JP2002255860A - Method for carrying out decomposition treatment of slightly decomposable halogen compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for carrying out decomposing treatment of an organohalogen compound, enabling stable treatment making the organohalogen compound harmless in good reproducibility, compared with a conventional method in a method for carrying out dehalogenative decomposition treatment of the organohalogen compound by an alkali. SOLUTION: This method for carrying out decomposition treatment of an organohalogen compound by using an alkali in a hermetically sealable reactor is characterized by carrying out dehalogenation reaction of the organohalogen in <3 volume % oxygen concentration of a space part in the above reactor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a hardly decomposable halogen compound such as polychlorinated biphenyl (hereinafter referred to as "P
Abbreviated as "CB") and the like, which are dehalogenated and decomposed with an alkali for treatment.

[0002]

2. Description of the Related Art Hard-to-decompose halogen compounds represented by PCBs and the like are known as environmental pollutants, and several treatment methods for detoxifying the compounds have been proposed. Above all, a chemical decomposition treatment method using an alkali metal dispersion has received the most attention because it can be treated safely and reliably.

[0003] Conventionally, as a method for decomposing such a hardly decomposable halogen compound, for example, there is a method of heat-treating environmental pollutants such as PCBs or an organic solvent solution containing PCBs together with alkali metals in a dispersed state. Processing method (JP-A-49-82570)
Japanese Patent Application Laid-Open (JP-A) No. 6-181, and a method for dehalogenating a hardly decomposable halogen compound by reacting a hardly decomposable halogen compound dissolved in a hydrocarbon-based oil with molten sodium particles in a temperature range of 100 to 160 ° C. JP-A-59-20179), a method for treating a biphenyl chloride composition by reacting the biphenyl chloride composition with an alkali metal under heating conditions (see Canadian Patent No. 1142551), dispersion of a halogen compound and an alkali metal in an organic solvent. A method for decomposing a halogen compound by adding an active hydrogen compound which is not mixed with the organic compound to react with the compound (JP-A-9-21)
No. 6838), and the like.

[0004]

In the above-mentioned conventional method for decomposing a hardly decomposable halogen compound, in order to carry out the reaction more safely, a reaction vessel which can be shut off from the outside air is used. Usually, a hardly decomposable halogen compound to be decomposed and an alkali metal or the like are charged, and the reaction is usually carried out after replacing the inside with an inert gas.

However, depending on the method of replacing the inert gas and the purity of the inert gas, the decomposition time of the hardly decomposable halogen compound may vary, or the hardly decomposable halogen compound may not be completely decomposed. It was.

The present invention has been made in view of the above circumstances, and a method for dehalogenating and decomposing a hardly decomposable halogen compound with an alkali has been described. It is an object of the present invention to provide a method for decomposing a hardly decomposable halogen compound, which is capable of detoxifying the compound.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the decomposition time of the hardly decomposable halogen compound has been varied, and the hardly decomposable halogen compound has been completely removed. When not decomposed, it was found that the oxygen concentration in the space portion of the reaction vessel (the remaining space portion where the reactants, the solvent, and the like were added in the reaction vessel) was high. Therefore, by controlling the oxygen concentration in the space of the reaction vessel to be lower than the predetermined concentration or controlling the oxygen concentration to the predetermined concentration to perform the dehalogenation reaction of the hardly decomposable halogen compound, the reproducible and stable hardly decomposable compound can be obtained. The present inventors have found that detoxification of a halogen compound can be realized, and have completed the present invention.

That is, the present invention relates to a method for decomposing a hardly decomposable halogen compound by subjecting the hardly decomposable halogen compound to a dehalogenation reaction using an alkali, wherein the oxygen concentration in the reaction system is less than 3% by volume. Provided is a method for decomposing a hardly decomposable halogen compound, which comprises performing a dehalogenation reaction of the decomposable halogen compound.

The preferred embodiments of the present invention are as follows. (1) A method for decomposing a hardly decomposable halogen compound by dehalogenating a hardly decomposable halogen compound using an alkali in a reaction vessel which can be shielded from the outside air, wherein the oxygen concentration in the space of the reaction vessel is reduced. A dehalogenation reaction of the hardly decomposable halogen compound is performed while maintaining the content at less than 3% by volume. (2) A dehalogenation reaction of a hardly decomposable halogen compound is performed in an inert gas atmosphere having an oxygen content of 1% by volume or less. (3) In the above (1) or (2), the dehalogenating reaction of the hardly decomposable halogen compound is performed while maintaining the oxygen concentration in the space of the reaction vessel at 1% by volume or less. (4) In the above (1) to (3), an alkali metal dispersion is used as the alkali.

(5) Decomposition treatment of a hardly decomposable halogen compound by adding an activator to a mixture of a hardly decomposable halogen compound and an alkali metal dispersion in a reaction vessel capable of shutting off outside air to perform a dehalogenation reaction A method of providing an oxygen concentration in the space of the reaction vessel of less than 3% by volume and adding an activator. (6) A method for decomposing a hardly decomposable halogen compound in which a deactivating reaction is performed by adding an activator to a mixture of a hardly decomposable halogen compound and an alkali metal dispersion in a reaction vessel capable of shutting off outside air. The dehalogenation reaction is performed while maintaining the oxygen concentration in the space of the reaction vessel at less than 3% by volume. (7) In the above (5) or (6), the dehalogenation reaction is performed while maintaining the oxygen concentration in the space of the reaction vessel at 1% by volume or less. (8) In the above (5) to (7), the residual amount of the hardly decomposable halogen compound in the reaction mixture after the completion of the addition of the activator is 1 ppm or less.

According to the present invention, in the method of dehalogenating and decomposing with an alkali metal dispersion, it is possible to stably render the hardly decomposable halogen compound more reproducible and stable than the conventional method. Further, according to the present invention, complete dehalogenation / decomposition treatment of a halogen compound can be performed in a shorter time than in the past by simply maintaining the oxygen concentration in the space of the reaction vessel as low as possible.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The hardly decomposable halogen compound to be decomposed in the present invention is
Generally, it is an organic halogen compound which is difficult to dehalogenate. Examples of such hardly decomposable halogen compounds include aromatic halogen compounds such as PCB, dioxins, polychlorinated benzofurans, polychlorinated benzene, and DDT; and alicyclic halogen compounds such as BHC. INDUSTRIAL APPLICABILITY The present invention is suitable for an aromatic halogen compound contained in waste such as PCB.

The present invention can also be applied to the case where a hardly decomposable halogen compound dissolved in an organic solvent is decomposed. Examples of such an organic solvent include kerosene, decalin, electric insulating oil (electric insulating oil described in JIS C2320-1993), heavy oil (heavy oil described in JIS K2205), lubricating oil, and mixtures thereof. The present invention is particularly suitable for a case where a hardly decomposable halogen compound contained in an electric insulating oil is reacted with an alkali metal dispersion to perform a dehalogenation treatment.

Examples of the alkali used include alkali metals, alkali metal hydroxides, organic alkali metals, alkali metal carbonates, alkaline earth metals, alkaline earth metal hydroxides, organic alkaline earth metals, and alkaline earth metals. Carbonates and the like. These can be used alone or in combination of two or more.

Among these, in the present invention, it is preferable to use an alkali metal or an alkaline earth metal. As the alkali metal, for example, sodium, potassium,
Examples include lithium, cesium, and alloys thereof.
Examples of the alkaline earth metal include magnesium, calcium, and alloys thereof. In the present invention, among these alkali metals or alkaline earth metals, it is more preferable to use an alkali metal dispersion. As the alkali metal dispersion, one obtained by dispersing an alkali metal in a solvent can be used, and a metal sodium dispersion is particularly preferable.

As the solvent used for dispersing the alkali metal, for example, kerosene, decalin, electric insulating oil (JI
Electrical insulating oil described in SC2320-1993), heavy oil (heavy oil described in JIS K2205), and a mixture thereof, and preferably an electrical insulating oil described in JISC2320-1993.

The alkali metal concentration in the alkali metal dispersion is not particularly limited, but is preferably in the range of 5 to 50% by volume. Further, from the viewpoints of storability, transportability, redispersibility, decomposition treatment ability for halogen compounds, and the like, it is preferable that 80% or more of the alkali metal is alkali metal fine particles having a particle size of 30 μm or less, preferably 15 μm or less. .

Such an alkali metal dispersion can be prepared by a known method, for example, Inorganic Synthesis.
s. , Vol. 5, p6-10, "Sodium Di
methods described in “spersions”, and JP-A-10-1
It can be prepared by a method using a homogenizer described in No. 10205, and the like.

The amount of the alkali used for the reaction with the hardly decomposable halogen compound is usually 1 to 50 mol, in terms of the amount of the alkali contained in 1 mol of the halogen atom contained in the halogen compound. Preferably 1.05-2
It is in the range of 0 mol.

When reacting a hardly decomposable halogen compound with an alkali metal dispersion, it is preferable to coexist an active hydrogen compound such as water or a lower alcohol. The amount of the active hydrogen compound used is usually 2 mol or less, preferably 0.1 to 1.5 mol, per 1 mol of the alkali metal in the alkali metal dispersion.

The method of decomposing a hardly decomposable halogen compound by reacting it with an alkali is not particularly limited. For example, when an alkali metal dispersion is used as the alkali and water is used as the activator, a method of adding a predetermined amount of water to a mixture of the alkali metal dispersion and the hardly decomposable halogen compound, After mixing an organic solvent containing the compound with a predetermined amount of water, a method of adding an alkali metal dispersion and the like can be employed. In the case of the method described above, since the reaction between the alkali metal and water is intense, it is necessary to slowly add water little by little with sufficient stirring of the alkali metal dispersion in order to carry out the operation safely. Also,
Even in the case of the method, in order to safely perform the decomposition treatment, while sufficiently stirring a mixture of the organic solvent solution of the hardly decomposable halogen compound and a predetermined amount of water, the alkali metal dispersion is added little by little or several times. It is preferable to add them separately.

The reaction temperature between the hardly decomposable halogen compound and the alkali is usually from 0 to 300 ° C., preferably from room temperature to 200 ° C.
° C, more preferably in the range of room temperature to 100 ° C. The reaction time depends on the type and amount of the hardly decomposable halogen compound, but is usually 0.5 to 3 hours.

The present invention provides a method for decomposing a hardly decomposable halogen compound by reacting the hardly decomposable halogen compound with an alkali, wherein the oxygen concentration in the reaction system for reacting the hardly decomposable halogen compound with the alkali is less than 3% by volume. Preferably, the content is 1% by volume or less, more preferably 0.1% by weight or less.

As a method for reducing the oxygen concentration in the reaction system to less than 3% by volume, for example, before the dehalogenation reaction of the hardly decomposable halogen compound using a reaction vessel which can be shielded from the outside air or can be sealed. Another method is to completely replace the gas in the reaction vessel with an inert gas. The inert gas has an oxygen content of less than 3% by volume, preferably an oxygen content of 1% by volume or less, more preferably an oxygen content of 0.1% by volume or less.
Use those having a capacity of not more than%. Specific examples of the inert gas include nitrogen, helium, argon and the like.

The material, shape and capacity (size) of the reaction vessel used herein are not limited as long as it can be used for the reaction between the hardly decomposable halogen compound and the alkali. A reaction vessel that can be shut off is preferable, and a structure that can introduce an inert gas and exhaust the gas in the reaction vessel is more preferable.

When the space in the reaction vessel is replaced with an inert gas, the reaction vessel may be replaced with an inert gas depending on the size of the space in the reaction vessel, the purity of the inert gas, the flow rate of the inert gas, and the like before the start of the reaction. It is necessary to replace the gas in the space with an inert gas so that the oxygen concentration in the space of the reaction vessel is less than (or less than) a predetermined value.

According to the present invention, after the oxygen concentration in the reaction vessel is reduced to a predetermined concentration or less, the reaction can be carried out in a sealed state to carry out a dehalogenation reaction. Less than 3% by volume, preferably 1% by volume
It is preferable to carry out the reaction while maintaining the content at 0.1% by volume or less, more preferably. As a method for maintaining the oxygen concentration below a predetermined value, for example, a method in which the supply of an inert gas into the reaction vessel is continued until the end of the reaction while appropriately adjusting the flow rate using a flow meter or the like. According to this method, during the reaction, the oxygen concentration in the space of the reaction vessel can be easily and reliably maintained at a certain value or less.

In a particularly preferred embodiment of the present invention, a hardly decomposable halogen compound is placed in a reaction vessel capable of shutting off outside air, and the gas in the vessel is completely replaced with an inert gas having an oxygen content of 1% by volume or less. Thereafter, the mixture is heated to a predetermined temperature, an alkali metal dispersion is added under an inert gas atmosphere, and a predetermined amount of an activator is slowly added. According to this method, the oxygen concentration in the reaction system is easily and reliably reduced to less than 3% by volume, preferably 1% by volume or less, more preferably 0.01% by volume without making a significant change to the conventional decomposition treatment process. % Or less, and stable and prompt decomposition treatment of the hardly decomposable halogen compound is realized.

In the present invention, when an activator is added, the oxygen concentration in the reaction system is less than a predetermined value (or below) before the activator addition step, preferably during the period from the start to the end of the addition. ) Allows the dehalogenation reaction of the hardly decomposable halogen compound to proceed more quickly. The residual amount of the hardly decomposable halogen compound in the reaction mixture at the end of the addition of the activator is usually 1 ppm or less, preferably 0.8 ppm or less.

After completion of the reaction, it is usually preferable to add a large amount of water to the reaction mixture to decompose the unreacted alkali. When a reaction solvent is used, an organic solvent such as trans oil recovered by separating the reaction solution can be reused as a fuel or the like.

[0031]

The present invention will be described below in more detail with reference to Examples and Comparative Examples. The present invention is not limited to the following examples, and can be applied to any method for decomposing a hardly decomposable halogen compound by reacting a hardly decomposable halogen compound with an alkali in an organic solvent. In the following Examples and Comparative Examples, a 10% by volume metal sodium dispersion (hereinafter, referred to as “10”) obtained by dispersing metal sodium having a particle diameter of several microns in an electric insulating oil (manufactured by Idemitsu Kosan Co., Ltd.). % SD ").

(Example 1) 262.1 g of PCB-contaminated oil (PCB concentration: 37.15 p
pm), a stirring blade and a thermometer were attached, and nitrogen gas having a purity of 99.999% by volume was flowed into the four-necked flask with a flow meter KG-1 ( manufactured by Kusano Scientific Instruments Co., Ltd .; the same applies hereinafter). The temperature was raised to 65 ° C. over 40 minutes while the inside of the reaction system was purged with nitrogen by flowing at a scale of 100 (0.264 L / min). Thereafter, the flow rate of the nitrogen gas was measured by the flow meter KG-1.
5 scales (0.0009 L / min) and 10% S
After adding 3.48 g of D and stirring at 65 ° C. for 30 minutes, 3.23 g of 10% SD was further added. Thereafter, 0.24 ml of water was immediately added as an activator over 60 minutes,
The reaction was further performed at 65 ° C. for 60 minutes. PC in reaction mixture
The analysis of B concentration was performed 30 days after the completion of the second addition of 10% SD.
Went after a minute. As a result, the PCB concentration was below the detection limit (0.5 ppm or less, the same applies hereinafter).

Example 2 In a 500 ml four-necked flask, 254.4 g of PCB-contaminated oil (PCB concentration: 37.15 p
pm), a stirring blade and a thermometer were attached, and nitrogen gas having a purity of 99% by volume (oxygen content: 1% by volume) was supplied to a flow meter KG-
The temperature was raised to 65 ° C. over 40 minutes while flowing at 100 graduations (0.264 L / min) and replacing with nitrogen. Thereafter, the flow rate of the nitrogen gas was set to 5 divisions (0.0009 L / min) by the flow meter KG-1, and 10% SD was 3.7.
After adding 0 g and stirring at 65 ° C. for 30 minutes, 2.70 was added.
g of 10% SD was added. Thereafter, 0.24 ml of water was immediately added as an activator over 60 minutes.
For 60 minutes. Analysis of the PCB concentration in the reaction mixture was performed 30 minutes after the completion of the second addition of 10% SD. As a result, the concentration of residual PCB after 30 minutes was below the detection limit.

Example 3 In a 500 ml four-necked flask, 262.1 g of PCB-contaminated oil (PCB concentration: 37.15)
ppm), and a stirring blade and a thermometer were attached.
9.99% nitrogen gas was flown at 5 scales (0.009 L / min) with a flow meter KG-1 while purging with nitrogen.
The temperature was raised to 65 ° C. over 40 minutes. After that, nitrogen gas was flowed through the flow meter KG-1 at 5 scales (0.0009 L / min).
3.51 g of 10% SD was added while flowing at 65 ° C.
After stirring for 30 minutes, 2.84 g of 10% SD was further added. Then immediately 0.24 ml of water as activator
Was added over 60 minutes, and further reacted at 65 ° C. for 60 minutes. Analysis of the PCB concentration of the reaction mixture was performed for the second 10%
After completion of the addition of SD, the test was performed at the lapse of 30 minutes and 60 minutes. As a result, the residual PCB concentration after 30 minutes was 16.
It was 74 ppm, and the residual PCB concentration after 60 minutes was below the detection limit.

Comparative Example 1 In a 500 ml four-necked flask, 263.5 g of PCB-contaminated oil (PCB concentration: 37.15)
ppm), and a stirring blade and a thermometer were attached.
7% by volume nitrogen gas (oxygen content 3% by volume)
The temperature in the reaction system was raised to 65 ° C. over 40 minutes while the inside of the reaction system was purged with nitrogen by flowing at 100 scales (0.264 L / min) at G-1. Thereafter, the flow rate of the nitrogen gas was measured by the flow meter KG-1.
5 scales (0.0009 L / min) and 10% S
After adding 3.72 g of D and stirring at 65 ° C. for 30 minutes, 2.71 g of 10% SD was further added. Thereafter, 0.24 ml of water was immediately added as an activator over 60 minutes,
The reaction was further performed at 65 ° C. for 60 minutes. PC in reaction mixture
The analysis of B concentration was performed 30 days after the completion of the second addition of 10% SD.
Minutes, 60 minutes and 120 minutes later. As a result, 3
The residual PCB concentration after 0 minutes was 21.24 ppm, the residual PCB concentration after 60 minutes was 0.77 ppm, and the residual PCB concentration after 120 minutes was below the detection limit.

Comparative Example 2 261.1 g of PCB-contaminated oil (PCB concentration: 37.15 p
pm), and a stirring blade and a thermometer were attached.
While flowing 999% by volume of nitrogen gas and purging with nitrogen, 13
The temperature was raised to 65 ° C over a minute. At that time, the oxygen concentration in the space of the four-necked flask was 3.2% by volume. Next, 2.34 g of 10% SD was added, and the mixture was stirred at 65 ° C. for 30 minutes, and then 4.47 g of 10% SD was further added. Immediately thereafter, 0.24 ml of water was added as an activator over 60 minutes, and further reacted at 65 ° C. for 120 minutes. The analysis of the PCB concentration of the reaction mixture was performed after the completion of the second addition of 10% SD, 60 minutes, 120 minutes, and 180 minutes. As a result, after 60 minutes, the residual P
The CB concentration was 4.07 ppm, the residual PCB concentration was 0.53 ppm after 120 minutes, and the residual PCB concentration was below the detection limit after 180 minutes.

Comparative Example 3 PC was placed in a 1 L four-necked flask.
261.9 g of B-contaminated oil (PCB concentration 37.15 ppm)
Take a stirrer and a thermometer, and purify 99.999
Nitrogen was purged by flowing a volume% nitrogen gas. The oxygen concentration in the space at that time was 4% by volume. Thereafter, the inside of the four-necked flask was shut off from the outside air, and the temperature was raised to 65 ° C. and 10%
After adding 2.97 g of SD and stirring at 65 ° C. for 30 minutes,
An additional 3.14 g of 10% SD was added. Thereafter, 0.24 ml of water was immediately added as an activator over 60 minutes, and further reacted at 65 ° C. for 120 minutes. Analysis of the PCB concentration of the reaction mixture was performed after the completion of the second 10% SD addition.
The test was performed when 60 minutes and 180 minutes had elapsed. as a result,
The residual PCB concentration after 60 minutes was 17.99 ppm, and the residual PCB concentration after 180 minutes was 16.35 pp.
m.

Example 1 is an example in which the reaction was carried out by continuously flowing nitrogen gas having a purity of 99.999% by volume into the reaction vessel, and Example 2 was conducted by flowing nitrogen gas having a purity of 99% by volume into the reaction vessel. Example 3 is an example in which the reaction was continued, and Example 3 was an example in which the reaction was performed in the same manner as in Example 1 except that the flow rate of nitrogen gas having a purity of 99.999% by volume was reduced. In each case, the decomposition of the PCB was complete within 60 minutes.

On the other hand, Comparative Example 1 is an example in which the reaction was performed at an oxygen concentration of 3% by volume, Comparative Example 2 was an example in which the reaction was performed at an oxygen concentration of 3.2%, and Comparative Example 3 was an example in which the reaction was performed at an oxygen concentration of 4%. %. In Comparative Example 1, it took 120 minutes to decompose the PCB. In Comparative Examples 2 and 3, the replacement was performed with nitrogen gas having a purity of 99.999% by volume, but the replacement was insufficient.
It took 180 minutes to decompose B, and in Comparative Example 3, the PCB was not completely decomposed.

[0040]

As described above, according to the present invention,
In a method of dehalogenating and decomposing with an alkali metal dispersion, a method for decomposing a hardly decomposable halogen compound which can stably render the hardly decomposable halogen compound harmless with higher reproducibility than conventional methods is provided. Further, according to the present invention, complete dehalogenation / decomposition treatment of a halogen compound can be performed in a shorter time than in the past by simply maintaining the oxygen concentration in the space of the reaction vessel as low as possible.

Claims (10)

[Claims] 1. A method for decomposing a hardly decomposable halogen compound by subjecting the hardly decomposable halogen compound to a dehalogenation reaction using an alkali, wherein the oxygen concentration in the reaction system is less than 3% by volume. A method for decomposing a hardly decomposable halogen compound, comprising subjecting the compound to a dehalogenation reaction. 2. The method for decomposing a hardly decomposable halogen compound according to claim 1, wherein the dehalogenating reaction of the hardly decomposable halogen compound is performed by setting the oxygen concentration in the reaction system to 1% by volume or less. 3. A method for decomposing a hardly decomposable halogen compound by subjecting the hardly decomposable halogen compound to a dehalogenation reaction using an alkali, wherein the hardly decomposable halogen compound is decomposed in an inert gas atmosphere having an oxygen content of 1% by volume or less. The method for decomposing a hardly decomposable halogen compound according to claim 1 or 2, wherein a dehalogenation reaction of the non-decomposable halogen compound is performed. 4. A method for decomposing a hardly decomposable halogen compound, which comprises subjecting the hardly decomposable halogen compound to a dehalogenation reaction using an alkali in a reaction vessel that can be shielded from outside air,
The method for decomposing a hardly decomposable halogen compound according to claim 1, wherein the dehalogenating reaction of the hardly decomposable halogen compound is performed while maintaining the oxygen concentration in the space of the reaction vessel at less than 3% by volume. 5. The hardly decomposable halogen according to claim 1, wherein the dehalogenating reaction of the hardly decomposable halogen compound is performed while maintaining the oxygen concentration in the space of the reaction vessel at 1% by volume or less. Compound decomposition method. 6. The method according to claim 1, wherein an alkali metal dispersion is used as said alkali. 7. The method according to claim 1, further comprising a step of adding an activator to the mixture of the hardly decomposable halogen compound and the alkali metal dispersion in a reaction vessel capable of shutting off the outside air. Method for decomposing a reactive halogen compound. 8. A method for decomposing a hardly decomposable halogen compound, wherein an activator is added to a mixture of a hardly decomposable halogen compound and an alkali metal dispersion in a reaction vessel which can be shielded from the outside air to carry out a dehalogenation reaction. A method for decomposing a hardly decomposable halogen compound, comprising the step of adding an activator while maintaining the oxygen concentration in the space of the reaction vessel at less than 3% by volume. 9. The method for decomposing a hardly decomposable halogen compound according to claim 8, further comprising the step of adding an activating agent while maintaining the oxygen concentration in the space of the reaction vessel at less than 1% by volume. 10. After the completion of the addition of the activator, the residual amount of the hardly decomposable halogen compound in the reaction mixture is 1 ppm.
The method for decomposing a hardly decomposable halogen compound according to any one of claims 7 to 9, wherein: