JPS62190465A - Total organic carbon analyzer - Google Patents

Abstract

PURPOSE:To maintain activity and to make exact measurement with good reproducibility by using catalysts contg. the catalyst component existing not only on the surface of a hard porous gel base body but also into the inside thereof for a combustion catalyst for total carbon and reaction catalyst for inorg. carbon. CONSTITUTION:The porous catalyst 201 obtd. by mixing ethyl silicate, pure water, hydrogen chloride and chloro platinic acid at specific ratios, gelling the mixture after hydrolysis and crushing the gel then subjecting the powder to a heat treatment is packed into the combustion pipe 21 for total carbon. The reaction catalyst obtd. by mixing ethyl silicate, catalyst liquid, ethanol and pure water at specific ratios and subjecting the mixture of gelling, crushing and heat treatment is packed onto the reaction pipe 31 for inorg. carbon. A selector valve 7 is then changed over the side (a) and a flow rate control valve 62 is adjusted to admit the prescribed high purity air into high/low temp. furnaces 2/3. The temps. in said furnaces are set and about 0.1N-HCl and pure water are allowed to flow from a feed port 211 to activate the catalyst 201. After the valve 7 is changed over to the side (b), 1ppm sodium hydrogen phthalate soln. and 1ppm sodium carbonate sodium hydrogencarbonate soln. are respectively injected through feed ports 211 and 311, then the measurement is made.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industry, [6] Field of initial use This invention relates to an all-a-machine carbon analyzer. More specifically, the present invention relates to a total organic carbon analyzer with improved combustion catalysts for total carbon and decomposition catalysts for inorganic carbon.

(b) Conventional technology Conventionally, a total organic carbon analyzer has been equipped with a carrier gas supply section for pure oxygen or an inert gas containing oxygen, a sample introduction section, a heating furnace, and a combustion catalyst equipped with a combustion catalyst for total carbon. This is a combustion-infrared total organic carbon analyzer equipped with a reaction tube equipped with a reaction catalyst for inorganic carbon, a heating furnace, and a non-dispersive infrared gas detection section. ), alumina surface coated with platinum black or quartz wool plated with platinum black are used.On the other hand, the above-mentioned inorganic carbon reaction catalyst (IC catalyst) is coated with phosphoric acid on the surface of a quartz chip. Those coated with ion exchange resin, those filled with ion exchange resin, etc. are used.

(c) Problems to be solved by the invention However, using a conventional total organic carbon analyzer! I
II-description line-'] and I-description lj'l M 'J T
(/IL Catalyst・K-1-Q In the combustion section using the IC catalyst, the catalyst components tend to peel off from the substrate, etc., and the activity of the catalyst decreases during measurement. Also, in the combustion section using the latter IC catalyst, When a relatively non-volatile acid such as phosphoric acid is used, the liquid phase of the acid is held on the surface of the substrate in the form of a thin film, so the retention is insufficient and the life of the catalyst is shortened, and the surface of the liquid phase The catalyst activity lacked stability due to contact with each other, which increased the gas flow resistance, and it was difficult to adjust the flow rate of the device, which caused measurement errors to increase.Also, the coating There were problems such as the acid solution scattering together with the carrier gas, corroding the inside of the piping, and shortening the life of the device itself.

Furthermore, when the ion exchange resin or the like is used, halogens and the like are difficult to remove and give a positive error to a non-dispersive infrared analyzer, resulting in analysis errors and poor reliability.

This invention was made in view of the above circumstances, and in particular, by improving the catalyst used in the combustion section, it is an attempt to provide a carbon analyzer with IE 41 and I11 performance. (2) Means for Solving Problems Thus, according to the present invention, the present invention provides a carrier gas supply section for pure oxygen or an inert gas containing oxygen, a sample introduction section, and a heating furnace. A combustion-infrared overnight carbon analyzer equipped with a combustion tube equipped with a combustion catalyst, a reaction tube equipped with a heating furnace and a reaction catalyst for inorganic carbon, and a non-dispersive infrared gas detection section, The combustion catalyst for combustion is a porous catalyst that is based on a gel obtained by hydrolysis of metal alkoxide and contains a catalyst component consisting of a noble metal and/or a noble metal compound on the surface and inside of this gel, while the reaction catalyst for inorganic carbon is characterized in that it is a porous catalyst that uses a gel obtained by hydrolysis of a metal alkoxide as a base, contains a catalyst component consisting of an acid and/or a noble metal compound on the surface and inside of this gel. A full-strike carbon analyzer is provided.

The combustion catalyst for total carbon and the reaction catalyst for inorganic carbon used in this invention both have a porous gel body obtained by treating metal alkoxide as a base, and contain and fix catalyst components in the inside J5 and the surface of the base. It is a catalyst.

The above-mentioned metal alkoxides include metals that have high valence and can form a three-dimensional network structure, such as group 3B or group 4B metals.
Metal alkoxides made of metals of Group typical elements or metals of Group 4A transition elements are suitable, and examples thereof include Nran alkoxide, aluminum alkoxide, titanium alkoxide, and the like.

In addition, a lower alkokino group is suitable for the alcoquine group,
Examples include ethoxy group and propioxy group.

Examples of the metal alkoxides include tetraethquinsilane S i (OCtH5), triethoxyaluminum A I (OCtHS)3, and tetrapropioxytitanium T.
+(OC3to1,)-, etc. may be mentioned, and tetraethquine is particularly preferred.

1:5c used in this invention! Gold, silver, and platinum group elements are suitable as noble metals serving as catalyst components of the combustion catalyst (for TC), and for example, gold, silver, platinum, copper, and mercury 1 are used.

. Phosphoric acid and sulfuric acid, which are acids capable of catalyzing decomposition reactions, are suitable as acids serving as catalyst components of the reaction catalyst for "-2IC" used in this invention.

For the catalyst component of the reaction catalyst, the above acid and the above noble metal compound may be used in combination, and the noble metal compound serving as the halogen removing agent is suitably a normal compound containing the above noble metal as an ion, such as phosphoric acid and the like. Examples include combinations of silver nitrate and the like.

The catalyst used in the analyzer of the present invention can be obtained by mixing the metal alkoxide solution and the raw material of the catalyst component, and then hydrolyzing the alkoxide to gel it. Gelation of an alkoxide can be achieved by dissolving it in a water-containing hydrophilic organic solvent, safely adding an acid as a hydrolysis accelerator, and subjecting it to drying conditions at mild temperatures to promote hydrolysis and solvent volatilization. . As the water-containing hydrophilic organic solvent, it is appropriate to use a volatile organic solvent containing water such as water-containing ethanol and water-containing methanol. Since the catalyst component is acidic, is there no need to add it specially? Mineral acids such as hydrochloric acid, nitric acid, and hydrofluoric acid are usually suitable, and if added so that the pH of the solution is adjusted to about 2 = 5. That's enough.

The mixing ratio of the metal alkoxide solution and the raw material of the catalyst component is 0.05% to 1.0% (weighted ratio) for the catalyst for TC, I.
In the case of a catalyst for C, it is preferable to prepare the catalyst so that it contains 1 to 20% (heavy weight ratio).

The noble metal and/or noble metal compound, which is one of the raw materials for the catalyst component, is preferably used as a solution containing the specified noble metal ions and/or noble metal compound ions in order to homogeneously contain it in the gel described below. As this solution, a corresponding precious metal halide acid solution is suitable, for example, chloroplatinic acid (H2p t c
le・6H,O), chloroauric acid (HtA uCIs・6
Hto), etc.

In addition to the hydrochloric acid solution, 1. Portrait: Includes 3 genera Iono 1
'' solution, silver nitrate solution (8 gNO3) y'f (
j can be used.

Furthermore, it is preferable to use the acid, which is also one of the catalyst components, in the form of a 1 to 20% solution from the viewpoint of hydrolysis and the catalytic effect in the resulting gel.

The porous catalyst used in the analyzer of this invention is obtained by further heat-treating the gel/catalyst component mixture obtained by the above hydrolysis in the presence of oxygen. Since the gel is brittle, it is partially converted into an oxide [S i (OH)4=S io
t) To obtain a hard gel. In addition, when the catalyst component is a noble metal, this treatment is also for preparing a high-purity catalyst by burning impurities in the raw material of the component.

The above heating conditions may be air drying depending on the type of catalyst component and the use of the catalyst, or usually 100 to 90%
It is preferable to carry out the process gradually at a high temperature of about 0° C. in terms of the uniformity of the gel obtained. By controlling the conditions, the desired porous shell can usually be obtained in 0.5 to 12 hours5.
In this case, treatment at 1000° C. or higher for 24 hours or more is not preferred because the porosity will be lost. Follow-)
For example, when using platinum and converting it into platinum black, it must be treated at a high temperature, but in this case the treatment time must be as short as possible, and 800° C. for one hour or less is suitable.

The combustion catalyst for total carbon and the reaction catalyst for inorganic carbon, which are porous catalysts obtained by the above method, have shapes depending on the purpose in the combustion part and the reaction part, for example, spherical, angular,
Used in crushed form, etc.

The combustion section of the analyzer of the present invention is normally one known in the art, which is equipped with a heating furnace equipped with a heating means and a temperature control means, and a combustion tube capable of holding the combustion catalyst in the furnace. .

The above-mentioned combustion tube preferably has an internal volume that can sufficiently accommodate the amount of catalyst to be produced, and has heat resistance that can withstand the combustion temperature (approximately 600°C) of the batter material of the sample. 14, outer diameter 16 and length 250 (unit: mm)
Examples include quartz tubes.

- The reaction section of the analyzer of the present invention is generally known in the art, and includes a heating furnace equipped with a heating means and a temperature control means, and a reaction tube capable of holding the reaction catalyst in the furnace. used.

The reaction tube is preferably made of a material that has a sufficient internal volume to accommodate the intended amount of catalyst and is resistant to oxidation reactions, for example, an inner diameter of 14, an outer diameter of 16, and a length of 160
(Unit +n+n) Pyrex tube, etc. are mentioned.

The analyzer of the present invention can use any total organic carbon analyzer known in the art or each component of the analyzer, except for using the porous catalyst described above.

(E) Function According to the analyzer of the present invention, the preparation of a base gel and the catalyst components impregnated into the gel are uniformly prepared in the solution state for the combustion catalyst for total carbon and the reaction catalyst for inorganic carbon. Fine particles of catalyst components are captured and contained in the network structure of the gel that is formed during the process of gel formation, sequentially filling the growing del network, and further, as the base gel dries, these catalyst particles are Because we use a gel that is densely packed and has catalyst components uniformly present inside the gel and on the gel network on its surface, it is difficult for the catalyst components to separate from the substrate during measurement in combustion catalysts, and the gel is porous. The catalytic components are densely packed inside the reactor and the surface area with catalytic ability is expanded, so the catalytic activity continues, and even though the reaction catalyst contains an acid solution,
Since the catalyst surface is relatively dry and wet, the flow path resistance is kept low and the surface area having catalytic ability is expanded.

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

(f) Example (1) shown in FIG. 1 is an example of the all-night carbon analyzer of the present invention.

In the figure, (2) is a high temperature furnace for combustion, (3) is a low temperature furnace for decomposition reaction, (4) is a photometry section, (5) is a calculation section, and (6) is a carrier gas supply section.

(2) All-carbon combustion tube (TC combustion tube, (21)
) as inner diameter 14, outer diameter 16 and length 250 (unit: m)
m) is equipped with a quartz tube, and (3) is equipped with an inorganic carbon reaction tube (I
A Pyrex tube with an inner diameter of 14.16 mm and a length of +60 mm (unit: mm) was provided as the C reaction tube (31)).

(4) includes a detector (not shown) that detects changes in the concentration of carbon dioxide generated in the sample as changes in the capacitance of the microphone capacitor, a sample cell (41), and a comparison cell (41).
2) and a non-dispersive infrared spectrometer (NDIR, (43)) with a light source (not shown).

(5) includes a calculation section (51), a storage section (52), and a display section (53).

(6) includes an air cylinder (61) and a flow control valve (62).
and a flow meter (63).

The TC combustion tube (21) is filled with 20 g of a total carbon combustion catalyst (201) prepared by the method described later, while the IC reaction tube is filled with an inorganic carbon reaction catalyst (301) prepared by the method described later. ) was filled in 20g.

After piping the flow path of the analyzer as shown in Figure 1, the flow path switching valve (7) is set to the A side, and high purity air is supplied from the cylinder (61) into the flow path at a flow rate of approximately 150 m1/sin. ] using the flow rate control valve (62) and flow meter (63), and set the temperature of the high temperature furnace (2) to approximately 680'C' and the temperature of the low temperature furnace (3) to approximately 150'C'. and conditioning.

Next, from the TC injection port (211), about 0. IN-HCI
Inject 2°Oug of water 4.5 times, and then add the same amount of pure water 4.5 times.
．． The above combustion catalyst (201) was injected 5 times and filled into the pipe.
) was activated and the lateral switching valve (7) was set to the mouth side.

Two types of samples (1) and (II) prepared by the method shown below were placed in the analyzer (1) set as above.
was injected from (211) and (I[) from (311) using a microsyringe (10 μg) and measured three times, and the results shown in FIGS. 2 and 3 were obtained, respectively.

Sample (T) I ppm sodium hydrogen phthalate solution Sample (II) 1 ppm sodium carbonate/sodium hydrogen carbonate solution At this time, the piping resistance was also measured and the combustion tube for TC (21)
Table 1 shows the results of measuring the pressure loss at both ends of the IC reaction tube (31).

Table 2 also shows the reproducibility of the above measured values expressed in terms of coefficient of variation (%).

The above results are shown together with comparative examples.
In this comparison, glass fiber (approximately 10μ
s) The surface of Ig is coated with PL black.
As the catalyst for C, about 20 g of quartz chips (20 to 30 meshes) coated with about 3+e of phosphoric acid (containing about 4% AgNOs) were used.

Preparation example of reaction catalyst for inorganic carbon Ethyl silicate CS i (OC2H5)4), catalyst solution [phosphoric acid solution containing about 4% Ag ions], ethanol and pure water at 30.30:35:5 (1 ratio by weight) The resulting solution was mixed uniformly at a ratio of p) (=about 3), and was hydrolyzed at room temperature for 10 hours.

After that, the obtained gel was crushed into 20 to 30 meshes,
This was heat-treated at about 110° C. for 2 days in the presence of oxygen and dried to partially oxidize the gel to obtain a porous catalyst as a reaction catalyst for inorganic carbon.

Preparation example of combustion catalyst for total carbon Ethyl silicate (S i (OC2H5)-), pure water, hydrogen chloride and chloroplatinic acid (Htptcxs・6H,O)
were uniformly mixed in a ratio of 50:49:0.9:0.1 (weight ratio), pH of the solution at this time = approximately 3), and hydrolyzed at room temperature to form a gel. After crushing the obtained gel into 20 to 30 meshes, heat treatment was performed for 1 hour in an air heating furnace adjusted to about 800°C to produce an all-carbon combustion catalyst in which platinum black was filled and coated on the inside and surface of the gel base. A porous catalyst was obtained.

(See the blanks below) [Table 1] Piping resistance [Table 2] Reproducibility From the results above, the total organic carbon analyzer of the present invention has low piping resistance and good reproducibility.

(G) Effects of the Invention According to the total organic carbon analyzer of the present invention, catalyst components are uniformly distributed not only on the surface but also inside the hard porous gel base in the combustion catalyst for total carbon and the reaction catalyst for inorganic carbon. Since the existing catalyst is used, the catalytic activity is sustained and accurate measurements with good reproducibility are possible, even though peeling of the catalyst component from the substrate and destruction of the gel due to mechanical friction occur.

In addition, as mentioned above, since a porous catalyst is used that does not produce a powder cliff due to gel destruction and does not form a liquid phase on the gel surface, piping resistance in the combustion tube and reaction tube is reduced, resulting in a flow rate of the analyzer. The road resistance can be reduced and analysis operations can be performed easily.

In addition, by using these improved catalysts, COl originally detected from the catalyst can be suppressed to a few ppb,
Precise measurement without the occurrence of so-called system blanks becomes possible.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of an embodiment of the total organic carbon analyzer of the present invention, and FIGS. 2 and 3 are charts showing the reproducibility of measurements by the analyzer of the present invention, respectively. (1)・-・・・・Total organic carbon analyzer, (21)・・・・
... Combustion tube for TO, (31) ... Reaction tube for IC, (41) ... Sample cell, (42) ...
・Comparison cell, (43)---Non-dispersive infrared analyzer (NDIR), (201)---Combustion catalyst for total carbon, (301)---For inorganic carbon reaction catalyst, (
211)...TC injection port, (311)...
...IC injection port. Figure 2 Figure 3

Claims (1)

[Claims] A carrier gas supply section for pure oxygen or an inert gas containing oxygen, a sample introduction section, a combustion tube equipped with a heating furnace and a combustion catalyst for all carbon, and a combustion tube equipped with a heating furnace for inorganic carbon. This is a combustion-infrared total organic carbon analyzer equipped with a reaction tube equipped with a reaction catalyst and a non-dispersive infrared gas detection section, in which the combustion catalyst for total carbon is based on a gel obtained by hydrolysis of metal alkoxide. is a porous catalyst containing a catalyst component made of a noble metal and/or a noble metal compound on the surface and inside of the gel, while the reaction catalyst for inorganic carbon is based on a gel obtained by hydrolysis of a metal alkoxide, and this gel A total organic carbon analyzer characterized in that it is a porous catalyst containing a catalyst component made of an acid and/or a noble metal compound on the surface and inside thereof.