JPH0427901B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an unsaturated hydrocarbon absorbent, and more particularly to a method for producing the above-mentioned solid separation agent that selectively absorbs unsaturated hydrocarbons and has excellent water resistance. Conventionally, as an agent for absorption and separation of unsaturated hydrocarbon gases such as ethylene _{and propylene} , compounds with the formula M _{1 M 11} -A group metal, X: halogen, aromatic:
A liquid absorbent consisting of an aromatic hydrocarbon or halogenated aromatic hydrocarbon solution of a dimetal salt complex of C ₆ to ₁₂ monocyclic aromatic hydrocarbon or halogenated aromatic hydrocarbon −21328), CuAlX ₄
(X: halogen atom)
48-35041), but in all of these, the effective gas absorption ingredients themselves are unstable, and the absorption performance deteriorates in a short period of time, especially if moisture is present in the gas to be treated. There were flaws. In addition, recently, the above-mentioned complex in liquid or solid form consisting of silver halide, aluminum halide (), and polystyrene has been announced as a polymeric metal complex having the ability to separate ethylene from a mixed gas (Chemical Society of Japan). (See ``Polymer Metal Complex with Ethylene Separation Function'' by Hirai et al., 1983 Autumn Annual Meeting 2103). However, like the unsaturated hydrocarbon absorbent described above, this complex is highly susceptible to moisture deterioration in a liquid state, and cannot stably absorb and separate ethylene for a long period of time. The present invention eliminates these drawbacks and proposes a method for producing a solid unsaturated hydrocarbon absorbent that has highly selective absorption and separation performance for unsaturated hydrocarbons and has excellent water resistance. It is. That is, the present invention relates to a method for producing an absorbent for unsaturated hydrocarbons, which comprises dissolving silver perchlorate in an aromatic compound, bringing the solution into sufficient contact with a porous inorganic oxide, and then removing free organic solvent. It is something. Note that the unsaturated hydrocarbons targeted in the present invention are a general term for unsaturated hydrocarbons such as olefins such as ethylene, propylene, and butene, dienes such as butadiene, and acetylenes. (below,
These are referred to as ethylenes) Benzene, toluene, xylene, etc. are used as aromatic compounds in the present invention. However, solvents that do not have the ability to dissolve silver perchlorate or solvents that decompose, reduce, or oxidize are not preferred.
Furthermore, since the desorption operation of this absorbent after absorption of ethylene is usually carried out under heating or reduced pressure, low boiling point solvents or high volatility solvents are not preferred. This is because silver perchlorate forms a complex with an aromatic compound and is stabilized on an inorganic oxide in the absorption/separation agent according to the method of the present invention, but the aromatic compound has a low boiling point or high volatility. This is because the complex would be decomposed by heating or reduced pressure under desorption conditions.
It is known that silver perchlorate and benzene form a stable complex. (J.Am.Chm.Soc. 80
5075 (1958)) In the method of the present invention, silver perchlorate is dissolved in an aromatic compound and brought into sufficient contact with a porous inorganic oxide. As the contact method, impregnation method, dipping method, spraying method, etc. are adopted, and among them, the impregnation method is generally used, which does not use more organic solvent than necessary and uses an amount of solvent that is approximately equal to the pore volume of the carrier. It is. The ability of silver to act as an absorbent according to the method of the invention shows significant ethylene selectivity and absorption when silver is operating in its monovalent state. Therefore, in order for silver perchlorate to form a stable complex salt with an aromatic compound, the silver perchlorate solution is brought into sufficient contact with the porous inorganic oxide, and then the solution is heated for 40 minutes in the absence of moisture, preferably in an inert gas. A heating operation is performed at ~60°C for 6 to 8 hours. Through this heating operation, a complex salt consisting of silver perchlorate and the aromatic compound is formed, and it is presumed that the complex salt also forms some kind of bond with the porous inorganic oxide of the carrier. The concentration of silver perchlorate in the aromatic compound may be as high as desired as long as the temperature is such that silver perchlorate can be dissolved, and there is no need to dilute it more than necessary. Generally, the solution concentration and amount may be such that silver perchlorate is supported in an amount of 5 to 50 wt% based on the inorganic oxide. Further, the porous inorganic oxide used is one that allows silver perchlorate to be sufficiently dispersed and has conditions that do not react with silver perchlorate to liberate perchlorate ions. Examples of the porous inorganic oxide generally include alumina, titania, silica, silica-magnesium, and silica-alumina. In addition, if the surface area of this porous inorganic oxide is too large, the pores will be small and the dispersibility of the complex salt will be reduced.
BET surface area from 40 to 400 m ² /g, preferably from 50 to
300m ² /g is used. Of these, 500~
Porous inorganic oxides, especially alumina, calcined at 900° C. and having a surface area of 50 to 300 m ² /g are preferred. In the method of the present invention, after the above-mentioned contacting and heating operations, the free organic solvent is removed under reduced pressure. At this time, the same heating as described above (that is, heating at 40 to 60° C. in a moisture-free state, preferably in an inert gas) can also be applied. It is important to carry out this removal operation until the organic solvent in the liquid phase is exhausted. This is because the solid absorption and separation agent produced by the method of the present invention exhibits sufficient water resistance when Ag() is completely immobilized in the porous inorganic oxide, and when the free organic solvent is in the liquid phase. This is because, if it remains retained in the pores, the selective absorption performance of ethylene will be easily deteriorated by water, as seen in the above-mentioned conventional liquid absorbent. Hereinafter, the method of the present invention will be explained in more detail with reference to Examples. Example 1 Silver perchlorate was a commercially available special grade reagent (here, one made by Kojima Chemical Co., Ltd. was used as is), and toluene was a commercially available special grade reagent (here, made by Wako Pure Chemical Industries, Ltd.), which was mixed with metallic sodium. After dehydration, it was distilled and used. 1.24 g (6 m-mol) of the above silver perchlorate and toluene were placed in a 200 ml two-necked eggplant flask under dry nitrogen.
20 ml of the solution was added and heated and kept at 60°C for 2 hours while stirring with a magnetic stirrer. The nitrogen mentioned above is commercially available nitrogen (here, 99.999% purity manufactured by Teikoku Sanso Co., Ltd.), and immediately before use, it is mixed with a commercially available molecular sieve.
3A (here manufactured by Nikka Seiko Co., Ltd.) was purified by passing it through a column filled with it. On the other hand, in another 200 ml two-necked eggplant flask, 10 pieces of alumina A carrier (manufactured by Catalyst Kasei, average pore diameter 108 Å, BET surface area 230 m ² /g) was calcined at 550°C for 3 hours.
After fully deaerating the inside of the eggplant flask using a vacuum pump, the previously prepared toluene solution of silver perchlorate was added thereto using a dropping funnel. After stirring for 10 minutes, reduce the pressure inside the eggplant flask (6 mmHg) and evacuate it all day and night.
An absorbent was prepared by sufficiently removing toluene. The amount of absorbent thus obtained was 11.7 g. To confirm the performance of this absorbent, a mixed gas of 1 atm ethylene and nitrogen (ethylene partial pressure 0.80 atm,
Nitrogen partial pressure 0.20 atm) was aerated. Absorption operation at 23℃
Using an air pump to pump the mixed gas at 1.4/m
This was done by circulating the mixture over the absorbent. The mixed gas of ethylene and nitrogen used was a commercially available product (purity ethylene 79.99%, nitrogen 20.01% manufactured by Tetsuko Kagaku Kogyo Co., Ltd.). In this case, the amount of ethylene absorbed is 4.2 m in 10 minutes.
It was hot in mol. The absorbent was then heated to 90°C at 1 atm to release the absorbed ethylene. Thereafter, water treatment, absorption, and release were repeated, and the amount of ethylene absorbed was measured. The results are shown in Table 1 below. Examples 2 to 3 The same operations as in Example 1 were performed except that benzene and xylene were used instead of toluene in Example 1. The results are also shown in Table 1 below. Benzene is Example 2, and xylene is Example 3. Example 4 Silica (B.
The same procedure as in Example 1 was carried out except that an ET surface area of 251 m ² /g) was used. The amount of ethylene absorbed is also shown in Table 1.

[Table] Ivy.
Example 5 The same absorbent as in Example 1 was prepared, and the mixed gas to be absorbed was replaced with ethylene and nitrogen.
Similar adsorption/desorption experiments were repeated using a mixed gas of 1 atm acetylene and nitrogen (acetylene partial pressure 0.78 atm, nitrogen partial pressure 0.22 atm), and the results shown in Table 2 were obtained.

[Table] Comparative Example 1 For silver perchlorate, a commercially available special grade reagent (here manufactured by Kojima Chemical Co., Ltd.) was used as is, and toluene was a commercially available special grade reagent (here manufactured by Wako Pure Chemical Industries, Ltd.). ) is dehydrated with metallic sodium,
It was distilled and used. 1.24 g (6 m-mol) of the above silver perchlorate and toluene were placed in a 200 ml two-necked eggplant flask under dry nitrogen.
20 ml of the solution was added, and heated and kept at 60°C for 2 hours while stirring with a magnetic stirrer. The above nitrogen is commercially available nitrogen (purity 99.999 manufactured by Teikoku Sanso Co., Ltd.).
%) was purified by passing it through a column filled with commercially available molecular sieve 3A (here manufactured by Nikka Seiko Co., Ltd.) immediately before use. To confirm the performance of the obtained liquid absorbent,
A mixed gas of 1 atm of ethylene and nitrogen (ethylene partial pressure 0.80 atm, nitrogen partial pressure 0.20 atm) was bubbled through. The absorption operation is performed using a mixed gas at 23℃ using an air pump.
This was done by passing it over the absorbent with circulation at 1.4/m. The mixed gas of ethylene and nitrogen used was a commercially available product (purity of ethylene 79.99% and nitrogen 20.01% manufactured by Steel Chemical Industry Co., Ltd.). In this case, the amount of ethylene absorbed is 2.7 m- in 10 minutes.
It was hot in mol. The absorbent was then heated to 90°C at 1 atm to release the absorbed ethylene. After that, water treatment, absorption,
The release was repeated and the amount of ethylene absorbed was measured. As a result, the amount was 3.0 m-mol after one water treatment, and 2.4 m-mol after two water treatments. Comparative Example 2 6 mmol of silver nitrate was dissolved in 20 ml of water, impregnated into 10 g of alumina A carrier calcined at 550°C for 3 hours, and evaporated to dryness to obtain an absorbent. This absorbent absorbed 3.9 m-mol of ethylene before water treatment, but the absorption capacity decreased to 2.7 m-mol after water treatment.

Claims (1)

[Claims] 1. A method for producing an unsaturated hydrocarbon absorbent, which comprises bringing a solution consisting of silver perchlorate and an aromatic compound into sufficient contact with a porous inorganic oxide, and then removing free organic solvent. . 2 Fired at 500-900℃, surface area 50-300
2. A method according to claim 1, characterized in that a porous inorganic oxide with a density of m ² /g is used.