JP2001115136A - Production of metal scavenger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for efficiently and inexpensively producing a metal scavenger having dithioate groups as functional groups. SOLUTION: This process comprises reacting a polyalkylenepolyamine as a starting material with an alkylene dichloride as a starting material at atmospheric pressure in the presence of water, adding an alkali in an amount at least twice by mole that of the alkylene dichloride to the reaction mixture, and reacting the mixture with carbon disulfide to introduce dithioate groups as functional groups into the product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a metal collecting agent.

[0002]

2. Description of the Related Art Polyalkylene polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine and polyethyleneimine are reacted with carbon disulfide in the presence of an alkali. A method for obtaining a metal collecting agent by introducing a dithioacid group or a dithioacid group as a functional group is known.

[0003] The polyalkylene polyamine used in the above method for producing a metal collecting agent is conventionally produced by reacting ammonia with ethylene dichloride. This reaction must be performed under a high pressure of 10 atm or more. In addition, since a manufacturing apparatus capable of withstanding high pressure is required, a large capital investment is required. For this reason, ethylenediamine, which is in high demand, is provided at a relatively low cost. For example, polyalkylenepolyamines having a higher molecular weight than ethylenediamine, such as diethylenetriamine, tetraethylenepentamine, and pentaethylenehexamine, are twice or more than ethylenediamine. Sold at the price of

Polyethyleneimine is produced by a method of polymerizing cyclic ethyleneimine. Since ethyleneimine is a compound having a low boiling point and high toxicity, special equipment is required for producing polyethyleneimine. Ethyleneimine is not easily available. For this reason, polyethyleneimine is 10 times less than ethylenediamine and the like.
It is sold twice as expensive.

By the way, as a raw material for producing a metal collecting agent, a polyalkylene polyamine having a higher molecular weight than a low molecular weight polyalkylene polyamine such as ethylenediamine or polyethyleneimine having a molecular weight of about 300 or more is useful. However, as described above, since such a compound is more expensive than ethylenediamine, there is a problem that the product cost of the metal collector is high. Also,
Polyalkylene polyamines and polyethylene imines having a higher molecular weight than those conventionally marketed are practically difficult to obtain, and even if they are available, they become extremely expensive, and as a raw material for producing metal trapping agents. Not suitable.

[0006] Furthermore, when a metal collector manufacturer attempts to produce polyalkylene polyamine or polyethyleneimine necessary for the production of its own product by itself, a large capital investment is required, and raw materials are mass-produced. Unless you consume
There is a problem that the product cost of the metal collecting agent, which is the final product, becomes extremely high. Therefore, the metal trapping agent manufacturer must purchase and use the raw material polyalkylene polyamine from the polyamine manufacturer, but the polyalkylene polyamine and polyethylene which can be obtained from the polyamine manufacturer at low cost as the raw material for producing the metal trapping agent. There are relatively few types of imines, which has been a constraint in further improving the performance of the metal collector.

The present invention has been made to solve the above-mentioned problems, and has as its object to provide a method for producing a metal collecting agent which can provide a metal collecting agent having excellent performance at low cost.

[0008]

That is, the method of the present invention for producing a metal collecting agent comprises a step of polycondensing a polyalkylene polyamine and an alkylene dichloride at normal pressure in the presence of water.
It is characterized in that an alkali of at least twice the amount of alkylene dichloride is added, followed by reaction with carbon disulfide to introduce a dithioacid group as a functional group.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The polyalkylene polyamine used in the present invention includes, for example, ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, diethylenetriamine, dipropylenetriamine, dibutylenetriamine, triethylenetetramine, tripropylenetetramine, tribubutylene. Examples thereof include tetramine, tetraethylenepentamine, tetrapropylenepentamine, tetrabutylenepentamine, pentaethylenehexamine, iminobispropylamine, monomethylaminopropylamine, and methyliminobispropylamine. Of these, inexpensive ethylenediamine and diethylenetriamine are preferred.

The above polyalkylene polyamine further comprises N
-A substituent having a hydroxyalkyl group, an acyl group, an alkyl group or the like may be used, but it is necessary that two or more primary amino groups or secondary amino groups remain in one molecule. The N-hydroxyalkyl substituent can be introduced by reacting the polyalkylene polyamine with an epoxy alkane; the N-acyl substituent is introduced by reacting the polyalkylene polyamine with a fatty acid; The alkyl substituent is introduced by reacting the polyalkylene polyamine with an alkyl halide; The N-hydroxyalkyl substituent preferably has 2 to 28 carbon atoms in the alkyl group.
The acyl substituent preferably has 2 to 24 carbon atoms.
The N-alkyl substituent preferably has 2 to 18 carbon atoms.

Examples of the alkylene dichloride to be subjected to the polycondensation reaction with the polyalkylene polyamine include ethylene dichloride, propylene dichloride and the like. As the polyalkylene polyamine and the alkylene dichloride, those having an alkylene group having the same carbon number may be reacted, or those having an alkylene group having a different carbon number may be reacted. When a polyalkylene polyamine having an alkylene group having a different number of carbon atoms was reacted with an alkylene dichloride, and then reacted with carbon disulfide to introduce a dithioacid group as a functional group, different types of alkylene groups were bonded via an amino group. A metal scavenger based on a polyalkyleneamine of the structure is obtained.

In the method of the present invention, the polyalkylene polyamine and the alkylene dichloride can be reacted under normal pressure, but the reaction requires the presence of water. The reaction molar ratio between the polyalkylene polyamine and the alkylene dichloride is preferably from 1: 0.5 to 1.5. By adjusting the reaction ratio between the polyalkylene polyamine and the alkylene dichloride, it is possible to obtain a polyethyleneimine having the same structure as that obtained by polymerizing a cyclic ethyleneimine. In the method of the present invention, water is 5-6.
It is preferred that the compound is present in the reaction system at a ratio of 0% by weight.
If the amount of water is less than 5% by weight, stirring during the reaction becomes difficult,
On the other hand, if it exceeds 60% by weight, the reaction rate will decrease and the yield will deteriorate.

The polyalkylene polyamine and the alkylene dichloride are reacted by, for example, mixing the polyalkylene polyamine in a container equipped with a stirrer, dropping the alkylene dichloride under heating and stirring, and after completion of the dropping, further heating and maintaining the mixture under stirring. . Can be. The temperature at the time of dropping the alkylene dichloride is preferably from 0 to 180 ° C. The dropping time is preferably set to such a time that the reaction heat can be removed. The temperature for heating and holding after the completion of the alkylene dichloride dripping is about 30 to 160 ° C., and the holding time is about 1 to 20 hours.

After the completion of the above reaction, an alkali in an amount of at least twice the amount of the alkylene dichloride added first is added, followed by reaction with carbon disulfide. As the alkali, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide or an alkaline earth metal hydroxide such as calcium hydroxide can be used, and sodium hydroxide is preferable. This alkali separates chlorine bound to the reaction product of the polyalkylene polyamine and the alkylene dichloride as a salt to produce a polyalkylene polyamine having a higher molecular weight than the polyalkylene polyamine used as a starting material, and disulfide It is added to act as a carbon reaction catalyst. When the purpose is to produce a polyalkylene polyamine, the above-mentioned method of reacting an alkylene dichloride with a polyalkyne polyamine as a starting material to produce a polyalkylene polyamine having a higher molecular weight, or a polyalkylene polyamine by reacting ethylene dichloride with ammonia. In any of the conventional methods for obtaining an alkylene polyamine, it is necessary to separate a salt (eg, sodium chloride) generated by the addition of an alkali. The metal collector can be obtained by reacting the generated polyalkylene polyamine with carbon disulfide. Therefore, there is a salt such as sodium chloride in the reaction system containing the metal collecting agent, but the coexistence of the salt does not affect the performance as a metal collecting agent. Can be. Therefore, in the method of the present invention, the steps are simplified.

It is preferable that the amount of carbon disulfide added is not more than (the number of moles of active hydrogen contained in the polyamine-2) or less. 10-100 ° C for carbon disulfide
It is preferable to gradually add dropwise at such a ratio that the heat of reaction can be removed. After completion of carbon disulfide addition, 10-1
By keeping the mixture at 00 ° C. with stirring for 1 to 10 hours, the added carbon disulfide is almost completely reacted. By reacting carbon disulfide with a polycondensation reaction product of polyalkylene polyamine and alkylene dichloride (polyamine) in the presence of an alkali in this manner, the dithioacid is replaced with active hydrogen bonded to the nitrogen atom of the polyamine. A group or a dithioacid group is introduced, and a metal scavenger having a dithioacid group and / or a dithioacid group as a functional group is obtained.

In the method of the present invention, a commercially available polyalkylene polyamine as a starting material can be used. In the method of the present invention, a polyalkylene polyamine as exemplified above can be arbitrarily selected and used as a starting material, but when a low molecular weight material which is commercially available at a low cost such as ethylenediamine is used as a starting material, It is preferable because the intended object of the present invention can be sufficiently achieved.

The metal collecting agent produced by the method of the present invention can be used to collect gaseous metals contained in flue gas, incineration ash from garbage incineration plants, and mines, in addition to collecting metals in wastewater. Solids containing metals such as slag discharged from wastewater, sludge as industrial waste generated by neutralization coagulation sedimentation treatment during wastewater treatment, and sedimentation treatment with a coagulant, highly contaminated soil, fly ash, incineration ash, etc. It can be used for the purpose of immobilizing metals in waste.

[0018]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. Examples 1 to 4 The amounts of polyalkylene polyamine and water shown in Table 1 were charged into a 1-liter four-necked flask equipped with a stirrer, a thermometer, a dropping funnel and a cooler, and stirred under the dropping conditions shown in Table 1. And the amount of alkylenedichloride shown in Table 1 was dropped from the dropping funnel over the time shown in the section of alkylene dichloride dripping conditions in the same table at the same temperature. After completion of the dropwise addition, the polycondensation reaction was carried out while maintaining the reaction system under the alkylene dichloride reaction conditions shown in Table 1 while stirring. Next, an aqueous solution of sodium hydroxide having the concentration shown in Table 1 was added to the flask, and the amount of carbon disulfide shown in the same table was added dropwise at 25 ° C over 3 hours.
It was kept at 40 ° C. for 4 hours to react carbon disulfide. Table 2 shows the average molecular weight (measured by the GPC method) and the introduction rate of the functional group (the substitution rate of the functional group with respect to the amount of the original active hydrogen that can be substituted) of the metal collector thus obtained.

[0019]

[Table 1]

[0020]

[Table 2]

Reference Example 1 According to the method of Example 1, 150 g of an aqueous ammonia solution (28%) was charged instead of the polyalkylene polyamine.
After 278 g of ethylene dichloride was added dropwise at room temperature over 3 hours, the mixture was heated to 95 to 100 ° C. and stirred for 10 hours. Almost all ammonia and ethylene dichloride were recovered, and the consumption of ammonia was 0.5 g. The yield of polyamines based on the amount of ammonia was 1.2%.

[0022]

As described above, according to the method of the present invention, the polyamines obtained by reacting ammonia and alkylene dichloride under high pressure have a higher molecular weight than the conventional method in which a polyamine is used as a starting material for a metal collecting agent. Even metal collectors based on polyalkylene polyamines can be easily and inexpensively manufactured.

Also, polyalkylene polyamines having a higher molecular weight than commercially available polyalkylene polyamines have heretofore been difficult to obtain because of their high cost, but according to the method of the present invention, they are difficult to obtain conventionally. Can be easily and inexpensively manufactured, and as a result, it has not been practically possible in the past to produce a metal collector having a structure based on a high molecular weight polyalkylene polyamine. A metal collecting agent having such a structure can be easily provided. For this reason, the structural range of the metal collecting agent is widened, and the performance of the metal collecting agent can be easily improved in terms of structure.

Furthermore, since the method of the present invention does not require a high-pressure reaction, a metal-catching agent manufacturer starts by producing a polyalkylenepolyamine as a raw material of a metal-catching agent, and then introduces a functional group into this polyamine to carry out metal-catching. The process up to the collection can be performed continuously. For this reason, in the conventional method, a two-step process of purchasing a polyalkylene polyamine produced by a polyamine manufacturer and introducing a functional group into the polyalkylene polyamine to produce a metal catcher by the metal scavenger manufacturer is performed. In contrast to the necessity, the method of the present invention requires only one step, so that the high pressure reaction is not required during the reaction step, and the work efficiency and work cost can be reduced. Can be.

Continued on front page F term (reference) 4D038 AA08 AB58 AB63 AB86 4J043 PA02 PC066 QB15 QB20 QB23 SA06 SA61 SA71 SB01 TA26 TA43 TB01 UB011 UB012 UB241 XA03 XA12 XB02 XB03 YB14 YB37 ZB31

Claims (1)

[Claims] 1. After polycondensation of a polyalkylene polyamine and an alkylene dichloride at normal pressure in the presence of water,
A method for producing a metal collecting agent, comprising adding an alkali at least twice as much as alkylene dichloride and then reacting carbon disulfide to introduce a dithioacid group as a functional group.