JP2003290627A - Decomposition reaction process utilizing compounded chemical reaction field - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a certain and economical treatment technique in place of simple incineration with respect to a chemical substance to be decomposed. <P>SOLUTION: A decomposition reaction process is constituted so that at least one kind of a substance to be decomposed selected from a nitrogen-containing organic chemical substance, hydrocarbons and an organochlorine compound is added to the first reaction field and subsequently subjected to decomposition reaction being the second reaction. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a chemical reaction process for decomposing harmful substances.

[0002]

2. Description of the Related Art Up to now, simple oxidative thermal decomposition (incineration) has been widely used as a method for treating chemical substances, but in this case, a by-product which is more toxic than the original substance may be produced. In addition, when the chemical substance to be treated is discharged at a low concentration, a large amount of energy is required per unit amount of treatment for complete detoxification at high temperature. For example, it has been pointed out that nitrogen-containing organic chemical substances are highly toxic to the human body such as carcinogenicity, and it is suggested that nitrile compounds are toxic not only in Japan but also in Europe and America. Typical examples thereof include acrylonitrile. Annual release to the environment is about 15
It is estimated to be 00 tons, and is designated as one of 22 priority action substances among the air pollutants specified by the Ministry of the Environment. The half-life in the atmosphere is estimated to be 2-4 days, the residence time is considerably longer than that of formaldehyde (several hours), and in addition, NOx and HCN which are harmful are generated by the combustion process. There is a need for a new technology to prevent atmospheric release of nitrogen-containing harmful organic compounds including nitrile compounds. Based on these needs, new processing technologies using special reaction fields such as supercritical state, electrochemical, photochemical, and low-temperature plasma are being studied, but so far, versatile technology has not been completed. .

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a reliable and economical treatment technique for a target chemical substance to be decomposed, which can replace simple incineration. It is an issue.

[0004]

[Means for Solving the Problems] As a result of conducting research to solve the above problems, the target substance to be decomposed was
Accelerating the decomposition reaction (second reaction) of the target substance by adding it to the easily advancing reaction (this is the first reaction) field such as H ₂ -O ₂ reaction on Pt catalyst I found that I could do it.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The first reaction used in the present invention is not particularly limited, but for example, H ₂ -O ₂ , ethanol-O ₂ , methanol-O ₂ reaction on an oxidation catalyst such as Pt. And so on. Also, regarding the chemical substances to be decomposed,
There is no particular limitation, but acrylonitrile, acetonitrile
Examples thereof include nitrogen-containing compounds such as N, N-dimethylformamide, hydrocarbons such as ethylene, propylene, butene, benzene, toluene and xylene, and organic chlorine compounds such as tetrachloroethylene, trichloroethylene and dichloromethane.

(Example) The present invention will be specifically described below. Example 1 Granular silicon carbide (SiC) was impregnated with Pt (NH ₃ ) ₄ (OH) ₂ and fired to obtain Pt (Pt / SiC) supported on SiC (Pt = 0.3wt).
%). The reaction was carried out by the programmed temperature method (TPR) using a fixed bed flow reactor. 200ppm acrylonitrile + 1% H ₂ + as reaction gas to 0.5g catalyst sample 7% H ₂ O + Ten% O ₂ (N ₂
Dilution) was run at 500 ml / min. The temperature was raised from 80 ° C to 3 ° C / min, and the CO ₂ concentration produced by the burning of acrylonitrile during that period was continuously analyzed by non-dispersive IR.

Example 2 Alumina supported by supporting a catalyst sample on SiC in Example 1
Acrylonitrile decomposition reaction was carried out in the same manner except that Pt (Pt / Al ₂ O ₃ / SiC) was used.

Example 3 Silica-supported Pt in which the catalyst sample was supported on SiC in Example 1
Acrylonitrile decomposition reaction was performed in the same manner except that (Pt / SiO ₂ / SiC) was used.

Example 4 The same procedure as in Example 1 was repeated except that the decomposition target was 200 ppm acetonitrile instead of acrylonitrile.

Example 5 In Example 1, 0.33% of 1% hydrogen was contained in the components of the reaction gas.
The same procedure was performed except that ethanol was used and the decomposition product was 200 ppm acetonitrile.

Comparative Example 1 The same procedure as in Example 1 was repeated except that the reaction gas was not added with hydrogen. Comparative Example 2 Instead of acrylonitrile as the decomposition product in Example 1,
The same procedure was performed except that 200 ppm acetonitrile was used. Comparative Example 3 The same procedure as in Example 5 was carried out except that the reaction gas was not added to ethanol. The results are shown in Table 1.

[0012]

[Table 1]

Example 6 Alumina (Al ₂ O ₃ ) was impregnated with H ₂ PtCl ₆ and calcined to obtain an alumina-supported Pt (Pt / Al ₂ O ₃ ) catalyst (Pt = 1 wt%). For the reaction, the reactivity in the steady state at each temperature was investigated using a fixed bed flow reactor. To a catalyst sample of 0.2 g, a reaction gas of 1000 ppm hydrocarbon (C ₂ H ₄ or C ₃ H ₆ , 1-C ₄ H ₈ , cis-2-C ₄ H ₈ , i-C _{4
H 8) + 1% H 2} + 2% O 2 and (He dilution) was run 100 ml / min. When the catalyst bed temperature reached a steady state, the CO ₂ concentration produced by the combustion of hydrocarbons was analyzed by gas chromatography. The results are shown in Table 2.

[0014]

[Table 2] Example 7. In Example 6, the catalyst sample was Ir supported on alumina.
Hydrocarbons were burned in the same manner except that (Ir / Al ₂ O ₃ ) was used. The results are shown in Table 3.

[0015]

[Table 3]

[0016]

[Effects of the Invention] As is clear from Tables 1, 2, and 3, the rate of decomposition of the substance to be decomposed into CO ₂ is better under the reaction conditions in which H ₂ or ethanol is present and these oxidation reactions are in progress. Is particularly high in the low temperature region. That is, according to the present invention, a chemical substance can be efficiently treated at a low temperature.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akihiko Oi             1-1-1 Higashi 1-1-1 Tsukuba City, Ibaraki Prefecture             Inside the Tsukuba center (72) Inventor Norio Nakayama             1-1-1 Higashi 1-1-1 Tsukuba City, Ibaraki Prefecture             Inside the Tsukuba center F term (reference) 2E191 BA11 BA12 BD13                 4D048 AA17 AB01 AB03 BA03X                       BA06X BA30X BA33X BA41X                       BA45X                 4G069 AA03 AA08 BA01B BA02B                       BB15B BC74B BC75B BD05B                       CA07 CA10 CA11 DA06 FB14

Claims (8)

[Claims] 1. One or more substances to be decomposed selected from nitrogen-containing organic chemicals, hydrocarbons, and organic chlorine compounds are added to the first reaction site, and then in the second reaction. A decomposition reaction process that performs a certain decomposition reaction. 2. The decomposition reaction process according to claim 1, wherein the reaction of the second reaction is an oxidation reaction. 3. The decomposition reaction process according to claim 1, wherein the nitrogen-containing organic chemical substance is a nitrile, the hydrocarbons are ethylene, propylene, butene, and the organic chlorine compound is tetrachloroethylene, trichloroethylene, or dichloromethane. 4. The first reaction is H ₂ on a Pt or Pd catalyst.
The decomposition reaction process according to claim 1, which is a -O ₂ reaction and the decomposition target substance is a nitrile. 5. The first reaction is ethanol-O on a Pt catalyst.
_The decomposition reaction process according to claim 1, which is a _two- reaction, and the decomposition target substance is a nitrile. 6. The decomposition reaction process according to claim 4, wherein the nitriles are acrylonitrile or acetonitrile. 7. The decomposition reaction process according to claim 1, wherein the first reaction is a H ₂ —O ₂ reaction on a Pt, Ir or Rh catalyst, and the substance to be decomposed is a hydrocarbon. 8. The decomposition reaction process according to claim 5, wherein the nitriles are acrylonitrile or acetonitrile.