Flue gas denitration catalyst as well as preparation method and application thereof

Abstract

The invention provides a flue gas denitration catalyst as well as a preparation method and application thereof. The flue gas denitration catalyst comprises a carrier and an active component, the carrier comprises porous solid solution microspheres composed of TiO2, CeO2 and SiO2, and the active components comprise CuO and FeO; the specific surface area of the flue gas denitration catalyst is not less than 62.7 m < 2 > / g; in the flue gas denitration reaction of the flue gas denitration catalyst, the conversion rate of NOx is not lower than 75.0% at the temperature of 400-500 DEG C. The flue gas denitration catalyst has relatively high specific surface area and high-temperature thermal stability, and the conversion rate of NOx in a flue gas denitration reaction can be remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the field of catalysts, and relates to a flue gas denitration catalyst, in particular to a flue gas denitration catalyst, a preparation method thereof and an application thereof. Background Art

[0002] Nitrogen oxides (NO x ) are the main air pollutants. They not only cause pollution to the natural environment such as photochemical smog and greenhouse effect, but also seriously endanger human health. Reducing the generation and emission of nitrogen oxide waste gas has become one of the main issues that people are increasingly concerned about.

[0003] Selective catalytic reduction (SCR) is a currently mature and most widely used NO x emission control method. Under the action of a catalyst, a reducing agent gas is injected into the flue gas to reduce NO x to N 2 and H 2 O. Among them, the SCR technology using NH 3 as a reducing agent has been applied to the emission control of industrial and stationary source NO x . However, the NH 3 -SCR technology still has technical defects: ammonia has certain dangers in storage, transportation and leakage problems; therefore, it is necessary to find a more economical, long-lasting and environmentally friendly denitration technology to replace NH 3 -SCR. CO is commonly present in the flue gas of ethylene cracking furnaces, with rich sources, stable properties, and a concentration higher than that of NO x . Therefore, using CO as a reducing agent to selectively reduce nitrogen oxides can also achieve the effect of treating waste with waste, and is expected to solve the defects of the NH 3 -SCR technology, with broad application prospects and great economic value. The denitration catalyst, as the core of the CO-SCR technology, its performance largely affects the denitration effect. However, currently, traditional industrial denitration catalysts still have the problem of a relatively small specific surface area, resulting in poor denitration efficiency.

[0004] Therefore, in view of the above defects, it is urgent to study a non-ammonia reduction flue gas denitration catalyst with a high specific surface area and high denitration efficiency. Summary of the Invention

[0005] In view of the above defects, the present invention provides a flue gas denitration catalyst, which has a relatively high specific surface area and a NO x conversion rate.

[0006] The present invention provides a preparation method of a flue gas denitration catalyst. The flue gas denitration catalyst prepared by this preparation method has a relatively high specific surface area and can achieve a relatively high NO x conversion rate.

[0007] The present invention provides a flue gas denitration method. Since the catalyst used in this method is the above-mentioned flue gas denitration catalyst or the flue gas denitration catalyst prepared by the above-mentioned preparation method, the denitration efficiency of this method is relatively high.

[0008] The present invention provides a flue gas denitration catalyst, which comprises a carrier and an active component; the carrier comprises a porous solid solution microsphere composed of TiO 2 , CeO 2 and SiO 2 , and the active component comprises CuO and FeO;

[0009] The specific surface area of the flue gas denitration catalyst is not less than 62.7 m 2 / g;

[0010] In the flue gas denitration reaction of the flue gas denitration catalyst, at 400-500 °C, the conversion rate of NO x is not less than 75.0%.

[0011] Furthermore, the mass ratio of CeO 2 to TiO 2 is (0.5-8):100, and the mass ratio of SiO 2 to TiO 2 is (0.5-5):100;

[0012] and / or, the mass ratio of CuO to TiO 2 is (1.0-6):100;

[0013] and / or, the mass ratio of FeO to TiO 2 is (0.5-3):100.

[0014] Furthermore, the flue gas denitration catalyst is a honeycomb flue gas denitration catalyst.

[0015] The present invention provides a preparation method of a flue gas denitration catalyst, which comprises the following steps:

[0016] (1) Mix a titanium source precursor, a cerium source precursor, a silicon source precursor and an organic alcohol to obtain a first mixed solution, and carry out a hydrothermal reaction to obtain an intermediate product;

[0017] (2) Wash, solid-liquid separate, dry and calcine the intermediate product to obtain the porous solid solution microsphere; wherein, the calcination temperature is 400-600 °C and the calcination time is 1-5 h;

[0018] (3) Mix the porous solid solution microspheres with a copper source precursor, an iron source precursor, an extrusion aid, a pore former, glass fibers, and water to obtain a mud-like substance, extrude it to form a green body, and obtain the flue gas denitration catalyst after drying and calcination.

[0019] Further, in step (1), the titanium source precursor is TiO 2 calculated as, the cerium source precursor is CeO 2 calculated as, the silicon source precursor is SiO 2 calculated as. The mass ratio of the cerium source precursor to the titanium source precursor is (0.5 - 8):100, the mass ratio of the silicon source precursor to the titanium source precursor is (0.5 - 5):100, and the volume ratio of the organic alcohol to the titanium source precursor is (2 - 10):100;

[0020] Further, in step (1), the temperature of the hydrothermal reaction is 140 - 220 °C, and the reaction time is 6 - 30 h;

[0021] And / or, in step (2), the drying temperature is 60 - 150 °C, and the drying time is 1 - 8 h.

[0022] Further, in step (3), the copper source precursor is CuO, the iron source precursor is FeO, the titanium source precursor is TiO 2 calculated as. The mass ratio of the copper source precursor to the titanium source precursor is (1.0 - 6):100;

[0023] And / or, the mass ratio of the iron source precursor to the titanium source precursor is (0.5 - 3):100;

[0024] And / or, the mass ratio of the extrusion aid to the titanium source precursor is (0.5 - 3):100;

[0025] And / or, the mass ratio of the pore former to the titanium source precursor is (0.5 - 3):100;

[0026] And / or, the mass ratio of the glass fibers to the titanium source precursor is (2 - 8):100;

[0027] And / or, the water content of the mud-like substance is 22 - 38 wt%.

[0028] Further, in step (3), the drying temperature is 20 - 90 °C, the drying time is 5 - 18 days, and the relative humidity of the air under the drying environmental conditions is 30 - 99%;

[0029] And / or, the calcination temperature is 460 - 650 °C, and the calcination time is 15 - 45 h.

[0030] Further, the cerium source precursor includes at least one of cerium nitrate, cerium sulfate, cerium chloride, and cerium acetate;

[0031] and / or, the titanium source precursor includes tetra-isopropyl titanate and / or tetra-butyl titanate;

[0032] and / or, the silicon source precursor includes silicate;

[0033] and / or, the organic alcohol includes at least one of ethanol, ethylene glycol, glycerol, isopropyl alcohol, and butanol;

[0034] and / or, the copper source precursor includes at least one of copper nitrate, copper chloride, and copper sulfate;

[0035] and / or, the iron source precursor includes at least one of iron chloride, iron sulfate, and iron nitrate;

[0036] and / or, the extrusion aid includes stearic acid and / or glycerol;

[0037] and / or, the pore former includes polyethylene oxide and / or polymethyl methacrylate.

[0038] The present invention provides a flue gas denitrification method, which uses the flue gas denitrification catalyst described in any one of the above items, or the flue gas denitrification catalyst prepared by the preparation method described in any one of the above items in the flue gas denitrification reaction.

[0039] The flue gas denitrification catalyst of the present invention includes a carrier and an active component. The carrier includes a porous solid solution microsphere composed of TiO 2 , CeO 2 and SiO 2 . The active component includes CuO and FeO. This porous solid solution microsphere is a modified TiO 2 doped with CeO 2 and SiO 2 , and has a new Ti-Ce-Si solid solution structure, which can increase the lattice defects and specific surface area of TiO 2 . It can not only make the active components CuO and FeO more uniformly dispersed in the porous solid solution microsphere and be tightly connected with the porous solid solution microsphere, giving full play to the catalyst activity to a greater extent and improving the denitrification efficiency; but also effectively increase the specific surface area of the flue gas denitrification catalyst, making it not less than 62.7 m 2 / g. Therefore, in the flue gas denitrification reaction, the conversion rate of NO x is not less than 75.0% at 400 - 500 °C. Detailed implementation manners

[0040] To make the objectives, technical solutions and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. 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 scope of protection of the present invention.

[0041] In a first aspect of the present invention, a flue gas denitration catalyst is provided. The flue gas denitration catalyst includes a carrier and an active component; the carrier includes a porous solid solution microsphere composed of TiO 2 , CeO 2 and SiO 2 , and the active component includes CuO and FeO;

[0042] The specific surface area of the flue gas denitration catalyst is not less than 62.7 m 2 / g;

[0043] In the flue gas denitration reaction, the conversion rate of NO x is not less than 75.0% at 400 - 500 °C.

[0044] The conversion rate of NO x in the present invention being not less than 75.0% means that when the flue gas denitration catalyst in the present invention is used in the flue gas denitration reaction, it specifically includes:

[0045] NOx conversion rate evaluation conditions: space velocity 3500 h -1 , reaction temperature 450 °C, inlet NO x being 400 mg / Nm 3 , SO 2 being 30 mg / Nm 3 , CO / NO x ratio being 1, and O 2 content being 3.0% (v).

[0046] Source of raw material gas: NO and CO are standard gases with specifications of 5.0% (v), N 2 gas is for balance, and the manufacturer is Dalian Dete Gas Co., Ltd.; O 2 comes from the public utility air pipe network with a pressure of 0.4 - 0.6 MPa; N 2 comes from the public utility nitrogen pipe network with a purity of 99.0% (v) and a pressure of 0.4 - 0.6 MPa.

[0047] NO concentration measurement method: flue gas continuous online analyzer, Siemens ULTRAMAT23.

[0048] The flue gas denitration catalyst of the present invention comprises a carrier and an active component. The carrier comprises a porous solid solution microsphere composed of TiO 2 , CeO 2 and SiO 2 , and the active component comprises CuO and FeO. Since the atomic radius of Si 4+ is smaller than that of Ti 4+ , Si 4+ displaces Ti 2 in TiO 4+ and combines with O. Meanwhile, Ce 4+ also combines with O to form a new Ti-Ce-Si solid solution structure. This structure can increase the lattice defects and specific surface area of TiO 2 . The lattice defects can form oxygen vacancies, which can not only cooperate with CuO and FeO to improve the dispersion uniformity of the active components CuO and FeO in the porous solid solution microsphere, increase the active sites of the catalyst, and the tightness of the connection between the active components and the porous solid solution microsphere, enabling the catalyst to exert its catalytic activity to a greater extent and improve the denitration efficiency; but also effectively increase the specific surface area of the flue gas denitration catalyst, making it not less than 62.7 m 2 / g. Furthermore, in the flue gas denitration reaction, the conversion rate of NO x is not less than 75.0% at 400 - 500 °C.

[0049] In addition, since the Ti-Ce-Si solid solution structure can also significantly improve the high-temperature thermal stability of TiO 2 , the catalyst can still maintain a high activity at 400 - 500 °C. Meanwhile, the Ce element therein can not only improve the resistance of the catalyst to alkali metal and alkaline earth metal poisoning, but also form a synergistic effect with the Cu element and Fe element to further improve the catalytic efficiency and alkali metal poisoning resistance of the catalyst. Moreover, the active component of the flue gas denitration catalyst in the present invention does not include vanadium element, so the generation amount of SO 2 converted into SO 3 can be reduced, the generation amount of sulfate scale can be decreased, and the normal operation condition of the subsequent low-temperature economizer can be improved.

[0050] In a specific embodiment, the mass ratio of CeO 2 to TiO 2 is (0.5 - 8):100, and the mass ratio of SiO 2 to TiO 2 is (0.5 - 5):100. Within this range, TiO 2The degree of lattice distortion is appropriate, resulting in a relatively high strength of the formed crystal, which is not easily damaged, and can effectively increase the specific surface area of the catalyst. At the same time, it can also better synergize the porous solid solution microspheres with CuO and FeO, contributing to improving the uniformity of the distribution of active components and enhancing the catalytic efficiency.

[0051] Further, the mass ratio of CeO 2 to TiO 2 is (1 - 5):100, and the mass ratio of SiO 2 to TiO 2 is (0.5 - 3):100.

[0052] In a specific embodiment, the mass ratio of CuO to TiO 2 is (1.0 - 6):100. Within this range, the synergistic effect between the Ti-Ce-Si solid solution structure and Cu and Fe can be further enhanced, enabling the catalyst to have higher catalytic efficiency. At the same time, the amount of Cu used is less, which can save costs to a certain extent.

[0053] In a specific embodiment, the mass ratio of FeO to TiO 2 is (0.5 - 3):100. Within this range, the new Ti-Ce-Si solid solution structure can better synergize with Cu and Fe, further improving the dispersion uniformity of the active components CuO and FeO in the porous solid solution microspheres, and effectively enhancing the catalytic efficiency of the catalyst in the flue gas denitrification reaction.

[0054] In a specific embodiment, the flue gas denitrification catalyst is a honeycomb flue gas denitrification catalyst. At this time, the honeycomb flue gas denitrification catalyst can more efficiently convert NO in the waste gas x into harmless nitrogen and water vapor during the catalytic reaction, further increasing the conversion rate of NO x .

[0055] The second aspect of the present invention provides a method for preparing a flue gas denitrification catalyst, including the following steps:

[0056] (1) Mix a titanium source precursor, a cerium source precursor, a silicon source precursor with an organic alcohol to obtain a first mixed solution, and carry out a hydrothermal reaction to obtain an intermediate product;

[0057] (2) Wash, separate the solid and liquid, dry, and calcine the intermediate product to obtain porous solid solution microspheres; wherein, the calcination temperature is 400 - 600 °C, and the calcination time is 1 - 5 h;

[0058] (3) Mix the porous solid solution microspheres with a copper source precursor, an iron source precursor, an extrusion aid, a pore former, glass fiber, and water to obtain a paste, extrude to form a green body, and obtain the flue gas denitrification catalyst after drying and calcination.

[0059] Specifically, in step (1), a titanium source precursor based on TiO 2 calculated, a cerium source precursor based on CeO 2 calculated, a silicon source precursor based on SiO 2 calculated and an organic alcohol are mixed to obtain a first mixed solution, and a hydrothermal reaction is carried out to obtain an intermediate product.

[0060] The present invention does not specifically limit the ratios among the titanium source precursor, the cerium source precursor, the silicon source precursor and the organic alcohol, nor the temperature and time of the hydrothermal reaction, as long as a porous solid solution microsphere can be prepared, and then a flue gas denitration catalyst with a specific surface area of not less than 62.7 m 2 / g can be prepared, and in the flue gas denitration reaction of this catalyst, at 400-500 °C, the conversion rate of NO x is not less than 75.0% is sufficient.

[0061] The present invention does not specifically limit the sources of the titanium source precursor, the cerium source precursor, the silicon source precursor and the organic alcohol, and commercially available products or products prepared by conventional preparation methods well-known to those skilled in the art can be used.

[0062] The titanium source precursor of the present invention refers to a raw material providing Ti element, the silicon source precursor refers to a raw material providing Si element, and the cerium source precursor refers to a raw material providing Ce element. As long as it contains the target element (Ti, Si, Ce), it belongs to the scope of the present invention.

[0063] The present invention does not specifically limit the type of the organic alcohol, as long as it can completely dissolve the titanium source precursor, the silicon source precursor and the cerium source precursor to form a mixed solution.

[0064] The present invention does not specifically limit the mixing method, as long as the titanium source precursor, the zirconium source precursor and the cerium source precursor are completely dissolved in the organic alcohol. For example, mixing can be carried out by stirring or ultrasonic oscillation.

[0065] In step (2), after the intermediate product is washed, solid-liquid separated and dried, it is calcined at 400-600 °C for 1-5 h to obtain a porous solid solution microsphere.

[0066] Further, the calcination temperature is 450-550 °C.

[0067] The present invention does not specifically limit the washing method, as long as the intermediate product is washed clean.

[0068] The present invention does not specifically limit the method of solid-liquid separation. For example, solid-liquid separation can be carried out by filtration and / or centrifugal separation.

[0069] The present invention does not specifically limit the temperature and time during the drying process, as long as the moisture in the separated solid phase is completely evaporated.

[0070] In step (3), the porous solid solution microspheres are mixed with a copper source precursor in terms of CuO, an iron source precursor in terms of FeO, an extrusion aid, a pore-forming agent, glass fibers, and water to obtain a paste, which is extruded to form a green body, and then dried and calcined to obtain a flue gas denitration catalyst.

[0071] Furthermore, during the mixing process, the copper source precursor, the iron source precursor, the extrusion aid, the pore-forming agent, the glass fibers, and water can be more uniformly mixed by stirring.

[0072] The copper source precursor in the present invention refers to a raw material that provides Cu element, and the iron source precursor refers to a raw material that provides Fe element. As long as it contains the target element (Cu, Fe), it falls within the scope of the present invention.

[0073] The present invention does not specifically limit the dosages of the copper source precursor, the iron source precursor, the extrusion aid, the pore-forming agent, and the glass fibers.

[0074] The present invention does not specifically limit the types of the extrusion aid, the pore-forming agent, and the glass fibers, and those commonly used by those skilled in the art can be adopted.

[0075] The present invention does not specifically limit the sources of the copper source precursor, the iron source precursor, the extrusion aid, the pore-forming agent, and the glass fibers, and commercially available products or products prepared by conventional preparation methods well-known to those skilled in the art can be adopted.

[0076] The present invention does not specifically limit the water content of the paste, as long as the paste can be extruded and the extruded green body meets the molding requirements. For example, the water content is 15-40 wt%.

[0077] The present invention does not specifically limit the drying temperature and drying time, as well as the calcination temperature and calcination time.

[0078] In the preparation method of the flue gas denitration catalyst in the present invention, first, CeO and SiO are doped into TiO by the hydrothermal method. In the TiO lattice, Ti is easily replaced by Si with a smaller atomic radius to form a new Ti-Si-Ce solid solution structure. Secondly, by calcining the product after the hydrothermal reaction, the lattice defects of the doped TiO become more stable, and the TiO 2 in 2 is doped with 2 CeO 2 and SiO 4+ and SiO 4+ The lattice defects of the doped TiO are made more stable, and the TiO 2 is increased. 2The lattice defects and specific surface area of the substrate can not only make the active components more uniformly dispersed, increase the active sites of the catalyst, improve the connection tightness between the active components and the porous solid solution microspheres, but also increase the specific surface area of the catalyst to be not less than 62.7 m 2 / g, which helps to fully exert the catalytic activity of the catalyst and improve the denitrification efficiency; through the above preparation method, the denitrification efficiency of the catalyst can be comprehensively improved, so that in the flue gas denitrification reaction, the NO x conversion rate at 400-500 °C is not less than 75.0%.

[0079] In addition, the newly formed Ti-Si-Ce solid solution structure can also significantly improve the thermal stability of the porous solid solution microspheres, thereby broadening the working temperature range of the catalyst, enabling the catalyst to maintain high activity in a high-temperature environment and having a high NO x conversion rate.

[0080] In a specific embodiment, in step (1), based on TiO 2 for the titanium source precursor, based on CeO 2 for the cerium source precursor, and based on SiO 2 for the silicon source precursor, the mass ratio of the cerium source precursor to the titanium source precursor is (0.5-8):100, the mass ratio of the silicon source precursor to the titanium source precursor is (0.5-5):100, and the volume ratio of the organic alcohol to the titanium source precursor is (2-10):100. Within this range, it helps to make the mass ratio of CeO 2 to TiO 2 in the porous solid solution microspheres be between (0.5-8):100, and the mass ratio of SiO 2 to TiO 2 be between (0.5-5):100, thereby effectively enhancing the strength of the porous solid solution microspheres, the specific surface area of the catalyst, and improving the distribution uniformity of the active components in the porous solid solution microspheres, thus improving the catalytic efficiency of the catalyst; at the same time, when the mass ratio of the organic alcohol to the titanium source precursor is within the aforementioned range, it can provide sufficient hydroxyl groups to participate in the reaction, improve the reaction degree, and make the formed porous solid solution microspheres more complete.

[0081] In a specific embodiment, in step (1), the hydrothermal reaction temperature is 140-220 °C, and the reaction time is 6-30 h. Within this range, it is possible to avoid an increase in side reactions due to too fast reaction rate, and at the same time, it will not lead to a decrease in efficiency due to too low reaction temperature.

[0082] Furthermore, the hydrothermal reaction temperature is 150-180 °C, and the reaction time is 15-24 h.

[0083] In a specific embodiment, in step (2), the drying temperature is 60 to 150 °C, and the drying time is 1 to 8 h. Within this range, the microspheres can be prevented from cracking, the obtained porous solid solution microspheres have a good morphology, and the drying efficiency can be improved while reducing high energy consumption.

[0084] Further, the drying temperature is 80 to 110 °C.

[0085] In a specific embodiment, in step (3), the copper source precursor is calculated as CuO, the iron source precursor is calculated as FeO, and the titanium source precursor is calculated as TiO 2 The mass ratio of the copper source precursor to the titanium source precursor is (1.0 - 6):100. Within this range, it helps to make the mass ratio of CuO to TiO in the obtained porous solid solution microspheres 2 between (1.0 - 6):100, thereby effectively improving the synergistic effect between the Ti-Ce-Si solid solution structure and Cu and Fe, and enabling the catalyst to have higher catalytic efficiency.

[0086] In a specific embodiment, in step (3), the mass ratio of the iron source precursor to the titanium source precursor is (0.5 - 3):100. Within this range, it helps to make the mass ratio of FeO to TiO in the obtained porous solid solution microspheres 2 between (0.5 - 3):100, enabling the newly formed Ti-Ce-Si solid solution structure to better synergize with Cu and Fe, improving the uniformity of the distribution of the active components in the microspheres, and thus effectively improving the catalytic efficiency.

[0087] In a specific embodiment, in step (3), the mass ratio of the extrusion aid to the titanium source precursor is (0.5 - 3):100. Within this range, it is beneficial for the catalyst to be extruded and formed, and effectively avoids internal cracks in the catalyst during the subsequent calcination process.

[0088] In a specific embodiment, in step (3), the mass ratio of the pore former to the titanium source precursor is (0.5 - 3):100. Within this range, it is beneficial for the formation of suitable pores (including pore size, quantity, and pore structure) inside the catalyst, thereby facilitating the contact, reaction, and mass transfer between the active components and the flue gas during the catalytic reaction process and improving the catalytic efficiency.

[0089] In a specific embodiment, in step (3), the mass ratio of the glass fiber to the titanium source precursor is (2 - 8):100. Within this range, it helps to keep the shape of the catalyst green body intact without cracking (including the ends and inside) during the drying process.

[0090] In a specific embodiment, in step (3), the water content of the mud-like substance is 22 to 38 wt%. Within this range, the catalyst mud blank is easier to extrude and form, avoiding the problem that the mud is not easy to form after extrusion due to too high water content of the mud, long drying time, and cracking of the blank during the drying process; at the same time, it can also prevent the problem of difficult extrusion of the mud due to too high water content and easy cracking of the blank during the extrusion process.

[0091] In a specific embodiment, in step (3), the drying temperature is 20 to 90 °C, the drying time is 5 to 18 days, and the relative humidity of the air under the drying environmental conditions is 30 to 99%. Within this range, it is beneficial to improve the drying efficiency and keep the external shape of the catalyst blank intact during the drying process, avoiding the problems of blank cracking and incomplete external shape caused by too high drying temperature or too low environmental air humidity, and helping to extend the service life of the catalyst.

[0092] In a specific embodiment, in step (3), the calcination temperature is 460 to 650 °C, and the calcination time is 15 to 45 h. Within this range, it can ensure that the catalyst is fully activated, avoiding the problem that the catalyst is not fully activated due to too low calcination temperature or too short calcination time, resulting in low catalytic efficiency; at the same time, it can also prevent the internal pore channels of the catalyst from sintering, the porosity from decreasing, and partial TiO 2 transforming from anatase to rutile, resulting in a decrease in catalytic efficiency.

[0093] In a specific embodiment, the cerium source precursor includes at least one of cerium nitrate, cerium sulfate, cerium chloride, and cerium acetate, preferably cerium nitrate; and / or, the silicon source precursor includes silicate salts, preferably sodium silicate and / or sodium metasilicate; and / or, the organic alcohol includes at least one of ethanol, ethylene glycol, glycerol, isopropyl alcohol, and butanol, preferably ethylene glycol; and / or, the copper source precursor includes at least one of copper nitrate, copper chloride, and copper sulfate, preferably copper nitrate; and / or, the iron source precursor includes at least one of iron chloride, iron sulfate, and iron nitrate, preferably iron nitrate; and / or, the extrusion aid includes stearic acid and / or glycerol; and / or, the pore-forming agent includes polyethylene oxide and / or polymethyl methacrylate. When the foregoing several types of compounds are mixtures of multiple specific compounds respectively, the present invention does not impose excessive limitations on the ratios between the individual specific compounds.

[0094] Furthermore, the present invention does not specifically limit the molecular weights of polyethylene oxide and polymethyl methacrylate. For example, the average molecular weight of polyethylene oxide is 3 million to 8 million, and the number-average molecular weight of polymethyl methacrylate is 100,000 to 1 million.

[0095] In a specific embodiment, in step (3), the green body is a honeycomb catalyst green body. By extruding the green body into a honeycomb catalyst green body, the catalytic efficiency can be improved, and the conversion rate of NO x can be further increased.

[0096] The third aspect of the present invention provides a flue gas denitrification method, using the flue gas denitrification catalyst of the first aspect or the flue gas denitrification catalyst prepared by the preparation method of the second aspect in the flue gas denitrification reaction. Since this flue gas denitrification catalyst has a high specific surface area and thermal stability, at a reaction temperature of 400-500 °C, a high denitrification efficiency can still be achieved, making the conversion rate of NO x not less than 75.0%.

[0097] Hereinafter, the flue gas denitrification catalyst of the present invention will be introduced in detail through specific examples.

[0098] Example 1

[0099] (1) 100 g of tetra-isopropyl titanate calculated based on TiO 2 , 1 g of cerium nitrate calculated based on CeO 2 , 2 g of sodium metasilicate calculated based on SiO 2 and 900 mL of ethylene glycol were mixed and stirred, and then placed in a reaction kettle. Among them, the volume ratio of ethylene glycol to tetra-isopropyl titanate was 2.43:1. Hydrothermal reaction was carried out at a reaction temperature of 180 °C for 15 h to obtain an intermediate product;

[0100] (2) The intermediate product was washed, filtered, then dried at 110 °C for 2 h, and after taking out the sample, it was calcined in an environment of 500 °C for 4 h to obtain porous solid solution microspheres;

[0101] (3) The porous solid solution microspheres were mixed and stirred with 6 g of copper sulfate calculated based on CuO, 0.5 g of iron nitrate calculated based on FeO, 1.0 g of stearic acid, 5.0 g of glass fiber, 1 g of polymethyl methacrylate (number average molecular weight of 100,000) and deionized water to make a mud-like substance containing 36 wt% of water, and extruded to obtain a honeycomb catalyst green body. The green body was dried at 20 °C - 80 °C for 15 days (air relative humidity was 30 - 99%), and then calcined at 550 °C for 30 h to obtain the honeycomb flue gas denitrification catalyst of this example.

[0102] Example 2

[0103] (1) 100 g of tetra-butyl titanate calculated based on TiO 2 , 5 g of cerium nitrate calculated based on CeO 2 , 5 g of sodium metasilicate calculated based on SiO 20.5 g of sodium silicate and 1500 mL of ethylene glycol are mixed and stirred, and then placed in a reaction kettle. Among them, the volume ratio of ethylene glycol to tetra-isopropyl titanate is 3.38:1. Hydrothermal reaction is carried out at a reaction temperature of 180 °C for 15 h to obtain an intermediate product;

[0104] (2) The intermediate product is washed, filtered, then dried at 100 °C for 3 h. After taking out the sample, it is calcined in an environment of 520 °C for 3 h to obtain porous solid solution microspheres;

[0105] (3) The porous solid solution microspheres are mixed and stirred with 5 g of copper nitrate in terms of CuO, 1 g of iron nitrate in terms of FeO, 3 g of stearic acid, 8 g of glass fiber, 2 g of polyethylene oxide (average molecular weight of 3 million) and deionized water to make a mud containing 32 wt% water, and extruded to obtain a honeycomb catalyst green body. The green body is dried at 20 - 70 °C for 13 days (air relative humidity is 30 - 99%), and then calcined at 550 °C for 20 h to obtain the honeycomb flue gas denitration catalyst of this example.

[0106] Example 3

[0107] (1) 100 g of tetra-isopropyl titanate in terms of TiO 2 , 3 g of cerium nitrate in terms of CeO 2 , 2 g of sodium metasilicate in terms of SiO 2 and 2000 mL of ethylene glycol are mixed and stirred, and then placed in a reaction kettle. Among them, the volume ratio of ethylene glycol to tetra-isopropyl titanate is 5.40:1. Hydrothermal reaction is carried out at a reaction temperature of 170 °C for 17 h to obtain an intermediate product;

[0108] (2) The intermediate product is washed, filtered, then dried at 100 °C for 3 h. After taking out the sample, it is calcined in an environment of 460 °C for 4 h to obtain porous solid solution microspheres;

[0109] (3) The porous solid solution microspheres are mixed and stirred with 4 g of copper nitrate in terms of CuO, 2 g of iron nitrate in terms of FeO, 2 g of stearic acid, 4 g of glass fiber, 1 g of polyethylene oxide (average molecular weight of 5 million) and deionized water to make a mud containing 30 wt% water, and extruded to obtain a honeycomb catalyst green body. The green body is dried at 30 - 50 °C for 15 days (air relative humidity is 30 - 99%), and then calcined at 600 °C for 15 h to obtain the honeycomb flue gas denitration catalyst of this example.

[0110] Example 4

[0111] (1) 100 g of tetra-butyl titanate in terms of TiO 2 , 4 g of cerium sulfate in terms of CeO 2 , 4 g of sodium metasilicate in terms of SiO 22 g of sodium silicate and 1800 mL of ethylene glycol were mixed and stirred, and then placed in a reaction kettle. Among them, the volume ratio of ethylene glycol to tetra-isopropyl titanate was 4.06:1. Hydrothermal reaction was carried out at a reaction temperature of 160 °C for 20 h to obtain an intermediate product;

[0112] (2) The intermediate product was washed and filtered, and then dried at 90 °C for 6 h. After taking out the sample, it was calcined in an environment of 500 °C for 4 h to obtain porous solid solution microspheres;

[0113] (3) The porous solid solution microspheres were mixed and stirred with 3 g of copper nitrate in terms of CuO, 2.5 g of iron nitrate in terms of FeO, 2 g of glycerol, 4 g of glass fiber, 1 g of polymethyl methacrylate (number average molecular weight of 200,000) and deionized water to make a mud containing 28 wt% of water. It was extruded to obtain a honeycomb catalyst green body. The green body was dried at 30 - 50 °C for 15 days (air relative humidity was 30 - 99%), and then calcined at 500 °C for 38 h to obtain the honeycomb flue gas denitration catalyst of this example.

[0114] Example 5

[0115] (1) 100 g of tetra-isopropyl titanate in terms of TiO 2 , 5 g of cerium nitrate in terms of CeO 2 , 2 g of sodium silicate in terms of SiO 2 and 900 mL of ethylene glycol were mixed and stirred, and then placed in a reaction kettle. Among them, the volume ratio of ethylene glycol to tetra-isopropyl titanate was 2.43:1. Hydrothermal reaction was carried out at a reaction temperature of 160 °C for 24 h to obtain an intermediate product;

[0116] (2) The intermediate product was washed and filtered, and then dried at 90 °C for 6 h. After taking out the sample, it was calcined in an environment of 490 °C for 4 h to obtain porous solid solution microspheres;

[0117] (3) The porous solid solution microspheres were mixed and stirred with 1 g of copper sulfate in terms of CuO, 3 g of iron nitrate in terms of FeO, 3 g of glycerol, 6 g of glass fiber, 2 g of polyethylene oxide (average molecular weight of 8 million) and deionized water to make a mud containing 27.5 wt% of water. It was extruded to obtain a honeycomb catalyst green body. The green body was dried at 30 - 70 °C for 15 days (air relative humidity was 30 - 99%), and then calcined at 490 °C for 40 h to obtain the honeycomb flue gas denitration catalyst of this example.

[0118] Example 6

[0119] (1) 100 g of tetra-isopropyl titanate in terms of TiO 2 , 8 g of cerium nitrate in terms of CeO 2 , 8 g of sodium silicate in terms of SiO 25 g of sodium metasilicate and 3400 mL of ethylene glycol were mixed and stirred, and then placed in a reaction kettle. Among them, the volume ratio of ethylene glycol to tetra-isopropyl titanate was 9.17:1. Hydrothermal reaction was carried out at a reaction temperature of 220 °C for 6 h to obtain an intermediate product;

[0120] (2) The intermediate product was washed and filtered, and then dried at 150 °C for 1 h. After taking out the sample, it was calcined in an environment of 600 °C for 1 h to obtain porous solid solution microspheres;

[0121] (3) The porous solid solution microspheres were mixed and stirred with 6 g of copper sulfate in terms of CuO, 0.5 g of iron nitrate in terms of FeO, 1.0 g of stearic acid, 2.0 g of glass fiber, 3 g of polymethyl methacrylate (number average molecular weight of 500,000) and deionized water to make a mud containing 36 wt% water. The mud was extruded to obtain a honeycomb catalyst green body. The green body was dried at 20 °C to 80 °C for 15 days (air relative humidity was 30 to 99%), and then calcined at 650 °C for 15 h to obtain the honeycomb flue gas denitration catalyst of this example.

[0122] Example 7

[0123] The preparation method of the honeycomb flue gas denitration catalyst in this example was basically the same as that in Example 1, except that in step (1), the mass of cerium nitrate was adjusted to 0.2 g (in terms of CeO 2 ), and the mass of sodium metasilicate was adjusted to 8 g (in terms of SiO 2 ).

[0124] Example 8

[0125] The preparation method of the honeycomb flue gas denitration catalyst in this example was basically the same as that in Example 1, except that in step (3), the mass of copper sulfate was adjusted to 0.2 g (in terms of CuO).

[0126] Example 9

[0127] The preparation method of the honeycomb flue gas denitration catalyst in this example was basically the same as that in Example 1, except that in step (3), the mass of iron nitrate was adjusted to 0.1 g (in terms of FeO).

[0128] Example 10

[0129] The preparation method of the honeycomb flue gas denitration catalyst in this example was basically the same as that in Example 1, except that in step (3), the mud was extruded to obtain a corrugated plate catalyst green body (thickness 0.5 mm, wave peak height 10 mm, corrugation width 12 mm), and the drying conditions and calcination conditions were the same as those in Example 1.

[0130] Example 11

[0131] The preparation method of the honeycomb flue gas denitration catalyst in this example is basically the same as that in Example 1, except that in step (1), the temperature of the hydrothermal reaction is adjusted to 120 °C and the reaction time is adjusted to 40 h.

[0132] Example 12

[0133] The preparation method of the honeycomb flue gas denitration catalyst in this example is basically the same as that in Example 1, except that in step (2), the drying temperature is adjusted to 40 °C and the drying time is adjusted to 16 h.

[0134] Example 13

[0135] The preparation method of the honeycomb flue gas denitration catalyst in this example is basically the same as that in Example 1, except that in step (3), the mass of the extrusion aid stearic acid is adjusted to 4.0 g.

[0136] Example 14

[0137] The preparation method of the honeycomb flue gas denitration catalyst in this example is basically the same as that in Example 1, except that in step (3), the mass of the pore former polymethyl methacrylate is adjusted to 4 g.

[0138] Example 15

[0139] The preparation method of the honeycomb flue gas denitration catalyst in this example is basically the same as that in Example 1, except that in step (3), the mass of the glass fiber is adjusted to 10.0 g.

[0140] Example 16

[0141] The preparation method of the honeycomb flue gas denitration catalyst in this example is basically the same as that in Example 1, except that in step (3), the water content of the mud is adjusted to 45 wt%.

[0142] Example 17

[0143] The preparation method of the honeycomb flue gas denitration catalyst in this example is basically the same as that in Example 1, except that in step (3), the drying temperature is adjusted to 20 °C to 100 °C and the drying time is adjusted to 20 days.

[0144] Example 18

[0145] The preparation method of the honeycomb flue gas denitration catalyst in this example is basically the same as that in Example 1, except that in step (3), the calcination temperature is adjusted to 430 °C and the calcination time is adjusted to 50 h.

[0146] Comparative Example 1

[0147] The preparation method of the honeycomb flue gas denitration catalyst in this comparative example is basically the same as that in Example 1, except that in step (1), CeO is not doped. 2 and SiO 2 Specifically, 100 g of tetra-isopropyl titanate based on TiO 2 was added to 900 mL of ethylene glycol, mixed and stirred, and then placed in a reaction kettle for hydrothermal reaction. The reaction temperature was 180 °C and the reaction time was 15 h to obtain an intermediate product.

[0148] Comparative Example 2

[0149] The preparation method of the honeycomb flue gas denitration catalyst in this comparative example is basically the same as that in Example 1, except that in step (1), only CeO 2 is doped. Specifically, 100 g of tetra-isopropyl titanate based on TiO 2 , 1 g of cerium nitrate based on CeO 2 were added to 900 mL of ethylene glycol, mixed and stirred, and then placed in a reaction kettle for hydrothermal reaction. The reaction temperature was 180 °C and the reaction time was 15 h to obtain an intermediate product.

[0150] Comparative Example 3

[0151] The preparation method of the honeycomb flue gas denitration catalyst in this comparative example is basically the same as that in Example 1, except that in step (1), only SiO 2 is doped. Specifically, 100 g of tetra-isopropyl titanate based on TiO 2 , 2 g of sodium metasilicate based on SiO 2 were added to 900 mL of ethylene glycol, mixed and stirred, and then placed in a reaction kettle for hydrothermal reaction. The reaction temperature was 180 °C and the reaction time was 15 h to obtain an intermediate product.

[0152] Test Example

[0153] The flue gas denitration catalysts prepared in the above examples and comparative examples were applied to the flue gas denitration reaction, and the specific surface area and NO x conversion rate of the catalysts were tested. The specific conditions were as follows:

[0154] NOx conversion rate evaluation conditions: space velocity 3500 h -1 , reaction temperature 450 °C, inlet NO x was 400 mg / Nm 3 , SO 2 was 30 mg / Nm 3 , CO / NO x ratio was 1, O 2 content was 3.0% (v).

[0155] Source of feed gas: Standard gases are used for NO and CO, both with a specification of 5.0% (v), and N 2 gas balance, and the manufacturer is Dalian Dete Gas Co., Ltd.; O 2 comes from the utility air pipe network, with a pressure of 0.4 - 0.6 MPa; N 2 comes from the utility nitrogen pipe network, with a purity of 99.0% (v) and a pressure of 0.4 - 0.6 MPa.

[0156] Method for NO concentration measurement: Flue gas continuous online analyzer, Siemens ULTRAMAT23.

[0157] Method for specific surface area test: BET adsorption method. The test results are shown in Table 1.

[0158] Table 1

[0159]

[0160]

[0161] As can be seen from Table 1:

[0162] The flue gas denitration catalysts in Examples 1 - 18 have a higher NO x conversion rate compared to the flue gas denitration catalysts in Comparative Examples 1 - 3, with a maximum of up to 78.3%, while the maximum NO x conversion rate in Comparative Examples 1 - 3 is only 69.7% at most. It can be seen from this that the flue gas denitration catalyst of the present invention can significantly improve the NO x conversion rate at high temperatures.

[0163] Finally, it should be noted that: The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: They can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flue gas denitration catalyst, characterized in that: The flue gas denitration catalyst comprises a carrier and an active component; the carrier comprises porous solid solution microspheres composed of TiO2, CeO2 and SiO2, and the active component comprises CuO and FeO; The specific surface area of ​​the flue gas denitration catalyst is not less than 62.7 m 2 / g; The flue gas denitration catalyst is used in the flue gas denitration reaction at 400-500°C to reduce NO x The conversion rate is not less than 75.0%.

2. The flue gas denitration catalyst according to claim 1, characterized in that: The mass ratio of CeO2 to TiO2 is (0.5-8):100, and the mass ratio of SiO2 to TiO2 is (0.5-5):100; And / or, the mass ratio of the CuO to the TiO2 is (1.0-6):100; And / or, the mass ratio of the FeO to the TiO2 is (0.5-3):

100.

3. The flue gas denitration catalyst according to claim 1 or 2, characterized in that: The flue gas denitration catalyst is a honeycomb type flue gas denitration catalyst.

4. A method for preparing a flue gas denitration catalyst according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) mixing a titanium source precursor, a cerium source precursor, a silicon source precursor and an organic alcohol to obtain a first mixed solution, and performing a hydrothermal reaction to obtain an intermediate product; (2) washing, solid-liquid separation, drying and calcining the intermediate product to obtain the porous solid solution microspheres; wherein the calcination temperature is 400 to 600° C. and the calcination time is 1 to 5 hours; (3) The porous solid solution microspheres are mixed with a copper source precursor, an iron source precursor, an extrusion aid, a pore-forming agent, glass fiber and water to obtain a sludge, which is then extruded to form a green body, which is then dried and calcined to obtain the flue gas denitration catalyst.

5. The method for preparing a flue gas denitration catalyst according to claim 4, characterized in that: In step (1), the titanium source precursor is calculated as TiO2, the cerium source precursor is calculated as CeO2, and the silicon source precursor is calculated as SiO2. The mass ratio of the cerium source precursor to the titanium source precursor is (0.5-8):100, the mass ratio of the silicon source precursor to the titanium source precursor is (0.5-5):100, and the volume ratio of the organic alcohol to the titanium source precursor is (2-10):

1.

6. The method for preparing a flue gas denitration catalyst according to claim 4 or 5, characterized in that: In step (1), the temperature of the hydrothermal reaction is 140 to 220° C., and the reaction time is 6 to 30 hours; And / or, in step (2), the drying temperature is 60 to 150° C. and the drying time is 1 to 8 hours.

7. The method for preparing a flue gas denitration catalyst according to any one of claims 4 to 6, characterized in that: In step (3), the copper source precursor is calculated as CuO, the iron source precursor is calculated as FeO, the titanium source precursor is calculated as TiO2, and the mass ratio of the copper source precursor to the titanium source precursor is (1-6):100; And / or, the mass ratio of the iron source precursor to the titanium source precursor is (0.5-3):100; And / or, the mass ratio of the extrusion aid to the titanium source precursor is (0.5-3):100; And / or, the mass ratio of the pore former to the titanium source precursor is (0.5-3):100; And / or, the mass ratio of the glass fiber to the titanium source precursor is (2-8):100; And / or, the water content of the mud is 22-38wt%.

8. The method for preparing a flue gas denitration catalyst according to any one of claims 4 to 7, characterized in that: In step (3), the drying temperature is 20 to 90° C., the drying time is 5 to 18 days, and the relative humidity of the air under the drying environment is 30 to 99%; And / or, the calcination temperature is 460-650° C., and the calcination time is 15-45 hours.

9. The method for preparing a flue gas denitration catalyst according to any one of claims 4 to 8, characterized in that: The cerium source precursor includes at least one of cerium nitrate, cerium sulfate, cerium chloride, and cerium acetate; And / or, the titanium source precursor includes tetraisopropyl titanate and / or tetrabutyl titanate; and / or, the silicon source precursor comprises silicates; And / or, the organic alcohol includes at least one of ethanol, ethylene glycol, glycerol, isopropanol, and butanol; And / or, the copper source precursor includes at least one of copper nitrate, copper chloride, and copper sulfate; And / or, the iron source precursor includes at least one of ferric chloride, ferric sulfate, and ferric nitrate; and / or, the extrusion aid comprises stearic acid and / or glycerol; And / or, the pore former includes polyethylene oxide and / or polymethyl methacrylate.

10. A flue gas denitrification method, characterized in that: The flue gas denitration catalyst according to any one of claims 1 to 3, or the flue gas denitration catalyst prepared by the preparation method according to any one of claims 4 to 9 is used in a flue gas denitration reaction.

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