JP2911961B2 - High concentration alcohol purification method and adsorbent for purification - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention [Industrial Application Field] In chemical reactions using alcohols, there are some which by-produce sulfur compounds such as dimethyl disulfide (DMDS) and mercaptan.

For example, the following reaction in which nitrochlorobenzene is ethoxylated with ethanol in dimethyl sulfoxide (DMSO) solvent to synthesize p-nitrophenetole In this method, excess ethanol is recovered and reused after the completion of the reaction, but the above-mentioned sulfur compound is by-produced in the reaction and the alcohol recovery step.

When ethanol containing DMDS or mercaptan is recovered and reused, DMDS or mercaptan accumulates in the reaction product, and migrates to p-nitrophenetole during separation.

The p-nitrophenetole is then hydrogenated to p-aminophenetole (phenetidine), where the catalyst (Pd / activated carbon) is recovered because it is poisoned by sulfur compounds such as DMDS and mercaptan. In circulating alcohol
DMDS and mercaptans need to be removed. Some of the sulfur compounds that are problematic in the hydrogenation step include sulfur compounds attached to the benzene ring. Since these are formed from the sulfur compounds in the alcohol, the sulfur compounds (particularly DMDS) in the recovered alcohol are removed. It is necessary to remove it to 10 ppm or less. Since removal cannot be sufficiently performed by the distillation method, development of a removal method has been required.

The recovered alcohol contains dimethylsulfide (DMS) and DMSO used as a solvent in addition to DMDS and mercaptan, but it is known that DMS and DMSO do not become catalyst poisons.

[Prior Art] Various adsorbents for sulfur compounds are known. For example, in the literature (J. Chem. Soc. Faraday Trans. 1, 1988, 8
4 (9), 3027-3041, 3043-3057) includes Fe, Ni, Al, Cu, P
d metal or its metal oxide is mercaptan or DMS, DMDS
Has been shown to adsorb well. Other documents (Katayama, Idemitsu Petroleum Technology vol. 30, p. 182-187, 1987) describe that sulfur compounds in hydrocarbons adhere to Cu and Ag test pieces and corrode. Does not suggest its use as an adsorbent.

Another problem is whether all of the adsorbents composed of these metals and metal oxides are effective in removing specific sulfur compounds in a high-concentration aqueous alcohol solution. According to the study of the present inventors, it was found that DMDS in the recovered alcohol adsorbed well to Cu and Pd when the alcohol concentration was low, but hardly adsorbed when the alcohol concentration was high.

It is not advisable to adsorb and remove all sulfur compounds in the recovered alcohol. Because much higher amounts of harmful DMDS and mercaptans are
Since it contains DMSO, the adsorption capacity of the adsorbent is quickly saturated when all these sulfur compounds are adsorbed,
This is because a large amount of adsorbent is required.

[Problems to be Solved by the Invention] The present invention provides a method for purifying a high-concentration alcohol, which selectively adsorbs only DMDS or mercaptan in a high-concentration aqueous alcohol solution and does not adsorb and remove DMSO or DMS, and an adsorbent for purification. The purpose is to:

B. Constitution of the Invention [Means for Solving the Problems] The method for purifying a high-concentration alcohol according to the present invention is a method for purifying a high-concentration alcohol solution containing at least dimethyl disulfide as a sulfur compound at an alcohol concentration of 60 vol% or more with silver or silver oxide. , Alumina, and silica to remove dimethyl disulphide by contact with an adsorbent supported on a porous carrier selected from the group consisting of alumina, or an alcohol concentration containing at least dimethyl disulfide and mercaptan as sulfur compounds of 60 vol% It is characterized in that dimethyl disulfide and mercaptan are adsorbed and removed by bringing the above high-concentration alcohol aqueous solution into contact with an adsorbent carried on a porous carrier selected from the group consisting of activated carbon, alumina, and silica-alumina with silver or silver oxide. And

The high-concentration alcohol purification adsorbent is characterized in that silver or silver oxide is supported on a porous carrier selected from the group consisting of activated carbon, alumina, and silica-alumina.

In the present invention, the high-concentration alcohol means alcohol containing at least 60 vol% or more. When the alcohol concentration is less than 60 vol%, other metals can be used, so that it is not necessary to apply the present invention.

The alcohol separated and recovered after the reaction of the formula (1) contains 20 ppm or more of DMDS and 1000 ppm or more of DMSO as sulfur compounds, and it is necessary to reduce the DMDS to 10 ppm or less.

Silver or silver oxide is used as an active ingredient of the adsorbent that selectively adsorbs only DMDS, but silver oxide is preferred in terms of easy regeneration. Silver is regenerated with hydrogen, but requires higher temperatures than oxidative regeneration, and the use of hydrogen is disadvantageous. In the case of silver oxide, the original state can be recovered in a short time by regenerating at about 400 ° C. using air. Activated carbon, alumina and silica-alumina are suitable as the carrier. This is for supporting silver in a highly dispersed state. Activated carbon is not added as a silver oxide carrier because it is oxidized during regeneration.

The adsorption operation is preferably performed at room temperature or lower than the boiling point of alcohol (boiling point of ethanol: 78.3 ° C.). The higher the temperature, the faster the adsorption, but above the boiling point, a pressurized vessel is required,
Further, a heat source for heating is required, which is uneconomical.

The adsorbent in the present invention can be repeatedly used by performing a regeneration treatment.

In the case of silver, the temperature is 400 ° C or more, especially 500 ° C due to hydrogen.
It is preferable to regenerate at the above temperature.

AgS + H ₂ → Ag + H ₂ S In the case of silver oxide, reproduction is possible at 300 ° C. or higher using an oxygen-containing gas.

AgS + O ₂ → AgO + SO ₂ Air may be used as the oxygen-containing gas. However, it is necessary to drive off the adsorbed alcohol with an inert gas or water vapor before introducing air.

Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to the following examples.

[Example 1] (Batch method adsorption experiment) The ethanol recovered in the synthesis process of p-nitrophenetol according to the above formula (1) was used. The composition was as follows: alcohol concentration = 95 vol%, DMDS = 23 ppm, DMSO = 5300 ppm.

0.5 g of the various adsorbents shown in Table 1 was added to 50 ml of the above raw material, and the mixture was shaken at room temperature for 60 minutes. Then, the adsorbent was separated by filtration, and the filtrate was analyzed by gas chromatography (FPD detector).

As the adsorbent, an aqueous solution of a metal nitrate or hydrochloride is supported on the carrier by an impregnation method, and then calcined at 500 ° C and further hydrogenated for 300 minutes.
C. for 3 hours. In the case of an oxide, it was used only by firing. The amount of metal carried was 1.0 wt% as metal. The results are shown in Table 1.

Table 1 shows that silver or silver oxide is excellent as an adsorbent, and that alimina, silica alumina and activated carbon are excellent as carriers.

DMSO is not adsorbed at all, but since it does not need to be removed because it does not poison the catalyst in a later step, there is an advantage that there is no possibility that the adsorption capacity is reduced by DMSO adsorption.

[Example 2] (Adsorption experiment of flow method) Adsorbent having a particle diameter of 1 mm (the amount of supported metal is the same as in Example 1) 5
g was packed in a 10 mm diameter (diameter) glass column, and an adsorption experiment was carried out to determine the flow rate of the raw material until the DMDS passed (the flow rate of the raw material was 5 ml / min). After the breakthrough, DMDS was regenerated with hydrogen when the adsorbent was silver and air with silver oxide, and the performance after regeneration was measured. The results are shown in Table 2.

Table 2 shows that silver and silver oxide can be compared with each other at a higher temperature and at a lower temperature by comparing silver and silver oxide.

Example 3 (Effect of Silver Carrying Amount) An experiment was conducted in the same manner as in Example 1 except that the amount of silver carried was changed, and the results are shown in Table 3. For comparison, the amount of DMDS per silver was shown.

As shown in Table 3, there is no significant difference in the amount adsorbed per silver up to a silver loading of 5 wt%, but at 10 wt% the amount adsorbed per silver is slightly reduced.

[Reference Example 1] (Adsorption of methyl mercaptan) Since the concentration of methyl mercaptan in the raw material was low, it was difficult to accurately determine the amount of adsorption in the above-mentioned adsorption experiment.
Separate adsorption experiments were performed for methyl mercaptan.

The same experiment as in Example 1 was performed using a raw material obtained by adding 30 ppm of methyl mercaptan to 95 vol% ethanol, and the change in the mercaptan concentration on the liquid side was measured. The results are shown in Table 4.

As shown in Table 4, it was found that silver oxide adsorbs mercaptan to the same extent as copper.

Note that dimethyl sulfide did not adsorb to these three adsorbents at all. Dimethyl sulfide is known not to poison the catalyst in the next hydrogenation step and does not need to be removed.

C. Effects of the Invention 1) Sulfur compounds such as dimethyl disulfide and mercaptan in highly concentrated alcohol can be reduced to 10 ppm or less.

2) Since the adsorbent can be used repeatedly, the processing cost is low.

3) Continuous operation becomes possible by having two adsorption towers.

4) Operation becomes easy.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C07C 29/76 B01J 20 / 02,20 / 06

Claims (3)

(57) [Claims] 1. A high-concentration aqueous alcohol solution containing at least dimethyl disulfide as a sulfur compound and having an alcohol concentration of 60 vol% or more is activated silver, silver oxide, activated carbon, alumina,
A method for purifying a high-concentration alcohol, comprising adsorbing and removing dimethyl disulfide by contacting with an adsorbent supported on a porous carrier selected from the group consisting of silica and alumina. 2. An alcohol containing at least dimethyl disulfide and mercaptan as sulfur compounds at an alcohol concentration of 60 vol.
By adsorbing and removing dimethyl disulfide and mercaptan by bringing silver or silver oxide into contact with an adsorbent supported on a porous carrier selected from the group consisting of activated carbon, alumina, and silica-alumina with an aqueous solution of a highly concentrated alcohol of l% or more. A method for purifying high-concentration alcohol, characterized by the following. 3. An alcohol containing at least dimethyl disulfide as a sulfur compound, wherein silver or silver oxide is supported on a porous carrier selected from the group consisting of activated carbon, alumina, and silica-alumina.
Adsorbent for purification of high-concentration alcohol solution of vol% or more.