A catalyst for removing no and its preparation and use

Abstract

The application belongs to the technical field of catalysts, and specifically provides a catalyst for removing NO and preparation and application thereof.The catalyst comprises an active component, an additive and a carrier, wherein the active component is copper oxide, the additive is a multi-metal oxide, and the carrier is active alumina ball; the active component accounts for 3-10% of the weight of the carrier, and the additive accounts for 3-10% of the weight of the carrier.The catalyst has good high-temperature NO removal effect through the synergistic catalysis of the active component and the additive, and the preparation process of the catalyst is simple, convenient to operate, wide in operation temperature range, high in stability and capable of realizing large-scale industrial application.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalyst technology, and specifically provides a catalyst for removing NO and a preparation method and application thereof. BACKGROUND

[0002] Nitrogen oxide (NOx) is one of the main atmospheric pollutants, which is mainly derived from flue gas emitted by coal-fired power plants and motor vehicle exhaust, and has great harm to the ecological environment and human health, which has attracted worldwide attention. There are many technologies for treating NOx, and the most widely used and most mature technology is selective catalytic reduction technology, which selectively reduces NOx in flue gas to N2 and H2O under the action of a catalyst. The catalyst is the core of the technology. Chinese patent application No. CN106423184A discloses a catalyst with vanadium pentoxide and cobalt-based composite metal oxide as active components, which has a NO removal rate of more than 85% at a temperature range of 300-450°C. Although the catalyst has good activity at high temperature, the vanadium pentoxide in the active component has strong toxicity, which can cause harm to people and the environment during use. Therefore, it is of great industrial application value to develop a catalyst with simple preparation method, high NO removal rate, wide operating temperature range, and less harm to people and the environment. SUMMARY

[0003] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a catalyst for removing NO and a preparation method thereof.

[0004] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0005] A catalyst for removing NO, the catalyst comprising an active component, an additive, and a carrier: wherein the active component is copper oxide, the active component accounts for 3-10% of the weight of the carrier, the additive is a multi-metal oxide, the additive accounts for 3-10% of the weight of the carrier, and the carrier is active alumina ball.

[0006] The multi-metal oxide is a combination of any two or more of tungsten oxide, samarium oxide, cerium oxide, iron oxide, and zirconium oxide.

[0007] Preferably, the multi-metal oxide is iron oxide, tungsten oxide, samarium oxide, and zirconium oxide.

[0008] Or the multi-metal oxide is iron oxide, tungsten oxide, and cerium oxide.

[0009] Or the multi-metal oxide is samarium oxide, tungsten oxide, and cerium oxide.

[0010] Or the multi-metal oxide is iron oxide, tungsten oxide, and zirconium oxide.

[0011] A preparation method of the NO removal catalyst,

[0012] 1. carrier pretreatment: the carrier is calcined at 800℃ for 1-4 hours;

[0013] 2. the pretreated carrier is put into an ammonium metatungstate solution for saturated impregnation in equal volume, dried at 80-150℃ for 1-4 hours, and then calcined at 200-500℃ for 1-4 hours to obtain a catalyst intermediate;

[0014] 3. copper salt and nitrate of multi-metal oxide are mixed to prepare a mixed solution in water, and then the catalyst intermediate is added for saturated impregnation in equal volume, dried at 80-150℃ for 1-4 hours, and then calcined at 200-500℃ for 1-4 hours to obtain the NO removal catalyst; wherein the multi-metal oxide does not include tungsten.

[0015] The specific surface area of the pretreated active alumina ball is 100-250m 2 / g, the pore volume is 0.1-0.7cm 3 / g, the average pore size is 6-12nm, and the bulk specific gravity is 0.6-1.0g / ml.

[0016] The application of the NO removal catalyst.

[0017] The oxygen content in the reaction raw gas is 2%.

[0018] The reaction conditions of the catalyst are normal pressure, space velocity of 1000-10000h -1 , reaction temperature of 240-500℃, and the NO removal rate is more than 95%.

[0019] The catalyst is used for the NO removal reaction in the raw gas containing 2% of oxygen, and the experimental results show that the catalyst has good high-temperature NO removal activity, a wide reaction temperature range, and stable performance.

[0020] Compared with the prior art, the application has the following advantages:

[0021] The carrier of the catalyst is obtained by calcination at 800℃, the pore structure is suitable, the interaction between the active component and the additive is moderate, and the removal reaction of nitric oxide can be promoted; the catalyst of the application uses copper oxide as the active component, adds multi-metal oxide additive, and through the synergistic catalysis of the active component and the additive, the catalyst has good high-temperature NO removal effect; the catalyst of the application uses the impregnation method to carry the active component and the additive, and then is dried and calcined to obtain, the preparation process is simple, the operation is convenient, the operation temperature range is wide, the stability is high, and the industrial application can be realized on a large scale. DETAILED DESCRIPTION

[0022] The application will be further described in conjunction with the following specific examples, but the scope of the application is not limited thereto.

[0023] Example 1

[0024] 1. The alumina carrier was pretreated by placing it in a muffle furnace and calcining at 800°C for 4 hours;

[0025] 2. 4 g of ammonium metatungstate was dissolved in 46 g of water to form a salt solution. 100 g of the alumina carrier treated as above was immersed in the salt solution for 30 minutes, dried at 120°C for 3 hours, and then calcined at 400°C for 4 hours to obtain a catalyst intermediate;

[0026] 3. 13 g of copper nitrate, 7 g of iron nitrate, 2 g of samarium nitrate, and 0.6 g of zirconium nitrate were dissolved in 46 g of water to form a mixed solution. The catalyst intermediate was immersed in the mixed solution for 30 minutes, dried at 120°C for 3 hours, and then calcined at 400°C for 4 hours to obtain the catalyst, wherein the copper oxide content was 4.28%, the iron oxide content was 2.77%, the tungsten oxide content was 3.75%, the samarium oxide content was 0.68%, and the zirconium oxide content was 0.17%.

[0027] The activated alumina spheres obtained by the pretreatment had a specific surface area of 170 m 2 / g , a pore volume of 0.56 cm 3 / g , an average pore diameter of 7.88 nm, and a bulk specific gravity of 0.65 g / ml .

[0028] The activity of the catalyst was evaluated in a fixed bed reactor. The reactor was a stainless steel tube with an inner diameter of 9 mm, and the catalyst loading was 1.5 g. A NO analyzer was used to analyze the NO content of the outlet gas on line. The feed gas composition (V%) was: 1000 ppm NO, 1200 ppm NH3, and 2% O2 in N2.

[0029] The catalyst of Example 1 was subjected to the NO removal reaction at room temperature under normal pressure and a volume space velocity of 10000 h -1 . The outlet NO content was detected while slowly increasing the temperature. The results showed that when the NO removal rate was above 95%, the reaction temperature window was 250-470°C.

[0030] Example 2

[0031] 1. The alumina carrier was pretreated by placing it in a muffle furnace and calcining at 800°C for 4 hours;

[0032] 2. Weigh 2 g of ammonium metatungstate and dissolve it in 46 g of water to form a salt solution. Pour 100 g of the alumina carrier treated above into the salt solution and immerse for 30 minutes. Dry at 120°C for 3 hours and then calcine at 400°C for 4 hours to obtain a catalyst intermediate.

[0033] 3. Dissolve 18 g of copper nitrate, 8 g of iron nitrate and 2 g of cerium nitrate in 45 g of water to form a mixed solution. Pour the catalyst intermediate into the mixed solution and immerse for 30 minutes. Dry at 120°C for 3 hours and then calcine at 400°C for 4 hours to obtain the catalyst. The copper oxide content is 5.93%, the iron oxide content is 3.17%, the tungsten oxide content is 1.88% and the cerium oxide content is 0.79%.

[0034] The activated alumina spheres obtained by the pretreatment have a specific surface area of 165 m 2 / g , a pore volume of 0.53 cm 3 / g , an average pore diameter of 8.05 nm and a bulk specific gravity of 0.64 g / ml .

[0035] The activity of the catalyst was evaluated in a fixed bed reactor. The reactor was a stainless steel tube with an inner diameter of 9 mm and the catalyst loading was 1.52 g. A NO analyzer was used to analyze the NO content of the outlet gas on line. The composition of the raw gas was (V%): 1000 ppm NO, 1200 ppm NH3 and 2% O2 in N2.

[0036] The catalyst of Example 2 was subjected to the raw gas at room temperature and the NO removal reaction was carried out at normal pressure and a volume space velocity of 10000 h -1 . The outlet NO content was detected while the temperature was slowly increased. The results show that when the NO removal rate is above 95%, the reaction temperature window is 250-500°C.

[0037] Example 3

[0038] 1. The alumina carrier was pretreated by placing it in a muffle furnace and calcining at 800°C for 4 hours.

[0039] 2. Weigh 2 g of ammonium metatungstate and dissolve it in 46 g of water to form a salt solution. Pour 100 g of the alumina carrier treated above into the salt solution and immerse for 30 minutes. Dry at 120°C for 3 hours and then calcine at 400°C for 4 hours to obtain a catalyst intermediate.

[0040] 3. Dissolve 20 g of copper nitrate, 3 g of samarium nitrate and 2 g of cerium nitrate in 46 g of water to form a mixed solution, immerse the catalyst intermediate in the mixed solution for 30 minutes, dry at 120°C for 3 hours, and then calcine at 400°C for 4 hours to obtain the catalyst, wherein the copper oxide content is 6.59%, the samarium oxide content is 1.02%, the tungsten oxide content is 4.7%, and the cerium oxide content is 0.79%.

[0041] The activated alumina balls obtained by the pretreatment have a specific surface area of 170 m 2 / g , a pore volume of 0.57 cm 3 / g , an average pore diameter of 7.65 nm, and a bulk specific gravity of 0.60 g / ml .

[0042] The activity evaluation of the catalyst was performed in a fixed bed reactor. The reactor was a stainless steel tube with an inner diameter of 9 mm, and the catalyst loading was 1.52 g. A NO analyzer was used to analyze the NO content of the outlet gas on line. The raw gas composition (V%) was: 1000 ppm of NO, 1200 ppm of NH3, and 2% of O2 in N2.

[0043] The catalyst in Example 3 was subjected to the raw gas at room temperature, and the NO removal reaction was performed at normal pressure and a volume space velocity of 10000 h -1 . The outlet NO content was detected while slowly increasing the temperature. The results show that when the NO removal rate is above 96%, the reaction temperature window is 270-470°C.

[0044] Example 4

[0045] 1. Pretreat the alumina carrier by placing the alumina carrier in a muffle furnace and calcining at 800°C for 4 hours;

[0046] 2. Weigh 3 g of ammonium metatungstate, dissolve it in 46 g of water to form a salt solution, immerse 100 g of the alumina carrier obtained by the above treatment in the salt solution for 30 minutes, dry at 120°C for 3 hours, and then calcine at 400°C for 4 hours to obtain the catalyst intermediate;

[0047] 3. Dissolve 10 g of copper nitrate, 8 g of iron nitrate and 1.5 g of zirconium nitrate in 46 g of water to form a mixed solution, immerse the catalyst intermediate in the mixed solution for 30 minutes, dry at 120°C for 3 hours, and then calcine at 400°C for 4 hours to obtain the catalyst, wherein the copper oxide content is 3.29%, the iron oxide content is 3.17%, the tungsten oxide content is 2.82%, and the zirconium oxide content is 0.43%.

[0048] The activated alumina balls obtained by the pretreatment have a specific surface area of 168 cm2 g , pore volume 0.58 m 3 g , average pore diameter 7.29 nm, bulk density 0.63 g / cm3 ml .

[0049] The activity of the catalyst was evaluated in a fixed bed reactor. The reactor was a stainless steel tube with an inner diameter of 9 mm, and the catalyst loading was 1.52 g. The NO content of the outlet gas was analyzed on-line using a NO analyzer. The feed gas composition (V %) was: 1000 ppm NO, 1200 ppm NH3, 2% O2 in N2.

[0050] The catalyst of Example 4 was used to remove NO at room temperature under normal pressure and a volume space velocity of 10000 h -1 -1. Slowly increasing the temperature, and detecting the NO content of the outlet gas. The results showed that when the NO removal rate was above 96%, the reaction temperature window was 240-480°C.

[0051] Example 5

[0052] This example shows the 220-hour life test results of the catalyst of the present application. The activity was evaluated in a fixed bed reactor. The reactor was a stainless steel tube with an inner diameter of 9 mm, and the catalyst loading was 1.52 g. The NO content of the outlet gas was analyzed on-line using a NO analyzer. The feed gas composition (V %) was: 1000 ppm NO, 1200 ppm NH3, 2% O2 in N2.

[0053] The catalyst of Example 4 was used to remove NO at room temperature under normal pressure and a volume space velocity of 10000 h -1 -1. Slowly increasing the temperature, and detecting the NO content of the outlet gas. The results showed that when the NO removal rate was above 95%, the reaction temperature window was 240-480°C.

[0054] The life test results showed that the catalyst had good medium-high temperature NO removal activity and stability.

[0055] Comparative Example 1

[0056] The difference between this example and Example 4 was that the alumina carrier was not pretreated, and the rest of the preparation method was the same as that of Example 4. Specifically:

[0057] ​​1. Weigh 3 g of ammonium metatungstate and dissolve it in 46 g of water to form a salt solution. Pour 100 g of alumina balls into the salt solution and immerse for 30 minutes. Dry at 120°C for 3 hours and then calcine at 400°C for 4 hours to obtain a catalyst intermediate.

[0058] 2. Dissolve 10 g of copper nitrate, 8 g of iron nitrate and 1.5 g of zirconium nitrate in 46 g of water to form a mixed solution. Pour the catalyst intermediate into the mixed solution and immerse for 30 minutes. Dry at 120°C for 3 hours and then calcine at 400°C for 4 hours to obtain the catalyst, which contains 3.29% of copper oxide, 3.17% of iron oxide, 2.82% of tungsten oxide and 0.43% of zirconium oxide.

[0059] The alumina balls have a specific surface area of 350 m 2 / g , a pore volume of 0.73 cm 3 / g , an average pore diameter of 5.15 nm and a bulk specific gravity of 0.52 g / ml .

[0060] The activity of the catalyst was evaluated in a fixed bed reactor. The reactor was a stainless steel tube with an inner diameter of 9 mm and the catalyst loading was 1.52 g. A NO analyzer was used to analyze the NO content of the outlet gas on line. The composition of the raw gas was (V%): 1000 ppm of NO, 1200 ppm of NH3 and 2% of O2 in N2.

[0061] The catalyst was fed with the raw gas at room temperature and the NO removal reaction was carried out at normal pressure and a volume space velocity of 10000 h -1 . The outlet NO content was detected while the temperature was slowly increased. The results show that the highest NO removal rate is 90% and the corresponding reaction temperature window is 270-330°C.

[0062] The activity of the catalyst of Example 4 was compared with that of the catalyst of Example 2. It can be seen that, under the same catalyst components and contents, the alumina carrier calcined at 800°C can effectively improve the NO removal activity of the catalyst.

[0063] Comparative Example 2

[0064] The difference between Example 4 and Comparative Example 2 is that only the active component copper is impregnated and the rest of the preparation method is the same as that of Example 4. Specifically:

[0065] 1. The alumina carrier was pretreated by placing it in a muffle furnace and calcining at 800°C for 4 hours.

[0066] 2. 10 g of copper nitrate is weighed and dissolved in 47 g of water to form a salt solution. 100 g of the alumina carrier treated above is dipped in the salt solution for 30 minutes, dried at 120°C for 3 hours, and calcined at 400°C for 4 hours to obtain the catalyst, wherein the copper oxide content is 3.29%.

[0067] The activated alumina ball obtained by the pretreatment has a specific surface area of 167 m 2 / g , a pore volume of 0.58 m 3 / g , an average pore diameter of 7.19 nm, and a bulk specific gravity of 0.65 g / ml .

[0068] The activity of the catalyst is evaluated in a fixed bed reactor. The reactor is a stainless steel tube with an inner diameter of 9 mm, and the catalyst loading is 1.52 g. A NO analyzer is used to analyze the NO content of the outlet gas on line. The feed gas composition (V%) is: 1000 ppm of NO, 1200 ppm of NH3, and 2% of O2 in N2.

[0069] The catalyst is fed with the feed gas at room temperature, and the NO removal reaction is carried out at normal pressure and a volume space velocity of 10000 h -1 . The outlet NO content is detected while the temperature is slowly increased. The results show that when the NO removal rate is above 90%, the reaction temperature window is 240-340°C.

[0070] Compared with the activity of the catalyst in Example 4, it can be seen that the reaction temperature window of the single-component copper oxide catalyst is narrow when the NO removal rate is above 90%, and the high-temperature NO removal activity is low. The addition of the multi-component additive greatly improves the high-temperature NO removal activity of the catalyst. Through the synergistic effect of the active component and the multi-component additive, the catalyst has good high-temperature NO removal performance.

[0071] Through the activity comparison of the catalysts in the above comparative examples and examples, it is found that due to the interaction among the carrier, the active component and the multi-component additive, the catalyst in the present application has the characteristics of good high-temperature NO removal activity, wide temperature range and stable performance, and has good industrial application prospect.

Claims

1. A catalyst for the removal of NO, characterized in that: The catalyst comprises an active component, an auxiliary agent and a carrier, wherein the active component is copper oxide, the auxiliary agent is a multi-metal oxide, and the carrier is active alumina ball; the active component accounts for 3-10% of the weight of the carrier, and the auxiliary agent accounts for 3-10% of the weight of the carrier; The multi-metal oxide is iron oxide, tungsten oxide, samarium oxide or zirconium oxide; Or the multi-metal oxide is iron oxide, tungsten oxide or cerium oxide; Or the multi-metal oxide is samarium oxide, tungsten oxide or cerium oxide; Or the multi-metal oxide is iron oxide, tungsten oxide or zirconium oxide; The carrier is pretreated by calcining at 800 DEG C for 1-4 hours.

2. A preparation method of the NO removal catalyst according to claim 1, characterized in that: (1) the carrier is pretreated by calcining at 800 DEG C for 1-4 hours; (2) the pretreated carrier is saturatedly impregnated in an equal volume of an ammonium metatungstate solution, dried at 80-150 DEG C for 1-4 hours, and calcined at 200-500 DEG C for 1-4 hours to obtain a catalyst intermediate; (3) copper salt and nitrate of multi-metal oxide are mixed to prepare a mixed solution, and then the catalyst intermediate is saturatedly impregnated in the mixed solution, dried at 80-150 DEG C for 1-4 hours, and calcined at 200-500 DEG C for 1-4 hours to obtain the NO removal catalyst; The multi-metal oxide does not include tungsten.

3. The method for preparing the NO removal catalyst according to claim 2, characterized in that: The activated alumina ball after the pretreatment has a specific surface area of 100-250 m 2 / g, a pore volume of 0.1-0.7 cm 3 / g, an average pore diameter of 6-12 nm, and a bulk specific gravity of 0.6-1.0 g / ml.

4. Use of a catalyst for the removal of NO according to claim 1, characterized in that: The application of the catalyst in the NO removal reaction.

5. Use of a catalyst according to claim 4 for the removal of NO, characterized in that: The oxygen content in the reaction raw gas is 2%.

6. Use of a NO removal catalyst according to claim 4, characterized in that: The reaction conditions of the catalyst are normal pressure, space velocity 1000-10000h -1 , and reaction temperature 240-500°C.