JPH0854325A - Method and device for sampling gas for thermal analysis - Google Patents

Abstract

PURPOSE:To provide a method and device for sampling gas for thermal analysis by which gas sampling can be always performed with a high efficiency at a desired effective timing. CONSTITUTION:During the course of TG-DTA analysis at a TG-DTA section 1, the gas discharged from a sample 12b in a sample chamber 12 is collected by adsorption into the gas adsorbing tubes 21a, 21b, 21c, and 21d of a gas sampling section 2 through a gas collecting tube 4 by sucking the gas by means of a rotary pump 25. The gas collecting timing of each tube 21a, 21b, 21c, and 21d is controlled by opening a solenoid valve 22a, 22b, 22c, or 22d by means of a central controller which detects the state where the temperature of the sample 12b becomes a specific value, when the differential thermal change becomes a specific state, or the amount decreasing rate becomes a specific value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention samples a gas released from a sample in a thermal analysis process such as a differential thermal analysis or a thermogravimetric analysis for measuring a thermal change of the sample which occurs when the temperature of the sample is changed. Gas sampling method and apparatus for thermal analysis.

[0002]

2. Description of the Related Art Conventionally, a differential thermal analysis method in which a sample and a standard sample are heated and cooled at a constant temperature rising and cooling rate to measure a differential heat which is a temperature difference between the two, or a method which depends on the temperature of the sample Thermal analysis methods such as a thermogravimetric analysis method for measuring a thermogravimetric change which is a change in weight due to a change in weight are known.

In the process of thermal change in the process of thermal analysis, for example, in the process of thermal change such as endothermic or exothermic in the case of differential thermal analysis, or in the process of thermal change such as thermogravimetric change in the case of thermogravimetric analysis. In many cases, gas is generated from the sample. Especially when there is a thermogravimetric change, some gas is always generated. Also in the differential thermal analysis, in the case of an endothermic reaction due to dehydration or decomposition, or in the case of an exothermic reaction due to combustion, a gas is generated together with a change in thermogravimetric change.

In order to measure such a thermal change in more detail, a gas sampling device which samples the gas generated in the process of the thermal change and enables component analysis by a gas chromatograph device, a mass spectrometer or the like. Has been proposed in the past.

The conventional gas sampling apparatus according to this proposal starts sampling at regular time intervals at the same time when the thermal analysis measurement is started.

[0006]

However, in the method of starting sampling at a constant time interval at the same time when the thermal analysis measurement is started, the sampling is performed uniformly even when the gas is not generated. For this reason, it is possible to check the presence or absence of gas generation for each sampling, but for example, the gas sampled for each sampling should be collected in a separate container, and the gas collected in that container later should be analyzed by the gas chromatograph. There is a risk that desired sampling may not be possible in the case of analysis using a tograph device or the like. In other words, if you try to secure the required number of sampling points while the gas from the sample is being generated, the number of sampling points will often be enormous in the entire measurement, and along with this, prepare for gas sampling. In many cases, the number of containers to be used becomes huge and becomes unrealistic.

Therefore, for example, a method may be considered in which the sampling start time point is shifted from the thermal analysis start time point and set immediately before the thermal change is started. However, for an unknown sample whose thermal change is unknown, The measurement cannot be performed unless preliminary measurement is performed in advance and the time point at which the thermal change occurs is checked. However, since thermal analysis is a so-called destructive test, preliminary measurement may be difficult when the unknown sample is valuable. In addition, since the time when the thermal change occurs depends on the heating rate, even if preliminary measurement is performed at a certain heating rate, it is not possible to accurately specify the time when the thermal change occurs at a heating rate different from this. It is often difficult.
Therefore, there may be a case where preliminary measurement must be performed for each heating rate.

As described above, in the conventional gas sampling method for designating the time, there are many cases where desired sampling cannot be performed.

The present invention has been made under the background described above, and an object of the present invention is to provide a gas sampling method in thermal analysis and an apparatus therefor, which can always perform gas sampling efficiently at a desired and effective timing. It is what

[0010]

In order to solve the above-mentioned problems, the gas sampling method in the thermal analysis according to the present invention is (Structure 1): the thermal change of the sample caused when the temperature of the sample is changed. In a gas sampling method in a thermal analysis for sampling a gas released from a sample in a thermal analysis process for measurement, the gas sampling is performed when the temperature of the sample reaches a specific temperature of 1 or 2 or more. And a configuration characterized by
(Structure 2) In the gas sampling method in the thermal analysis for sampling the gas released from the sample in the thermal analysis process for measuring the thermal change of the sample that occurs when the temperature of the sample is changed, the gas sampling is performed by the thermal analysis. The configuration is characterized in that it is carried out when the thermal change of the sample in 1) becomes a specific one or two or more states. As an aspect of the above-mentioned configuration 2, (configuration 3) gas in the thermal analysis of configuration 2 In the sampling method, the thermal analysis is a thermogravimetric analysis for measuring a weight change of the sample, and the thermal change is a physical quantity depending on the thermogravimetric change of the sample. (Configuration 4) In the gas sampling method for thermal analysis according to any one of Configurations 1 to 3, the gas sampling is The gas released from the sample is introduced into each of one or more gas adsorption tubes filled with a substance that once adsorbs and holds the adsorbed gas, but releases the adsorbed gas again by performing a certain process. The configuration is characterized by the above.

Further, the gas sampling apparatus in the thermal analysis according to the present invention is (Structure 5): A sample chamber capable of taking out the gas released from the sample to the outside, and a temperature control means for controlling the temperature of the sample in the sample chamber. And a thermal analysis device having a thermal change measuring means for measuring the thermal change of the sample,
A gas adsorption tube having a gas introduction end connectable to a sample chamber of the thermal analysis apparatus, which is filled with a substance that adsorbs and holds a gas but releases it again by heat treatment.
Alternatively, two or more gas adsorption pipes, a suction device having a suction side connectable to the end of the gas adsorption pipe opposite to the gas introduction end, and a flow path between the gas adsorption pipe and the suction device. An electromagnetic valve device that is provided to control the opening and closing of the suction and a control device that respectively detects that the thermal change of the sample has reached one or more specific states and controls the opening and closing of the electromagnetic valve device. A configuration characterized by being provided, and as an aspect of this configuration 5, (configuration 6), in the gas sampling device in the thermal analysis of configuration 5, the thermal analysis device is a thermobalance device for measuring a thermogravimetric change of the sample. The thermal change is a thermogravimetric change of the sample.

[0012]

In the above-mentioned structure 1, the gas sampling is performed when the temperature of the sample reaches a specific temperature of 1 or 2. That is, in other words, the gas sampling timing is specified by temperature rather than time. According to this, it becomes possible to easily secure the required number of sampling points while the gas from the sample is generated, as compared with the conventional case in which the timing of gas sampling is designated by time. That is, in the thermal analysis process, it is difficult to accurately specify in advance the time at which the thermal change accompanied by gas generation occurs, but the temperature at which the thermal change occurs can be specified relatively accurately. Is.

Further, according to the configuration 2, it becomes possible to more reliably ensure the required number of sampling points while the gas from the sample is being generated. Moreover, in this case, it is possible to perform sampling at an optimum timing substantially according to the situation of gas generation. That is, since there is a close relationship between the generation of gas and the thermal change of the sample, for example,
By detecting that the thermal change of the sample, such as differential thermal change or thermogravimetric change, has reached a predetermined state and sampling is performed in that state, it is possible to reliably perform the desired sampling. .

Structure 3 is a case where the thermal analysis is thermogravimetric analysis for measuring the weight change of the sample, and the thermal change is a physical quantity depending on the thermogravimetric change of the sample. Since the thermogravimetric change, which is a thermal change in thermogravimetric analysis, has a particularly close relationship with gas generation, this thermogravimetric change has a specific state, for example, a weight loss rate of 1%, 3%, 10%. By sampling when a specific value is reached, such as, it becomes possible to perform efficient gas sampling with a small number of sampling points, and even if preliminary measurement is performed on unknown samples. It is possible to perform reliable sampling without missing the timing of gas generation.

According to the configuration 4, the gas at each sampling time is stored in each adsorption tube, and after completion of the thermal analysis measurement,
By subjecting each adsorption tube to a certain treatment such as heating to release the adsorbed gas, the adsorption tube can be used for analysis of a gas chromatograph or the like.

According to the configurations 5 and 6, it is possible to obtain an apparatus capable of implementing the method of the configurations 1 to 4.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing the configuration of a gas sampling apparatus for thermal analysis according to an embodiment of the present invention. Hereinafter, a thermal analysis method and apparatus according to an embodiment will be described with reference to FIG.

In FIG. 1, reference numeral 1 is a thermogravimetric / differential thermal analyzer (TG-DTA) unit constituting a thermal analyzer, reference numeral 2 is a gas sampling device portion, and reference numeral 3 is a central control unit. In short, this device is for sampling the gas generated from the sample at the time of TG-DTA measurement in the TG-DTA section 1 into the adsorption tube built in the gas sampling section 2.

The TG-DTA section 1 is a balance chamber section 11, and a sample chamber section 1 provided above one end of the balance chamber section 11.
2. It is composed of a heating furnace 13 for heating the sample chamber 12.

The balance chamber section 11 includes a balance chamber 11a, a support 11b standing upright in the balance chamber 11a, and a support 11b.
It is composed of a balance 11c supported by b.

The balance 11c includes a balance rod 11d, a fulcrum 11e provided at the center of the balance rod 11d, and the balance rod 1
It has weights 11f and 11f suspended at both ends of 1e.
Further, the weight 11f suspended at one end of the balance rod 11e, that is, the right end in the figure, has its lower end rotatably supported at the end of the balance rod 11e on which this weight 11f is suspended, and is vertically supported. Weight is applied to the lower end of the upright supporting rod 11g. That is, the support rod 11g is rotatably and vertically erected on one end of the balance rod 11d by the weight of the weight 11f.

The support rod 11g is provided upright toward the sample chamber portion 12 through a through hole 11h provided in the upper portion of the balance chamber 11a, and a differential heat detecting portion 12a is provided at the upper end portion thereof.

The differential heat detecting section 12a is provided with a sample placing section and a standard sample placing section for placing the sample 12b and the standard sample 12c, respectively, and the temperature of a thermocouple or the like for detecting the temperature difference between them. Detection means and the like are provided.

That is, the TG-DTA unit 1 detects the weight change of the sample 12b by the balance 11c, and at the same time, detects the differential heat by the differential heat detection unit 12a. In addition,
The balance 11c is provided with a tilt detecting means and a weight change detecting means incorporated in the fulcrum portion 11e for correcting the tilt by a tilt correcting means using an electromagnetic coil and a magnet, and detecting a weight change from a current required at that time. I have it. The differential heat detection unit 12a is connected to the fulcrum portion 11e through the support rod 11g and the balance rod 11d. From the fulcrum portion 11e, the weight change detecting means is connected to the connector 11j by a flexible conductor, and the TG-DTA circuit 15 is connected. It has become so.

Further, the differential heat detection part 12a is housed in a gas flow protection tube 12d, and the portion where the differential heat detection part 12a is provided in the gas flow protection tube 12d is the sample chamber. The part 12 is configured. The sample chamber 12 is installed in the heating furnace 13. This heating furnace 13 is a sample 12
The temperature of b is controlled by the temperature controller 16.

The gas flow protection tube 12d is made of quartz glass and has a substantially cylindrical shape. Both upper and lower ends are open ends, but the upper open end is formed to have a small diameter. The lower open end is fitted and supported in a sealed state in a protective tube support hole 11i provided above one end of the balance chamber 11a via an O-ring or the like.

Further, the lower end portion of the branch connecting fitting 14 is fitted to the outer peripheral portion of the upper open end of the gas flow protection tube 12d. The branch connection fitting 14 has a cylindrical shape of which both ends are opened, the inner diameter of which is substantially equal to the outer diameter of the upper open end of the gas flow protection tube 12d, and the branch port 1 is provided on the side thereof.
4a, the lower end is fitted to the upper open end of the gas flow protection tube 12d, the leading end of the gas sampling tube 4 is fitted to the upper end, and the branch port 14a is further fitted with gas. The discharge pipe 14b is connected. During the thermal analysis measurement, the flow gas inlet 11k provided at the rear end of the balance chamber 11 is connected to the pipe 11l in the gas flow protection tube 12d.
A flow gas supplied from a flow gas source such as an inert gas (not shown) is constantly flowed through and is discharged to the outside through the branch port 14a. As a result, only the new gas generated from the sample 12b always reaches the tip of the gas sampling tube 4, and the gas generated in the past is discharged to the outside so that the gas at each time of gas generation is discharged. It is possible to collect.

The gas sampling pipes 4 are four cavity tubes 4
The a, 4b, 4c, and 4d are bundled, and one end thereof is fixed to the plug body 4e. The plug 4e is hermetically inserted into the upper open end of the branch connection fitting 14. As a result, the tip of each capillary tube is located above the sample in the sample chamber 12, and the gas released from the sample 12b can be properly collected.

The gas sampling section 2 includes a gas adsorption tube 21 in which the rear ends of the respective capillary tubes 4a, 4b, 4c, 4d of the gas sampling tube 4 are connected to the gas inlet end.
a, 21b, 21c, 21d, and solenoid valves 22a, 22b connected to the gas outlet ends of these gas adsorption tubes, respectively.
22c, 22d, a solenoid valve control circuit 26 for controlling the opening and closing of these solenoid valves, a filter 23 having a built-in activated carbon or the like in which all the gas outlets of these solenoid valves are connected to the gas inlet, and this filter 23. It has a mass flow controller 24 connected to the gas exhaust port and a rotary pump 25 for vacuum exhaust connected to the mass flow controller 24. That is, the rotary pump 2
When any one of the solenoid valves is opened while being sucked by 5, the gas generated from the sample 12b is introduced into the adsorption tube connected to the opened solenoid valve through the capillary tube.

Gas adsorption tubes 21a, 21b, 21c, 21
d is a substance that once adsorbs and holds a gas but releases it again by heat treatment (for example, Enka Research Instit
Some are sold by ute under the trade name Tenax).

The central controller 3 has a built-in information processing circuit such as a microprocessor, and sends and receives signals to and from the TG-DTA circuit 15, the temperature controller 16 and the solenoid valve control circuit 26 according to a predetermined program. Control of the TG-DTA analysis, and when the TG weight loss rate in the TG-DTA analysis reaches a specific value, for example, 0.5%, 1%, 3%, 10%. The solenoid valves 22a, 22b, 22c, 22d are sequentially opened, and the gas adsorption pipes 21a, 21b, 21c, 21d are controlled to collect the generated gas at each reduction rate.

According to one embodiment described above, the thermogravimetric change is
Since it has a particularly close relationship with gas generation, reliable sampling can be performed without missing the sampling timing. In addition, it is possible to perform efficient gas sampling with a small number of sampling points, and it is possible to perform reliable sampling of unknown samples without missing the timing of gas generation without preliminary measurement. Have the advantage of.

In the above-mentioned one embodiment, the case where the thermal analysis is thermogravimetric analysis is mentioned. However, this is not limited to other thermal analysis such as differential thermal analysis or differential scanning calorimeter. Good. Further, although the sampling is performed when the thermogravimetric change has a specific value, this may be performed, for example, when the sample temperature reaches a specific temperature.

[0034]

As described above in detail, the gas sampling method and apparatus in the thermal analysis according to the present invention performs gas sampling when the temperature of the sample reaches a specific temperature of 1 or 2 or This is to be performed when the thermal change of the sample in the thermal analysis reaches a specific one or more than two states, so that gas sampling can always be performed efficiently at a desired and effective timing. Is.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a gas sampling apparatus in thermal analysis according to an example of the present invention.

[Explanation of symbols]

1 ... TG-DTA section, 2 ... Gas sampling section, 3 ... Central control unit, 4 ... Gas sampling tube, 11 ... Balance chamber section, 12 ...
Sample chamber part, 12b ... Sample, 13 ... Heating furnace, 21a, 21
b, 21c, 21d ... Gas adsorption tubes, 22a, 22b, 2
2c, 22d ... Solenoid valve, 25 ... Rotary pump.

Claims (6)

[Claims] 1. A gas sampling method in thermal analysis for sampling a gas released from a sample in a thermal analysis process for measuring a thermal change of the sample that occurs when the temperature of the sample is changed. The specific temperature is 1 or 2
A gas sampling method in thermal analysis, characterized in that it is carried out when the above temperature is reached. 2. A gas sampling method in a thermal analysis for sampling a gas released from a sample in a thermal analysis process for measuring a thermal change of the sample that occurs when the temperature of the sample is changed. A gas sampling method in thermal analysis, characterized in that it is carried out when the thermal change of the sample in the analysis reaches one or more specific states. 3. The gas sampling method in thermal analysis according to claim 2, wherein the thermal analysis is thermogravimetric analysis for measuring a weight change of a sample, and the thermal change depends on a thermogravimetric change of the sample. A gas sampling method in thermal analysis characterized by being a physical quantity. 4. The gas sampling method for thermal analysis according to claim 1, wherein in the gas sampling, the gas is once adsorbed and held, but a certain process is performed to release the adsorbed and held gas again. A gas sampling method in thermal analysis, characterized in that the gas released from the sample is introduced into one or more gas adsorption tubes filled with the substance to be charged at each gas sampling. 5. A sample chamber which can take out gas emitted from the sample to the outside, temperature control means for controlling the temperature of the sample in the sample chamber, and thermal change measuring means for measuring the thermal change of the sample. A thermal analysis device and a gas adsorption tube whose gas introduction end can be connected to the sample chamber of the thermal analysis device, which is filled with a substance that once adsorbs and holds a gas but releases it again after a certain treatment. 1 or 2 or more gas adsorption tubes, a suction device capable of connecting a suction side to the end of the gas adsorption tube opposite to the gas introduction end, and a flow path between the gas adsorption tube and the suction device An electromagnetic valve device that is provided in the control unit to control the opening and closing of the suction; and a control device that detects the thermal change of the sample in one or more specific states and controls the opening and closing of the electromagnetic valve device. In thermal analysis characterized by having Gas sampling device. 6. The gas sampling device for thermal analysis according to claim 5, wherein the thermal analysis device is a thermobalance device for measuring a thermogravimetric change of the sample, and the thermal change is a thermogravimetric change of the sample. A gas sampling device in thermal analysis characterized by the above.