Hydrogenation catalyst, preparation method thereof and application of hydrogenation catalyst in light liquid paraffin separation

Abstract

The invention provides a hydrogenation catalyst as well as a preparation method and application thereof in light liquid paraffin separation, and relates to the technical field of petrochemical industry. The preparation method provided by the invention comprises the following steps: carrying out mixed coordination on an organic ligand, nickel ions and zinc ions to prepare a composite MOF (Metal Organic Framework); calcining the composite MOF at a high temperature of 300-500 DEG C in a nitrogen atmosphere to obtain a catalytic precursor; dipping the catalytic precursor in a molybdenum-containing solution, and separating to obtain a catalytic intermediate; and reducing the catalytic intermediate in a reducing gas at 300-450 DEG C to obtain the hydrogenation catalyst. The catalytic stability and catalytic activity of the hydrogenation catalyst can be effectively improved, the production cost of liquid paraffin can be effectively reduced, and the hydrogenation production efficiency can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petroleum chemical industry, and particularly relates to a hydrogenation catalyst, a preparation method thereof and application of the hydrogenation catalyst in separation of light liquid paraffin. BACKGROUND

[0002] The light liquid paraffin is a saturated alkane mixture extracted from petroleum distillate, mainly composed of straight-chain and / or branched-chain alkanes with carbon chain length of C10-C15, and has the characteristics of colorless, odorless, low viscosity and high chemical stability, and belongs to the middle distillate product in the petroleum refining process. In addition, the light liquid paraffin is widely used in the fields of medicine, cosmetics, food processing and the like due to its low toxicity and chemical inertness, and specifically, in the medical field, the light liquid paraffin is usually used as an ointment base, a suppository lubricant and a drug sustained-release carrier, and in the cosmetic field, the light liquid paraffin is usually used as a moisturizing agent or a makeup remover oil component.

[0003] In the prior art, the light liquid paraffin is usually produced by using the naphtha fraction as a raw material and prepared by a molecular sieve dewaxing technology. The Chinese patent with the publication number CN106675649A provides a method for preparing coal-based light liquid paraffin from coal indirect liquefied oil products, which specifically includes mixing the coal indirect liquefied oil products with hydrogen, performing hydrogenation refining under a hydrogenation catalyst, and performing fractionation on the hydrogenation refined oil products to obtain a fraction with a distillation range of 160-260 DEG C, and performing dewaxing on the fraction to obtain the coal-based light liquid paraffin.

[0004] However, during the long-term use of the hydrogenation catalyst, the high concentration of oxygen-containing organic matters in the liquid oil product will cause irreversible poisoning of the hydrogenation catalyst, affect the catalytic activity of the active metal components on the surface of the hydrogenation catalyst, and this will significantly shorten the catalytic life of the hydrogenation catalyst, and the hydrogenation catalyst in the hydrogenation reactor needs to be frequently replaced or regenerated, which greatly increases the production cost of the liquid paraffin, and at the same time, carbon deposition will occur during the catalysis, which affects the surface activity of the catalyst, and therefore, it is urgent to provide a solution to improve the above problems. SUMMARY

[0005] The present application aims to provide a hydrogenation catalyst, a preparation method thereof and application of the hydrogenation catalyst in separation of light liquid paraffin, which can effectively improve the catalytic stability and catalytic activity of the hydrogenation catalyst, and can effectively reduce the production cost of the liquid paraffin and improve the hydrogenation production efficiency.

[0006] In a first aspect, the present application provides a preparation method of a hydrogenation catalyst, which includes: mixing an organic ligand with nickel ions and zinc ions to prepare a composite MOF; calcining the composite MOF at a high temperature in a nitrogen atmosphere to obtain a catalytic precursor; immersing the catalytic precursor in a molybdenum-containing solution and separating to obtain a catalytic intermediate; and reducing the catalytic intermediate in a reducing gas at 300-450 DEG C to obtain the hydrogenation catalyst.

[0007] The preparation method provided by the application is advantageous in realizing molecular dispersion of nickel and zinc, and in promoting the conversion of the organic ligand into a carbon skeleton and improving the interaction between nickel, zinc and the carbon skeleton after nitrogenization calcination in a nitrogen atmosphere, thereby being advantageous in retaining the specific surface area of the catalytic precursor and establishing a mass transfer channel, and in promoting the loading of the catalyst on molybdenum through impregnation and effectively anchoring molybdenum ions on the surface carbon skeleton of the catalytic precursor to avoid aggregation in the high-temperature reduction process, and in reducing high-valence molybdenum to a low-valence state to endow the catalyst with an active center and effectively improve the carbon deposition resistance and poisoning resistance stability of the catalyst by using the carbon-nickel-zinc composite carrier.

[0008] Optionally, the organic ligand comprises one of 2-methylimidazole, 4-methylimidazole, imidazole and trimesic acid.

[0009] Optionally, the molybdenum-containing solution contains dissolved ammonium molybdate.

[0010] Optionally, the molar ratio of the organic ligand to the nickel ions is (5-10):(3-4).

[0011] Optionally, the molar ratio of the organic ligand to the zinc ions is (5-10):(1-2).

[0012] Optionally, the reducing gas comprises hydrogen.

[0013] Optionally, the organic ligand is mixed and coordinated with the nickel ions and the zinc ions at 30-50°C.

[0014] Optionally, the organic ligand is ultrasonically mixed with the nickel ions and the zinc ions.

[0015] Optionally, the organic ligand is mixed and coordinated with the nickel ions and the zinc ions, and then the composite MOF is obtained through centrifugal separation.

[0016] Optionally, the composite MOF is obtained through separation and drying after the mixed coordination.

[0017] Optionally, the particle size of the composite MOF is 0.1-1 microns.

[0018] Optionally, the composite MOF is calcined in a nitrogen atmosphere at 300-500°C.

[0019] Optionally, the composite MOF is calcined in a nitrogen atmosphere for 2-10 hours.

[0020] Optionally, the composite MOF is calcined in a nitrogen atmosphere at 1-5 MPa.

[0021] Optionally, the temperature is raised at a rate of 5℃ / min-20℃ / min under a nitrogen atmosphere.

[0022] Optionally, the catalytic precursor is obtained by high-temperature calcination under a nitrogen atmosphere, followed by cooling, washing, and drying.

[0023] Optionally, the catalytic precursor is immersed in a molybdenum-containing solution at 40℃-50℃.

[0024] Optionally, the mass ratio of the catalytic precursor to molybdenum in the molybdenum-containing solution is 1:(0.2-0.5).

[0025] Optionally, the solid-liquid ratio of the catalytic precursor in the molybdenum-containing solution is 0.05g / mL-0.08g / mL.

[0026] Optionally, the catalytic precursor is immersed in the molybdenum-containing solution for 12h-18h.

[0027] Optionally, the catalytic intermediate is reduced in a reducing gas for 2h-3h.

[0028] Optionally, the catalytic intermediate is reduced in a reducing gas at 2MPa-5MPa.

[0029] Optionally, the hydrogenation catalyst is obtained by cooling after reduction.

[0030] Optionally, the catalytic precursor and an active agent are mixed in the molybdenum-containing solution before immersion, and the active agent includes one of γ-aminopropyl triethoxysilane, γ-aminopropyl trimethoxysilane, and anilinemethyl triethoxysilane.

[0031] In a second aspect, the present application further provides a hydrogenation catalyst prepared by any of the above preparation methods.

[0032] In a third aspect, the present application further provides an application of the hydrogenation catalyst prepared by any of the above preparation methods in the separation of light liquid paraffin.

[0033] Optionally, the method comprises: catalytically hydrogenating coal indirect liquefaction oil in a hydrogenation reactor filled with the hydrogenation catalyst under a hydrogen atmosphere to obtain refined oil products; fractionating the refined oil products to obtain paraffin precursors with a distillation range of 180℃-260℃; and dewaxing the paraffin precursors to obtain light liquid paraffin.

[0034] Optionally, the catalytically hydrogenating is performed under a hydrogen atmosphere at 3MPa-8MPa.

[0035] Optionally, the catalytically hydrogenating is performed under a hydrogen atmosphere at 220℃-280℃.

[0036] Optionally, the hydrogenation reactor comprises one of a fixed bed reactor, a moving bed reactor, and a slurry bed reactor.

[0037] Optionally, the hydrogen to oil ratio is (100-1000):1 when the coal indirect liquefaction oil is catalytically hydrogenated.

[0038] Optionally, the refined oil product is fractionated in a fractionating column, the fractionating column has a theoretical plate number of 50-60, the fractionating column has a top temperature of 120-200 DEG C, a bottom temperature of 300-350 DEG C, and a pressure of 0.1-0.2 MPa, the fractionating column has at least two side lines, and at least one of the side lines has a distillation range of 180-260 DEG C.

[0039] The hydrogenation catalyst provided by the application has at least one of the following beneficial technical effects compared with the prior art: 1. The self-assembly mixed coordination forms a composite MOF, which is beneficial to realize the molecular-level dispersion of nickel and zinc, and after nitrogenization calcination in a nitrogen atmosphere, can promote the conversion of organic ligands into carbon skeletons and improve the interaction between nickel, zinc and the carbon skeletons, is beneficial to retain the specific surface area in the catalytic precursor and establish a mass transfer channel, and can effectively regulate the loading amount of molybdenum on the catalyst by impregnation to improve the catalytic activity; 2. The high-valence molybdenum is reduced to a low-valence state by reduction, which can endow the catalyst with active centers, and effectively improve the anti-coking and anti-poisoning stability of the catalyst by using the carbon-nickel-zinc composite carrier, which is beneficial to improve the catalytic stability. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. Unless otherwise defined, the technical terms or scientific terms used herein should have the usual meanings understood by those skilled in the art.

[0041] The present application provides a preparation method of a hydrogenation catalyst, comprising the following steps: S1. mixing and coordinating organic ligands with nickel ions and zinc ions to obtain a composite MOF; S2. high-temperature calcining the composite MOF in a nitrogen atmosphere to obtain a catalytic precursor; S3. impregnating the catalytic precursor in a molybdenum-containing solution and separating to obtain a catalytic intermediate; S4, reducing the catalytic intermediate in a reducing gas at 300-450°C to obtain the hydrogenation catalyst.

[0042] In fact, the complex MOF is obtained by self-assembly of the organic ligand and the metal ion in step S1, which is beneficial to improve the uniformity of dispersion of the metal ion in the complex MOF and the structural stability after assembly of the organic ligand, and avoid aggregation of the nickel ion and the zinc ion in the calcination process, and effectively enhance the interaction between the metal and the carrier through the geometric confinement space of the MOF.

[0043] In some embodiments, the organic ligand used in step S1 includes one of 2-methylimidazole, 4-methylimidazole, imidazole, and trimesic acid. In fact, by selecting different organic ligands in the construction of the MOF and the post-processing to obtain the hydrogenation catalyst, the structural stability and catalytic activity of the hydrogenation catalyst can be adjusted by different spatial structures and chemical compositions.

[0044] In some embodiments, the molar ratio of the organic ligand to the nickel ion and the zinc ion in step S1 is (5-10):(3-4):(1-2). In fact, the organic ligand can form a tetrahedral coordination structure with the zinc ion and chelate the nickel ion through the excess ligand in the mixed coordination process, which can effectively prevent the aggregation of free nickel ions. In addition, the excess setting of the organic ligand can effectively improve the uniformity and stability of the nickel ion and the zinc ion in the complex MOF.

[0045] In fact, by increasing the content of the nickel ion in the complex MOF in step S1, the catalytic precursor can form a porous structure when calcined in step S2, and can form a spinel structure with zinc calcination, which is beneficial to improve the retention amount of nickel in the catalytic precursor. Specifically, the organic ligand can be dissolved in advance to obtain a ligand solution, and then the nickel salt and the zinc salt can be added to the ligand solution for stirring and blending.

[0046] In some embodiments, the organic ligand is ultrasonically mixed with the nickel ion and the zinc ion at 30-50°C in step S1. In fact, by mixing at 30-50°C, the rapid coordination reaction between the organic ligand and the metal ion can be effectively driven, and the formation of large-size amorphous crystals can be avoided, which is beneficial to improve the consistency of the grain size of the complex crystal, and the local high pressure generated by the ultrasonic cavitation effect can further promote the assembly of the nickel-zinc bimetallic atomic-level dispersion.

[0047] In some embodiments, after the organic ligand is mixed with the nickel ions and zinc ions in step S1, the composite MOF is prepared by centrifugal separation and drying. In fact, the generated crystals after coordination can be accurately separated by centrifugal treatment, and the solvent in the composite MOF can be removed after drying treatment, thereby facilitating the maintenance of the pore structure during calcination and avoiding the introduction of impurities. Specifically, the centrifugal treatment can be performed at a speed of 500 rpm-5000 rpm, and the drying treatment can be performed in a vacuum drying oven at 60°C-90°C.

[0048] In some embodiments, after drying in step S1, the solid obtained by drying is ground, crushed, and sieved to obtain a composite MOF with a particle size range of 0.1 μm-1 μm. In fact, by controlling the particle size of the composite MOF, the specific surface area of the MOF can be controlled, and collapse can be avoided during calcination, thereby facilitating the maintenance of the surface morphology and specific surface area of the catalytic precursor.

[0049] In some embodiments, in step S2, the composite MOF is calcined in a nitrogen atmosphere at 300°C-500°C for 2h-10h. In fact, during calcination, the organic ligand is carbonized to form a nitrogen-doped carbon skeleton, which can effectively improve the structural stability of the carbon skeleton. At the same time, during calcination, the nickel ions and zinc ions can be anchored, and in addition, during calcination, nickel and zinc can be exposed on the surface of the skeleton to expose active sites, thereby facilitating catalytic hydrogenation.

[0050] In some embodiments, in step S2, the composite MOF is placed in an atmosphere furnace in advance, nitrogen gas is introduced for gas replacement at room temperature, and the nitrogen gas pressure is adjusted to 1 MPa-5 MPa. The atmosphere furnace is heated to 300°C-500°C at a rate of 5°C / min-20°C / min for heat preservation calcination. In fact, by heating in a nitrogen atmosphere, the composite MOF can be pre-carbonized during gradual heating, thereby avoiding the collapse of the composite MOF structure caused by direct high-temperature calcination.

[0051] In some embodiments, in step S2, after high-temperature calcination of the composite MOF in a nitrogen atmosphere, the catalytic precursor is prepared by cooling, washing, and drying. In fact, cooling after calcination facilitates the slow cooling and stress release of the catalytic precursor, and after washing and drying treatment, the debris shed during calcination can be removed, thereby facilitating the improvement of the purity of the catalytic precursor. Specifically, after high-temperature calcination, natural cooling or cooling at a rate of 1°C / min-5°C / min can be performed.

[0052] In some embodiments, the catalytic precursor is immersed in the molybdenum-containing solution at 40-50℃ for 12-18h in step S3. In fact, the molybdenum-containing solution can penetrate into the pores of the catalytic precursor during the immersion process, and hydrolysis occurs to generate molybdenum nano-deposits attached to the surface of the catalytic precursor. By controlling the immersion temperature and time, the molybdenum loading on the surface of the catalytic precursor can be regulated. Specifically, ammonium molybdate is dissolved in the molybdenum-containing solution, and the mass ratio of the catalytic precursor to molybdenum in the molybdenum-containing solution is 1:(0.2-0.5). In fact, molybdenum trioxide nano-deposits are generated during the hydrolysis of ammonium molybdate and attached to the pores of the catalytic precursor.

[0053] In some embodiments, the solid-liquid ratio in the mixed suspension is 0.05-0.08g / mL after the catalytic precursor is added to the molybdenum-containing solution for mixing in step S3. In addition, when the catalytic precursor is mixed in the molybdenum-containing solution, ultrasonic treatment can be applied intermittently, which can effectively break the small bubbles hidden in the catalytic precursor, thereby facilitating the full infiltration of the molybdenum-containing solution into the catalytic precursor and improving the uniformity of the surface molybdenum nano-deposits.

[0054] In some embodiments, the catalytic precursor and the active agent are added to the molybdenum-containing solution for mixing and then immersed in step S3. In fact, the addition of the active agent facilitates the stable suspension of the catalytic precursor in the molybdenum-containing solution, thereby avoiding the agglomeration and sedimentation of the catalytic precursor and improving the binding stability of the molybdenum nano-deposits generated by hydrolysis on the surface of the catalytic precursor. Specifically, the active agent used includes one of γ-aminopropyl triethoxysilane, γ-aminopropyl trimethoxysilane, and anilinomethyl triethoxysilane, and the mass ratio of the catalytic precursor to the active agent is 1:(0.1-0.2).

[0055] In some embodiments, the catalytic intermediate is treated in a reducing gas at 2-5MPa for 2-3h and then cooled to obtain the hydrogenation catalyst in step S4. In fact, the reducing gas used includes hydrogen. Specifically, by performing the reduction treatment, the molybdenum nano-deposits attached to the surface of the catalytic intermediate and the nickel in the framework are converted to an active state, thereby facilitating the hydrogenation catalysis, and the high-temperature treatment can fix the active molybdenum species on the surface of the catalytic intermediate.

[0056] The application also provides a use of the hydrogenation catalyst prepared by the above preparation method in the separation of light liquid paraffin, which comprises: preparing refined oil products by catalytic hydrogenation of coal indirect liquefied oil in a hydrogenation reactor filled with the hydrogenation catalyst under a hydrogen atmosphere; performing fractionation on the refined oil products to obtain paraffin precursors with a distillation range of 180-260℃; and dewaxing the paraffin precursors to obtain light liquid paraffin.

[0057] In fact, in the catalytic hydrogenation process, the oxygen-containing compounds and unsaturated hydrocarbons in the coal indirect liquefaction oil are hydrogenated to obtain hydrogenation products, and fractionation can separate naphtha, light liquid paraffin precursor, heavy liquid paraffin precursor, refined heavy diesel, refined tail oil and other products. Specifically, the product with a distillation range of 180-260°C is a light liquid paraffin precursor.

[0058] In some embodiments, the coal indirect liquefaction oil used can be a full fraction product of Fischer-Tropsch synthesis oil or a mixture of multiple fractions in the full fraction of Fischer-Tropsch synthesis oil. In addition, the light liquid paraffin obtained by dewaxing the light liquid paraffin precursor is a normal alkane with a carbon number of 10-13. The present application can obtain light liquid paraffin with high purity by using coal indirect liquefaction oil for hydrogenation fractionation and dewaxing treatment, which is beneficial to the industrial application of light liquid paraffin.

[0059] In some embodiments, the coal indirect liquefaction oil is subjected to catalytic hydrogenation under a hydrogen atmosphere of 3-8 MPa and 220-280°C. In fact, in the catalytic hydrogenation process, hydrogen molecules are dissociated into hydrogen active species at the interface of active molybdenum and active nickel, and at the same time, oxygen-containing compounds and unsaturated hydrocarbons are adsorbed on the active interface to promote C-O cleavage and hydrogenation to obtain hydrogenation products.

[0060] In some embodiments, the hydrogenation catalyst is pre-loaded in the hydrogenation reactor. Specifically, the hydrogenation reactor used includes one of a fixed bed reactor, a moving bed reactor, and a slurry bed reactor. In addition, the hydrogen to oil ratio is (100-1000):1 when the coal liquefaction oil is subjected to catalytic hydrogenation. In fact, the hydrogenation catalyst can be loaded in the hydrogenation reactor, and hydrogen and coal indirect liquefaction oil can be mixed and introduced into the top of the hydrogenation reactor, and reacted under the action of gas pressure.

[0061] In some embodiments, after the hydrogenation to obtain refined oil products, fractionation is carried out in a fractionation column, and the theoretical plate number of the fractionation column is 50-60. In the fractionation process, the refined oil products are introduced from the bottom of the fractionation column, and the overhead temperature of the fractionation column is controlled at 120-200°C, the bottom temperature is controlled at 300-350°C, the pressure in the fractionation column is controlled at 0.1-0.2 MPa, and in addition, the fractionation column has at least two side lines, at least one of which has a distillation range of 180-260°C, so that the light liquid paraffin precursor can be obtained by fractionation.

[0062] In some embodiments, after obtaining the light liquid paraffin precursor, the normal paraffin is separated by using an adsorbent, and then the light liquid paraffin is obtained by using a desorption agent for desorption. Specifically, the adsorbent used can be a dewaxing adsorbent commonly used in the art, such as a molecular sieve, which can selectively adsorb normal paraffin from the precursor by adsorption on the molecular sieve at 300-350°C, and then the light liquid paraffin is obtained by using superheated steam at 360-380°C for desorption treatment.

[0063] Embodiment 1 The embodiment 1 provides a preparation method of a hydrogenation catalyst, comprising the following steps: S1, stirring and dissolving 2-methylimidazole in ethanol to obtain a 2-methylimidazole solution with a concentration of 0.5 g / mL, mixing the 2-methylimidazole solution with a saturated aqueous solution of nickel chloride and a saturated aqueous solution of zinc chloride to obtain a coordination mixed solution, and adjusting the molar ratio of 2-methylimidazole, nickel ions and zinc ions to 6:3:1; placing the coordination mixed solution in a 40°C water bath environment and applying 2kw ultrasonic treatment for 15 min, then standing for 2h reaction, then centrifuging to obtain a precipitate at a speed of 3000 rpm, and then drying the precipitate in a 80°C vacuum drying oven to constant weight to obtain a composite MOF; S2, transferring the composite MOF to a gas furnace, purging twice with nitrogen, adjusting the nitrogen pressure in the gas furnace to 3MPa, gradually increasing the temperature of the gas furnace from room temperature to 400°C at a rate of 10°C / min, and maintaining the temperature for calcination for 5h, then cooling the furnace to room temperature, ultrasonic cleaning in anhydrous ethanol, and drying to constant weight in a 80°C vacuum drying oven to obtain a catalytic precursor; S3, adding the catalytic precursor to an aqueous ammonium molybdate solution at a solid-liquid ratio of 0.06g / mL to obtain a mixed suspension, adjusting the mass ratio of the catalytic precursor to molybdenum in the mixed suspension to 1:0.3, and then placing the mixed suspension in a 45°C water bath environment and applying 2kw ultrasonic treatment intermittently (10 min each time, with an interval of 20 min), then immersing the mixed suspension for 15h (a total of 30 times of ultrasonic treatment), then centrifuging, rinsing with anhydrous ethanol, and drying to constant weight in a 50°C vacuum drying oven to obtain a catalytic intermediate; S4, placing the catalytic intermediate in a gas furnace, purging the gas furnace with hydrogen, adjusting the hydrogen pressure in the gas furnace to 3MPa, gradually increasing the temperature of the gas furnace to 400°C at a rate of 5°C / min, maintaining the temperature for 3h, and then cooling the furnace to room temperature to obtain a hydrogenation catalyst.

[0064] Embodiment 2 The embodiment 2 provides a preparation method of a hydrogenation catalyst, which is different from the embodiment 1 in that in step S3, the catalytic precursor KH550 is mixed into the ammonium molybdate aqueous solution at a mass ratio of 1:0.15 to obtain a mixed suspension, and the solid-liquid ratio of the catalytic precursor to the ammonium molybdate aqueous solution in the mixed suspension is 0.06 g / mL.

[0065] Comparative example 1 The comparative example 1 provides a preparation method of a hydrogenation catalyst, which is different from the embodiment 1 in that in step S1, the mole ratio of 2-methylimidazole, nickel ions and zinc ions in the coordination mixed solution is adjusted to 6:1:3.

[0066] Comparative example 2 The comparative example 2 provides a preparation method of a hydrogenation catalyst, which is different from the embodiment 1 in that in step S1, the 2-methylimidazole solution is mixed with the saturated aqueous solution of nickel chloride, and the mole ratio of 2-methylimidazole to nickel ions is adjusted to 6:4.

[0067] Comparative example 3 The comparative example 3 provides a preparation method of a hydrogenation catalyst, which is different from the embodiment 1 in that in step S1, the 2-methylimidazole solution is mixed with the saturated aqueous solution of zinc chloride, and the mole ratio of 2-methylimidazole to zinc ions is adjusted to 6:4.

[0068] Comparative example 4 The comparative example 4 provides a preparation method of a hydrogenation catalyst, which is different from the embodiment 1 in that step S3 is not performed, and the catalytic precursor prepared in step S2 is directly subjected to step S4.

[0069] Comparative example 5 The comparative example 5 provides a preparation method of a hydrogenation catalyst, which is different from the embodiment 1 in that in step S1, the 2-methylimidazole solution is mixed with the saturated aqueous solution of ruthenium chloride and the saturated aqueous solution of zinc chloride to prepare a coordination mixed solution, and the mole ratio of 2-methylimidazole, ruthenium ions and zinc ions is adjusted to 6:3:1.

[0070] Comparative example 6 The comparative example 6 provides a preparation method of a hydrogenation catalyst, which is different from the embodiment 1 in that in step S1, the 2-methylimidazole solution is mixed with the saturated aqueous solution of cobalt chloride and the saturated aqueous solution of zinc chloride to prepare a coordination mixed solution, and the mole ratio of 2-methylimidazole, cobalt ions and zinc ions is adjusted to 6:3:1.

[0071] Application examples 1-8 The application examples 1-8 (corresponding to the embodiment examples 1-2 and the comparative examples 1-6, respectively) each provide a light liquid paraffin separation method, which comprises: The hydrogenation catalyst prepared in Example 1 to Example 2, Comparative Example 1 to Comparative Example 6 was respectively filled into a fixed bed reactor; hydrogen was introduced into the reactor and replaced by gas, and then the hydrogen pressure was adjusted to 5 MPa; after the temperature of the reactor was adjusted to be constant at 260℃, the coal indirect liquefaction oil was mixed with hydrogen and introduced from the top of the reactor, and the hydrogen to oil ratio was controlled to be 500:1; the static oil product was collected from the bottom of the reactor after catalytic hydrogenation; The static oil product was introduced into a fractionating column for atmospheric fractionation, the column top temperature was controlled to be 180℃±5℃, the column bottom temperature was controlled to be 320℃±5℃, and the pressure was controlled to be 0.15 MPa±0.01 MPa; the light liquid paraffin precursor was collected from a side line of the fractionating column in a 220℃±5℃ distillation range; the light liquid paraffin precursor was introduced into an adsorption bed (filled with ADS-34 dewaxing molecular sieve), and the light liquid paraffin was obtained by dewaxing adsorption at 320℃ and desorption using superheated water vapor at 360℃.

[0072] Performance detection The light liquid paraffin content in the coal indirect liquefaction oil was detected by the method described in NB / SH / T0417-2013, and the n-alkane content in the light liquid paraffin was detected, and the results are shown in Table 1; the separation method in Application Example 1-8 was repeatedly applied, and when the n-alkane content decreased by more than or equal to 5% compared with the first separation, it was considered that the hydrogenation catalyst reached the catalytic limit; the change of the catalytic use limit of the hydrogenation catalyst in Application Example 1-8 was calculated, and the results are shown in Table 1.

[0073] Table 1: Detection results in Application Example 1-8 No. n-alkane content in light liquid paraffin / wt% Catalytic limit change / % Application Example 1 93.51 100.00 Application Example 2 94.62 112.58 Application Example 3 84.48 93.52 Application Example 4 81.17 86.24 Application Example 5 72.35 82.67 Application Example 6 66.98 79.82 Application Example 7 71.65 84.81 Application Example 8 73.96 85.29 In combination with Example 1 and Example 2, the addition of a surfactant during the loading of molybdenum is beneficial to improve the loading of molybdenum on the catalytic precursor, and thus the catalytic activity of the hydrogenation catalyst can be improved during the catalysis process; in combination with Example 1 and Comparative Example 1, when the nickel content in the skeleton of the catalytic precursor is reduced and the zinc content is increased, it will lead to a decrease in the catalytic activity of the hydrogenation catalyst, because the active zinc in the skeleton can also play a role in hydrogen cracking during the catalysis process, and the stability of the catalyst is reduced; in combination with Example 1 and Comparative Example 2-3, a large amount of nickel in the skeleton of the catalytic precursor can stabilize the catalytic activity, and it can be explained that the role of zinc in the skeleton of the catalytic precursor is biased towards assisting to improve the catalytic activity and catalytic stability; in combination with Example 1 and Comparative Example 4, the unloading of molybdenum in the hydrogenation catalyst has a significant impact on the decrease in catalytic activity; in combination with Example 1 and Comparative Example 5-6, the use of other metal ions such as ruthenium and cobalt to replace nickel in the catalytic precursor has no obvious promoting effect on the catalytic activity and catalytic stability of the catalyst.

[0074] While the embodiments of the application have been illustrated and described in detail, it will be readily apparent to those skilled in the art that various modifications and changes can be made to the embodiments without departing from the scope of the application as described in the claims. It is therefore intended that the application not be limited to the exact embodiments described herein, but that the application can also include all such modifications and changes as fall within the scope of the claimed application. Moreover, the application illustratively described herein suitably can be practiced in the absence of any element or step which is not specifically disclosed herein.

Claims

1. A process for the preparation of a hydrogenation catalyst, characterized in that The method comprises the following steps: The organic ligand is mixed with nickel ions and zinc ions to obtain a composite MOF; the composite MOF is calcined in a nitrogen atmosphere at 300-500 DEG C to obtain a catalytic precursor; the catalytic precursor is immersed in a molybdenum-containing solution and separated to obtain a catalytic intermediate; and the catalytic intermediate is reduced in a reducing gas at 300-450 DEG C to obtain a hydrogenation catalyst.

2. The production method according to claim 1, characterized by, The organic ligand comprises one of 2-methylimidazole, 4-methylimidazole, imidazole and trimesic acid; the molybdenum-containing solution contains ammonium molybdate; the molar ratio of the organic ligand to the nickel ions is (5-10):(3-4); the molar ratio of the organic ligand to the zinc ions is (5-10):(1-2); and the reducing gas comprises hydrogen.

3. The preparation method according to claim 1, characterized in that, The organic ligand is mixed with nickel ions and zinc ions at 30-50 DEG C; the organic ligand is mixed with nickel ions and zinc ions under ultrasonic mixing; the composite MOF is obtained by centrifugal separation after the organic ligand is mixed with nickel ions and zinc ions; the composite MOF is obtained by separation and drying after the organic ligand is mixed with nickel ions and zinc ions; and the particle size of the composite MOF is 0.1-1 microns.

4. The preparation method according to claim 1, characterized in that, The composite MOF is calcined in a nitrogen atmosphere for 2-10 hours; the composite MOF is calcined in a nitrogen atmosphere at 1-5 MPa; the temperature is raised at a rate of 5-20 DEG C / min in the nitrogen atmosphere; and the catalytic precursor is obtained by cooling, washing and drying after the composite MOF is calcined in a nitrogen atmosphere at 300-500 DEG C.

5. The preparation method according to claim 1, characterized in that, The catalytic precursor is immersed in a molybdenum-containing solution at 40-50 DEG C; the mass ratio of the catalytic precursor to molybdenum in the molybdenum-containing solution is 1:(0.2-0.5); the solid-liquid ratio of the catalytic precursor in the molybdenum-containing solution is 0.05-0.08 g / mL; and the catalytic precursor is immersed in the molybdenum-containing solution for 12-18 hours.

6. The method of claim 1, wherein, The catalytic intermediate is reduced in a reducing gas for 2-3 hours; the catalytic intermediate is reduced in a reducing gas at 2-5 MPa; the hydrogenation catalyst is obtained by cooling after reduction; and the catalytic precursor and an active agent are mixed in the molybdenum-containing solution before immersion, wherein the active agent comprises one of gamma-aminopropyltriethoxysilane, gamma-aminopropyltrimethoxysilane and anilinomethyltriethoxysilane.

7. A hydrogenation catalyst prepared by the preparation method in any one of claims 1 to 6.

8. Application of a hydrogenation catalyst prepared by the preparation method in any one of claims 1 to 6 in separation of light liquid paraffin.

9. Use according to claim 8, characterized in that, The method comprises the following steps: Coal indirect liquefied oil is catalytically hydrogenated in a hydrogen atmosphere in a hydrogenation reactor filled with a hydrogenation catalyst to obtain refined oil products; the refined oil products are fractionated to obtain paraffin precursors with a distillation range of 180-260 DEG C; and the paraffin precursors are dewaxed to obtain light liquid paraffin.

10. Use according to claim 9, characterized in that, Catalytic hydrogenation of the coal indirect liquefaction oil is carried out under a hydrogen atmosphere of 3-8 MPa; and / or, catalytic hydrogenation of the coal indirect liquefaction oil is carried out under a hydrogen atmosphere of 220-280℃; and / or, the hydrogenation reactor comprises one of a fixed bed reactor, a moving bed reactor, and a slurry bed reactor; and / or, the hydrogen to oil ratio is (100-1000):1 during catalytic hydrogenation of the coal indirect liquefaction oil; and / or, refined oil products are fractionated in a fractionating column, the fractionating column has a theoretical plate number of 50-60, the fractionating column has a top temperature of 120-200℃, a bottom temperature of 300-350℃, and a pressure of 0.1-0.2 MPa, the fractionating column has at least two side lines, and at least one of the side lines has a distillation range of 180-260℃.