Ammonia oxidation catalyst as well as preparation method and application thereof

Abstract

The invention relates to an ammoxidation catalyst as well as a preparation method and application thereof, the ammoxidation catalyst belongs to a V-Cr system catalyst, the problem that the service life of the catalyst is shortened due to loss of active components is effectively solved, meanwhile, the applicable raw material proportion of the catalyst can be widened, and particularly, the catalyst still can keep relatively high activity under a low ammonia proportion.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, in particular to ammonia oxidation catalysts, and specifically relates to an ammonia oxidation catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Aromatic nitriles have high chemical activity. Through hydrogenation and condensation reactions, various fine chemical products can be synthesized, and they have been widely used in many industries such as pharmaceuticals, fragrances, pesticides, and resins. As an important raw material source, the demand for aromatic nitriles has shown an increasing trend at home and abroad in recent years. The synthesis principle is that aromatic nitriles are obtained by ammoxidation of aromatic hydrocarbons through oxidation under the conditions of ammonia and a catalyst. Since the above manufacturing process has the advantages of simple operation, safe operation, high yield, and low pollution, many scholars at home and abroad have invested a lot of research in this to achieve wide application.

[0003] In the 1950s of the 20th century, Allied Company took the lead in researching and developing the ammoxidation technology of aromatic hydrocarbons. At the same time, many companies, such as Distiller and Bayer, also started researching related ammonia oxidation catalysts. In 1969, Nippon Shokubai Kagaku Kogyo Co., Ltd. built a production device for phthalonitrile and benzonitrile by the ammoxidation of mixed aromatic hydrocarbons using its own developed technology. In 1970, a company in Japan and a US company jointly built a production device for isophthalonitrile. After that, Mitsubishi Gas Chemical of Japan successfully built an industrial production device for isophthalonitrile with the US Bagder Company, making the ammoxidation technology of aromatic hydrocarbons popularized and applied.

[0004] 201610634733.X relates to a wear-resistant ammonia oxidation catalyst with the general formula V 1.0 Cr a A b B c C d M e O x ; wherein A is selected from at least one of the elements P, B, Bi, Sb, and As; B is selected from at least one of the elements Mn, Ni, Co, Ti, Sn, Mo, or rare earth elements; C is selected from at least one of alkali metals or alkaline earth metals; M is selected from at least one of Zr and W; and by strictly controlling the addition order of each component, the wear resistance of the catalyst is effectively improved, and the problems of poor wear resistance, high loss, and poor catalyst activity of the existing catalyst are solved.

[0005] CN201210240053.1 relates to a method for preparing o-chlorobenzonitrile. By using a fluidized bed catalyst, the catalyst uses silica as a carrier, and the active component has a general formula of VP a Xb Y c Z d O m , wherein X is selected from at least one of oxides of B or As; Y is selected from at least one of alkali metal oxides or alkaline earth metal oxides; Z is selected from at least one of metal oxides of Ni, Co, Pb, Fe, Mo or W, which solves the problems of low yield of o-chlorobenzonitrile and small reaction load in the prior art.

[0006] CN106362760A discloses an ammoxidation mixed catalyst V 1.0 Cr a A b B c C d D e E f M g O x , wherein A is selected from at least one element in Group IIIA of the periodic table; B is selected from at least one element in Group VA of the periodic table; C is selected from at least one of alkali metals or alkaline earth metals; D is selected from at least one element in Group VIII of the periodic table; E is selected from at least one of Mo, Ti, Nb; M is selected from at least one of Zr, W. The method described in this patent effectively improves the abrasion resistance of the catalyst, while maintaining the high activity and selectivity of the catalyst. The obtained catalyst can be applied to the industrial production of aromatics ammoxidation.

[0007] In summary, the prior art has optimized the abrasion resistance and raw material cost of the ammoxidation catalyst, but has not mentioned measures to solve the problems of short catalyst life and large ammonia consumption caused by the loss of active components. The preparation method of this patent can realize the loading of some active components during the carrier forming process, making the catalyst have better shape selectivity for aromatic nitriles, improving the production efficiency of the catalyst, while reducing the ammonia consumption, reducing the loss rate of active components, improving the service life of the catalyst, and increasing the raw material conversion rate, reducing raw material waste, and having high mechanical strength, making the catalyst more suitable for large-scale industrial production applications, especially suitable for the application of m-xylene ammoxidation to prepare isophthalonitrile. Summary of the Invention

[0008] To solve the above technical problems, the present invention provides an ammonia oxidation catalyst, a preparation method thereof and an application thereof. The ammonia oxidation catalyst belongs to a V-Cr system catalyst, and can realize the inlay loading of some active components during the carrier forming process, so that the catalyst has better selectivity for aromatic nitriles, improves the production efficiency of the catalyst, and at the same time can reduce the consumption of ammonia gas, reduce the loss rate of active components, improve the service life of the catalyst, and can also improve the raw material conversion rate, reduce raw material waste, and has high mechanical strength, making the catalyst more suitable for large-scale industrial production applications, especially suitable for the application of ammoxidation of m-xylene to prepare isophthalonitrile.

[0009] One of the purposes of the present invention is to provide an ammonia oxidation catalyst. The ammonia oxidation catalyst includes a carrier and active components. The active components satisfy the following structural formula in terms of atomic ratio: V 1.0 Cr a B b C c D d O x ;

[0010] Among them, B is selected from any one or a combination of at least two of B, Ti or Al, C is selected from any one or a combination of at least two of Cu, Ni, Mo or Ag, and D is selected from any one or a combination of at least two of Fe, P or Sb;

[0011] In the present invention, a = 0.05 - 5, b = 0.005 - 2, c = 0.001 - 1, d = 0.001 - 1, x = 2.0 - 9.0, and x is a value determined by the oxidation degree of other elements, that is, x satisfies the balancing rule.

[0012] It should be noted that in the structural formula V 1.0 Cr a B b C c D d O xAmong them, a = 0.05 to 5, such as 0.05, 0.1, 0.3, 0.5, 0.7, 1, 1.5, 2, 3, 3.5, 4 or 5, etc., b = 0.01 to 2, such as 0.01, 0.03, 0.05, 0.08, 0.1, 0.3, 0.5, 0.7, 1, 1.3, 1.5, 1.7 or 2, etc., c = 0.001 to 1, such as 0.001, 0.003, 0.005, 0.008, 0.01, 0.03, 0.05, 0.08, 0.1, 0.3, 0.5 or 1, etc., d = 0.001 to 1, such as 0.001, 0.003, 0.005, 0.008, 0.01, 0.03, 0.05, 0.08, 0.1, 0.3, 0.5 or 1, etc., but not limited to the listed values, and other unlisted values within the above value ranges are equally applicable.

[0013] As a preferred technical solution of the present invention, in the structural formula V 1.0 Cr a B b C c D d O x Among them, a = 0.08 to 3, such as 0.08, 0.15, 0.35, 0.65, 0.85, 1.2, 1.8, 2.3, 2.5, 2.8 or 3, etc., b = 0.05 to 1, such as 0.05, 0.07, 0.11, 0.15, 0.25, 0.45, 0.65, 0.85, 0.9 or 1, etc., c = 0.05 to 0.8, such as 0.05, 0.06, 0.07, 0.09, 0.12, 0.2, 0.4, 0.6 or 0.8, etc., d = 0.01 to 0.5, such as 0.01, 0.02, 0.04, 0.06, 0.09, 0.12, 0.15, 0.23, 0.35, 0.45 or 0.5, etc., but not limited to the listed values, and other unlisted values within the above value ranges are equally applicable.

[0014] As a preferred technical solution of the present invention, based on the total mass of the ammoxidation catalyst, the mass percentage content of the active component is 20 to 70%, such as 20%, 30%, 40%, 50%, 60% or 70%, etc., but not limited to the listed values, and other unlisted values within the above value ranges are equally applicable; the balance is the carrier.

[0015] Preferably, the carrier is silica.

[0016] Preferably, the silicon / B element ratio of the carrier is 1:(0.001-0.1), such as 1:0.001, 1:0.005, 1:0.01, 1:0.03, 1:0.05, 1:0.07 or 1:0.1, etc., preferably 1:(0.005-0.07), such as 1:0.005, 1:0.007, 1:0.009, 1:0.02, 1:0.04, 1:0.06 or 1:0.07, etc., but not limited to the listed values, and other unlisted values within the above numerical range are equally applicable.

[0017] The second object of the present invention is to provide a method for preparing the ammoxidation catalyst, and the preparation method includes the following steps:

[0018] (1) Weigh a quantitative silicon source according to the amount of SiO2 of the carrier required in the ammoxidation catalyst, mix the raw material containing B element with oxalic acid or tartaric acid aqueous solution to form a mixed reaction solution A, and add the mixed reaction solution A to the silicon source to form a mixed slurry B;

[0019] (2) Stir the mixed slurry B at a constant temperature to obtain a slurry C;

[0020] (3) According to the structural formula of the active component in the ammoxidation catalyst, configure an aqueous solution of compounds containing V, Cr, C element, and D element to form a reaction solution D;

[0021] (4) Slowly mix the slurry C in step (2) with the reaction solution D in step (3) to form an impregnation mixed solution E;

[0022] (5) Subject the impregnation mixed solution E in step (4) to aging, concentration, drying and calcination in sequence to obtain the ammoxidation catalyst.

[0023] The B element added in step (1) also serves as an active component of the catalyst;

[0024] In step (1), the silicon source is selected from tetraethyl orthosilicate, water glass and / or silica sol; preferably, the silicon / B element ratio in the silicon source is 1:(0.001-0.1), preferably 1:(0.005-0.07); it should be noted that by precisely adjusting the silicon / B element ratio to 1:(0.001-0.1), the acid amount of the carrier can be precisely controlled, providing more ammonia adsorption sites for the subsequent ammoxidation reaction. If the silicon / B element is higher than the selected range of this patent, it will lead to insufficient acid sites and insufficient ammonia adsorption capacity, resulting in a decrease in the conversion rate of m-xylene and insufficient activity; if the silicon / B element ratio is lower than the selected range of this patent, the number of strong acid sites will increase, resulting in excessive ammonia adsorption and difficulty in carrying out the ammoxidation reaction with xylene, leading to a deeper degree of deep oxidation of xylene to generate carbon dioxide.

[0025] In the step (1), the raw material containing element B is selected from one or more of boric acid, boron oxide, basic copper carbonate, copper chloride, and titanium hydroxy dilactate; preferably, the element B includes boric acid, boron oxide, basic copper carbonate, and titanium hydroxy dilactate, and more preferably boric acid and boron oxide.

[0026] In the step (1), the mass concentration of the oxalic acid or tartaric acid aqueous solution is 1% - 60%, such as 10%, 20%, 30%, 40%, 50%, and preferably, the mass concentration of the oxalic acid or tartaric acid aqueous solution is 30%, 40%, 50%, 60%.

[0027] In the step (2), the stirring temperature is 55 - 100 °C, and the stirring time is 3 - 48 h.

[0028] It should be noted that the carrier SiO2 is modified and loaded with oxalic acid and element B, so that a special bond combination is formed between element B and Si and O, making the loading of element B on the catalyst more stable and not lost due to the increase in the running time. Since element B has a certain inhibitory effect on the active sites of the catalyst, if its content is too high, the catalyst activity is too poor; if the content is too low, the catalyst activity is too high, the deep oxidation degree of m-xylene is obvious, and the small molecule products increase significantly, affecting the product yield.

[0029] It should be noted that oxalic acid or tartaric acid is also an oxidant for reducing the valence states of active components V and Cr, which is more conducive to the formation of the active ingredient CrVO4.

[0030] As a preferred technical solution of the present invention, in the step (3), the compounds containing elements V, Cr, C, and D are selected from vanadium pentoxide, chromium trioxide, copper nitrate, copper acetate, nickel nitrate, ammonium molybdate, molybdenum oxide, silver nitrate, etc.

[0031] As a preferred technical solution of the present invention, in the step (5), the aging temperature is 50 - 120 °C, such as 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, or 100 °C, etc., and the pressure is 10 kPa - 0.5 Mpa, such as 10 kPa, 50 kPa, 100 kPa, 0.5 Mpa, etc., but it is not limited to the listed values, and other unlisted values within the above value range are equally applicable.

[0032] As a preferred technical solution of the present invention, the concentration in step (5) is evaporation concentration, and the temperature of the evaporation concentration is 50-120°C, such as 50°C, 60°C, 70°C, 80°C, 90°C or 100°C, etc., but is not limited to the listed values, and other unlisted values within the above numerical range are equally applicable. After evaporation concentration, a slurry feed liquid with a solid content of 30-70% is obtained. The solid content can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, etc., but is not limited to the listed values, and other unlisted values within the above numerical range are equally applicable.

[0033] As a preferred technical solution of the present invention, the drying in step (5) is spray drying. Preferably, the inlet temperature of the spray drying is 150-350°C, such as 150°C, 160°C, 180°C, 170°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 280°C, 290°C or 350°C, etc., and the outlet temperature is 90-190°C, such as 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C or 180°C, etc., but is not limited to the listed values, and other unlisted values within the above numerical range are equally applicable.

[0034] As a preferred technical solution of the present invention, the heating rate of the roasting in step (5) is 1-10°C / min, such as 1°C / min, 3°C / min, 5°C / min, 7°C / min or 10°C / min, etc., preferably 2-6°C / min, such as 2°C / min, 2.5°C / min, 3.5°C / min, 4.5°C / min, 5.5°C / min or 6°C / min, etc., but is not limited to the listed values, and other unlisted values within the above numerical range are equally applicable.

[0035] Preferably, the temperature of the roasting is 500°C-700°C, such as 500°C, 600°C, 620°C, 650°C, 680°C, 700°C, 720°C or 750°C, etc., preferably 620-700°C, such as 620°C, 640°C, 660°C, 670°C or 700°C, etc., but is not limited to the listed values, and other unlisted values within the above numerical range are equally applicable.

[0036] Preferably, the time of the roasting is 1-10h, such as 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h or 9h, etc., but is not limited to the listed values, and other unlisted values within the above numerical range are equally applicable.

[0037] The third object of the present invention is to provide a method for preparing isophthalonitrile, and the method includes the following contents:

[0038] m - Xylene, ammonia, and air are subjected to an ammoxidation reaction under the action of the above-mentioned ammoxidation catalyst to obtain isophthalonitrile.

[0039] The molar ratio of the reaction raw materials m - xylene:ammonia:air is 1:(0.5 - 10):(15 - 50), and the mass space velocity is 0.0005 - 0.05 h -1 , the reaction temperature is 300 - 500 °C, and the reaction pressure is 5 - 100 kPa;

[0040] Preferably, the raw material ratio of m - xylene:ammonia:air is 1:(1 - 7):(25 - 35);

[0041] Preferably, the mass space velocity is 0.001 - 0.01 h-1;

[0042] Preferably, the reaction temperature is 350 - 450 °C;

[0043] Preferably, the reaction pressure is 8 - 70 kPa;

[0044] Compared with the prior art, the present invention has at least the following beneficial effects:

[0045] (1) The ammoxidation catalyst described in the present invention belongs to the V - Cr system catalyst. By precisely defining the stoichiometric ratio of V to Cr in the active component as 1.0:(0.05 - 5) and the ratio of class B / silica, the stoichiometric ratios of class C and class D metal elements, not only does the catalyst have better selectivity for aromatic nitriles, improving the production efficiency of the catalyst, but also it can reduce the consumption of ammonia, reduce the loss rate of the active component, extend the service life of the catalyst, reduce the degree of deep oxidation of the raw materials, increase the conversion rate of the raw materials, reduce raw material waste, and has high mechanical strength, making the catalyst more suitable for large - scale industrial production applications, especially suitable for the application of ammoxidation of m - xylene to prepare isophthalonitrile.

[0046] (2) The carrier SiO2 is loaded with oxalic acid and class B elements, so that special bond combinations are formed between class B elements and Si and O, making the loading of class B elements on the catalyst more stable and not liable to be lost due to the increase in operation time. Since class B elements have a certain inhibitory effect on the active sites of the catalyst, if their content is too high, the catalyst activity is too poor; if the content is too low, the catalyst activity is too high, the degree of deep oxidation of m - xylene is obvious, and small - molecule products increase significantly, affecting the product yield. Moreover, for the catalyst prepared by the preparation method mentioned in this patent, its ammonia conversion rate is low, the degree of deep oxidation is low, the product yield is high, the generated water is greatly reduced, and the loss of class B elements (especially boron elements) can also be reduced, greatly extending the service life of the catalyst.

[0047] (3) By precisely limiting the stoichiometric ratio of Cr to V in the active component to a=0.05-5, and limiting the stoichiometric ratio of C and D metal elements, an effective composite reaction active site can be formed, which enables the active component and the carrier to form a synergistic reaction active site, effectively reducing the activation energy of the ammonia oxidation reaction, increasing the adsorption amount of ammonia, reducing the deep oxidation degree of raw materials such as m-xylene, reducing the generation of small molecular products, and ensuring the conversion rate and product selectivity of raw materials such as m-xylene. It can effectively ensure the stability and mechanical strength of the ammonia oxidation catalyst and ensure the stability of the ammonia oxidation catalyst during long-term operation.

[0048] (4) The ammonia oxidation catalyst described in this patent can effectively reduce the consumption of ammonia and air. At a relatively low (air, ammonia) / meta-xylene raw material ratio, the meta-xylene conversion rate and dinitrile yield are maintained at a high level, effectively reducing the cost of raw material and ammonia recovery processing. DETAILED DESCRIPTION

[0049] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0050] The raw materials used in the examples are all conventional raw materials in the art, and the reagents used in the experiments are Aladdin brand reagents, and the purity specification used is AR grade

[0051] The calculation formulas for the conversion of raw material meta-xylene and the selectivity of target product isophthalonitrile in the embodiment are as follows:

[0052] Meta-xylene conversion rate (%) = (the number of moles of meta-xylene reacted / the number of moles of meta-xylene fed) × 100%;

[0053] Isophthalonitrile selectivity (%) = (the number of moles of isophthalonitrile produced / the number of moles of meta-xylene reacted) × 100%.

[0054] Ammonia conversion rate (%) = (moles of reacted ammonia / moles of feed ammonia) × 100%;

[0055] Example 1

[0056] This embodiment provides an ammonia oxidation catalyst and a preparation method and application thereof, wherein the preparation method comprises the following steps:

[0057] (1) Weigh 300 g of oxalic acid into a measuring cup, add 18.22 g of boric acid, and completely dissolve in 300 g of 90°C hot water;

[0058] (2) Weigh 303.08 g of 30 wt% silica sol into a three-necked flask, and add the mixed solution of boric acid and oxalic acid to the silica sol at a rate of 10 g / min with a stirring speed of 180 r / min. After the feeding is completed, age at 85 °C for 12 h.

[0059] (3) Weigh 53.34 g of chromium trioxide and 44.9 g of vanadium pentoxide, dissolve them with 100 g of deionized water at room temperature, add them to the solution in step (2) after aging, with a dropping rate of 10 g / min and a stirring speed of 280 r / min. After the dropping is completed, stir at 85 °C for 2 h.

[0060] (4) Weigh 6.2 g of copper nitrate, 41 g of ammonium heptamolybdate, and 2.85 g of 85% phosphoric acid, dissolve them with 10 g, 50 g, and 10 g of water respectively, and add them to the aging solution obtained in step (3) to form an impregnation solution.

[0061] (5) The impregnation solution is evaporated and concentrated at 85 °C and 50 kPa to obtain a slurry with a solid content of 40%, which is spray-dried. The inlet temperature of the spray dryer is 250 °C and the outlet temperature is 105 °C to obtain the catalyst precursor powder, which is then calcined at 600 °C for 5 h with a heating rate of 2 °C / min to obtain Catalyst 1#.

[0062] As detected by ICP, the proportion of active components in the above ammoxidation catalyst 1# is V 1.0 Cr 1.0 B 0.59 Mo 0.5 P 0.05 Cu 0. 1O 6.61 。

[0063] Load the above-obtained ammoxidation catalyst 1# into a laboratory ammoxidation fluidized bed reactor for reaction performance evaluation. The feed ratio of the reaction raw materials is in a molar ratio of m-xylene: ammonia: air of 1:3:30. The reaction temperature of the ammoxidation reactor is 400 °C, the reaction pressure (gauge pressure) is 70 kPa, and the catalyst weight load in the reactor is 0.05 h -1 。

[0064] After the reactor runs for 100 h, the conversion rate of m-xylene is 99.5% and the selectivity of isophthalonitrile is 85.7%.

[0065] Example 2

[0066] This example provides an ammoxidation catalyst, its preparation method and application. The preparation method includes the following steps:

[0067] (1) Weigh 300 g of oxalic acid into a measuring cup and completely dissolve it with 300 g of hot water at 90 °C;

[0068] (2) Weigh 303.08 g of 30 wt% silica sol into a three-necked flask, add the oxalic acid solution to the silica sol at a rate of 10 g / min, and stir at a speed of 180 r / min. After the feeding is completed, age at 85 °C for 12 h.

[0069] (3) Weigh 53.34 g of chromium trioxide and 44.9 g of vanadium pentoxide, dissolve them with 100 g of deionized water at room temperature, add them to the solution in step (2) after aging, add dropwise at a rate of 10 g / min, and stir at a rotation speed of 280 r / min. After the dropwise addition is completed, stir at 85 °C for 2 h.

[0070] (4) Weigh 6.2 g of copper nitrate, 4.1 g of ammonium heptamolybdate, and 2.85 g of 85% phosphoric acid, dissolve them with 10 g, 50 g,

[0071] 10 g of water respectively, and add them to the aged solution obtained in step (3) to form an impregnation solution.

[0072] (5) The impregnation solution is evaporated and concentrated at 85 °C and 50 kPa to obtain a slurry with a solid content of 40%, and then spray-dried. The inlet temperature of the spray dryer is 250 °C and the outlet temperature is 105 °C to obtain the catalyst precursor powder, and then calcined at 600 °C for 5 h with a heating rate of 2 °C / min to obtain catalyst 2#.

[0073] After testing, the proportion of active components in the above ammonia oxidation catalyst 2# is V 1.0 Cr 1.0 Mo 0.05 P 0.05 Cu 0.1 O 4.375 .

[0074] Load the obtained ammonia oxidation catalyst 2# into a laboratory ammonia oxidation fluidized bed reactor for reaction performance evaluation. The feed ratio of the reaction raw materials is in the molar ratio of m-xylene: ammonia: air of 1:3:30. The reaction temperature of the ammonia oxidation reactor is 400 °C, the reaction pressure (gauge pressure) is 70 kPa, and the catalyst weight load in the reactor is 0.05 h -1 .

[0075] After the reactor runs for 100 h, the conversion rate of m-xylene is 99.8%, and the selectivity of isophthalonitrile is 49.7%.

[0076] Example 3

[0077] This example provides an ammonia oxidation catalyst, its preparation method and application. The preparation method includes the following steps:

[0078] (1) Weigh 300 g of oxalic acid into a measuring cup, completely dissolve it with 300 g of 90 °C hot water, and add 30.5 g of boric acid;

[0079] (2) Weigh 303.08 g of 30 wt% silica sol into a three-necked flask, add the oxalic acid solution to the silica sol at a rate of 10 g / min, and stir at a speed of 180 r / min. After the feeding is completed, age at 85 °C for 12 h.

[0080] (3) Weigh 53.34 g of chromium trioxide and 44.9 g of vanadium pentoxide, dissolve them in 100 g of deionized water at room temperature, add them to the solution obtained in step (2) after aging, add dropwise at a rate of 10 g / min, and stir at a rotation speed of 280 r / min. After the dropwise addition is completed, stir at 85 °C for 2 h.

[0081] (4) Weigh 6.2 g of copper nitrate, 21.3 g of ammonium heptamolybdate, and 2.85 g of 85% phosphoric acid, dissolve them in 10 g,

[0082] 50 g, and 10 g of water respectively, and add them to the aged solution obtained in step (3) to form an impregnation solution.

[0083] (5) The impregnation solution is evaporated and concentrated at 85 °C and 50 kPa to obtain a slurry with a solid content of 40%, and then spray-dried. The inlet temperature of the spray dryer is 250 °C, and the outlet temperature is 105 °C to obtain the catalyst precursor powder. Then, it is calcined at 600 °C for 5 h with a heating rate of 2 °C / min to obtain catalyst 3#.

[0084] After testing, the proportion of the active components in the above ammonia oxidation catalyst 3# is V 1.0 Cr 1.0 B 1.0 Mo 0.005 P 0.05 Cu 0.1 O 5.74 .

[0085] Load the above-obtained ammonia oxidation catalyst 3# into a laboratory ammonia oxidation fluidized bed reactor for reaction performance evaluation. The feed ratio of the reaction raw materials is based on the molar ratio of m-xylene: ammonia: air of 1:3:30. The reaction temperature of the ammonia oxidation reactor is 400 °C, the reaction pressure (gauge pressure) is 70 kPa, and the catalyst weight load in the reactor is 0.05 h -1 .

[0086] After the reactor operates for 100 h, the conversion rate of m-xylene is 98.1%, and the selectivity of isophthalonitrile is 83%.

[0087] Example 4

[0088] This example provides an ammonia oxidation catalyst, its preparation method and application. The preparation method includes the following steps:

[0089] (1) Weigh 300 g of oxalic acid into a measuring cup, completely dissolve it with 300 g of hot water at 90 °C, and add 30.5 g of boric acid;

[0090] (2) Weigh 303.08 g of 30 wt% silica sol into a three-necked flask, add the oxalic acid solution to the silica sol at a rate of 10 g / min, and the stirring speed is 180 r / min. After the feeding is completed, age at 85 °C for 12 h.

[0091] (3) Weigh 53.34 g of chromium trioxide and 44.9 g of vanadium pentoxide, dissolve them with 100 g of deionized water at room temperature, add them to the solution in step (2) after aging is completed, the dropping rate is 10 g / min, and the stirring speed is 280 r / min. After the dropping is completed, stir at 85 °C for 2 h.

[0092] (4) Weigh 4.6 g of copper nitrate, 65.6 g of ammonium heptamolybdate, and 0.56 g of 85% phosphoric acid, and dissolve them with 10 g,

[0093] 150 g, and 10 g of water respectively, and add them to the aged solution obtained in step (3) to form an impregnation solution.

[0094] (5) The impregnation solution is evaporated and concentrated at 85 °C and 50 kPa to obtain a slurry with a solid content of 40%, and then spray-dried. The inlet temperature of the spray dryer is 250 °C, and the outlet temperature is 105 °C to obtain the catalyst precursor powder. Then, it is calcined at 600 °C for 5 h with a heating rate of 2 °C / min to obtain catalyst 4#.

[0095] After testing, the proportion of active components in the above ammonia oxidation catalyst 4# is V 1.0 Cr 1.0 B 1.0 Mo 0.8 P 0.01 Cu 0.05 O 7.975 .

[0096] Load the above-obtained ammonia oxidation catalyst 4# into a laboratory ammonia oxidation fluidized bed reactor for reaction performance evaluation. The feed ratio of the reaction raw materials is based on the molar ratio of m-xylene: ammonia: air of 1:3:30. The reaction temperature of the ammonia oxidation reactor is 400 °C, the reaction pressure (gauge pressure) is 70 kPa, and the catalyst weight load in the reactor is 0.05 h -1 .

[0097] After the reactor runs for 100 h, the conversion rate of m-xylene is 97.1%, and the selectivity of isophthalonitrile is 79%.

[0098] Example 5

[0099] This example provides an ammonia oxidation catalyst, its preparation method and application, and the preparation method includes the following steps:

[0100] (1) Weigh 300 g of oxalic acid into a measuring cup, completely dissolve it with 300 g of hot water at 90 °C, and add 1.52 g of boric acid.

[0101] (2) Weigh 303.08 g of 30 wt% silica sol into a three-necked flask, add the oxalic acid solution to the silica sol at a rate of 10 g / min, and the stirring speed is 180 r / min. After the addition is completed, age at 85 °C for 12 h.

[0102] (3) Weigh 53.34 g of chromium trioxide and 44.9 g of vanadium pentoxide, dissolve them with 100 g of deionized water at room temperature, add them to the solution obtained in step (2) after aging, the dropping rate is 10 g / min, the stirring speed is 280 r / min, and after the dropping is completed, stir at 85 °C for 2 h.

[0103] (4) Weigh 74 g of copper nitrate, 29.5 g of antimony acetate, and 28.4 g of 85% phosphoric acid, dissolve them with 10 g, 150 g,

[0104] 10 g of water respectively, and add them to the aging solution obtained in step (3) to form an impregnation solution.

[0105] (5) The impregnation solution is evaporated and concentrated at 85 °C and 50 kPa to obtain a slurry with a solid content of 40%, and then spray-dried. The inlet temperature of the spray dryer is 250 °C, and the outlet temperature is 105 °C to obtain the catalyst precursor powder, and then calcined at 600 °C / 5 h with a heating rate of 2 °C / min to obtain catalyst 5#.

[0106] After detection, the proportion of active components in the above-mentioned ammoxidation catalyst 5# is V 1.0 Cr 1.0 B 0.05 Sb 0.2 P 0.5 Cu 0.8 O 6.425 .

[0107] Load the above-mentioned obtained ammoxidation catalyst 5# into a laboratory ammoxidation fluidized bed reactor for reaction performance evaluation. The reaction raw material feed ratio is in the molar ratio of m-xylene: ammonia: air of 1:3:30. The reaction temperature of the ammoxidation reactor is 400 °C, the reaction pressure (gauge pressure) is 70 kPa, and the catalyst weight load in the reactor is 0.05 h -1 .

[0108] After the reactor runs for 100 h, the conversion rate of m-xylene is 98.5%, and the selectivity of isophthalonitrile is 80.1%.

[0109] Example 6#

[0110] The obtained ammoxidation catalyst 1# was charged into a laboratory ammoxidation fluidized bed reactor for reaction performance evaluation. The feed ratio of the reaction raw materials was in a molar ratio of m-xylene: ammonia: air of 1:3:30. The reaction temperature of the ammoxidation reactor was 400 °C, the reaction pressure (gauge pressure) was 70 kPa, and the catalyst weight load in the reactor was 0.05 h -1 .

[0111] After the reactor ran for 500 h, the conversion rate of m-xylene was 99.4%, and the selectivity of isophthalonitrile was 86.1%.

[0112] Example 7#

[0113] The obtained ammoxidation catalyst 1# was charged into a laboratory ammoxidation fluidized bed reactor for reaction performance evaluation. The feed ratio of the reaction raw materials was in a molar ratio of m-xylene: ammonia: air of 1:1:30. The reaction temperature of the ammoxidation reactor was 400 °C, the reaction pressure (gauge pressure) was 70 kPa, and the catalyst weight load in the reactor was 0.05 h -1 .

[0114] After the reactor ran for 100 h, the conversion rate of m-xylene was 99.4%, and the selectivity of isophthalonitrile was 84.3%.

[0115] Comparative Example 1#

[0116] This comparative example provided an ammoxidation catalyst, its preparation method and application. The preparation method included the following steps:

[0117] (1) Take 300 g of oxalic acid in a measuring cup and completely dissolve it with 300 g of hot water at 90 °C.

[0118] (2) Weigh 53.34 g of chromium trioxide and 44.9 g of vanadium pentoxide, dissolve them with 100 g of deionized water at room temperature, add them to the solution in step (1) after aging, with a dropping rate of 10 g / min and a stirring speed of 280 r / min. After dropping, stir at 85 °C for 2 h.

[0119] (3) Weigh 18.22 g of boric acid, 6.2 g of copper nitrate, 21.3 g of ammonium heptamolybdate, and 2.85 g of 85% phosphoric acid, dissolve them with 200 g, 10 g, 50 g, and 10 g of water respectively, and add them to the aging solution obtained in step (2) to form an impregnation solution.

[0120] (4) The impregnation solution was evaporated and concentrated at 85 °C and 50 kPa to obtain a slurry with a solid content of 40%, and then spray-dried. The inlet temperature of the spray dryer was 250 °C and the outlet temperature was 105 °C to obtain the catalyst precursor powder, which was then calcined at 600 °C for 5 h with a heating rate of 2 °C / min to obtain the catalyst

[0121] After detection, the proportion of the active components in the above comparative catalyst 1# is V 1.0 Cr 1.0 B 0.59 Mo 0.005 P 0.05 Cu 0.1 O 4.31 。

[0122] The above-obtained comparative catalyst 1# was loaded into a laboratory ammonia oxidation fluidized bed reactor for reaction performance evaluation. The feed ratio of the reaction raw materials was in a molar ratio of m-xylene: ammonia: air of 1:3:30. The reaction temperature of the ammonia oxidation reactor was 400 °C, the reaction pressure (gauge pressure) was 70 kPa, and the catalyst weight load in the reactor was 0.05 h -1 。

[0123] After the reactor ran for 100 h, the conversion rate of m-xylene was 99.4%, and the selectivity of isophthalonitrile was 83.9%.

[0124] Comparative Example 2#

[0125] The above-obtained comparative agent 1# was loaded into a laboratory ammonia oxidation fluidized bed reactor for reaction performance evaluation. The feed ratio of the reaction raw materials was in a molar ratio of m-xylene: ammonia: air of 1:1:30. The reaction temperature of the ammonia oxidation reactor was 400 °C, the reaction pressure (gauge pressure) was 70 kPa, and the catalyst weight load in the reactor was 0.05 h -1 。

[0126] After the reactor ran for 100 h, the conversion rate of m-xylene was 98.3%, and the selectivity of isophthalonitrile was 80.7%.

[0127] Comparative Example 3#

[0128] The above-obtained comparative agent 1# was loaded into a laboratory ammonia oxidation fluidized bed reactor for reaction performance evaluation. The feed ratio of the reaction raw materials was in a molar ratio of m-xylene: ammonia: air of 1:3:30. The reaction temperature of the ammonia oxidation reactor was 400 °C, the reaction pressure (gauge pressure) was 70 kPa, and the catalyst weight load in the reactor was 0.05 h -1 。

[0129] After the reactor ran for 500 h, the conversion rate of m-xylene was 99.7%, and the selectivity of isophthalonitrile was 61.2%.

[0130] Table 1

[0131]

[0132]

[0133] In summary, the ammonia oxidation catalyst of the present invention belongs to the V-Cr system catalyst. Through the improvement of the preparation method, the carrier modification and impregnation can be carried out simultaneously, and part of the active components can be embedded and loaded, so that the catalyst has better selectivity for aromatic nitriles, improves the production efficiency of the catalyst, and at the same time can reduce the consumption of ammonia, reduce the loss rate of active components, and improve the service life of the catalyst. In addition, it can improve the raw material conversion rate, reduce raw material waste, and has high mechanical strength, making the catalyst more suitable for large-scale industrial production applications, especially suitable for the application of ammoxidation of m-xylene to prepare isophthalonitrile.

[0134] The applicant declares that the present invention uses the above embodiments to illustrate the detailed process equipment and process flow of the present invention, but the present invention is not limited to the above detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent substitution of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and public scope of the present invention.

Claims

1. An ammonia oxidation catalyst, the ammonia oxidation catalyst comprising a carrier and an active component, the active component satisfying the following structural formula in terms of atomic ratio: V 1.0 Cr a B b C c D d O x ; Among them, B is selected from any one or a combination of at least two of B, Ti or Al, C is selected from any one or a combination of at least two of Cu, Ni, Mo or Ag, and D is selected from any one or a combination of at least two of Fe, P or Sb; a = 0.05 - 5, b = 0.005 - 2, c = 0.001 - 1, d = 0.001 - 1, x = 2.0 - 9.

0.

2. The ammonia oxidation catalyst according to claim 1, characterized in that, Based on the total mass of the ammoxidation catalyst, the mass percentage content of the active component is 20 - 70%; and / or, the carrier is silica.

3. The method for preparing the ammoxidation catalyst according to claim 1 or 2, wherein the preparation method comprises the following steps: (1) Weigh a quantitative silicon source according to the amount of the carrier SiO2 required in the ammoxidation catalyst. Mix the raw material containing element B with an aqueous solution of oxalic acid or tartaric acid to form a mixed reaction solution A, and add the mixed reaction solution A to the silicon source to form a mixed slurry B; (2) Stir the mixed slurry B at a constant temperature to obtain a slurry C; (3) According to the structural formula of the active component in the ammoxidation catalyst, configure an aqueous solution of compounds containing elements V, Cr, C, and D to form a reaction solution D; (4) Slowly mix the slurry C in step (2) with the reaction solution D in step (3) to form an impregnation mixed solution E; (5) Subject the impregnation mixed solution E in step (4) to aging, concentration, drying and calcination in sequence to obtain the ammoxidation catalyst.

4. The preparation method according to claim 3, characterized in that, In step (1), the silicon source is selected from tetraethyl orthosilicate, water glass and / or silica sol; preferably, the ratio of silicon to element B in the silicon source is 1:(0.001 - 0.1), preferably 1:(0.005 - 0.07).

5. The preparation method according to claim 3 or 4, characterized in that, In step (1), the raw material containing element B is selected from one or more of boric acid, boron oxide, basic copper carbonate, copper chloride, titanium hydroxy dilactate; preferably, element B includes boric acid, boron oxide, basic copper carbonate, titanium hydroxy dilactate, more preferably boric acid and boron oxide; and / or, the mass concentration of the aqueous solution of oxalic acid or tartaric acid is 1% - 60%.

6. The preparation method according to any one of claims 3-5, characterized in that, In step (3), the compounds containing V, Cr, C, and D are selected from vanadium pentoxide, chromium trioxide, copper nitrate, copper acetate, nickel nitrate, ammonium molybdate, molybdenum oxide, silver nitrate; and / or, in step (5), the aging temperature is 50 - 120 °C and the pressure is 10 kPa - 0.5 Mpa.

7. The preparation method according to any one of claims 3-6, characterized in that, The heating rate of the calcination in step (5) is 1 - 10 °C / min; the calcination temperature is 500 °C - 700 °C; the calcination time is 1 - 10 h.

8. A method for preparing isophthalonitrile, the method comprising the following steps: Perform an ammoxidation reaction on m - xylene, ammonia and air under the action of an ammoxidation catalyst to obtain isophthalonitrile, and the ammoxidation catalyst is selected from the ammoxidation catalyst according to claim 1 or 2 or the ammoxidation catalyst prepared by any method of claims 3 - 7.

9. The method according to claim 8, wherein The reaction raw material m - xylene: The molar ratio of ammonia to air is 1:(0.5 - 10):(15 - 50), the mass space velocity is 0.0005 - 0.05 h -1 , the reaction temperature is 300 - 500 °C, and the reaction pressure is 5 - 100 kPa.

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