JPS61103543A - Preparation of co conversion catalyst - Google Patents

Abstract

PURPOSE:To elevate the CO conversion efficiency by neutralizing the activated carbon impregnated into an aq. chloroplatinic acid soln. with an aq. sodium carbonate soln. or drying it with heated air, thereafter subjecting it to the reduction treatment and depositing platinum of specified quantity after drying it. CONSTITUTION:After performing the pretreatment such as the hydrochloric acid washing and the drying for activated carbon having the suitable grain size of necessary, it is treated with an aq. H2PtCl6.6H2O soln. Thereafter it is neutralized with an aq. sodium carbonate soln. or dried by heated air and subjected to the reduction treatment with an aq. KBH4 or NaBH4 soln. and dried.Furthermore as the post-treatment after the reduction treatment and the drying, the oxidation treatment by hydrogen peroxide is performed to decompose the remaining reducer. This oxidation treatment can be easily performed by introducing the catalyst after the reduction treatment and the drying into e.g. an aq. hydrogen peroxide of about 3% concn. and vibrating it for a suitable time at room temp.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a CO that can convert CO contained in a gas such as air into COl 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 COl, a catalyst in which platinum is supported on activated carbon is 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 (Hz P t C
It is manufactured by treating with an aqueous solution of KBH, etc., followed by a reduction treatment with an aqueous solution of KBH, etc., washing with water, drying, and heat treatment at high temperature in air. However, CO conversion catalysts manufactured by such conventional methods have the disadvantage that they do not have sufficient CO conversion efficiency, and that the conversion efficiency rapidly decreases as the flow rate of CO-containing gas increases. For example, when the CO concentration at the outlet was 20ppm at 8V5,300hr''1,
．． There is an example of 170 pIm or more for 600 hr-''.

It is an object of the present invention to provide a method for producing a CO conversion catalyst that has a significantly higher CO conversion efficiency than CO conversion catalysts produced by conventional methods.

According to the method of this invention, first, activated carbon of an appropriate particle size is
After performing pretreatment such as hydrochloric acid washing and drying as necessary, H, PtCl, 6H! After treatment with an aqueous solution of 0, neutralized with an aqueous solution of sodium carbonate (Na, CO,) or dried with heated air, this is reduced with an aqueous KBH or NaBH4 solution and then dried. Next, as a post-treatment after reduction treatment and drying, peroxide water 1i-(HtOt)K
The remaining reducing agent is decomposed by oxidation treatment. In this oxidation treatment, the catalyst after reduction treatment and drying is
This can be easily done by placing the sample in a hydrogen peroxide solution with an elutriation level of about 10% and shaking it at room temperature for an appropriate period of time.

Experiments have confirmed that the CO conversion catalyst obtained by drying after oxidation treatment has an extremely high CO conversion rate compared to that obtained by simply heating and drying the oxidation treatment. It was done.

However, such an effect of improving CO conversion efficiency can be obtained only when the amount of Pt supported on the activated carbon is equal to or higher than a predetermined value. That is, in an impregnation operation in which the amount of platinum (pt) supported on activated carbon is less than about 6 mg/g activated carbon, hardly any improvement in CO conversion efficiency is observed. A preferred impregnation operation is such that the supported amount of Pi is about 6 wq/I on activated carbon or more. Furthermore, even if the oxidation treatment is performed by means other than oxidation using hydrogen peroxide, such as high-temperature heat treatment in air, the CO conversion efficiency will not improve.

Example 1 Activated carbon (trade name 1'-BFGj manufactured by Daiichi Carbon Co., Ltd.) 30
0y was immersed in 2 tons of 5-thihydrochloric acid at 90° C. for 1 hour, then taken out, thoroughly washed with water, and then dried at 120° C. for 2 hours for pretreatment.

Next, add this pretreated activated carbon to 1.5 tons of water with H, P
tc l, 6H, 016, 21? (Pt min approx. 6.1
The sample was immersed in a solution containing 0.9 ml of water and kept at 90° C. for 4 hours with occasional shaking. Then K in this mixture, 6
A solution of 0,F Na, C'O, dissolved in 900 cc of water was gradually added dropwise with stirring at room temperature for 30 minutes, then cooled to 0°C, and then IOF's KB H,
A solution prepared by dissolving 1.5 tons of water was gradually added dropwise over 2 hours while stirring. The solid matter was then suction filtered and
After washing with warm water for 2 hours, it was dried at 120° C. for 2 hours.

This catalyst was further oxidized by placing it in 3 tons of trihydrogen peroxide solution, shaking it at room temperature for 1 hour, and then drying it at 20° C. for 2 hours to obtain Sample A. This catalyst is P
The activated carbon was subjected to a containing operation such that it contained t at a ratio of 20.3 x 7 El activated carbon.

For comparison, H, P tC1, 6H, 04, x # (
Sample B (Pt content: 5.2119 J') obtained under the same conditions as the sample except that a Pt content of about 1.50 J') was used (Pt content was 5.2119 J', the impregnation operation was performed to obtain P activated carbon; the same applies hereinafter). Sample C (Pt is I) without oxidation treatment with hydrogen oxide water (2 Misaki/I activated carbon) and Sample D (Pt is 20.3
119/11 activated carbon) was prepared.

A catalytic activity test was conducted using a portion of each sample A, B, C, and DK as a sample, and the CO conversion efficiency was measured. The catalyst activity test was conducted using the test apparatus shown in the figure. In this test device, air containing a known amount of CO was introduced through the pulp (Vl) into the sample gas holder IK.

Then, by the action of the pump (P2), the air is supplied to the catalyst section 4 via the wash via 2 and the flow meter 3. This catalyst section 4
has an inner diameter of 17 mm and a height of 50 cm (volume: 11.3 cId), into which the test sample is filled. A certain amount of the gas that has passed through the catalyst section 4 is stored in the outlet gas separation container 5 through the balfu (■4), where it is stored for a certain period of time while being stirred by the action of the pump (P3), and then pulp (v
5) and sent to a CO analyzer to measure the CO content.

The measurement results of sample A based on the present invention are shown in Table 1 below (conversion rate is 99.9% or more). The sample gas is humid air (not dry air) with 2,360 pIll of CO added, and the sample gas is supplied to the catalyst section 4 at room temperature so that SV≠5.
It was swept away at 000hr'''l.

Table 1 Values when the flow rate is increased to SV=IO,000hr'''1.

Furthermore, according to the results of a similar test conducted on sample C as a comparative example (inlet CO concentration was 1,590 pP),
Under the same conditions, the average CO @ degree for the first 1.5 minutes was 70
It was 0 folding (conversion rate 56.0%) and rose to 800.4 after 6 minutes.

Furthermore, in sample B (inlet CO concentration was 1,590 pI), the average CO concentration during the first 2 minutes was 510 pI) II (conversion rate 68.01%), and after 3.5 minutes it was 412 solutions.

Furthermore, in the sample (inlet CO concentration is z, 250 ppm),
In the case of ``svs, oOOhr'', it was kept below 2 Lord for 10 minutes, but when SV is 10,000 hr-IK, it is 2
110P111 after 2 minutes, increased to 400 after 32 minutes.

Note that after that, when the SV was reduced to 5.000 hr-', it became 2P or less.

The reason why the CO conversion rate of sample B slightly recovered over time compared to sample C is presumed to be due to the effect of the oxidation treatment with hydrogen peroxide solution, but this is due to the small amount of Pt supported. (Pt is 5.2 k/l activated carbon, sample A
(Pi is 20.31Hi/l activated carbon)
It does not have a conversion rate.

Comparing sample A of the present invention and sample sample of comparative example (no H!O! oxidation treatment), the pt is 20.3 in both cases.
mF/, 9 activated carbon) and 8V5,000hr-', the values were all below 2, but when the SV was 10.000 h
When set to r''-', the sample becomes 11 after 12 to 22 minutes.
0pp* ~400? is increasing.

On the other hand, sample A of the present invention, which was subjected to H, O, and oxidation treatment, had a flk of 84pp* after 2 minutes and 80pp* after 10 minutes, which tended to be a little high temporarily at the beginning, but soon 22 minutes after the activity was recovered, the level was already below 29 Pl, and this level has been maintained. That is, it shows excellent activity even at high SV.

Example 2 Activated carbon 30.9 pretreated under the same conditions as Example 1 was added to 100 cc of water with H, PtC1,.6H,01,0,9(
Pt (approximately 0.38N) was immersed in a solution, kept at 90°C for 30 minutes with occasional shaking, and then heated to 120°C.
It was dried at ℃ for 30 minutes. (Drying treatment with heated air of neutralized water with Na, CO, etc.) Next, it was immersed in a solution of 0.51 Na B H dissolved in 200 cc of water and dried at room temperature for 30 minutes. The mixture was vacuum-packed, filtered with suction, washed with water, and then dried at 120° C. for 30 minutes.

Further, this catalyst was oxidized by placing it in 500 cc of trihydric hydrogen peroxide solution, shaking it at room temperature for 1 hour, and then drying it at 20°C for 2 hours to give sample E (Pt was 12
．． 61M! /11 activated carbon) was obtained.

For comparison, 3
Sample F (Pt: 12.6 .mu./11 activated carbon) was obtained by carrying out the same procedure except that it was oxidized by heating with high-temperature air at 00.degree. C. for 3 hours. According to the results of the same catalytic activity test as in Example 1 for Sample E (SV5.300 br-'
, inlet CO concentration 2,350 pp), and the average CO concentration for 2 minutes from the start was 14I 1 ml (conversion rate 99.4 pp), and its change over time was as shown in Table 2.

Table 2 In addition, in a test under the same conditions for comparative sample F.

The average CO concentration during the initial 2 minutes was 482P (conversion rate 79.5
h), CO@ degree is 35P after 1 minute and 176 after 12 minutes.
It was 0 pP.

Example 3 Activated carbon 300I was treated in the same manner as sample A. However, chloroplatinic acid (H, PtC1゜・6 H, O) used in the platinum supporting treatment performed subsequent to the pretreatment.
The amount of is 5.51i (Pt2゜07I), H,0,
In the oxidation treatment, 3 parts of horse O and 3 parts of water were used. This was designated as Sample G, and that without H102 treatment was designated as Sample H. Both have a pt of 6.9 W/? It is activated carbon.

In a catalyst activity test similar to Example 1 (svs, oo.

hr-”, the inlet CO concentration is 2,510 pp1.
1), in the case of sample G, the CO concentration at the outlet was 184 pIm after 6 minutes, 24 pIm after 15 minutes, and 43111N after 30 minutes.

In comparison, sample H had 67 fermentations after 5 minutes and 1 fermentation after 10 minutes.
As for lQppa, sample G according to the invention showed much higher efficiency.

Finally, when we reexamined the effect of the Pt content, we found that sample A (P
t is 20.3 kg/I activated carbon), sample E (12,689/I activated carbon)
I activated carbon, sample G (6,9 cape/11 activated carbon) sample B (
The amount of Pt decreases in the order of 5.2 W/J activated carbon), and accordingly, the initial CO output concentration increases to 2 or less, 4 Ao, 18 ppl, and 510 ppl, respectively, but 6.9 Misaki/II Activated carbon has a practical value of 18, whereas activated carbon has a practical value of 5.
When it becomes 2”P/l activated carbon, the outlet CO concentration is 51opp
It increases rapidly. Therefore, the amount of Pt supported in the present invention is 6
It is necessary to operate so that the activated carbon becomes more than my/I activated carbon.

[Brief explanation of drawings]

The figure is a system diagram of a catalyst activity testing apparatus used in an example of the present invention. Patent applicant: Industrial Development Research Institute (2 others)

Claims (1)

[Claims] After impregnating the activated carbon with an aqueous solution of chloroplatinic acid, neutralizing it with an aqueous solution of sodium carbonate or drying it with heated air, reducing it and then drying it, the activated carbon has a concentration of at least 6 mg/g of activated carbon. A method for producing a CO conversion catalyst, which comprises performing an operation to support platinum, and then contacting it with a hydrogen peroxide solution.