JPH0610673B2 - Method and apparatus for analyzing hydrocarbon mixtures - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for analyzing a hydrocarbon mixture and an apparatus therefor. More specifically, it relates to an analytical method and apparatus for separating and quantifying a hydrocarbon mixture such as naphtha and gasoline by type such as saturated hydrocarbon, olefinic hydrocarbon and aromatic hydrocarbon.

(B) Conventional technology Conventionally, saturated aliphatic hydrocarbons, unsaturated aliphatic hydrocarbons containing a hydrocarbon mixture such as naphtha and gasoline,
To separate and quantify aromatic hydrocarbon types, see JI
The fluorescent indicator method described in S (JIS K-2536) is used. In this method, a sample containing a mixture of the above types is adsorbed on a specified adsorption tube filled with fine silica gel and a small amount of silica gel with a fluorescent dye, and then developed with isopropyl alcohol, based on the difference in adsorption affinity. The boundaries of each type that are separated into layers are quantitatively determined by using an ultraviolet lamp because the fluorescent dyes also selectively exist at the boundaries. Separately from this, a method for analyzing hydrocarbons using gas chromatography (GC) has been conventionally known for separating hydrocarbon mixtures, but in ordinary GC, only the boiling point is used for analysis. As such, it is difficult to analyze by type of hydrocarbon.

(C) Problems to be solved by the invention However, in the above fluorescent indicator method, the band of the fluorescent dye-attached silica gel accumulating on the boundary surface is not sharp,
For this reason, the measured value is likely to include an individual error by the measurer and has poor reliability or reproducibility. Further, this method has a problem that the analysis time also becomes long.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method and apparatus for analyzing a hydrocarbon mixture by type, which does not include the individual error of the measurer and can be measured in a short time.

(D) Means for Solving the Problems Thus, according to the present invention, a hydrocarbon mixture-containing sample is subjected to gas chromatography to separate it into a non-aromatic hydrocarbon group and an aromatic hydrocarbon group, and these groups are separated. Is detected by a first thermal conductivity detector, and then these groups are sequentially contacted with sulfuric acid to remove the unsaturated hydrocarbon group and the aromatic hydrocarbon group in the non-aromatic hydrocarbon group, Furthermore, the remaining saturated non-aromatic hydrocarbon group is detected by the second thermal conductivity detector, and the saturated non-aromatic hydrocarbon in the sample is detected based on the detection peaks obtained from the first and second detectors. A method for analyzing a hydrocarbon mixture is provided, which comprises quantifying components, unsaturated non-aromatic hydrocarbon components and aromatic hydrocarbon components.

This invention provides a sample non-destructive, saturated non-aromatic hydrocarbon, unsaturated non-aromatic hydrocarbon, and aromatic hydrocarbon type downstream of a separation column in a carrier gas flow path of an ordinary gas chromatograph. Two thermal conductivity detectors (hereinafter referred to as detectors), which have almost the same sensitivity to hydrogen, are connected in series in a pipeline, and the non-aromatic hydrocarbon group and aromatic hydrocarbons separated upstream of these detectors are connected. After detecting the hydrogen group with the detector on the upstream side, the unsaturated non-aromatic hydrocarbon group and the aromatic hydrocarbon group are removed by contact with sulfuric acid and the remaining saturated non-aromatic hydrocarbon group is further downstream. Of the saturated non-aromatic hydrocarbon, unsaturated non-aromatic hydrocarbon and aromatic hydrocarbon based on the detection peaks obtained by the respective detectors. .

The method of the present invention is preferable for each type of the above-mentioned mixture sample of interest up to about 15 carbon atoms.

Sulfuric acid heated to a predetermined temperature is used to remove the types of unsaturated non-aromatic hydrocarbons and aromatic hydrocarbons. A suitable heating temperature is 80 to 120 ° C. 120
If the temperature is higher than ℃, it is not preferable in view of corrosion of the equipment due to the vapor of sulfuric acid, and if it is lower than 80 ℃, the removal is incomplete or insufficient. The heated sulfuric acid is used for the purpose of coming into contact with the gas phase of the removed component transferred by the carrier gas to sulphate this and convert it into a non-volatile substance. Therefore, the sulfuric acid is used in an anhydrous state and used in the carrier gas flow path so that the above contact can be sufficiently performed. Therefore, as one preferable embodiment, a column in which a carrier or the like is impregnated or coated with sulfuric acid or the like is packed and provided in the channel. The carrier is used to increase the contact specific surface of sulfuric acid with respect to the gas phase of the removed component, and a diatomaceous earth carrier, for example, cimarite, which is used for a column packing of a general gas chromatograph is suitable. As a method of coating the above-mentioned sulfuric acid on the carrier in an anhydrous state, water is added to a predetermined amount of carrier and a predetermined amount of sulfuric acid corresponding thereto, mixed and stirred, heated to remove water, and then packed in a column. 120 ° C while flowing carrier gas
Examples include aging at a temperature of about a predetermined time. The ratio of the carrier to sulfuric acid is not particularly limited, but it is suitable to use about 40% by weight of sulfuric acid with respect to the carrier.

The method of the present invention is particularly suitable for analysis of hydrocarbon mixtures such as gasoline, naphtha, etc. Therefore, the unsaturated non-aromatic hydrocarbon means mainly olefinic hydrocarbon.
Therefore, when carrying out the method of the present invention, the separation column set for gas chromatography is selected from a column having a strong polarity such as TCEP, which is capable of separating at least the above-mentioned non-aromatic hydrocarbons and aromatic hydrocarbons. Used. In this case, a trace amount of alcohol, aldehyde, etc. usually contained in the hydrocarbon mixture sample as described above is substantially separated from the components to be measured by this separation column.

In the method of the invention, the two detectors used have their sensitivity ratio determined. In this determination method, for example, a sample containing only a saturated aliphatic hydrocarbon as a hydrocarbon component is introduced into a channel constituted by using these two detectors in series, and the peak areas detected are compared with each other. It is done by things. That is, the sensitivity ratio (R) is given by As / αs from the peak area (As) of the upstream detector and the peak area (αs) of the downstream detector.

From the above, in this method, quantification by type is performed as follows. Ie saturated non-aromatic hydrocarbons
(s), unsaturated non-aromatic hydrocarbons (o), aromatic hydrocarbons (a)
A hydrocarbon mixture sample containing each of the three types is
First, it is separated into (s + o) and (a) by the separation column, and As + o and Aa are obtained from the detector on the upstream side for the detection peak area (A). After that, this sample was contacted with heated sulfuric acid to remove (o) and (a), and then from the detector on the downstream side.
The peak area, αs, of only (s) is obtained. Here, using the relationship with the above sensitivity ratio Then, by measuring the area of Aa from the detected peak, the relative ratio of the area for each type can be calculated. To obtain these in volume%, a standard sample whose volume% for each type is known is measured under the same conditions, and the correction coefficient from the peak area to the volume% is obtained. It is converted by calculating the area.

As a device capable of performing the above measurement, a carrier gas supply unit, a sample introduction unit, and a separation column are provided in this order, and a first thermal conductivity detector for detecting separated samples sequentially transferred from the separation column, and a heating unit. A sulfuric acid-containing trap for contacting with a sample transferred from the detector to remove a predetermined substance in the sample, and a second thermal conductivity detector for further detecting the transferred salel sample from the trap in the order of conduits. A gas chromatograph configured by connection is used.

(E) Action According to the present invention, the hydrocarbon mixture-containing sample is separated into a non-aromatic hydrocarbon group and an aromatic hydrocarbon group by the separation column of the gas chromatograph, and these are not destroyed and are separated into the above groups. However, the unsaturated non-aromatic hydrocarbon group and the aromatic hydrocarbon group chemically react with the sulfuric acid phase after being detected by the first thermal conductivity detector that detects with almost the same sensitivity and then sequentially contacted with heated sulfuric acid. Only the remaining saturated hydrocarbons that have been removed by the second thermal conductivity detector are detected by the second thermal conductivity detector, and thus the amount is quantified for each type based on the peak area detected by each detector.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

(F) Embodiment FIG. 1 is a structural explanatory view of an embodiment of a gas chromatograph apparatus for carrying out the method of the present invention. In the figure, in the gas chromatograph device (1), a carrier gas supply pipe (a) connected to a carrier gas supply unit (not shown) includes a sample vaporization chamber (2), a separation column (3), and a first heat chamber. The conductivity detector (TCD-1) (4) and the sulfuric acid-containing trap (5) are extended in this order to the second thermal conductivity detector (TCD-2) (6), that is, carrier gas supply. The carrier gas supplied from the section is composed of a single carrier gas supply passage through which the carrier gas is transferred to the second thermal conductivity detector through the first thermal conductivity detector. TCEP is used for the separation column (3).
Is used. A column packed with a carrier coated with sulfuric acid is used as the sulfuric acid-containing trap (5). The separation column (3) and the sulfuric acid-containing trap (5) are provided with heating means (7) and (8) capable of heating each to a predetermined temperature from the outside. The TCD-1 and TCD-2 are each provided with a recording device (not shown).

The sulfuric acid-containing trap (5) was manufactured by the following method. That is, water is added to 10 g of cimarite and 4 g of sulfuric acid, mixed and stirred, heated at 80 to 90 ° C. to remove water, and then packed in a column and placed in the flow path of the gas chromatograph as described above, and then the carrier. Aging was performed for 2 hours at a temperature of about 120 ° C. while flowing a gas.

Using the gas chromatograph (1) having the above-mentioned configuration, the commercially available gasoline was quantified according to the following conditions and procedures.

Conditions for gas chromatography Carrier gas: Helium Carrier gas flow rate: 40 ml / min Separation column: TCEP Column temperature: 80 ° C Sulfuric acid-containing trap temperature: 120 ° C TCD-1, 2: 150 ° C 60 mA First, commercially available gasoline was used for analysis. By the way, TCD-
The chromatograms shown in FIGS. 2 and 3 were obtained from 1 (4) and TCD-2 (6), respectively. In the chromatogram in Figure 2, peaks (As + o) and aromatic hydrocarbons based on saturated hydrocarbons (s) and olefinic hydrocarbons (o)
A peak group (Aa) based on (a) is obtained. On the other hand, in the chromatogram of FIG. 3, a peak (αs) based on saturated hydrocarbon (s) is obtained.

Then, naphtha containing no olefin was measured with the above apparatus under the same conditions as above, and a chromatogram shown in FIG. 4 was obtained from TCD-1 and a chromatogram shown in FIG. 5 was obtained from TCD-2. . 4th in these figures
In the figure, peaks (a) based on saturated hydrocarbon components and peak groups (b) based on other hydrocarbon components were obtained, while in Fig. 5, peaks (c) only of saturated hydrocarbon components were obtained. . Therefore, comparing the area A of the peak (a) in FIG. 4 with the area α of the peak (c) in FIG. 5, the sensitivity ratio R (= A
/ Α) was obtained as 0.993.

Therefore, the relative ratio of each peak area is Required by.

Next, a standard sample (Japan Petroleum Institute) in which the volume percentages of the components (s), (o) and (a) were known as 45.7%, 14.1% and 40.2%, respectively, was measured using the above gas chromatograph apparatus. By comparing the peak area ratio obtained in the same manner as above and the known capacity% to calculate a correction coefficient from the peak area ratio to the capacity%, and by calculating the correction coefficient to the peak area, For the commercial gasoline
The volume% of each of the components (s), (o) and (a) is 50.
It was 8%, 17.0% and 32.2%.

(G) Effect of the Invention According to the present invention, a hydrocarbon mixture can be quantified according to its type by a gas chromatograph having a single channel structure, and the analysis time can be shortened. In addition, since the measurement is performed based on the peak detected by the thermal conductivity detector, it is a reliable and reproducible analysis method that does not include individual errors.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of an embodiment of a gas chromatograph apparatus for carrying out the method of the present invention, FIG. 2 is a chromatogram diagram of commercially available gasoline by TCD-1 of the apparatus of FIG. 1, and FIG. Chromatogram of commercial gasoline by TCD-2 of the apparatus shown in FIG. 4, and FIG. 4 shows TCD-1 of the apparatus shown in FIG.
Fig. 5 is a chromatogram diagram of naphtha containing no olefin according to Fig. 5, and Fig. 5 is a chromatogram diagram of naphtha containing no olefin according to TCD-2 of the apparatus of Fig. 1. (2) …… Sample vaporization chamber, (3) …… Separation column, (4) …… TCD-1, (5) …… Sulfuric acid-containing trap, (6) …… TCD-2, (7) (8) …… Heating means, (a) …… Carrier gas supply line.

Claims (2)

[Claims] 1. A hydrocarbon mixture-containing sample is subjected to gas chromatography to separate it into a non-aromatic hydrocarbon group and an aromatic hydrocarbon group, and these groups are detected by a first thermal conductivity detector, Then, these groups are sequentially contacted with sulfuric acid to remove the unsaturated hydrocarbon group and the aromatic hydrocarbon group in the non-aromatic hydrocarbon group, and then the saturated saturation remaining by the second thermal conductivity detector. Detect non-aromatic hydrocarbon groups,
A saturated non-aromatic hydrocarbon component, an unsaturated non-aromatic hydrocarbon component and an aromatic hydrocarbon component in the sample are quantified based on the detection peaks obtained from the first and second detectors. Method of analyzing hydrocarbon mixtures. 2. A carrier gas supply unit, a sample introduction unit, and a separation column are provided in this order, and a first thermal conductivity detector for detecting separated samples sequentially transferred from the separation column, and heating means are provided. Carbonization in which a sulfuric acid-containing trap that comes in contact with the sample to be transferred to remove a predetermined substance in the sample and a second thermal conductivity detector that detects the sample to be further transferred from the trap are connected in this order through a pipeline. Analyzer for hydrogen mixture.