Selective catalytic oxidation catalysts for nitrogen-containing vocs and methods of making and using the same

Abstract

The present application relates to the technical field of nitrogen-containing VOCs treatment, and discloses a selective catalytic oxidation catalyst for nitrogen-containing VOCs and a preparation method thereof.The method comprises the following steps: 1) sequentially performing first contact and first calcination on a solution containing a first active component and a porous carrier to obtain a first calcination product; and 2) sequentially performing second contact and second calcination on a solution containing a second active component and the first calcination product, wherein the first active component is one or more of Mn, Fe, Co and Cu, and the second active component is Pt and / or Pd; the first contact is performed so that the content of the first active component in the prepared catalyst is 3-10 wt.%, and the second contact is performed so that the content of the second active component in the prepared catalyst is 0.5-3 wt.%. The catalyst provided by the present application can directly convert the nitrogen element in the nitrogen-containing VOCs into N2, achieving the balance between high conversion rate of the nitrogen-containing VOCs and high selectivity of N2.

Description

Technical Field

[0001] This invention relates to the field of nitrogen-containing VOCs treatment technology, specifically to a selective catalytic oxidation catalyst for nitrogen-containing VOCs and its preparation method, as well as a method for treating nitrogen-containing VOCs. Background Technology

[0002] Volatile organic compounds (VOCs) refer to easily volatile organic compounds with boiling points between 50-260℃ and saturated vapor pressures exceeding 133.3 Pa at room temperature. As important precursors to secondary aerosols, VOCs contribute to the generation of air pollutants (ozone, particulate matter, etc.) and are a significant contributor to current regional atmospheric complex pollution. VOC emissions are particularly prominent in industries such as petrochemicals, electronics, printing, coatings, paints, and food and feed processing.

[0003] VOCs mainly include conventional aliphatic hydrocarbons, oxygenated hydrocarbons, aromatic hydrocarbons and their derivatives, and hydrocarbons containing heteroatoms (Cl, S, N, etc.). Nitrogen-containing VOCs, which are heteroatom-containing volatile organic compounds, mainly include amines, amides, nitriles, and nitro hydrocarbons, and are widely present in various industrial processes. Nitrogen-containing VOCs often have a pungent and irritating odor and are more harmful to human health than conventional volatile organic compounds. Therefore, efficient emission reduction and control of nitrogen-containing VOCs is of great significance for improving air quality.

[0004] Catalytic oxidation is a highly efficient and clean method for treating VOCs, converting conventional VOCs into non-toxic carbon dioxide and water. However, for nitrogen-containing VOCs, simple catalytic oxidation will oxidize most of the nitrogen to NO. x (NO, NO2 and N2O). NO x Nitrogenous VOCs are another major type of air pollutant, causing severe air pollution such as acid rain and smog. Therefore, for the treatment of nitrogen-containing VOCs, after the catalytic oxidation process, further measures are often needed to eliminate NO. x This greatly increases the complexity and operating cost of the exhaust gas treatment system.

[0005] Therefore, various fields are actively seeking methods to selectively and directly convert nitrogen-containing VOCs into N2.

[0006] For example, CN103212419A discloses a catalyst for treating acrylonitrile (C3H3N)-containing waste gas, its preparation method, and its application. This catalyst uses a perovskite crystal material with an ABO3 structure, and through specific reaction conditions, acrylonitrile is primarily converted into CO2, H2O, and N2. However, when the O2 content in the reaction atmosphere increases, the N2 selectivity of this catalyst decreases significantly, increasing the difficulty of treating flue gas with high O2 content.

[0007] CN109289911A discloses a catalyst and method for treating nitrogen-containing volatile organic compounds (VOCs). The catalyst includes a supported catalyst or a hydrotalcite-derived composite oxide catalyst. The supported catalyst uses a molecular sieve or a cerium-zirconium solid solution as its support, and a transition metal as its active component. The hydrotalcite-derived composite oxide catalyst is an oxide material containing Cu, Mg, Co, Ni, Al, Mn, and Fe. However, when this catalyst is used to treat nitrogen-containing VOCs, it requires a high catalytic reaction temperature and consumes a lot of energy, which is very unfavorable for industrial applications. Furthermore, this catalyst is ineffective in oxidizing n-butylamine (C4H4H2O). 11 When N), the selectivity of N2 is still insufficient, and NO exists. x In cases of high emissions, reducing agents are also needed to counteract NO. x Further catalytic reduction treatment is carried out.

[0008] On the other hand, in actual production, flue gas operating conditions are often quite complex. For example, there may be large fluctuations in flue gas temperature, high oxygen content in flue gas, and high moisture content. This complex environment also makes it more difficult to effectively eliminate nitrogen-containing VOCs.

[0009] Therefore, there is an urgent need to develop a highly efficient selective catalytic oxidation catalyst for nitrogen-containing VOCs to efficiently convert nitrogen-containing VOCs under conditions of wide temperature range and high oxygen content. Summary of the Invention

[0010] The purpose of this invention is to overcome the limitations of existing technologies in treating nitrogen-containing VOCs, which are complex and generate NO during the treatment process. x This invention addresses these issues by providing a selective catalytic oxidation catalyst for nitrogen-containing VOCs, its preparation method, and its applications, as well as a method for treating nitrogen-containing VOCs. The catalyst and method provided by this invention can directly convert nitrogen in nitrogen-containing VOCs into N2, with almost no NO production during the catalytic process. x This catalyst not only achieves a balance between high conversion rate of nitrogen-containing VOCs and high selectivity of N2 over a wide temperature window, but also ensures excellent catalytic performance for gases with high water vapor and oxygen content.

[0011] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a nitrogen-containing VOCs selective catalytic oxidation catalyst, the method comprising the following steps:

[0012] 1) A solution containing the first active component is subjected to a first contact and a first calcination with a porous support in sequence to obtain a first calcination product;

[0013] 2) The solution containing the second active component is subjected to a second contact and a second calcination with the first calcined product in sequence.

[0014] Wherein, the first active component is one or more of Mn, Fe, Co and Cu, and the second active component is Pt and / or Pd;

[0015] The first contact ensures that, in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst, the content of the first active component, based on elemental metal, is 3-10% by weight.

[0016] The second contact results in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst having a content of 0.5-3% by weight, based on elemental metal.

[0017] Preferably, the porous support is one or more of ZSM-5 molecular sieve, β-type molecular sieve, SAPO-34 molecular sieve, Y-type molecular sieve and SSZ-13 molecular sieve; more preferably, the porous support is ZSM-5 molecular sieve and / or SSZ-13 molecular sieve; even more preferably, the porous support is ZSM-5 molecular sieve.

[0018] Preferably, the first active component is Fe and / or Cu, more preferably Cu.

[0019] Preferably, the first contact is such that in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst, the content of the first active component, based on elemental metal, is 4-6% by weight.

[0020] Preferably, the second active component is Pd.

[0021] Preferably, the second contact is such that, in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst, the content of the second active component, based on elemental metal, is 1-2% by weight.

[0022] Preferably, the conditions for the first roasting include: a temperature of 300-800℃ and a time of 2-24h; more preferably, the conditions for the first roasting include: a temperature of 450-700℃ and a time of 4-8h.

[0023] Preferably, the conditions for the second roasting include: a temperature of 300-800℃ and a time of 2-24h; more preferably, the conditions for the second roasting include: a temperature of 450-700℃ and a time of 4-8h.

[0024] Preferably, the preparation method further includes a drying step before the first calcination and the second calcination.

[0025] The second aspect of the present invention provides a nitrogen-containing VOCs selective catalytic oxidation catalyst prepared by the preparation method described in the first aspect of the present invention.

[0026] The third aspect of the present invention provides the application of the nitrogen-containing VOCs selective catalytic oxidation catalyst described in the second aspect of the present invention in the treatment of nitrogen-containing VOCs.

[0027] The fourth aspect of the present invention provides a method for treating nitrogen-containing VOCs in a gas, the method comprising: contacting the gas to be treated with the nitrogen-containing VOCs selective catalytic oxidation catalyst described in the second aspect of the present invention.

[0028] Preferably, the contact conditions include: a contact temperature of 250-550°C and a volume hourly space velocity of 2,000-300,000 h⁻¹. -1 The flow rate of the gas to be treated is 100-5,000 mL / min; more preferably, the contact conditions include: a contact temperature of 275-450°C and a volume hourly space velocity of 5,000-150,000 h⁻¹. -1 The flow rate of the gas to be treated is 200-3,000 mL / min.

[0029] Preferably, the nitrogen-containing VOCs are one or more of ethylenediamine, diethylamine, n-butylamine, monoethanolamine, diethanolamine, acrylonitrile, aniline and nitrobenzene, more preferably monoethanolamine.

[0030] Preferably, the concentration of nitrogen-containing VOCs in the gas to be treated is 10-10,000 ppm, more preferably 100-2,000 ppm.

[0031] Preferably, the contact results in a conversion rate of nitrogen-containing VOCs of 95% or higher, more preferably 98% or higher.

[0032] Preferably, the contact results in an N2 selectivity of 95% or more, more preferably 98% or more.

[0033] The method for preparing a nitrogen-containing VOCs selective catalytic oxidation catalyst provided by this invention enables at least a portion of the first active component to first enter the interior of the porous support channels (i.e., the inner surface of the porous support) to form reduction sites, and the second active component to be loaded on the surface of the porous support (i.e., the outer surface of the porous support) to form oxidation sites. Furthermore, the remaining first active component can also be loaded on the surface of the porous support. Through the synergistic effect of the specific first and second active components, nitrogen-containing intermediates can be selectively and in-situ reduced to N2 while oxidizing nitrogen-containing VOCs. Therefore, NO2 can be avoided. x The generation of.

[0034] The nitrogen-containing VOCs selective catalytic oxidation catalyst prepared by the method described in this invention can achieve a conversion rate of over 95% for nitrogen-containing VOCs and a selectivity for N2 of over 95%, demonstrating excellent performance. It significantly reduces the processing steps for nitrogen-containing VOCs and improves processing efficiency, while also substantially saving energy and processing costs.

[0035] Furthermore, the nitrogen-containing VOCs selective catalytic oxidation catalyst has a wide temperature window, enabling it to treat complex gases with high oxygen and water vapor content, making it highly suitable for industrial applications. Attached Figure Description

[0036] Figure 1 This is an activity curve of the nitrogen-containing VOCs selective catalytic oxidation catalysts prepared in Examples 1, 4 and 5 of this invention for the catalytic oxidation of monoethanolamine;

[0037] Figure 2 This is a graph showing the N2 selectivity curves of the nitrogen-containing VOCs selective catalytic oxidation catalysts prepared in Examples 1, 4 and 5 of this invention for the catalytic oxidation of monoethanolamine.

[0038] Figure 3 This is an activity curve of the nitrogen-containing VOCs selective catalytic oxidation catalyst prepared in Comparative Examples 1-3 of this invention for the catalytic oxidation of monoethanolamine;

[0039] Figure 4 This is a graph showing the N2 selectivity of the nitrogen-containing VOCs selective catalytic oxidation catalysts prepared in Comparative Examples 1-3 of this invention for the catalytic oxidation of monoethanolamine.

[0040] Figure 5 This is a long-term stability test activity curve of the nitrogen-containing VOCs selective catalytic oxidation catalyst prepared in Example 1 of the present invention for the catalytic oxidation of monoethanolamine;

[0041] Figure 6This is an N2 selectivity curve for the long-term stability test of the nitrogen-containing VOCs selective catalytic oxidation catalyst prepared in Example 1 of this invention for the catalytic oxidation of monoethanolamine. Detailed Implementation

[0042] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0043] A first aspect of the present invention provides a method for preparing a nitrogen-containing VOCs selective catalytic oxidation catalyst, wherein the method includes the following steps:

[0044] 1) A solution containing the first active component is subjected to a first contact and a first calcination with a porous support in sequence to obtain a first calcination product;

[0045] 2) The solution containing the second active component is subjected to a second contact and a second calcination with the first calcined product in sequence.

[0046] Wherein, the first active component is one or more of Mn, Fe, Co and Cu, and the second active component is Pt and / or Pd; the first contact causes the content of the first active component in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst to be 3-10% by weight, based on the metal element; and the second contact causes the content of the second active component in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst to be 0.5-3% by weight, based on the metal element.

[0047] During their long-term research, the inventors of this invention unexpectedly discovered that by first impregnating a porous support with the first active component and then calcining it, the first active component can be filled and fixed inside the pores of the support, forming reduction sites. Furthermore, by controlling the impregnation amount of the first active component within a specific range, the remaining first active component after entering the pores can be loaded onto the surface of the porous support. Subsequently, by loading a second active component and calcining it, the second active component is loaded onto the surface of the porous support, forming oxidation sites on the surface. Thus, by forming specific reduction and oxidation sites at specific locations on the porous support, the prepared selective catalytic oxidation catalyst for nitrogen-containing VOCs can simultaneously achieve in-situ oxidation and reduction when in contact with nitrogen-containing VOCs, thereby converting nitrogen in nitrogen-containing VOCs into N2 in situ and avoiding undesirable NO. x The generation of.

[0048] According to a first aspect of the invention, the porous support is not particularly limited, but is preferably a variety of molecular sieves commonly found in the art.

[0049] To further improve the catalytic activity of the catalyst, the porous support is more preferably one or more of ZSM-5 molecular sieve, β-type molecular sieve, SAPO-34 molecular sieve, Y-type molecular sieve and SSZ-13 molecular sieve, and more preferably ZSM-5 molecular sieve and / or SSZ-13 molecular sieve.

[0050] Furthermore, in a particularly preferred embodiment of the present invention, the support is a ZSM-5 molecular sieve. The inventors of the present invention have discovered that by using a ZSM-5 molecular sieve as the support for the catalyst described in the present invention, the conversion rate of nitrogen-containing VOCs can be further improved.

[0051] According to the preparation method of the nitrogen-containing VOCs selective catalytic oxidation catalyst of the first aspect of the present invention, a solution containing a first active component is first contacted with a porous support, and the first contact product is first calcined. This allows the first active component to fully enter and immobilize within the pores of the porous support, forming reduction sites. Furthermore, by controlling the content of the first active component during the first contact, a portion of the first active component can be loaded onto the surface of the porous support after calcination, forming specific oxidation sites, ultimately converting nitrogen in nitrogen-containing VOCs into N2.

[0052] According to the present invention, the first active component is one or more of Mn, Fe, Co and Cu, wherein, preferably, the first active component is Fe and / or Cu, more preferably Cu.

[0053] During the research process, the inventors of this invention discovered that when Cu is used as the first active component of the catalyst, it can better exert the reduction effect and better synergize with the second active component, thereby significantly improving the conversion rate of nitrogen-containing VOCs and greatly improving the selectivity of N2.

[0054] In the catalyst described in this invention, the content of the first active component is crucial.

[0055] In this invention, it is desirable not only that a portion of the first active component exists within the pores of the porous support to form reduction sites, but also that at least a portion of the first active component exists on the surface of the porous support. This can further significantly enhance the synergistic effect of the first and second active components, better realize the distribution and regulation of reduction and oxidation sites, and thereby further improve the nitrogen-containing VOCs conversion rate and N2 selectivity of the catalyst.

[0056] Therefore, in step 1), the first contact ensures that the content of the first active component in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst is 3-10% by weight, based on elemental composition.

[0057] Furthermore, the inventors of this invention have discovered that if the first active component is below the above-mentioned content, the catalytic performance of the catalyst will be greatly weakened, reducing the conversion rate of nitrogen-containing VOCs and the N2 selectivity; if it is above this content, the N2 selectivity will be reduced instead.

[0058] In addition, in step 1), preferably, the first contact ensures that the content of the first active component in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst is 4-6% by weight, based on elemental composition. When the content of the first active component is within the above range, the conversion rate of nitrogen-containing VOCs and N2 selectivity can be significantly improved, resulting in excellent catalytic performance.

[0059] Furthermore, in this invention, there are no particular restrictions on the content of the first active component in the solution containing the first active component during the first contact, or on the ratio of the solution containing the first active component to the porous support. These can be conventional choices in the art, as long as the first contact enables the content of the first active component, calculated as metal element, in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst to be 3-10% by weight.

[0060] For example, in the solution containing the first active component, the content of the first active component, based on the elemental metal, can be 0.5-10% by weight, preferably 1-5% by weight.

[0061] The weight ratio of the solution containing the first active component to the porous carrier can be, for example, 1:0.1-1, preferably 1:0.3-0.6.

[0062] Furthermore, in this invention, there are no particular limitations on the conditions for the first calcination. For example, the conditions for the first calcination may include: a temperature of 300-800°C and a time of 2-24 hours.

[0063] However, the inventors of this invention discovered through research that if the first calcination temperature is too low or the time is too short, the first active component will have difficulty diffusing into the molecular sieve channels, resulting in poor catalytic performance; if the first calcination temperature is too high or the time is too long, the structure of the support will collapse, leading to poor NO catalytic performance. x The sites for selective catalytic reduction can be destroyed, which in turn reduces catalytic performance.

[0064] Therefore, preferably, the conditions for the first calcination include: a temperature of 450-700℃ and a time of 4-8h.

[0065] Furthermore, in this invention, after the first calcination and before the second contact, a step of cooling the obtained first calcined product is included. The cooling can be any of the cooling methods conventionally used in the art, such as natural cooling, and can be cooled to room temperature (20-45°C), which is well known in the art and will not be elaborated here.

[0066] Next, the solution containing the second active component is brought into a second contact with the first calcined product to obtain a second contact product, which is then subjected to a second calcination. This step allows the second active component to be loaded onto the support surface, thereby synergistically interacting with the first active component to improve VOCs conversion rate and N2 selectivity.

[0067] According to the present invention, the second active component is Pt and / or Pd, preferably Pd. When Pd is used as the second active component of the selective catalytic oxidation catalyst for nitrogen-containing VOCs, the conversion rate of nitrogen-containing VOCs can be significantly improved, while the selectivity of N2 can be greatly enhanced.

[0068] Furthermore, the second contact ensures that, in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst, the content of the second active component, based on elemental metal, is 0.5-3% by weight, preferably 1-2% by weight.

[0069] By controlling the content of the second active component within the above-mentioned preferred range through the second contact, the synergistic effect with the first active component can be further enhanced, thereby further improving the catalytic performance of the catalyst.

[0070] Furthermore, in this invention, there are no particular limitations on the content of the second active component in the solution containing the second active component during the second contact, nor on the ratio of the solution containing the second active component to the first calcined product. These can be conventional choices in the art, as long as the second contact enables the content of the second active component, calculated as metal element, in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst to be 0.5-3% by weight.

[0071] For example, in the solution containing the second active component, the content of the second active component, based on the metal element, can be 0.1-5% by weight, preferably 0.3-3% by weight.

[0072] The weight ratio of the solution containing the second active component to the porous carrier can be, for example, 1:0.1-1, preferably 1:0.2-0.6.

[0073] In this invention, there are no particular limitations on the conditions for the second calcination. For example, the conditions for the second calcination may include: a temperature of 300-800℃ and a time of 2-24h; preferably, the conditions for the second calcination include: a temperature of 450-700℃ and a time of 4-8h.

[0074] In addition to the steps described above, in this invention, preferably, the first contact product or the second contact product is dried before the first calcination and the second calcination.

[0075] Here, the drying conditions are not particularly limited and can be conventional drying conditions in the art. For example, the drying temperature can be 90-120°C, the time can be 4-48 hours, and the drying method is also a conventional method in the art, which will not be described in detail here.

[0076] A second aspect of the present invention provides a nitrogen-containing VOCs selective catalytic oxidation catalyst prepared by the method described in the first aspect of the present invention.

[0077] According to a second aspect of the present invention, the catalyst comprises a porous support and a first active component and a second active component supported on the porous support, wherein the first active component is one or more of Mn, Fe, Co and Cu, preferably Cu; the second active component is Pt and / or Pd, preferably Pd; and the content of the first active component, based on the elemental metal, is 3-10% by weight, preferably 4-6% by weight, and the content of the second active component is 0.5-3% by weight, preferably 1-2% by weight.

[0078] In a particularly preferred embodiment of the present invention, the first active component is Cu, and the second active component is Pd, while ZSM-5 molecular sieve is selected as the porous support. This allows the nitrogen-containing VOCs selective catalytic oxidation catalyst to possess excellent conversion rates of nitrogen-containing VOCs and N2 selectivity, making it highly suitable for the treatment of nitrogen-containing VOCs.

[0079] The third aspect of the present invention provides the application of the nitrogen-containing VOCs selective catalytic oxidation catalyst described in the second aspect of the present invention in the treatment of nitrogen-containing VOCs.

[0080] The inventors of this invention have discovered that when the selective catalytic oxidation catalyst for nitrogen-containing VOCs described in the second aspect of this invention is applied to the treatment of nitrogen-containing VOCs, the synergistic effect of the first and second active components in specific amounts and types can simultaneously provide specific oxidation and reduction sites. This allows for the selective in-situ reduction of intermediate products to N2 while oxidizing nitrogen-containing VOCs, thus avoiding the oxidation of NO. x The generation of.

[0081] Therefore, the method provided by this invention can also avoid the need for further NO removal after oxidation treatment in conventional technologies when treating nitrogen-containing VOCs. x This invention addresses the issue of emissions. It significantly reduces the complexity and cost of the treatment process. Furthermore, the nitrogen-containing VOCs selective catalytic oxidation catalyst provided by this invention achieves a conversion rate of over 95% for nitrogen-containing VOCs and a selectivity for N2 of over 95%, demonstrating excellent performance.

[0082] In addition, the nitrogen-containing VOCs selective catalytic oxidation catalyst of the present invention has a wide temperature window and can be used to treat complex gases with high oxygen and water vapor content, making it very suitable for industrial applications.

[0083] The fourth aspect of the present invention provides a method for treating nitrogen-containing VOCs in a gas, wherein the method includes: contacting the gas to be treated with the nitrogen-containing VOCs selective catalytic oxidation catalyst described in the second aspect of the present invention.

[0084] According to a fourth aspect of the present invention, by contacting a gas containing nitrogen-containing VOCs with the catalyst described in the second aspect of the present invention, the nitrogen-containing VOCs in the gas to be treated can be oxidized to produce NO. x And at the same time, the generated NO x It is further reduced to N2 in situ, with almost no NO emission. x .

[0085] In this invention, the nitrogen-containing VOCs in the gas to be treated are not particularly limited and can be various nitrogen-containing VOCs commonly found in the art. For example, the nitrogen-containing VOCs can be one or more of ethylenediamine, diethylamine, n-butylamine, monoethanolamine, diethanolamine, acrylonitrile, aniline, and nitrobenzene. Preferably, the nitrogen-containing VOCs are monoethanolamine.

[0086] In addition, the concentration of nitrogen-containing VOCs in the gas to be treated is not particularly limited in this invention. For example, it can be 10-10,000 ppm, preferably 100-2,000 ppm.

[0087] In this invention, there is no particular limitation on the location of the contact; any conventional choice in the art can be used. Preferably, the contact takes place within a fixed-bed reactor.

[0088] Furthermore, there are no particular limitations on the contact conditions. For example, the contact conditions may include: a reaction temperature of 250-550°C and a volume hourly space velocity of 2,000-300,000 h⁻¹. -1The flow rate of the gas to be treated is 100-5,000 mL / min; preferably, the contact conditions include: a reaction temperature of 275-450 °C and a volume hourly space velocity of 5,000-150,000 h⁻¹. -1 The flow rate of the gas to be treated is 200-3,000 mL / min. By conducting the contact under the above conditions, the conversion rate of nitrogen-containing VOCs and the selectivity of N2 can be further improved.

[0089] The method described in the fourth aspect of the present invention can be used to treat gases containing nitrogen-containing VOCs, such that the conversion rate of nitrogen-containing VOCs is 95% or more, preferably 98% or more.

[0090] Furthermore, the method described in the fifth aspect of the present invention can achieve an N2 selectivity of 95% or more, preferably 98% or more, in a gas containing nitrogen-containing VOCs.

[0091] The present invention will be described in detail below through embodiments, but the present invention is not limited to the following embodiments.

[0092] In the following examples, unless otherwise specified, all raw materials used are commercially available products or prepared using conventional methods.

[0093] Example 1

[0094] 1) Add 20.50g of copper nitrate trihydrate to 200g of deionized water and stir until the copper nitrate trihydrate is fully dissolved to obtain the first impregnation solution;

[0095] 2) Mix the first impregnation solution obtained in step 1) with 100g of ZSM-5 molecular sieve support, stir and impregnate at 25°C for 60min, and then heat at 90°C for 120min to obtain the first impregnation product.

[0096] 3) The first impregnated product was placed in a forced-air drying oven and dried at 110°C for 12 hours. Then it was transferred to a muffle furnace and calcined at 550°C for 5 hours. After that, it was naturally cooled to room temperature to obtain the first calcined product.

[0097] 4) Add 7.19g of palladium nitrate solution (calculated as palladium, with a palladium content of 15% by weight, the same below) to 200g of deionized water, stir well, and obtain the second impregnation solution;

[0098] 5) Mix the second impregnation liquid obtained in step 4) with the first calcination product obtained in step 3), stir and impregnate at 25°C for 60 min, and then heat at 90°C for 120 min to obtain the second impregnation product.

[0099] 6) The second impregnation product was placed in a forced-air drying oven and dried at 110°C for 12 hours. Then it was transferred to a muffle furnace and calcined at 550°C for 5 hours. After that, it was naturally cooled to room temperature to obtain catalyst A1.

[0100] In catalyst A1, the Cu content is 5% by weight and the Pd content is 1% by weight, based on elemental metals.

[0101] Example 2

[0102] 1) Add 25.07g of copper nitrate trihydrate to 200g of deionized water and stir until the copper nitrate trihydrate is fully dissolved to obtain the first impregnation solution;

[0103] 2) Mix the first impregnation solution obtained in step 1) with 100g of ZSM-5 molecular sieve support, stir and impregnate at 25°C for 60min, and then heat at 90°C for 120min to obtain the first impregnation product.

[0104] 3) The first impregnated product was placed in a forced-air drying oven and dried at 110°C for 12 hours. Then it was transferred to a muffle furnace and calcined at 450°C for 8 hours. After that, it was naturally cooled to room temperature to obtain the first calcined product.

[0105] 4) Add 10.99g of palladium nitrate solution to 200g of deionized water and stir well to obtain the second impregnation solution;

[0106] 5) Mix the second impregnation liquid obtained in step 4) with the first calcination product obtained in step 3), stir and impregnate at 25°C for 60 min, and then heat at 90°C for 120 min to obtain the second impregnation product.

[0107] 6) The second impregnation product was placed in a forced-air drying oven and dried at 110°C for 12 hours. Then it was transferred to a muffle furnace and calcined at 700°C for 4 hours. After that, it was naturally cooled to room temperature to obtain catalyst A2.

[0108] In catalyst A2, the content of Cu is 6 wt% and the content of Pd is 1.5 wt%, based on elemental metals.

[0109] Example 3

[0110] 1) Add 16.36g of copper nitrate trihydrate to 200g of deionized water and stir until the copper nitrate trihydrate is fully dissolved to obtain the first impregnation solution;

[0111] 2) Mix the first impregnation solution obtained in step 1) with 100g of ZSM-5 molecular sieve support, stir and impregnate at 25°C for 60min, and then heat at 90°C for 120min to obtain the first impregnation product.

[0112] 3) The first impregnated product was placed in a forced-air drying oven and dried at 110°C for 12 hours. Then it was transferred to a muffle furnace and calcined at 700°C for 4 hours. After that, it was naturally cooled to room temperature to obtain the first calcined product.

[0113] 4) Add 14.34g of palladium nitrate solution to 200g of deionized water and stir well to obtain the second impregnation solution;

[0114] 5) Mix the second impregnation liquid obtained in step 4) with the first calcination product obtained in step 3), stir and impregnate at 25°C for 60 min, and then heat at 90°C for 120 min to obtain the second impregnation product.

[0115] 6) The second impregnation product was placed in a forced-air drying oven and dried at 110°C for 12 hours. Then it was transferred to a muffle furnace and calcined at 450°C for 8 hours. After that, it was naturally cooled to room temperature to obtain catalyst A3.

[0116] In catalyst A3, the Cu content is 4 wt% and the Pd content is 2 wt%, based on elemental metals.

[0117] Example 4

[0118] The procedure is carried out according to the method of Example 1, except that...

[0119] Replace the ZSM-5 molecular sieve support with an equal amount of SSZ-13 molecular sieve.

[0120] Catalyst A4 was obtained, in which the Cu content was 5 wt% and the Pd content was 1 wt%, based on elemental metals.

[0121] Example 5

[0122] The procedure is carried out according to the method of Example 1, except that...

[0123] In step 1), when preparing the first impregnation solution, 43.97g of copper nitrate trihydrate is added to 200g of deionized water;

[0124] In step 4), when preparing the second impregnation solution, 7.71g of palladium nitrate solution is added to 200g of deionized water;

[0125] Catalyst A5 was obtained, in which the Cu content was 10 wt% and the Pd content was 1 wt%, based on elemental metals.

[0126] Example 6

[0127] The procedure is carried out according to the method of Example 1, except that...

[0128] In step 1), when preparing the first impregnation solution, 11.98g of copper nitrate trihydrate is added to 200g of deionized water;

[0129] In step 4), when preparing the second impregnation solution, 7.00g of palladium nitrate solution is added to 200g of deionized water;

[0130] Catalyst A6 was obtained, in which the Cu content was 3 wt% and the Pd content was 1 wt%, based on elemental metals.

[0131] Example 7

[0132] The procedure is carried out according to the method of Example 1, except that...

[0133] In step 1), when preparing the first impregnation solution, 20.95g of copper nitrate trihydrate is added to 200g of deionized water;

[0134] In step 4), when preparing the second impregnation solution, 22.05g of palladium nitrate solution is added to 200g of deionized water;

[0135] Catalyst A7 was obtained, in which the Cu content was 5 wt% and the Pd content was 3 wt% based on elemental metals.

[0136] Example 8

[0137] The procedure is carried out according to the method of Example 1, except that...

[0138] In step 1), when preparing the first impregnation solution, 20.39g of copper nitrate trihydrate is added to 200g of deionized water;

[0139] In step 4), when preparing the second impregnation solution, 3.58g of palladium nitrate solution is added to 200g of deionized water;

[0140] Catalyst A8 was obtained, in which the Cu content was 5 wt% and the Pd content was 0.5 wt%, based on elemental metals.

[0141] Example 9

[0142] The procedure is carried out according to the method of Example 1, except that...

[0143] In step 4), when preparing the second impregnation solution, 7.19g of platinum nitrate solution (calculated as elemental platinum, with a platinum content of 15% by weight) is added to 200g of deionized water;

[0144] Catalyst A9 was obtained, in which the Cu content was 5 wt% and the Pt content was 1 wt%, based on elemental metals.

[0145] Example 10

[0146] The procedure is carried out according to the method of Example 1, except that...

[0147] In step 1), when preparing the first impregnation solution, 39.38g of ferric nitrate nonahydrate is added to 200g of deionized water;

[0148] In step 4), when preparing the second impregnation solution, 7.26g of palladium nitrate solution is added to 200g of deionized water;

[0149] Catalyst A10 was obtained, in which the Fe content was 5 wt% and the Pd content was 1 wt%, based on elemental metals.

[0150] Comparative Example 1

[0151] The procedure is carried out according to the method of Example 1, except that...

[0152] Instead of steps 1-3, replace the first calcination product in step 5) with an equal weight of ZSM-5 molecular sieve support.

[0153] Catalyst D1 was obtained, which contained no Cu and had a Pd content of 1% by weight (based on elemental metal content).

[0154] Comparative Example 2

[0155] The procedure is carried out according to the method of Example 1, except that...

[0156] In step 1), when preparing the first impregnation solution, 20.28g of copper nitrate trihydrate is added to 200g of deionized water;

[0157] Steps 4)-6) are not performed, that is, the first calcination product after the first calcination is used as catalyst D2. In catalyst D2, the Cu content is 5% by weight based on the metal element and Pd is not present.

[0158] Comparative Example 3

[0159] The procedure is carried out according to the method of Example 1, except that...

[0160] Perform steps 4) to 6) first, then perform steps 1) to 3).

[0161] That is, firstly, the second impregnation solution prepared in step 4) is used to impregnate, dry and calcine 100g of ZSM-5 molecular sieve support, and then the calcined product is used to impregnate, dry and calcine the first impregnation solution prepared in step 1).

[0162] Catalyst D3 was obtained, in which the Cu content was 5% by weight and the Pd content was 1% by weight, based on elemental metals.

[0163] Test Example 1

[0164] The powder catalysts prepared in Examples 1-10 and Comparative Examples 1-3 were subjected to tableting and granulation, and then screened to obtain catalyst particles of 60-80 mesh.

[0165] Take 200 mg of granulated catalyst (60-80 mesh) and place it in a quartz tube with an inner diameter of 5 mm. Introduce the gas to be treated, which contains 0.1 vol% monoethanolamine (MEA), 20 vol% oxygen, 5 vol% water vapor, and the balance nitrogen. The total flow rate of the gas to be treated is 1,000 mL / min, and the space velocity is 150,000 h⁻¹. -1 .

[0166] The temperature of the catalyst reaction bed was controlled by controlling the temperature of the heating furnace. The isothermal reaction activity test was carried out under normal pressure. The reaction was stabilized at each temperature point for 20 minutes. The tail gas products were detected by chromatograph and infrared gas analyzer.

[0167] The concentrations of monoethanolamine and NO in the reaction products were used to determine their relative amounts. x The conversion rate of monoethanolamine and the selectivity of N2 were calculated based on the concentration of NH3. The conversion rate of monoethanolamine was calculated as shown in Equation (1), and the N2 was calculated as shown in Equation (2).

[0168]

[0169]

[0170] The reaction temperatures and N2 selectivity at the corresponding temperatures when the monoethanolamine conversion rates are 50% (T50), 90% (T90), and 99% (T99) are shown in Table 1.

[0171] All catalysts can achieve complete oxidation of monoethanolamine at 450℃, and the N2 selectivity of each catalyst at 450℃ is shown in Table 1.

[0172] Table 1

[0173]

[0174]

[0175] As shown in Table 1, the nitrogen-containing VOCs selective catalytic oxidation catalyst prepared by the method described in this invention exhibits a T50 below 280℃, a T90 not exceeding 315℃, and a T99 not exceeding 331℃ when treating nitrogen-containing VOCs gas. Furthermore, the N2 selectivity at the temperature points corresponding to nitrogen-containing VOCs conversion rates of 50%, 90%, and 99% is all above 98%, and it can maintain an N2 selectivity of over 95% even at a high temperature of 450℃. This demonstrates not only an extremely wide temperature window but also high-temperature resistance, achieving excellent N2 selectivity while maintaining a high nitrogen-containing VOCs conversion rate. Therefore, when using the catalyst provided by this invention to treat nitrogen-containing VOCs, almost no NO is generated during the entire catalytic process. x It is very suitable for industrial applications.

[0176] The test results of Examples 1 and 4 show that when the porous support is selected as ZSM-5 molecular sieve, the resulting catalyst has significantly better catalytic activity.

[0177] Furthermore, the test results of Examples 1 and 5-8 show that when the content of the first active component in the catalyst is 4-6% by weight and / or the content of the second active component in the catalyst is 1-2% by weight, the catalytic activity and N2 selectivity of the obtained catalyst can be further improved, the overall performance of the obtained catalyst is more excellent, and it is more suitable for industrial production.

[0178] As can be seen from the test results of Examples 1 and 9-10, by selecting Cu as the first active component and / or Pd as the second active component, the resulting catalyst has significantly better catalytic activity and selectivity compared with selecting other active components.

[0179] Furthermore, the results of Example 1 and Comparative Examples 1-3 show that when the catalyst does not contain the first active metal component of the present invention, the N2 selectivity of the catalyst decreases rapidly with increasing temperature, making it unsuitable for industrial production. When the catalyst does not contain the second active metal component of the present invention, although the obtained catalyst can exhibit good N2 selectivity, the oxidation activity temperature for nitrogen-containing VOCs increases significantly. If the second active component is loaded first on the porous support of the present invention, and then the first active component is loaded, the N2 selectivity of the obtained catalyst will decrease significantly with increasing temperature, and the N2 selectivity window of the catalyst will also become significantly narrower.

[0180] In addition, the conversion rate of monoethanolamine and the N2 selectivity of the catalysts prepared in Examples 1, 4, and 5, as well as the catalysts prepared in Comparative Examples 1-3, were measured as a function of temperature. The test results are as follows: Figure 1-4 As shown.

[0181] Depend on Figure 1 , Figure 2 , Figure 3 and Figure 4 It can be seen that the catalysts prepared in Examples 1, 4 and 5 have good catalytic activity and can achieve complete oxidation of monoethanolamine before 330℃. At the same time, they can maintain a high N2 selectivity throughout the entire test temperature range, making them very suitable for industrial applications. They also have excellent catalyst performance at higher temperatures and can resist the influence of complex working conditions.

[0182] Although the catalyst prepared in Comparative Example 2 has good N2 selectivity, its conversion temperature for monoethanolamine is significantly higher and its catalytic activity is significantly worse. If this catalyst is used to treat VOCs, a large amount of heat will be required, resulting in huge energy waste, and it is clearly not suitable for large-scale industrial applications.

[0183] Although the catalysts prepared in Comparative Examples 1 and 3 also showed high activity for the conversion of monoethanolamine, their N2 selectivity decreased rapidly with increasing temperature, and the N2 selectivity window was too narrow. If changes in operating conditions occur during actual VOCs treatment, such as a sudden increase in temperature, their N2 selectivity will seriously fail to meet the requirements, and therefore they are not suitable for large-scale industrial applications.

[0184] Test Example 2

[0185] Following the method described in Test Example 1, the catalyst A1 prepared in Example 1 was subjected to a long-term activity test at 350°C. The conversion rate of monoethanolamine and the N2 selectivity were as follows: Figure 5 and Figure 6 As shown. By Figure 5 and Figure 6 It can be seen that after 75 hours of testing, the conversion rate of monoethanolamine of the catalyst remained above 99%, and the N2 selectivity remained above 99%. This shows that the nitrogen-containing VOCs selective catalytic oxidation catalyst prepared by this invention has excellent lifetime and still has excellent catalytic performance after long-term use.

[0186] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. The application of a selective catalytic oxidation catalyst for nitrogen-containing VOCs in the treatment of nitrogen-containing VOCs, wherein, The preparation method of the nitrogen-containing VOCs selective catalytic oxidation catalyst includes the following steps: 1) A solution containing the first active component is subjected to a first contact and a first calcination with a porous support in sequence to obtain a first calcination product; 2) The solution containing the second active component is subjected to a second contact and a second calcination with the first calcined product in sequence. Wherein, the first active component is Cu, and the second active component is Pt and / or Pd; The first contact results in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst having a content of 3-10% by weight, based on elemental metal. The second contact results in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst having a content of 0.5-3% by weight, based on elemental metal.

2. The application according to claim 1, wherein, The porous support is one or more of the following: ZSM-5 molecular sieve, β-type molecular sieve, SAPO-34 molecular sieve, Y-type molecular sieve, and SSZ-13 molecular sieve.

3. The application according to claim 2, wherein, The porous support is a ZSM-5 molecular sieve.

4. The application according to claim 1, wherein, The first contact results in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst having a content of 4-6% by weight, based on elemental metal.

5. The application according to claim 1, wherein, The second active component is Pd; The second contact results in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst having a content of 1-2% by weight, based on elemental metal.

6. The application according to claim 1, wherein, The conditions for the first roasting include: a temperature of 300-800℃ and a time of 2-24h.

7. The application according to claim 1, wherein, The conditions for the second roasting include: a temperature of 300-800℃ and a time of 2-24h.

8. The application according to claim 1, wherein, The preparation method further includes a drying step before the first calcination and the second calcination.

9. A method for treating nitrogen-containing VOCs in a gas, characterized in that, The method includes: contacting the gas to be treated with a nitrogen-containing VOCs selective catalytic oxidation catalyst. The preparation method of the nitrogen-containing VOCs selective catalytic oxidation catalyst includes the following steps: 1) A solution containing the first active component is subjected to a first contact and a first calcination with a porous support in sequence to obtain a first calcination product; 2) The solution containing the second active component is subjected to a second contact and a second calcination with the first calcined product in sequence. Wherein, the first active component is Cu, and the second active component is Pt and / or Pd; The first contact results in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst having a content of 3-10% by weight, based on elemental metal. The second contact results in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst having a content of 0.5-3% by weight, based on elemental metal.

10. The processing method according to claim 9, wherein, The porous support is one or more of the following: ZSM-5 molecular sieve, β-type molecular sieve, SAPO-34 molecular sieve, Y-type molecular sieve, and SSZ-13 molecular sieve.

11. The processing method according to claim 10, wherein, The porous support is a ZSM-5 molecular sieve.

12. The processing method according to claim 9, wherein, The first contact results in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst having a content of 4-6% by weight, based on elemental metal.

13. The processing method according to claim 9, wherein, The second active component is Pd; The second contact results in the prepared nitrogen-containing VOCs selective catalytic oxidation catalyst having a content of 1-2% by weight, based on elemental metal.

14. The processing method according to claim 9, wherein, The conditions for the first roasting include: a temperature of 300-800℃ and a time of 2-24h.

15. The processing method according to claim 9, wherein, The conditions for the second roasting include: a temperature of 300-800℃ and a time of 2-24h.

16. The processing method according to claim 9, wherein, The preparation method further includes a drying step before the first calcination and the second calcination.

17. The processing method according to claim 9, wherein, The contact conditions include: a contact temperature of 250-550°C and a volume hourly space velocity of 2,000-300,000 h⁻¹. -1 The flow rate of the gas to be treated is 100-5,000 mL / min.

18. The processing method according to claim 17, wherein, The contact conditions include: a contact temperature of 275-450°C and a volume hourly space velocity of 5,000-150,000 h⁻¹. -1 The flow rate of the gas to be treated is 200-3,000 mL / min.

19. The processing method according to claim 9, wherein, The nitrogen-containing VOCs are one or more of ethylenediamine, diethylamine, n-butylamine, monoethanolamine, diethanolamine, acrylonitrile, aniline, and nitrobenzene.

20. The processing method according to claim 19, wherein, The nitrogen-containing VOCs are monoethanolamines.

21. The processing method according to claim 9, wherein, The concentration of nitrogen-containing VOCs in the gas to be treated is 10-10,000 ppm.

22. The processing method according to claim 9, wherein, The contact process results in a conversion rate of over 95% for nitrogen-containing VOCs.

23. The processing method according to claim 9, wherein, The contact results in an N2 selectivity of over 95%.

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