Denitration catalyst, preparation method thereof and internal denitration system of catalytic cracking device

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a denitration catalyst, a preparation method thereof and an internal denitration system of a catalytic cracking device. The denitration catalyst comprises a composite carrier, an active component and a modified component, the composite carrier comprises TiO2 and ZrO2; the active components comprise V2O5 and WO3; and the modified component comprises MoO3. The denitration catalyst disclosed by the invention can be directly filled in a catalytic cracking (FCC) device, and is suitable for the working condition that the temperature fluctuates severely at 300-600 DEG C. The FCC cracking furnace flue is directly filled with the catalyst, selective catalytic reduction can be achieved on a high-temperature flue gas passing path, external heat exchange cooling and additional SCR devices are omitted, the system design is simplified, and energy consumption and occupied space are reduced. The catalyst provided by the invention has efficient denitration performance and excellent thermal stability, is especially suitable for denitration in an FCC device, and has a wide industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a denitrification catalyst and its preparation method, and an internal denitrification system for a catalytic cracking unit. Background Technology

[0002] Fluid catalytic cracking (FCC) is a core method for improving the yield of light oil products and optimizing product structure in petroleum refining, and it has been widely used in various refining units worldwide. The FCC process cracks heavy oil into light oil products such as gasoline and diesel at high temperatures, and has advantages such as mature processes and strong economics, thus occupying an important position in refining enterprises. However, FCC units often use external fuel combustion for heating during operation, which often results in large amounts of nitrogen oxides (NOx). x These NOs are produced. x The main sources are thermal and rapid NO during fuel combustion. x The formation of NO involves reactions such as the pyrolysis and oxidation of nitrogen-containing components in some feedstock oils. Because the combustion temperature in FCC units is typically high (350~450 ℃) and the combustion process fluctuates significantly (up to 500~550 ℃), NO... x Emission concentrations are unstable.

[0003] Currently, regarding the nitrogen oxides (NOx) emitted during the operation of catalytic cracking (FCC) units... x The main treatment method for NO is an external exhaust gas treatment device, with the most common technology being Selective Catalytic Reduction (SCR). This technology involves injecting a reducing agent (such as ammonia or urea) into the exhaust gas, which, under the action of a V2O5-WO3 / TiO2 catalyst, reduces NO. x Nitrogen oxides are reduced to harmless N2 and H2O, thus achieving safe emissions. SCR technology, with its advantages of high reduction efficiency and few byproducts, has been widely used. However, the catalyst (V2O5-WO3 / TiO2) used in SCR devices is best suited for an operating temperature range of 300–400 °C. When the flue gas temperature fluctuates drastically and rises to 500–550 °C, this catalyst cannot effectively remove nitrogen oxides. Furthermore, frequent high temperatures can lead to thermal aging and deactivation of the catalyst, resulting in poor thermal stability. Therefore, developing denitrification catalytic materials that can operate stably under these conditions has become an urgent need for technological upgrades in this field. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a denitrification catalyst and its preparation method, as well as an internal denitrification system for a catalytic cracking unit. The denitrification catalyst provided by this invention exhibits good thermal stability, maintaining ≥80% NO content within a temperature range of 300~575℃. x The conversion rate, after thermal aging, can still maintain ≥80% NO within a temperature range of 300~550℃. x Conversion rate; applicable to variable temperature conditions inside catalytic cracking units.

[0005] This invention provides a denitrification catalyst, comprising a composite support, an active component, and a modified component; The composite support comprises TiO2 and ZrO2; The active components include V2O5 and WO3; The modified component includes MoO3.

[0006] Preferably, the mass ratio of TiO2 to ZrO2 is 1:0.2~0.5.

[0007] Preferably, the mass ratio of the composite carrier to V2O5 is 1:0.005~0.007; and the mass ratio of the composite carrier to WO3 is 1:0.07~0.09.

[0008] Preferably, the mass ratio of the composite carrier to MoO3 is 1:0.004~0.028.

[0009] This invention also provides a method for preparing the denitrification catalyst described in the above technical solution, comprising the following steps: After impregnating TiO2 in a Zr salt solution, the composite support was obtained by first drying and first calcination. The composite support is impregnated in a mixed salt solution for the second time, and then subjected to a second drying and a second calcination to obtain a denitrification catalyst; the solutes in the mixed salt solution include vanadate, tungstate and molybdate.

[0010] Preferably, the Zr salt in the Zr salt solution is zirconium nitrate; the mass ratio of TiO2 to zirconium nitrate is 2:1.2~1.6.

[0011] Preferably, the first calcination temperature is 550~600℃, and the holding time is 3~6h.

[0012] Preferably, the vanadate is ammonium metavanadate, and the mass ratio of the composite support to ammonium metavanadate is 2:0.01~0.02; the tungstate is ammonium tungstate, and the mass ratio of the composite support to ammonium tungstate is 2:0.18~0.2; the molybdate is ammonium molybdate, and the mass ratio of the composite support to ammonium molybdate is 2:0.01~0.06.

[0013] Preferably, the second calcination temperature is 550~600℃, and the holding time is 3~6h.

[0014] The present invention also provides an internal denitrification system for a catalytic cracking unit, including a catalytic cracking reactor, wherein the upper part of the catalytic cracking reactor is provided with a catalytic cracking feedstock inlet and the lower part is provided with a catalytic cracking product outlet, the inlet and outlet being connected by a catalytic cracking pipeline; the catalytic cracking reactor is also provided with a heating flue gas inlet and a flue gas outlet for heating the catalytic cracking pipeline; A denitrification unit is installed in the path through which the heating flue gas passes inside the catalytic cracking reactor; The denitrification unit includes an ammonia injection pipe and a bed of denitrification catalyst arranged sequentially in the direction of the heated flue gas passage; the denitrification catalyst is the denitrification catalyst described in the above technical solution or the denitrification catalyst obtained by the above preparation method.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a denitrification catalyst, comprising a composite support, an active component, and a modifying component; the composite support comprises TiO2 and ZrO2; the active component comprises V2O5 and WO3; and the modifying component comprises MoO3. The denitrification catalyst of this invention uses TiO2 and ZrO2 as the composite support, with ZrO2 forming a Ti-Zr solid solution structure. This structure maintains crystal stability in operating environments below 600℃, reducing the loss of specific surface area of ​​the support under high-temperature conditions. Based on this, the active component V2O5 on the Ti-Zr composite support surface can maintain uniform dispersion on the support, inhibiting the migration of V2O5 on the support during thermal aging and effectively controlling the formation of polymerized V2O5 (the polymerized state of V2O5 easily leads to excessive redox capacity of the catalyst, causing ammonia itself to be oxidized by V2O5, thus failing to effectively react with NO). x (The reaction proceeds). Furthermore, the addition of MoO3 helps improve the thermal stability of the Ti-Zr support, maintain a high specific surface area, and also reduces V2O5 aggregation; WO3, as an auxiliary agent, provides adsorption sites for NH3. The catalyst of this invention exhibits excellent NO removal at high temperatures. x Its conversion performance (denitrification performance) can effectively reduce nitrogen oxide emissions in FCC units, and it can maintain high catalytic activity even at high temperature.

[0016] Test data show that the denitrification catalyst of this invention has excellent high-temperature stability: it can maintain ≥80% NO within a temperature range of 300~575℃. x The conversion rate, after thermal aging, can still maintain ≥80% NO within a temperature range of 300~550℃. xEven under aging conditions at 600℃, the conversion rate can still maintain high catalytic activity and stability, and it has strong anti-sintering ability, making it suitable for complex working conditions in FCC cracking furnaces.

[0017] Currently, in the after-treatment of tail gas denitrification in catalytic cracking (FCC) processes, the SCR system is generally located downstream of the regeneration flue gas or cracker flue gas emission channel. External heat exchangers or steam cooling systems are used to cool the flue gas to a temperature range suitable for catalytic reactions (typically 300-400 °C). This means the SCR denitrification system is located outside the FCC unit, resulting in a complex tail gas system structure, high energy consumption, large footprint, and high construction costs, which is detrimental to the compactness and integration of the unit. This invention provides an internal denitrification system for catalytic cracking units. The denitrification catalyst of this invention can be directly loaded inside the FCC cracker to remove nitrogen oxides from the flue gas inside the FCC unit, reducing reliance on external denitrification equipment, simplifying system design and installation, and improving the reliability and economy of the denitrification system. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the layout of an FCC device internally filled with an SCR catalyst in this invention. Figure 2 This is a schematic diagram of the apparatus for thermal aging of the catalyst and for evaluating the denitrification performance of the catalyst in this invention. Figure 3 The results show the denitrification conversion rates of the SCR catalysts in Example 1 and Comparative Examples 1-2 under temperature fluctuations. Figure 4 The results of the denitrification conversion rate of the SCR catalyst after thermal aging in Application Example 1 and Comparative Application Examples 1-2 under temperature fluctuations; Figure 5 VWTi-Zr modified with different Mo ratios for NO x Performance comparison chart for restoration; Figure 6 VWTi-Zr modified with different Mo ratios for heat aging on NO x Performance comparison chart for restoration. Detailed Implementation

[0020] This invention provides a denitrification catalyst, comprising a composite support, an active component, and a modified component; The composite support comprises TiO2 and ZrO2; The active components include V2O5 and WO3; The modified component includes MoO3.

[0021] In this invention, the preferred mass ratio of TiO2 to ZrO2 is 1:0.2~0.5, specifically 1:0.25 or 1:0.3. The ZrO2 loading described in this invention effectively enhances the thermal stability and sintering resistance of the composite carrier.

[0022] In this invention, the mass ratio of the composite carrier to V2O5 is preferably 1:0.005~0.007, specifically 1:0.006; the mass ratio of the composite carrier to WO3 is preferably 1:0.07~0.09, specifically 1:0.08.

[0023] In this invention, the mass ratio of the composite carrier to MoO3 is preferably 1:0.004~0.028, specifically 1:0.005, 1:0.006, 1:0.007, 1:0.010, 1:0.012, 1:0.020 or 1:0.024.

[0024] The denitrification catalyst of this invention maintains ≥80% NO within a temperature range of 300~575℃. x The conversion rate of the denitrification catalyst, after thermal aging at 600℃ for 168 hours, can still maintain ≥80% NO conversion within a temperature range of 300~550℃. x Conversion rate; applicable to variable temperature conditions inside catalytic cracking units.

[0025] This invention also provides a method for preparing the denitrification catalyst described in the above technical solution, comprising the following steps: After impregnating TiO2 in a Zr salt solution, the composite support was obtained by first drying and first calcination. The composite support is impregnated in a mixed salt solution for the second time, and then subjected to a second drying and a second calcination to obtain a denitrification catalyst; the solutes in the mixed salt solution include vanadate, tungstate and molybdate.

[0026] Unless otherwise specified, all materials and equipment used in this invention are commercially available products in the field.

[0027] In this invention, TiO2 is first impregnated in a Zr salt solution, and then subjected to a first drying and a first calcination to obtain a composite carrier.

[0028] In this invention, the TiO2 is preferably TiO2 powder, and the particle size of the TiO2 powder is preferably 10~100nm, specifically 50nm.

[0029] In this invention, the Zr salt in the Zr salt solution is preferably zirconium nitrate (Zr(NO3)4); the mass ratio of TiO2 to zirconium nitrate is preferably 2:1.2~1.6, specifically 2:1.44. The concentration of Zr salt in the Zr salt solution is preferably 0.02~0.04 g / mL, specifically 0.0288 g / mL; the mass ratio of TiO2 to the volume of the Zr salt solution is preferably 2 g:40~60 mL, specifically 2 g:50 mL.

[0030] In this invention, the first impregnation is preferably carried out under stirring, and the stirring time is preferably 6 to 10 hours, specifically 8 hours; the stirring time of this invention allows the Zr salt to be fully loaded on the TiO2 surface.

[0031] In this invention, the first drying specifically involves drying the suspension after the first impregnation as a whole to obtain a solid powder; the temperature of the first drying is preferably 100~103℃, and the time is preferably 4~8h, specifically 6h.

[0032] In this invention, the preferred temperature for the first calcination is 550-600°C, and the preferred holding time is 3-6 hours. The first calcination is preferably carried out in an air atmosphere. During the first calcination process, the metal salt is calcined to form a metal oxide.

[0033] After obtaining the composite support, the present invention further impregnates the composite support in a mixed salt solution for a second time, and then performs a second drying and a second calcination to obtain a denitrification catalyst; the solutes in the mixed salt solution include vanadate, tungstate and molybdate.

[0034] In this invention, the vanadate is preferably ammonium metavanadate, and the mass ratio of the composite support to ammonium metavanadate is preferably 2:0.01~0.02, specifically 2:0.0154; the tungstate is preferably ammonium tungstate, and the mass ratio of the composite support to ammonium tungstate is preferably 2:0.18~0.2, specifically 2:0.192; the molybdate is preferably ammonium molybdate, and the mass ratio of the composite support to ammonium molybdate is preferably 2:0.01~0.06, specifically 2:0.0141, 2:0.0282, or 2:0.0568. The mass ratios described above enable the obtained denitrification catalyst Mo-VWTi-Zr to exhibit high NO content at higher temperatures (400~500℃). x Removal efficiency (NO) x The conversion rate is greater than 95%; simultaneously, the prepared catalyst, after undergoing thermal aging (600℃, 168h), can still maintain more than 90% NO content at 400~550℃. x Conversion efficiency.

[0035] In this invention, the second drying specifically involves drying the entire suspension after the second impregnation to obtain a solid powder; the temperature of the second drying is preferably 100~103℃, and the time is preferably 4~8h, specifically 6h.

[0036] In this invention, the preferred temperature for the second calcination is 550-600°C, and the preferred holding time is 3-6 hours. The second calcination is preferably carried out in an air atmosphere. During the second calcination process, the metal salt is calcined to form a metal oxide.

[0037] The present invention also provides an internal denitrification system for a catalytic cracking unit, including a catalytic cracking reactor, wherein the upper part of the catalytic cracking reactor is provided with a catalytic cracking feedstock inlet and the lower part is provided with a catalytic cracking product outlet, the inlet and outlet being connected by a catalytic cracking pipeline; the catalytic cracking reactor is also provided with a heating flue gas inlet and a flue gas outlet for heating the catalytic cracking pipeline; A denitrification unit is installed in the path through which the heating flue gas passes inside the catalytic cracking reactor; The denitrification unit includes an ammonia injection pipe and a bed of denitrification catalyst arranged sequentially in the direction of the heated flue gas passage; the denitrification catalyst is the denitrification catalyst described in the above technical solution or the denitrification catalyst obtained by the above preparation method.

[0038] The path of the heated flue gas is the path from the heated flue gas inlet to the exhaust outlet.

[0039] Figure 1 This is a schematic diagram of the layout of the FCC device internally filled with SCR catalyst in this invention. Heated flue gas from an external boiler enters from the bottom of the reactor, while the pyrolysis feedstock enters from the top of the reactor via a pipe. Pyrolysis occurs in the presence of an external heat source (heated flue gas), and the products flow out from the bottom. The heated flue gas, entering from the bottom, mixes thoroughly with NH3 injected from the ammonia injection pipe before contacting the denitrification catalyst. It then contacts the denitrification catalyst at a high temperature (300~600℃) to complete the reduction of nitrogen oxides.

[0040] The denitrification catalyst of this invention is suitable for variable temperature conditions inside catalytic cracking units. This invention achieves NO removal directly within the pyrolysis furnace by coupling the SCR catalyst inside the furnace. x This invention reduces operating and investment costs by reducing the reduction of nitrogen oxides (NOx). In traditional cracking processes, the reactor requires an external heat source, and the NOx generated during heating needs to be treated by an SCR unit at the tail end of the pyrolysis furnace. This invention directly loads the catalyst inside the FCC furnace chamber (inside the FCC heating unit), directly treating the NOx generated during heating. After the NOx passes through the SCR catalyst bed and is reduced to N2, it can be directly released into the atmosphere. This invention directly treats NOx within the FCC unit. xThis process reduces the construction and investment required for SCR units.

[0041] To further illustrate the present invention, the denitrification catalyst and its preparation method, as well as the internal denitrification system of the catalytic cracking unit provided by the present invention, are described in detail below with reference to the accompanying drawings and embodiments. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0042] Example 1 Take 2g of TiO2 powder (particle size approximately 50 nm) and immerse it in 50mL of an aqueous solution containing 1.44g of zirconium nitrate. Stir for 8 hours to ensure uniform distribution of zirconium nitrate on the TiO2 surface. The impregnated mixture (suspension) is dried at 100℃ for 6 hours and then calcined at 600℃ for 3 hours to obtain the Ti-Zr composite support.

[0043] Two g of Ti-Zr composite support was placed in a 50 mL mixed salt solution containing ammonium metavanadate, ammonium tungstate, and ammonium molybdate. The solution was stirred for 8 hours to ensure uniform mixing of the substances. The amounts of ammonium metavanadate, ammonium tungstate, and ammonium molybdate in the mixed salt solution were 15.4 mg, 192 mg, and 14.1 mg, respectively. After impregnation, the mixture was dried at 100 °C for 6 hours, and the solid powder was calcined at 600 °C for 3 hours to obtain a fresh Mo-VWTi-Zr catalyst.

[0044] Comparative Example 1 The preparation method of the Ti-Zr composite support is the same as that in Example 1.

[0045] 2 g of Ti-Zr composite support was placed in a mixed salt solution (50 mL) containing ammonium metavanadate and ammonium tungstate, and stirred for 8 h to ensure uniform mixing. The amount of ammonium metavanadate added to the mixed salt solution was 15.4 mg, and the amount of ammonium tungstate added was 192 mg. After impregnation, the mixture was dried at 100 °C for 6 h, and the solid powder was calcined at 600 °C for 3 h to obtain fresh VWTi-Zr catalyst.

[0046] Comparative Example 2 2 g of TiO2 powder support was placed in a mixed salt solution (50 mL) containing ammonium metavanadate and ammonium tungstate, and stirred for 8 h to ensure uniform mixing. The amount of ammonium metavanadate added to the mixed salt solution was 15.4 mg, and the amount of ammonium tungstate added was 192 mg. After impregnation, the powder was dried at 100 °C for 6 h, and then calcined at 600 °C for 3 h to obtain fresh VWTi catalyst.

[0047] Application Example 1 The Mo-VWTi-Zr catalyst from Example 1 was placed in... Figure 2The device was subjected to thermal aging treatment to obtain the thermally aged Mo-VWTi-Zr catalyst.

[0048] The thermal aging temperature was 600 ℃, and the thermal aging time was 168 h. The gases used for thermal aging were as follows: nitrogen oxide concentration of 500 ppm, ammonia concentration of 500 ppm, oxygen volume concentration of 5%, and the remaining gas was nitrogen, with a total flow rate of 300 mL / min.

[0049] Comparative Application Example 1 The VWTi-Zr catalyst in Comparative Example 1 was subjected to thermal aging treatment using the same method as in Application Example 1 to obtain the thermally aged VWTi-Zr catalyst.

[0050] Comparative Application Example 2 The VWTi catalyst in Comparative Example 2 was subjected to thermal aging treatment using the same method as in Application Example 1 to obtain the thermally aged VWTi catalyst.

[0051] Test Example 1 Catalytic reaction performance determination: 0.3g of catalyst was placed in... Figure 2 In the reaction apparatus, the total gas flow rate required for the experimental process is 300 mL / min, of which the concentration of nitrogen oxides is 500 ppm, the concentration of ammonia is 500 ppm, the volume concentration of oxygen is 5%, and the remaining gas is nitrogen.

[0052] The nitrogen oxides produced after the reaction were measured using an infrared gas analyzer (KM940 MKII, KANE, England). x The pollutant removal efficiency is calculated using the following formula: NO x Conversion rate = (1 - [NO]) x ] out / [NO x ] in ) × 100%; In the formula, [NO x ] in This represents the sum of nitric oxide (NO) and nitrogen dioxide (NO2) that enter, [NO x ] out It represents the sum of nitric oxide (NO) and nitrogen dioxide (NO2) emitted.

[0053] 1. The Mo-VWTi-Zr catalyst from Example 1, the VWTi-Zr catalyst from Comparative Example 1, and the VWTi catalyst from Comparative Example 2 were placed in... Figure 2In the apparatus, the temperature variation conditions inside the FCC unit were simulated by changing the furnace temperature, and the NOx reduction efficiency was measured within the temperature range of 300–600 °C. The conversion efficiency of nitrogen oxides was measured at reaction temperatures of 300 °C, 350 °C, 400 °C, 450 °C, 500 °C, 550 °C, 575 °C, and 600 °C. The results are as follows: Figure 3 As shown, Depend on Figure 3 It can be seen that, in the fresh state, all three catalysts exhibit extremely high NO levels in the temperature range of 300℃ to 450℃. x In terms of conversion performance, the Mo-VWTi-Zr catalyst achieved a conversion efficiency of nearly 100%, slightly better than the VWTi-Zr and VWTi catalysts. When the temperature was further increased to 500℃, the Mo-VWTi-Zr catalyst still maintained a conversion rate of approximately 98%, while VWTi-Zr and VWTi remained stable at 96% and 97%, respectively. When the temperature climbed to 550℃, Mo-VWTi-Zr still maintained a high activity of around 95%, while VWTi-Zr and VWTi decreased to approximately 90% and 80%, respectively. Until 600℃, the conversion rates of all three decreased significantly, with Mo-VWTi-Zr reaching approximately 70%, significantly better than VWTi-Zr (≈55%) and VWTi (40%), indicating that the synergistic effect of Mo modification and the Ti-Zr composite support provides a wider efficient temperature window.

[0054] 2. The thermally aged Mo-VWTi-Zr catalyst from Application Example 1, the thermally aged VWTi-Zr catalyst from Comparative Application Example 1, and the thermally aged VWTi catalyst from Comparative Application Example 2 were placed in... Figure 2 In the apparatus, the temperature variation conditions inside the FCC unit were simulated by changing the furnace temperature, and the NOx reduction efficiency was measured within the temperature range of 300–600 °C. The conversion efficiency of nitrogen oxides was measured at reaction temperatures of 300 °C, 350 °C, 400 °C, 450 °C, 500 °C, 550 °C, 575 °C, and 600 °C. The results are as follows: Figure 4 As shown.

[0055] Depend on Figure 4It can be seen that after thermal aging at 600℃ for 168 hours, the overall activity of all three catalysts decreased. However, Mo-VWTi-Zr still maintained a high denitrification efficiency of ≥80% within the temperature range of 300℃ to 550℃, which is significantly better than the conversion rates of aged VWTi-Zr (≈78%, 550℃) and VWTi (≈70%, 550℃) in the same temperature range. At 500℃, Mo-VWTi-Zr also maintained a conversion efficiency of about 93%, while VWTi-Zr and VWTi decreased to 90% and 91%, respectively. As the temperature rose to 600℃, Mo-VWTi-Zr still achieved a conversion rate of about 60%, while VWTi-Zr and VWTi further decreased to about 45% and 33%, respectively.

[0056] The above results show that the Mo-VWTi-Zr catalyst not only has excellent fresh denitrification activity, but also exhibits outstanding thermal aging stability.

[0057] Examples 2-3 The preparation method of the Ti-Zr composite support is the same as that in Example 1.

[0058] 2 g of Ti-Zr composite support was placed in a mixed salt solution (50 mL) containing ammonium metavanadate, ammonium tungstate, and ammonium molybdate. The mixture was stirred for 8 hours to ensure uniform mixing. The amount of ammonium metavanadate added to the mixed salt solution was 15.4 mg, and the amount of ammonium tungstate was 192 mg. Catalysts with different MoO3 contents were prepared by varying the amount of ammonium molybdate added: 14.1 mg (Example 1), 28.2 mg, and 56.8 mg. After impregnation, the catalyst was dried at 100 °C for 6 hours, and the solid powder was calcined at 600 °C for 3 hours to obtain fresh Mo-VWTi-Zr catalyst (Example 1), 1-Mo-VWTi-Zr catalyst (Example 2), and 2-Mo-VWTi-Zr catalyst (Example 3), respectively.

[0059] Figure 5 A comparison of the NOx reduction performance of fresh VWTi-Zr modified with different Mo ratios; Figure 6 The graph shows a comparison of the NOx reduction performance of VWTi-Zr modified with different Mo ratios under heat aging. The heat aging method is the same as in Application Example 1; the test method is the same as in Test Example 1.

[0060] Depend on Figure 5 It can be seen that catalysts modified with different amounts in the fresh state all improved the NOx conversion efficiency at high temperatures. Among them, the Mo-VWTi-Zr and 2-Mo-VWTi-Zr catalysts showed more significant improvements in NOx conversion efficiency at high temperatures. Specifically, the Mo-VWTi-Zr catalyst showed improved NOx conversion efficiency at 550℃, 575℃, and 600℃.x The conversion efficiencies were 96%, 86%, and 70%, respectively; the 2-Mo-VWTi-Zr catalyst showed good conversion efficiency for NO at 550℃, 575℃, and 600℃. x The conversion efficiencies were 96%, 81%, and 68%, respectively. Meanwhile, the 1-Mo-VWTi-Zr catalyst showed good performance at high temperatures for NO... x The improvement in reduction efficiency for NO was not significant at 550℃, 575℃, and 600℃. x The conversion efficiencies were 87%, 76%, and 67%, respectively. In contrast, the unmodified VWTi-Zr catalyst showed better conversion efficiency for NO at 550℃, 575℃, and 600℃. x The conversion efficiencies were 86%, 75%, and 56%, respectively.

[0061] Depend on Figure 6 It can be seen that the overall activity of all three catalysts decreased after thermal aging at 600℃ for 168 hours. However, the Mo-VWTi-Zr and 1-Mo-VWTi-Zr catalysts still exhibited good activity at high temperatures for NO removal even after aging. x The reduction was carried out, and the Mo-VWTi-Zr catalyst performed better, specifically: the Mo-VWTi-Zr catalyst showed better reduction of NO at 550℃, 575℃ and 600℃. x The conversion efficiencies were 88%, 74%, and 61%, respectively; the 1-Mo-VWTi-Zr catalyst showed good conversion efficiency for NO at 550℃, 575℃, and 600℃. x The conversion efficiencies were 82%, 66%, and 52%, respectively. In contrast, the unmodified VWTi-Zr catalyst showed better conversion efficiency for NO at 550℃, 575℃, and 600℃. x The conversion efficiencies were 79%, 66%, and 45%, respectively. The 2-Mo-VWTi-Zr catalyst, after thermal aging, exhibited lower high-temperature activity than the VWTi-Zr catalyst after thermal aging, with NOx conversion efficiencies of 68%, 57%, and 39% at 550℃, 575℃, and 600℃, respectively.

[0062] In this invention, the support is strengthened by composited with ZrO2 on the TiO2 surface during the support preparation process, thus preparing a Ti-Zr composite material. Subsequently, using the Ti-Zr composite material as the support and V2O5 and WO3 as active components, a Mo-VWTi-Zr catalyst is prepared through MoO3 modification. The denitrification catalyst prepared by this invention can adapt to the variable temperature environment inside an FCC and can efficiently treat NO. x The reduction process is carried out, and the denitrification catalyst has good geothermal stability, which can mitigate the thermal aging and deactivation problems caused by the high temperature inside the FCC.

[0063] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, not all embodiments. People can obtain other embodiments based on the present invention without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A denitrification catalyst, characterized in that, Includes composite carriers, active components, and modified components; The composite support comprises TiO2 and ZrO2; The active components include V2O5 and WO3; The modified component includes MoO3.

2. The denitrification catalyst according to claim 1, characterized in that, The mass ratio of TiO2 to ZrO2 is 1:0.2~0.

5.

3. The denitrification catalyst according to claim 1 or 2, characterized in that, The mass ratio of the composite carrier to V2O5 is 1:0.005~0.007; the mass ratio of the composite carrier to WO3 is 1:0.07~0.

09.

4. The denitrification catalyst according to claim 1 or 2, characterized in that, The mass ratio of the composite carrier to MoO3 is 1:0.004~0.

028.

5. The method for preparing the denitrification catalyst according to any one of claims 1 to 4, characterized in that, Includes the following steps: After impregnating TiO2 in a Zr salt solution, the composite support was obtained by first drying and first calcination. The composite support is impregnated in a mixed salt solution for the second time, and then subjected to a second drying and a second calcination to obtain a denitrification catalyst; the solutes in the mixed salt solution include vanadate, tungstate and molybdate.

6. The preparation method according to claim 5, characterized in that, The Zr salt in the Zr salt solution is zirconium nitrate; the mass ratio of TiO2 to zirconium nitrate is 2:1.2~1.

6.

7. The preparation method according to claim 5 or 6, characterized in that, The first calcination temperature is 550~600℃, and the holding time is 3~6h.

8. The preparation method according to claim 5, characterized in that, The vanadate is ammonium metavanadate, and the mass ratio of the composite support to ammonium metavanadate is 2:0.01~0.02; the tungstate is ammonium tungstate, and the mass ratio of the composite support to ammonium tungstate is 2:0.18~0.2; the molybdate is ammonium molybdate, and the mass ratio of the composite support to ammonium molybdate is 2:0.01~0.

06.

9. The preparation method according to claim 5 or 8, characterized in that, The second calcination temperature is 550~600℃, and the holding time is 3~6h.

10. A denitrification system inside a catalytic cracking unit, comprising a catalytic cracking reactor, wherein the catalytic cracking reactor is provided with a catalytic cracking feedstock inlet at the top and a catalytic cracking product outlet at the bottom, the inlet and outlet being connected by a catalytic cracking pipeline; the catalytic cracking reactor is further provided with a heating flue gas inlet and a flue gas outlet for heating the catalytic cracking pipeline; A denitrification unit is installed in the path through which the heating flue gas passes inside the catalytic cracking reactor; The denitrification unit includes an ammonia injection pipe and a bed of denitrification catalyst arranged sequentially in the direction of the heated flue gas passage; the denitrification catalyst is the denitrification catalyst according to any one of claims 1 to 4 or the denitrification catalyst obtained by the preparation method according to any one of claims 5 to 9.

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