JPS58207947A - Catalyst for oxidizing carbon monoxide - Google Patents

Abstract

PURPOSE:To enhance activation, by forming the catalyst from at least one catalytic assistant selected from palladium, copper, silver and rare earth metal salts, and an activating assistant such as ammonium persulfate. CONSTITUTION:A catalyst composition is blended with a basic composition of (Pd<2+>+2.0-3.0 X+0.01-0.5 Y) [wherein X is pref. approx. 2 in case of gamma-Al2O3 (having a micropore volume of 0.1-0.5cc/g and a specific surface area of 20- 400m<2>/g, and Y is pref. ammonium persulfate in a range pref. of 0.01-0.5molar or ratio for Pd<2+>=1] based on the amount of Pd<2+>, and treated by a method for accelerating uniform blending or maturing it for 7-10 days. This liquid catalytic composition is used to impregnate into a carrier such as porous ceramics, an amorphous compound, active carbon, alumina or silica.

Description

[Detailed Description of the Invention] The present invention relates to a catalyst that removes carbon monoxide from a gaseous body containing carbon monoxide at room temperature.As is well known, carbon monoxide is used in combustion equipment, heating equipment, vehicles, etc. In addition to being contained in the exhaust gas of

It is also contained in the smoke of cigarettes, etc., and each poses a problem for environmental conservation and human health. However, since carbon oxide has low activity as a catalyst, there are currently very few catalysts that can oxidize it at low temperatures and render it harmless.

The conventionally known fobcalide catalyst consisting of silver-manganese-steel-cobalt oxide is active at room temperature, but is deactivated by a small amount of moisture, and silver oxide and silver permanganate catalysts are active in the presence of moisture. However, although it exhibits activity, it has disadvantages such as a highly stoichiometric reaction, short lifespan, and high cost.

Furthermore, palladium and its weir-based catalysts can convert carbon monoxide into carbon monoxide at room temperature and make it harmless, but there are problems in that a large amount is required and the catalyst is highly carbon monoxide. Conventionally known methods for making palladium into a powerful drug include weir-forming palladium, (PdC12) and clay-forming beak (
Curl, ) e Q plus Pd(0) = Pd(
n) There is a method of imparting activity by reversibly repeating the reaction of C1 (for example, German Patent No. 713,791).
However, this method has a slow reaction rate and has not been put into practical use.

As an improvement method of this method, Pd(n) −Cu(n)
A method of accelerating the 9 reaction rate by adding a small amount of nitrate ions to the catalyst has been proposed (for example, US Pat. No. 3,790,662), but the amount of activity is still insufficient for practical use. This is because the current standards for use are high flow rates and high carbon monoxide content, and Pd
This is because the use conditions must be met with a small amount of catalyst since it is expensive.

The present invention significantly increases the activity of the palladium-based catalyst by adding a unique activation promoter in addition to chlorinated steel to the composition of the palladium-based catalyst, thereby reducing the amount of palladium used conventionally. It made it possible to save 1
The palladium-based catalyst of the present invention (1) has a high rate of oxidation of carbon oxide, and (2) does not deactivate in the presence of moisture in the gas.

(3) It maintains its activity at room temperature, (4) It selectively oxidizes the carbon even in gases containing a large amount of sol, and (5) The catalyst has a similar activity difference. It has excellent performance such as being used in small quantities and being economically inexpensive.

The basic composition of the catalyst of the present invention is OX consisting of pb''+x+y
is Cu”, Ag2+ or Ag+v or La
Indicates salts of rare earth element ions such as 3+, and the main catalyst is Pd.
2+ is restored to Pd' → Pd2+ and the entire composition system is 1) d
It is a promoter component that makes 2+ = Pd0 (cycle), and Y
If it is ammonium persulfate, it is alkaline persulfate.

It is an active co-agent component that promotes the redox function of co-catalyst component X. The preferred ranges of X and Y are shown in molar ratios.SehaPd2
+1 versus TeXlO~3.0. , yo, o 1-0.
It is 5.

The present invention is particularly useful in a correlated reaction system of three basic components. It has been experimentally shown that the action of the active aid component Y on the solvent component X significantly increases the catalyst activity 1.
,,,,I will use what has been proven.

The substance of component Y in the present invention and its effects have been clarified through many experiments.

In descending order of effectiveness, the effects are in the order of a/heptinium persulfate, warm, and alkali persulfates, and show a large difference from the above-mentioned known additives, as will be described later.

Various persulfates decompose at room temperature or in hot water to generate oxygen and change to sulfates or sulfuric acid. 1. To describe the properties of each type of persulfates related to the present invention: (1) Sodium persulfate is highly deliquescent and decomposes at room temperature. (2) Potassium persulfate has a crystal decomposition temperature of about io'c, but its solubility in water is low, about 7% at room temperature.

It is about 10% in hot water. (3) Ammonium persulfate has a crystal decomposition temperature of about 120°C, but its solubility in water is as high as 58% at room temperature. Moreover, when it meets water, it gradually decomposes even at temperatures below 100°C.
Let's break it down in detail.

The role of these persulfates in the present invention is to supply active modification to the catalytic reaction system in the presence of water as an activation aid, and ammonium salts are particularly effective; According to the study, the effectiveness of alkali salts is 60% that of ammonium salts. In addition to the decomposition temperature and water solubility of the salts, which are factors for the effectiveness, ammonium salts have NH4 components. , an ammonium complex salt is formed by the presence of qt moisture in the gas with respect to the wing or rare ±1 element (for example, La3+) of the auxiliary +'A medium component, and -shi! This is thought to be due to the fact that it improves the solubility of carbon monoxide and promotes the degree of association between carbon monoxide and active oxygen in the IPA medium reaction system.

Next, as X, in addition to Cu"+, which has conventionally been used in combination with Pd2+, small amounts of peroxide (Ag") and oxide (Ag"), and rare earth elements such as lanthanum can be used. Oxides such as nitrates are substances with high oxidizing activity and exhibit strong oxidizing effects.The inventors focused on this point, and
Direct oxidation restoration of palladium is possible at room temperature,
Pd2Pd"+Tactile W which is effective for maintaining the cycle,
It was discovered through experiments that the composition was

Mild forms of silver salts are not limited to peroxides. Silver sulfate (Ag2so4. Solubility approximately 057%) has low solubility in water.
Even monovalent salts (Ag'') of roots such as at Q°C) can be used in the catalyst of the present invention, and their performance will be sufficiently exhibited1.The same is true for salts of rare earth elements such as lanthanum. .

From the above, the catalyst composition of the present invention +d palladium and palladium salt, at least one catalyst aid selected from copper salts, silver salts, rare earth salts, and ammonium salt or alkali salt of persulfuric acid. and at least one activation aid. This catalyst composition is used by being supported on various carriers described below.

The catalyst composition of the present invention achieves a high level of activation that could not be achieved with conventional Pd-based catalysts due to the interrelated effects of the basic composition, particularly the effects of the active '11 component and the co-catalyst component described above.

Next, a method for producing the catalyst of the present invention will be explained.

The catalyst of the present invention is prepared by a homogeneous ionic blending method.

The composition of the catalyst is based on the amount of Pd2+, preferably the basic composition (Pd"+2.0~3.oX+o, OJ~
2 within the range of 0.5Y). Among them, the molar ratio of the X component and the X component is determined based on comprehensive consideration of material properties, relationship with the carrier material, usage conditions, etc., and based on the results of many experiments.

First, the ratio between Pd2+ and the X component will be explained with reference to the drawings. The vertical axis of the figure is CO2/CO (contained COi th)
The horizontal axis is the ratio of oxidation to Pd” = 1.
This is the blending ratio of the ingredients. (Y is a compounding ratio of 0.05 ammonium persulfate salt Al2O3 material Vt (pore volume o, i~o, scc/it specific surface area 20~400m1
g>, it is better to be close to 2, and coconut shell activated carbon (pore volume 0.6 to x, occ/, y + specific surface area 900 to 1.20
0m/g), the ion loading after impregnation is slightly affected by the correlation between factors such as the pore diameter, distribution state, and slight reducing property, and factors such as the ion species of the X component and the ionic radius. It has been determined by the amount analysis that, especially in the case of Cu2+, there is a change in yield between the blending ratio of the catalyst composition liquid and the ion support.9 The final ion content in the support is the blending ratio of the above composition formula. It is necessary to adjust the blended amount to match the
This control determines the activity and stability of the catalyst.

In the combination of component X, as mentioned above, the ammonium persulfate salt C(NH4)28208) contributes to excellent catalytic activity, but the alkali salt "k't+su ÷ sham" also shows a certain level.

One thing to keep in mind when formulating these persulfates is that they undergo some decomposition during the impregnation process.

Therefore, the blending ratio is not fixed, and 1 molar ratio is Pd2
The range of 0.01 to 0.5 is preferable for +=1.

Most preferably 0.05-0. This is the range of IO.

The catalyst composition liquid is blended based on the blending ratio of the composition as described above, and adjustment of the concentration of each component is extremely important here. High concentration does not necessarily indicate good performance, and experimental results show that the concentration of each ion in the composition solution is 0.0
Good results are obtained in the range of 01 to O1'; l mol/l.

The composition solution may be blended by a method that promotes uniform blending, such as by artificially stirring the solution or using a high-frequency bath, but it is preferable to allow a maturing time of 7 to 10 days so that the molecular movement of each ion 2. The aged catalyst composition liquid is impregnated into a carrier.

Types of carriers include porous ceramics, ceramic minerals,
They are appropriately selected from amorphous compounds, activated carbon, etc., but the most representative ones are r and z.

a, a-based alumina, activated alumina, amorphous silica alumina, silica gel, diatomaceous earth, zeolite.

It is made of activated carbon, etc.

The impregnation step may be performed by simple immersion, but it is more efficient to carry out the impregnation by discharging the adsorbate on the carrier out of the system under reduced pressure if possible. It is necessary that the specific surface area (value measured by BET method, etc.) of the carrier after impregnation does not decrease significantly compared to before impregnation.

If possible, it is preferable to build the soil before impregnation. The formation of the catalyst on the inner surface of the pores of the carrier is influenced by the ion concentration of the catalyst composition liquid, and this condition can also be determined from the measurement of the specific surface area after the catalyst is formed.

After the impregnation, the catalyst-supported carrier undergoes the first and final drying process, but in order to improve the catalyst activity, it is necessary to maintain the effective contact area with CO gas as large as possible.
For this reason, it is necessary to sufficiently remove the moisture contained in the carrier.

The material of the carrier is ceramics, r-Al□Os”!fc
Although the moisture content differs depending on the type of activated carbon,
In particular, something like activated carbon with a large specific surface area can be used to create ridges.
Immediately after draining, there is a moisture content of 30 to 4 Q wt% or more.

When using a heating method to speed up drying, care must be taken to avoid high temperature heating and sudden temperature changes.
Good results can be obtained by heating at a temperature of preferably 30-45°C and a relative humidity of 70-30%, preferably 60-40%.

It is preferable that the residual moisture in the carrier at the end of drying is 20-10 wt%.

After production, the catalyst is in equilibrium with the moisture in the atmosphere, so storing it in a sealed container or storing it at room temperature at a relative humidity of 60% or less is an effective way to maintain catalyst performance over a long period of time. be.

During the entire process of producing the autocatalyst and during storage, ions such as Za, Fe, FNilCo, Mo,
Needless to say, it is important to control the mixing of ions such as V to prevent them from being mixed in.

The catalyst of the present invention as described above exhibits extremely excellent performance in removing carbon monoxide contained in a gaseous body at room temperature. In other words, even when carbon monoxide coexists with moisture such as cigarette smoke, a large amount of organic gas, and aerosols, and even when the gas has a high flow rate, it is possible to selectively remove carbon monoxide with a small amount of catalyst. It has a high rate of removal and removal performance. It also has the characteristics of long-term durability and economical cost.

The catalyst of the present invention and its effects will be explained below with reference to Examples.

Example 1 (1) 0.05 ml of each ionic liquid as the catalyst of the present invention
mol/it"f:, used, Pd: Cu:
(NH4) 820g = 1:220.5, and after aging the 41 solution at room temperature for 7 days, r-Al 203 Berets (particle size 2~
3 W) under reduced pressure, and then air-dried for 24 hours at room temperature and humidity of 50% to obtain a catalyst.

Catalyst 5I was filled in a glass tube with an inner diameter of 14 mm and a length of about 20 ounces to a length of about 80 mm, and the CO concentration was 1.860 from one end.
Air containing ppm was passed through at 14.5°C for 25 minutes at a flow rate of 250 d/chick. When CO9 degrees were measured every minute and every 5 minutes, the residual CO concentration was on average 674 ppm and the average removal rate was 63.7%. There was no discoloration or deterioration of the carrier or catalyst, and subsequent tests revealed that the activity continued.

[2] As a comparative catalyst, (A) PdC12 alone, (
B) PdC12+ 2CuC12, (Q PdC1z
+ 2CuC12+ KNO3, APdC12+ 2C
uC12+ N)(nNO3, (E) pact2+
2CuC1z-1-AgNO3, each ion i
The mixture was mixed with a solution of l1 degree and 0.05 mol/filter, and the subsequent steps were conducted in the same manner as in (1) to prepare the catalyst impregnated with rAl2O3. (1) and 1 resistance - 009 degrees 1 under conditions
Measurements were made using air containing 860 ppm.

(81, (C), (G) Each catalyst is 1 after the start of fL communication.
For ~5 minutes, CO remains (use 500-800 pI) m
However, in all cases, the color changed within 5 minutes, and black metallic palladium was produced and deactivated. (6) The catalyst developed a black coloration and was deactivated in about 20 minutes.

Table 1 Residual CO # degree (ppm) Time-wise measurement mix gas temperature 15℃, flow 1250g4/min, CO, concentration =
For 1860 ppm ■, the average concentration of residual CO = 57
4ppm.

Average removal rate = 63.7% Example 2 Cu2+ with the composition (1) of Example 1 was converted to La"" (LaCl,
Used) KTt was replaced with Pd-1-2La 40.5 (
NH4)2820B, and in the same manner as in (1), CO was
! The results of measuring the CO urinary removal rate in air containing 1,900 ppm at a time are shown in the following table, and showed approximately the same buildup and durability as the Cu2+ blending composition.

Table 2 (CO1900ppm, /q air) Example 3 PdC12o, l mol/l, CuCl20
．． 2 mol / JLLaC13Q, 2 mol /
1 solution was shaken using distilled water. Coconut shell activated carbon for food additives (Futamura Chemical Co., Ltd. (Kimu CW-35OA)) as a carrier
60 g of each was weighed and charged into two 5 oi Erlenmeyer flasks. Separately, the above solution was added to (A) PdCI□ bath W
60 nl + CuCl 2 hot liquid 63 me,
(H) PdC1□ solution 60 wd + LaC13
Blend in a can with a titration billet so that the solution is 1.8 g, shake thoroughly to make it homogeneous, and prepare a matured product. Add a saturated ammonium persulfate bath solution to this (
5) Add 30 d of each to the solution and (B) solution, shake vigorously for 5 minutes, and then pour into the Erlenmeyer flask containing the coconut shell activated carbon described above. After confirming that the catalyst composition liquid has spread sufficiently and that there is excess liquid at the top, the pressure inside the Erlenmeyer flask is reduced using a running water injector. 2
In ~3 minutes, the gas adsorbed on the activated carbon begins to be released in large quantities, and at the same time, impregnation of ions of the catalyst composition takes place. At this time, when the reduced pressure is increased, decomposition of ammonium persulfate occurs. Control the reaction so that it occurs gradually by loosening the vacuum and preventing bumping.

The impregnation operation is completed in about 15 minutes, and the soaked activated carbon is thoroughly drained by suction filtration or the like. Air dry at a temperature range of 30-40'C for about 3 hours. At this time, collect a small amount of sample and make sure that the amount of elevated water is 20 wt% or less. A catalyst according to the present invention supported on activated carbon was completed in the above factory.

The obtained carrier is coconut husk charcoal (grain 130-50)
The carbon monoxide removal rate of cigarette smoke was measured using the catalyst (Nal, f'h2)t-.

Measurement conditions: 1 time buff 35d/25d, 1 time 1 minute (5
8 seconds pause) The CO loss of the gas for each puff from the 2nd to the 8th puff was measured, excluding the gas for the 1st and 9th puffs.

Measuring instrument - Detection tube, gastic 1: J used test cigarette - [Bayler f to J Smoke collection - 109+m cylinder; Catalyst 2001 using a bite catalyst knife This was in a glass tube with a total inner diameter of 8 - Form a column, d, medium length no length 7, purple smoke collection: taking into account the variations in the manual method, the above side? Under these conditions, purple smoke from three cigarettes was added to the gas pack, mixed and homogenized, the C0 concentration was measured, and it was designated as blank gas J. For the blank gas, the suction pitch is slightly increased and the CO is approximately 7%.t2 This is 00m degrees thicker than the actual standard purple smoke (CO = 5 to 6%).

Catalyst test The purple smoke captured in the gas pack was measured under the same conditions as the suction method described above! ! ! I! Table 3 shows the results of measuring the CO removal rate for all the media columns.

Table 3 Example of COO removal measurement results 4 Saturated solution of a-acid silver (AgzSO4) (approximately
, 02 mol/A') 110 ml/A'
It took one minute of impregnation. Once the activated carbon is fully impregnated with ions, it is filtered using a suction device and is thoroughly breathed! 7t
"Oko; Treasure. PdCl20.1 mol/j
20 d of the im solution and the activated carbon prepared above were impregnated under a pressure of 7ψ. The impregnation treatment was completed in about 10 minutes, and after draining, the sample was dried at room temperature for about 12 hours in a desiccator containing silica gel. Using this catalyst, 0.5 g of a sample was taken, and 200 iJ of the catalyst (number 3) was accurately taken, and the carbon monoxide removal rate of tobacco purple smoke was measured in the same manner as in Example 3. The results are shown in Table 4.

Table 4 Example of CO removal measurement results 5 (1) PdCl20.1mol/! ! , YCI
, -6H200,2mol,/1, Ce (80
4) 2a4H20Q, 2mol/71 each, and solution B were prepared. All of the activated carbon used in Example 3 was used.1.
(5) Pd: Y: (NH4)8208=1
: 2 : 0.5. (B) Pd:Ce: (NH4
)8208 = l: 2: 0.5, (C)
Pd:Y:2820B=1:2:
o, 5 and (D) Pd: Ce: K28z
A composition solution of Os+ = 1: 2: 0.5 was impregnated under reduced pressure, and after draining once, it was air-dried at room temperature to prepare a single solvent. Note that when a Ce 2 solution was used, the Ce 2 solution was first impregnated, and after draining once, the Pd + (PH4) 820B solution was impregnated.

(2) The results of removing CO from tobacco smoke using the same test method as in Example 3 on each of the above-mentioned shafts and banks (CO removal rate) are as follows.

(5) Composition = 24.7%, (To) Composition = 25.1%.

(q composition = 15.9%, bu composition = 16.1%

[Brief explanation of drawings]

The drawing is a graph showing the performance characteristics of the inventive fluid. Agent Kamo Ishizuka Rukakui

Claims (3)

[Claims] (1) Palladium and palladium salts, at least one catalyst aid selected from divalent salts of steel, monovalent or divalent salts of silver, rare earth salts, and ammonium or alkali salts of persulfuric acid. A carbon monoxide oxidation catalyst comprising at least one selected activation aid. (2) The carbon monoxide oxidation catalyst according to claim 1, wherein the molar ratio of palladium IK to catalyst auxiliary agent zo-:to and activation auxiliary agent is 0.01-0.5. (3) A carbon monoxide oxidation catalyst according to claim 1, which is supported on an inorganic porous material.