JPH01219013A - Zeolite containing copper, its production, catalyst for removing o2 from co gas, consisting of zeolite and method for removing o2 in co gas - Google Patents

Abstract

PURPOSE:To obtain the subject catalyst having high activity even after repetitive use and efficiently converting O2 in CO gas to CO2, by mixing water-soluble copper (II) salt with raw material mixture for synthetic zeolite and by calcining the crystal obtd. by crystallization reaction. CONSTITUTION:The crystal is obtd. by adding water-soluble copper (II) salt [e.g., Cu(NO3)2.6H2O] to Na2O-Al2O3-SiO2-H2O synthetic zeolite raw material mixture having, in molar ratio, SiO2/Al2O3=0.5-25, Na2O/SiO2=0.5-1.4 and H2O/Na2O=5-20, so as to control Cu/Al2O3 molar ratio to 0.3-0.7, and by bringing about the crystallization reaction at 50-100 deg.C. Then, the crystal is calcined at 500-650 deg.C to obtain the catalyst contg. copper highly dispersed in the crystal. After activating the catalyst by bringing into contact with CO gas contg. several % O2 at a high temp., O2 in the CO gas is converted to CO2 by bringing the catalyst into contact with the CO gas contg. O2 at <=50 deg.C under an ordinary pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a copper-containing zeolite having a fine structure in which copper is highly dispersed within the crystals, a method for producing the same, and a catalyst for removing 02 from CO gas made of the zeolite. , and a method for removing 02 from CO gas using the catalyst.

Conventional technology When producing high-purity CO gas, it is often required to remove trace amounts of 62 contained in the CO gas. For example, separating and recovering high-purity CO gas from converter gas. In this case, several hundred ppm contained in CO gas
It becomes necessary to remove degree 02.

02 in CO gas can be removed by performing a catalytic reaction between CO and 02 to convert 02 into CO2. It is no exaggeration to say that whether the removal of 02 from CO gas by catalytic reaction is industrially viable depends on the performance of the catalyst.

As a catalyst for this purpose, the inventor has already discovered Cu-Cr2
We are proposing an O3-based catalyst. (Refer to Proceedings of the 50th Annual Meeting of the Chemical Society of Japan, I, 655 (1985)) Problems to be Solved by the Invention As a catalyst for removing 02 from CO gas, it has a high conversion rate (02→C02) even when used repeatedly. Not only can you obtain
It is strongly required for industrialization that it can be used at room temperature and pressure.

However, although the above-mentioned Cu-Cr2O3-based catalyst as a catalyst for removing 02 from CO gas is proposed by the present inventors, the catalytic reaction between CO gas containing 02 and the catalyst is carried out at about 60°C. Since the process must be carried out in a medium temperature range, there is still room for improvement from an industrial perspective.

Therefore, the present inventors proposed a method for impregnating a commercially available zeolite carrier with a copper salt as a catalyst for removing 02 from CO gas;
■Method of supporting copper on commercially available zeolite by ion exchange method, ■Method of mixing zeolite and powdered CuO,
A copper-containing zeolite catalyst was obtained and its catalytic performance was investigated. However, in the case of the catalyst (2), the active sites of the zeolite are covered when copper is supported, resulting in a lower catalytic activity. There were problems such as low catalytic activity due to the low copper content, and catalyst (2) which could not basically be called a copper-containing zeolite and also had low catalytic activity.

In view of these circumstances, the present invention has high activity even after repeated use, and efficiently removes 0 from CO gas even at room temperature and pressure.
This was achieved as a result of intensive research to obtain a copper-containing zeolite catalyst that can convert 2 to CO2.

Means for Solving the Problems Copper-containing zeolites of the present invention, copper is incorporated into the crystals during the crystallization step of zeolite synthesis, and the present invention has a microstructure in which copper is highly dispersed within the crystals. The copper-containing zeolite is characterized in that a water-soluble copper (n) salt is mixed into a raw material mixture of synthetic zeolite to allow a crystallization reaction to proceed, and then the produced crystals are fired.

The catalyst for removing 02 from CO gas of the present invention is made of the above copper-containing zeolite.

The method for removing 02 from CO gas of the present invention is a method for removing 02 from CO gas.
Bringing O gas into contact with a catalyst converts the O2 contained therein into CO2
It is characterized by using the above-mentioned copper-containing zeolite catalyst.

The present invention will be explained in detail below.

As is well known, synthetic zeolite is produced by using alkali, alumina, silica, and water as raw materials, subjecting the raw material mixture to hydrothermal synthesis to crystallize it, and then firing the resulting crystals.

In the present invention, copper is incorporated into the crystals during this crystallization step, thereby obtaining a synthetic zeolite having a microstructure in which copper is highly dispersed within the crystals.

When producing synthetic zeolite, alkali sources include sodium hydroxide, sodium carbonate, and potassium hydroxide, alumina sources include sodium aluminate and potassium aluminate, and silica sources include Aerosil, silica gel, silica sol, and powdered silica glass. etc. are used.

In particular, it is desirable to obtain a Na2O-AM2O3-5 i02-H2O-based synthetic zeolite, and in that case, the preferred composition of the raw material mixture is as follows in molar ratio: 5i02/A2O3 = 0.5 to 25 (especially 0. 5
~5) N a2O/S i02 = 0.5~14H2O/
Na2O=5-50.

Then, it is desirable to allow the crystallization reaction to proceed after adding a water-soluble copper(II) salt having a molar ratio of CuO/A2O3=0.3 to 0.7 to the raw material mixture.

As the water-soluble copper (II) salt, copper (II) nitrate is preferably used, and in addition, copper acetate (■), copper formate (■), copper gluconate (■), copper sulfate (n), copper chloride (II), copper perchlorate (■), copper (II) chlorate, copper dichromate (U
), copper(II) amidosulfonate, and the like are also used.

As the temperature conditions for the crystallization reaction, it is desirable to adopt conditions of 50 to 100°C, especially 70 to 90°C. 50℃
If it is less than 100°C, crystallization will not proceed smoothly, while if it exceeds 100°C, the crystallization reaction will be too rapid and there is a risk that copper will be incompletely dispersed within the crystal.

A suitable crystallization reaction time is 5 to 12 hours; if the reaction time is too short, crystallization will be insufficient, and if the reaction time is not long, it will be disadvantageous in terms of productivity.

After crystal formation, filtration, washing with water, etc. are performed, and after drying, firing is performed.

The crystal firing temperature is 350-700℃, especially 450-85℃
A temperature of 0° C. is appropriate; if the firing temperature is too high or too low, the catalytic activity tends to decrease.

The copper-containing zeolite thus obtained is appropriately molded, granulated, or pulverized to a suitable particle size, and used as a catalyst for removing 02 from CO gas containing trace to small amounts of 02. .

To remove 02 from CO gas, this catalyst is usually packed in a column to form a fixed bed, in which CO containing 02 is removed.
Although it supplies gas, it can also be used as a fluidized bed catalyst.

Examples of CO gas containing trace or small amounts of 02 include gas separated and recovered from converter gas, coke oven gas, blast furnace gas, electric steelmaking furnace gas, etc., and gas obtained from CO reduction reactions of non-ferrous metals and organic synthesis reactions. First, there are various gases.

In the reaction, the catalyst is activated in advance by contacting it with CO gas containing about several percent of 02 at high temperature. Activation is H
It can also be carried out using a reducing gas such as 2.

The catalytic reaction between the CO gas containing 02 and the catalyst can be carried out at any temperature. In this case, the reaction proceeds not only at a high temperature range of 100 to 300°C, but also at a medium temperature range of 50 to 100°C, but also at lower temperatures, especially at room temperature or lower. ,
The greatest advantage of the present invention is that the conversion reaction from 02 to CO2 proceeds smoothly in the high and medium temperature ranges.

Normal pressure is sufficient for the reaction pressure, but the reaction may also be carried out under increased pressure.

Function Next, the function of the present invention will be explained in detail by taking as an example the case where the catalyst of Example 1, which will be described later, is used.

In order to examine the temperature dependence upon activation of the catalyst obtained in Example 1, 2 g of the catalyst obtained above was packed into a quartz reaction tube with an inner diameter of 8.7 am, and the mixture was heated under normal pressure in a reducing atmosphere ( 2
Activation was performed through CO gas containing 000 ppm of 02 (with approximately 5% argon) to examine the CO oxidation performance. The results are shown in FIGS. 1 and 2.

As shown in Figure 1, under reducing conditions, the first
The 02 conversion rate reached about 95% at around 50°C, and from the second time onwards, the 02 conversion rate reached about 95% at around 150°C, and in all cases, no decrease in activity was observed even when the temperature was lowered to room temperature. The reason why the O2 conversion rate was only about 95% was because the reducing atmosphere used happened to contain about 5% argon, so the actual O2 conversion rate was almost 100%.

Next, activation was performed by passing an oxidizing gas (air containing 20000 ppm of CO) as a supply gas, and the co oxidation performance was investigated. The results are shown in FIG.

As shown in Figure 2, under oxidizing conditions, the first
The CO conversion rate reached almost 100% at around 00°C, and after the second time around 250°C, and in both cases, even when the temperature was lowered, the CO conversion rate was 100%.
No decrease in activity was observed up to around 50°C.

From the above, in the catalyst of Example 1, since the copper is highly dispersed inside the crystal, it does not easily undergo oxidation, and therefore maintains the desired 02 conversion ability even after repeated use. I understand.

On the other hand, the catalyst obtained in Comparative Example 1 (copper nitrate on silica gel, (■
) After impregnating with an aqueous solution, calcination and H2 reduction are performed to reduce copper to 8.6
When the temperature dependence of the activation of the compound (wt% supported) was investigated in the same manner as above, the results shown in Fig. 3 were obtained in a reducing atmosphere and in Fig. 4 in an oxidizing atmosphere.

As shown in FIG. 3, reaction characteristics similar to those shown in FIG. 1 were exhibited under reducing conditions. (In addition, the 02 conversion rate is about 95
% because the reducing atmosphere used was one containing about 5% argon, so it was virtually 0.
The conversion rate is approximately 100%. ) However, as shown in Figure 4, under oxidizing conditions, although the reaction characteristics were similar to those shown in Figure 2 during the temperature increase process, the activity began to decrease around 210°C during the temperature decrease process, and the second reaction Almost no changes were observed after that.

From this, it is presumed that in the catalyst of Comparative Example 1, copper is exposed on the surface and has a lower degree of dispersion than the catalyst of Example 1, so that it is easily oxidized.

Example Next, the present invention will be further explained with reference to Examples.

Note that the 02 concentration in the outlet gas was determined by continuously analyzing the generated CO2 using an infrared gas analyzer.

Example 1 [Production of catalyst] In a reactor equipped with a stirrer, 9 g of water glass, 8 g of sodium aluminate, 3 g of copper(II) nitrate, and 1 g of sodium hydroxide were placed in a reactor equipped with a stirrer.
Prepare 2 g and 50 g of water, maintain the temperature at 85°C, and boil for 6
The reaction was carried out for a period of time, and 15 g of crystals were obtained.

The composition of the raw material mixture is S f02 /A12O3 = 1 Na2O/S i02 = 5 H2O/Na2O = 11 in molar ratio, and the amount of copper nitrate (n) added to the raw material mixture is Cuo/AfL2O3 in molar ratio. = 0.5.

After filtering the crystals while still warm, they are washed with cold water,
Subsequently, it was dried in air at 85° C. for 10 hours to obtain 9 g of catalyst raw material.

The obtained catalyst raw material was calcined at 550° C. for 1 hour in an air atmosphere to obtain 6 g of the desired catalyst (copper-containing zeolite).

This catalyst (copper-containing zeolite) was analyzed by XRD and SEM
Observation confirmed that it had an A-type structure.

Furthermore, as a result of analysis using atomic absorption spectrometry, the copper content in the catalyst was found to be 8.
．． It was 8% by weight.

[Removal of 02 from CO gas] 2 g of the catalyst obtained above was filled into a quartz reaction tube with an inner diameter of 8.7 mm, and first, at a temperature of 160°C and under normal pressure, 2O000 pp
Activation was performed by passing CO gas containing 02 of ra.

Subsequently, a gas having a composition of Co 99vo1% 02 11000pp was passed as an inlet gas at room temperature and pressure at a superficial velocity of 2O00/h for 10 hours, and the O2 concentration in the outlet gas was 2OPP11 throughout the entire period. Example 2 After producing a catalyst and activating it in the same manner as in Example 1, a gas having a composition of 500 ppm of Co 99vol 1% 02 was passed through as an inlet gas at room temperature and pressure at a superficial velocity of 3000/h for 30 hours. As a result, the 02 concentration in the outlet gas was 0.8 ppm throughout the entire period.

Example 3 In a reactor equipped with a stirrer, 5 g of water glass, 1 g of sodium aluminate, Ig of copper(II) nitrate, and 1 g of sodium hydroxide were added.
6 g and 140 g of water were charged, and the temperature was maintained at 80° C. and reacted for 30 hours to obtain 12 g of crystals.

The composition of the raw material mixture is as follows in molar ratio: S i02 /AfL2O3 = 5 Na2O/5i02 = lO H2O/Na2O = 30, and the amount of copper(II) nitrate added to the raw material mixture is:
The amount corresponded to a molar ratio of Cuo/AM203 = 0.6.

After filtering the crystals while still warm, they are washed with cold water,
Subsequently, drying was performed in air at 100° C. for 15 hours to obtain 7 g of catalyst raw material.

The obtained catalyst raw material was calcined at 500° C. for 1 hour in an air atmosphere to obtain 5 g of the desired catalyst (copper-containing zeolite). The copper content in the catalyst was 6.5% by weight.

An attempt was made to remove 02 from CO gas in the same manner as in Example 1, except that the catalyst obtained above was used.

The concentration of 02 in the outlet gas remains constant throughout the 5 hour flow period.
5 ppm Comparative Example 1 After impregnating Merck's silica gel in an aqueous solution of steel (II) nitrate, calcination and H2 reduction were carried out to support 8.8% by weight of copper, and after compression molding, It was crushed into 15 pieces.

Example 1 except that the catalyst obtained in this way was used.
An attempt was made to remove 02 from CO gas in the same manner as above.

Initially, the 02 concentration in the outlet gas was 2 Oppm, but after 1 hour, the conversion rate rapidly decreased and the 02 concentration in the outlet gas was 2 Oppm.
After a period of time, it lost its ability to remove O2.

Effects of the Invention The catalyst made of copper-containing zeolite of the present invention can efficiently convert 02 in CO gas into CO2 even at room temperature and pressure, and
Since it has high activity even after repeated use, it becomes possible to remove trace or small amounts of 02 contained in CO gas, which is of great industrial significance.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the CO oxidation performance of the catalyst of Example 1 under reducing conditions, and FIG. 2 is a graph showing the CO oxidation performance of the catalyst of Example 1 under oxidizing conditions.
The solid line is the temperature increasing process, and the dotted line is the temperature decreasing process. FIG. 3 is a graph showing the CO oxidation performance of the catalyst of Comparative Example 1 under reducing conditions, and FIG. 4 is a graph showing the CO oxidation performance of the catalyst of Comparative Example 1 under oxidizing conditions.
The solid line represents the temperature increasing process, and the one-dot line represents the temperature decreasing process. Patent applicant Satoshi Inui Figure 1 Figure 2 Reaction temp, (''C) 2, O9 Co/Air No. 3 Figure 4

Claims (1)

[Claims] 1. A copper-containing zeolite having a microstructure in which copper is incorporated into crystals during the crystallization process of zeolite synthesis and copper is highly dispersed within the crystals. 2. A method for producing a copper-containing zeolite, which comprises mixing a water-soluble copper (II) salt into a raw material mixture of a synthetic zeolite, allowing a crystallization reaction to proceed, and then calcining the produced crystals. 3. The raw material mixture of synthetic zeolite is Na_2O-Al
3. The production method according to claim 2, which is a raw material mixture of _2O_3-SiO_2-H_2O-based synthetic zeolite. 4. The composition of the raw material mixture is as follows in molar ratio: SiO_2/Al_2O_3=0.5-25Na_2O
/SiO_2=0.5-14 H_2O/Na_2O=5-50, and after adding a water-soluble copper(II) salt having a molar ratio of CuO/Al_2O_3=0.3-0.7 to the raw material mixture, crystallization 4. The manufacturing method according to claim 3, characterized in that a chemical reaction is allowed to proceed. 5. The manufacturing method according to claim 2, wherein the crystallization reaction is carried out at a temperature of 50 to 100°C. 6. The manufacturing method according to claim 2, characterized in that the produced crystals are fired at a temperature of 500 to 650°C. 7. The manufacturing method according to claim 2, wherein the water-soluble copper(II) salt is copper(II) nitrate. 8. A catalyst for removing O_2 from CO gas, comprising the copper-containing zeolite according to claim 1. 9. O_2 in CO gas, characterized in that the catalyst according to claim 8 is used when contacting CO gas containing O_2 with a catalyst to convert the O_2 contained therein into CO_2.
How to remove. 10. The removal method according to claim 9, characterized in that the contact between the CO gas containing O_2 and the catalyst is carried out at a low temperature of 50° C. or lower. 11. The removal method according to claim 9, characterized in that the contact between the CO gas containing O_2 and the catalyst is carried out under normal pressure and at normal temperature or lower temperature.