Fixed bed hydrogenation catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of caprolactam production, in particular to a fixed bed hydrogenation catalyst and a preparation method thereof.The fixed bed hydrogenation catalyst at least comprises an activated carbon-based carrier and a nickel salt solution, the specific surface area of the activated carbon-based carrier is larger than or equal to 400 m < 2 > / g, the pore volume of the activated carbon-based carrier is larger than or equal to 0.3 mL / g, and the strength of the activated carbon-based carrier is larger than or equal to 90%; activated carbon is selected as a carrier, the carrier is shaped into an amorphous shape, a cylindrical shape, a clover shape and the like, the carrier with high strength and high specific surface area is obtained, and the acid-resistant, alkali-resistant and water-resistant fixed bed hydrogenation catalyst is obtained by carrying out load modification, drying and activation on the carrier. And the application requirement of unsaturated hydrocarbon hydrogenation reaction of the crude caprolactam aqueous solution in a caprolactam device is met.

Description

Technical Field

[0001] The present invention relates to the technical field of caprolactam production, and specifically to a fixed-bed hydrogenation catalyst and a preparation method thereof. Background Art

[0002] The production steps of caprolactam mainly include processes such as benzene hydrogenation to cyclohexane, cyclohexane oxidation to cyclohexanone, cyclohexanone oximation to cyclohexanone oxime, and cyclohexanone oxime rearrangement to produce caprolactam. Due to the complex production process of caprolactam, some unsaturated by-products other than caprolactam will inevitably be generated. The physical and chemical properties of these unsaturated by-products are very similar to those of caprolactam, and it is difficult to remove them through refining methods such as extraction and distillation. Since the presence of unsaturated by-products will affect the polymerization process of caprolactam, thereby reducing the quality of the polymerized product, it is necessary to remove the unsaturated by-products.

[0003] Industrially, the hydrogenation method is often selected to treat unsaturated by-products. After saturation, the by-products and caprolactam have differences in boiling point and solubility, so that the unsaturated by-products can be removed through extraction, distillation, and crystallization processes to achieve the purpose of refining caprolactam and meet the process requirements of production. Currently, there are mainly two methods for hydrogenating and saturating unsaturated by-products industrially. One is to use a stirred tank reactor and select powdered Raney nickel as the hydrogenation catalyst. During its use, it often flows to the downstream. Not only does the upstream need to continuously supplement the catalyst, but the downstream filter also needs to be cleaned regularly, generating a large amount of dangerous waste. Moreover, during the treatment process of the reduced nickel, it will be exposed to the air and will spontaneously combust, which is very dangerous. The other is through a fixed-bed reactor, selecting nickel as the active component supported on an alumina carrier. This process flow is continuous and simple, and the operation is simple. However, its pH requirement for raw materials is extremely strict. Being too acidic or too alkaline will cause the loss of the carrier, thereby affecting the service life of the catalyst. Therefore, the caprolactam aqueous solution must be treated with acid and base resins before entering the hydrogenation catalytic process. Especially at present, the industry is facing upgrading, and many domestic devices are considering removing the acid and base treatment devices. If the caprolactam device is not treated with acid and base resins, then its service life will be seriously affected.

[0004] Therefore, developing a new type of fixed-bed hydrogenation catalyst that is acid-resistant, alkali-resistant, and water-resistant is the development trend of the industry and has broad application prospects. Summary of the Invention

[0005] In order to solve the above problems, the present invention selects activated carbon as the carrier, shapes it into irregular shapes, cylindrical shapes, cloverleaf shapes, etc. to obtain a carrier with high strength and high specific surface area, and through load modification, drying, and activation, a fixed-bed hydrogenation catalyst that is acid-resistant, alkali-resistant, and water-resistant is obtained, meeting the application requirements of the unsaturated hydrocarbon hydrogenation reaction of the crude caprolactam aqueous solution in the caprolactam device.

[0006] On the one hand, the present invention provides a fixed-bed hydrogenation catalyst, and the preparation raw materials thereof at least include: an activated carbon-based carrier and a nickel salt solution. The specific surface area of the activated carbon-based carrier is ≥ 400 m 2 / g, the pore volume of the activated carbon-based carrier is ≥ 0.3 mL / g, and the strength of the activated carbon-based carrier is ≥ 80%.

[0007] As a preferred technical solution, the preparation raw materials of the fixed-bed hydrogenation catalyst further include at least one of a transition metal salt solution, an alkaline earth metal salt solution, and an alkali metal salt solution.

[0008] Preferably, the transition metal salt solution is selected from at least one of an aqueous titanium sulfate solution and an aqueous titanium chloride solution.

[0009] Preferably, the alkaline earth metal salt solution is selected from at least one of an aqueous magnesium sulfate solution and an aqueous magnesium chloride solution.

[0010] As a preferred technical solution, the alkali metal salt solution is selected from at least one of an aqueous sodium chloride solution, an aqueous lithium chloride solution, and an aqueous potassium chloride solution.

[0011] As a preferred technical solution, the nickel salt solution is selected from at least one of an aqueous nickel formate solution, an aqueous nickel nitrate solution, an aqueous nickel chloride solution, an aqueous nickel sulfate solution, and an aqueous nickel acetate solution.

[0012] As a preferred technical solution, the shape of the activated carbon-based carrier is one of amorphous, cylindrical, and clover-shaped.

[0013] As a preferred technical solution, the activated carbon matrix in the activated carbon-based carrier is one of wood charcoal, coconut shell charcoal, and coal-based carbon.

[0014] As a preferred technical solution, the specific surface area of the activated carbon-based carrier is ≥ 400 m 2 / g, preferably 550 - 1000 m 2 / g (Determination of pore volume and specific surface area - Test method for granular activated carbon from coal - GB / T 7702.20 - 2008).

[0015] As a preferred technical solution, the pore volume of the activated carbon-based carrier is ≥ 0.3 mL / g, preferably 0.35 - 0.56 mL / g (Determination of pore volume and specific surface area - Test method for granular activated carbon from coal - GB / T 7702.20 - 2008).

[0016] As a preferred technical solution, the strength of the activated carbon-based carrier is ≥ 80% (Determination of strength - Test method for wood-based activated carbon - GB / T 12496.6 - 1999).

[0017] On the other hand, the present invention provides a method for preparing a fixed-bed hydrogenation catalyst, which at least includes the following steps:

[0018] (1) Mix the raw materials except the activated carbon-based carrier to form a mixed metal salt solution;

[0019] (2) Perform multiple ion exchanges on the metal salt solution and the activated carbon-based carrier. After each ion exchange, dry it at 70 - 90 °C for 2 - 4 h and then perform the next ion exchange until the content of nickel oxide in the activated carbon-based carrier is 20 - 40 wt%, the content of alkaline earth metal oxide or transition metal oxide is 0 - 5 wt%, the content of alkali metal oxide is 0 - 5 wt%, and then activate it at 350 - 450 °C for 1 - 3 h to obtain the fixed-bed hydrogenation catalyst.

[0020] By using an activated carbon-based carrier with a specific surface area, pore volume, and strength within a certain range for the preparation of the fixed-bed hydrogenation catalyst, the present invention reduces the loading difficulty of the active components, ensures the loading of nickel oxide, alkaline earth metal oxide or transition metal oxide, and alkali metal oxide in the prepared fixed-bed hydrogenation catalyst, and guarantees the subsequent application effect.

[0021] Furthermore, the present invention performs load modification on the activated carbon-based carrier by using a mixed metal salt solution containing nickel salt, alkali metal salt, transition metal salt solution or alkaline earth metal salt solution. In particular, by controlling the content of nickel oxide in the obtained activated carbon-based carrier to be 20 - 40 wt%, the content of transition metal oxide or alkaline earth metal oxide to be 1.5 - 5 wt%, and the content of alkali metal oxide to be 1 - 5 wt%, it can achieve long-term operation of hydrogenation catalysis in acid-water environment and alkali-water environment, ensure that the PAN value after hydrogenation is less than 1, and meet the industrial requirements.

[0022] Beneficial effects

[0023] 1. The present invention selects activated carbon as the carrier, forms it into irregular shapes, cylindrical shapes, clover shapes, etc., to obtain a carrier with high strength and high specific surface area. Through load modification, drying, and activation, a fixed-bed hydrogenation catalyst that is resistant to acid, alkali, and water is obtained, meeting the application requirements of the unsaturated hydrocarbon hydrogenation reaction of crude caprolactam aqueous solution in the caprolactam device.

[0024] 2. By using an activated carbon-based carrier with a specific surface area, pore volume, and strength within a certain range for the preparation of the fixed-bed hydrogenation catalyst, the present invention reduces the loading difficulty of the active components, ensures the loading of nickel oxide, alkaline earth metal oxide or transition metal oxide, and alkali metal oxide in the prepared fixed-bed hydrogenation catalyst, and guarantees the subsequent application effect.

[0025] 3. The present invention modifies the activated carbon-based carrier by loading it with a mixed metal salt solution containing nickel salt, alkali metal salt, transition metal salt solution or alkaline earth metal salt solution. In particular, the content of nickel oxide in the obtained activated carbon-based carrier is controlled to be 20-40 wt%, the content of transition metal oxide or alkaline earth metal oxide is 1.5-5 wt%, and the content of alkali metal oxide is 1-5 wt%. This can achieve long-term operation of hydrogenation catalysis in acid-aqueous environment and alkali-aqueous environment, ensure that the PAN value after hydrogenation is less than 1, and meet the industrial requirements.

[0026] 4. The fixed-bed hydrogenation catalyst of the present invention can be directly used for the saturation treatment of unsaturated by-products in crude caprolactam solution, thereby removing the unsaturated by-products in the crude caprolactam and achieving the purpose of refining caprolactam. This greatly shortens the process flow and equipment investment, and has higher economic feasibility. Specific embodiments

[0027] Example 1

[0028] On the one hand, Example 1 of the present invention provides a fixed-bed hydrogenation catalyst, and its preparation raw materials include: activated carbon-based carrier, nickel salt solution, transition metal salt solution, alkali metal salt solution.

[0029] The transition metal salt solution is an aqueous solution of titanium sulfate.

[0030] The alkali metal salt solution is an aqueous solution of lithium chloride.

[0031] The nickel salt solution is an aqueous solution of nickel formate.

[0032] The shape of the activated carbon-based carrier is amorphous. The activated carbon matrix in the activated carbon-based carrier is wood-based activated carbon. The specific surface area of the activated carbon-based carrier is 850 m 2 / g (Determination of pore volume and specific surface area of coal-based granular activated carbon - Test method of GB / T 7702.20-2008). The pore volume of the activated carbon-based carrier is 0.56 mL / g (Determination of pore volume and specific surface area of coal-based granular activated carbon - Test method of GB / T 7702.20-2008). The strength of the activated carbon-based carrier is 95% (Determination of strength of wood-based activated carbon - Test method of GB / T12496.6-1999). The amorphous wood-based activated carbon is sourced from Fujian Yuanli Activated Carbon Co., Ltd.

[0033] On the other hand, Example 1 of the present invention provides a preparation method of a fixed-bed hydrogenation catalyst, including the following steps:

[0034] (1) Mix a 1 mol / L nickel salt solution, a 1 mol / L transition metal salt solution, and a 1 mol / L alkali metal salt solution to form a mixed metal salt solution;

[0035] (2) The metal salt solution is subjected to multiple ion exchanges with the activated carbon-based support. After each ion exchange, it is dried at 80 °C for 3 h and then subjected to the next ion exchange until the content of nickel oxide in the activated carbon-based support is 20 wt%, the transition metal oxide (titanium oxide) is 1.5 wt%, and the alkali metal oxide (lithium oxide) is 1 wt%. The impregnated catalyst is dried at 80 °C for 3 h and then activated at 350 °C for 2 h to obtain the fixed-bed hydrogenation catalyst.

[0036] Example 2

[0037] Example 2 of the present invention provides a fixed-bed hydrogenation catalyst and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that the shape of the activated carbon-based support is cylindrical, the specific surface area of the activated carbon-based support is 602 m 2 / g, the pore volume of the activated carbon-based support is 0.38 mL / g, and the strength of the activated carbon-based support is 81%; the preparation method of the activated carbon-based support is as follows: 1) Wood-based activated carbon (73 wt%), tar (25 wt%), and methylcellulose (2 wt%) are added to a kneader and kneaded, and an appropriate amount of deionized water is added and kneaded evenly; 2) It is placed in a screw-type extruder and extruded into a cylindrical shape using a Φ3.2 mm cylindrical mold, dried in an oven at 80 °C for 3 h, and calcined in a nitrogen atmosphere. The calcination temperature is 350 °C, and it is calcined for 2 h to obtain the activated carbon-based support. The transition metal salt solution is replaced with an aqueous magnesium sulfate solution, the alkali metal salt solution is an aqueous sodium chloride solution, and the nickel salt solution is an aqueous nickel chloride solution. In step (2), the content of nickel oxide in the activated carbon-based support is controlled to be 30 wt%, the alkaline earth metal oxide (magnesium oxide) is 4 wt%, and the alkali metal oxide (sodium oxide) is 3 wt%. The impregnated catalyst is dried at 80 °C for 4 h and then activated at 380 °C for 2 h to obtain the fixed-bed hydrogenation catalyst.

[0038] Example 3

[0039] Example 3 of the present invention provides a fixed-bed hydrogenation catalyst and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that the shape of the activated carbon-based support is clover-shaped, the specific surface area of the activated carbon-based support is 589 m 2 / g, the pore volume of the activated carbon-based carrier is 0.40 mL / g, and the strength of the activated carbon-based carrier is 80%; the preparation method of the activated carbon-based carrier is as follows: 1) Add woody activated carbon (70 wt%), tar (27 wt%), and methyl cellulose (3 wt%) into a kneader and knead, add an appropriate amount of deionized water and knead evenly; add an appropriate amount of deionized water and knead evenly; 2) Place it in a screw extruder, use a Φ3.2 mm clover-shaped mold to extrude and form, place it in an 80°C oven and dry for 5 h, calcine in a nitrogen atmosphere, the calcination temperature is 400°C, and calcine for 2 h to obtain the activated carbon-based carrier. The transition metal salt solution is replaced with an aqueous magnesium chloride solution, the alkali metal salt solution is an aqueous potassium chloride solution, and the nickel salt solution is an aqueous nickel acetate solution. In step (2), the content of nickel oxide in the activated carbon-based carrier is controlled to be 35 wt%, alkaline earth metal oxide (magnesium oxide) 5 wt%, and alkali metal oxide (potassium oxide) 5 wt%. The impregnated catalyst is dried at 100°C for 4 h and activated at 400°C for 2 h to obtain the fixed-bed hydrogenation catalyst.

[0040] Example 4

[0041] Example 4 of the present invention provides a fixed-bed hydrogenation catalyst and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that the shape of the activated carbon-based carrier is clover-shaped, and the specific surface area of the activated carbon-based carrier is 589 m 2 / g, the pore volume of the activated carbon-based carrier is 0.40 mL / g, and the strength of the activated carbon-based carrier is 80%; the preparation method of the activated carbon-based carrier is as follows: 1) Add woody activated carbon (70 wt%), tar (27 wt%), and methyl cellulose (3 wt%) into a kneader and knead, add an appropriate amount of deionized water and knead evenly; 2) Place it in a screw extruder, use a Φ3.2 mm clover-shaped mold to extrude and form, place it in an 80°C oven and dry for 6 h, calcine in a nitrogen atmosphere, the calcination temperature is 450°C, and calcine for 2 h to obtain the activated carbon-based carrier. The raw materials for preparing the fixed-bed hydrogenation catalyst include: activated carbon-based carrier, aqueous nickel nitrate solution. In step (2), the content of nickel oxide in the activated carbon-based carrier is controlled to be 40 wt%. The impregnated catalyst is dried at 120°C for 4 h and activated at 450°C for 2 h to obtain the fixed-bed hydrogenation catalyst.

[0042] Example 5

[0043] Example 5 of the present invention provides a fixed-bed hydrogenation catalyst and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that the activated carbon matrix in the activated carbon-based carrier is amorphous coconut shell activated carbon, and the specific surface area of the activated carbon-based carrier is 978 m 2 / g, the pore volume of the activated carbon-based support is 0.54 mL / g, the strength of the activated carbon-based support is 94%, and the amorphous coconut shell activated carbon is sourced from Fujian Yuanli Activated Carbon Co., Ltd.

[0044] Example 6

[0045] Example 6 of the present invention provides a fixed-bed hydrogenation catalyst and its preparation method. The specific implementation is the same as that of Example 1, except that the shape of the activated carbon-based support is cylindrical, the activated carbon matrix in the activated carbon-based support is coconut shell carbon, and the specific surface area of the activated carbon-based support is 698 m 2 / g, the pore volume of the activated carbon-based support is 0.38 mL / g, and the strength of the activated carbon-based support is 83%; the preparation method of the activated carbon-based support is as follows: 1) Add coconut shell activated carbon (70 wt%), tar (28 wt%), and methylcellulose (2 wt%) into a kneading machine for kneading, and add an appropriate amount of deionized water to knead evenly; 2) Place it in a screw-type extrusion machine and extrude it into shape using a cylindrical mold with a diameter of Φ3.2 mm, dry it in an oven at 80°C for 6 h, and calcine it in a nitrogen atmosphere. The calcination temperature is 450°C, and calcine for 2 h to obtain the activated carbon-based support. The transition metal salt solution is replaced with an aqueous magnesium sulfate solution, the alkali metal salt solution is an aqueous sodium chloride solution, and the nickel salt solution is an aqueous nickel chloride solution. In step (2), the content of nickel oxide in the activated carbon-based support is controlled to be 30 wt%, alkaline earth metal oxide (magnesium oxide) 4 wt%, and alkali metal oxide (sodium oxide) 3 wt%. After impregnation, the catalyst is dried at 120°C for 4 h and activated at 450°C for 2 h to obtain the fixed-bed hydrogenation catalyst.

[0046] Example 7

[0047] Example 7 of the present invention provides a fixed-bed hydrogenation catalyst and its preparation method. The specific implementation is the same as that of Example 1, except that the shape of the activated carbon-based support is clover-shaped, the activated carbon matrix in the activated carbon-based support is coconut shell carbon, and the specific surface area of the activated carbon-based support is 667 m 2 / g, the pore volume of the activated carbon-based carrier is 0.36 mL / g, and the strength of the activated carbon-based carrier is 81%; the preparation method of the activated carbon-based carrier is as follows: 1) Mix coconut shell activated carbon (75 wt%) and tar (25 wt%) in a kneader, and add an appropriate amount of deionized water to knead evenly; 2) Place it in a screw-type extruder, use a Φ3.2 mm clover-shaped die to extrude into shape, place it in an 80°C oven and dry for 5 h, and calcine in a nitrogen atmosphere. The calcination temperature is 400°C, and calcine for 2 h to obtain the activated carbon-based carrier. The transition metal salt solution is replaced with an aqueous magnesium chloride solution, the alkali metal salt solution is an aqueous potassium chloride solution, and the nickel salt solution is an aqueous nickel acetate solution. In step (2), the content of nickel oxide in the activated carbon-based carrier is controlled to be 35 wt%, alkaline earth metal oxide (magnesium oxide) 5 wt%, and alkali metal oxide (potassium oxide) 5 wt%. The impregnated catalyst is dried at 100°C for 4 h and activated at 400°C for 2 h to obtain the fixed-bed hydrogenation catalyst.

[0048] Example 8

[0049] Example 8 of the present invention provides a fixed-bed hydrogenation catalyst and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that the shape of the activated carbon-based carrier is clover-shaped, the activated carbon matrix in the activated carbon-based carrier is coconut shell carbon, and the specific surface area of the activated carbon-based carrier is 667 m 2 / g, the pore volume of the activated carbon-based carrier is 0.36 mL / g, and the strength of the activated carbon-based carrier is 81%; the preparation method of the activated carbon-based carrier is as follows: 1) Mix coconut shell activated carbon (80 wt%) and tar (20 wt%) in a kneader, and add an appropriate amount of deionized water to knead evenly; 2) Place it in a screw-type extruder, use a Φ3.2 mm clover-shaped die to extrude into shape, place it in an 80°C oven and dry for 4 h, and calcine in a nitrogen atmosphere. The calcination temperature is 380°C, and calcine for 2 h to obtain the activated carbon-based carrier. The raw materials for preparing the fixed-bed hydrogenation catalyst include: activated carbon-based carrier, aqueous nickel nitrate solution. In step (2), the content of nickel oxide in the activated carbon-based carrier is controlled to be 40 wt%. The impregnated catalyst is dried at 80°C for 4 h and activated at 380°C for 2 h to obtain the fixed-bed hydrogenation catalyst.

[0050] Example 9

[0051] Example 9 of the present invention provides a fixed-bed hydrogenation catalyst and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that the activated carbon matrix in the activated carbon-based carrier is coal-based carbon, and the specific surface area of the activated carbon-based carrier is 868 m 2 / g, the pore volume of the activated carbon-based support is 0.55 mL / g, and the strength of the activated carbon-based support is 97%; the coal-based carbon is sourced from Fujian Yuanli Activated Carbon Co., Ltd. The preparation method of the activated carbon-based support is as follows: 1) Mix coal-based activated carbon (70 wt%), tar (25 wt%), and methylcellulose (5 wt%) in a kneader, and add an appropriate amount of deionized water and knead evenly; 2) Place it in a screw-type extruder, extrude and form using a cylindrical mold with a diameter of Φ3.2 mm, dry it in an oven at 100 °C for 4 h, and calcine it in a nitrogen atmosphere. The calcination temperature is 380 °C, and calcine for 2 h to obtain the activated carbon-based support. The transition metal salt solution is replaced with an aqueous magnesium sulfate solution, the alkali metal salt solution is an aqueous sodium chloride solution, and the nickel salt solution is an aqueous nickel chloride solution. In step (2), the content of nickel oxide in the activated carbon-based support is controlled to be 30 wt%, alkaline earth metal oxide (magnesium oxide) 4 wt%, and alkali metal oxide (sodium oxide) 3 wt%. The impregnated catalyst is dried at 80 °C for 4 h and activated at 380 °C for 2 h to obtain the fixed-bed hydrogenation catalyst.

[0052] Example 10

[0053] Example 10 of the present invention provides a fixed-bed hydrogenation catalyst and its preparation method. The specific implementation is the same as that of Example 1, except that the shape of the activated carbon-based support is clover-shaped, the activated carbon matrix in the activated carbon-based support is coal-based carbon, and the specific surface area of the activated carbon-based support is 550 m 2 / g, the pore volume of the activated carbon-based support is 0.37 mL / g, and the strength of the activated carbon-based support is 80%; the preparation method of the activated carbon-based support is as follows: 1) Mix coal-based carbon (80 wt%), tar (18 wt%), and methylcellulose (2 wt%) in a kneader, and add an appropriate amount of deionized water and knead evenly; 2) Place it in a screw-type extruder, extrude and form using a Φ3.2 mm clover-shaped mold, dry it in an oven at 80 °C for 5 h, and calcine it in a nitrogen atmosphere. The calcination temperature is 400 °C, and calcine for 2 h to obtain the activated carbon-based support. The transition metal salt solution is replaced with an aqueous magnesium chloride solution, the alkali metal salt solution is an aqueous potassium chloride solution, and the nickel salt solution is an aqueous nickel acetate solution. In step (2), the content of nickel oxide in the activated carbon-based support is controlled to be 35 wt%, alkaline earth metal oxide (magnesium oxide) 5 wt%, and alkali metal oxide (potassium oxide) 5 wt%. The impregnated catalyst is dried at 100 °C for 4 h and activated at 400 °C for 2 h to obtain the fixed-bed hydrogenation catalyst.

[0054] Example 11

[0055] Example 11 of the present invention provides a fixed-bed hydrogenation catalyst and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that the shape of the activated carbon-based carrier is clover-shaped, the activated carbon matrix in the activated carbon-based carrier is coal-based carbon, the specific surface area of the activated carbon-based carrier is 550 m 2 / g, the pore volume of the activated carbon-based carrier is 0.37 mL / g, and the strength of the activated carbon-based carrier is 80%; the preparation method of the activated carbon-based carrier is as follows: 1) Add coal-based carbon (69 wt%), tar (30 wt%), and methylcellulose (1 wt%) into a kneader and knead, add an appropriate amount of deionized water and knead evenly; 2) Place it in a screw-type extruder, use a Φ3.2 mm clover-shaped mold to extrude and form, place it in an oven at 80 °C and dry for 6 h, calcine in a nitrogen atmosphere, the calcination temperature is 450 °C, and calcine for 2 h to obtain the activated carbon-based carrier. The preparation raw materials of the fixed-bed hydrogenation catalyst include: an activated carbon-based carrier and an aqueous nickel nitrate solution. In step (2), the content of nickel oxide in the activated carbon-based carrier is controlled to be 40 wt%. The impregnated catalyst is dried at 120 °C for 4 h and activated at 450 °C for 2 h to obtain the fixed-bed hydrogenation catalyst.

[0056] Comparative Example 1

[0057] Comparative Example 1 of the present invention provides a fixed-bed hydrogenation catalyst and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that the activated carbon-based carrier is replaced with an activated alumina carrier. The shape of the activated alumina carrier is spherical, and the specific surface area of the activated alumina carrier is 138 m 2 / g, the pore volume of the activated alumina carrier is 0.37 mL / g, and the strength of the activated alumina carrier is 65 N (HG / T 3927-2020 Industrial Activated Alumina). The transition metal salt solution is replaced with an aqueous magnesium sulfate solution, the alkali metal salt solution is an aqueous sodium chloride solution, and the nickel salt solution is an aqueous nickel chloride solution. In step (2), the content of nickel oxide in the activated carbon-based carrier is controlled to be 30 wt%, 4 wt% of alkaline earth metal oxide (magnesium oxide), and 3 wt% of alkali metal oxide (sodium oxide).

[0058] Comparative Example 2

[0059] Comparative Example 2 of the present invention provides a fixed-bed hydrogenation catalyst and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that the activated carbon-based carrier is replaced with an activated alumina carrier. The shape of the activated alumina carrier is cylindrical, and the specific surface area of the activated alumina carrier is 145 m 2 / g, the pore volume of the activated alumina support is 0.36 mL / g, and the strength of the activated alumina support is 48 N (custom-produced by Zibo Runteng New Material Technology Co., Ltd.). The transition metal salt solution is replaced with an aqueous magnesium chloride solution, the alkali metal salt solution is an aqueous potassium chloride solution, and the nickel salt solution is an aqueous nickel acetate solution. In step (2), the content of nickel oxide in the activated carbon-based support is controlled to be 35 wt%, alkaline earth metal oxide (magnesium oxide) 5 wt%, and alkali metal oxide (potassium oxide) 5 wt%.

[0060] Comparative Example 3

[0061] Comparative Example 3 of the present invention provides a fixed-bed hydrogenation catalyst and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that the activated carbon-based support is replaced with an activated alumina support. The shape of the activated alumina support is clover-shaped, and the specific surface area of the activated alumina support is 162 m 2 / g, the pore volume of the activated alumina support is 0.38 mL / g, and the strength of the activated alumina support is 52 N (custom-produced by Zibo Runteng New Material Technology Co., Ltd.). The transition metal salt solution is replaced with an aqueous magnesium chloride solution, the alkali metal salt solution is an aqueous potassium chloride solution, and the nickel salt solution is an aqueous nickel acetate solution. The raw materials for preparing the fixed-bed hydrogenation catalyst include: an activated carbon-based support, an aqueous nickel nitrate solution. In step (2), the content of nickel oxide in the activated carbon-based support is controlled to be 40 wt%.

[0062] Performance test method

[0063] A fixed-bed reactor was used to evaluate the fixed-bed hydrogenation catalysts prepared in the examples and comparative examples. The results are shown in Table 1. Evaluation means: the potassium permanganate absorption value (PAN value) at the hydrogenation outlet of the caprolactam plant. Test method: GB / T 13255.3-2009 Test methods for industrial caprolactam - Part 3: Determination of potassium permanganate absorption value - Spectrophotometric method.

[0064] Reaction conditions: pressure 0.4 MPa, temperature 45 °C;

[0065] Caprolactam raw material composition: caprolactam 35 wt%, water 64 wt%, unsaturated hydrocarbons 1.0 wt%, raw material PM value: ≥ 300 s;

[0066] Caprolactam raw material pH value: pH = 5 and pH = 9;

[0067] Feed flow rate: 10 L / h, hydrogen flow rate 15%;

[0068] Space velocity: 6 h -1 .

[0069] Table 1

[0070]

[0071] It can be seen from the data in Table 1 that after the catalysts provided in Examples 1-11 are used in the caprolactam plant as compared with the catalysts provided in Comparative Examples 1-3, lower outlet potassium permanganate absorption values can be obtained under both acidic and alkaline conditions.

Claims

1. A fixed bed hydrogenation catalyst, characterized in that The raw materials for its preparation include at least: an activated carbon-based carrier and a nickel salt solution, wherein the specific surface area of ​​the activated carbon-based carrier is ≥400m 2 / g, the pore volume of the activated carbon-based carrier is ≥0.3mL / g, and the strength of the activated carbon-based carrier is ≥90%.

2. The fixed bed hydrogenation catalyst according to claim 1, characterized in that The raw material for preparing the fixed bed hydrogenation catalyst also includes at least one of a transition metal salt solution, an alkaline earth metal salt solution, and an alkali metal salt solution.

3. The fixed bed hydrogenation catalyst according to claim 2, characterized in that The transition metal salt solution is selected from at least one of a titanium sulfate aqueous solution and a titanium chloride aqueous solution.

4. The fixed bed hydrogenation catalyst according to claim 2, characterized in that The alkaline earth metal salt solution is selected from at least one of a magnesium sulfate aqueous solution and a magnesium chloride aqueous solution.

5. The fixed bed hydrogenation catalyst according to claim 2, characterized in that The alkali metal salt solution is selected from at least one of a sodium chloride aqueous solution and a potassium chloride aqueous solution.

6. The fixed bed hydrogenation catalyst according to claim 1, characterized in that The nickel salt solution is selected from at least one of a nickel formate aqueous solution, a nickel nitrate aqueous solution, a nickel chloride aqueous solution, a nickel sulfate aqueous solution, and a nickel acetate aqueous solution.

7. The fixed bed hydrogenation catalyst according to claim 1, characterized in that The shape of the activated carbon-based carrier is one of amorphous, cylindrical, and clover-shaped.

8. The use of the fixed bed hydrogenation catalyst according to claim 1, characterized in that: The activated carbon matrix in the activated carbon-based carrier is one of wood charcoal, coconut shell charcoal and coal charcoal.

9. The use of the fixed bed hydrogenation catalyst according to claim 5, characterized in that: The specific surface area of ​​the activated carbon-based carrier is 550-1000m 2 / g, and the pore volume of the activated carbon-based carrier is 0.35-0.56mL / g.

10. A method for preparing a fixed bed hydrogenation catalyst according to any one of claims 1 to 9, characterized in that: At least the following steps are included: (1) mixing raw materials except the activated carbon-based carrier into a mixed metal salt solution; (2) The metal salt solution and the activated carbon-based carrier are subjected to multiple ion exchanges. After each ion exchange, the catalyst is dried at 70-90° C. for 2-4 hours and then subjected to the next ion exchange until the content of nickel oxide in the activated carbon-based carrier is 20-40wt%, the content of alkaline earth metal oxide or transition metal oxide is 0-5wt%, and the content of alkali metal oxide is 0-5wt%. After activation at 350-450° C. for 1-3 hours, a fixed bed hydrogenation catalyst is obtained.

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