Hydrocyanic acid catalyst for fluidized bed hydrogenation, and preparation method and application thereof

Abstract

The application provides a hydrogen cyanide catalyst for fluidized bed preparation, a preparation method and application. The catalyst is a supported catalyst, the weight of the carrier is 10-90% of the weight of the catalyst, the carrier is silica sol or alumina, the active component has a general formula of Mo6Bi a Fe b Ni c X d Y e K f Z g O n ; X is at least one of Mn, Te or Ta; Y is at least one of Mg, Ca, K or Na; K is at least one of Ce, Pr or Nd; Z is at least one of V, Cr or Zr; the application introduces multiple metals, wherein the X and Z metals can produce a mutual synergistic effect, promote the conversion of methanol, the K metal improves the selectivity and space-time yield of hydrogen cyanide, and the Y metal is an active site isolation metal and can appropriately isolate the active site, greatly reducing the yield of by-products carbon monoxide and carbon dioxide.

Description

Technical Field

[0001] This invention relates to the field of hydrogen cyanide catalyst technology, specifically to a catalyst for fluidized bed hydrogen cyanide production, its preparation method, and its application. Background Technology

[0002] Hydrogen cyanide is an important chemical, widely used in the synthesis of fine chemical intermediates due to its reactive properties, and has important applications in pharmaceuticals, metallurgy, electroplating, pesticides, and dyes. The production methods of hydrogen cyanide are mainly divided into two categories: direct synthesis and acrylonitrile by-product methods. Direct synthesis methods are further divided into four types: the Angle process, the BMA process, the light oil cracking process, and the methanol ammoxidation process. Among these, the Angle process, the BMA process, and the light oil cracking process use natural gas or light oil as raw materials and require high temperatures. The acrylonitrile by-product method involves the ammoxidation of propylene with propylene to produce acrylonitrile, yielding HCN as a by-product. With continuous advancements in propylene ammoxidation technology, the amount of hydrogen cyanide as a by-product has gradually decreased. The methanol ammoxidation process, originating from coal chemical processes, is more in line with China's energy structure, offering advantages such as inexpensive and readily available raw materials, low reaction temperatures, and high yields, thus possessing broad development prospects.

[0003] Currently, foreign patent reports on methanol ammoxidation to hydrogen cyanide catalysts are mainly classified into four categories: Mo-based, Sb-based, Mn-based, and BP oxide. The Changchun Institute of Applied Chemistry in my country also began research on Mo-Fe two-metal oxide catalysts for methanol ammoxidation to hydrogen cyanide in the late 1980s. Current catalyst development mainly focuses on Fe-Mo oxide catalysts, Mn-P oxide catalysts, PV oxide catalysts, and Pt-Rh alloy catalysts. Chinese patents CN101715369A, CN105905924A, and CN105905924A summarize in detail the characteristics of methanol ammoxidation reaction on composite oxide catalysts. Experimental data show that most catalysts have high hydrogen cyanide yields; however, from an industrial perspective, space-time yield is also a very important process indicator. Taking CN101715369A as an example, its optimal space-time yield is calculated to be 0.13 g(HCN) / (gcat). h) has a low space-time yield, therefore it is essential to develop catalysts with higher space-time yields of hydrogen cyanide.

[0004] At present, 10,000-ton-scale plants for preparing hydrocyanic acid through ammoxidation of methanol have been established in some regions in China, all of which adopt tubular fixed-bed reactors. In the actual use process, the catalyst has obvious hot spots and a large temperature distribution, which makes the active component Mo easily sublime and lose, resulting in the attenuation of catalyst service life. Therefore, it is necessary to regularly shut down the plant to replace the catalyst. In addition, affected by temperature distribution, the yield of hydrocyanic acid fluctuates greatly, and the content of by-product carbon dioxide is high. If a fluidized bed reaction process in which the catalyst is in a fluidized state is adopted, the problem of hot spots in the catalyst can be solved, the reaction temperature can be more uniform, the sublimation and loss of Mo component can be reduced, the service life of the catalyst can be improved, the fluctuation of yield can be reduced, the content of by-product carbon dioxide can be lowered. Meanwhile, the catalyst can be replenished online, which prolongs the operation cycle of the plant. However, when existing catalysts are used in fluidized beds, it is necessary to increase the reaction temperature (usually above 470°C) to obtain high conversion of methanol. Carrying out the ammoxidation reaction at high temperature easily leads to the loss of active component Mo in the catalyst, reduces the stability of the catalyst, thereby reducing the industrial application value of the catalyst, which is not conducive to the promotion of this technology. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to provide a catalyst that reduces the reaction temperature and improves stability.

[0006] The present invention solves the above technical problem through the following technical solutions:

[0007] A first aspect of the present invention provides a catalyst for preparing hydrocyanic acid in a fluidized bed, the hydrocyanic acid catalyst is a supported catalyst, the weight of the carrier accounts for 10-90% of the weight of the catalyst, and the carrier is silica sol or alumina; the general formula of the active component is Mo6Bi a Fe b Ni c X d Y e K f Z g O n ; X is selected from at least one of Mn, Te or Ta; Y is selected from at least one of Mg, Ca, K or Na; K is selected from at least one of Ce, Pr or Nd; Z is selected from at least one of V, Cr or Zr; a, b, c, d, e, f and g represent atomic ratios relative to Mo, wherein the value range of a is 0.1<a<4; the value range of b is 0.1<b<4; the value range of c is 0.5<c<5; the value range of d is 0.5<d<10; the value range of e is 0.3<e<2; the value range of f is 0.1<f<5; the value range of g is 0.1<g<2; n is the total number of oxygen atoms required to satisfy the valence of other elements.

[0008] Beneficial Effects: This invention introduces multiple metals, where metals X and Z exhibit synergistic effects to promote methanol conversion; rare earth metal K enhances the selectivity and space-time yield of hydrogen cyanide; and metal Y acts as an active site isolator, effectively isolating active sites and significantly reducing the yield of byproducts carbon monoxide and carbon dioxide. Through the interaction of different metals, this invention further lowers the reaction temperature and improves catalyst stability. The catalyst support in this invention increases the catalyst's wear resistance and synergizes with the active components, enabling it to achieve high hydrogen cyanide yields under high methanol loading and high reaction pressure.

[0009] Preferably, the value of 'a' ranges from 0.8. <a<1.5。

[0010] Preferably, the value of b ranges from 1.5. <b<3.0。

[0011] Preferably, the value of c ranges from 1.2. <c<4.5。

[0012] Preferably, the value of d ranges from 1.5. <d<2.5。

[0013] Preferably, the value of e is in the range of 0.8. <e<1.2。

[0014] Preferably, the value of f is in the range of 1.2. <f<1.5。

[0015] Preferably, the value of g is in the range of 0.8. <g<1.3。

[0016] A second aspect of the present invention provides a method for preparing the above-mentioned catalyst for fluidized bed hydrogen cyanide production, comprising the following steps: S1 dissolves the carrier in water and stirs to obtain a carrier solution; S2 dissolves ammonium heptamolybdate in water, adds acid to adjust the pH, and obtains an ammonium molybdate solution; then dissolves the nitrate corresponding to the remaining metal in water, heats and stirs, and obtains a mixed solution; the mixed solution is added to the ammonium molybdate solution to react and obtain an active solution; S3 involves mixing the support solution and the active solution, crystallizing and aging them, drying them, and calcining them to obtain the catalyst.

[0017] A third aspect of the present invention provides an application of a catalyst for fluidized bed hydrogen cyanide production, wherein the catalyst for fluidized bed hydrogen cyanide production is the above-mentioned hydrogen cyanide catalyst.

[0018] Preferably, the catalyst for producing hydrogen cyanide in a fluidized bed is reacted in a fluidized bed at a temperature of 350-450°C. Attached Figure Description

[0019] Figure 1From left to right are physical images of the hydrogen cyanide catalysts used in Examples 1, 4, and 8; Figure 2 This is a particle shape diagram of the hydrogen cyanide catalyst in Example 1 under an electron microscope; Figure 3 This is a particle shape diagram of the hydrogen cyanide catalyst in Example 4 under an electron microscope; Figure 4 This is an electron microscope image of the particle shape of the hydrogen cyanide catalyst in Example 8. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0022] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0023] Example 1 This embodiment provides a catalyst for fluidized bed hydrogen cyanide production, its preparation method, and its application, specifically including the following steps: S1 dissolves 200g of silica sol in 400g of water and stirs to obtain a silica sol solution.

[0024] S2 Dissolve 100g of ammonium heptamolybdate in 500ml of water, then add 68% concentrated nitric acid to adjust the pH of the solution to 2.5, and then heat to 60℃ to obtain an acidified ammonium molybdate solution. 22g bismuth nitrate, 40g ferric nitrate, 56g nickel nitrate, 11g manganese nitrate, 7.9g magnesium nitrate, 8.8g praseodymium nitrate, and 9.2g zirconium nitrate were dissolved in 500ml of water and heated to 60℃. Under vigorous stirring, the mixed nitrate solution was added dropwise to the acidified ammonium molybdate solution. The solution was then aged at 90℃ for 12 hours to obtain the active component solution.

[0025] S3 involves mixing and slurrying the silica sol solution and active component solution at 70°C, then transferring the mixture to an enamel crystallization reactor for crystallization and aging at 90°C for 12 hours. After crystallization and aging, the mixture is spray-dried at 350°C. Subsequently, it is calcined at 400°C for 4 hours to obtain a catalyst with a carrier mass ratio of 40%.

[0026] Based on the molar ratio of metal salt cations, the structural formula of the catalyst active component is as follows: Mo6Bi 0.94 Fe 1.98 Ni 2.47 Mn 2.43 Mg 0.95 Pr 1.24 Zr 1.05 On.

[0027] The hydrogen cyanide catalyst prepared in this embodiment was applied to the production of hydrogen cyanide from methanol via ammoxidation in a fluidized bed. The catalyst performance evaluation results are shown in Table 2. The specific parameters for evaluating the catalyst activity are as follows: Fluidized bed reactor, inner diameter 150 mm; catalyst loading: 500 g; reaction pressure: 55 kPa; Reaction temperature: 390°C; Contact time: 8 s; Space velocity: 2500 h⁻¹ -1 ; Raw material gas composition (volume ratio): Methanol: Ammonia: Air = 1:1.03:11.5; The gaseous products of the reaction were absorbed with sodium hydroxide solution and then titrated with silver nitrate.

[0028] The definitions of methanol conversion rate, hydrogen cyanide yield, hydrogen cyanide selectivity, and carbon dioxide yield are as follows: Methanol conversion rate (%) = (moles of hydrogen cyanide produced + moles of carbon dioxide produced / moles of methanol entering the reactor) × 100%; Hydrogen cyanide yield (%) = (moles of hydrogen cyanide produced / moles of methanol entering the reactor) × 100%; Hydrogen cyanide selectivity (%) = (moles of carbon in hydrogen cyanide produced / moles of carbon in all products) × 100%; Carbon dioxide yield (%) = (moles of carbon dioxide produced / moles of methanol entering the reactor) × 100%.

[0029] Example 2-10 Examples 2-10 provide a method for preparing a catalyst for fluidized bed hydrogen cyanide production, which is the same as the method in Example 1. The difference in the preparation process is that: the catalyst prepared with different molar ratios of metal salt cations in the metal component raw materials is explored, and the hydrogen cyanide catalyst is prepared according to the composition of the catalyst in Table 1. The catalyst activity evaluation conditions are as in Example 1, and the catalyst performance evaluation results are shown in Table 2.

[0030] Example 11 This embodiment provides a method for preparing a catalyst for fluidized bed hydrogen cyanide production, the obtained catalyst, and its application, specifically including the following steps: S1 dissolves 200g of silica sol in 400g of water and stirs to obtain a silica sol solution.

[0031] S2 Dissolve 100g of ammonium heptamolybdate in 500ml of water, then add 68% concentrated nitric acid to adjust the pH of the solution to 2.5, and then heat to 60℃ to obtain an acidified ammonium molybdate solution. 22g bismuth nitrate, 40g ferric nitrate, 56g nickel nitrate, 9.9g tantalum nitrate, 7.9g magnesium nitrate, 8.8g praseodymium nitrate, and 9.2g zirconium nitrate were dissolved in 500ml of water and heated to 60℃. Under vigorous stirring, the mixed nitrate solution was added dropwise to the acidified ammonium molybdate solution. The solution was then aged at 90℃ for 12 hours to obtain the active component solution.

[0032] S3 involves mixing and slurrying the silica sol solution and active component solution at 70°C, then transferring the mixture to an enamel crystallization reactor for crystallization and aging at 90°C for 12 hours. After crystallization and aging, the mixture is spray-dried at 350°C. Subsequently, it is calcined at 400°C for 4 hours to obtain a catalyst with a carrier mass ratio of 40%.

[0033] Based on the molar ratio of metal salt cations, the structural formula of the catalyst active component is as follows: Mo6Bi 0.94 Fe 1.98 Ni 2.47 Te 2.03 Mg 0.95 Pr 1.24 Zr 1.05 On.

[0034] The hydrogen cyanide catalyst prepared in this embodiment was used in the fluidized bed ammonia oxidation of methanol to produce hydrogen cyanide. The catalyst activity evaluation conditions were as in Example 1, and the catalyst performance evaluation results are shown in Table 2.

[0035] Examples 12-19 Examples 12-19 provide a method for preparing a catalyst for fluidized bed hydrogen cyanide production that is the same as the method in Example 1. The difference in the preparation process is that: the catalyst prepared with different molar ratios of metal salt cations in the metal component raw materials is explored. In addition, the amount of metal salt varies with the catalyst composition. The hydrogen cyanide catalyst is prepared according to the composition of the catalyst in Table 1. The catalyst activity evaluation conditions are the same as in Example 1. The catalyst performance evaluation results are shown in Table 2.

[0036] Example 20 This embodiment provides a method for preparing a catalyst for fluidized bed hydrogen cyanide production, the obtained catalyst, and its application, specifically including the following steps: S1 dissolves 200g of alumina in 400g of water and stirs to obtain an alumina solution.

[0037] S2 Dissolve 100g of ammonium heptamolybdate in 500ml of water, then add 68% concentrated nitric acid to adjust the pH of the solution to 2.5, and then heat to 60℃ to obtain an acidified ammonium molybdate solution. 22g bismuth nitrate, 40g ferric nitrate, 56g nickel nitrate, 9.9g tantalum nitrate, 7.9g magnesium nitrate, 8.8g praseodymium nitrate, and 9.2g zirconium nitrate were dissolved in 500ml of water and heated to 60℃. Under vigorous stirring, the mixed nitrate solution was added dropwise to the acidified ammonium molybdate solution. The solution was then aged at 90℃ for 12 hours to obtain the active component solution.

[0038] S3 involves mixing and slurrying the alumina solution and the active component solution at 70°C, then transferring the mixture to an enamel crystallization reactor for crystallization and aging at 90°C for 12 hours. After crystallization and aging, the mixture is spray-dried at 350°C. Subsequently, it is calcined at 400°C for 4 hours to obtain a catalyst with a carrier mass ratio of 40%.

[0039] Based on the molar ratio of metal salt cations, the structural formula of the catalyst active component is as follows: Mo6Bi 0.94 Fe 1.98 Ni 2.47 Te 2.03 Mg 0.95 Pr 1.24 Zr 1.05 On.

[0040] The hydrogen cyanide catalyst prepared in this embodiment was used in the fluidized bed ammonia oxidation of methanol to produce hydrogen cyanide. The catalyst activity evaluation conditions were as in Example 1, and the catalyst performance evaluation results are shown in Table 2.

[0041] Comparative Example 1 This comparative example provides a catalyst for fluidized bed hydrogen cyanide production, its preparation method, the obtained catalyst, and its application, specifically including the following steps: S1 dissolves 200g of silica sol in 400g of water and stirs to obtain a silica sol solution.

[0042] S2 Dissolve 100g of ammonium heptamolybdate in 500ml of water, then add 68% concentrated nitric acid to adjust the pH of the solution to 2.5, and then heat to 60℃ to obtain an acidified ammonium molybdate solution. 22g bismuth nitrate, 40g ferric nitrate, 56g nickel nitrate, 11g manganese nitrate, 8.8g praseodymium nitrate, and 9.2g zirconium nitrate were dissolved in 500ml of water and heated to 60℃. Under vigorous stirring, the mixed nitrate solution was added dropwise to the acidified ammonium molybdate solution. The solution was then aged at 90℃ for 12 hours to obtain the active component solution.

[0043] S3 involves mixing and slurrying the carrier solution and active component solution at 70°C, then transferring the mixture to an enamel crystallization reactor for crystallization and aging at 90°C for 12 hours. After crystallization and aging, the mixture is spray-dried at 350°C. Subsequently, it is calcined at 400°C for 4 hours to obtain a catalyst with a carrier mass ratio of 40%.

[0044] Based on the molar ratio of metal salt cations, the structural formula of the catalyst active component is as follows: Mo6Bi 0.94 Fe 1.98 Ni 2.47 Mn 2.43 Pr 1.24 Zr 1.05 On.

[0045] The hydrogen cyanide catalyst prepared in this comparative example was used in the fluidized bed ammonia oxidation of methanol to produce hydrogen cyanide. The catalyst activity was evaluated under the conditions described in Example 1, and the catalyst performance evaluation results are shown in Table 2.

[0046] Comparative Examples 2-8 Comparative Examples 2-8 provide a method for preparing a catalyst for fluidized bed hydrogen cyanide production that is the same as the method in Example 1. The difference in the preparation process is that the influence of reducing metal salt cations on catalyst performance is investigated. Therefore, at least one metal salt cation is reduced during the preparation process. In addition, the amount of metal salt varies with the catalyst composition. The hydrogen cyanide catalyst is prepared according to the catalyst composition in Table 1. The catalyst activity evaluation conditions are the same as in Example 1, and the catalyst evaluation results are shown in Table 2.

[0047] Table 1 Catalyst Components

[0048] Table 2 Catalyst performance evaluation results

[0049] As can be seen from Tables 1 and 2, the hydrogen cyanide catalysts prepared in the examples have good hydrogen cyanide yield and selectivity in the methanol ammonia oxidation reaction, which can meet the needs of industrial production. Among them, the catalysts in Examples 1-10 have very good performance.

[0050] Based on the data from the comparative examples and comparative samples, it can be seen that the MoBiFeNi catalyst of the present invention cannot reduce its auxiliary metals accordingly. If one or two metals are reduced, the catalyst performance will be significantly weakened, and the yield of the byproduct carbon dioxide will increase.

[0051] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A catalyst for fluidized bed hydrogen cyanide production, characterized in that, The hydrogen cyanide catalyst is a supported catalyst, with the support accounting for 10-90% of the catalyst weight. The support is silica sol or alumina, and its active component has the general formula Mo6Bi. a Fe b Ni c X d Y e K f Z g O n ; X is selected from at least one of Mn, Te or Ta; Y is selected from at least one of Mg, Ca, K or Na; K is selected from at least one of Ce, Pr or Nd; Z is selected from at least one of V, Cr or Zr; a, b, c, d, e, f and g represent atomic ratios relative to Mo, wherein the value range of a is 0.1<a<4; the value range of b is 0.1<b<4; the value range of c is 0.5<c<5; the value range of d is 0.5<d<10; the value range of e is 0.3<e<2; the value range of f is 0.1<f<5; the value range of g is 0.1<g<2; n is the total number of oxygen atoms required to satisfy the valence of other elements.

2. The catalyst for fluidized bed hydrogen cyanide production according to claim 1, characterized in that, The value range of said a is 0.8<a<1.

5.

3. The catalyst for fluidized bed hydrogen cyanide production according to claim 1, characterized in that, The value range of said b is 1.5<b<3.

0.

4. The catalyst for fluidized bed hydrogen cyanide production according to claim 4, characterized in that, The value range of said c is 1.2<c<4.

5.

5. The catalyst for fluidized bed hydrogen cyanide production according to claim 1, characterized in that, The value range of said d is 1.5<d<2.

5.

6. The catalyst for fluidized bed hydrogen cyanide production according to claim 1, characterized in that, The value range of said e is 0.8<e<1.

2.

7. The catalyst for fluidized bed hydrogen cyanide production according to claim 1, characterized in that, The value range of said f is 1.2<f<2.5; the value range of said g is 0.8<g<1.

3.

8. A method for preparing a catalyst for fluidized bed hydrogen cyanide production as described in any one of claims 1-7, characterized in that, comprises the following steps: S1: dissolving a carrier in water and stirring to obtain a carrier solution; S2: dissolving ammonium heptamolybdate in water and adding an acid to adjust pH, so as to obtain an ammonium molybdate solution; then dissolving nitrates corresponding to the remaining metals in water, heating and stirring to obtain a mixed solution; adding the mixed solution to the ammonium molybdate solution for reaction to obtain an active solution; S3: subjecting the carrier solution and the active solution to mixing, crystallization and aging, drying and roasting treatment to obtain a hydrocyanic acid catalyst.

9. An application of a catalyst for fluidized bed hydrogen cyanide production, characterized in that: The hydrocyanic acid catalyst used for a fluidized bed is the hydrocyanic acid catalyst described in any one of claims 1 to 7.

10. The application according to claim 9, characterized in that: The reaction of the hydrocyanic acid catalyst used for the fluidized bed is carried out in a fluidized bed, and the reaction temperature is 350-450°C.

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