JP2010066095A - Method of rapidly evaluating adsorbing behavior of organic compound vapor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To rapidly evaluate the adsorbing behavior of an organic compound vapor to an adsorbent by applying gas chromatography. <P>SOLUTION: A column 3 filled with the adsorbent 4 to be evaluated is installed in a column tank 2 capable of being set to an optional temperature, the organic compound vapor is injected in the column 3 from this side of the inlet of the column 3 while allowing a carrier gas to flow through the column 3 and a chromatogram, which is obtained by detecting the organic compound vapor by the detector 5 installed behind the outlet of the column 3, is analyzed to rapidly evaluate the adsorbing behavior of the organic compound vapor. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a method for quickly and simply evaluating the adsorption behavior of organic compound vapors.

Volatile organic compounds (VOC) are widely used in the industry as cleaning agents, solvents or chemical raw materials, but in recent years, there is a strong concern about air pollution caused by these. VOC removal techniques include adsorption and combustion methods, but the combustion method is a method of discharging VOCs into the atmosphere as CO2, and is said to be consistent with environmental policies such as 3R promotion and greenhouse gas reduction. hard. VOC is originally a vaporized organic compound, that is, an organic compound vapor, and can be regarded as a valuable material that can be reused if it is properly recovered. Therefore, removal and recovery by an adsorption method has attracted attention.

In the technical development of the adsorption method, evaluation of the adsorption behavior of organic compound vapor is an important technical element. In an industrial adsorption removal process, usually only organic compound vapor is adsorbed and removed by ventilating exhaust gas containing organic compound vapor continuously in an adsorption tower filled with an adsorbent. In the development of adsorbents applied to such industrial processes, in order to evaluate the adsorption behavior, it was important to measure the adsorption breakthrough curve and grasp the amount of adsorption during breakthrough obtained therefrom. In order to measure the adsorption breakthrough curve, it is necessary to continuously generate the target organic compound vapor at a stable concentration, but with a vaporizer normally used to obtain the organic compound vapor, it is necessary to stabilize the concentration. Often, it takes about 1 to 2 hours. Furthermore, the measurement of the adsorption breakthrough curve takes several tens of minutes to several hours, and after the measurement, it is necessary to perform the desorption operation for several hours at a high temperature while venting inert gas through the adsorption tower. It was an evaluation method requiring an extremely long time, which required about 4 to 10 hours in total.

Now, as organic compound vapors handled in factories, etc., hydrocarbons such as pentane, carbonyl compounds such as methyl ethyl ketone, alcohols such as 2-propanol, halogenated hydrocarbons such as trichloroethylene, esters such as ethyl acetate, etc. It is said that there are hundreds of types. In order to evaluate the adsorption behavior of such a large number of organic compound vapors, it is difficult to say that it is efficient to measure the adsorption breakthrough curve.

Thus, as a method for evaluating the adsorption behavior of organic compound vapor, Patent Document 1 discloses a simple adsorption isotherm measurement method using a small amount of sample material. However, this method has a difficulty in evaluating the adsorption behavior in a situation where the sample substance is continuously introduced.

JP-A-5-34325

On the other hand, the development of chemical analysis equipment in recent years is remarkable, and gas chromatography is an analysis equipment for gas components at room temperature and relatively volatile components having a vapor pressure of about several Torr at the maximum temperature of the column. Has developed as much. In recent years, the performance has been improved not only in functional aspects such as higher sensitivity due to improved detector performance and better temperature control functions due to improved control technology, but also in convenience such as auto-sampling functions and temperature control programming. The improvement is remarkable.

That is, an object of the present invention is to provide a technique for quickly and easily evaluating the adsorption behavior of an organic compound vapor by applying gas chromatography in order to contribute to the development of an adsorbent that adsorbs the organic compound vapor. . In addition, improvement in measurement accuracy and convenience can be expected by effectively utilizing such elemental technologies of gas chromatography that are remarkably developed.

As a result of earnest research and development on the method for evaluating the adsorption behavior of organic compound vapor, the present inventor installed a column filled with the adsorbent to be evaluated in a column tank that can be set to an arbitrary temperature, and the carrier gas is placed in the column. Analyze the chromatogram obtained by injecting organic compound vapor from the front of the column while circulating it and detecting the organic vapor with a detector installed behind the column outlet, and compare it with the chromatogram of the reference substance. Thus, a method for quickly evaluating the adsorption behavior of the organic compound vapor was found, and the present invention was completed. (Here, the breakthrough adsorption amount Qbs and the equilibrium adsorption amount Qes of the reference substance are measured in advance.)

That is, the technical solution means of the present invention is: (1): a detector installed behind a column outlet by filling the column with an adsorbent, injecting an organic compound vapor from the front of the column while circulating the carrier gas through the column (2): The boiling point of the organic compound is −10 ° C. or more and 400 ° C. or less, which is characterized by analyzing the chromatogram obtained by detecting the organic compound vapor in (3): The method according to (1) or (2), wherein the adsorbent is activated carbon, silica gel, alumina or zeolite, 4): The method according to (1), (2) or (3), wherein the temperature of the column tank in which the column is installed is -10 ° C or higher and 450 ° C or lower. (5) From the retention index obtained by dividing the retention time of the obtained organic compound vapor by the retention time of the reference substance and calculating the common logarithm, the adsorption amount at breakthrough when using the organic compound vapor is the equilibrium adsorption amount. The method according to (1), (2), (3), or (4), wherein the adsorption ratio calculated by dividing is predicted.

According to the present invention, the adsorption behavior of an organic compound vapor can be evaluated quickly and easily without measuring an adsorption breakthrough curve that has been indispensable for evaluating the adsorption behavior. That is, the amount of adsorption Qbs during breakthrough and the equilibrium adsorption amount Qes of the reference material are measured in advance, the adsorption ratio Rs = Qbs / Qes of the reference material is calculated, and the retention index of the evaluation target organic compound vapor is determined by the method according to the present invention. By measuring with, it is possible to predict the adsorption ratio of the organic compound to be evaluated, which is convenient.

Hereinafter, the details of the present invention will be described in detail by way of examples. However, the present invention is intended to specifically describe the technical contents of the present invention and does not limit the scope of the present invention.

(Type of organic compound vapor)
The organic compound species that can evaluate the adsorption behavior are aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, carbonyl compounds, alcohols, esters, ethers, etc., and preferably have a boiling point of −10 ° C. or more and 400 It is a compound having a temperature of 20 ° C. or lower, more preferably 20 ° C. or higher and 260 ° C. or lower. It does not preclude that these organic compound molecules contain different atoms such as nitrogen, phosphorus, sulfur and halogen.

(Method of introducing organic compound vapor)
The organic compound can be introduced into the column as it is if it is gaseous. If it is liquid, it may be injected into a vaporization chamber installed in front of the column entrance, and then vaporized in a high temperature chamber and then introduced into the column. Further, the organic compound may be introduced alone into the column, or a plurality of types may be mixed and introduced.

(Reference substance)
As the reference substance, any substance can be used as long as it is an organic compound vapor. In particular, a substance having a molecular weight close to that of the substance to be evaluated and / or a homologous compound is more preferable.

(Adsorbent type)
Examples of the adsorbent for evaluating the adsorption behavior of the organic compound vapor include activated carbon, silica gel, alumina, zeolite, and the like, but are not necessarily limited to these adsorbents.

(Column tank)
The column filled with the adsorbent is installed in a column tank whose inside can be set to an arbitrary temperature. Since the chromatogram varies greatly depending on the column temperature, it is necessary to obtain chromatograms measured at the same column tank temperature in order to compare the reference substance and the organic compound vapor to be evaluated. The temperature range of the column tank when measuring the chromatogram is preferably −10 ° C. or higher and lower than 450 ° C., more preferably 20 ° C. or higher and lower than 300 ° C. It is also preferable that the column tank has a function of increasing the temperature at an arbitrary rate of temperature increase.

(Detector)
The detector installed behind the column outlet for detecting the organic compound vapor may be any detector that can measure the amount of the organic compound vapor, but may be a thermal conductivity detector (TCD). ), A flame ionization detector (FID), an electron capture detector (ECD), a mass spectrometer (MS) and the like can be preferably used. Of these, a thermal conductivity detector or a flame ionization detector is more preferable.

(Carrier gas)
As the carrier gas, a carrier gas usually used in gas chromatography can be used, and for example, helium gas, argon gas, nitrogen gas and the like can be preferably used.

(Method for evaluating adsorption behavior of organic compound vapor in the present invention)
FIG. 1 shows a method for evaluating the adsorption behavior of an organic compound vapor according to the present invention. First, the column 3 filled with the adsorbent 4 to be evaluated is installed in the column tank 2. The organic compound is introduced into the column 3 together with the carrier gas from the column 3 entrance. The organic compound vapor moves in the column 3 following the carrier gas while repeating the gas-solid distribution equilibrium with the adsorbent 4 in the column 3, reaches the outlet of the column 3, and is detected by the detector 5. . The signal from the detector 5 is processed by the calculator of the recorder to obtain a chromatogram of the organic compound vapor.

From the obtained chromatogram, the time required from the time when the organic compound vapor was injected until it was detected by the detector to the time required for the carrier gas to reach the outlet from the inlet of the column through the void in the column was calculated. The subtracted time, that is, the holding time tr is calculated. If the retention time of the reference substance is trs, the retention index I is calculated by the following equation.

The amount of adsorption during breakthrough, which is important as an evaluation index for adsorbents in industrial processes, can be calculated as follows. That is, the breakthrough time is calculated from the time from when the organic compound vapor adjusted to a predetermined concentration is passed through the adsorbent at a predetermined flow rate until the concentration at the outlet reaches the breakthrough concentration after the organic compound vapor starts to flow. And the amount of adsorption at breakthrough is calculated from the product of the raw material concentration, breakthrough time and flow rate. As the breakthrough concentration, the emission regulation concentration is generally selected, but is not limited to this, and is freely selected within the range of several ppb to several thousand ppm, and more preferably within the range of several tens of ppb to several hundred ppm. Can do.

The adsorption ratio R is defined by the following equation as an index indicating the adsorption power of the organic compound vapor to the adsorbent in the flow system. Here, Qb and Qe represent the adsorption amount during breakthrough and the equilibrium adsorption amount measured at the same temperature, pressure, and organic compound vapor concentration, respectively.

The adsorption ratio R indicates that the larger the value, the larger the amount of adsorption at breakthrough, that is, the more preferable adsorption in an industrial process. By preliminarily measuring the breakthrough adsorption amount Qbs and the equilibrium adsorption amount Qes of the reference material to calculate the adsorption ratio Rs of the reference material, and measuring the retention index of the evaluation target organic compound vapor by the method according to the present invention, The adsorption ratio of the organic compound can be predicted. That is, when the retention index I is 0 or more, it can be predicted that “R is greater than equal Rs”, and when the retention index I is a negative value, it is possible to be predicted that “R is less than Rs”. With such an evaluation method, it is possible to predict whether the adsorption ratio will be larger or smaller than that of the reference material without measuring the adsorption breakthrough curve. However, since the retention index is calculated from a measurement value including an error, the present prediction method does not prevent a certain amount of prediction error from being included.

The chromatogram required to calculate the retention index I can be measured with a few tens of minutes, usually several minutes to a long time. Furthermore, by mixing different organic compound species and injecting them, multiple chromatograms can be obtained at the same time. Therefore, it is much quicker and the evaluation method is simpler than the measurement of the adsorption breakthrough curve which takes a long time.

(Experimental example)
The characteristics of the present invention will be described below with specific experimental examples, but the experimental examples do not limit the scope of the present invention.

(Experimental example 1)
The adsorption behavior of methyl ethyl ketone on activated carbon was evaluated using pentane as a reference substance. The method is described below. Activated carbon obtained by carbonizing sewage sludge at 500 ° C. and activating at 850 ° C. is heat treated at 250 ° C. for 6 hours to remove adsorbed moisture, etc., allowed to cool, and then room temperature (25 ° C.) It was 0.43 and 0.74 mmol / g when the equilibrium adsorption amount when it was made to contact the pentane / nitrogen or methyl ethyl ketone / nitrogen mixed gas prepared to about 30,000 ppm below was measured. Next, in order to measure the chromatogram, 0.9 g of the activated carbon was packed in a stainless steel column having an outer diameter of 1/8 inch and a length of 25 cm, and placed in a column tank, and then helium was passed through the column at 250 ° C. Heat treatment was performed for 6 hours. Next, while maintaining the inside of the column tank at 200 ° C. and introducing helium as a carrier gas at a flow rate of 20 ml / min, 0.6 μL each of pentane or methyl ethyl ketone is injected into the vaporization chamber with a microsyringe. The chromatogram was obtained by introducing into the column and detecting pentane or methyl ethyl ketone with a thermal conductivity detector installed behind the column outlet. The retention times calculated from the chromatogram were 2.6 and 23.2 minutes for pentane and methyl ethyl ketone, respectively. Therefore, the retention index of methyl ethyl ketone was calculated to be 0.95. On the other hand, the adsorption amount during breakthrough of the activated carbon was measured as follows using a flow system adsorption evaluation apparatus. 16.8 g of the activated carbon is packed in an adsorption tower having an inner diameter of 16 mm, heated at 250 ° C. for 6 hours while flowing nitrogen through the adsorption tower, allowed to cool, and adjusted to a concentration of about 30,000 ppm at room temperature (25 ° C.). Adsorption breakthrough curve by introducing a mixed gas of pentane / nitrogen or methyl ethyl ketone / nitrogen into the adsorption tower at a flow rate of 400 ml / min and measuring the organic compound vapor concentration with a thermal conductivity detector installed behind the outlet of the adsorption tower Got. The breakthrough time determined from the adsorption breakthrough curve was 8.8 and 21.2 minutes for pentane and methyl ethyl ketone, respectively. The breakthrough concentration was 100 ppm. When the amount of adsorption at breakthrough was calculated from the breakthrough time, it was 0.29 and 0.70 mmol / g for pentane and methyl ethyl ketone, respectively. Therefore, the adsorption ratios of pentane and methyl ethyl ketone were 0.68 and 0.94, respectively. This is an example showing that when the retention index is 0 or more, the adsorption ratio is larger than that of the reference material, that is, the adsorption force is increased.

(Experimental example 2)
When the same activated carbon was used as the adsorbent in the same manner as in Experimental Example 1 and the retention index of 2-propanol when pentane was used as the reference substance, it was -1.0. Further, since the equilibrium adsorption amount of 2-propanol was 0.51 mmol / g and the adsorption amount at breakthrough was 0.26 mmol / g, the adsorption ratio was 0.51, which was lower than the adsorption ratio of pentane. This is an example showing that when the retention index is a negative value, the adsorption ratio is smaller than that of the reference material, that is, the adsorption force is small.

(Experimental example 3)
The retention index of methyl ethyl ketone when using pentane as a reference substance was calculated as 0.07 using commercially available activated carbon (CG48AR manufactured by Nimura Chemical) as the adsorbent in the same manner as in Experimental Example 1. The equilibrium adsorption amounts of pentane and methyl ethyl ketone on the activated carbon were 3.6 and 4.7 mmol / g. Moreover, as a result of measuring the adsorption breakthrough curve using the flow system adsorption | suction evaluation apparatus, the adsorption amount at the time of breakthrough of pentane and methyl ethyl ketone was 2.8 and 4.2 mmol / g. Therefore, the adsorption ratios of pentane and methyl ethyl ketone were calculated as 0.78 and 0.88. This is an example showing that even when the adsorbents are different, the adsorption ratio becomes larger than that of the reference material when the retention index is 0 or more.

Schematic diagram of organic compound vapor adsorption behavior evaluation method according to the present invention

Explanation of symbols

1 Vaporizing chamber 2 Column tank 3 Column 4 Adsorbent 5 Detector

Claims (5)

Chromatogram obtained by filling the column with an adsorbent, injecting the organic compound vapor from the front of the column while circulating the carrier gas through the column, and detecting the organic compound vapor with a detector installed behind the column outlet Method for rapid evaluation of adsorption behavior of organic compound vapors The method according to claim 1, wherein the boiling point of the organic compound is -10 ° C or higher and 400 ° C or lower. 3. The method according to claim 1, wherein the adsorbent is activated carbon, silica gel, alumina or zeolite. The method according to claim 1, 2 or 3, wherein the temperature of the column tank in which the column is installed is -10 ° C or higher and 450 ° C or lower. From the retention index obtained by calculating the common logarithm by dividing the retention time of the organic compound vapor obtained from the chromatogram by the retention time of the reference substance, the adsorption amount at breakthrough when using the organic compound vapor is balanced. The method according to claim 1, 2, 3, or 4, wherein an adsorption ratio calculated by dividing by an adsorption amount is predicted.

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