JPS6253743A - Preparation of co converting catalyst - Google Patents

Abstract

PURPOSE:To enhance conversion efficiency under a wet condition, by forming a hydrophobic polymer by performing polymerization of the monomer of the hydrophobic polymer through the contact with activated carbon and supporting platinum by activated carbon before or after the formation of the hydrophobic polymer. CONSTITUTION:After pretreatment such as washing by hydrochloric acid or drying has been applied to activated carbon with a proper particle size if necessary, a monomer of a hydrophobic polymer is polymerized in a state contacted with activated carbon to perform modifying treatment. Before and after this modifying treatment, activated carbon is immersed in an aqueous or ethanol solution containing H2PtCl6 and subsequently neutralized with an aqueous sodium carbonate solution or dried with hot air. Next, reducing treatment is preformed by an aqueous solution of KBH4 or NaBH4 to support platinum by activated carbon to prepare a CO converting catalyst. The monomer of the aforementioned hydrophobic polymer is trimethoxyvinylsilane or tetrafluoroethylene.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides a CO2 system that can convert CO contained in a gas such as air into CO2 with high efficiency even at room temperature.
The present invention relates to a method for producing an O conversion catalyst.

As a catalyst for converting CO to CO2, catalysts in which platinum is supported on activated carbon are known (for example,
7-36014). This known CO conversion catalyst is
Activated carbon with an appropriate particle size is pretreated with hydrochloric acid washing and drying as necessary, and then treated with chloroplatinic acid (H, Pt (J, .
6H20) After treatment with aqueous solution, drying, then KBH
It is manufactured by reducing with an aqueous solution such as No. 4, washing with water, drying, and then heating at high temperature in air. However, CO conversion catalysts manufactured by such conventional methods,
It is known that if the catalyst is left in a high humidity environment for a long period of time and absorbs moisture, the initial catalyst performance will be significantly reduced and it will take an extremely long time to recover.

The purpose of the present invention is to provide a CO conversion catalyst that exhibits good conversion efficiency even under humid conditions where the gas to be treated containing CO contains a large amount of water in the catalyst. -J thing.

According to the method of this invention, activated carbon of an appropriate particle size is first subjected to pretreatment such as washing with hydrochloric acid and drying as necessary.
A modification treatment is performed in which the hydrophobic 21 monomer is polymerized in contact with the monomer. Hydrophobic polymeric monomers include silanes such as trimethoxyvinylsilane, and fluorinated olefins such as tetrafluoroethylene. The platinum as the catalytic material is supported on the activated carbon in a conventional manner before or after the modification treatment.

For example, in the case of modification treatment using trimethoxyvinylsilane (TMV 8 ), activated carbon has a
It is soaked in a solution of TMVS in water and acetone to a concentration of 10% and then dried. In the case of tetrafluoroethylene (TFE), activated carbon degassed under reduced pressure (e.g. 8 x 10 torr),
An operation is performed to absorb TFE vapor so as to spread it out in equilibrium under pressure. In this way, the monomers attached to or absorbed by the activated carbon, due to their own polymerizability,
Alternatively, it is polymerized by the catalytic action of activated carbon to form a hydrophobic polymer. Moreover, this polymerization reaction is significantly accelerated by irradiation with radiation such as gamma rays. There is no particular limit to the irradiation dose, but if the monomer is TMvS
In the case of RlTFE, good results were obtained with 4.8X10 to 2.3X10R. If the dose is too low, the effect of irradiation will be small, and if the dose is too high, the effect of irradiation will actually decrease.

Platinum loading is carried out before or after the modification process.

Activated carbon is immersed in a water or ethanol solution containing H, PtCJ, and then neutralized with an aqueous sodium carbonate solution, or
Or after drying with heated air, KBH4 or N
This can be carried out by reduction treatment with an aBH4 aqueous solution. More preferably, as a post-reduction treatment and drying treatment, an oxidation treatment with hydrogen peroxide is performed to decompose the remaining reducing agent.

In this oxidation treatment, the catalyst after reduction treatment and drying is placed in hydrogen peroxide water having a concentration of, for example, about 396 ml.

This can be accomplished by shaking at room temperature for an appropriate amount of time.

The amount of platinum supported on activated carbon is preferably 6rng/
It is preferable that it is more than g・activated carbon.

Furthermore, according to the experimental results, the CO conversion efficiency of the catalyst modified according to the present invention tends to be lower in dry conditions than that of the unmodified catalyst. It is preferable to use it in combination with a catalyst that does not contain a catalyst.

Example 1 Commercially available activated carbon was washed continuously with IN HCl at 100° C. for 20 hours. Then, it was washed with distilled water at 100°C for 40 hours and dried at room temperature.

The activated carbon subjected to the above pretreatment was heated to 8 x 10 torr.
After degassing with r, the mixture was equilibrated in TFB vapor at normal pressure, and then irradiated with γ-rays from C8-60 for polymerization.

Various samples with different γ-ray irradiation amounts and TFE absorption amounts,
The water absorption and CO conversion efficiency were measured for comparative samples that were not subjected to modification treatment with TFE, and the results are summarized in Table 1 together with the comparative examples.

To measure the amount of water absorbed, 10007
The experiment was carried out using the so-called climate chamber method, in which water-saturated air at 37° C. was flowed throughout the day and night at a flow rate of /min.

The water absorption amount is expressed as the difference before and after this operation, and the degree of denaturation is shown as the value 38 below.

(1) Water absorption amount (g) (2) Water absorption rate (water absorption amount/dry weight) (3) Modification rate (water absorption rate/modified/water absorption rate/undenatured) and conversion efficiency can be measured using the measuring device shown in the figure. Measured. In this measuring device, air containing 1 g of CO was introduced into the sample gas holder 1 through the pulp v1 and then supplied to the catalyst section 4 via the air washing bottle 2 and the flow meter 3 under the action of the pump P2. This catalyst section 4 was filled with a catalyst sample, and the ratio was calculated from the CO concentrations before and after the catalytic reaction.

Note that platinum was supported by one of the following two methods.

(g)) Modified activated carbon was heated to 90°C with H, PtCA!
It was immersed for 4 hours in an aqueous solution containing H, Pt (
J, is reduced by KBH,.

(G) In order to support Pt on the modified activated carbon, H
, PtCl, and a reduction treatment is performed at 300° C. for 8 hours using H2 as a reducing agent.

Example 2 Activated carbon was immersed in a solution of trimethoxyvinylsilane in a mixture of water and acetone for 24 hours, and then dried to support the silane. The amount of silane supported was 0.1 wt%.

Next, Example 1 was applied to the activated carbon supporting this silane.
A treatment for supporting TFE was carried out under the same conditions as described above. Note that no radiation was applied.

The measurement results of the water absorption and conversion efficiency of the obtained catalyst were
Shown in the table.

Example 3 From Table 1, it was found that the greater the degree of denaturation (the smaller the value, the less water is absorbed), the higher the conversion efficiency in a wet state. I looked into it.

The silane was deposited at various coverages by immersing the activated carbon in solutions of trimethoxyvinylsilane dissolved in a mixture of water and acetone at various concentrations and then drying. Irradiation with gamma rays from Co-60 was performed after this drying.

Table 3 summarizes the results of measuring the water absorption of the various CO conversion catalysts obtained. Furthermore, the hydrophobicity of activated carbon modified with silane is significantly higher than that modified with TFE (the conversion rate value is much smaller than 1.0), and it exhibits extremely high CO conversion efficiency under wet conditions. Since this is obvious, the measurement results of conversion efficiency will be omitted.

Table 3

[Brief explanation of the drawing]

The reason is the flow sheet of the measuring device used to measure the conversion efficiency of the CO conversion catalyst obtained by the method of this invention. Patent Applicant Industrial Development Research Institute, PA1 Representative Patent Attorney 1) Hiroshi Sawa 1 (Other 2)
given name) '

Claims (4)

[Claims] (1) The activated carbon is subjected to a modification treatment to form a hydrophobic polymer by polymerizing the monomer of the hydrophobic polymer in contact with the activated carbon, and at the same time, before or after this modification treatment, platinum is added to the activated carbon. A method for producing a CO conversion catalyst, characterized in that it supports a CO conversion catalyst. (2) The method according to claim 1, wherein the monomer of the hydrophobic polymer is trimethoxyvinylsilane and/or tetrafluoroethylene. (3) The method according to claim 2, wherein the polymerization of the monomer is carried out under irradiation with radiation. (4) A CO conversion catalyst in which platinum is supported on activated carbon that has been subjected to the modification treatment and a CO conversion catalyst in which platinum is supported on activated carbon that has not been subjected to modification treatment are mixed. The method according to any one of paragraphs 1, 2 and 3.