Defective catalysts, methods for their preparation and use

Abstract

The present application provides a kind of defective catalyst and its preparation method and application, the defective catalyst includes defective titanium dioxide carrier and the metal oxide active center supported on the defective titanium dioxide carrier;The metal oxide active center includes silver oxide;The defective catalyst has high specific surface area and high catalytic activity, can be used for catalytic degradation N-VOCs and synergistic production NH3, the conversion rate of N-VOCs is preferably up to 98.0% or more, while the yield of NH3 is preferably up to 100%;Realize the efficient degradation of N-VOCs and its green resource utilization of nitrogen resource.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of catalytic degradation of nitrogen-containing volatile organic compounds, and particularly relates to a defective catalyst, a preparation method and application thereof, and especially relates to a defective catalyst for catalytic degradation of nitrogen-containing volatile organic compounds and ammonia production, and a preparation method and application thereof. BACKGROUND

[0002] Nitrogen-containing volatile organic compounds (N-VOCs) are most common in organic waste gas emitted by petrochemical, pharmaceutical, steel and other industries. N-VOCs have various subtypes, mainly including fatty amine, aromatic amine, amide, alcohol amine, nitrile and nitro compounds, etc. Due to the presence of N element, their odor and toxicity are stronger than ordinary aromatic hydrocarbons and oxidative organic compounds, which can cause serious pollution and harm to the environment and human body, and therefore need to be urgently reduced and controlled, but their treatment is much more difficult than that of general volatile organic compounds (VOCs).

[0003] At present, the methods for reducing and controlling N-VOCs in industry include physical adsorption, physical condensation, combustion oxidation, catalytic oxidation and microbial degradation, etc. The combustion oxidation method is more common, but this process usually needs to be operated at high temperature, and a large amount of nitrogen oxides is generated during the reaction process. The catalytic oxidation method not only can reduce the operating temperature of the combustion oxidation method, but also can realize the resource utilization and green utilization of “N” in N-VOCs by controlling the catalyst, so the catalytic oxidation method is more popular in removing N-VOCs. However, the existing catalysts generally convert the intermediate products into N2 and / or nitrogen oxides when degrading N-VOCs, and few studies have been conducted on converting “N” in N-VOCs into NH3 which can be used as a zero-carbon energy carrier.

[0004] For example, Guo Yanglong et al. studied an Ag / Ce-Zr catalyst for catalytic combustion of nitrogen-containing volatile organic compounds, and synthesized a series of Ag / Ce-Zr solid solution catalysts with adjustable redox performance and acidity for N,N-dimethylformamide (DMF) catalytic combustion reaction by adjusting the doping amount of Zr, but the organic intermediate products were converted into N2, and the resource utilization of ammonia was not realized (see Guo et al. Ag / Ce-Zr catalysts for catalytic combustion of nitrogen-containing volatile organic compounds: balance of redox performance and acidity. Rare Metals. (2024).).

[0005] CN118059930A discloses a catalytic oxidation catalyst and a preparation method thereof and a nitrogen-containing VOCs treatment method, the catalytic oxidation catalyst containing a mixture of catalyst A and catalyst B, the catalyst A containing a first carrier and a first active component loaded on the first carrier, the catalyst B containing a second carrier and a second active component loaded on the second carrier, the first active component being one or more of Pt, Pd and Ag, the second active component being one or more of Mn, Fe, Co and Cu, and the weight ratio of the catalyst A and the catalyst B being 1:0.2-5, however, the catalyst still converts ethylenediamine mainly into N2, without realizing the conversion of N-VOCs and the resource utilization of "N".

[0006] Therefore, in view of the above defects, it is urgent to develop a catalyst and a preparation method thereof capable of efficiently degrading N-VOCs and converting "-NH2" in N-VOCs into NH3, so as to realize the emission control of N-VOCs and the resource utilization of ammonia. SUMMARY

[0007] In view of the deficiencies of the prior art, the purpose of the present application is to provide a defective catalyst for catalytic degradation of nitrogen-containing volatile organic compounds and simultaneous ammonia production, a preparation method and application thereof, in which defective titanium dioxide is used as a carrier and silver oxide is used as an active center to form a defective catalyst with high specific surface area and high catalytic activity; and the defective catalyst is used for catalytic degradation of N-VOCs and simultaneous ammonia production, realizing efficient conversion of N-VOCs and efficient production of ammonia, and the preparation process of the defective catalyst is simple, the raw materials are inexpensive and the production cost is low, and the defective catalyst is easy to industrialize.

[0008] To achieve the purpose of the present application, the following technical solutions are adopted:

[0009] In a first aspect, the present application provides a defective catalyst, which comprises a defective titanium dioxide carrier and a metal oxide active center loaded on the defective titanium dioxide carrier; and the metal oxide active center comprises silver oxide.

[0010] The defective catalyst has a defective titanium dioxide carrier with surface defects, high specific surface area, and can effectively regulate the acid sites on the surface of the obtained catalyst and the morphology of the metal active center on the surface thereof, the surface defects increase the metal anchoring sites on the surface of the carrier, thereby making the active center exist in the form of silver oxide, and present as Ag2O atomic clusters; the defective titanium dioxide carrier and the silver oxide active center synergistically act, Ag2O promotes the rupture of the C-N bond, thereby promoting the conversion of the intermediate product into NH3, the surface defects increase the number of Lewis acids on the surface of the obtained catalyst, promote the desorption of NH3, prevent further oxidation, and finally realize the emission reduction control of N-VOCs and the green resource utilization of nitrogen resources.

[0011] Preferably, the crystal form of the defective titanium dioxide carrier includes an anatase type.

[0012] The present application further preferably that the crystal form of the defective titanium dioxide carrier includes an anatase type, which has a large specific surface area and a large number of acid sites, and is more conducive to catalytic degradation of N-VOCs and the production of NH3.

[0013] Preferably, the specific surface area of the defective titanium dioxide carrier is 195.658-220.895 m 2 / g, for example, it can be 195.658 m 2 / g, 200.156 m 2 / g, 205.248 m 2 / g, 210.456 m 2 / g, 215.720 m 2 / g, 219.285 m 2 / g or 220.895 m 2 / g, etc.

[0014] Preferably, the mass ratio of the metal oxide active center to the defective titanium dioxide carrier in the defective catalyst is 1:(99-100), for example, it can be 1:99, 1:99.2, 1:99.4, 1:99.6, 1:99.8 or 1:100, etc.

[0015] The present application further preferably that the mass ratio of the metal oxide active center to the defective titanium dioxide carrier in the defective catalyst is 1:(99-100), that is, under the condition of a lower loading amount of the metal oxide active center, a higher catalytic activity can be achieved, and the production cost of the catalyst and the cost of catalytic degradation of N-VOCs are reduced.

[0016] Preferably, the specific surface area of the defective catalyst is 165.326-200.235 m 2 / g, for example, it can be 165.326 m 2 / g, 180.569 m2 / g, 185.324 m 2 / g, 190.145 m 2 / g, 195.227 m 2 / g, 198.471 m 2 / g or 200.235 m 2 / g, etc.

[0017] The present application further preferably increases the specific surface area of the defective titanium dioxide carrier by about 3 times compared to ordinary silicon dioxide, thereby increasing the specific surface area of the obtained defective catalyst and improving its adsorption capacity for N-VOCs, achieving a high conversion rate of N-VOCs.

[0018] In a second aspect, the present application provides a preparation method of the defective catalyst of the first aspect, comprising the following steps:

[0019] (1) mixing a titanium source, a silicon source and a solvent to perform hydrolysis, to obtain a titanium-silicon composite carrier;

[0020] (2) mixing the titanium-silicon composite carrier of step (1) with an alkaline solution to perform etching, to obtain the defective titanium dioxide carrier;

[0021] (3) mixing the defective titanium dioxide carrier of step (2) with a metal oxide precursor solution to perform impregnation, to obtain the defective catalyst.

[0022] The present application first uses a hydrolysis combined with alkaline etching method to prepare a defective titanium dioxide carrier, generates defects through alkaline etching, and then combines a mixed impregnation method to load metal oxide active centers on the defective titanium dioxide carrier. The defects generated by alkaline etching not only effectively regulate the existence of active centers in the form of oxides on the surface of the defective titanium dioxide carrier, but also regulate the acid sites on the surface of the obtained defective catalyst and increase the specific surface area, which is conducive to efficient catalytic degradation of N-VOCs. At the same time, it can also convert N-H2-containing intermediates into NH3, achieving efficient and green degradation of N-VOCs and effective utilization of nitrogen resources.

[0023] Preferably, the titanium source of step (1) comprises tetrabutyl titanate.

[0024] Preferably, the silicon source of step (1) comprises tetraethyl orthosilicate.

[0025] Preferably, the molar ratio of the titanium source to the silicon source in step (1) is (4.5-5.5):1, for example, it can be 4.5:1, 4.7:1, 5.0:1, 5.2:1 or 5.5:1, etc.

[0026] The molar ratio of the titanium source and the silicon source in step (1) is preferably (4.5-5.5): 1, which is beneficial to the formation of a defective titanium dioxide carrier by etching to form surface defects; if the content of the silicon source is too large, the alkali concentration will increase during etching, resulting in residual alkali in the subsequent processing and interfering with the growth of titanium dioxide crystals, thereby forming an amorphous titanium dioxide carrier; if the content of the silicon source is too small, the surface defects will be too few, and the carrier formed will be equivalent to ordinary titanium dioxide, thereby resulting in poor catalytic effect and NH3 production effect.

[0027] Preferably, the solvent comprises water and / or ethanol.

[0028] Preferably, the volume ratio of the sum of the titanium source and the silicon source to the solvent in step (1) is 1:(2.5-3.5), for example, it can be 1:2.5, 1:2.8, 1:3.0, 1:3.2 or 1:3.5, etc.

[0029] Preferably, stirring is accompanied during the hydrolysis in step (1).

[0030] Preferably, the hydrolysis time in step (1) is 10-15h, for example, it can be 10h, 11h, 12h, 13h, 14h or 15h, etc.

[0031] Preferably, after the hydrolysis in step (1), a titanium-silicon composite carrier suspension is first obtained, and then the titanium-silicon composite carrier suspension is sequentially subjected to first rotary evaporation and first calcination to obtain the titanium-silicon composite carrier.

[0032] Preferably, the temperature of the first rotary evaporation is 50-70℃, for example, it can be 50℃, 55℃, 60℃, 65℃ or 70℃, etc.

[0033] Preferably, the rotation speed of the first rotary evaporation is 50-80r / min, for example, it can be 50r / min, 55r / min, 60r / min, 65r / min, 70r / min, 75r / min or 80r / min, etc.

[0034] Preferably, the heating rate of the first calcination is 8-12℃ / min, for example, it can be 8℃ / min, 9℃ / min, 10℃ / min, 11℃ / min or 12℃ / min, etc.

[0035] Preferably, the final temperature of the first calcination is 450-650℃, for example, it can be 450℃, 500℃, 550℃, 600℃ or 650℃, etc.

[0036] Preferably, the holding time of the first calcination is 3-6h, for example, it can be 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h, etc.

[0037] Preferably, after the first rotary evaporation of the titanium-silicon composite carrier suspension, the first drying is performed first, and then the first calcination is performed.

[0038] Preferably, the temperature of the first drying is 80-100℃, for example, it can be 80℃, 85℃, 90℃, 95℃ or 100℃, etc.

[0039] Preferably, the time of the first drying is 4-12h, for example, it can be 4h, 6h, 8h, 10h or 12h, etc.

[0040] Preferably, the alkaline solution in step (2) comprises any one or a combination of at least two of sodium hydroxide solution, ammonia water or potassium hydroxide solution, wherein a typical but non-limiting combination includes a combination of sodium hydroxide solution and ammonia water, a combination of ammonia water and potassium hydroxide solution, or a combination of sodium hydroxide solution and potassium hydroxide solution, etc.

[0041] Preferably, the concentration of the alkaline solution in step (2) is 1.8-2.2mol / L, for example, it can be 1.8mol / L, 2.0mol / L or 2.2mol / L, etc.

[0042] Preferably, the solid-liquid ratio of the titanium-silicon composite carrier to the alkaline solution in step (2) is 1:(10-20)g / mL, for example, it can be 1:10g / mL, 1:12g / mL, 1:14g / mL, 1:16g / mL, 1:18g / mL or 1:20g / mL, etc.

[0043] The present application further preferably has the solid-liquid ratio of the titanium-silicon composite carrier to the alkaline solution in step (2) is 1:(10-20)g / mL, which is beneficial to fully etching the titanium-silicon composite carrier to produce more defects, thereby increasing the surface area of the defective titanium dioxide carrier, and further improving the catalytic activity of the obtained defective catalyst and fully regulating the subsequent active centers to exist in the form of oxides; if the solid-liquid ratio of the titanium-silicon composite carrier to the alkaline solution is too large, i.e. the alkaline solution is too little, the alkaline etching will not be sufficient, thereby resulting in a decrease in the defects of the defective titanium dioxide carrier and a decrease in the active centers on its surface in the form of oxides, leading to a decrease in the catalytic activity of the obtained defective catalyst, and finally leading to a decrease in the N-VOCs conversion rate and the NH3 yield; if the solid-liquid ratio of the titanium-silicon composite carrier to the alkaline solution is too small, i.e. the alkaline solution is too much, the N-VOCs conversion rate and the NH3 yield are not significantly improved, but instead, it causes reagent waste and increases the cost.

[0044] Preferably, the etching in step (2) is performed at a temperature of 40-80℃, such as 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃, preferably 40-60℃.

[0045] Preferably, the etching in step (2) is performed at a temperature of 40-60℃, which is beneficial to the formation of the defective titania support, thus to the successful preparation of the defective catalyst and the improvement of the N-VOCs conversion rate and NH3 yield; if the etching temperature is too low, the etching is insufficient, the surface defects of the defective titania support are reduced, the active centers in the form of oxides are reduced, and the subsequent N-VOCs conversion rate and NH3 yield are reduced; if the etching temperature is too high, the N-VOCs conversion and NH3 production effect are not obviously improved, but the energy consumption is increased.

[0046] Preferably, the etching in step (2) is performed with stirring.

[0047] Preferably, the etching in step (2) is performed for 10-15h, such as 10h, 11h, 12h, 13h, 14h or 15h.

[0048] Preferably, the etching is followed by obtaining a defective titania support suspension, and then the defective titania support suspension is sequentially subjected to centrifugal washing and second drying to obtain the defective titania support.

[0049] Preferably, the washing liquid for the centrifugal washing comprises water and / or ethanol.

[0050] Preferably, the end point of the centrifugal washing is that the pH of the supernatant is 7.0-7.5, such as 7.0, 7.2, 7.3, 7.4 or 7.5.

[0051] The centrifugal washing in the present application is to remove the alkaline solution remaining on the surface.

[0052] Preferably, the second drying is performed at a temperature of 80-100℃, such as 80℃, 85℃, 90℃, 95℃ or 100℃.

[0053] Preferably, the second drying is performed for 4-12h, such as 4h, 6h, 8h, 10h or 12h.

[0054] Preferably, the mixing and impregnation in step (3) is performed at a temperature of 40-80℃, such as 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃.

[0055] Preferably, the mixing and impregnating in step (3) is performed for 1-3 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, or the like.

[0056] Preferably, the mixing and impregnating in step (3) is performed with stirring.

[0057] Preferably, the metal oxide precursor solution in step (3) comprises an AgNO3 solution.

[0058] Preferably, the mass ratio of the metal oxide precursor in the metal oxide precursor solution in step (3) to the defective titanium dioxide carrier is 1: (99-100), for example, 1:99, 1:99.2, 1:99.4, 1:99.6, 1:99.8, 1:100, or the like.

[0059] The application further preferably has the mass ratio of the metal oxide precursor in the metal oxide precursor solution in step (3) to the defective titanium dioxide carrier is 1: (99-100), that is, under the condition of a lower metal oxide loading amount, a higher N-VOCs conversion rate and NH3 yield can be obtained, and the cost is lower.

[0060] Preferably, after the mixing and impregnating, a mixed impregnation solution is obtained, and then the mixed impregnation solution is sequentially subjected to second rotary evaporation and second calcination to obtain the defective catalyst.

[0061] Preferably, the temperature of the second rotary evaporation is 40-80℃, for example, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, or the like.

[0062] Preferably, the rotation speed of the second rotary evaporation is 50-80 r / min, for example, 50 r / min, 55 r / min, 60 r / min, 65 r / min, 70 r / min, 75 r / min, 80 r / min, or the like.

[0063] Preferably, the time of the second rotary evaporation is 0.5-1 hour, for example, 0.5 hour, 0.6 hour, 0.7 hour, 0.8 hour, 1 hour, or the like.

[0064] Preferably, the heating rate of the second calcination is 8-12℃ / min, for example, 8℃ / min, 9℃ / min, 10℃ / min, 11℃ / min, 12℃ / min, or the like.

[0065] Preferably, the final temperature of the second calcination is 250-350℃, for example, 250℃, 280℃, 300℃, 320℃, 350℃, or the like.

[0066] Preferably, the second baking has a holding time of 3-6h, for example, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h, etc.

[0067] Preferably, after the second rotary evaporation of the mixed impregnation solution, the third drying and second baking are sequentially performed to obtain the defective catalyst.

[0068] Preferably, the third drying has a temperature of 90-120℃, for example, 90℃, 100℃, 110℃ or 120℃, etc.

[0069] Preferably, the third drying has a time of 8-12h, for example, 8h, 9h, 10h, 11h or 12h, etc.

[0070] As a further preferred technical solution of the present application, the process flow shown in the figure is performed, and the preparation method of the defective catalyst comprises the following steps: Figure 1

[0071] (1) The titanium source and the silicon source with a molar ratio of (4.5-5.5):1 are mixed with a solvent for hydrolysis to obtain a titanium-silicon composite carrier suspension; then the titanium-silicon composite carrier suspension is subjected to first rotary evaporation under the condition of 50-70℃ and 50-80r / min, and then is subjected to first baking by increasing the temperature to 450-650℃ at a temperature increasing rate of 8-12℃ / min and holding for 3-6h to obtain the titanium-silicon composite carrier.

[0072] The volume ratio of the sum of the titanium source and the silicon source to the first solvent is 1:(2.5-3.5);

[0073] (2) The titanium-silicon composite carrier in step (1) is mixed with an alkaline solution with a concentration of 1.8-2.2mol / L according to a solid-liquid ratio of 1:(10-20)g / mL, and is etched under the condition of 40-80℃ and stirring for 10-15h, and then is subjected to centrifugal washing and drying in sequence to obtain the defective titanium dioxide carrier.

[0074] (3) The defective titanium dioxide carrier in step (2) is mixed with a metal oxide precursor solution at 40-80℃ for impregnation for 1-3h to obtain a mixed impregnation solution; then is subjected to second rotary evaporation under the condition of 40-80℃ and 50-80r / min; and then is subjected to second baking by increasing the temperature to 250-350℃ at a temperature increasing rate of 8-12℃ / min and holding for 3-6h to obtain the defective catalyst.

[0075] The mass ratio of the metal oxide precursor in the metal oxide precursor solution to the defective titanium dioxide carrier is 1:(99-100).

[0076] ​In a third aspect, the present application provides a method for catalytic degradation of nitrogen-containing volatile organic compounds (N-VOCs) and ammonia production, which uses the defective catalyst of the first aspect; the method comprises the following steps: nitrogen-containing volatile organic compounds are degraded and ammonia is produced under the action of the defective catalyst.

[0077] The defective catalyst of the first aspect is used to catalytically degrade the nitrogen-containing volatile organic compounds and produce ammonia, which realizes efficient conversion of N-VOCs, and efficiently converts intermediate products containing -NH2 into NH3, avoids pollution of N-VOCs, and realizes green resource utilization of nitrogen resources. The method is simple, and the temperature required to achieve the highest conversion rate of N-VOCs and the highest yield of NH3 is low, the amount of catalyst required is less, that is, the energy consumption and cost of the reaction are low.

[0078] Preferably, the nitrogen-containing volatile organic compounds include any one or a combination of ethanolamine, N,N-dimethylethanolamine or N,N-dimethylamide, wherein a typical but non-limiting combination includes a combination of ethanolamine and N,N-dimethylethanolamine, a combination of N,N-dimethylethanolamine and N,N-dimethylamide, or a combination of ethanolamine and N,N-dimethylamide, etc.

[0079] Preferably, the gas hourly space velocity of the catalytic reaction is 50000-70000h -1 , for example, it can be 50000h -1 , 60000h -1 or 70000h -1 .

[0080] Preferably, the temperature of the catalytic reaction is 80-300℃, for example, it can be 80℃, 100℃, 120℃, 150℃, 180℃, 200℃, 220℃, 250℃, 280℃ or 300℃, etc., preferably 220-280℃.

[0081] The numerical range of the present application includes not only the point values listed above, but also any point values between the above numerical ranges that are not listed, and the present application does not list the specific point values included in the range for the sake of brevity and simplicity.

[0082] Compared with the prior art, the present application has the following beneficial effects:

[0083] (1) The defect catalyst provided by the present application takes defective titanium dioxide as a carrier and silver oxide as an active center, and the two synergistically work together to make the defect catalyst have high specific surface area and high catalytic activity, realize efficient degradation of N-VOCs, and also convert the intermediate product containing-NH2 generated in the process of degrading N-VOCs into NH3, realize emission reduction control of N-VOCs and green resource utilization of nitrogen resources, and the defect catalyst is low in price, non-toxic, easy to separate and recycle, and has wide application prospect.

[0084] (2) The preparation method of the defect catalyst provided by the present application first successfully prepares a defective titanium dioxide carrier by adopting a combination of a hydrolysis method and alkali etching, and then loads a metal oxide active center on the defective titanium dioxide carrier by adopting a mixed impregnation method, successfully prepares the defect catalyst which shows high catalytic activity in the catalytic degradation of N-VOCs and can convert the intermediate product into NH3, and further optimizes parameters such as solid-liquid ratio and etching temperature in the preparation process to further improve the conversion rate of catalytic degradation of N-VOCs and the NH3 production efficiency; the preparation method has wide raw material sources, simple and controllable preparation process, and is easy to industrialize.

[0085] (3) The method for catalytic degradation of nitrogen-containing volatile organic compounds and simultaneous ammonia production provided by the present application adopts the defect catalyst as described above, and obtains high N-VOCs conversion rate and NH3 yield, preferably up to 98.0% or more for the N-VOCs conversion rate, and preferably up to 100% for the NH3 yield; the temperature required to reach the highest N-VOCs conversion rate is preferably as low as 230℃ or lower; the temperature required to reach the highest NH3 yield is as low as 280℃; the amount of the defect catalyst required by the method is relatively small, and the defect catalyst is non-toxic and harmless, and friendly to the environment. BRIEF DESCRIPTION OF DRAWINGS

[0086] Figure 1 is a process flow chart of the preparation method of the defect catalyst provided by the present application;

[0087] Figure 2 is a synchrotron R space fitting diagram of the defect catalyst Ag2O / TiO2-D provided by Example 1 of the present application;

[0088] Figure 3 is a synchrotron R space fitting diagram of a silver oxide standard sample. DETAILED DESCRIPTION

[0089] The technical solutions of the present application will be further described below by combining the drawings and through specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application, and should not be regarded as specific limitations on the present application.

[0090] The experimental methods in the following examples and comparative examples, application examples and comparative application examples are all conventional methods unless otherwise specified; the experimental materials used are all purchased from conventional biochemical reagent manufacturers unless otherwise specified.

[0091] I. Examples

[0092] Example 1

[0093] The present example provides a preparation method of a defective catalyst, comprising the following steps:

[0094] (1) mixing and stirring titanium tetrabutoxide and tetraethyl orthosilicate in a molar ratio of 5:1 with 300 mL of water to perform hydrolysis, to obtain a titanium-silicon composite carrier suspension; then performing first rotary evaporation on the titanium-silicon composite carrier suspension under the condition of 60℃ and 60 r / min, and then heating to 500℃ at a heating rate of 10℃ / min and maintaining for 4 h to perform first calcination, to obtain the titanium-silicon composite carrier;

[0095] The volume ratio of the sum of titanium tetrabutoxide and tetraethyl orthosilicate to water is 1:3;

[0096] (2) mixing 16 g of the titanium-silicon composite carrier in step (1) with 300 mL of a sodium hydroxide solution with a concentration of 2 mol / L according to a solid-liquid ratio of 1:18.75 g / mL, etching under the condition of 50℃ and stirring for 12 h, and then washing by water centrifugation and drying at 100℃ for 4 h, to obtain the defective titanium dioxide carrier;

[0097] (3) mixing and impregnating the defective titanium dioxide carrier in step (2) with an AgNO3 solution under the condition of 50℃ and stirring for 2 h to obtain a mixed impregnation solution; then performing second rotary evaporation under the condition of 60℃ and 60 r / min; and then heating to 300℃ at a heating rate of 10℃ / min and maintaining for 4 h to perform second calcination, to obtain the defective catalyst; the mass ratio of the defective titanium dioxide carrier to AgNO3 in the AgNO3 solution is 1:99.5.

[0098] The defective catalyst obtained in the present example comprises silver oxide active centers with a mass ratio of 1:99.5 supported on a defective titanium dioxide carrier and the defective titanium dioxide carrier; the crystal form of the defective titanium dioxide carrier is anatase type, the specific surface area of the defective titanium dioxide carrier is 203.255 m 2 / g, and the specific surface area of the defective catalyst is 179.561 m 2 / g.

[0099] From Figure 2 and Figure 3It can be seen that, compared with the R space fitting results of the catalyst Ag2O / TiO2-D obtained in the embodiment and the Ag2O standard sample, it can be seen that the characteristic peak positions of Ag-O and Ag-O-Ag bonds in the defective catalyst are consistent with those of the Ag2O standard sample; thus it can be confirmed that the active center of the defective catalyst obtained in the embodiment exists in the form of Ag2O.

[0100] Example 2

[0101] The embodiment provides a preparation method of a defective catalyst, and the preparation method comprises the following steps:

[0102] (1) titanium tetrabutoxide and tetraethyl orthosilicate with a molar ratio of 4.5:1 are mixed with 300 mL of water and stirred for hydrolysis to obtain a titanium-silicon composite carrier suspension; the titanium-silicon composite carrier suspension is subjected to first rotary evaporation under the condition of 50 ℃ and 80 r / min, and then is subjected to first calcination by increasing the temperature to 650 ℃ at a temperature increasing rate of 8 ℃ / min and maintaining for 3 h to obtain the titanium-silicon composite carrier;

[0103] The volume ratio of the sum of the titanium tetrabutoxide and the tetraethyl orthosilicate to the water is 1:2.5;

[0104] (2) 30 g of the titanium-silicon composite carrier in step (1) is mixed with 300 mL of a sodium hydroxide solution with a concentration of 1.8 mol / L at a solid-liquid ratio of 1:10 g / mL, etching is performed at 40 ℃ under stirring for 15 h, and then water centrifugal washing and drying at 80 ℃ for 12 h are performed to obtain the defective titanium dioxide carrier;

[0105] (3) the defective titanium dioxide carrier in step (2) is mixed with an AgNO3 solution under stirring at 40 ℃ for 3 h to obtain a mixed impregnation solution; second rotary evaporation is performed under the condition of 40 ℃ and 50 r / min; and then second calcination is performed by increasing the temperature to 250 ℃ at a temperature increasing rate of 12 ℃ / min and maintaining for 6 h to obtain the defective catalyst; the mass ratio of the defective titanium dioxide carrier to AgNO3 in the AgNO3 solution is 1:99.

[0106] The defective catalyst obtained in the embodiment comprises silver oxide active centers with a mass ratio of 1:99 supported on a defective titanium dioxide carrier and the defective titanium dioxide carrier; the crystal form of the defective titanium dioxide carrier is anatase, the specific surface area of the defective titanium dioxide carrier is 195.658 m 2 / g, and the specific surface area of the defective catalyst is 165.326 m 2 / g.

[0107] Example 3

[0108] The embodiment provides a preparation method of a defective catalyst, and the preparation method comprises the following steps:

[0109] (1) titanium tetrabutoxide and tetraethyl orthosilicate with a molar ratio of 5.5:1 are mixed with 300 mL of water and stirred to hydrolyze, so as to obtain a titanium-silicon composite carrier suspension; the titanium-silicon composite carrier suspension is subjected to first rotary evaporation under the condition of 70 DEG C and 50 r / min, then is heated to 450 DEG C at a heating rate of 12 DEG C / min and kept for 6 h to perform first calcination, so as to obtain the titanium-silicon composite carrier;

[0110] The volume ratio of the sum of the titanium tetrabutoxide and the tetraethyl orthosilicate to the water is 1:3.5;

[0111] (2) 15 g of the titanium-silicon composite carrier in step (1) is mixed with 300 mL of a sodium hydroxide solution with a concentration of 2.2 mol / L at a solid-liquid ratio of 1:20 g / mL, etching is performed under the condition of 60 DEG C and stirring for 10 h, then washing by centrifugation with water and drying at 100 DEG C for 4 h are performed, so as to obtain the defective titanium dioxide carrier;

[0112] (3) the defective titanium dioxide carrier in step (2) and an AgNO3 solution are mixed and impregnated under the condition of 80 DEG C and stirring for 1 h, so as to obtain a mixed impregnation solution; second rotary evaporation is performed under the condition of 80 DEG C and 80 r / min; then second calcination is performed by heating to 350 DEG C at a heating rate of 10 DEG C / min and keeping for 3 h, so as to obtain the defective catalyst; the mass ratio of the defective titanium dioxide carrier to AgNO3 in the AgNO3 solution is 1:100.

[0113] The defective catalyst obtained in the embodiment comprises silver oxide active centers with a mass ratio of 1:100 supported on a defective titanium dioxide carrier and the defective titanium dioxide carrier; the crystal form of the defective titanium dioxide carrier is anatase type, the specific surface area of the defective titanium dioxide carrier is 201.326 m 2 / g, and the specific surface area of the defective catalyst is 199.650 m 2 / g.

[0114] Embodiment 4

[0115] The embodiment provides a preparation method of a defective catalyst, and the preparation method is the same as that in Embodiment 1, except that the molar ratio of the titanium tetrabutoxide to the tetraethyl orthosilicate in step (1) is 4.2:1.

[0116] Embodiment 5

[0117] The embodiment provides a preparation method of a defective catalyst, and the preparation method is the same as that in Embodiment 1, except that the molar ratio of the titanium tetrabutoxide to the tetraethyl orthosilicate in step (1) is 5.8:1.

[0118] Example 6

[0119] The present example provides a method for preparing a defective catalyst, which is identical to that of Example 1 except that the solid-liquid ratio of the titanium-silicon composite carrier to the sodium hydroxide solution is 1:9.5 g / mL.

[0120] Example 7

[0121] The present example provides a method for preparing a defective catalyst, which is identical to that of Example 1 except that the solid-liquid ratio of the titanium-silicon composite carrier to the sodium hydroxide solution is 1:21 g / mL.

[0122] Example 8

[0123] The present example provides a method for preparing a defective catalyst, which is identical to that of Example 1 except that the etching temperature in step (2) is 35°C.

[0124] Example 9

[0125] The present example provides a method for preparing a defective catalyst, which is identical to that of Example 1 except that the etching temperature in step (2) is 80°C.

[0126] Example 10

[0127] The present example provides a method for preparing a defective catalyst, which is identical to that of Example 1 except that the mass ratio of AgNO3 to the defective titanium dioxide carrier in the AgNO3 solution in step (3) is 1.5:99.

[0128] Example 11

[0129] Example 11

[0130] The present example provides a method for preparing a defective catalyst, which is identical to that of Example 1 except that the AgNO3 solution in step (3) is replaced by Cu(NO3)2.

[0131] Example 11

[0132] The present example provides a method for preparing a defective catalyst, which is identical to that of Example 1 except that steps (1) and (2) are not performed, and titanium dioxide is directly mixed with AgNO3 solution for impregnation.

[0133] In the present example, since ordinary titanium dioxide is used, after being mixed with AgNO3 solution for impregnation, the active center exists in the form of Ag nanoparticles.

[0134] Example 11

[0135] This comparative example provides a method for preparing a catalyst, which is the same as in Example 1 except that only steps (1) and (2) are performed, and step (3) is not performed.

[0136] III. Application Examples

[0137] The following application examples and comparative application examples were conducted using a Fourier transform infrared detector coupled with a gas chromatograph-mass spectrometer, with a gas volume hourly space velocity (VHSV) of 50,000–70,000 h⁻¹. -1 The temperature for the catalytic reaction is 80–300℃.

[0138] Application Example 1

[0139] This application example provides a method for the catalytic degradation of ethanolamine to co-produce ammonia, the method comprising the following steps: introducing an oxygen content of 20% (N2 as the carrier gas) and a volume hourly space velocity of 60,000 h⁻¹. -1 Under the conditions, ethanolamine with a concentration of 200 ppm was degraded by catalytic reaction and produced NH3 under the action of the defective catalyst provided in Example 1.

[0140] Application Example 2

[0141] This application example provides a method for the catalytic degradation of ethanolamine to co-produce ammonia, the method comprising the following steps: introducing an oxygen content of 15% (N2 as the carrier gas) and a volume hourly space velocity of 50,000 h⁻¹. -1 Under the conditions, ethanolamine at a concentration of 180 ppm and the defective catalyst provided in Example 2 were used for catalytic degradation to produce NH3.

[0142] Application Example 3

[0143] This application example provides a method for the catalytic degradation of ethanolamine to co-produce ammonia, the method comprising the following steps: introducing an oxygen content of 25% (N2 as the carrier gas) and a volume hourly space velocity of 70,000 h⁻¹. -1 Under these conditions, ethanolamine at a concentration of 220 ppm and the defective catalyst provided in Example 3 were catalytically degraded to produce NH3.

[0144] Application Examples 4-10

[0145] Keeping all other conditions the same as in Application Example 1, only the defective catalyst used was changed. Specifically, Application Examples 4 to 10 used the defective catalysts prepared in Examples 4 to 10, respectively.

[0146] IV. Comparative Application Examples

[0147] Comparative Application Examples 1-3

[0148] The other conditions are kept the same as in Application Example 1, only the catalyst used is changed, specifically, Comparative Application Examples 1-3 use the catalysts prepared in Comparative Examples 1-3, respectively.

[0149] Comparative Application Example 4

[0150] This comparative example provides a method for catalytic degradation of ethanolamine with ammonia production, which is the same as Application Example 1 except that TiO2 is used as the catalyst.

[0151] Comparative Application Example 5

[0152] This comparative example provides a method for catalytic degradation of ethanolamine, which is the same as Application Example 1 except that no catalyst is used and only oxygen with a content of 20% (N2 as carrier gas) is introduced.

[0153] Comparative Application Example 6

[0154] This comparative example provides a method for catalytic degradation of ethanolamine, which is the same as Application Example 1 except that no catalyst is used and only 50 ppm CO2 (N2 as carrier gas) is introduced.

[0155] Comparative Application Example 7

[0156] This comparative example provides a method for catalytic degradation of ethanolamine, which is the same as Application Example 1 except that no catalyst is used and only 200 ppm CO2 (N2 as carrier gas) is introduced.

[0157] Comparative Application Example 8

[0158] This comparative example provides a method for catalytic degradation of ethanolamine, which is the same as Application Example 1 except that no catalyst is used and only 400 ppm CO2 (N2 as carrier gas) is introduced.

[0159] V. Test and Results

[0160] The highest conversion rate of ethanolamine and the required catalytic temperature, the conversion rate of ethanolamine at 220°C and the yield of NH3 at 220°C in the methods for catalytic degradation of ethanolamine with ammonia production provided by the above application examples and comparative application examples are tested and calculated, and the results are shown in Table 1.

[0161] Table 1

[0162]

[0163]

[0164] Wherein " / " means no NH3 production.

[0165] From the data in Table 1, it can be seen that:

[0166] (1) From the comprehensive application examples 1-3, it can be seen that the defect catalyst prepared by using defective titanium dioxide as the carrier and silver oxide as the active center can be used for catalytic degradation of N-VOCs to produce NH3, and a high ethanolamine conversion rate and NH3 yield are obtained, the ethanolamine conversion rate is as high as 98.0% or more and the NH3 yield is as high as 52.8% or more at 220°C; and the temperature required to reach the highest conversion rate is as low as 230°C or less, and the temperature required to reach the highest NH3 yield is as low as 280°C.

[0167] (2) From the comprehensive application examples 1 and 4-5, it can be seen that, compared with application example 1, the molar ratio of tetrabutyl titanate to tetraethyl silicate in application example 4 is smaller, resulting in a decrease in the ethanolamine conversion rate to 87.6% and the NH3 yield to 35.6% at 220°C, and an increase in the temperature required to reach the highest ethanolamine and the highest NH3 yield; and the molar ratio of tetrabutyl titanate to tetraethyl silicate in application example 5 is larger, resulting in a decrease in the ethanolamine conversion rate to 90.6% and the NH3 yield to 50.3% at 220°C, and an increase in the temperature required to reach the highest ethanolamine and the highest NH3 yield; thus, it can be seen that the application further preferably selects the molar ratio of the titanium source to the silicon source in the preparation process of the defect catalyst to be (4.5-5.5):1, which further improves the catalytic activity of the obtained defect catalyst, thereby improving the conversion of N-VOCs and the effect of producing NH3.

[0168] (3) From the comprehensive application examples 1 and 6-9, it can be seen that, compared with application example 1, the solid-liquid ratio of the titanium-silicon composite carrier to the sodium hydroxide solution in application example 6 is larger, resulting in a decrease in the ethanolamine conversion rate to 95.6% and the NH3 yield to 51.0% at 220°C, and an increase in the temperature required to reach the highest ethanolamine and the highest NH3 yield; and the solid-liquid ratio of the titanium-silicon composite carrier to the sodium hydroxide solution in application example 7 is smaller, which does not significantly improve the effect of catalytic degradation of ethanolamine and production of NH3, and will cause waste of reagents; the etching temperature in application example 8 is lower, resulting in a decrease in the ethanolamine conversion rate to 73.2% and the NH3 yield to 27.5% at 220°C, and an increase in the temperature required to reach the highest ethanolamine and the highest NH3 yield; and when the etching temperature in application example 9 is higher, the effect is not significantly improved, but causes a large energy consumption; thus, it can be seen that the application further preferably selects the solid-liquid ratio of the alkali etching in the preparation process of the defect catalyst to be 1:(10-20) g / mL and the temperature to be 40-60°C, which further improves the effect of catalytic degradation of N-VOCs to produce NH3.

[0169] (4) From the comprehensive application examples 1 and 10-11, it can be seen that, compared with the application example 1, the loading amount of AgNO3 in the AgNO3 solution in the application example 10 is higher, and the catalytic degradation and NH3 production effect are not significantly improved, so it can be seen that the defect catalyst in the application can achieve higher conversion rate of N-VOCs and NH3 yield under lower loading amount of metal oxide active center.

[0170] (5) From the comprehensive application examples 1 and comparative application examples 1-4, it can be seen that, in the comparative application example 1, Cu(NO3)2 solution is used, the active center is CuO, although ethanolamine can be degraded, but NH3 cannot be produced; in the comparative application example 2, the carrier titanium dioxide has no defect, resulting in smaller specific surface area, and limited surface acid site regulation effect, and the active center exists in the form of silver nanoparticles, resulting in lower conversion rate of ethanolamine and lower NH3 at the same temperature compared with the application example 1; the required temperature is higher under the same conversion rate and NH3 yield; in the comparative application example 3, since the silver oxide active center is not loaded, the catalytic effect and NH3 production effect are poor; in the comparative application example 4, ordinary titanium dioxide is used, no defect is generated, and no silver oxide active center is generated, resulting in poor catalytic effect and NH3 production effect.

[0171] (6) From the comprehensive application examples 1 and comparative application examples 5-8, it can be seen that, in the comparative application examples 5-8, N-VOCs cannot be completely degraded under the condition of not using any catalyst and only under pure oxygen or different concentrations of CO2, the conversion rate of ethanolamine is as low as 42.0% or less at 300℃, and even almost no degradation, and the intermediate product cannot be converted into NH3, and the efficient degradation of N-VOCs and the synergistic NH3 production effect cannot be achieved.

[0172] The applicant declares that the technical solutions of the application are illustrated by the above specific embodiments, but the application is not limited thereto, that is, it does not mean that the application must rely on the above embodiments to be implemented. It should be understood by those skilled in the art that any improvement of the application, equivalent replacement of each raw material of the product of the application, addition of auxiliary ingredients, selection of specific mode, etc. all fall within the protection scope and disclosure scope of the application.

[0173] The preferred embodiments of the application are described in detail above, but the application is not limited to the specific details in the above embodiments, and various simple modifications can be made to the technical solutions of the application within the technical concept of the application, and these simple modifications all belong to the protection scope of the application.

[0174] It should be further noted that various specific technical features described in the above specific embodiments can be combined in any suitable manner, and in order to avoid unnecessary repetition, the present application will not describe various possible combinations again.

Claims

1. A method for catalytic degradation of nitrogen-containing volatile organic compounds with ammonia production, characterized in that, The method comprises the following steps: nitrogen-containing volatile organic matters are degraded by catalytic reaction under the action of a defective catalyst and ammonia is generated. The defective catalyst comprises a defective titanium dioxide carrier and a metal oxide active center loaded on the defective titanium dioxide carrier; the metal oxide active center comprises silver oxide. The mass ratio of the metal oxide active center to the defective titanium dioxide carrier in the defective catalyst is 1:(99-100). The preparation method of the defective titanium dioxide carrier comprises the following steps: (1) mixing a titanium source, a silicon source and a solvent to perform hydrolysis and then first calcination to obtain a titanium-silicon composite carrier; (2) mixing the titanium-silicon composite carrier in step (1) with an alkaline solution to perform etching to obtain the defective titanium dioxide carrier.

2. The method of claim 1, wherein, The crystal form of the defective titanium dioxide carrier comprises an anatase type.

3. The method of claim 1, wherein, The specific surface area of the defective titanium dioxide support is 195.658 ~ 220.895 m 2 / g.

4. The method of claim 1, wherein, The specific surface area of the defective catalyst is 165.326~200.235 m 2 / g.

5. The method of claim 1, wherein, The preparation method of the defective catalyst comprises the following steps: (1) mixing a titanium source, a silicon source and a solvent to perform hydrolysis and then first calcination to obtain a titanium-silicon composite carrier; (2) mixing the titanium-silicon composite carrier in step (1) with an alkaline solution to perform etching to obtain the defective titanium dioxide carrier; (3) mixing and impregnating the defective titanium dioxide carrier in step (2) with a metal oxide precursor solution and then second calcination to obtain the defective catalyst.

6. The method of claim 1, wherein, The titanium source in step (1) comprises tetrabutyl titanate.

7. The method of claim 1, wherein, The silicon source in step (1) comprises tetraethyl orthosilicate.

8. The method of claim 1, wherein, The molar ratio of the titanium source to the silicon source in step (1) is (4.5-5.5):

1.

9. The method of claim 1, wherein, The volume ratio of the sum of the titanium source and the silicon source to the solvent in step (1) is 1:(2.5-3.5).

10. The method of claim 1, wherein, In step (1), the titanium-silicon composite carrier suspension is first obtained after hydrolysis, and then the titanium-silicon composite carrier suspension is sequentially subjected to first rotary evaporation and first calcination to obtain the titanium-silicon composite carrier.

11. The method of claim 10, wherein, The temperature of the first rotary evaporation is 50-70°C.

12. The method of claim 10, wherein, The rotation speed of the first rotary evaporation is 50-80 r / min.

13. The method of claim 1, wherein, The heating rate of the first calcination is 8-12°C / min.

14. The method of claim 1, wherein, The final temperature of the first calcination is 450-650°C.

15. The method of claim 1, wherein, The holding time of the first calcination is 3-6 h.

16. The method of claim 1, wherein, The alkaline solution in step (2) comprises any one or a combination of at least two of a sodium hydroxide solution, ammonia water or a potassium hydroxide solution.

17. The method of claim 1, wherein, The concentration of the alkaline solution in step (2) is 1.8-2.2 mol / L.

18. The method of claim 1, wherein, The solid-liquid ratio of the titanium-silicon composite carrier to the alkaline solution in step (2) is 1:(10-20) g / mL.

19. The method of claim 1, wherein, The temperature of the etching in step (2) is 40-80°C.

20. The method of claim 19, wherein, The temperature of the etching in step (2) is 40-60°C.

21. The method of claim 1, wherein, The etching in step (2) is accompanied by stirring.

22. The method of claim 1, wherein, The etching time in step (2) is 10-15 h.

23. The method of claim 5, wherein, The temperature of the mixing and impregnation in step (3) is 40-80°C.

24. The method of claim 5, wherein, The mixing and impregnation time in step (3) is 1-3 h.

25. The method of claim 5, wherein, The metal oxide precursor solution in step (3) comprises an AgNO3 solution.

26. The method of claim 5, wherein, The mass ratio of the metal oxide precursor in the metal oxide precursor solution in step (3) to the defective titanium dioxide carrier is 1:(99-100).

27. The method of claim 5, wherein, The mixed impregnation is followed by obtaining a mixed impregnation solution, and then sequentially performing second rotary evaporation and second calcination on the mixed impregnation solution to obtain the defective catalyst.

28. The method of claim 27, wherein, The temperature of the second rotary evaporation is 40-80℃.

29. The method of claim 27, wherein, The rotation speed of the second rotary evaporation is 50-80r / min.

30. The method of claim 5, wherein, The heating rate of the second calcination is 8-12℃ / min.

31. The method of claim 5, wherein, The final temperature of the second calcination is 250-350℃.

32. The method of claim 5, wherein, The holding time of the second calcination is 3-6h.

33. The method of claim 1, wherein, The preparation method of the defective catalyst comprises the following steps: (1) mixing a titanium source and a silicon source with a molar ratio of (4.5-5.5):1 and a solvent to perform hydrolysis, to obtain a titanium-silicon composite carrier suspension; then performing first rotary evaporation on the titanium-silicon composite carrier suspension at 50-70℃ and 50-80r / min, and then performing first calcination by increasing the temperature to 450-650℃ at a heating rate of 8-12℃ / min and holding for 3-6h, to obtain the titanium-silicon composite carrier; The volume ratio of the sum of the titanium source and the silicon source to the solvent is 1:(2.5-3.5); (2) mixing the titanium-silicon composite carrier in step (1) with an alkaline solution with a concentration of 1.8-2.2mol / L according to a solid-liquid ratio of 1:(10-20)g / mL, etching at 40-80℃ under stirring for 10-15h, to obtain the defective titanium dioxide carrier; (3) mixing the defective titanium dioxide carrier in step (2) and a metal oxide precursor solution at 40-80℃ to perform mixed impregnation for 1-3h, to obtain a mixed impregnation solution; Then performing second rotary evaporation at 40-80℃ and 50-80r / min, and then performing second calcination by increasing the temperature to 250-350℃ at a heating rate of 8-12℃ / min and holding for 3-6h, to obtain the defective catalyst; The mass ratio of the metal oxide precursor in the metal oxide precursor solution to the defective titanium dioxide carrier is 1:(99-100).

34. The method of claim 1, wherein, The nitrogen-containing volatile organic compound includes any one or a combination of at least two of ethanolamine, N,N-dimethylethanolamine or N,N-dimethylformamide.

35. The method of claim 1, wherein, The temperature of the catalytic reaction is 80-300℃.

36. The method of claim 35, wherein, The temperature of the catalytic reaction is 220-280℃.

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