TW202332502A - Catalyst and uses of the same - Google Patents

Abstract

A catalyst and uses of the same are provided. The catalyst comprises an activated carbon carrier; and a first metal oxide, a second metal oxide and a third metal oxide disposed on the activated carbon carrier, wherein the metal of the first metal oxide is at least one of Ru, Rh and Pd; the metal of the second metal oxide is at least one of Mn, Fe, Co and Ni; and the metal of the third metal oxide is at least one of Cu, Zn, Cd, Ag, Ce and Sn.

Description

Catalysts and their applications

The present invention relates to a catalyst and its application. More specifically, it relates to a catalyst and its application in treating ammonia nitrogen wastewater or volatile organic compounds.

In the semiconductor, optoelectronics, chemical industry, and metal product processing industries, pollutants such as ammonia nitrogen wastewater or volatile organic waste gas are often produced, causing harm to the environment and human health. Today, as population density is increasing and environmental quality requirements are gradually increasing, it is urgent to There is a need to develop technologies to deal with this kind of wastewater and exhaust gas pollution.

For ammonia nitrogen wastewater treatment, low-concentration ammonia nitrogen wastewater is traditionally treated biologically. However, because biological treatment requires a large space, it is not conducive to use in small-scale factories. As for the treatment of medium- and high-concentration wastewater, ammonia is usually recovered by gas stripping in an alkaline environment, and then washed with sulfuric acid to produce ammonium sulfate. Here, ammonium sulfate must be purified before it can be recycled. If the ammonium sulfate contains impure impurities, it will cause subsequent waste liquid cleaning problems and cause secondary pollution.

On the other hand, for the treatment of volatile organic waste gas, equipment such as scrubbers and activated carbon towers are traditionally commonly used for treatment. However, these methods will also cause various secondary pollution in the future. Treatment technologies that are less likely to produce secondary pollution include adsorption combined with combustion methods, such as the use of zeolite rotors combined with regenerative incinerators. However, this treatment must be burned at extremely high temperatures of 760°C to 1000°C to eliminate volatiles. Chemical destruction of organic matter requires extremely high energy consumption.

In order to solve the above problems, methods for treating wastewater and waste gas using catalysts have been developed in this field, in which the catalyst is used in the oxidation treatment of volatile organic waste gas or ammonia gas (obtained from ammonia nitrogen wastewater stripping treatment). However, it is currently known that the catalysts used in the aforementioned oxidation treatment need to be operated at temperatures above 200°C, and most of them need to be operated at high temperatures above 250°C. At low temperatures, they have low selectivity for gases (such as ammonia) or The problem of poor conversion efficiency still needs to be solved urgently.

In view of the above technical problems, the present invention aims to provide a catalyst that can catalyze the oxidation reaction of volatile organic waste gas or ammonia at a lower temperature, which can reduce related treatment costs.

Therefore, one object of the present invention is to provide a catalyst, which includes: an activated carbon carrier; and a first metal oxide, a second metal oxide, and a third metal oxide supported on the carrier, wherein , the metal of the first metal oxide is at least one of ruthenium, rhodium, and palladium; the metal of the second metal oxide is at least one of manganese, iron, cobalt, and nickel; and the metal of the third metal oxide It is at least one of copper, zinc, cadmium, silver, cerium and tin.

In some embodiments of the present invention, the metal content of the first metal oxide is 0.01 to 0.2% by weight based on the total weight of the catalyst.

In some embodiments of the present invention, the metal content of the second metal oxide is 0.05 to 0.3% by weight based on the total weight of the catalyst.

In some embodiments of the present invention, the metal content of the third metal oxide is 0.03 to 0.25% by weight based on the total weight of the catalyst.

Another object of the present invention is to provide a method for treating ammonia nitrogen wastewater, which includes: (1) adjusting the pH value of the wastewater to alkaline; (2) stripping the alkaline wastewater to extract ammonia-containing gas ; and (3) oxidizing the gas containing ammonia, wherein the oxidizing treatment is performed in an oxidizing atmosphere in the presence of the above-mentioned catalyst of the present invention.

Another object of the present invention is to provide a method for treating volatile organic compounds, which includes: performing oxidation treatment in an oxidizing atmosphere in the presence of the above-mentioned catalyst of the present invention.

In some embodiments of the method for treating ammonia nitrogen wastewater or volatile organic compounds of the present invention, the oxidizing atmosphere is an atmosphere containing ozone and/or oxygen.

In some embodiments of the method for treating ammonia nitrogen wastewater or volatile organic compounds of the present invention, the oxidation treatment is performed at a relative humidity of 30% to 90%.

In some embodiments of the method for treating ammonia nitrogen wastewater or volatile organic compounds of the present invention, the oxidation treatment is performed at a temperature of no higher than 200°C.

In some embodiments of the method for treating ammonia nitrogen wastewater or volatile organic compounds of the present invention, the oxidizing atmosphere is formed by introducing ozone and/or oxygen into a reaction space, and the space velocity of the introduced ozone and/or oxygen is for 1,000 to 10,000 hours ^-1 .

Another object of the present invention is to provide a use of the above catalyst in gas treatment, wherein the gas system contains at least one of volatile organic compounds and ammonia.

In order to make the above objects, technical features and advantages of the present invention more obvious and easy to understand, some specific implementation aspects are described in detail below.

Some specific implementation aspects according to the present invention will be described in detail below; however, without departing from the spirit of the present invention, the present invention can still be practiced in many different forms, and the scope of protection of the present invention should not be construed as being limited to stated in the instructions.

Unless otherwise indicated in the context, "a", "the" and similar terms used in this specification (especially in the following patent application scope) shall be understood to include both the singular and the plural forms.

Unless otherwise stated in the context, the terms "first", "second" and similar terms used in this specification (especially in the following patent application scope) are only used to distinguish the described elements or components. It has no special meaning and no order of precedence is intended.

The effect of the present invention compared with the prior art is that through the use of the catalyst of the present invention, the oxidation treatment can be performed at a lower temperature, thereby reducing the treatment cost. In addition, the catalyst of the present invention uses activated carbon as a carrier, can be recycled and reused, and is more economical. The following provides a detailed description of the catalyst of the present invention and its application.

1. catalyst

The catalyst system of the present invention contains activated carbon and metal oxide components. Each ingredient is further explained below.

1.1. activated carbon

The catalyst system of the present invention contains activated carbon as a carrier. Activated carbon is a porous carbon-containing material with a high specific surface area and good adsorption properties for substances, especially organic substances.

In the present invention, the type and type of activated carbon are not particularly limited, and may be, for example, granular activated carbon, columnar activated carbon, honeycomb activated carbon carrier, or other activated carbon suitable for exhaust gas treatment. For example, specific examples of activated carbon may include coconut shell activated carbon, coal-based activated carbon, fruit shell activated carbon, activated carbon based on other carbon-containing raw materials or wastes, and combinations of the aforementioned activated carbons, but The present invention is not limited to this.

In the present invention, the specific surface area of the activated carbon can be 800 to 1500 square meters per gram (m ² /g), such as 850 m ² /g, 900 m ² /g, 950 m ² /g, 1000 m ² / g, 1050 m ² /g, 1100 m ² /g, 1150 m ² /g, 1200 m ² /g, 1250 m ² /g, 1300 m ² /g, 1350 m ² /g, 1400 m ² /g, 1450 m ² /g, or within the range composed of any two of the above values.

After the activated carbon is used, it may be regenerated using methods known in the art to remove adsorbed impurities if necessary. Therefore, the catalyst using activated carbon as a carrier of the present invention can be recycled and reused, which is more economical.

1.2. metal oxide

In addition to the aforementioned activated carbon, the catalyst of the present invention also contains metal oxides, wherein the metal oxides are supported on activated carbon as a carrier. The metal oxide can be supported on the activated carbon monomer by any suitable method. For example, the required metal oxide can be evenly distributed with a dispersant and coated on the activated carbon in the form of a thin film, but the invention is not limited thereto.

In terms of the types of metals contained in the catalyst of the present invention, it includes at least three different metal oxides. For convenience, these three different metal oxides are referred to as the first metal oxide and the third metal oxide respectively in this article. Two metal oxides, and third metal oxides, to show the difference.

The metal of the first metal oxide is at least one of ruthenium, rhodium and palladium. In some embodiments of the present invention, based on the total weight of the catalyst, the metal content of the first metal oxide is 0.01 to 0.2% by weight, such as 0.02% by weight, 0.03% by weight, 0.04% by weight, 0.05% by weight. %, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.1 wt%, 0.11 wt%, 0.12 wt%, 0.13 wt%, 0.14 wt%, 0.15 wt%, 0.16 wt%, 0.17 wt%, 0.18% by weight, 0.19% by weight, or within the range composed of any two of the above values.

The metal of the second metal oxide is at least one of manganese, iron, cobalt and nickel. In some embodiments of the present invention, based on the total weight of the catalyst, the metal content of the second metal oxide is 0.05 to 0.3% by weight, such as 0.06% by weight, 0.07% by weight, 0.08% by weight, 0.09% by weight. %, 0.1 wt%, 0.11 wt%, 0.12 wt%, 0.13 wt%, 0.14 wt%, 0.15 wt%, 0.16 wt%, 0.17 wt%, 0.18 wt%, 0.19 wt%, 0.2 wt%, 0.21 wt%, 0.22 wt%, 0.23 wt%, 0.24 wt%, 0.25 wt%, 0.26 wt%, 0.27 wt%, 0.28 wt%, 0.29 wt%, or within the range composed of any two of the above values.

The metal of the third metal oxide is at least one of copper, zinc, cadmium, silver, cerium and tin. In some embodiments of the present invention, based on the total weight of the catalyst, the metal content of the third metal oxide is 0.03 to 0.25% by weight, such as 0.04% by weight, 0.05% by weight, 0.06% by weight, 0.07% by weight. %, 0.08 wt%, 0.09 wt%, 0.1 wt%, 0.11 wt%, 0.12 wt%, 0.13 wt%, 0.14 wt%, 0.15 wt%, 0.16 wt%, 0.17 wt%, 0.18 wt%, 0.19 wt%, 0.2% by weight, 0.21% by weight, 0.22% by weight, 0.23% by weight, 0.24% by weight, or within the range composed of any two of the above values.

By combining the aforementioned at least three metal oxides, the catalyst of the present invention can provide excellent catalytic efficiency for the oxidation reaction of ammonia or volatile organic compounds at a temperature not higher than 200°C, and can be used to treat ammonia nitrogen wastewater or volatile organic compounds. It has excellent gas selectivity and/or conversion efficiency. In addition, as explained above, the catalyst of the present invention does not need to use a large amount of precious metals (ie, ruthenium, rhodium, palladium), and can further control the cost of operation and processing.

2. Methods for treating ammonia nitrogen wastewater

In the method of treating ammonia nitrogen wastewater of the present invention, the catalyst of the present invention is used in the oxidation treatment of ammonia-containing gas extracted from the wastewater through gas stripping. In one embodiment, the method of treating ammonia nitrogen wastewater of the present invention includes: (1) adjusting the pH value of the wastewater to alkaline; (2) stripping the alkaline wastewater to extract gas containing ammonia; and (3) Oxidation treatment is performed on the gas containing ammonia gas, wherein the oxidation treatment is performed in an oxidizing atmosphere and in the presence of the above-mentioned catalyst. This wastewater treatment method is further described below.

2.1. Wastewater alkalization

One embodiment of the method for treating ammonia nitrogen wastewater of the present invention includes a step of alkalizing the wastewater, in which the pH value of the wastewater is adjusted to alkaline to facilitate the conversion of ammonia nitrogen substances contained in the wastewater into ammonia. The operation of adjusting the pH value of wastewater is not particularly limited. Specifically, it can be performed by adding inorganic alkali to the wastewater, such as sodium hydroxide, potassium hydroxide and other substances, but the present invention is not limited thereto. Generally speaking, in this step, the pH value of the wastewater is adjusted to above 10, preferably above 11, for example, the pH value can be adjusted to 11 to 12.5.

2.2. air lift

The so-called gas stripping refers to the process of separating specific substances in a liquid in the form of gas under appropriate conditions. Any conventional gas stripping operation can be used to perform the gas stripping step of the method of the present invention, and gases containing ammonia are extracted by stripping the alkalized wastewater. In the present invention, gas stripping can be performed, for example, by heating the wastewater to 70 to 90° C. and passing high-pressure gas therein, but the invention is not limited thereto.

In the method of treating ammonia nitrogen wastewater of the present invention, two phases, a gas phase and a liquid phase, will be generated after the gas stripping treatment. The gas phase is a gas containing ammonia gas, and the liquid phase is a treatment with a lower ammonia nitrogen concentration. water. The gas phase can be subsequently oxidized, and the liquid phase can be further subjected to other wastewater treatment processes or directly discharged depending on its quality and emission standards. If necessary, a gas/liquid separation step can be performed on the gas phase generated by the gas stripping process to remove the liquid, and the liquid can be recovered and repeated gas stripping; the liquid phase generated by the gas stripping process can also be repeated. Air stripping treatment to improve treatment effect.

2.3. Oxidation treatment

In this step, the gas containing ammonia extracted by gas stripping is subjected to oxidation treatment. This oxidation treatment is performed in an oxidizing atmosphere and in the presence of the catalyst of the present invention.

In some embodiments of the present invention, the oxidizing atmosphere is an atmosphere containing ozone and/or oxygen. For example, the oxidizing atmosphere can be an atmosphere in which ozone, oxygen, or a combination of ozone and oxygen is added to an inert gas or air; the oxidizing atmosphere can also be essentially composed of ozone, oxygen, or a combination of ozone and oxygen; or oxidation The atmosphere can be composed of ozone, oxygen, or a combination of ozone and oxygen.

Oxidation treatment can be carried out under appropriate humidity. In some embodiments of the present invention, the oxidation treatment is performed at a relative humidity of 30% to 90%. For example, the relative humidity can be 32.5%, 35%, 37.5%, 40%, 42.5%, 45%, 47.5 %, 50%, 52.5%, 55%, 57.5%, 60%, 62.5%, 65%, 67.5%, 70%, 72.5%, 75%, 77.5%, 80%, 82.5%, 85%, 87.5%, Or within the range composed of any two of the above values. Preferably, the oxidation treatment of the ammonia nitrogen wastewater treatment method of the present invention is carried out in an atmosphere with a relative humidity of 60% to 90%. If the relative humidity of the oxidation treatment atmosphere exceeds the above range, the desired removal of ammonia may not be provided. Rate.

Oxidation treatment can be carried out at appropriate temperatures. Generally speaking, without destroying the catalyst, the efficiency of oxidation treatment increases as the temperature increases. However, higher operating temperatures also mean higher energy consumption, resulting in increased operating costs. Compared with currently known catalysts, the catalyst of the present invention can perform oxidation treatment at a lower temperature, so the treatment cost can be reduced.

In some embodiments of the present invention, the oxidation treatment can be performed at a temperature not higher than 200°C, preferably not higher than 150°C (eg, 120°C to 150°C). Through the use of the catalyst of the present invention, oxidation treatment can even be performed at a temperature not higher than 100°C (for example: 80°C to 100°C). In another embodiment of the present invention, the oxidation treatment can be performed at room temperature (25°C).

In some embodiments of the present invention, the oxidizing atmosphere is formed by introducing ozone and/or oxygen into a reaction space, and the space velocity of the ozone and/or oxygen introduced into the reaction space is 1,000 to 10,000 hours ^-1 , for example , the space velocity can be 1,100 hours ^- 1, 1,200 hours ^-1 , 1,300 hours-1, 1,400 hours ^{- 1} , 1,500 hours-1, 1,600 hours ^{- 1} , 1,700 hours ^-1 , 1,800 hours ^-1 , 1,900 hours ^-1 , 2,000 hours ^- 1, 2,100 hours ^-1 , 2,200 hours-1, 2,300 hours ^-1 , 2,400 hours ^-1 , 2,500 hours ^-1 , 2,600 hours ^{- 1} , 2,700 hours ^-1 , 2,800 hours ^-1 , 2,900 hours ^-1 , 3,000 hours ^- 1, 3,500 hours ^-1 , 4,000 hours-1, 4,500 hours ^-1 , 5,000 hours- ¹ , 5,500 hours ^-1 , 6,000 hours ^{- 1} , 6,500 hours ^-1 , 7,000 hours ^-1 , 7,500 hours ^-1 , 8,000 hours ^-1 , 8,500 hours ^-1 , 9,000 hours ^-1 , 9,500 hours ^-1 , or within the range composed of any two of the above values. The space velocity may represent the reciprocal of the average residence time of the gas on the catalyst. If the space velocity of the introduced ozone and/or oxygen exceeds the above range, the catalyst may not be able to effectively catalyze the oxidation reaction, resulting in a lower ammonia removal rate. reduce.

2.4. Examples of ammonia nitrogen wastewater treatment

Under the above technical principles and spirit of the present invention, the method of treating ammonia nitrogen wastewater of the present invention can be implemented in various forms using various equipment. Exemplary embodiments of the method for treating ammonia nitrogen wastewater of the present invention will be described below with reference to the accompanying drawings.

Figure 1a is a schematic diagram of one embodiment of the method for treating ammonia nitrogen wastewater according to the present invention. As shown in Figure 1a, wastewater containing ammonia nitrogen substances is first introduced into the first pH adjustment tank through the wastewater inlet, and the pH value of the wastewater is adjusted to alkaline in the pH adjustment tank to provide an alkaline wastewater. Thereafter, the alkaline wastewater is introduced into a stripping tower to extract ammonia-containing gas. Here, compressed air can be introduced into the stripping tower and combined with steam or heat to facilitate stripping. This gas stripping process will produce a gas phase and a liquid phase. Depending on the quality and emission standards of the liquid phase, the liquid phase can be directly discharged, or the liquid phase can be further processed until it meets the emission standards before being discharged. For example, the liquid phase can first enter a heat exchanger to recover heat, and then the cooled liquid phase can be introduced into a second pH adjustment tank if necessary to adjust the pH value to meet the emission standards before being discharged, or in the third The second pH adjustment tank adjusts the pH value to be suitable for subsequent treatment, and then performs subsequent treatment to facilitate discharge. The gas phase may be first introduced into a gas/liquid separator to further remove the liquid, and the liquid is introduced into the first pH adjustment tank for repeated gas stripping to improve the treatment effect. The gas phase obtained by the gas stripping process (or the gas obtained by further gas/liquid separation), that is, the gas containing ammonia, is introduced into the catalyst oxidation tower for oxidation treatment. Among them, the oxidizing atmosphere required for the oxidation treatment can be provided by introducing ozone into the catalyst oxidation tower, and the humidity and temperature required for the oxidation treatment can be provided by adjusting the catalyst oxidation tower with steam and heat. The oxidation reaction is completed in the catalyst oxidation tower, and the ammonia gas is oxidized into water and nitrogen gas and discharged.

Figure 1b is a schematic diagram of another embodiment of the method for treating ammonia nitrogen wastewater according to the present invention. The basic principles and steps of this implementation are the same as the implementation shown in Figure 1a, but oxygen is introduced into the stripping tower instead of compressed air for stripping, and the oxygen enters the catalyst for oxidation along with the gas obtained after stripping. tower to provide an oxidizing atmosphere.

3. How to deal with volatile organic compounds

The present invention also provides a method for treating volatile organic compounds, wherein the oxidation treatment of the volatile organic compounds is carried out in an oxidizing atmosphere and in the presence of the catalyst of the present invention. The above volatile organic matter treatment method will be further described below.

3.1. volatile organic compounds

Volatile organic compounds (VOC) that can be treated by the method of the present invention refer to organic compounds with a boiling point below 250°C under standard atmospheric pressure (101.325 kPa). They often exist in gas form at normal temperature, causing Exhaust gas pollution. The volatile organic compounds include but are not limited to alkanes, alkenes, alcohols, ketones, ethers, aromatic hydrocarbons, esters, aldehydes, or mixtures thereof, such as methylene chloride, ethanol, isopropyl alcohol, ether, acetone , benzene, toluene, phenol, formaldehyde, but not limited to these. One purpose of the present invention is to provide a method for treating these volatile organic compounds to reduce the harm of exhaust gas pollution.

3.2. Oxidation treatment

The method for treating volatile organic compounds of the present invention includes oxidizing the volatile organic compounds. Before the oxidation treatment, the volatile organic compounds can also be treated in other ways. For example, the volatile organic compounds can be first treated in a scrubber and then oxidized, but the invention is not limited thereto.

Here, the oxidizing atmosphere used in the oxidation treatment is the same as that used in the above method of treating ammonia nitrogen wastewater, and can be an atmosphere containing ozone and/or oxygen. For examples of the oxidizing atmosphere and the method of forming the oxidizing atmosphere, please refer to the above description of the method for treating ammonia nitrogen wastewater, and will not be described again here. In the process of forming an oxidizing atmosphere, if the space velocity of ozone and/or oxygen introduced exceeds the range mentioned above, the catalyst may also be unable to effectively catalyze the oxidation reaction, resulting in a reduction in the removal rate of volatile organic compounds.

As explained above for the method of treating ammonia nitrogen wastewater, the oxidation treatment here can also be carried out at a lower temperature, such as not higher than 200°C, preferably not higher than 150°C (for example: 120°C to 150°C) It can be carried out at a temperature not higher than 100℃ (for example: 80℃ to 100℃), or at room temperature (25℃).

As explained above for the method of treating ammonia nitrogen wastewater, the oxidation treatment here can also be carried out under the relative humidity mentioned above. However, for different types of volatile organic compounds, the preferred relative humidity range may be different. Generally speaking, the oxidation treatment of volatile organic compounds can be carried out at a relative humidity of 30% to 90%. Among them, for volatile organic compounds with higher polarity (such as isopropyl alcohol, acetone, etc.), the optimal relative humidity is 60% to 90%; while for volatile organic compounds with lower polarity (such as benzene, toluene, etc.) Generally speaking, the best relative humidity is 30% to 70%. If the relative humidity used in the oxidation treatment exceeds the above range of 30% to 90%, it may not provide the desired removal rate of volatile organic compounds.

3.3. Examples of Volatile Organic Compounds Treatment

Under the above technical principles and spirit of the present invention, the method of treating volatile organic compounds of the present invention can be implemented in various forms using various equipment. Exemplary embodiments of the method for treating volatile organic compounds of the present invention will be described below with reference to the accompanying drawings.

Figure 2 is a schematic diagram of an embodiment of a method for treating volatile organic compounds according to the present invention. The treated substances may be volatile organic compound (VOC) pollution sources, or may be VOC exhaust that still needs further treatment after passing through the scrubber. First, the VOC pollution source or exhaust gas is introduced into the gas/liquid separator for treatment to remove as much liquid as possible and provide volatile organic compounds in the form of gas for oxidation treatment. After that, the volatile organic compounds in the form of gases are introduced into the catalyst oxidation tower for oxidation treatment, wherein the required oxidation atmosphere is provided by introducing ozone into the catalyst oxidation tower, and the ozone is introduced into the catalyst oxidation tower through steam or heating. Provide the required humidity and temperature for the reaction. After the oxidation treatment is finally completed, the treated gas is discharged.

4. Example

The present invention is further illustrated by the following specific embodiments.

4.1. Catalyst preparation

[Preparation example]

Coconut shell activated carbon is used as the carrier. The coconut shell activated carbon is granular activated carbon and the particle size is 20 × 40 mesh. Ruthenium is used as the metal of the first metal oxide, iron is used as the metal of the second metal oxide, and copper is used as the metal of the third metal oxide; and based on the total weight of the catalyst, the amount of ruthenium is 0.02% by weight, and the amount of iron is The dosage is 0.1% by weight, and the dosage of copper is 0.06% by weight. Add ruthenium chloride, ferric chloride and copper chloride to the coconut shell activated carbon according to the aforementioned dosage, slowly drip in sodium bicarbonate and phosphorus-containing dispersant at 80°C for about 3 hours, and control the pH at 8 to 9. Then add an oxidizing agent to oxidize ruthenium chloride, ferric chloride and copper chloride for about 1 hour to form metal oxides of ruthenium oxide, iron oxide and copper oxide, and coat each metal oxide in the form of a thin film evenly distributed On the activated carbon, catalyst A is formed.

[Comparative preparation example]

Coconut shell activated carbon is used as the carrier. The coconut shell activated carbon is granular activated carbon and the particle size is 20 × 40 mesh. Ruthenium is used as the metal of the first metal oxide, and iron is used as the metal of the second metal oxide; based on the total weight of the catalyst, the amount of ruthenium is 0.02% by weight, and the amount of iron is 0.1% by weight. Add ruthenium chloride and ferric chloride to coconut shell activated carbon according to the aforementioned dosage, slowly drip in sodium bicarbonate and phosphorus-containing dispersant at 80°C for about 3 hours, control the pH at 8 to 9, and then add oxidant to Ruthenium chloride and ferric chloride are oxidized for about 1 hour to form metal oxides of ruthenium oxide and iron oxide, and each metal oxide is coated and distributed evenly on the activated carbon in the form of a thin film to form catalyst B.

4.2. Treatment of ammonia nitrogen wastewater

[Example 1]

Use the device system shown in Figure 3 for wastewater treatment. The device system is designed to reduce the ammonia nitrogen concentration of the effluent from the stripping tower to below 120 mg/L to facilitate subsequent use as a biological system. Use other methods to perform nitrification treatment to reduce the overall operating cost of removing ammonia nitrogen substances.

As shown in Figure 3, a biological sludge digestion wastewater is first provided, and ammonia water is added to the biological sludge digestion wastewater to configure it to have an ammonia nitrogen concentration of 1600 mg/liter, so as to conduct continuous testing as raw wastewater. Introduce the raw wastewater into a 50-liter pH adjustment tank, and add sodium hydroxide (NaOH) to the pH adjustment tank to adjust the wastewater to alkaline wastewater with a pH value of 11.

After that, the obtained alkaline wastewater is introduced into a stripping tower with a reaction space of 50 liters and a temperature of 70°C. The inlet flow rate of the alkaline wastewater is 150 liters/hour (L/h), that is, the alkaline wastewater The residence time in the stripper is approximately 20 minutes. High-pressure air is introduced into the stripping tower at a rate of 4.8 cubic meters/hour (m ³ /h) to strip the alkaline wastewater. After the gas stripping treatment, the product flows out through the liquid phase outflow end and the gas phase outflow end. Among them, the liquid phase outflow end flows out of lower concentration ammonia nitrogen treated water, that is, effluent, and the effluent flow rate is 150 liters/hour (L/ h); at the gas phase outflow end, gas containing ammonia flows out.

Afterwards, the ammonia-containing gas flowing out of the gas phase outlet end of the stripping tower was treated by a gas/liquid separator and introduced into an 8-liter catalyst oxidation tower. The interior of the catalyst oxidation tower was filled with 2 liters of the ammonia solution prepared above. Catalyst A prepared in Example. At the same time, the air heated by the electric heater is mixed with the ozone generated by the ozone generator to form a mixed gas, and the mixed gas is introduced into the catalyst oxidation tower to provide an oxidizing atmosphere, where the flow rate of ozone is 1.2 cubic meters/hour. The space velocity of the mixed gas flowing through the catalyst bed is about 3,000 h ^-1 . The gas containing ammonia is oxidized in the catalyst oxidation tower, wherein the temperature of the reaction space of the catalyst oxidation tower is 80°C, the relative humidity is 90%, and the operating pressure is 0.5 kg/cm2 (kg/ cm ² ), and the oxidation treatment was continued for 8 hours.

Analyze the treated gas obtained after the oxidation treatment. The analysis method is as follows: prepare 10 liters of absorption liquid with dilute sulfuric acid, introduce the treatment gas obtained after the oxidation treatment into the absorption liquid, and after 1 hour, introduce the treatment gas into the absorption liquid. The liquid was taken out for analysis and replaced with new absorption liquid, and the process was repeated for a total of 8 hours. Analyze the concentrations of ammonia nitrogen (hereinafter referred to as "absorption liquid ammonia nitrogen"), nitrate nitrogen, and nitrite nitrogen in the absorption liquid introduced into the treatment gas, calculate and record the residual rate of absorbed liquid ammonia nitrogen and the ammonia gas removal rate of the catalyst oxidation tower in Table 1 below. The residual rate of absorbed liquid ammonia nitrogen is divided by the total amount of absorbed liquid ammonia nitrogen per hour divided by the total amount of ammonia nitrogen entering the catalyst oxidation tower per hour. Specifically, it can be calculated by the following formula (1): Formula (1) The ammonia removal rate of the catalyst oxidation tower is 100% minus the residual rate of absorbed liquid ammonia nitrogen. In addition, in this example, no nitrate nitrogen or nitrite nitrogen was detected in the absorption liquid, indicating that the catalyst A has a very high ammonia nitrogen selectivity.

Table 1: Sampling time (hours) 1 2 3 4 5 6 7 8 Ammonia nitrogen in the effluent of the stripping tower (mg/liter) 105 108 103 106 103 98 106 109 Absorption of liquid ammonia nitrogen (mg/liter) 58 102 140 165 160 158 164 156 Absorbed liquid ammonia nitrogen residual rate (%) 0.26% 0.46% 0.62% 0.74% 0.71% 0.70% 0.73% 0.70% Catalyst oxidation tower ammonia removal rate (%) 99.7% 99.5% 99.4% 99.3% 99.3% 99.3% 99.3% 99.3%

[Example 2]

Ammonia nitrogen wastewater was treated in the same manner as in Example 1, but the temperature of the reaction space of the stripping tower was adjusted to 90°C, and the temperature of the reaction space of the catalyst oxidation tower was adjusted to 100°C. The results are shown in Table 2 below. In this example, no nitrate nitrogen or nitrite nitrogen was detected in the absorption liquid, indicating that the catalyst A has a very high ammonia nitrogen selectivity.

Table 2: Sampling time (hours) 1 2 3 4 5 6 7 8 Ammonia nitrogen in the effluent of the stripping tower (mg/liter) 96 100 93 92 102 95 90 94 Absorption of liquid ammonia nitrogen (mg/liter) 140 132 122 126 120 130 118 125 Absorbed liquid ammonia nitrogen residual rate (%) 0.62% 0.59% 0.54% 0.56% 0.53% 0.58% 0.52% 0.55% Catalyst oxidation tower ammonia removal rate (%) 99.4% 99.4% 99.5% 99.4% 99.5% 99.4% 99.5% 99.4%

As shown in Table 1 and Table 2, whether the oxidation reaction is carried out at 80°C (Example 1) or 100°C (Example 2), it has excellent ammonia removal rate, showing that the catalyst A of the present invention has excellent performance in these conditions. It has excellent catalytic effect at low temperature.

The operating conditions and results of Example 1 and Example 2 are further summarized in Table 3. The ammonia nitrogen removal rate of the catalyst oxidation tower in Table 3 represents the average removal rate when equilibrium is reached in the later period, that is, 2 hours before removal. The results are averaged based on the removal rates obtained from the 3rd to 8th hour.

table 3: Example 1 Example 2 operating temperature Gas stripping tower: 70°C Catalyst oxidation tower: 80°C Gas stripping tower: 90°C Catalyst oxidation tower: 100°C Ammonia nitrogen concentration in raw wastewater 1600 mg/L 1600 mg/L Ammonia nitrogen concentration in stripping tower effluent 105 mg/L 95 mg/L Ammonia removal rate of catalyst oxidation tower 99.3% 99.4%

[Comparative example 1]

Ammonia nitrogen wastewater was treated in the same manner as in Example 1, except that Catalyst B prepared in the above comparative preparation example was used instead of Catalyst A for oxidation treatment, and the results are shown in Table 4 below.

Table 4: Sampling time (hours) 1 2 3 4 5 6 7 8 Ammonia nitrogen in the effluent of the stripping tower (mg/liter) 105 103 108 105 110 101 106 104 Absorption of liquid ammonia nitrogen (mg/liter) 68 160 250 294 372 478 575 686 Absorbed liquid ammonia nitrogen residual rate (%) 0.30% 0.71% 1.12% 1.31% 1.66% 2.13% 2.57% 3.06% Catalyst oxidation tower ammonia removal rate (%) 99.7% 99.3% 98.9% 98.7% 98.3% 97.9% 97.4% 96.9%

As shown in Table 4, although Comparative Example 1 has an ammonia removal rate equivalent to that of Example 1 in the first 2 hours, the ammonia removal rate gradually decreases after 2 hours, and has dropped to approximately 96.8 by 8 hours. %. It can be seen that compared with the catalyst A of the present invention, the catalytic effect of the catalyst B used in the comparative example at 80°C is poor.

4.3. Treatment of volatile organic compounds

[Example 3]-

Toluene is used as a volatile organic compound and is processed by the device system shown in Figure 4.

As shown in Figure 4, mixed gas is first provided by a toluene gas cylinder and a nitrogen cylinder, and the concentration of volatile organic compounds (toluene) in the mixed gas is adjusted with a mass flow controller (MFC) so that the mixed gas entering the catalyst bed The volatile organic concentration is approximately 235 ppm. The mixed gas is introduced into the catalyst bed, which is filled with the catalyst A prepared in the above preparation example. The ozone generated by the ozone generator is adjusted by the mass flow controller and analyzed by the ozone analyzer. The gas mixed with ozone is pumped into the catalyst bed through a pump. The spatial velocity of the gas flowing through the catalyst bed is About 3,667 hours ^-1 , so that the ozone concentration in the catalyst bed is maintained in the range of 250 to 280 ppm. In addition, adjust the humidity of the catalyst bed and monitor it with a hygrometer. Oxidation treatment was carried out in this catalyst bed, where the reaction temperature was room temperature (25°C) and the relative humidity was 90%, and the oxidation treatment was continued for 300 minutes. Subsequently, the treated gas obtained after the oxidation treatment was analyzed, including the volatile organic compound removal rate, the produced CO ₂ concentration and the CO concentration, and the results were recorded in Table 5 below.

table 5: Time (minutes) Volatile organic compound removal rate (%) _CO2 concentration (ppm) CO concentration (ppm) 30 96 42 1 60 92 43 1 90 86 44 1 120 83 43 1 150 84 108 2 180 83 129 1 210 83 136 1 240 86 139 2 270 86 140 2 300 87 144 1

As shown in Table 5, at room temperature, even if the treatment time reaches 300 minutes, the volatile organic compound removal rate remains on average above 85%, indicating that the catalyst A of the present invention has excellent catalytic effect at room temperature. In addition, it can be seen from Table 5 that the produced CO ₂ concentration is low in the first 2 hours (120 minutes), but after more than 2 hours, the CO ₂ concentration increases significantly. Without being limited by theory, it is believed that this is due to the first 2 hours. After 2 hours, it is mainly the adsorption reaction of volatile organic compounds catalyzed by the catalyst, and after more than 2 hours, it is mainly the oxidation reaction of volatile organic compounds catalyzed by the catalyst.

[Comparative example 2]

Volatile organic matter treatment was performed in the same manner as in Example 3, except that Catalyst B prepared in the above comparative preparation example was used instead of Catalyst A for oxidation treatment, and the results are shown in Table 6 below.

Table 6: Time (minutes) Volatile organic compound removal rate (%) _CO2 concentration (ppm) CO concentration (ppm) 30 96 42 1 60 90 43 1 90 83 43 1 120 79 43 1 150 72 78 1 180 70 92 1 210 69 105 1 240 70 109 1 270 68 111 1 300 71 115 1

As shown in Table 6, since the first 2 hours are mainly the adsorption reaction of the catalyst adsorbing volatile organic compounds, Comparative Example 2 has a volatile organic compound removal rate equivalent to that of Example 3 in the first 90 minutes, but after 120 minutes The removal rate of volatile organic compounds decreased rapidly, and when the treatment time reached 300 minutes, the removal rate of volatile organic compounds only remained at an average level of about 70%. Obviously, compared with the catalyst A of the present invention, the catalytic effect of the catalyst B used in the comparative example at room temperature is significantly worse.

[Example 4]

Volatile organic matter treatment was performed in the same manner as in Example 3, except that the reaction temperature of the oxidation treatment was adjusted to 80°C and the relative humidity was adjusted to 60%. The oxidation treatment was continued for 300 minutes, and the results are shown in Table 7 below.

Table 7: Time (minutes) Volatile organic compound removal rate (%) _CO2 concentration (ppm) CO concentration (ppm) 30 96.0 42 1 60 95.2 43 1 90 95.8 43 1 120 94.3 43 1 150 95.0 144 1 180 94.4 152 2 210 95.7 157 1 240 94.8 160 1 270 94.6 158 2 300 95.4 156 1

As shown in Table 7, if the oxidation treatment temperature is increased to 80°C, the volatile organic compound removal rate can reach an average level of about 95%. This shows that Catalyst A of the present invention can have excellent catalytic effect at 80°C without raising the temperature to a high temperature such as 200°C, so it has the benefit of reducing treatment costs.

The above embodiments are only for illustrating the principles and effects of the present invention and elucidating the technical features of the present invention, but are not intended to limit the scope of protection of the present invention. Any changes or arrangements that can be easily made by those familiar with the art without violating the technical principles and spirit of the invention fall within the scope of the invention. Therefore, the protection scope of the present invention is as listed in the appended patent application scope.

:without

Figure 1a is a schematic diagram of one embodiment of the method for treating ammonia nitrogen wastewater according to the present invention. Figure 1b is a schematic diagram of another embodiment of the method for treating ammonia nitrogen wastewater according to the present invention. FIG. 2 is a schematic diagram of an embodiment of the method for treating volatile organic compounds according to the present invention. Figure 3 is a schematic diagram of a device system for treating ammonia nitrogen wastewater used in Example 1, Example 2 and Comparative Example 1. Figure 4 is a schematic diagram of a device system for treating volatile organic compounds used in Example 3 and Comparative Example 2.

Claims (11)

A catalyst that includes: activated carbon support; and the first metal oxide, the second metal oxide, and the third metal oxide supported on the support, in, The metal of the first metal oxide is at least one of ruthenium, rhodium, and palladium; The metal of the second metal oxide is at least one of manganese, iron, cobalt, and nickel; and The metal of the third metal oxide is at least one of copper, zinc, cadmium, silver, cerium and tin. The catalyst according to claim 1, wherein the metal content of the first metal oxide is 0.01 to 0.2% by weight based on the total weight of the catalyst. The catalyst of claim 1, wherein the metal content of the second metal oxide is 0.05 to 0.3% by weight based on the total weight of the catalyst. The catalyst as described in claim 1, wherein the metal content of the third metal oxide is 0.03 to 0.25% by weight based on the total weight of the catalyst. A method for treating ammonia nitrogen wastewater, which includes: (1) Adjust the pH value of wastewater to alkaline; (2) Strip the alkaline wastewater to extract gases containing ammonia; and (3) Oxidize the gas containing ammonia, The oxidation treatment is performed in an oxidizing atmosphere in the presence of the catalyst as described in any one of claims 1 to 4. A method for treating volatile organic compounds, which includes: performing oxidation treatment in an oxidizing atmosphere in the presence of a catalyst as described in any one of claims 1 to 4. The method of claim 5 or 6, wherein the oxidizing atmosphere is an atmosphere containing ozone and/or oxygen. The method of claim 5 or 6, wherein the oxidation treatment is carried out at a relative humidity of 30% to 90%. The method of claim 5 or 6, wherein the oxidation treatment is performed at a temperature not higher than 200°C. The method of claim 5 or 6, wherein the oxidizing atmosphere is formed by introducing ozone and/or oxygen into a reaction space, and the space velocity of the introduced ozone and/or oxygen is 1,000 to 10,000 hours ^-1 . An application of using the catalyst of claim 1 for gas treatment, wherein the gas system contains at least one of volatile organic compounds and ammonia.