Preparation process of efficient denitration catalyst adapting to wide environment catalysis temperature

Abstract

The invention discloses a preparation process of an efficient denitration catalyst adapting to a wide environment catalytic temperature, and relates to the technical field of denitration catalysts, the preparation process comprises the steps of S1, composite carrier precursor preparation, S2, gradient calcination treatment, S3, ion gradient loading, S4, microwave-assisted crystallization, S5, surface modification treatment, and S6, activation treatment. An active phase enriched on the surface is in contact with reaction gas preferentially, so that the oxidation-reduction response speed of a low-temperature section can be increased; the internal gradient concentration distribution forms a diffusion barrier, so that high-temperature migration and agglomeration of active components can be delayed, and the space distribution difference enables the catalyst to automatically adapt to an optimal reaction path in different temperature intervals: a surface high-activity site starts a rapid adsorption-activation process at low temperature, and an internal stable phase maintains structural rigidity at high temperature; therefore, dynamic balance is kept in a wide temperature range, thermal stress distribution is buffered through gradient design, and the risk of carrier cracking caused by severe temperature fluctuation is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of denitration catalysts, and particularly relates to a preparation process of an efficient denitration catalyst adapted to a wide environmental catalytic temperature. Background Art

[0002] With the implementation of the "Emission Standard of Air Pollutants for Thermal Power Plants GB13223 - 2011", denitration of thermal power coal has become the top priority of environmental protection in thermal power plants. By the end of 2014, the denitration transformation was basically completed nationwide. According to the requirements of the Ministry of Environmental Protection: at any operating load of thermal power plants, they must meet the emission standards. If the NOx emission concentration caused by the inoperability of the denitration system is higher than the emission limit requirement, it is recognized as exceeding the standard emission and will be punished according to law.

[0003] With the increasingly strict environmental protection regulations on the emission limits of industrial flue gas nitrogen oxides (NOx), the selective catalytic reduction (SCR) denitration technology has become the mainstream treatment method. The optimal activity temperature of traditional catalysts is concentrated at 300 - 400 °C, and it is difficult to adapt to the low temperature (<200 °C) or high temperature (>450 °C) conditions that occur during unit load fluctuations or start - stop processes, resulting in a significant decline in denitration efficiency. In view of the above problems, the following solutions are proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation process of an efficient denitration catalyst adapted to a wide environmental catalytic temperature. Through the synergistic regulation of the multi - stage dynamic impregnation process and physical and chemical parameters, the gradient distribution of active components on the surface of the carrier is realized, the temperature window of the catalytic reaction is broadened, and the problem that the optimal activity temperature of the existing catalyst is relatively concentrated and it is difficult to adapt to the low - temperature or high - temperature conditions that occur during unit load fluctuations or start - stop processes is solved.

[0005] To solve the above - mentioned technical problems, the present invention is realized through the following technical solutions:

[0006] The present invention provides an efficient denitration catalyst adapted to a wide environmental catalytic temperature. The catalyst, by mass fraction, comprises the following components: 60 - 75 parts of nano - anatase TiO2, 15 - 25 parts of modified silica sol (SiO2 content 20 wt%), 0.8 - 1.5 parts of citric acid (solid conversion), 0.3 - 0.6 parts of polyethylene glycol 6000, 0.7 - 1.4 parts of polyacrylamide (molecular weight 8 million), 4.5 - 6.2 parts of MnO2, 2.8 - 3.8 parts of CeO2, 1.2 - 1.8 parts of WO3, 0.6 - 1.1 parts of MoO3, 0.15 - 0.25 parts of 3 - aminopropyltriethoxysilane, 0.08 - 0.12 parts of lanthanum nitrate (La2O3 conversion).

[0007] The process for preparing the above - mentioned efficient denitration catalyst adapted to a wide environmental catalytic temperature comprises the following steps:

[0008] Step S1. Preparation of composite support precursor: Mix nanoscale anatase TiO₂ and modified silica sol in proportion, disperse with citric acid solution, stir with an ultrasonic and mechanical stirring coupling device, then add a pore-forming agent, and spray-dry to form a microsphere precursor;

[0009] Step S2. Gradient calcination treatment: In a programmable temperature furnace, treat the precursor in three stages under different atmospheres and temperatures to form a chemical gradient with titanium-rich on the surface and silicon-rich inside the support;

[0010] Step S3. Ion gradient loading: Use a three-stage dynamic impregnation method to prepare a composite solution containing the main active component and the promoter under different temperature, pH value and pressure conditions;

[0011] Step S4. Microwave-assisted crystallization: Place the loaded catalyst precursor in a microwave reactor, perform pulse treatment at a frequency of 2.45 GHz, and simultaneously introduce a mixed gas of air containing SO₂, with a treatment time of 30 - 60 min;

[0012] Step S5. Surface modification treatment: Immerse the catalyst in an ethanol solution containing organosilane and rare earth nitrate, ultrasonically treat for 30 min and then dry, and vacuum dry at 150 °C to form a modification layer with a thickness of 5 - 10 nm;

[0013] Step S6. Activation treatment: Perform pre-oxidation, reduction treatment and passivation treatment in a rotary roasting furnace in sequence to form a surface carbonate protection layer.

[0014] Further, in step S1, the preparation of the composite support precursor specifically includes the following steps:

[0015] Step S11: Mix nanoscale anatase TiO₂ with an average particle size between 30 - 50 nm and modified silica sol in a mass ratio of (3 - 5):1, add a 0.1 - 0.5 mol / L citric acid solution as a dispersant, and treat in an ultrasonic and mechanical stirring coupling device for 30 - 60 minutes;

[0016] Step S12: Add a pore-forming agent accounting for 0.5 - 2 wt% of the total amount, and spray-dry to form a microsphere precursor with a particle size of 80 - 120 μm.

[0017] Further, when the ultrasonic and mechanical stirring coupling device is working, the ultrasonic frequency is 40 kHz, and the stirring rate is between 800 - 1200 rpm;

[0018] The pore-forming agent is composed of polyethylene glycol 6000 and polyacrylamide in a mass ratio of 1:2;

[0019] Agglomeration of nanoparticles is eliminated through a composite dispersion process, and the two-component synergistic effect of the pore-forming agent forms interconnected hierarchical pores (micropores of 2-5 nm and mesopores of 10-30 nm).

[0020] Furthermore, in the step S2, the three stages of treating the precursor in the gradient calcination process are as follows:

[0021] The first stage: Under a nitrogen atmosphere, heat up to 300 °C at a rate of 5 °C / min and keep it for 1 h to remove physically adsorbed water;

[0022] The second stage: Switch to a mixed gas containing 5 vol% oxygen and 95 vol% nitrogen, heat up to 450 °C at a rate of 2 °C / min, and keep it for 2 h to decompose the pore-forming agent;

[0023] The third stage: Introduce a mixed gas of NH3 / Ar, heat up to 600 °C at a rate of 10 °C per minute, and after reaching 600 °C, quickly cool it to room temperature;

[0024] The NH3 in the NH3 / Ar mixed gas accounts for 3 vol%;

[0025] Segmented atmosphere control enables the carrier to form a chemical gradient with titanium-rich on the surface and silicon-rich inside. The NH3 treatment generates -NH2 functional groups on the surface to enhance the subsequent loading capacity.

[0026] Furthermore, in the step S3, the three-stage dynamic impregnation method in the ion gradient loading is specifically divided into the following three stages:

[0027] The first stage: At 30-40 °C, the pH of the impregnation solution is 3-4, vacuum-assisted impregnation for 20 min, and 50% of the total amount of the active component is loaded;

[0028] The second stage: At 50-60 °C, adjust the pH to 5-6, atmospheric pressure impregnation for 40 min, and the remaining 30% of the component is loaded;

[0029] The third stage: At 70-80 °C, adjust the pH to 7-8, high-pressure impregnation at 0.3-0.5 MPa for 30 min to complete the remaining 20% loading;

[0030] Temperature-pH-pressure synergistic regulation realizes the concentration gradient distribution of the active component from the surface to the inside of the carrier. The high-temperature and high-pressure stage promotes the active phase to enter the mesopore channels to achieve confinement stability.

[0031] Furthermore, in the step S4, when the microwave reactor performs pulse treatment in the microwave-assisted crystallization, the power is between 300 and 500 W, the pulse is in a cycle of 15 seconds, the time for continuously emitting microwaves is 10 seconds, and the time for stopping emitting microwaves is 5 seconds;

[0032] The microwave field induces the directional migration of metal ions to form a specific crystal plane orientation, and trace amounts of SO2 participate in constructing a sulfur-resistant poisoning surface structure.

[0033] Further, in step S5, the organosilane and rare earth nitrate in the surface modification treatment are 3-aminopropyltriethoxysilane and lanthanum nitrate respectively;

[0034] In step S5, the organic-inorganic composite modification layer not only protects the active sites but also provides a proton transfer channel, and the rare earth elements improve the high-temperature stability.

[0035] Further, in step S6, the specific steps of the pre-oxidation, reduction treatment and passivation treatment in the activation treatment are as follows:

[0036] Pre-oxidation: Treat in an air stream at 400 °C for 2 h;

[0037] Reduction treatment: Treat in an atmosphere containing H2 / N2 at 300 °C for 1 h;

[0038] Passivation treatment: Slowly cool to room temperature by introducing a CO2 / N2 mixed gas;

[0039] In the H2 / N2 mixed gas, H2 accounts for 5 vol%; in the CO2 / N2 mixed gas, CO2 accounts for 2 vol%;

[0040] The three-step activation method regulates the oxidation state distribution of the active phase, and CO2 passivation forms a surface carbonate protection layer to prevent pre-sintering.

[0041] The present invention has the following beneficial effects:

[0042] 1. Through the synergistic regulation of the multi-stage dynamic impregnation process and physicochemical parameters, the present invention realizes the gradient distribution of active components on the carrier surface, broadens the temperature window of the catalytic reaction. Specifically, the active phase enriched on the surface preferentially contacts the reaction gas, which can improve the redox response speed in the low-temperature section; while the gradually changing concentration distribution inside forms a diffusion barrier, effectively delaying the high-temperature migration and aggregation of active components. This spatial distribution difference enables the catalyst to automatically adapt to the optimal reaction path in different temperature ranges: at low temperatures, the highly active sites on the surface initiate a rapid adsorption-activation process, and at high temperatures, the stable phase inside maintains the structural rigidity, so as to maintain kinetic balance in a wide temperature range. The gradient design buffers the thermal stress distribution and reduces the risk of carrier cracking caused by drastic temperature fluctuations.

[0043] 2. Through the construction of a multi-scale pore network in the composite support, the present invention realizes a three-dimensional through-connected system of micropores-mesopores-macropores. The micropores provide a high specific surface area to ensure the full exposure of active sites, the mesopores serve as the main material transport channels to reduce diffusion resistance, and the macroporous structure acts as a buffer space to relieve carbon deposition blockage. This bionic hierarchical structure enables the reaction gas to form a turbulent diffusion mode inside the catalyst. Compared with traditional materials with a single pore size, it shortens the mean free path of reactants to reach the active sites. At the same time, the through-connected pores accelerate the desorption process of product molecules, avoiding the poisoning of active sites caused by excessive accumulation of intermediate products.

[0044] 3. In the present invention, the organosilane segments isolate the high-temperature sintering source through steric hindrance effects, and their amino groups construct proton-hopping conduction channels; rare earth oxides regulate the surface electron cloud density through oxygen vacancy migration and preferentially undergo coordination reactions with sulfides during sulfide invasion. This bifunctional protective layer presents an open state under low-temperature conditions to promote mass transfer, and automatically reconstructs into a dense barrier when encountering high temperatures or toxic substances. The dynamic protection mechanism can extend the anti-aging cycle of the catalyst.

[0045] 4. The three-step activation treatment of the present invention realizes the precise matching of the chemical state of the active phase and the support structure through the sequential action of oxidation-reduction-passivation. In the pre-oxidation stage, a stable strong metal-support interaction is established. The reduction treatment regulates the valence state distribution of the active components to adapt to the reaction barriers at different temperatures, and the surface modification layer formed during the passivation process fixes the optimized active configuration. This step-by-step activation strategy not only eliminates the structural stress generated during the preparation process, but also reconstructs the coordination environment of the active sites at the atomic scale, enabling the surface and interface properties of the catalyst to form a dynamic coupling with the thermodynamic requirements of the target reaction, thereby maintaining relatively excellent structural and functional relationship stability under complex working conditions.

[0046] Of course, it is not necessary for any product implementing the present invention to achieve all the above-mentioned advantages simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0048] Figure 1 It is a schematic flow chart of a preparation process for an efficient denitration catalyst adapted to a wide environmental catalytic temperature according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0049] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0050] Please refer to Figure 1 As shown, the present invention is a high-efficiency denitration catalyst suitable for a wide range of environmental catalytic temperatures. The catalyst, by mass fraction, comprises the following components: 60 - 75 parts of nano anatase TiO2, 15 - 25 parts of modified silica sol (SiO2 content 20 wt%), 0.8 - 1.5 parts of citric acid (solid conversion), 0.3 - 0.6 parts of polyethylene glycol 6000, 0.7 - 1.4 parts of polyacrylamide (molecular weight 8 million), 4.5 - 6.2 parts of MnO2, 2.8 - 3.8 parts of CeO2, 1.2 - 1.8 parts of WO3, 0.6 - 1.1 parts of MoO3, 0.15 - 0.25 parts of 3-aminopropyltriethoxysilane, 0.08 - 0.12 parts of lanthanum nitrate (La2O3 conversion).

[0051] A process for preparing a high-efficiency denitration catalyst suitable for a wide range of environmental catalytic temperatures comprises the following steps:

[0052] Step S1, preparation of a composite support precursor: Mix nano anatase TiO2 and modified silica sol in proportion, disperse with a citric acid solution, stir with an ultrasonic and mechanical stirring coupling device, then add a pore-forming agent, and spray dry to form a microsphere precursor;

[0053] Step S2, gradient calcination treatment: In a programmable temperature furnace, treat the precursor in three stages under different atmospheres and temperatures to form a chemical gradient with titanium-rich on the surface and silicon-rich inside the support;

[0054] Step S3, ion gradient loading: Use a three-stage dynamic impregnation method to prepare a composite solution containing the main active component and additives under different temperature, pH value and pressure conditions;

[0055] Step S4, microwave-assisted crystallization: Place the loaded catalyst precursor in a microwave reactor, perform pulse treatment at a frequency of 2.45 GHz, and simultaneously introduce a mixed gas of air containing SO2, with a treatment time of 30 - 60 min;

[0056] Step S5, surface modification treatment: Immerse the catalyst in an ethanol solution containing organosilane and rare earth nitrate, ultrasonically treat for 30 min and then dry, and vacuum dry at 150 °C to form a modification layer with a thickness of 5 - 10 nm;

[0057] Step S6, activation treatment: Sequentially perform pre-oxidation, reduction treatment, and passivation treatment in a rotary roasting furnace to form a surface carbonate protective layer.

[0058] Step S1, the preparation of the composite support precursor specifically includes the following steps:

[0059] Step S11: Mix nanoscale anatase TiO2 with an average particle size between 30 - 50 nm and modified silica sol at a mass ratio of (3 - 5):1, add a 0.1 - 0.5 mol / L citric acid solution as a dispersant, and treat in an ultrasonic and mechanical stirring coupling device for 30 - 60 minutes;

[0060] Step S12: Add a pore-forming agent accounting for 0.5 - 2 wt% of the total amount, and form microsphere precursors with a particle size of 80 - 120 μm by spray drying.

[0061] When the ultrasonic and mechanical stirring coupling device is working, the ultrasonic frequency is 40 kHz, and the stirring rate is between 800 - 1200 rpm;

[0062] The pore-forming agent is composed of polyethylene glycol 6000 and polyacrylamide at a mass ratio of 1:2;

[0063] Through the composite dispersion process, the agglomeration of nanoparticles is eliminated, and the two-component synergistic effect of the pore-forming agent forms through-connected hierarchical pores (micropores 2 - 5 nm, mesopores 10 - 30 nm).

[0064] Step S2, the three stages of treating the precursor in the gradient calcination treatment are as follows:

[0065] The first stage: Under a nitrogen atmosphere, heat to 300 °C at a rate of 5 °C / min and hold for 1 h to remove physically adsorbed water;

[0066] The second stage: Switch to a mixed gas containing 5 vol% oxygen and 95 vol% nitrogen, heat to 450 °C at a rate of 2 °C / min and hold for 2 h to decompose the pore-forming agent;

[0067] The third stage: Pass in an NH3 / Ar mixed gas, heat to 600 °C at a rate of 10 °C per minute, and then quickly cool to room temperature after reaching 600 °C;

[0068] NH3 in the NH3 / Ar mixed gas accounts for 3 vol%;

[0069] The segmented atmosphere control enables the support to form a chemical gradient with titanium-rich on the surface and silicon-rich inside, and the NH3 treatment generates -NH2 functional groups on the surface to enhance the subsequent loading capacity.

[0070] Step S3, the three-stage dynamic impregnation method in the ion gradient loading is specifically divided into the following three stages:

[0071] The first stage: at 30 - 40 °C, the pH of the impregnating solution is 3 - 4, vacuum-assisted impregnation for 20 min, and the total loading of the active component is 50%;

[0072] The second stage: at 50 - 60 °C, adjust the pH to 5 - 6, atmospheric pressure impregnation for 40 min, and load the remaining 30% of the component;

[0073] The third stage: at 70 - 80 °C, adjust the pH to 7 - 8, high-pressure impregnation at 0.3 - 0.5 MPa for 30 min to complete the loading of the remaining 20%;

[0074] The temperature - pH - pressure synergistic regulation realizes the concentration gradient distribution of the active component from the surface to the interior of the carrier, and the high-temperature and high-pressure stage promotes the active phase to enter the mesopores to achieve confinement stability.

[0075] Step S4, during the microwave-assisted crystallization, when the microwave reactor performs pulse treatment, the power is between 300 - 500 W, the pulse is in a cycle of 15 seconds, among which the time for continuously emitting microwaves is 10 seconds, and the time for stopping emitting microwaves is 5 seconds;

[0076] The microwave field induces the directional migration of metal ions to form a specific crystal plane orientation, and trace amounts of SO2 participate in constructing the sulfur-resistant poisoning surface structure.

[0077] Step S5, the organosilane and rare earth nitrate in the surface modification treatment are 3-aminopropyltriethoxysilane and lanthanum nitrate respectively;

[0078] In step S5, the organic-inorganic composite modification layer not only protects the active sites but also provides a proton transfer channel, and the rare earth elements improve the high-temperature stability.

[0079] Step S6, the specific steps of the pre-oxidation, reduction treatment, and passivation treatment in the activation treatment are as follows:

[0080] Pre-oxidation: treat in an air stream at 400 °C for 2 h;

[0081] Reduction treatment: treat in an atmosphere containing H2 / N2 at 300 °C for 1 h;

[0082] Passivation treatment: introduce a CO2 / N2 mixed gas and cool slowly to room temperature;

[0083] In the H2 / N2 mixed gas, H2 accounts for 5 vol%; in the CO2 / N2 mixed gas, CO2 accounts for 2 vol%; the three-step activation method regulates the oxidation state distribution of the active phase, and CO2 passivation forms a surface carbonate protective layer to prevent pre-sintering.

[0084] A specific application of this embodiment is:

[0085] I. Raw material ratio (parts by mass)

[0086] 1. Composite carrier system:

[0087] Nano anatase TiO2: 70 parts (D50 = 40 nm, specific surface area 85 m 2 / g); Modified silica sol (SiO2 content 20 wt%): 20 parts; Citric acid: 1.2 parts; Polyethylene glycol 6000: 0.5 part; Polyacrylamide (molecular weight 8 million): 1.2 parts;

[0088] 2. Active component precursor: Manganese nitrate (Mn(NO3)2·4H2O): 9.8 parts (corresponding to 5.5 parts of MnO2); Cerium nitrate (Ce(NO3)3·6H2O): 6.3 parts (corresponding to 3.2 parts of CeO2); Ammonium metatungstate ((NH4)6H2W 12 O 40 ): 2.6 parts (corresponding to 1.5 parts of WO3); Ammonium molybdate ((NH4)6Mo7O 24 ): 1.1 parts (corresponding to 0.7 part of MoO3);

[0089] 3. Surface modifier:

[0090] 3-Aminopropyltriethoxysilane: 0.2 part;

[0091] Lanthanum nitrate (La(NO3)3·6H2O): 0.15 part (corresponding to 0.1 part of La2O3);

[0092] II. Preparation process

[0093] Step 1. Composite carrier forming: Add TiO2 powder and silica sol into a solution containing 0.3 mol / L citric acid, and process in an ultrasonic-mechanical stirring system (40 kHz / 1000 rpm) for 45 minutes. After adding the pore-forming agent, spray drying (inlet temperature 180 °C, outlet temperature 90 °C) to obtain a microsphere precursor with an average particle size of 100 μm.

[0094] Step 2. Gradient calcination:

[0095] Process in a tubular furnace according to the following procedure: Heat to 300 °C at 5 °C / min under nitrogen and hold for 1 h; Switch to 5% O2 / N2, heat to 450 °C at 2 °C / min and hold for 2 h; Pass in 3% NH3 / Ar mixed gas, heat to 600 °C at 10 °C / min and then quench and cool with water;

[0096] Obtain a hierarchical pore carrier with a BET specific surface area of 152 m 2 / g (micropores 3.2 nm, mesopores 18 nm);

[0097] Step 3. Gradient impregnation:

[0098] Adopt a three-stage dynamic impregnation system: Stage 1: at 40°C, pH = 3.5, vacuum degree -0.08 MPa, impregnate for 25 min (loading 55% active component);

[0099] Stage 2: at 55°C, pH = 5.5, atmospheric pressure, impregnate for 45 min (loading 30% active component);

[0100] Stage 3: at 75°C, pH = 7.5, 0.4 MPa pressure, impregnate for 35 min (loading the remaining 15%);

[0101] XPS analysis shows that the surface Mn / Ce atomic ratio is 1.7 and the internal Mn / Ce ratio is 2.3;

[0102] Step 4, microwave crystallization: In a 2.45 GHz microwave reactor, treat for 50 minutes with a pulsed power of 400 W (10 s on / 5 s off), and simultaneously introduce a 0.2% SO2 / air mixture (flow rate 50 mL / min).

[0103] HRTEM shows that the active phase is embedded in the carrier pores in the form of 5 - 8 nm particles;

[0104] Step 5, surface modification: Immerse the catalyst in an ethanol solution containing silane and lanthanum nitrate (concentration 1.5 wt%), ultrasonically treat at 50°C for 30 min, and then vacuum dry at 150°C to form an 8 nm thick modification layer;

[0105] Step 6, activation treatment:

[0106] Carry out successively in a rotary roasting furnace:

[0107] Pre-oxidation: Treat in an air stream at 400°C for 2 h;

[0108] Reduction: Treat with 5% H2 / N2 at 300°C for 1 h;

[0109] Passivation: Slowly cool to room temperature with 2% CO2 / N2;

[0110] III. Performance testing

[0111] Denitrification performance under simulated flue gas conditions (NO 500 ppm, NH3 / NO = 1.05, O2 5%, space velocity 30000 h -1 ) is tested with reference to Table 1;

[0112] Table 1 Denitrification performance at different temperatures:

[0113] Temperature (°C) <![CDATA[NO x Conversion rate (%)]]> 150 89.7％ 250 91.3％ 350 94.1％ 450 92.5％

[0114] Sulfur resistance test: After continuous operation for 500 h in a 200 ppm SO2 atmosphere, the activity retention rate at 250°C is ≥89%.

[0115] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0116] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A highly efficient denitration catalyst that is adaptable to a wide range of environmental catalytic temperatures, characterized in that: The catalyst comprises the following components by mass: 60-75 parts of nano-rutile TiO2, 15-25 parts of modified silica sol, 0.8-1.5 parts of citric acid, 0.3-0.6 parts of polyethylene glycol 6000, 0.7-1.4 parts of polyacrylamide, 4.5-6.2 parts of MnO2, 2.8-3.8 parts of CeO2, 1.2-1.8 parts of WO3, 0.6-1.1 parts of MoO3, 0.15-0.25 parts of 3-aminopropyltriethoxysilane, and 0.08-0.12 parts of lanthanum nitrate.

2. A process for preparing a highly efficient denitration catalyst adaptable to a wide range of catalytic temperatures as claimed in claim 1, characterized in that: The following steps are involved: Step S1, preparation of composite carrier precursor: nano-scale anatase TiO2 and modified silica sol are mixed in proportion, dispersed with citric acid solution, stirred with an ultrasonic and mechanical stirring coupling device, then a pore-forming agent is added, and spray-dried to form a microsphere precursor; Step S2, gradient calcination treatment: in a programmable temperature-controlled furnace, the precursor is treated in three stages under different atmospheres and temperatures to form a chemical gradient in which the surface of the carrier is rich in titanium and the interior is rich in silicon; Step S3, ion gradient loading: using a three-stage dynamic impregnation method, a composite solution containing the main active component and the auxiliary agent is prepared under different temperature, pH value and pressure conditions; Step S4, microwave-assisted crystallization: the loaded catalyst precursor is placed in a microwave reactor and pulse treated at a frequency of 2.45 GHz, while introducing a mixture of air containing SO2 for a treatment time of 30-60 min; Step S5, surface modification treatment: immersing the catalyst in an ethanol solution containing organosilane and rare earth nitrate, ultrasonically treating for 30 minutes and then drying, and vacuum drying at 150° C. to form a modification layer with a thickness of 5-10 nm; Step S6, activation treatment: pre-oxidation, reduction treatment and passivation treatment are performed in a rotary roasting furnace in sequence to form a surface carbonate protective layer.

3. The process for preparing a highly efficient denitration catalyst that is adaptable to a wide range of catalytic temperatures according to claim 2, characterized in that: The step S1, preparation of the composite carrier precursor specifically comprises the following steps: Step S11: mixing nano-scale anatase TiO2 with an average particle size of 30-50 nm with modified silica sol in a mass ratio of (3-5):1, adding 0.1-0.5 mol / L citric acid solution as a dispersant, and treating in an ultrasonic and mechanical stirring coupling device for 30-60 minutes; Step S12: adding 0.5-2 wt% of the total amount of a pore-forming agent, and forming a microsphere precursor with a particle size of 80-120 μm through spray drying.

4. The process for preparing a highly efficient denitration catalyst that is adaptable to a wide range of catalytic temperatures according to claim 3, characterized in that: The ultrasonic and mechanical stirring coupling device has an ultrasonic frequency of 40kHz and a stirring rate between 800-1200rpm when in operation; The pore-forming agent is composed of polyethylene glycol 6000 and polyacrylamide in a mass ratio of 1:

2.

5. The process for preparing a highly efficient denitration catalyst that is adaptable to a wide range of catalytic temperatures according to claim 2, characterized in that: In step S2, the three stages of treating the precursor in the gradient calcination process are: The first stage: in a nitrogen atmosphere, the temperature was raised to 300 °C at 5 °C / min and kept at that temperature for 1 h to remove physically adsorbed water; The second stage: switch to a mixed gas containing 5 vol% oxygen and 95 vol% nitrogen, raise the temperature to 450°C at 2°C / min, and keep it for 2 hours to decompose the pore-forming agent; The third stage: introducing NH3 / Ar mixed gas, raising the temperature to 600℃ at a rate of 10℃ per minute, and then rapidly cooling to room temperature after reaching 600℃; NH3 accounts for 3 vol% of the NH3 / Ar mixed gas.

6. The process for preparing a highly efficient denitration catalyst that is adaptable to a wide range of catalytic temperatures according to claim 2, characterized in that: The three-stage dynamic impregnation method in step S3, ion gradient loading, is specifically divided into the following three stages: The first stage: at 30-40°C, the pH of the impregnation solution is 3-4, vacuum-assisted impregnation for 20 minutes, and the total amount of active components loaded is 50%; The second stage: at 50-60°C, adjust pH to 5-6, immerse at normal pressure for 40 minutes, and load the remaining 30% components; The third stage: at 70-80°C, adjust pH to 7-8, and immerse under high pressure at 0.3-0.5 MPa for 30 minutes to complete the remaining 20% ​​loading.

7. The process for preparing a highly efficient denitration catalyst that is adaptable to a wide range of catalytic temperatures according to claim 2, characterized in that: In the step S4, when the microwave reactor performs pulse treatment in the microwave-assisted crystallization, the power is between 300-500 W, the pulse has a cycle of 15 seconds, the continuous microwave emission time is 10 seconds, and the microwave emission stop time is 5 seconds.

8. The process for preparing a highly efficient denitration catalyst that is adaptable to a wide range of catalytic temperatures according to claim 2, characterized in that: In the step S5, the organic silane and the rare earth nitrate in the surface modification treatment are 3-aminopropyltriethoxysilane and lanthanum nitrate respectively.

9. The process for preparing a highly efficient denitration catalyst that is adaptable to a wide range of catalytic temperatures according to claim 2, characterized in that: In step S6, the specific steps of pre-oxidation, reduction treatment and passivation treatment in the activation treatment are respectively: Pre-oxidation: 400℃ in air flow for 2h; Reduction treatment: 300℃ in H2 / N2 atmosphere for 1h; Passivation treatment: Pass CO2 / N2 mixed gas and slowly cool to room temperature; In the H2 / N2 mixed gas, H2 accounts for 5 vol%; in the CO2 / N2 mixed gas, CO2 accounts for 2 vol%.

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