JPH01250859A - Method and apparatus for analyzing hydrocarbon mixture - Google Patents

Abstract

PURPOSE:To respectively easily separate and determine the satd. aliphat. hydrocarbon, unsatd. aliphat. hydrocarbon and arom. hydrocarbon contained in a hydrocarbon mixture sample by utilizing gas chromatography and hydrogen flame ionization detection, etc. CONSTITUTION:The hydrocarbon mixture sample introduced into a carrier gas is first separated to the aliphat. hydrocarbon and the arom. hydrocarbon by a sepn. column 3. The carrier gas in which the hydrocarbons are incorporated in the separated state is divided in flow at a prescribed flow rate ratio. The aliphat. hydrocarbon and arom. hydrocarbon are detected by the hydrogen flame ionization detector 4 on the branch flow passage (b). The unsatd. aliphat. hydrocarbon and the arom. hydrocarbon are removed by contact with a sulfuric acid-contg. trap 5 on the other branch flow passage (c) and thereafter, the remaining satd. aliphat. hydrocarbon is detected by the hydrogen flame ionization detector 7. The satd. aliphat. hydrocarbon, unsatd. aliphat. hydrocarbon and arom. hydrocarbon in the sample are respectively determined in accordance with the detection peaks obtd. from the respective detectors 4, 7 and the prescribed flow rate ratios.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a method and apparatus for analyzing hydrocarbon mixtures. More specifically, the present invention relates to an analytical method and apparatus for separating and quantifying hydrocarbon mixtures such as naphtha and gasoline into saturated aliphatic hydrocarbons, unsaturated aliphatic hydrocarbons, and aromatic hydrocarbons.

(b) Conventional technology Conventionally, hydrocarbon mixtures such as naphtha and gasoline have been treated with saturated aliphatic hydrocarbons, unsaturated aliphatic hydrocarbons, etc. contained therein.
To separate and quantify aromatic hydrocarbons by type, use JIS
Fluorescent indicator method described in JIS K-253
6) is used. In this method, a sample containing a mixture of the above types is adsorbed into a specified adsorption tube filled with fine silica gel and a small amount of fluorescent dye-coated silica gel, and then developed with isopropyl alcohol, based on the difference in adsorption affinity. Because fluorescent dyes are also selectively separated and exist at the boundaries of each type of layer separation,
The m is determined using an ultraviolet lamp. Separately from this, it has been known to use gas chromatography (GC) to analyze hydrocarbons in the separation of hydrocarbon mixtures, but ordinary GC only analyzes boiling points, Therefore, it is difficult to analyze each type of hydrocarbon.

(c) Problems to be Solved by the Invention However, in the above-mentioned fluorescent indicator method, the band of fluorescent dye-attached silica gel that accumulates on the interface is not sharp;
For this reason, the measured value tends to include individual errors by the measurer and has poor reliability or reproducibility. Another problem with this method is that the analysis time becomes long.

The present invention was made in view of the above situation, and particularly aims to provide a method for classifying hydrocarbon mixtures by type and an apparatus therefor, which does not include the individual error of the measurer and can determine the art in a short time. be.

(d) Means for Solving the Problems Thus, according to the present invention, a sample containing a hydrocarbon mixture is subjected to gas chromatography to obtain a carrier gas stream containing separated aliphatic hydrocarbons and aromatic hydrocarbons, This carrier gas stream is divided into two gas streams at a predetermined flow rate ratio, one gas stream is used to detect aliphatic hydrocarbons and aromatic hydrocarbons using a hydrogen flame ionization detector, and the other gas stream is used to detect aliphatic hydrocarbons and aromatic hydrocarbons using a flame ionization detector. After removing unsaturated aliphatic hydrocarbons and aromatic hydrocarbons through a contact treatment process, saturated aliphatic hydrocarbons are detected by a flame ionization detector, and the detection output of each of these flame ionization detectors and the above flow rate are A fractional Fr method for hydrocarbon mixtures is proposed, which is characterized in that saturated aliphatic hydrocarbons, unsaturated aliphatic hydrocarbons, and aromatic hydrocarbons in the sample are each separated and quantified based on the ratio.

In the method of this invention, a sample containing a hydrocarbon mixture is first subjected to gas chromatography (hereinafter referred to as GC), and the aliphatic hydrocarbons (hereinafter referred to as <= hydrocarbons) and aromatic hydrocarbons (hereinafter referred to as hydrocarbons) contained in the sample are first subjected to gas chromatography (hereinafter referred to as GC). It is separated into (hereinafter referred to as (a) hydrocarbon). Here, the sample containing a hydrocarbon mixture is usually a mixture of saturated aliphatic hydrocarbons (hereinafter referred to as (s) hydrocarbons), unsaturated aliphatic hydrocarbons (hereinafter referred to as (o) hydrocarbons), and (a) hydrocarbons. It is possible to test those containing Examples include gasoline, naphtha, etc. In addition, in the method of this invention, cycloalkanes are included in the above (s) hydrocarbons.

The (7i) hydrocarbons (i.e., including (s) and (o) hydrocarbons) and (a) hydrocarbons separated above are each contained in the carrier gas of the GC and exited as a gas stream. The gas flow is divided into two channels at a predetermined flow rate ratio. Here, the predetermined flow rate ratio means the ratio of split flow into two flow paths. One gas flow separated here is detected by a flame ionization detector (hereinafter referred to as PID) as (π) hydrocarbons ((S) and (0) are not distinguished) and (a) hydrocarbons. be done. One gas stream is subjected to a contact treatment with sulfuric acid, (o) the hydrocarbons and (a) the hydrocarbons react with the sulfuric acid and are collected in a trap, and the remaining (s) hydrocarbons are detected by FID. The Rukoto.

For the contact treatment with sulfuric acid, sulfuric acid heated to a predetermined temperature is used. A suitable heating temperature is 80 to 120°C. A temperature of 1206° C. or higher is undesirable in terms of equipment corrosion due to sulfuric acid vapor, and a temperature of 80° C. or lower is undesirable because removal is incomplete or insufficient. The above-mentioned heated sulfuric acid is used to remove components (i.e. (
It is used for the purpose of contacting the gas phase of (0) and (a) hydrocarbon) to sulfate them and convert them into non-volatile substances.

Even if a small amount of inorganic gas is generated due to contact at this time, F
Since it is not detected by ID, there is no problem in the following quantitative determination.

As mentioned above, are the two divided gas flows predetermined? tF,
lk ratio, this flow rate ratio (or split flow ratio,
k) and the correlation between the peak area (A) of the detected peak and the sample volume, the above (s) and (o).

Each hydrocarbon in (a) will be quantified. For details, refer to the description of Examples described later.

This invention also provides a device capable of carrying out the above analysis,
A first analysis flow path that includes a carrier gas supply section, a sample introduction section, and a separation column in this order and is connected to a first FrD that detects a separated sample sequentially transferred from the separation column; (2) A second analytical flow connected between D and D and extending to the second FID through a sulfuric acid-containing trap that contacts the carrier gas containing the separated sample transferred from the separation column and removes a specified substance in the sample. It is also possible to provide an apparatus for analyzing a hydrocarbon mixture comprising:

The separation column used in the apparatus of this invention is suitably a highly polar column used in ordinary GC, such as TCE
P etc. are selected.

The sulfuric acid-containing trap used in the apparatus of the present invention is used in a form that allows sufficient contact with the carrier gas containing the separated sample. One preferred method is to fill a column with a carrier impregnated or coated with sulfuric acid and interpose it in the carrier gas flow path. The carrier is used to increase the contact pressure surface of sulfuric acid with respect to the gas phase of the removed component, and diatomaceous earth carriers used as column packing materials for ordinary gas chromatographs, such as simalite, are suitable. A method for coating the carrier with the sulfuric acid in an anhydrous state is to add water to a predetermined amount of the carrier and a predetermined amount of sulfuric acid, mix and stir, heat to remove water, and then fill the column into a column. Examples include aging at a temperature of about 120° C. for a predetermined period of time while flowing a carrier gas. 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 based on the carrier. Note that the carrier gas flow path of this device may be provided with a purification trap downstream of the trap to collect water vapor and inorganic gas generated in the trap to prevent corrosion of the FID cell portion.

In the apparatus of the present invention, the carrier gas flow path is configured to branch downstream of the separation column. One of the features of this flow path configuration is that the carrier gas containing separated components can be divided into separate channels and measured in parallel in each divided flow path, thereby shortening the measurement time.

Further, in this apparatus, either the first or the second analytical By connecting a carrier gas discharge pipe having a flow path resistance lower than that of the flow path, the configuration is such that detection can be performed with a small amount of carrier gas containing separated components transferred to each detector of the first FID and second PID. You can also do that. By connecting this carrier gas discharge pipe, the amount of sample passing through the sulfuric acid-containing trap can be reduced and the life of the trap can be extended. Further, it is also possible to prevent saturation of FrD (loss of response linearity) in a high concentration region. For details, refer to the description of Examples described later.

(E) Function According to the present invention, a sample containing a hydrocarbon mixture introduced into a carrier gas is first separated into aliphatic hydrocarbons and aromatic hydrocarbons by a separation column. The carrier gas contained in this separated state is then divided at a predetermined flow rate ratio, and on one branch path, the aliphatic hydrocarbons and aromatic hydrocarbons are detected by a hydrogen flame ionization detector, and the other After the unsaturated aliphatic hydrocarbons and aromatic hydrocarbons are removed by contact with sulfuric acid on one of the branch channels, the remaining saturated aliphatic hydrocarbons are detected by a flame ionization detector. Thereafter, saturated aliphatic hydrocarbons, unsaturated aliphatic hydrocarbons, and aromatic hydrocarbons in the sample are each quantified based on the detection peak obtained from each detector and the predetermined flow rate ratio.

The present invention will be described in detail below with reference to Examples, but the present invention is not limited thereby.

(The following is a blank space.) (F) Example 1 is an explanatory diagram of the configuration of an example of a gas chromatograph apparatus for carrying out the method of the invention shown in FIG. 1 if. In the figure, a gas chromatograph device (1) includes a sample separation tube connected from a carrier gas supply section (not shown) to a branch section (p) through a sample injection/vaporization chamber (2) and a separation column (3) in this order. line (CI), and a resistance line (CI) from the branch part (p) to the resistance line (CI).
R,) to the first flame ionization detector (hereinafter FID-
1) The first branch flow path (b) is connected to (4) through the sulfuric acid-containing trap (5), the purification trap (6), and the resistance pipe (R7) in this order from the branch part (p). 2 A second branch flow path (c) connected to a hydrogen flame ionization detector (hereinafter referred to as FED-2) (7), extending from the branch part (p) to the split vent via a resistance pipe (r). The carrier gas discharge pipe (d) is mainly composed of a carrier gas discharge pipe (d).

TCEP is used for the separation column (3).

Further, the sulfuric acid-containing trap (5) uses a column packed with a carrier coated with sulfuric acid. Note that the separation column (3) and the sulfuric acid-containing trap (5) are usually placed in the same column oven.

Further, each of the FID-1 and F'ID-2 is equipped with a recording device (not shown).

The sulfuric acid-containing trap (5) was produced by the following method. That is, water is added to simalite log and 4 g of sulfuric acid, mixed and stirred, heated at 80 to 90°C to remove water, and then packed into a column and inserted into the flow path of a gas chromatograph as described above to form a carrier. 120°C with gas flowing
The mixture was heated for 2 hours at a moderate temperature.

The purification trap (6) has the main purpose of absorbing acidic gas and moisture generated in the sulfuric acid-containing trap (5), and is provided to prevent corrosion of the FID-2 cell connected to the subsequent stage. It is something that

The resistance conduits (R1) and (R2) are both set to have a larger resistance than the resistance conduit (r), and by adjusting their sizes, the resistance of the sample separation conduit (Q) and the The split ratio between the first branch channel (b) and the split ratio between the sample separation pipe (Q) and the second branch channel (c) can be adjusted.

In addition, other configuration examples of the apparatus for carrying out the method of the present invention are described in the second section.
As shown in the figure. The apparatus shown in this figure replaces the carrier gas discharge pipe (d) in the apparatus shown in Fig. 1 with the sample separation pipe (0).
The difference is that it is provided between the sample injection/vaporization chamber (2) and the separation column (3), and this flow path configuration can also achieve the same purpose as the apparatus shown in FIG.

Next, the gas chromatograph apparatus (1) having the configuration as shown in FIG. Hydrogen and aromatics (hereinafter referred to as (a))
The following describes the procedure for quantitative analysis of each type of hydrocarbon.

- The analysis conditions are set to the following conditions, for example.

Gas chromatography conditions Carrier gas: Helium Carrier gas flow GL: 40m12/min Separation column: TCEP column temperature
:80~120℃ Sulfuric acid containing trap temperature: 120℃
C Split ratio: (b)/(d)=1/10~
1/100: (c)/(d) = 1710~! /100 In carrying out the above quantitative analysis, either before or after this analysis, the split flow ratio between the first branch channel and the second branch channel and FrD-! It is necessary to determine a correction coefficient that shows the correlation between the peak area obtained by and -2 and the capacity.

First, we will explain these decisions.

Determination of the splitting ratio (k) (o) One sample of naphtha containing no hydrocarbons (STD)
), and when measured under the above conditions, for example, FED-
It is assumed that a chromatogram schematically shown in FIG. 3(a) is obtained from FID-1, and a chromatogram schematically shown in FIG. 3(b) is obtained from FID-2. In this case, (a) in the same figure shows (s) a peak based on hydrocarbons (sl) and a group of peaks based on other (2L) hydrocarbons (am).
On the other hand, in the interpolation diagram (b), a peak (S, ) of only (s) hydrocarbons is obtained. Therefore, the peak (
From the comparison between the area of the peak (S,) (A-+ 5TD) and the area of the peak (S,) (A-! 5TD), the first branch channel (b)
The diversion ratio (k) between the
You can decide that ・・・・・・■.

Correction factor from peak area to capacity (F,,F,,F,)
When measuring under the above conditions using two standard samples with known volume percentages of each type of hydrocarbon (s), (o), and (a) and different concentrations, it was found that, for example, FrD-1 to 4. It is assumed that the chromatogram schematically shown in Figure (A) is obtained, and the chromatogram schematically shown in Figure 4 (B) is obtained from FTD-2. In other words, in the same figure (a), aliphatic (hereinafter (7X)
) hydrocarbons, i.e. ((s)+(o)) hydrocarbons, and (
a) A peak pattern separated into hydrocarbons is obtained,
From the figure (b), it can be seen that (s) a peak based only on hydrocarbons can be obtained. Therefore, in (a) of the same figure, (5)
The peak area for hydrocarbons is A1. . , (a) If the peak area for hydrocarbons is represented by A6, and the peak area is represented by α1 in the same figure (b), first A, = A,
,. -A, is obtained, and by using the above-mentioned branch ratio (k), the relationship A,=α,Xk is obtained. Therefore, A1. . , eighty.

By actually measuring α1, A,,A,,A, can be found, and by correlating these with known capacitances, the correction coefficients (F,,F,,F,) can be determined.

Quantitative analysis by type of sample Commercially available gasoline was fractionated using the apparatus shown in Figure 1 under the same conditions as above, and each FID = 1 and FID
(k) and (F,,F,) determined as above for the detected peaks obtained from -2, respectively.

(s) hydrocarbons in gasoline, (0) using Fa)
The capacity of each of the hydrocarbons and (a) hydrocarbons can be determined.

That is, the carrier gas containing the sample separated into (7i) hydrocarbons (i.e. s+0) and (a) hydrocarbons by the separation column (3) is transferred to the first branch flow path according to the split ratio of the branch part (p). (b), the second branch channel (c) and the split vent. The carrier gas transferred to the first branch channel (b) is subjected to FID-1 (4) to obtain a chromatogram consisting of a peak based on (s+o) hydrocarbons and a group of peaks based on (a) hydrocarbons. . Further, the carrier gas transferred to the second branch flow path (c) first contacts heated sulfuric acid in the sulfuric acid-containing trap (5) to remove (0) hydrocarbons and (a) hydrocarbons, and then
FID-2 (7) remains in the carrier gas (
s) A chromatograph consisting of peaks based on hydrocarbons is obtained. Therefore, the peak area obtained from FID-1 (
Processing As, o) and (Aa) and the peak area (α,) obtained from FID-2 using the splitting ratio (k) and correction coefficient (F, , F, , F,). Accordingly, the capacity can be determined for each type of (s) hydrocarbon, (0) hydrocarbon, and (a) hydrocarbon.

(G) Effects of the Invention According to the present invention, saturated aliphatic hydrocarbons, unsaturated aliphatic hydrocarbons, and aromatic hydrocarbons contained in a hydrocarbon mixture sample can be easily separated and quantified.

Furthermore, since measurement is performed using parallel branch channels, analysis time can be shortened. Furthermore, since the measurement is based on the peak detected by the flame ionization detector, it is a reliable and reproducible analysis method that does not include individual errors unlike the fluorescence method.

In addition, according to the configuration of this invention, since a hydrogen flame ionization detector is used, even if the configuration absorbs inorganic gas generated in the flow path, the quantitative value will not be affected (more accurate analysis will be possible). Furthermore, by providing the device of the present invention with a carrier gas discharge pipe, it is possible to reduce the amount of sample introduced into the means for removing a predetermined component and to extend the life of the removing means. It is also possible to set up a system with one GC equipped with two types.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of one embodiment of a gas chromatograph apparatus for implementing the method of this invention, FIG. 2 is an explanatory diagram of the configuration of another example of the apparatus for implementing the method of this invention, and FIG. A schematic diagram of a chromatogram obtained when naphtha, which does not contain unsaturated aliphatic hydrocarbons, is used as a standard sample in the apparatus shown in the figure. Schematic % formula of chromatogram obtained using standard sample % (3)... Separation column, (4)... First hydrogen flame ionization detector, (5)
... Sulfuric acid containing trap, (6) ... Purification trap, (7) ... Second hydrogen flame ionization detector, (CI
)・・・・・・Pipeline for sample separation. (b)...First branch flow path, (c)......
Second branch flow path, (d)...Carrier gas discharge pipe, (R1) (R7) (r)...Resistance pipe. No. 1 [Two irises 2 q Sunny time Closing time Closing procedure Continued N width Correct Arrival 1 (Method) % formula % 3.Relationship between the person making the amendment and the case Patent applicant address 1, Kuwabara-cho, Nishinokyo, Nakagyo-ku, Kyoto City Name
(199) Shimadzu Corporation Representative Nishihejo
Act 4, Agent 530 Address 1-3 Quarter, Nishitenma 5-chome, Kita-ku, Osaka
Insert column ``3. Detailed description of the invention'' in ``One Bill 6, Detailed description of 1 invention of the store subject to amendment''.

Claims (1)

[Claims] 1. A sample containing a hydrocarbon mixture is subjected to gas chromatography to obtain a carrier gas stream in which aliphatic hydrocarbons and aromatic hydrocarbons are separated and contained, and this carrier gas stream is applied at a predetermined flow rate ratio. Divided into two gas streams, one gas stream is used to detect aliphatic and aromatic hydrocarbons using a flame ionization detector, while the other gas stream is subjected to a contact treatment step with sulfuric acid to detect unsaturated fats. After removing group hydrocarbons and aromatic hydrocarbons, a flame ionization detector detects saturated aliphatic hydrocarbons, and based on the detection output of each of these flame ionization detectors and the above flow rate ratio, A method for analyzing hydrocarbon mixtures, characterized by separating and quantifying saturated aliphatic hydrocarbons, unsaturated aliphatic hydrocarbons, and aromatic hydrocarbons. 2. A first analysis channel that is equipped with a carrier gas supply section, a sample introduction section, and a separation column in this order and is connected to a first flame ionization detector that detects the separated sample sequentially transferred from the separation column; A sulfuric acid-containing trap is connected between the separation column of the column and the first flame ionization detector, and contacts the carrier gas containing the separated sample transferred from the separation column to remove a predetermined substance in the sample. 2. A hydrocarbon mixture analysis device comprising a second analysis channel extending to a hydrogen flame ionization detector.