF71G, this reaction product solution was allowed to stand still for 10 minutes, resulting in a concentration of 1.11wt%.
A hydrocarbon layer and catalyst layer containing 3.37 wt % of boron trifluoride and 3.37 wt % of boron trifluoride were obtained.

Using this hydrocarbon layer, extracting liquid hydrogen fluoride that does not contain boron trifluoride at an extraction temperature of 0°C and an extraction pressure of 20°C.
kVcdG. Extraction was carried out for 10 minutes under conditions of extractant/hydrocarbon (weight ratio) of 1.

Boron trifluoride contained in the hydrocarbon layer after extraction is 0.0
It was 6 wt%.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet of a process to which the present invention is applied. 2...isomerization reactor, 4...separation tank,
5...Pump, 7...Extraction tower, 10.
... Separation column, 12 ... Condenser, 15 ...
... Pressure equalization tube, 17 ... Hydrogen fluoride distillation column. 20...Cooler, 21...Pump, 2
4...Pump.

Claims (1)

[Claims] 1 A hydrocarbon layer containing hydrogen fluoride and boron trifluoride and hydrocarbons separated from a reaction product liquid obtained by isomerizing hydrocarbons in the presence of hydrogen fluoride and boron trifluoride, and a small amount of Contact with a liquid extraction agent containing hydrogen fluoride to extract boron trifluoride from the hydrocarbon layer to obtain an extract, and if desired, reuse the extract for the isomerization reaction. A method for recovering a catalyst, characterized by: