Ammonia oxidation catalysts, methods of making and using the same, and methods of making 2-cyanopyridines

Abstract

The application provides an ammonia oxidation catalyst, a preparation method and application thereof, and a preparation method of 2-cyanopyridine, the catalyst comprises a carrier, an active component and an auxiliary component, the active component elements comprise V and Ti; the auxiliary component elements comprise one or more of non-metal elements, alkali metal elements and group VIB elements; only diffraction peaks of TiO2 crystal phase exist in the XRD pattern of the catalyst, and other active components and auxiliary components are distributed on the surface of TiO2 in the state of monolayer. The catalyst is particularly suitable for ammonia oxidation reaction, and is especially applied to the preparation of 2-cyanopyridine through ammonia oxidation, the yield of 2-cyanopyridine is all above 91%, and the highest yield can reach 92.8%, and an excellent technical effect is achieved.

Description

Technical Field

[0001] This invention relates to ammonia oxidation catalysts, their preparation methods and applications, and methods for preparing 2-cyanopyridine. Background Technology

[0002] Nitrogen heterocyclic and benzene ring cyano compounds have wide applications in pharmaceuticals, pesticides, and food. For example, 3-cyanopyridine is used to prepare nicotinic acid and nicotinamide, both essential components of B vitamins in organisms; aromatic nitriles are important intermediates in the pesticide and flame retardant industries. Traditional industrial production of nitrile compounds relies on batch reactors, which are simple, convenient, and flexible, suitable for small-scale production. However, this method suffers from low product yield, low purity, high wastewater generation, high energy consumption, harsh working environments, and high labor intensity. Therefore, the search for greener, more efficient, environmentally friendly, and more economical reaction processes is urgently needed.

[0003] Currently, several domestic companies, including Guangzhou Nansha Longsha Co., Ltd., Zhejiang Brothers Technology Co., Ltd., Hebei Yano Biochemical Co., Ltd., Anhui Hongtaiyang Biochemical Co., Ltd., and Shandong Hongda Biotechnology Co., Ltd., have industrialized the gas-phase ammoxidation of 3-methylpyridine to produce 3-cyanopyridine, achieving good economic returns. 2-Methylpyridine differs from 3-methylpyridine; the methyl group in 2-methylpyridine is closer to the electron-withdrawing nitrogen atom. During ammoxidation, the methyl oxidation intermediate is very unstable, resulting in generally low yields of 2-cyanopyridine produced by ammoxidation. Currently, the synthesis methods for 2-cyanopyridine include batch reactors and ammoxidation. Batch reactors are complex to operate, have low molecular utilization, and generate significant pollution, making them unsuitable for green and environmentally friendly practices. Ammoxidation is simple, efficient, has high atom utilization, and produces less waste. By selecting a suitable catalyst, the product yield can be significantly improved. Currently, according to literature reports, the highest yield of 2-methylpyridine ammoxidation is 85.6%, but it is understood that the actual yield in domestic industrial production is only around 72%. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem of low product yield in the prior art and to provide an ammonia oxidation catalyst and its preparation method. This catalyst has the advantages of good economy, good product selectivity and high yield of target product.

[0005] This invention suggests that, due to the proximity of the methyl group in the 2-methylpyridine molecule to the nitrogen atom, making it more reactive, the requirements for the catalyst in this reaction are more stringent than those for the ammoxidation of 3-methylpyridine. Therefore, an ammoxidation catalyst with moderate activity and high nitrification capacity has been developed. This catalyst can effectively reduce ring-opening and methyl group loss during the reaction, decrease the formation of carbon dioxide and pyridine, and thus improve the yield of 2-cyanopyridine.

[0006] To achieve the above objectives, the first aspect of the present invention provides an ammonia oxidation catalyst, which includes a support, an active component, and an auxiliary component. The active component includes V and Ti. The auxiliary component includes one or more of non-metallic elements, alkali metal elements, and group VIB elements. The XRD pattern of the catalyst shows only diffraction peaks of the TiO2 crystal phase, and the other active components and auxiliary components are distributed on the TiO2 surface in a monolayer state.

[0007] The second aspect of the present invention provides a method for preparing an ammonia oxidation catalyst, the method comprising: preparing a slurry to be sprayed by a vanadium source, a titanium source, an auxiliary component source, and optionally a polymer binder; spraying the slurry to be sprayed onto a carrier by a spraying method; and then calcining.

[0008] A third aspect of the present invention provides the use of an ammonia oxidation catalyst in the ammonia oxidation preparation of pyridine compounds.

[0009] A fourth aspect of the present invention provides a method for preparing 2-cyanopyridine, the method comprising: contacting a raw material with a catalyst; wherein the catalyst is the ammonia oxidation catalyst described in the present invention.

[0010] Through the above technical solution, the present invention has the following beneficial effects:

[0011] The ammonia oxidation catalyst of this invention comprises a support, an active component, and an auxiliary component. The active component includes V and Ti; the auxiliary component includes one or more of non-metallic elements, alkali metal elements, and Group VIB elements. The XRD pattern of the catalyst shows only diffraction peaks of the TiO2 crystal phase, while the other active and auxiliary components are distributed in a monolayer state on the TiO2 surface. It is particularly suitable for ammonia oxidation reactions, especially when applied to the ammonia oxidation to prepare 2-cyanopyridine. The yield of 2-cyanopyridine is above 91%, and can reach up to 92.8%, achieving excellent technical results.

[0012] According to a preferred embodiment of the present invention, the catalyst of the present invention is prepared by a spraying method, and it was unexpectedly found that the catalyst activity, selectivity and mechanical stability were significantly improved by controlling the calcination time and other factors. Attached Figure Description

[0013] Figure 1 These are the XRD patterns of the catalysts prepared in Example 1 and Comparative Example 1. Detailed Implementation

[0014] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0015] This invention provides an ammonia oxidation catalyst, which includes a support, an active component, and an auxiliary component. The active component includes V and Ti. The auxiliary component includes one or more of non-metallic elements, alkali metal elements, and group VIB elements. The XRD pattern of the catalyst shows only diffraction peaks of the TiO2 crystal phase, while the other active components and auxiliary components are distributed on the TiO2 surface in a monolayer state.

[0016] According to a preferred embodiment of the present invention, the TiO2 crystal phase includes rutile TiO2 and / or anatase TiO2, preferably anatase TiO2 ≥ 90 wt%. Using the aforementioned preferred embodiment can improve the activity of the catalyst.

[0017] In this invention, the support can be a conventional choice in the art. According to a preferred embodiment of the invention, the support is selected from at least one of alumina, silica, and ceramic rings. In this invention, ceramic rings are used as an example in the embodiments, but the invention is not limited to this scope. By employing the aforementioned preferred embodiments, production costs can be reduced while ensuring catalyst performance.

[0018] According to a preferred embodiment of the present invention, the auxiliary component elements include at least two selected from non-metallic elements, alkali metal elements, and Group VIB elements; preferably, the auxiliary component elements simultaneously include non-metallic elements, alkali metal elements, and Group VIB elements. By employing the aforementioned preferred embodiments, the acidity of the catalyst surface can be enhanced, thereby improving the selectivity of the product.

[0019] In this invention, the non-metallic elements in the auxiliary component can be conventionally selected in the art. According to a preferred embodiment of the invention, the non-metallic element is selected from at least one of phosphorus, boron, selenium, and arsenic. By employing the aforementioned preferred embodiment, the number of acid sites on the catalyst surface can be increased, thereby improving the selectivity of the catalyst.

[0020] In this invention, the alkali metal element in the auxiliary component can be a conventional choice in the art. According to a preferred embodiment of the invention, the alkali metal element is selected from at least one of lithium, sodium, potassium, and rubidium. By employing the aforementioned preferred embodiment, the acidity strength of the catalyst surface can be optimized, thereby improving the catalytic performance of the catalyst.

[0021] In this invention, the group VIB element in the auxiliary component can be a conventional choice in the art. According to a preferred embodiment of the invention, the group VIB element is selected from at least one of chromium, molybdenum, and tungsten, but the invention is not limited to this range. By employing the aforementioned preferred embodiments, the lattice oxygen defects on the catalyst surface can be increased, thereby improving the oxidation activity of the catalyst.

[0022] In this invention, the molar ratio of vanadium to titanium can be a conventional choice in the art. According to a preferred embodiment of the invention, the molar ratio of vanadium to titanium is 1:24-32. Using the aforementioned preferred embodiment can improve the dispersion of vanadium on the surface of titanium dioxide, which is beneficial for the formation of a monolayer.

[0023] In this invention, the molar ratio of vanadium to the auxiliary component can be a conventional choice in the art. According to a preferred embodiment of this invention, the molar ratio of vanadium to the auxiliary component is 1:0.1-1.5.

[0024] In this invention, the molar ratio of vanadium to non-metallic elements can be selected over a wide range. According to a preferred embodiment of the invention, the molar ratio of vanadium to non-metallic elements is 1:0.1-0.5. Using the aforementioned preferred embodiment can improve the selectivity of the catalyst.

[0025] In this invention, the molar ratio of vanadium to alkali metal can be selected over a wide range. According to a preferred embodiment of the invention, the molar ratio of vanadium to alkali metal is 1:0.05-0.15. Using the aforementioned preferred embodiment can improve the selectivity of the catalyst.

[0026] In this invention, the molar ratio of vanadium to group VIB elements can be selected over a wide range. According to a preferred embodiment of the invention, the molar ratio of vanadium to group VIB elements is 1:0.15-0.4. Using the aforementioned preferred embodiment can improve the selectivity of the catalyst.

[0027] All ammonia oxidation catalysts with the aforementioned characteristics can be used in this invention, and there are no special requirements for their preparation methods.

[0028] According to a preferred embodiment of the present invention, the preparation method of the ammonia oxidation catalyst includes: preparing a slurry to be sprayed by preparing an active component source and an auxiliary component source by spraying.

[0029] According to a preferred embodiment of the present invention, the solid content of the slurry to be sprayed is 25-40 wt%.

[0030] By employing the aforementioned preferred embodiments, the catalytic performance of the catalyst can be improved.

[0031] According to a preferred embodiment of the present invention, the calcination time for the coating prepared by the spraying method is 10-18 hours, preferably 14-16 hours.

[0032] According to a preferred embodiment of the present invention, the slurry to be sprayed contains a polymer binder, and preferably the mass ratio of the polymer binder to vanadium is (0.05-0.2):1.

[0033] According to a preferred embodiment of the present invention, the polymer binder is selected from at least one of polyvinyl alcohol, polyvinylpyrrolidone and polyacrylamide, preferably polyvinyl alcohol with a degree of polymerization between 25,000 and 150,000. In the examples of the present invention, polyethylene glycol of type 1795 is used as an example, but the present invention is not limited to this range.

[0034] By employing the aforementioned preferred embodiments, the reaction performance of the catalyst can be improved.

[0035] This invention provides a method for preparing an ammonia oxidation catalyst, the method comprising: preparing a slurry to be sprayed by mixing a vanadium source, a titanium source, an auxiliary component source, and optionally a polymer binder; spraying the slurry to be sprayed onto a carrier by a spraying method; and then calcining.

[0036] In this invention, there are no special requirements for the mass ratio of the polymer binder to vanadium. According to a preferred embodiment of the invention, the mass ratio of the polymer binder to vanadium is (0.05-0.2):1. Using the aforementioned preferred embodiment can improve the adhesion of the active component to the ceramic ring surface.

[0037] In this invention, the polymer binder can be a conventional choice in the art. According to a preferred embodiment of the invention, the polymer binder is selected from at least one of polyvinyl alcohol, polyvinylpyrrolidone, and polyacrylamide, preferably polyvinyl alcohol with a degree of polymerization between 25,000 and 150,000. In this invention, polyethylene glycol type 1795 is used as an example in the embodiments, but the invention is not limited to this range. Using the aforementioned preferred embodiments can improve the reaction performance of the catalyst.

[0038] In this invention, the molar ratio of organic acid to vanadium in the slurry to be sprayed can be a conventional choice in the art. According to a preferred embodiment of the invention, the molar ratio of organic acid to vanadium is (3-5):1. Using the aforementioned preferred embodiment can improve the selectivity of the catalyst.

[0039] In this invention, the organic acid can be a conventional choice in the art. According to a preferred embodiment of the invention, the organic acid is selected from at least one of citric acid, malic acid, and oxalic acid. Using the aforementioned preferred embodiment can improve the selectivity of the catalyst.

[0040] According to a preferred embodiment of the present invention, the preparation method of the ammonia oxidation catalyst specifically includes: (1) mixing a vanadium source with an organic acid in a solvent to form a mixture A; (2) mixing mixture A with an auxiliary source to form a mixture B; (3) mixing a titanium source with mixture B to form a mixture C; and (4) mixing a polymer binder with mixture C to form a mixture D as the slurry to be sprayed, and spraying mixture D onto a carrier and calcining it. By adopting the aforementioned preferred embodiment, the catalytic performance of the catalyst can be improved.

[0041] In this invention, there are no special requirements for the calcination conditions in step (4).

[0042] According to a preferred embodiment of the present invention, the calcination time is 10-18 hours, preferably 14-16 hours. Using the aforementioned preferred calcination time allows the active components to be uniformly dispersed on the surface of titanium dioxide, thereby forming a monolayer.

[0043] According to a preferred embodiment of the present invention, the calcination temperature is 400-600°C, preferably 450-550°C.

[0044] By employing the aforementioned preferred embodiments, the catalytic performance of the catalyst can be improved.

[0045] In this invention, there are no special requirements for the conditions of the third and fourth mixing processes.

[0046] In this invention, there are no special requirements for the vanadium source, titanium source, and auxiliary component source. The following is an illustrative description, but it does not limit the scope of this invention. For example, the vanadium source is vanadium pentoxide; the titanium source is titanium dioxide; and the auxiliary component source is phosphoric acid, potassium nitrate, or ammonium molybdate.

[0047] According to a preferred embodiment of the present invention, the temperature of the third and fourth mixtures is 80-90°C.

[0048] According to a preferred embodiment of the present invention, the third mixing time is not particularly required, and the purpose is to achieve uniform mixing. For example, the mixing time can be 8h, 10h, 12h, etc., and those skilled in the art can adjust it according to actual operation.

[0049] According to a preferred embodiment of the present invention, the fourth mixing time is 12h-24h, preferably 15h-20h.

[0050] According to a preferred embodiment of the present invention, the rotational speed of the third and fourth mixing processes is 150-200 rpm.

[0051] By employing the aforementioned preferred embodiments, the selectivity of the catalyst can be improved.

[0052] In this invention, there are no special requirements for the conditions of the first mixing and the second mixing. The purpose is to achieve uniform mixing. For example, it can usually be achieved by slow dripping, heating, stirring and other means. The following is an illustrative description, but it does not limit the scope of the invention.

[0053] According to a preferred embodiment of the present invention, the temperature of the first mixture and the second mixture is 70-85°C.

[0054] According to a preferred embodiment of the present invention, the time for the first mixing and the second mixing is 12-24 hours, preferably 15-20 hours.

[0055] According to a preferred embodiment of the present invention, the rotation speed of the first mixing and the second mixing is 150-200 rpm.

[0056] By employing the aforementioned preferred embodiments, the selectivity of the catalyst can be improved.

[0057] According to a preferred embodiment of the present invention, the molar ratio of the organic acid to vanadium is (3-5):1; preferably, the organic acid is selected from at least one of citric acid, malic acid and oxalic acid.

[0058] By employing the aforementioned preferred embodiments, the selectivity of the catalyst can be improved.

[0059] In this invention, there are no special requirements for the spraying conditions. According to a preferred embodiment of the invention, the spraying temperature is 80-180°C, preferably 100-160°C. Using the aforementioned preferred embodiment can improve the reaction performance of the catalyst.

[0060] In this invention, there are no special requirements for the solvent, as long as it can achieve the purpose of dissolution. It can be carried out with reference to the prior art. In the embodiments of this invention, deionized water is used as an example of solvent, but it should not be limited to the scope of this invention. The amount of deionized water is not limited and can be adjusted according to actual operation. It is only necessary to meet the requirement that the solid content of the slurry to be sprayed is 25-40 wt%.

[0061] The ammonia oxidation catalyst provided by this invention has advantages such as good product selectivity, high yield, and good economy, and can be applied to various ammonia oxidation reactions to prepare pyridine compounds.

[0062] According to a preferred embodiment of the present invention, a method for preparing 2-cyanopyridine is provided, the method comprising: contacting a raw material with a catalyst; wherein the catalyst is the ammonia oxidation catalyst of the present invention.

[0063] According to a preferred embodiment of the invention, the contact is carried out in a fixed-bed reactor.

[0064] According to a preferred embodiment of the present invention, the raw materials include 2-methylpyridine, ammonia, and air, and preferably the molar ratio of 2-methylpyridine, ammonia, and air is 1:(1-10):(1-40).

[0065] By employing the aforementioned preferred embodiments, the product yield can be improved.

[0066] In this invention, there are no special requirements for the contact conditions.

[0067] According to a preferred embodiment of the present invention, the contact temperature is 280-400°C.

[0068] According to a preferred embodiment of the present invention, the contact time is 8-20 hours.

[0069] According to a preferred embodiment of the present invention, the contact pressure is 101-120 kPa.

[0070] By employing the aforementioned preferred embodiments, the product yield can be improved.

[0071] In this invention, the crystal structure of the catalyst was determined by X-ray diffraction (XRD) using a Bruker D8 X-ray powder diffractometer (Germany) with a Cu-Kα ray source and a Kα1 wavelength λ = 1.5405980 angstroms. Nickel filter, operating voltage 40kV, current 40mA, scanning range 2θ=5-80°.

[0072] In this invention, unless otherwise explicitly stated, percentages and contents are all by mass. In the embodiments and comparative examples of this invention, the titanium dioxide used is of the anatase type.

[0073] The yield of 2-cyanopyridine was calculated using the following formula:

[0074]

[0075] The stirring speed in the following examples was 200 rpm; the polyethylene glycol was type 1795 polyethylene glycol.

[0076] In this invention, the solid content of the slurry to be sprayed is: (mass of the stable oxide of the active component after calcination / total weight of the slurry) * 100%.

[0077] Example 1

[0078] Weigh 15g of oxalic acid and 300mL of distilled water into a flask, stir and heat to 85℃ until the oxalic acid is completely dissolved to prepare an oxalic acid solution. Add 5g of vanadium pentoxide to the prepared oxalic acid solution and continue stirring to obtain a vanadium oxalate solution. Add 1.2g of phosphoric acid, 0.6g of potassium nitrate, and 3g of ammonium molybdate to the solution (maintaining the temperature at 85℃). Add 100g of titanium dioxide (90wt% anatase TiO2, the remainder being rutile) to the solution, and continue heating and stirring until homogeneous at 85℃. Dissolve 0.5g of polyvinyl alcohol in 10mL of water and add it to the catalyst precursor slurry (solid content: 35%), and continue heating and stirring for 18h.

[0079] One part of the precursor slurry was loaded into a spray gun and sprayed evenly onto a ceramic ring carrier at a spraying temperature of 120℃. The carrier was then placed in a muffle furnace and calcined at 450℃ for 15 hours. After natural cooling, the catalyst was obtained. The XRD pattern of the catalyst showed only diffraction peaks of the TiO2 crystalline phase; other components were distributed as a monolayer on the TiO2 surface.

[0080] The catalyst particles are 25 mesh, and the method used is... A fixed-bed reactor with a length of 400 mm was used. The catalyst loading was 4 g. The reaction system was at atmospheric pressure and the reaction temperature was 365 °C. The molar ratio of the raw materials was 2-methylpyridine:NH3:air = 1:5:27. The catalyst weight loading (W2-picoline / Wcat) was 0.055 h⁻¹. -1 Evaluation after 2 hours showed that the yield of 2-cyanopyridine was 92.8%.

[0081] Figure 1 The images show the XRD patterns of the catalysts prepared in Example 1 and Comparative Example 1. Figure 1 This indicates that the catalyst prepared according to Example 1 has active components that are uniformly dispersed in a monolayer state on the TiO2 surface.

[0082] Example 2

[0083] Weigh 15g of oxalic acid and 300mL of distilled water into a flask, stir and heat to 85℃ until the oxalic acid is completely dissolved to prepare an oxalic acid solution. Add 5g of vanadium pentoxide to the prepared oxalic acid solution and continue stirring to obtain a vanadium oxalate solution. Add 1.6g of phosphoric acid, 0.3g of potassium nitrate, and 1.8g of ammonium molybdate to the solution (maintaining the temperature at 85℃). Add 100g of titanium dioxide (90wt% anatase TiO2, the remainder being rutile) to the solution, and continue heating and stirring until homogeneous at 85℃. Dissolve 0.5g of polyvinyl alcohol in 10mL of water and add it to the catalyst precursor slurry (solid content: 34%), and continue heating and stirring for 18h.

[0084] One part of the precursor slurry was loaded into a spraying machine and sprayed evenly onto a ceramic ring carrier at a spraying temperature of 140℃. The carrier was then placed in a muffle furnace and calcined at 550℃ for 14 hours. After natural cooling, the catalyst was obtained. The XRD pattern of the catalyst showed only diffraction peaks of the TiO2 crystalline phase; other components were distributed as a monolayer on the TiO2 surface.

[0085] The catalyst particles are 25 mesh, and the method used is... A fixed-bed reactor with a length of 400 mm was used. The catalyst loading was 4 g. The reaction system was at atmospheric pressure and the reaction temperature was 365 °C. The molar ratio of the raw materials was 2-methylpyridine:NH3:air = 1:5:27. The catalyst weight loading (W2-picoline / Wcat) was 0.055 h⁻¹. -1 Evaluation after 2 hours showed that the yield of 2-cyanopyridine was 92.1%.

[0086] Example 3

[0087] Weigh 15g of oxalic acid and 300mL of distilled water into a flask, stir and heat to 85℃ until the oxalic acid is completely dissolved to prepare an oxalic acid solution. Add 5g of vanadium pentoxide to the prepared oxalic acid solution and continue stirring to obtain a vanadium oxalate solution. Add 3g of phosphoric acid, 0.9g of potassium nitrate, and 4.8g of ammonium molybdate to the solution (maintaining the temperature at 85℃). Add 100g of titanium dioxide (90wt% anatase TiO2) to the solution and continue heating and stirring until homogeneous at 85℃. Dissolve 0.5g of polyvinyl alcohol in 10mL of water and add it to the catalyst precursor slurry (solid content: 34%), and continue heating and stirring for 18h.

[0088] One part of the precursor slurry was loaded into a spraying machine and sprayed evenly onto a ceramic ring carrier at a spraying temperature of 170℃. The carrier was then placed in a muffle furnace and calcined at 500℃ for 16 hours. After natural cooling, the catalyst was obtained. The XRD pattern of the catalyst showed only diffraction peaks of the TiO2 crystalline phase; other components were distributed as a monolayer on the TiO2 surface.

[0089] The catalyst particles are 25 mesh, and the method used is... A fixed-bed reactor with a length of 400 mm was used. The catalyst loading was 4 g. The reaction system was at atmospheric pressure and the reaction temperature was 365 °C. The molar ratio of the raw materials was 2-methylpyridine:NH3:air = 1:5:27. The catalyst weight loading (W2-picoline / Wcat) was 0.055 h⁻¹. -1 Evaluation after 2 hours showed that the yield of 2-cyanopyridine was 92.3%.

[0090] Example 4

[0091] All were the same as in Example 1, except that the titanium dioxide used was 60 wt% anatase TiO2 (the remainder being rutile). Under the same evaluation conditions, the evaluation results showed that the yield of 2-cyanopyridine was 82.4%.

[0092] Example 5

[0093] All conditions are the same as in Example 1, except that the amount of vanadium pentoxide added is 2g.

[0094] One part of the precursor slurry was loaded into a spray gun and sprayed evenly onto a ceramic ring carrier at a spraying temperature of 120℃. The carrier was then placed in a muffle furnace and calcined at 450℃ for 15 hours. After natural cooling, the catalyst was obtained. The XRD pattern of the catalyst showed only diffraction peaks of the TiO2 crystalline phase; other components were distributed as a monolayer on the TiO2 surface.

[0095] The catalyst particles are 25 mesh, and the method used is... A fixed-bed reactor with a length of 400 mm was used. The catalyst loading was 4 g. The reaction system was at atmospheric pressure and the reaction temperature was 365 °C. The molar ratio of the raw materials was 2-methylpyridine:NH3:air = 1:5:27. The catalyst weight loading (W2-picoline / Wcat) was 0.055 h⁻¹. -1 Evaluation results over 2 hours showed that the yield of 2-cyanopyridine was 87.6%.

[0096] Example 6

[0097] All conditions were the same as in Example 1, except that the phosphoric acid dosage was 0.3g.

[0098] One part of the precursor slurry was loaded into a spray gun and sprayed evenly onto a ceramic ring carrier at a spraying temperature of 120℃. The carrier was then placed in a muffle furnace and calcined at 450℃ for 15 hours. After natural cooling, the catalyst was obtained. The XRD pattern of the catalyst showed only diffraction peaks of the TiO2 crystalline phase; other components were distributed as a monolayer on the TiO2 surface.

[0099] The catalyst particles are 25 mesh, and the method used is... A fixed-bed reactor with a length of 400 mm was used. The catalyst loading was 4 g. The reaction system was at atmospheric pressure and the reaction temperature was 365 °C. The molar ratio of the raw materials was 2-methylpyridine:NH3:air = 1:5:27. The catalyst weight loading (W2-picoline / Wcat) was 0.055 h⁻¹. -1 Evaluation after 2 hours showed that the yield of 2-cyanopyridine was 90.3%.

[0100] Example 7

[0101] All conditions were the same as in Example 1, except that the amount of potassium nitrate added was 0.15g.

[0102] One part of the precursor slurry was loaded into a spray gun and sprayed evenly onto a ceramic ring carrier at a spraying temperature of 120℃. The carrier was then placed in a muffle furnace and calcined at 450℃ for 15 hours. After natural cooling, the catalyst was obtained. The XRD pattern of the catalyst showed only diffraction peaks of the TiO2 crystalline phase; other components were distributed as a monolayer on the TiO2 surface.

[0103] The catalyst particles are 25 mesh, and the method used is... A fixed-bed reactor with a length of 400 mm was used. The catalyst loading was 4 g. The reaction system was at atmospheric pressure and the reaction temperature was 365 °C. The molar ratio of the raw materials was 2-methylpyridine:NH3:air = 1:5:27. The catalyst weight loading (W2-picoline / Wcat) was 0.055 h⁻¹. -1 Evaluation after 2 hours showed that the yield of 2-cyanopyridine was 90.5%.

[0104] Example 8

[0105] All conditions were the same as in Example 1, except that the amount of ammonium molybdate added was 6g.

[0106] One part of the precursor slurry was loaded into a spray gun and sprayed evenly onto a ceramic ring carrier at a spraying temperature of 120℃. The carrier was then placed in a muffle furnace and calcined at 450℃ for 15 hours. After natural cooling, the catalyst was obtained. The XRD pattern of the catalyst showed only diffraction peaks of the TiO2 crystalline phase; other components were distributed as a monolayer on the TiO2 surface.

[0107] The catalyst particles are 25 mesh, and the method used is... A fixed-bed reactor with a length of 400 mm was used. The catalyst loading was 4 g. The reaction system was at atmospheric pressure and the reaction temperature was 365 °C. The molar ratio of the raw materials was 2-methylpyridine:NH3:air = 1:5:27. The catalyst weight loading (W2-picoline / Wcat) was 0.055 h⁻¹. -1 Evaluation after 2 hours showed that the yield of 2-cyanopyridine was 89.9%.

[0108] Example 9

[0109] Weigh 15g of oxalic acid and 200mL of distilled water into a flask, stir and heat to 85℃ until the oxalic acid is completely dissolved to prepare an oxalic acid solution. Add 5g of vanadium pentoxide to the prepared oxalic acid solution and continue stirring to obtain a vanadium oxalate solution. Add 1.2g of phosphoric acid, 0.6g of potassium nitrate, and 3g of ammonium molybdate to the solution (maintaining the temperature at 85℃). Add 100g of titanium dioxide to the solution and continue heating and stirring until homogeneous at 85℃. Dissolve 0.5g of polyvinyl alcohol in 10mL of water and add it to the catalyst precursor slurry (solid content: 54%), and continue heating and stirring for 18 hours.

[0110] One part of the precursor slurry was loaded into a spraying machine and sprayed evenly onto a ceramic ring carrier at a spraying temperature of 120℃. The carrier was then placed in a muffle furnace and calcined at 450℃ for 15 hours. After natural cooling, the catalyst was obtained.

[0111] The catalyst particles are 25 mesh, and the method used is... A fixed-bed reactor with a length of 400 mm was used. The catalyst loading was 4 g. The reaction system was at atmospheric pressure and the reaction temperature was 365 °C. The molar ratio of the raw materials was 2-methylpyridine:NH3:air = 1:5:27. The catalyst weight loading (W2-picoline / Wcat) was 0.055 h⁻¹. -1 Evaluation after 2 hours showed that the yield of 2-cyanopyridine was 88.5%.

[0112] Example 10

[0113] All conditions were the same as in Example 1, except that the amount of polyvinyl alcohol added was 0.05g.

[0114] One part of the precursor slurry was loaded into a spraying machine and sprayed evenly onto a ceramic ring carrier at a spraying temperature of 120℃. The carrier was then placed in a muffle furnace and calcined at 450℃ for 15 hours. After natural cooling, the catalyst was obtained.

[0115] The catalyst particles are 25 mesh, and the method used is... A fixed-bed reactor with a length of 400 mm was used. The catalyst loading was 4 g. The reaction system was at atmospheric pressure and the reaction temperature was 365 °C. The molar ratio of the raw materials was 2-methylpyridine:NH3:air = 1:5:27. The catalyst weight loading (W2-picoline / Wcat) was 0.055 h⁻¹. -1 Evaluation after 2 hours showed that the yield of 2-cyanopyridine was 89.6%.

[0116] Example 11

[0117] All conditions were the same as in Example 1, except that: one part of the precursor slurry was loaded into a spraying machine, sprayed at 120°C, and evenly sprayed onto a ceramic ring carrier. The carrier was then placed in a muffle furnace and calcined at 450°C for 11 hours, followed by natural cooling to obtain the catalyst.

[0118] The catalyst particles are 25 mesh, and the method used is... A fixed-bed reactor with a length of 400 mm was used. The catalyst loading was 4 g. The reaction system was at atmospheric pressure and the reaction temperature was 365 °C. The molar ratio of the raw materials was 2-methylpyridine:NH3:air = 1:5:27. The catalyst weight loading (W2-picoline / Wcat) was 0.055 h⁻¹. -1 Evaluation after 2 hours showed that the yield of 2-cyanopyridine was 90.2%.

[0119] Example 12

[0120] Weigh 15g of oxalic acid and 300mL of distilled water into a flask, stir and heat to 85℃ until the oxalic acid is completely dissolved to prepare an oxalic acid solution. Add 5g of vanadium pentoxide to the prepared oxalic acid solution and continue stirring to obtain a vanadium oxalate solution. Add 1.2g of phosphoric acid, 0.6g of potassium nitrate, and 3g of ammonium molybdate to the solution (maintaining the temperature at 85℃). Add 100g of titanium dioxide to the solution and continue heating and stirring until homogeneous at 85℃. Dissolve 0.5g of polyvinyl alcohol in 10mL of water and add it to the catalyst precursor slurry (solid content: 35%), and continue heating and stirring for 13 hours.

[0121] One part of the precursor slurry was loaded into a spraying machine and sprayed evenly onto a ceramic ring carrier at a spraying temperature of 120℃. The carrier was then placed in a muffle furnace and calcined at 450℃ for 15 hours. After natural cooling, the catalyst was obtained.

[0122] The catalyst particles are 25 mesh, and the method used is... A fixed-bed reactor with a length of 400 mm was used. The catalyst loading was 4 g. The reaction system was at atmospheric pressure and the reaction temperature was 365 °C. The molar ratio of the raw materials was 2-methylpyridine:NH3:air = 1:5:27. The catalyst weight loading (W2-picoline / Wcat) was 0.055 h⁻¹. -1 Evaluation after 2 hours showed that the yield of 2-cyanopyridine was 90.1%.

[0123] Example 13

[0124] All conditions were the same as in Example 1, except that: one part of the precursor slurry was loaded into a spraying machine, sprayed at 85°C, and uniformly sprayed onto a ceramic ring carrier. It was then placed in a muffle furnace and calcined at 450°C for 15 hours, followed by natural cooling to obtain the catalyst. The XRD pattern of the catalyst showed only diffraction peaks of the TiO2 crystalline phase; other components were distributed as a monolayer on the TiO2 surface.

[0125] The catalyst particles are 25 mesh, and the method used is... A fixed-bed reactor with a length of 400 mm was used. The catalyst loading was 4 g. The reaction system was at atmospheric pressure and the reaction temperature was 365 °C. The molar ratio of the raw materials was 2-methylpyridine:NH3:air = 1:5:27. The catalyst weight loading (W2-picoline / Wcat) was 0.055 h⁻¹. -1 Evaluation after 2 hours showed that the yield of 2-cyanopyridine was 91.2%.

[0126] Example 14

[0127] All steps were the same as in Example 1. 15g of oxalic acid, 5g of vanadium pentoxide, 1.2g of phosphoric acid, 0.6g of potassium nitrate, 3g of ammonium molybdate, and 100g of titanium dioxide (90wt% anatase TiO2, the remainder being rutile) and 300mL of distilled water were weighed into a flask (temperature 85℃) to form a catalyst precursor slurry. Then, 0.5g of polyvinyl alcohol was dissolved in 10ml of water and added to the catalyst precursor slurry (solid content: 35%). The mixture was then heated and stirred continuously for 18h.

[0128] One part of the precursor slurry was loaded into a spraying machine and sprayed evenly onto a ceramic ring carrier at a spraying temperature of 120℃. The carrier was then placed in a muffle furnace and calcined at 450℃ for 15 hours. After natural cooling, the catalyst was obtained.

[0129] Under the same evaluation conditions as in Example 1, the evaluation results showed that the yield of 2-cyanopyridine was 89.8%.

[0130] Comparative Example 1

[0131] All conditions were the same as in Example 1, except that: one part of the precursor slurry was loaded into a spraying machine, sprayed at 120°C, and evenly sprayed onto a ceramic ring carrier. It was then placed in a muffle furnace and calcined at 450°C for 5 hours, followed by natural cooling to obtain the catalyst.

[0132] The catalyst particles are 25 mesh, and the method used is... A fixed-bed reactor with a length of 400 mm was used. The catalyst loading was 4 g. The reaction system was at atmospheric pressure and the reaction temperature was 365 °C. The molar ratio of the raw materials was 2-methylpyridine:NH3:air = 1:5:27. The catalyst weight loading (W2-picoline / Wcat) was 0.055 h⁻¹. -1 Evaluation after 2 hours showed that the yield of 2-cyanopyridine was 60.8%.

[0133] Figure 1 The XRD pattern of the catalyst prepared in Comparative Example 1 is shown. Figure 1 It can be seen that even if the ratio of active components is the same, but the calcination time is not within the range of this invention, the XRD pattern of the prepared catalyst will show crystalline phases other than TiO2.

[0134] The evaluation results show that the catalyst prepared by the method of the present invention has significantly better reaction performance when applied to the catalytic ammoxidation of 2-methylpyridine to 2-cyanopyridine.

[0135] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An ammonia oxidation catalyst, characterized in that, The catalyst comprises a support, an active component, and an auxiliary component. The active component comprises V and Ti. The auxiliary component comprises one or more of non-metallic elements, alkali metal elements, and Group VIB elements. The XRD pattern of the catalyst shows only diffraction peaks of the TiO2 crystalline phase, and the active component and auxiliary component are distributed on the TiO2 surface in a monolayer state. The molar ratio of vanadium to titanium is 1:24-32; The molar ratio of vanadium to the auxiliary component elements is 1:0.1-1.

5.

2. The catalyst according to claim 1, wherein, TiO2 crystal phases include rutile TiO2 and / or anatase TiO2; and / or The carrier is selected from at least one of alumina, silica, and ceramic rings; and / or The auxiliary component elements include at least two of the following: non-metallic elements, alkali metal elements, and group VIB elements.

3. The catalyst according to claim 2, wherein, Anatase TiO2 ≥ 90 wt%; and / or The auxiliary component elements include non-metallic elements, alkali metal elements and Group VIB elements. The nonmetallic element is selected from at least one of phosphorus, boron, selenium and arsenic; The alkali metal element is selected from at least one of lithium, sodium, potassium and rubidium; Group VIB elements are selected from at least one of chromium, molybdenum, and tungsten.

4. The catalyst according to claim 1 or 2, wherein, The molar ratio of vanadium to nonmetallic elements is 1:0.1-0.5; and / or The molar ratio of vanadium to alkali metals is 1:0.05-0.2; and / or The molar ratio of vanadium to group VIB elements is 1:0.15-0.5; and / or The preparation method of the ammonia oxidation catalyst includes: preparing a slurry to be sprayed from an active component source and an auxiliary component source, and preparing it by spraying. The solid content of the slurry to be sprayed is 25-40 wt%. The calcination time for the coating method is 10-18 hours.

5. The catalyst according to claim 4, wherein, The calcination time for the coating method is 14-16 hours; and / or The slurry to be sprayed contains a polymer binder; and / or The polymer binder is selected from at least one of polyvinyl alcohol, polyvinylpyrrolidone, and polyacrylamide.

6. The catalyst according to claim 5, wherein, The mass ratio of the polymer binder to vanadium is (0.05-0.2):1; and / or The polymer binder is selected from polyvinyl alcohol with a degree of polymerization between 25,000 and 150,000 molecular weights.

7. A method for preparing the ammonia oxidation catalyst according to any one of claims 1-6, characterized in that, The method includes: A vanadium source, titanium source, auxiliary component source, and optionally a polymer binder are prepared into a slurry to be sprayed. The slurry is then sprayed onto a carrier by a spraying method, followed by calcination for 10-18 hours.

8. The preparation method according to claim 7, wherein, The titanium source is titanium dioxide, of which anatase TiO2 ≥ 90 wt%; The mass ratio of the polymer binder to vanadium is (0.05-0.2):1; and / or The polymer binder is selected from at least one of polyvinyl alcohol, polyvinylpyrrolidone, and polyacrylamide; and / or The slurry to be sprayed contains organic acids; and / or The solid content of the slurry to be sprayed is 25-40 wt%; and / or the solvent in the slurry includes deionized water; and / or The roasting time is 14-16 hours; and / or the roasting temperature is 400-600℃; and / or The conditions for spraying include a temperature of 80-180℃.

9. The preparation method according to claim 8, wherein, The polymer binder is selected from polyvinyl alcohol with a degree of polymerization between 25,000 and 150,000 molecular weights; and / or The molar ratio of the organic acid to vanadium is (3-5):1; the organic acid is selected from at least one of citric acid, malic acid, and oxalic acid; and / or The roasting temperature is 450-550℃; and / or The conditions for spraying include a temperature of 100-160℃.

10. The preparation method according to claim 7 or 8, wherein, The method includes: (1) After the vanadium source and the organic acid are mixed in a solvent, a mixture A is formed; (2) Mix the mixture A with the auxiliary agent source for a second time to form the mixture B; (3) The titanium source is mixed with mixture B for the third time to form mixture C; (4) The polymer binder and the mixture C are mixed for the fourth time to form the mixture D as the slurry to be sprayed. The mixture D is sprayed onto the carrier and then calcined.

11. The preparation method according to claim 10, wherein, The conditions for the third and fourth mixtures each include: Temperature is 80-90 o C; and / or The fourth mixing time is 12h-24h; and / or The solvent is deionized water; and / or The conditions for the first mixture and the second mixture each include: The temperature is 70-85℃.

12. The preparation method according to claim 11, wherein, The fourth mixing time is 15-20 hours.

13. The use of the ammonia oxidation catalyst according to any one of claims 1-6 in the ammonia oxidation preparation of pyridine compounds.

14. A method for preparing 2-cyanopyridine, characterized in that, The method includes: contacting the raw material with a catalyst; The catalyst comprises the ammonia oxidation catalyst according to any one of claims 1-6.

15. The method according to claim 14, wherein, The contact takes place in a fixed-bed reactor; and / or The raw materials include 2-methylpyridine, ammonia, and air; and / or The contact conditions include: Temperature 280-400℃; and / or Time: 8-20 hours; and / or Pressure 101-120 kPa.

16. The method according to claim 15, wherein, The molar ratio of 2-methylpyridine, ammonia, and air is 1:(1-10):(1-40).

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