JP2715525B2 - Dehydrohalogenation method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for dehydrohalogenating halogenated saturated hydrocarbons having 2 to 6 carbon atoms (hereinafter abbreviated as C2 to C6). More specifically, the present invention relates to a method for dehydrohalogenating a halogenated saturated hydrocarbon by contacting a catalyst comprising zeolite, which is a kind of crystalline aluminosilicate, with a C2 to C6 halogenated saturated hydrocarbon. is there.

[Prior Art] The dehydrohalogenation reaction of halogenated saturated hydrocarbons, particularly the dehydrochlorination reaction of chlorinated saturated hydrocarbons, is an industrially important reaction, and several types of industrial processes are employed. Among them, as a typical example, vinyl chloride monomer (hereinafter abbreviated as VCM) is widely produced by dehydrochlorination by thermal decomposition of 1,2-dichloroethane (hereinafter abbreviated as EDC). In this case, the dehydrochlorination reaction is usually performed at a temperature of 500 ° or more and a pressure of about 50 kg / cm ² G.

However, this method has a relatively low conversion rate of EDC, so that the steps of recovering unreacted substances and separating the products are complicated, and require high temperature conditions and thus require much energy. Has disadvantages. Therefore, there is a strong demand in the art for the development of an economical dehydrohalogenation method as an alternative to the conventional method.

Various zeolite catalysts have been proposed in the method for dehydrohalogenation of halogenated saturated hydrocarbons. For example, a method using ZSM-5, silicalite or the like as a catalyst (JP-A-58-167526) or a method using a catalyst obtained by treating or reacting a Y-type zeolite with a Lewis acid (JP-A-54-79209) ), A method using a catalyst in which a rare earth metal chloride is deposited on a zeolite (JP-A-61-30), a method using an offretite-erionioio zeolite (hereinafter abbreviated as an OE zeolite), or a method using an L-type zeolite as a catalyst ( JP-A-60-252433).

In these citations, the dehydrohalogenation of halogenated saturated hydrocarbons, such as the dehydrochlorination of EDC,
It has been shown that the reaction can be carried out at lower reaction temperatures as compared to the pyrolytic dehydrochlorination reaction. However, these references do not mention the life of the catalyst.

[Problems to be Solved by the Invention] It is clear that a zeolite catalyst works effectively in a method for dehydrohalogenation of a halogenated saturated hydrocarbon, but from an industrial point of view, the catalyst life is as long as the activity of the catalyst along with the activity of the catalyst. This is a very important issue.

It is well known that, when zeolite is generally used as a catalyst and various hydrocarbons are reacted, a decrease in catalytic activity over time due to the deposition of carbonaceous material on the zeolite catalyst is observed. Therefore, even in a dehydrohalogenation reaction of a halogenated saturated hydrocarbon using a zeolite catalyst, it is easily presumed that the activity is reduced due to carbon deposition on the catalyst. In fact, the present inventors conducted a dehydrohalogenation reaction using an OE zeolite exhibiting the highest catalytic performance among the above cited references. Was. It is possible to recover the activity of a catalyst whose activity has decreased due to carbon deposition by treating it at a high temperature under air flow, but the regeneration process is a complicated operation, and from an industrial point of view, carbon deposition should be minimized. A catalyst with a small activity and a small deterioration with time is desired.

[Means for Solving the Problems] In view of such circumstances, the present inventors have conducted intensive studies on a dehydrohalogenation method. As a result, a catalyst obtained by mixing a salt containing a specific metal cation with an OE-based zeolite was obtained. By using this, it is possible to maintain the high activity and selectivity of the 0E-based zeolite catalyst with respect to the dehydrohalogenation reaction of halogenated saturated hydrocarbons, particularly the dehydrochlorination reaction of chlorinated saturated hydrocarbons, while maintaining the activity over time. It has been found that the decrease of the catalyst is remarkably small and the life of the catalyst is prolonged, and the present invention has been completed. That is, the present invention relates to an OE zeolite in which exchangeable cations are one or more metal cations selected from the group consisting of alkali metals, and a salt containing one or more metal cations selected from the group consisting of alkali metals. The present invention provides a method for dehalogenating halogenated saturated hydrocarbons, which comprises contacting a mixed catalyst with a C2 to C6 halogenated saturated hydrocarbon.

 Hereinafter, the present invention will be described in detail.

In the method of the present invention, a specific zeolite is used as a catalyst, and the zeolite is usually called a crystalline aluminosilicate. Zeolites are composed of a SiO ₄ tetrahedron and an AlO ₄ tetrahedron, and the types are different depending on the bonding mode of each tetrahedron, and many types are known.

The zeolite used as a catalyst in the method of the present invention is an OE zeolite.

Examples of OE zeolites include offretite, tetramethylammonium-offretite, erionite, and zeolites having a mixture of offretite structure and erionite structure, such as zeolite OE (see JP-A-59-69420). , ZSM-34 zeolite and the like.

An OE zeolite has a powder X-ray diffraction pattern characteristic of its structure, and can be distinguished from other zeolites by its pattern. Table 1 shows an X-ray powder diffraction pattern of an OE zeolite used as a catalyst in the present invention by a copper Kα double line. The OE zeolite generally has the following composition expressed in terms of the molar ratio of oxides.

_{M 2 / n O · Al 2} O 3 · (5~10) SiO 2 (M is a cation of valence n.) Although some OE-based zeolites are naturally dependent, they can be synthesized, and the OE-based zeolites used in the method of the present invention have few impurities and are preferably synthetic zeolites with high crystallinity. is there.

Methods for synthesizing OE-based zeolites are known. For example, as an example of a method of synthesizing tetramethylammonium-offretite, a method disclosed in JP-A-58-135123 can be mentioned, and as an example of a method of synthesizing erionite,
The method disclosed in Japanese Patent Publication No. 50-23400 can be mentioned. As an example of a method for synthesizing an OE zeolite having a mixture of an offretite structure and an erionite structure, Japanese Patent Application Laid-Open No.
Japanese Patent Publication No. 36-12569 discloses a method disclosed in Japanese Patent Publication No. 420-125, as an example of a method for synthesizing zeolite T. Each of the methods disclosed in Japanese Patent No. 58499 can be mentioned.

That is, this is a method in which a silica source, an alumina source, an alkali source, a potassium source and water are used as raw materials, the oxide molar ratio is appropriately determined, and heating crystallization is performed.

As-synthesized zeolite usually contains cations such as Na ions as metal cations. It is known that metal cations contained in zeolite can be easily exchanged for other cations by ion exchange treatment.

In the method of the present invention, the exchangeable cation is an alkali metal cation, and the alkali metal cation is L.
i, Na, K, Rb and Cs can be mentioned, and among them, K, Rb and Cs are preferable.

The alkali metal cation can be easily introduced into zeolite by a known ion exchange treatment. For example,
Using an inorganic hydrochloric acid such as a chloride soluble in water of an alkali metal cation or a nitrate, or an organic acid salt such as an acetate or an oxalate, an aqueous solution of 0.01 to 5 mol / l is prepared, and zeolite is added to the aqueous solution. The ion exchange treatment may be performed at a temperature of 20 to 100 ° C. for 0.5 to 24 hours. Usually, after the ion exchange treatment, the slurry is filtered, and the obtained solid is dried at 80 to 150 ° C for 1 to 24 hours. The above operation may be repeated several times.

The ion exchange may be performed by another method, for example, a method of circulating and contacting the aqueous solution containing the metal cation with the fixed bed made of the zeolite. When the synthesized zeolite contains an organic cation such as tetramethylammonium, the organic cation is preferably removed in advance to increase the ion exchange rate of the exchanged alkali metal cation. For this purpose, preliminary firing may be performed as a pretreatment of the ion exchange treatment, and this preliminary firing treatment may be performed at a temperature of 400 to 700 ° C. for 1 to 10 hours under an air flow.

The method of the present invention is characterized in that a mixture of an OE zeolite whose exchangeable cation is an alkali metal cation and a salt containing an alkali metal cation is used as a catalyst.

The method of mixing such a salt with the zeolite is not particularly limited, but the powder of the zeolite and the salt or a slurry, an aqueous solution or the like is appropriately combined and mixed, or as described in detail later, with the zeolite. An aqueous solution of the salt is mixed, water is removed by, for example, heating and evaporating, and a supporting method of supporting the salt on zeolite is used.

Examples of the alkali salt cation of the salt containing an alkali metal cation include Li, Na, K, Rb and Cs.
b and Cs are preferable, and among them, Rb and Cs are preferable. There is no particular limitation on the anion of the salt containing the alkali metal cation, and the anion may be changed during the pretreatment, the reaction, or the calcination.

The loading of the salt containing the alkali metal cation on the zeolite can be easily carried out by using a known loading method. The supporting method is not particularly limited. For example, using an inorganic acid salt such as chloride or nitrate soluble in water of metal cation, or an organic acid salt such as acetate or oxalate, the aqueous solution of the salt is converted into the zeolite. Impregnated, then 80 ~
It can be carried out by drying at 150 ° C. and removing water.

The mixing (supporting) of the salt with the zeolite may be performed on the zeolite powder, or may be performed on the molded zeolite catalyst.

The salt can be mixed (supported) in the range of 0.1 to 40% by weight, preferably 1 to 20% by weight based on the zeolite. If the mixing (supporting) is less than 0.1% by weight, the effect of the mixing (supporting) will not be sufficiently exhibited, and if it exceeds 40% by weight, the activity of the catalyst will decrease.

In the method of the present invention, the shape of the catalyst is not particularly limited,
A molded product may be used, but powder may be used as it is. The molding method may be an ordinary method, for example, a compression molding method, an extrusion molding method, a spray drying granulation method, or the like. In the case of molding, a substance inert to the reaction may be added as a binder or a molding aid for the purpose of increasing the mechanical strength. For example, silica, alumina, silica-alumina, clays, graphite, stearic acid, starch, polyvinyl alcohol, etc. can be added in the range of 0 to 80% by weight, preferably 2 to 30% by weight.

The catalyst obtained as described above is used after being calcined. The baking treatment may be performed at 400 to 700 ° C. for 1 to 10 hours under air flow.

In the method of the present invention, the dehydrohalogenation reaction of a halogenated saturated hydrocarbon can be carried out in a gas phase or a liquid phase, but a gas phase is preferred. In this case, a conventionally known reaction method such as a fixed bed flow system or a fluidized bed system can be employed.

In the method of the present invention, the C2 to C6 halogenated saturated hydrocarbon as a raw material may be a C2 to C6 saturated hydrocarbon containing at least one hydrogen atom and one halogen atom.
Examples thereof include C6 chlorinated saturated hydrocarbons, brominated saturated hydrocarbons, and iodinated saturated hydrocarbons, and C2 to C3 chlorinated saturated hydrocarbons are preferred.

The reaction conditions vary depending on the reaction system and the like, and it is difficult to uniformly define them. However, the reaction temperature is usually preferably in the range of 150 to 400 ° C, and particularly preferably in the range of 200 to 350 ° C. Reaction temperature
If the temperature is lower than 150 ° C., a sufficient reaction rate cannot be obtained. If the temperature exceeds 400 ° C., energy consumption increases, which is not only economically disadvantageous but also causes a side reaction such as a polymerization reaction of a product to proceed.

The reaction pressure is not particularly limited, and the reaction can be carried out under normal pressure, reduced pressure or increased pressure. The dehydrohalogenation reaction can be carried out by using a halogenated saturated hydrocarbon alone or in an inert atmosphere. To obtain an inert atmosphere, the raw material may be diluted with nitrogen, helium, or the like. In this case, the source concentration is not particularly limited, but is preferably 1 to 99%.

In the method of the present invention, the contact time is, in the case of a fixed bed flow reaction system, 10 to 10 as a gas space velocity (GHSV).
000 hr ^-1 is good, and 50 to 5000 hr ^-1 is preferable. The product can be separated and purified from the production system by a conventional method, and the unreacted halogenated saturated hydrocarbon can be recovered and recycled.

[Effects of the Invention] According to the method of the present invention, the catalyst used has a high dehydrohalogenation activity, and the raw material conversion rate is high, so that the raw material and the product can be easily separated. In addition, the decrease in catalyst activity due to the deposition of carbonaceous material on the catalyst is extremely small, and the catalyst life is long, so that long-term continuous operation is possible. Therefore, the method of the present invention is industrially extremely significant as compared with the conventional method.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to only these examples.

In addition, the salt mixing (supporting) amount shown in the examples represents a numerical value calculated by the following equation.

The conversion and the selectivity represent numerical values calculated by the following equations, respectively.

In addition, the carbonaceous deposition amount indicates a numerical value calculated by the following formula when the weight loss due to carbonaceous combustion at 300 to 600 ° C. when the catalyst after the reaction is continued for a specified time is subjected to thermogravimetric analysis.

Example 1 An OE zeolite and zeolite OE were synthesized based on the method described in JP-A-59-69420. That solid sodium hydroxide in pure water 701.2g (NaOH: 93wt%) 23.6 %, solid potassium hydroxide (KOH: 85wt%) 26.8g, aluminate Soar solution _{(Na 2 O: 19.2wt%,} Al 2 O 3: 20.66 wt%) 51.4 g was added to make a uniform solution, and then, with good stirring, amorphous solid silica (white carbon manufactured by Nippon Silica Kogyo Co., Ltd.)
9 g was added, and a reaction mixture having the following composition was obtained in the molar ratio of the oxide.

3.9Na ₂ O · 1.83K ₂ O · Al ₂ O ₃ · 18.8SiO ₂ · 382H ₂ O This was charged into an autoclave and heated at 150 ° C. for 40 hours while stirring at 250 rpm. The obtained slurry was subjected to solid-liquid separation, sufficiently washed with water, and dried at 150 ° C. for 5 hours to obtain a powder having the following composition.

0.21Na powder X-ray diffraction pattern of the _{2 O · 0.76K 2 O · Al} 2 O 3 · 7.4SiO 2 this one as shown in Table 2, was zeolite OE. In addition, powder X-ray diffraction was measured using the Kα double line of copper.

This zeolite OE was subjected to a Cs ion exchange treatment. 20 g of zeolite OE was added to 500 g of a cesium chloride aqueous solution (1.3 mol / l), and ion-exchanged at 90 ° C. for 5 hours. Thereafter, the slurry was filtered, and the obtained solid was thoroughly washed with water, and then washed with water.
Dry at 16 ° C. for 16 hours. This Cs ion exchange zeolite OE
The composition (hereinafter referred to as Cs-O / E), were _{0.26K 2 O · 0.77Cs 2 O ·} Al 2 O 3 · 7.4SiO 2. This Cs-O / E was subjected to a cesium chloride supporting treatment. To 15 g of Cs-O / E, silica gel (SiO ₂ : 30 wt%) was added as a binder so as to be 20 wt%, an appropriate amount of water was added, and 0.18 g of cesium chloride was added thereto (salt). The mixture was evaporated to dryness with stirring, pulverized, pulverized with graphite to 5 wt%, and compression-molded into 5 mmφ × 2 mmL. This catalyst was calcined at 540 ° C. for 3 hours under flowing air.

Using this catalyst, a dehydrochlorination reaction of HDC was carried out.
10g of catalyst into Pyrex reaction tube (20mmφ × 500mmL)
And the catalyst was supplied with a raw material gas of EDC 50 vol 1% and nitrogen 50 vol 1%. Reaction conditions are normal pressure, reaction temperature 300 ° C, GHS
V860hr- ¹ . All the reaction products were quantified by gas chromatography. FIG. 1 shows the change with time of the EDC conversion. The results of the reaction for 8 hours are shown in Table 3.

Example 2 The Cs-O / E powder obtained in Example 1 was subjected to a cesium chloride supporting treatment. To 15 g of Cs-O / E, silica gel (SiO ₂ : 30 wt%) was added as a binder so as to be 20 wt%, and after adding an appropriate amount of water, 0.9 g of cesium chloride was added thereto (salt). The solid was evaporated to dryness with stirring, and the same treatment as in Example 1 was performed.

Using this catalyst, a dehydrochlorination reaction of EDC was performed in the same manner as in Example 1. Table 3 shows the results of the reaction for 8 hours.

Example 3 Silica sol (SiO ₂ : 30% by weight) was added as a binder to the Cs-O / E powder obtained in Example 1 so as to have a concentration of 20% by weight, an appropriate amount of water was added, and the mixture was stirred and evaporated to dryness. After pulverization, graphite was added so as to be 5 wt%. This is 5mmφ × 2mL
Then, it was air-fired at 540 ° C. for 3 hours under air flow. The Cs-O / E molded catalyst thus obtained was subjected to a cesium chloride supporting treatment. Cesium chloride aqueous solution (0.45g /
17 ml) was dropped onto 15 g of the Cs-O / E molded catalyst (salt loading 3).
%) And dried at 120 ° C. for 16 hours. This catalyst was calcined at 540 ° C. for 3 hours under flowing air.

Using this catalyst, a dehydrochlorination reaction of EDC was performed in the same manner as in Example 1. Table 3 shows the results of the reaction for 8 hours.

Comparative Example 1 Using the Cs-O / E molded catalyst obtained in Example 3, Example 1
A dehydrochlorination reaction of EDC was carried out in the same manner as described above. FIG. 1 shows the change with time of the EDC conversion. The results of the reaction for 8 hours are as shown in Table 3.

Example 4 The zeolite OE powder obtained in Example 1 was subjected to a K ion exchange treatment. 35 g of zeolite OE was added to an aqueous potassium chloride solution (1mo
(l / l) 250 g, and an ion exchange treatment was performed at 90 ° C. for 5 hours. Thereafter, the slurry was filtered, the obtained solid was sufficiently washed with water, and then dried at 120 ° C. for 16 hours. The composition of the K ion exchanged zeolite OE (hereinafter abbreviated as K-O / E) was _{0.01Na 2 O · 0.98K 2 O ·} Al 2 O 3 · 7.1SiO 2. Silica sol (SiO 2)
₂ : 30wt%) to 20wt%, add an appropriate amount of water, evaporate to dryness while stirring, pulverize graphite 5w
t%. This was compression-molded into 5 mmφ × 2 mmL, and then air-baked at 540 ° C. for 3 hours under air flow.

The KO / E molded catalyst thus obtained was subjected to a cesium nitrate supporting treatment. Cesium nitrate aqueous solution (0.52g / 17ml)
Was dropped onto 15 g of the K-O / E molded catalyst (3.5% salt loading), and 1
Dried at 20 ° C. for 16 hours. 540 ° C under air circulation
For 3 hours. Using this catalyst, a dehydrochlorination reaction of EDC was performed in the same manner as in Example 1. Table 3 shows the results of the reaction for 8 hours.

Example 5 The KO / E molded catalyst obtained in Example 4 was subjected to a cesium chloride supporting treatment. Cesium chloride aqueous solution (0.75g / 17ml)
-Drop on 15 g of O / E shaped catalyst (5% salt loading), 120 ° C
For 16 hours. This catalyst is heated at 540 ° C under air
It was baked for hours. Using this catalyst, a dehydrochlorination reaction of EDC was performed in the same manner as in Example 1. Table 3 shows the results of the reaction for 8 hours.

Example 6 The KO / E molded catalyst obtained in Example 4 was subjected to a rubidium nitrate supporting treatment. Rubidium nitrate aqueous solution (0.39g / 17ml)
Was dropped onto 15 g of the K-O / E molded catalyst (2.6% salt loading),
Dried at 20 ° C. for 16 hours. 540 ° C under air circulation
For 3 hours. Using this catalyst, a dehydrochlorination reaction of EDC was performed in the same manner as in Example 1. Table 3 shows the results of the reaction for 8 hours.

Example 7 The KO / E molded catalyst obtained in Example 4 was subjected to a rubidium chloride supporting treatment. Rubidium chloride aqueous solution (0.75g / 17ml)
Was dropped onto 15 g of the KO / E molded catalyst (5% salt loading),
Dry at 0 ° C. for 16 hours. This catalyst was calcined at 540 ° C. for 3 hours under flowing air. Using this catalyst, a dehydrochlorination reaction of EDC was performed in the same manner as in Example 1. Table 3 shows the results of the reaction for 8 hours.

Comparative Example 2 Using the KO / E molded catalyst obtained in Example 4, Example 1
A dehydrochlorination reaction of EDC was carried out in the same manner as described above. Table 3 shows the results of the reaction for 8 hours.

Example 8 Using the cesium chloride-supported Cs-O / E molded catalyst obtained in Example 3, a dehydrochlorination reaction of EDC was performed in the same manner as in Example 1. Table 4 shows the results of the reaction for 50 hours.

Comparative Example 3 Using the Cs-O / E molded catalyst obtained in Example 3, Example 1
A dehydrochlorination reaction of EDC was carried out in the same manner as described above. Table 4 shows the results of the reaction for 50 hours.

Example 9 The Cs-O / E molded catalyst obtained in Example 3 was subjected to a cesium chloride supporting treatment. Csium chloride aqueous solution (1.5g / 17ml)
-Drop on 15 g of O / E molded catalyst (10% salt loading), 120 ° C
For 16 hours. This catalyst is heated at 540 ° C under air
It was baked for hours. A dehydrochlorination reaction of EDC was performed using this catalyst. 10g of the catalyst is placed in a SUS-316 reaction tube (20mm
φ500mmL) and add 50vol% EDC and 50vo nitrogen to the catalyst
l% feed gas was supplied. Reaction conditions are pressure 12kg / cm
² G, reaction temperature 300 ° C., GHSV 860 hr ⁻¹ . The quantification of the reaction product was performed in the same manner as in Example 1. Table 5 shows the results of the reaction for 8 hours.

Example 10 The Cs-O / E molded catalyst obtained in Example 3 was subjected to a cesium chloride supporting treatment. Cs-O solution of cesium chloride solution (3g / 17ml)
/ E dropped onto 15 g of molded catalyst (salt loading 20%).
Dried for hours. This catalyst was calcined at 540 ° C. for 3 hours under flowing air.

Using this catalyst, a dehydrochlorination reaction of EDC was performed in the same manner as in Example 9. Table 5 shows the results of the reaction for 8 hours.

Comparative Example 4 Using the Cs-O / E molded catalyst obtained in Example 3, Example 9
A dehydrochlorination reaction of EDC was carried out in the same manner as described above. Table 5 shows the results of the reaction for 8 hours.

Example 11 To 15 g of the Cs-O / E powder obtained in Example 3, silica gel (SiO ₂ : 30 wt%) was added as a binder so as to be 20 wt%, and an appropriate amount of water was added. Thereafter, the mixture was evaporated to dryness with stirring. Then add 0.9 g of cesium chloride to this,
The mixture was ground and mixed in a mortar (salt mixing amount 5%). Then Example 1
The same processing as described above was performed. EDC dehydrochlorination was carried out in the same manner as in Example 1 using the obtained catalyst. The results of the reaction for 8 hours are shown in Table 6.

Example 12 Silica sol (SiO ₂ : 30 wt%) was added as a binder to 15 g of KO / E obtained in Example 4 so as to be 20 wt%, and an appropriate amount of water was added. And evaporated to dryness with stirring. Thereafter, 0.9 g of cesium chloride was added to the mixture, and the mixture was pulverized and mixed in a mortar (salt mixing amount: 5%). Thereafter, the same processing as in Example 1 was performed. Example 1 using the obtained catalyst
The EDC was subjected to a dehydrochlorination reaction in the same manner as described above. The results of the reaction for 8 hours are shown in Table 6.

[Brief description of the drawings]

FIG. 1 shows the method according to the invention and the method for comparison.
4 is a graph showing a change over time in an EDC conversion rate in a dehydrochlorination reaction of EDC. In the figure, (1) shows Cs-O / E loaded with 1% of CsCl, and (2)
Indicates a change over time when Cs-O / E is used.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-252433 (JP, A) JP-A-54-79209 (JP, A) JP-A-61-30 (JP, A) JP-A-58-58 16756 (JP, A) JP-A-61-197531 (JP, A) JP-A-55-118426 (JP, A) JP-A-55-94325 (JP, A) JP-B-33-7970 (JP, B1)

Claims (2)

(57) [Claims] 1. An offretite-erionite zeolite whose exchangeable cation is one or more metal cations selected from the group consisting of alkali metals, and one or more metal cations selected from the group consisting of alkali metals. A method for dehydrohalogenating a halogenated saturated hydrocarbon, comprising contacting a catalyst obtained by mixing a salt containing a halogenated hydrocarbon with a halogenated saturated hydrocarbon having 2 to 6 carbon atoms. 2. The method according to claim 1, wherein a catalyst obtained by mixing a salt containing a metal cation with an offretite-erionite zeolite by a supporting method is used.