High-stability pre-reduced hpPO cyclic methanol hydrogenation catalyst, preparation method and application thereof

Abstract

The application relates to the field of catalyst preparation, and discloses a high-stability pre-reduction type HPPO cyclic methanol hydrogenation catalyst as well as a preparation method and application thereof. The catalyst comprises a main catalyst and an auxiliary catalyst which respectively contain carriers and active components. On the basis of the total amount of the hydrogenation catalyst, the content of the main catalyst is 77-95% by weight in terms of oxides, and the content of the auxiliary catalyst is 5-23% by weight in terms of oxides. The active component in the main catalyst comprises Ni and / or Co, and the active component in the auxiliary catalyst comprises Mo and / or Mn. On the basis of the total amount of the hydrogenation catalyst, the content of Ni and / or Co is 25-65% by weight in terms of oxides, and the content of Mo and / or Mn is 0.05-2.4% by weight in terms of oxides. The number of active centers of the hydrogenation catalyst after re-reduction treatment is 0.08-0.48 mmol of hydrogen gas per gram of catalyst. The catalyst has good reactivation performance, many active centers, good stability and a good industrial application prospect.

Description

Technical Field

[0001] The present invention relates to the field of catalyst preparation, and in particular to a high-stability pre-reduction HPPO circulating methanol hydrogenation catalyst, a preparation method and application thereof. Background Art

[0002] The HPPO process uses hydrogen peroxide to epoxidize propylene to produce propylene oxide. The reaction of propylene with hydrogen peroxide occurs in a methanol solvent. Some byproducts generated in the HPPO process, as well as recycled methanol, react with hydrogen peroxide to form compounds such as formaldehyde, acetaldehyde, propylene glycol, hydroxyacetone, formic acid, acetic acid, methyl formate, methyl acetate, and acetals. These compounds accumulate in the recycled methanol and are difficult to separate by distillation, directly affecting the purity of the PO product. Catalytic hydrogenation can remove most of these byproduct compounds. Catalysts using metals such as Pd, Pt, Rh, Ru, Ir, Os, and Ni are used as catalysts, and supports are activated carbon or porous metal oxides such as activated carbon, Al2O3, SiO2, zeolites, aluminosilicates, TiO2, and ZrO2.

[0003] Nickel catalysts are widely used in hydrogenation reactions due to their relatively low price and high hydrogenation activity. Applications include oil hydrogenation, vegetable oil hydrogenation, CO hydrogenation, olefin hydrogenation, alkyne hydrogenation, aromatics hydrogenation, nitrobenzene hydrogenation, and natural chlorophyll hydrogenation. In the HPPO cycle methanol hydrogenation process, the catalyst requires high hydrogenation performance at low temperatures (e.g., below 120°C).

[0004] Catalysis is a key core technology in the HPPO cycle for methanol hydrogenation. The metal components of the catalyst are typically prepared as oxides, requiring reduction treatment to render them catalytically active. Properly selecting catalyst reduction pretreatment conditions can enhance catalyst activity in the reaction.

[0005] Catalyst reduction can be achieved by either pre-reduction outside the reactor or reduction inside the reactor. Generally speaking, catalyst reduction in a reaction unit is difficult to operate. Improper operation will cause temperature fluctuations, which will lead to catalyst sintering and cause immeasurable economic losses. Catalyst pre-reduction technology has many advantages. In addition to improving the utilization rate of reducing agents, reducing the amount of reducing agents, reducing start-up costs, and shortening the start-up cycle, it can ultimately increase the economic benefits of the enterprise. The pre-reduced catalyst is loaded into the reactor and then reactivated at low temperature before use. It is especially suitable for situations where the reduction temperature is significantly higher than the subsequent reaction temperature, and the reactor does not need to undergo special processing due to the reduction reaction. The reaction temperature of HPPO circulating methanol hydrogenation is relatively low, and the reactor does not need to undergo special processing due to the reduction reaction. In order to reduce investment, the industry is in urgent need of a pre-reduction method for HPPO circulating methanol hydrogenation catalysts.

[0006] Different reduction and passivation treatments for the same catalyst have different effects on the activity and selectivity of the reaction. Different catalysts are often treated with different reduction and passivation treatments to achieve optimal activity and selectivity. Drawbacks of the prior art include long catalyst reduction times and high hydrogen consumption, resulting in long catalyst processing cycles and high costs, which affect the efficiency of catalyst reduction and passivation. Known passivation methods require long passivation times and produce uneven catalyst passivation.

[0007] During the reduction process, large catalyst particles can experience uneven reduction not only across different catalyst layers but also within a single catalyst particle. Furthermore, if the intense heat released during passivation is not promptly removed, it can exacerbate the degree of passivation, leading to runaway temperatures and metal sintering in severe cases. From the perspective of mass transfer, heat transfer, and reaction, fine powders exhibit significantly higher mass and heat transfer rates than large particles, improving the diffusion conditions of the reaction. This not only reduces the adverse effects of water on the reduction of metal catalysts during the reduction process, but also allows for timely heat removal during the passivation process, making the degree of passivation more controllable. Summary of the Invention

[0008] The purpose of the present invention is to overcome the defects of the existing technology that the catalytic activity of the pre-reduction catalyst is low and the stability needs to be further improved, and to provide a highly stable pre-reduction HPPO cyclic methanol hydrogenation catalyst and its preparation method and application. The catalyst has good reactivation performance, multiple active centers, good stability, and has good industrial application prospects.

[0009] During the research process, the inventors of the present invention further discovered that in the preparation of the pre-reduction catalyst, a main catalyst precursor containing an active component is first prepared, then reduced and passivated, and then formed. In particular, a specific co-catalyst is introduced during the forming process, which can change the physical properties of the catalyst, improve the activity and stability of the catalyst, and exhibit excellent methanol purification performance. The reason may be that the co-catalyst introduced during the forming process is at a certain distance from the active component introduced previously on the carrier, so that during the circulating methanol purification process, on the one hand, carbon deposition occurs on part of the co-catalyst, thereby avoiding carbon deposition on the active component, thereby maintaining the activity of the active component, and further improving the activity and stability of the catalyst. On the other hand, the remaining co-catalyst will undergo non-hydrogenation purification reaction, thereby promoting the methanol purification effect.

[0010] To achieve the above objectives, the present invention provides a highly stable pre-reduction HPPO circulating methanol hydrogenation catalyst in a first aspect. The hydrogenation catalyst comprises a main catalyst and a co-catalyst, each containing a carrier and an active component. Based on the total amount of the hydrogenation catalyst, the content of the main catalyst is 77-95% by weight, and the content of the co-catalyst is 5-23% by weight, calculated as oxides. The active components in the main catalyst include Ni and / or Co, and the active components in the co-catalyst include Mo and / or Mn. Based on the total amount of the hydrogenation catalyst, the content of Ni and / or Co is 25-65% by weight, and the content of Mo and / or Mn is 0.05-2.4% by weight, calculated as oxides.

[0011] The number of active centers of the hydrogenation catalyst after re-reduction treatment is 0.08-0.48 mmol hydrogen / g catalyst. The re-reduction treatment conditions include: temperature of 200° C., time of 2 hours, re-reduction atmosphere of hydrogen and argon with a hydrogen concentration of 10% by volume, and a gas-to-agent ratio of 15000.

[0012] A second aspect of the present invention provides a method for preparing a highly stable pre-reduction HPPO circulating methanol hydrogenation catalyst, the method comprising:

[0013] (1) preparing a main catalyst precursor from a carrier precursor and an active component source containing Ni and / or Co, drying and / or calcining the main catalyst precursor and optionally pulverizing the main catalyst precursor to obtain a solid product with a particle size of less than 2000 μm;

[0014] (2) subjecting the solid product to reduction treatment and passivation treatment in sequence, wherein the reduction treatment is carried out in the presence of a hydrogen-containing gas; the passivation treatment is carried out in the presence of a passivating agent, and the passivation conditions include: a passivation temperature not exceeding 140° C.;

[0015] (3) mixing the product obtained in step (2) with a co-catalyst and an optional shaping agent and / or an optional lubricant to form a mixture; the co-catalyst comprises a carrier and an active component, and the active component in the co-catalyst comprises Mo and / or Mn;

[0016] The amounts of the carrier precursor, the active component source, the co-catalyst, the molding agent and the lubricant are such that, in the prepared catalyst, based on the total amount of the hydrogenation catalyst, the content of the main catalyst is 77-95% by weight, the content of the co-catalyst is 5-23% by weight, and the total content of the molding agent and / or lubricant is 0-12% by weight, calculated as oxides; and the content of Ni and / or Co is 25-65% by weight, and the content of Mo and / or Mn is 0.05-2.4% by weight.

[0017] The third aspect of the present invention provides a high-stability pre-reduction HPPO circulating methanol hydrogenation catalyst prepared by the method described in the second aspect.

[0018] The fourth aspect of the present invention provides use of the high-stability pre-reduction HPPO cycle methanol hydrogenation catalyst described in the first aspect or the third aspect in the purification of HPPO cycle methanol.

[0019] The catalyst provided by the present invention is a pre-reduction catalyst with good reactivation performance, multiple active centers, excellent stability, good industrial application prospects, and good circulating methanol hydrogenation performance. It is particularly suitable for HPPO circulating methanol purification.

[0020] The catalyst preparation method provided by the present invention achieves rapid and sufficient reduction, gentle passivation, and high efficiency. After reshaping, the resulting catalyst is highly uniform, easily regenerated, and has numerous active centers. Furthermore, the catalyst's stability is significantly improved. In the preferred reduction and passivation treatment schemes of the present invention, the reduction and passivation effects are even better, and the resulting catalyst exhibits enhanced reactivity and stability. DETAILED DESCRIPTION

[0021] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0022] In the present invention, the gas-to-agent ratio refers to the ratio of the volume of gas passing through the catalyst bed per hour to the volume of the catalyst. In the reduction process (or re-reduction process), the gas in the gas-to-agent ratio refers to the reducing gas (i.e., hydrogen-containing gas). In the gas passivation process, the gas in the gas-to-agent ratio refers to the passivating gas (i.e., oxygen-containing passivating gas, also called oxidizing gas).

[0023] In the present invention, the "high stability" in the high-stability pre-reduction HPPO cyclic methanol hydrogenation catalyst means that the catalyst has good stability and does not limit the composition and structure of the catalyst.

[0024] A first aspect of the present invention provides a highly stable pre-reduction HPPO circulating methanol hydrogenation catalyst, the hydrogenation catalyst comprising a main catalyst and a co-catalyst, each comprising a carrier and an active component. The main catalyst comprises 77-95% by weight, and the co-catalyst comprises 5-23% by weight, calculated as oxides, based on the total amount of the hydrogenation catalyst. The active components in the main catalyst comprise Ni and / or Co, and the active components in the co-catalyst comprise Mo and / or Mn. The Ni and / or Co content, calculated as oxides, comprises 25-65% by weight, and the Mo and / or Mn content comprises 0.05-2.4% by weight, based on the total amount of the hydrogenation catalyst.

[0025] The number of active centers of the hydrogenation catalyst after re-reduction treatment is 0.08-0.48 mmol hydrogen / g catalyst. The re-reduction treatment conditions include: temperature of 200° C., time of 2 hours, re-reduction atmosphere of hydrogen and argon with a hydrogen concentration of 10% by volume, and a gas-to-agent ratio of 15000.

[0026] In the present invention, the number of active centers is obtained by H2 temperature-programmed desorption (H2-TPD) testing on an Autochem 2950 fully automatic high-pressure chemical adsorption instrument produced by Micromeritics, USA. The testing method is as follows: 0.2000g of a 40-60 mesh sample is weighed and first subjected to reduction activation under the following reduction conditions: an H2-Ar mixed gas with a hydrogen content of 10% by volume and a mixed gas flow rate of 50mL / min, heated to 200°C at a heating rate of 10°C / min, and reduced for 2h. The reduced catalyst is cooled in an H2-Ar mixed gas with a hydrogen content of 10% by volume. After the temperature drops to 55°C, it is switched to Ar gas for purging at an Ar flow rate of 20mL / min until the baseline stabilizes, and then the H2-TPD experiment is performed. The experimental conditions and procedures of H2-TPD were as follows: carrier gas was Ar, carrier gas flow rate was 20 mL / min, heating rate was 10 °C / min, final temperature was 400 °C, thermal conductivity detector (TCD) was used to detect the signal, and TPD curve was obtained.

[0027] In the present invention, preferably, the active component is nickel.

[0028] Those skilled in the art can select the carriers of the main catalyst and the co-catalyst according to actual needs. Preferably, the carrier of the main catalyst is selected from at least one of aluminum oxide, silicon oxide, zirconium oxide and titanium oxide.

[0029] Preferably, the carrier in the co-catalyst is selected from at least one of Group IIA metal oxides, Group VIB metal oxides, Group VIIB metal oxides, Group IIB metal oxides, Group IIIA metal oxides and activated carbon, and more preferably selected from at least one of magnesium oxide, zinc oxide, calcium oxide, aluminum oxide and activated carbon.

[0030] According to a preferred embodiment of the present invention, the co-catalyst further comprises at least one of precious metals, more preferably at least one of Pt, Pd, Ir, Rh, Ru, and Os. Under this preferred embodiment, the catalyst has better performance in purifying recycled methanol.

[0031] Preferably, the content of the noble metal as an element is 0.005-0.05 wt % based on the total amount of the hydrogenation catalyst and calculated as oxide.

[0032] The catalyst of the present invention may also contain other auxiliary elements, such as lanthanide elements, etc., which can be freely selected by those skilled in the art according to actual needs.

[0033] According to the present invention, preferably, the hydrogenation catalyst further comprises a molding agent and / or a lubricant. Based on the total amount of the hydrogenation catalyst, calculated as oxide, the content of the main catalyst is 77-93 weight %, the content of the co-catalyst is 5-11 weight %, and the total content of the molding agent and / or lubricant is 2-12 weight %.

[0034] The present invention does not limit the forming agent and lubricant, and those skilled in the art can freely select according to actual needs. Preferably, the forming agent comprises at least one of methylcellulose, sesbania powder, cement and water. Preferably, the lubricant comprises at least one of graphite, paraffin oil, ester lubricant, talc, stearic acid and palmitic acid and metal or alkali metal salts of these acids.

[0035] In the present invention, the hydrogenation catalyst is in granular form. Preferably, the particle size of the hydrogenation catalyst is 2-8 mm.

[0036] In the present invention, the particle size refers to the distance between the two points on the particle that are farthest apart. For example, when the particle is microspherical, the particle size refers to the diameter of the microsphere; when the particle is long strip, the particle size refers to the length of the strip; when the particle is a cube, the particle size refers to the length of the body center diagonal.

[0037] In the present invention, the catalyst is a pre-reduced catalyst. Preferably, the number of active centers of the hydrogenation catalyst after re-reduction treatment is 0.15-0.45 mmol hydrogen / g catalyst.

[0038] Preferably, as characterized by TPR, the temperature corresponding to the peak of the low-temperature reduction peak with the largest area in the TPR curve of the catalyst is 125-245° C. The catalyst provided by the present invention has good regeneration ability and can be restored to activity by simply reducing it under relatively low reduction treatment conditions, and has a large number of active centers.

[0039] In the present invention, the TPR (temperature-programmed reduction) characterization was performed using an Autochem 2950 fully automatic high-pressure chemical adsorption instrument manufactured by Micromeritics, USA. The test conditions were as follows: a 0.20 g sample was first heated to 120°C for dehydration under a 50 mL / min Ar flow at a heating rate of 10°C / min for 1 hour. After the temperature dropped to 50°C, a TPR experiment was performed. The TPR experimental conditions and procedure were as follows: the reducing gas was an H2-Ar mixture containing 10% hydrogen by volume, the reducing gas flow rate was 50 mL / min, and the temperature was raised to 900°C at a heating rate of 10°C / min. During the heating process, the signal was detected by a thermal conductivity detector (TCD) to obtain a TPR spectrum curve. The temperature corresponding to the peak of the low-temperature reduction peak with the largest area in the TPR spectrum curve was used as an indicator to evaluate the regeneration performance of the passivated catalyst. The lower the temperature corresponding to the peak of the low-temperature reduction peak with the largest area, the easier the catalyst is to regenerate.

[0040] The high-stability pre-reduction HPPO circulating methanol hydrogenation catalyst provided by the present invention has specific physical properties, a large number of active centers, significantly improved stability, and exhibits excellent circulating methanol purification performance, especially hydrogenation performance.

[0041] A second aspect of the present invention provides a method for preparing a highly stable pre-reduction HPPO circulating methanol hydrogenation catalyst, the method comprising:

[0042] (1) preparing a main catalyst precursor from a carrier precursor and an active component source containing Ni and / or Co, drying and / or calcining the main catalyst precursor and optionally pulverizing the main catalyst precursor to obtain a solid product (also referred to as a catalyst precursor) having a particle size of less than 2000 μm;

[0043] (2) subjecting the solid product to reduction treatment and passivation treatment in sequence, wherein the reduction treatment is carried out in the presence of a hydrogen-containing gas; the passivation treatment is carried out in the presence of a passivating agent, and the passivation conditions include: a passivation temperature not exceeding 140° C.;

[0044] (3) mixing the product obtained in step (2) with a co-catalyst and an optional shaping agent and / or an optional lubricant to form a mixture; the co-catalyst comprises a carrier and an active component, and the active component in the co-catalyst comprises Mo and / or Mn;

[0045] The amounts of the carrier precursor, the active component source, the promoter and the forming agent and the lubricant are such that, in the catalyst obtained, the content of the main catalyst is 77-95% by weight, the content of the promoter is 5-23% by weight, the total content of the forming agent and / or the lubricant is 0-12% by weight, the content of Ni and / or Co is 25-65% by weight and the content of Mo and / or Mn is 0.05-2.4% by weight, all based on the total amount of the hydrogenation catalyst in terms of oxides.

[0046] The inventors have found that, in the specific preparation method described above, on the one hand, by introducing the promoter in the shaping, the reactivity and stability of the obtained catalyst can be improved; and on the other hand, by reducing and passivating the solid product of a specific particle size and then shaping, the solid product can be fully reduced, the adverse effects of water on the metal can be reduced, and thus the reactivity and stability of the obtained catalyst can be improved as a whole.

[0047] In the present application, it can be understood that the optional types of the active component containing Ni and / or Co and the promoter correspond to the same as the first aspect described above, and thus will not be described again here.

[0048] According to the present application, the drying can be any one of ordinary drying, microwave drying, spray drying and flash drying, and is preferably spray drying.

[0049] According to a preferred embodiment of the present application, the drying process comprises drying the main catalyst precursor at 80-180°C for 2-24 hours.

[0050] According to another preferred embodiment of the present application, the drying process comprises beating the main catalyst precursor to obtain a slurry with a solid content of 15-50% by weight, preferably 30-40% by weight, and then spray drying the slurry. Generally, a particle is obtained after spray drying.

[0051] In the present application, the beating is preferably carried out under stirring, and the stirring time is preferably 1-6 hours. It can be understood that a solvent is introduced during the beating, and the solvent is preferably water, and the slurry is a water slurry. Preferably, an alcohol is also added during the beating; the alcohol is preferably ethanol, and the amount of the alcohol added is preferably 0.5-3% by weight.

[0052] More preferably, the spray drying conditions include: an atomization pressure of 1-5 MPa, an inlet temperature of 250-400°C, an outlet temperature of 80-160°C, and an atomization drying time of 2-5 seconds. It is understood that the spray drying is carried out in a spray dryer, and the inlet temperature and outlet temperature are the inlet temperature and outlet temperature of the spray dryer, respectively.

[0053] In the present invention, the main catalyst precursor can be dried first and then calcined, or the main catalyst precursor can be directly calcined. Preferably, the calcination conditions include: a calcination temperature of 300-500°C, more preferably 300-400°C, and a calcination time of 2-10 hours.

[0054] In the present invention, it is understood that if drying can result in a solid product having a desired particle size, then pulverization is unnecessary. If drying cannot result in a solid product having a desired particle size, pulverization is necessary to obtain a solid product having the desired particle size. The present invention does not limit the method of pulverization; for example, the desired particle size can be achieved by grinding.

[0055] Preferably, the particle size of the solid product is 5-1600 μm, more preferably 10-1000 μm, and even more preferably 50-800 μm. Under the preferred embodiment, it is more conducive to full reduction and passivation, and has better uniformity and higher efficiency.

[0056] In the present invention, there are no restrictions on the carrier precursor, as long as the carrier in the main catalyst precursor can be prepared. The optional range of the carrier in the main catalyst precursor is the same as that corresponding to the first aspect. Preferably, the carrier precursor is selected from at least one of silica sol, water glass, aluminum sol, sodium metaaluminate, aluminum nitrate, aluminum chloride, zinc nitrate, zirconium nitrate, and tetrabutyl titanate. Those skilled in the art can freely select the concentration of silicon or aluminum in the silica sol, water glass, or aluminum sol, and the present invention does not limit this.

[0057] In the present invention, the active component source can be converted into the corresponding active component in the main catalyst through step (1). Preferably, the active component source is selected from at least one of nitrates, organic acid salts, carbonates, chlorates, sulfates, acetates, chlorides and basic carbonates of active components, such as at least one of nickel nitrate, nickel chloride, nickel acetate, cobalt nitrate, cobalt chloride, cobalt acetate and basic cobalt carbonate; more preferably, it is a nitrate.

[0058] According to a preferred embodiment of the present invention, in step (1), the active component is nickel, and the carrier precursor is selected from precursors containing silicon and aluminum. In this solution, the main catalyst precursor is a nickel-aluminum-silicon precursor.

[0059] According to the present invention, there is no limitation on the method for preparing the main catalyst precursor. In a specific preferred embodiment, in step (1), the method for preparing the main catalyst precursor is a co-precipitation method.

[0060] According to the present invention, preferably, the co-precipitation method comprises: subjecting the carrier precursor and the active component source to a co-precipitation reaction in the presence of a precipitant, and aging and washing the obtained solid product.

[0061] Preferably, the precipitant is selected from at least one of sodium carbonate, sodium metaaluminate, sodium bicarbonate, potassium carbonate, ammonia water and sodium hydroxide.

[0062] The present invention has a wide range of optional dosages for the precipitant, as long as the coprecipitation reaction can occur and a catalyst of the desired composition can be obtained. Those skilled in the art can select the dosage based on actual needs and conventional dosage ranges.

[0063] Preferably, the molar ratio of the precipitant to the total amount of the active component source and the support precursor (e.g., aluminum) calculated as the metal element is (0.5-6):1. In the present invention, the total amount of the active component source and the support precursor calculated as the metal element refers to the sum of the moles of the active component source calculated as the metal element and the moles of the support precursor calculated as the metal element.

[0064] More preferably, the precipitant is sodium hydroxide and sodium carbonate. Those skilled in the art can freely select the ratio of sodium hydroxide and sodium carbonate according to actual needs. For example, the molar ratio of sodium hydroxide to sodium carbonate can be 0.1-40:1. The precipitant is preferably introduced in the form of an aqueous solution, wherein the concentration of sodium hydroxide in the aqueous solution is 0.2-4 mol / L and the concentration of sodium carbonate is 0.1-2 mol / L. Under this preferred embodiment, it is further preferred that the molar ratio of the sodium hydroxide to the total amount of the active component source and the support precursor calculated as the metal element is (2-4):1, and the molar ratio of the sodium carbonate to the total amount of the active component source and the support precursor calculated as the metal element is (0.5-2):1.

[0065] Preferably, the coprecipitation reaction conditions include: a reaction temperature of 30-70°C, and preferably a pH of 7-9 when the coprecipitation reaction is completed. In the present invention, pH refers to the pH of the solution when the coprecipitation reaction is completed. For example, during a complete precipitation reaction, coprecipitation is stopped when pH = 8.

[0066] The present invention does not restrict the order and method of introducing the precipitant, support precursor, and active component source. Those skilled in the art may freely select the method, as long as the primary catalyst precursor can be precipitated. Preferably, the co-precipitation method further comprises a step of mixing the raw materials. The present invention does not restrict the method of mixing. For example, the precipitant can be added to a mixed salt solution containing the support precursor and the active component source, or the mixed salt solution containing the support precursor and the active component source can be added to the precipitant, or both can be added concurrently; the former is preferred. The precipitant is preferably introduced as an aqueous solution, preferably maintained at a constant temperature of 30-70°C. More preferably, the mixed salt solution is prepared by first mixing a portion of the support precursor (preferably as an aqueous solution) and the active component source (preferably as an aqueous solution) (preferably heated to 40-80°C while stirring at 20-150 rpm) to obtain a metal salt mixed solution; and then mixing the metal salt mixed solution with the remaining support precursor (preferably as an aqueous solution) (preferably stirred at 20-150 rpm). The present invention has no limitation on the concentration of the above-mentioned corresponding aqueous solutions, as long as the corresponding solutes can be dissolved. Those skilled in the art can freely choose according to their needs.

[0067] According to the present invention, preferably, the aging conditions include: an aging temperature of 30-70° C., and an aging time of 1-8 hours.

[0068] In the present invention, there is no limitation on the washing after aging. For example, the washing may be performed with deionized water, or with water containing methanol and / or ethanol, and finally with water containing glycerol, citric acid, formic acid, or acetic acid. More preferably, the washing may be performed 2-6 times.

[0069] In the present invention, in step (2), the solid product is subjected to a pre-reduction treatment, specifically a reduction treatment and a passivation treatment.

[0070] According to a specific preferred embodiment of the present invention, in step (2), the reduction treatment can be a single-stage reduction or a multi-stage reduction, preferably a multi-stage reduction.

[0071] In a preferred embodiment, the single-stage reduction process comprises: maintaining the temperature at 100-600° C. for 0.05-8 hours, preferably 150-550° C., and a pressure of 0-2 MPa, preferably 0.2-1.8 MPa.

[0072] More preferably, the single-stage reduction process further comprises: heating to 100-600° C. at a heating rate of 50-150° C. / hour.

[0073] According to one embodiment of the present invention, the reduction temperature of the catalyst is preferably 350-550° C., and the reduction residence time (ie, holding time) is no more than 2 h, preferably 0.05-2 h.

[0074] Preferably, the multi-stage reduction process comprises: gradually increasing the reaction temperature at a heating rate of 60-150°C / hour and keeping the temperature for a period of time in each stage, wherein the reduction temperature in the first stage is 160-300°C, and the reduction temperature in the last stage is 320-520°C, and the holding time in each stage is independently selected from 0.3-8 hours, preferably 0.5-6 hours.

[0075] According to a preferred embodiment of the present invention, the multi-stage reduction process includes: stage 1) heating to 170-280°C at a heating rate of 70-120°C / hour and keeping warm for 0.5-5 hours; stage 2) heating to 330-500°C at a heating rate of 60-150°C / hour and keeping warm for 0.5-5 hours.

[0076] According to another preferred embodiment of the present invention, the multi-stage reduction process includes: stage 1) heating to 180-270°C at a heating rate of 70-120°C / hour and keeping warm for 0.5-5 hours; stage 2) heating to 340-490°C at a heating rate of 60-150°C / hour and keeping warm for 0.5-5 hours.

[0077] In a preferred embodiment of the present invention, stage 2) of the multi-stage reduction comprises: stage 2-1) heating the catalyst to 320-380°C at a heating rate of 50-150°C / hour and holding the temperature for 0.5-6 hours; and stage 2-2) heating the catalyst to 420-490°C at a heating rate of 50-150°C / hour and holding the temperature for 0.3-4 hours. The present invention further utilizes a two-stage temperature-raising reduction method in stage 2) of the multi-stage reduction. This method not only fully reduces the active metals in the catalyst, thereby improving the degree of reduction of the catalyst, but also accelerates heat conduction and diffusion, reducing the adverse effects of water on the reduction.

[0078] According to the present invention, preferably, the hydrogen concentration of the hydrogen-containing gas introduced in stage 2-1) is not lower than that in stage 2-2). Under this preferred embodiment, the reduction process of the catalyst can be promoted, so that the catalyst is uniformly and moderately reduced. According to a preferred embodiment of the present invention, the reduction is carried out at a pressure of 0-0.2 MPa. It should be noted that the pressure is gauge pressure.

[0079] In the present invention, preferably, the volume concentration of hydrogen in the hydrogen-containing gas is 50-90%, more preferably 55-80%.

[0080] Preferably, the hydrogen-containing gas is a mixed gas of hydrogen and a protective gas, and the protective gas is one or more of helium, argon and nitrogen. More preferably, the hydrogen-containing gas is a mixed gas of hydrogen and nitrogen.

[0081] Preferably, the gas-to-agent ratio in the reduction treatment is 200-5000.

[0082] In a specific embodiment, fluidized bed reduction is used. Preferably, the gas-to-agent ratio in the reduction treatment is 700-5000.

[0083] In another specific embodiment, non-fluidized bed reduction is adopted, preferably, the gas-to-agent ratio is 200-2000, more preferably 500-1500.

[0084] According to the present invention, the main equipment for the reduction treatment is a reduction furnace, and the reducing gas (that is, the hydrogen-containing gas) can be passed through once or recycled, preferably recycled. In a specific embodiment, the process flow is: the solid product is loaded into the reduction furnace, and hydrogen is added according to the reduction program for reduction, and the reduced tail gas is heated and recycled after dehydration. More specifically: the solid product is loaded into the pre-reduction reactor, and the system is replaced with N2 to ensure that the volume percentage of O2 in the system is ≤0.5%. The compressor is started to maintain the system pressure at 0.0-2MPa (gauge pressure), and the reduction is carried out according to the heating and hydrogen addition program. In the above-mentioned process operation, the process flow is described as follows: the supplementary reducing gas enters the heat exchanger to exchange heat with the remaining gas after reduction, and then enters the heating furnace for further heating, and then enters the reactor for reduction. After the remaining gas comes out of the bottom of the reactor, it enters the heat exchanger to exchange heat with the cold supplementary reducing gas for cooling. The water inlet condenser is then cooled to 50°C and enters the water separator. The reduced water is separated, compressed by the circulation compressor, dried by the molecular sieve dryer, and then circulated back to the pre-reduction reactor to continue to participate in the reduction, saving a large amount of reducing gas.

[0085] In step (2) of the present invention, preferably, the passivation treatment comprises contacting the catalyst obtained after the reduction treatment with a passivating agent at an initial temperature not exceeding 80°C, and controlling the temperature not to exceed 120°C during the passivation process.

[0086] Preferably, the passivation treatment adopts gas passivation, liquid passivation or solid passivation, more preferably gas passivation.

[0087] Preferably, the passivating agent for gas passivation is an oxidizing gas with an oxygen volume content of 0.01-21%, and the remainder is one or more of argon, nitrogen, carbon dioxide and helium. The temperature during the passivation process is controlled not to exceed 120°C.

[0088] Preferably, the liquid passivation agent is water or oil, etc. In the liquid passivation, the amount of passivation agent can be selected by those skilled in the art according to actual needs, as long as the desired passivation effect can be achieved.

[0089] Preferably, the solid passivation agent is wax, etc. In the solid passivation, the amount of passivation agent can be selected by those skilled in the art according to actual needs, as long as the desired passivation effect can be achieved.

[0090] According to one embodiment of the present application, the main equipment used in the passivation treatment is a passivation furnace. The reduction furnace and the passivation furnace can be configured separately or shared. When the reduction and passivation are performed using the same equipment, it is preferred to introduce a protective gas to replace the hydrogen in the system after the reduction, and then perform the passivation. During the passivation, the passivation temperature is preferably controlled to be within the desired range by adjusting the amount of protective gas (preferably carbon dioxide) pumped in. The passivation gas can be passed through once or recycled. By optimizing the passivation cooling rate, the passivation efficiency and the overall system efficiency are improved. After the reduction of the catalyst is completed, the passivation is performed in the passivation furnace using carbon dioxide or a mixture of carbon dioxide and nitrogen or air, and the temperature in the passivation furnace is controlled to be below 140°C. The passivated gas is recycled or directly discharged.

[0091] According to one embodiment of the present application, the passivation is performed using a gas. The reduced catalyst is moved to a passivation reactor. The passivation step: replace H2 in the system with carbon dioxide or a mixture of carbon dioxide and nitrogen, and rapidly cool. When the volume percentage of H2 in the system is ≤1% and the temperature in the reactor is below 140°C, introduce O2 and perform multi-stage passivation. The amount of carbon dioxide pumped in is adjusted to ensure that the temperature in the reactor does not exceed 140°C, preferably does not exceed 120°C.

[0092] In a preferred embodiment of the present application, the method further comprises: in step (2), cooling the catalyst obtained after the reduction treatment to below 100°C, preferably to below 80°C, and further preferably to below 50°C, introducing a low-concentration oxidizing gas below 100°C, preferably below 80°C, for the passivation, and the oxygen concentration of the oxidizing gas is continuously increased.

[0093] In the present invention, the "oxygen concentration of the oxidizing gas continues to increase" means that the oxygen concentration in the introduced oxidizing gas shows an overall upward trend. For example, 1. The oxygen concentration in the introduced oxidizing gas can continue to increase (that is, the oxygen concentration increases at a certain rate); 2. The oxygen concentration in the introduced oxidizing gas can also be stably introduced for a certain period of time and then increased. In this case, the oxygen concentration increases in stages. For example, in multiple stages, in one specific embodiment, the oxygen concentration in the latter stage is higher than the oxygen concentration in the previous stage. In another specific embodiment, the oxygen concentrations in the first few stages are the same and lower than the oxygen concentration in the subsequent stages, thereby showing an overall upward trend.

[0094] The present invention has a wide range of options for the degree of continuous increase in the oxygen concentration of the oxidizing gas. It can be a regular continuous increase, for example, a continuous increase of 2 times, or an exponential continuous increase; it can also be an irregular continuous increase, for example, the oxygen concentration in the second stage is 1 times that of the oxygen concentration in the first stage, the oxygen concentration in the third stage is 1.2 times that of the oxygen concentration in the second stage, and the oxygen concentration in the fourth stage is 2 times that of the oxygen concentration in the third stage.

[0095] In the present invention, preferably, the oxygen concentration of the oxidizing gas is continuously increased in stages. In this case, the present invention has a wide range of optional durations for the various stages, as long as it is beneficial to improving the performance of the resulting catalyst. More preferably, during the passivation process, when the oxidizing gas introduced in the previous stage makes the oxygen concentration in the passivation outlet gas equal to the oxygen concentration of the introduced oxidizing gas, the oxidizing gas is introduced in the next stage.

[0096] According to the present invention, preferably, during the passivation process, the oxygen concentration of the oxidizing gas is continuously increased in at least three stages. It is understood that, under this preferred embodiment, the oxygen concentration of the oxidizing gas in the first stage is lower than the oxygen concentration of the oxidizing gas in the second stage, and the oxygen concentration of the oxidizing gas in the second stage is lower than the oxygen concentration of the oxidizing gas in the third stage, and so on. Furthermore, it is understood that the relative multiples of the oxygen concentration of the oxidizing gas in each adjacent stage can be independently the same or different. For example, if the relative multiple of the oxygen concentration of the oxidizing gas in the first and second stages is 1.5, the relative multiples of the oxygen concentration of the oxidizing gas in the second and third stages can be 1.5 or 2.

[0097] In a preferred embodiment, the passivation treatment is preferably performed in at least three stages, more preferably in 3-12 stages. For example, the number of stages can be any of 4, 5, 6, 7, 8, 9, 10, 11, and 12, more preferably in 4-9 stages. The oxygen concentration in the oxidizing gas increases in each stage. This preferred embodiment of the present invention allows for more uniform passivation of the catalyst, thereby facilitating reactivation of the catalyst through reduction and resulting in a greater number of active sites.

[0098] In a preferred embodiment, the passivation treatment is divided into three stages: a first stage with an oxygen concentration of 0.01% to 0.2%, a second stage with an oxygen concentration of 0.2% to 1%, and a third stage with an oxygen concentration of 1% to 21%. Preferably, the passivation treatment time is allocated such that the ratio of the first passivation stage: the second passivation stage: the third passivation stage is (4-9): (0.5-1): (0.5-1).

[0099] In the present invention, there is no limitation on the method for cooling the catalyst obtained after the reduction, as long as the catalyst can be cooled to the desired temperature, for example, cooling by heat exchange, cold exchange, water cooling, ammonia cooling, etc. In the present invention, preferably, the method further comprises: in step (2), after cooling the catalyst obtained by the reduction treatment, purging it with a protective gas, and then performing the passivation.

[0100] According to a preferred embodiment of the present invention, during the passivation treatment, the initial oxygen concentration of the oxidizing gas introduced is 0.01-0.1% by volume, preferably 0.02-0.1% by volume. Using an oxidizing gas with a lower initial oxygen concentration can make the passivation uniform and controllable, and is more conducive to obtaining a catalyst that is easily reducible.

[0101] According to a preferred embodiment of the present invention, during the passivation treatment, the oxygen concentration of the oxidizing gas introduced in the latter stage is 1.5-6 times the oxygen concentration of the oxidizing gas introduced in the previous stage. This preferred embodiment enables more uniform and controllable passivation of the catalyst, resulting in a catalyst with more reducing active sites after re-reduction treatment and high passivation efficiency. In the present invention, preferably, the concentration of the oxidizing gas introduced in the final stage of the passivation process is 21% by volume, i.e., air is introduced.

[0102] In the present invention, the passivation operation is terminated when the reactor temperature does not rise and the oxygen contents at the inlet and outlet are substantially the same. Depending on the actual situation, the total passivation time of the passivation treatment of the present invention is generally 0.3-40 hours. In contrast, the passivation time in the prior art pre-reduction method is generally more than 48 hours.

[0103] According to the present invention, preferably, the gas-to-agent ratio of the passivation treatment is 200-5000, more preferably 500-3000, such as any value among 500, 1000, 1200, 1500, 2000, 3000 and any value and range therebetween.

[0104] According to the present invention, preferably, during the passivation process, the gas-to-agent ratio in the early stage is not lower than that in the later stage. This preferred solution is more conducive to promoting a uniform passivation process of the catalyst and improving the passivation efficiency.

[0105] In the present invention, the reduction treatment is carried out in a reduction reactor, and the passivation treatment is carried out in a passivation reactor. The reduction reactor and the passivation reactor can be the same reactor or different reactors. In the present invention, there is no limitation on the equipment used for the reduction and passivation. The reduction reactor and the passivation reactor can be independently selected from any one of a rotary kiln reactor, a fluidized bed reactor, and a rotary drum reactor. A fluidized bed reactor is preferred, and a fluidized bed reactor with a riser is more preferred. The fluidized bed gas volume is selected based on the principle of fluidizing the powdered catalyst. The present invention can also be equipped with a heat exchanger, a cold exchanger, a water cooler, an ammonia cooler, a dryer, a regenerative heating furnace, and a circulating fan. According to the present invention, the main equipment for reducing the oxidized hydrogenation catalyst is a reduction furnace. The reducing gas can be passed through once or recycled, preferably recycled. In one specific embodiment, the process flow is as follows: the oxidized catalyst is loaded into the reduction furnace, hydrogen is added according to the reduction procedure for reduction, and the reduced tail gas is dehydrated and then heated for recycling. More specifically: the catalyst is loaded into the pre-reduction reactor, the system is replaced with N2 to ensure that the volume percentage of O2 in the system is ≤0.5%, the compressor is started, the system pressure is maintained at 0.0-2MPa (gauge pressure), and reduction is carried out according to the temperature increase and hydrogen distribution program. In the above-mentioned process operation, the process flow is described as follows: the supplementary reducing gas enters the heat exchanger to exchange heat with the residual gas after reduction, then enters the heating furnace for further heating, and then enters the reactor for reduction. After the residual gas exits the bottom of the reactor, it enters the heat exchanger to exchange heat with the cold supplementary reducing gas for cooling. The water inlet condenser is then cooled to 50°C and enters the water separator. The reduced water is separated, compressed by the circulation compressor, dried by the molecular sieve dryer, and then circulated back to the pre-reduction reactor to continue participating in the reduction, saving a large amount of reducing gas.

[0106] In one embodiment of the present invention, the reduction and passivation processes utilize a dual reactor configuration, with supporting equipment including a powder preheating furnace, a gas preheating furnace, a feeding device, a reduction reactor, an intermediate tank, and a passivation reactor. The specific process includes: preheating a prepared reducing gas to a certain temperature in the gas preheating furnace before entering the reduction reactor. Powder of a certain particle size is preheated in the powder preheating furnace and placed into the feed bin of the feeding device. The powder is then introduced into the reduction reactor, where the reducing gas contacts the powder and a reduction reaction occurs. Gas-solid separation is then achieved in a cyclone dust collector. The resulting solid is then transferred to an intermediate tank, cooled, and then fed to the passivation reactor for passivation. Compared to existing technologies, this invention improves the pre-reduction rate and equipment utilization, resulting in high efficiency, low energy consumption, and low production costs. Specifically, when the powder particle size is reduced to below 2000 μm, fine powders can be processed using a rapid circulating fluidized bed or conveyor reactor. The required gas velocity is lower than that of coarse powders, while the reaction rate of fine powders is also faster, resulting in high reactor efficiency.

[0107] According to the present invention, in step (3), the product obtained in step (2) after the reduction treatment and passivation treatment is formed. After passivation, the metal surface is protected by an oxide film, and tableting and crushing in air will not cause oxidation of the internal metal. The forming process can be, for example, ball rolling, tableting or extrusion, preferably tableting. The product is formed into a desired shape suitable for the reaction, such as a cylinder, a hollow cylinder, a wheel, a four-hole cylinder, etc.

[0108] In the forming step (3) of the present invention, there is no limitation on the preparation method of the co-catalyst, as long as it has the aforementioned required composition, preferably co-impregnation or co-precipitation. The co-impregnation or co-precipitation method can be carried out according to conventional methods in the prior art, and the co-precipitation method is preferably the same as the co-precipitation process described above.

[0109] The present invention particularly introduces a co-catalyst in step (3) so that a certain distance exists between the co-catalyst and the active component, and the distance is moderate, which is more conducive to improving the reaction activity and stability of the obtained catalyst.

[0110] In the present invention, the optional ranges of the molding agent and lubricant are the same as those in the first aspect and are not further described herein. The present invention does not impose any restrictions on the amount of the lubricant, and those skilled in the art can freely select the amount as needed. Preferably, the amount of the lubricant is less than 3% by weight based on the total amount of the catalyst obtained after molding.

[0111] Preferably, the co-catalyst further comprises at least one noble metal. The noble metal elements are the same as those described in the first aspect and are not further described herein. Preferably, the noble metal element is used in an amount such that the content of the noble metal in the prepared catalyst, calculated as the element, is 0.005-0.05% by weight, based on the total weight of the hydrogenation catalyst.

[0112] During the molding process of the present invention, those skilled in the art may also choose whether to add other additives, such as a molding agent, according to actual needs. The molding process may be, for example, selected from one or more of methylcellulose, sesbania powder, cement, and water, and the present invention has no limitation thereto. The present invention has a wide range of choices for the amount of the molding agent, and as long as molding is possible, those skilled in the art may make an adaptable selection according to actual conditions.

[0113] The present invention rapidly reduces smaller particles so that the oxides in the catalyst are fully reduced, thereby improving the reduction degree of the hydrogenation catalyst and keeping the crystals smaller, thereby efficiently reducing the catalyst. Furthermore, after specific passivation, the reduction and passivation efficiency is high. The catalyst is then shaped and a co-catalyst is introduced during the shaping process, so that a large-particle catalyst that is very uniform, easy to regenerate, and has many active centers can be obtained, thereby improving the overall reaction activity and stability of the catalyst, especially greatly improving the stability, and having good industrial application prospects.

[0114] The third aspect of the present invention provides a high-stability pre-reduction HPPO circulating methanol hydrogenation catalyst prepared by the method described in the second aspect.

[0115] The high-stability pre-reduction HPPO circulating methanol hydrogenation catalyst of the present invention is the same as the catalyst of the first aspect described above, and will not be described in detail here.

[0116] The fourth aspect of the present invention provides use of the high-stability pre-reduction HPPO cycle methanol hydrogenation catalyst described in the first aspect or the third aspect in the purification of HPPO cycle methanol.

[0117] According to the present invention, preferably, the application method comprises: reducing the catalyst at 150-250° C. for 2-24 hours in a hydrogen-containing atmosphere; and then performing hydrogenation purification treatment on the raw material under circulating methanol purification reaction conditions.

[0118] In the present invention, the hydrogen-containing atmosphere can be hydrogen or a mixture of hydrogen and an inert gas, wherein the inert gas is at least one of argon, nitrogen, helium, and neon. The concentration of hydrogen in the hydrogen-containing atmosphere is preferably 40-100% by volume.

[0119] Preferably, the gas-to-agent ratio of the re-reduction is 500-5000.

[0120] Preferably, the circulating methanol purification reaction conditions include: temperature of 50-150°C, pressure of 1-6 MPa, and hourly space velocity of the raw material liquid of 3-10 h -1 , V(H2) / V(raw material) is 100-800. The raw material refers to a circulating methanol solution.

[0121] More preferably, the circulating methanol purification reaction conditions include: temperature of 60-130°C, pressure of 2-6 MPa, and hourly space velocity of the raw material liquid of 4-10h -1 , V(H2) / V(raw material) is 200-800.

[0122] The methanol solvent used in the HPPO cycle will dissolve impurities produced by the reaction or side reactions, which will affect the epoxidation reaction, so the circulating methanol needs to be purified. Generally, the circulating methanol contains impurities such as aldehydes, peroxides, and ketones, all of which can be used in the present invention. Preferably, the methanol content in the circulating methanol is 70-95% by volume.

[0123] Preferably, the total mass concentration of acetaldehyde and hydrogen peroxide (H2O2) in the raw material is 100-10000 ppm, more preferably 1000-10000 ppm, further preferably 5000-10000 ppm.

[0124] In a specific preferred embodiment of the present invention, the mass concentration of acetaldehyde in the raw material is 100-2000 ppm, and the total mass concentration of hydrogen peroxide (H2O2) is 1000-6000 ppm.

[0125] The present invention will be described in detail below through examples.

[0126] In the following examples, the particle size is measured using a laser particle size analyzer, specifically a Malvern laser particle size analyzer Mastersizer 2000. The particle size is characterized by Dv(90). When Dv(90) is 100 μm, it means that 90% of the particles are smaller than 100 μm.

[0127] Temperature-programmed reduction (TPR) characterization was performed using an Autochem 2950 fully automated high-pressure chemical adsorption instrument manufactured by Micromeritics. The following test conditions were used: a 0.20 g sample was first heated to 120°C for dehydration at a heating rate of 10°C / min under a 50 mL / min Ar flow for 1 hour. After the temperature dropped to 50°C, a TPR experiment was performed. The TPR experimental conditions and procedure were as follows: a reducing gas consisting of a 10 vol% H₂-Ar mixture at a flow rate of 50 mL / min, and the temperature was raised to 900°C at a heating rate of 10°C / min. During this heating process, the signal was detected by a thermal conductivity detector (TCD) to produce a TPR curve. The temperature corresponding to the peak of the largest low-temperature reduction peak in the TPR curve was used as an indicator for evaluating the regeneration performance of the passivated catalyst. The lower the temperature corresponding to the peak of the largest low-temperature reduction peak, the easier the catalyst is to regenerate.

[0128] The number of active centers was characterized using TPD. The number of active centers was determined using H2 temperature-programmed desorption (H2-TPD) on an Autochem 2950 fully automatic high-pressure chemical adsorption instrument manufactured by Micromeritics, USA. The test method was as follows: 0.2000 g of a 40-60 mesh sample was weighed and first subjected to re-reduction activation. The re-reduction conditions were: a H2-Ar mixture with a hydrogen content of 10% by volume and a flow rate of 50 mL / min, heated to 200°C at a heating rate of 10°C / min, and reduced for 2 hours. The re-reduced catalyst was then cooled in a H2-Ar mixture with a hydrogen content of 10% by volume. After the temperature dropped to 55°C, it was purged with Ar gas at a flow rate of 20 mL / min until the baseline stabilized. The H2-TPD experiment was then performed. The experimental conditions and procedures of H2-TPD were as follows: carrier gas was Ar, carrier gas flow rate was 20 mL / min, heating rate was 10 °C / min, final temperature was 400 °C, thermal conductivity detector (TCD) was used to detect the signal, and TPD curve was obtained.

[0129] The reduction degree is tested by first measuring the TPR curve of 0.2g of the pre-reduced catalyst; then, calcining the pre-reduced catalyst in air at 450°C for 2h to obtain an oxidized catalyst, and then measuring the TPR curve of the oxidized catalyst using the same TPR testing method. The temperature corresponding to the peak of the low-temperature reduction peak with the largest area in the TPR curve is the re-reduction temperature of the sample. The reduction degree of the pre-reduced catalyst is calculated from the TPR curve: reduction degree = (direct reduction TPR peak area of ​​the oxidized catalyst - high-temperature unreduced peak area of ​​the pre-reduced catalyst) / direct reduction TPR peak area of ​​the oxidized catalyst * 100%.

[0130] Example 1

[0131] Step 1. Preparation of oxidized catalyst

[0132] Dissolve 198 kg of Ni(NO3)2·6H2O and 20 kg of Al(NO3)3·9H2O in 500 L of deionized water to prepare a mixed metal salt solution. Maintain the mixed metal salt solution at a constant temperature of 45°C. Add 85 kg of silica sol GS-30 (silicon oxide concentration: 30 wt%) to 100 L of water and stir at 50 rpm to obtain diluted silica sol. Mix the mixed metal salt solution and diluted silica sol and stir at 50 rpm to obtain a catalyst base solution.

[0133] Then, 110 kg of Na2CO3 was dissolved in 500 L of deionized water to prepare a precipitant solution. The precipitant solution was maintained at a constant temperature of 45°C and gradually added dropwise to the catalyst base liquid while stirring continuously for a complete precipitation reaction. The pH value was set as the titration end point at 8. After stirring evenly, the mixture was aged at 45°C for 2 hours. The precipitated precursor was washed three times with deionized water to obtain a filter cake.

[0134] The filter cake and water were slurried and stirred for 1.5 hours to obtain a slurry with a solid content of 35 wt%. The slurry was transported to a spray dryer with an atomization pressure of 2.5 MPa, an inlet temperature of 330°C, and an outlet temperature of 130°C. After 5 seconds, the slurry flowed out of the outlet of the spray dryer to obtain microsphere particles with a particle size Dv(90) of 154 μm, and then calcined at 370°C for 3 hours.

[0135] Step 2. Reduction passivation

[0136] The calcined powder obtained in step 1 was passed through a 40-mesh sieve and then transported to a fluidized bed reduction reactor. A nitrogen replacement system was first introduced into the reactor until the oxygen content was qualified (oxygen content ≤ 0.5 volume %), and then hydrogen was added to obtain a 60 volume % hydrogen-nitrogen mixed gas. The 60 volume % hydrogen-nitrogen mixed gas was preheated by controlling the opening of the preheating furnace to raise the catalyst bed to 420° C. at 100° C. / hour for 2 h, and the pressure was 0.2 MPa, with a gas-to-agent ratio of 2000.

[0137] Then nitrogen is introduced to replace the hydrogen in the system, and the above reduced catalyst is cooled to below 55°C. An oxygen-containing gas with an oxygen concentration of 0.2-21 vol% is introduced at atmospheric pressure, the gas / catalyst ratio is 2000, and the oxygen-containing gas with oxygen concentrations of 0.2 vol%, 0.6 vol%, 1.0 vol%, 3.0 vol%, 8.0 vol%, and 21 vol% is introduced in 6 stages, respectively. After the introduction of the oxygen-containing gas in the previous stage, the oxygen-containing gas in the next stage is introduced when the oxygen concentration at the gas outlet is equal to the oxygen concentration at the gas inlet. The oxygen concentration is gradually increased in this way until the passivation is completed. During the passivation, the passivation temperature of the catalyst bed is controlled to be less than 80°C, and the passivation time is 2h. A pre-reduced hydrogenation catalyst is obtained.

[0138] Step 3. Shaping

[0139] The product obtained in step 2 is mixed with a promoter (specific composition: 8 wt% MnO2 / Al2O3, the amount of the promoter is such that the composition of the obtained hydrogenation catalyst satisfies the following), calcium aluminate cement, and graphite in a ratio of 90:10:8:2, and is pressed into a circular tablet with a particle size of 4x4mm to obtain a shaped pre-reduced hydrogenation catalyst C1.

[0140] The reduction degree of the obtained catalyst is tested, and the obtained catalyst is characterized by TPR and TPD. The results are shown in Table 1.

[0141] Example 2

[0142] Compared with Example 1, the only difference is the reduction condition, which is: reduction at 120°C / h to 430°C for 2h, 70 vol% hydrogen-nitrogen mixed gas, and a gas / catalyst ratio of 2500. A pre-reduced hydrogenation catalyst C2 is obtained.

[0143] Example 3

[0144] Compared with Example 1, the only difference is the reduction and passivation condition, which is:

[0145] The dry powder obtained in step 1 of Example 1 is transported to a fluidized bed reduction reactor after being sieved through a 40 mesh sieve. Nitrogen is first introduced into the reactor to replace the system until the oxygen is qualified (oxygen content ≤0.5 vol%). Then, 70 vol% hydrogen-nitrogen mixed gas is obtained by supplementing hydrogen, and the 70 vol% hydrogen-nitrogen mixed gas is preheated by controlling the opening degree of the preheating furnace to reduce the catalyst bed to 440°C at a rate of 100°C / h for 1h. The pressure is 0.2 MPa, and the gas / catalyst ratio is 2500.

[0146] Then, nitrogen was introduced to replace the hydrogen in the system, and the reduced catalyst was cooled to below 55°C. An oxygen-containing gas with an oxygen concentration of 0.1-21% by volume, which was prepared from air and nitrogen, was introduced at below 55°C under normal pressure. The gas-to-agent ratio was 2000, and oxygen-containing gas with oxygen concentrations of 0.1%, 0.2%, 0.6%, 1.0%, 3.0%, 8.0%, and 21% by volume was introduced in 7 stages. After the oxygen-containing gas of the previous stage was introduced, when the oxygen concentration at the gas outlet was equal to the oxygen concentration at the gas inlet, the oxygen-containing gas of the next stage was introduced. The oxygen concentration was gradually increased for passivation until the passivation was completed. During this period, the passivation temperature of the catalyst bed was controlled to be less than 70°C, and the passivation time was 2 hours to obtain a pre-reduction hydrogenation catalyst C3.

[0147] Example 4

[0148] Compared with Example 1, the difference is:

[0149] The filter cake was prepared in the same manner as in Example 1, except that the filter cake was dried at 160°C for 4 hours and then crushed to a particle size of D V (90) is less than 700 μm. After calcination at 400°C for 4 h, reduction passivation is performed as in Example 1, except that the reduction is performed at 400°C for 4 h in a 40 vol% hydrogen-nitrogen mixed atmosphere. The temperature is then lowered to 55°C and passivation is performed as in Example 1. During this period, the passivation temperature of the catalyst bed is controlled to be less than 80°C.

[0150] Then, the molding process of Example 1 was carried out, except that the catalyst was pressed into pellets with a particle size of 5×5 mm after molding to obtain the pre-reduction hydrogenation catalyst C4.

[0151] The reduction degree of the obtained catalyst was tested, and the obtained catalyst was characterized by TPR and TPD. The results are shown in Table 1.

[0152] Example 5

[0153] Compared with Example 1, the difference is:

[0154] The spray-dried powder was not calcined and directly subjected to reduction passivation as in Example 1. The product obtained in Step 2 was then weighed and uniformly mixed with a co-catalyst (specifically, a composition of 16 wt% MoO3 / Al2O3), calcium aluminate cement, and graphite in a ratio of 90:10:10:3, and pressed into 4×4 mm discs to obtain pre-reduced hydrogenation catalyst C5.

[0155] Example 6

[0156] Compared to Example 3, the only difference was the amounts of the primary catalyst, co-catalyst, molding agent, and lubricant added, and the co-catalyst was 16 wt% MoO3 / Al2O3. The product obtained in Step 2 was weighed and uniformly mixed with the co-catalyst, calcium aluminate cement, and graphite in a ratio of 90:10:8:2, and pressed into 4×4 mm pellets to obtain pre-reduction hydrogenation catalyst C6.

[0157] Table 1

[0158] Example catalyst Reduction temperature, ℃ Reduction degree, % Number of active centers, mmol hydrogen / g catalyst 1 C1 165 86 0.23 2 C2 167 89 0.25 3 C3 162 92 0.26 4 C4 164 85 0.19 5 C5 161 86 0.23 6 C6 163 93 0.26

[0159] The re-reduction temperature refers to the temperature corresponding to the peak of the low-temperature reduction peak with the largest area in the TPR spectrum curve.

[0160] The results in Table 1 indicate that the catalyst prepared using the method of the present invention exhibits a high degree of reduction and a high number of active centers, indicating that the pre-reduced catalyst obtained through the pre-reduction treatment contains a higher proportion of catalytically active nickel and exhibits an appropriate degree of reduction. The TPR peak temperature indicates that the catalyst of the present invention exhibits excellent regeneration performance.

[0161] Test Case

[0162] The reaction performance of the pre-reduced catalysts obtained in the above examples and comparative examples in the HPPO cycle methanol hydrogenation was evaluated in a fixed bed reactor. The catalyst dosage was 10 mL of 40-60 mesh.

[0163] The catalyst needs to be reduced before use. Reduction conditions: pressure is normal pressure, reducing gas is a hydrogen-nitrogen mixture with a hydrogen concentration of 70% by volume, gas-to-agent ratio is 1000, reduction temperature is 200°C, reduction time is 2h. Then, at temperature 60°C, pressure 2.0MPa, raw material liquid hourly space velocity 8h -1 Catalyst performance was evaluated under the conditions of a V(H2) / V(feedstock) ratio of 500, with recycled methanol (methanol content of 85% by volume), an acetaldehyde concentration of 1500 ppm, and a hydrogen peroxide (H2O2) concentration of 5000 ppm. The results are listed in Table 2.

[0164] Table 2

[0165]

[0166]

[0167] Note: The 90% conversion rate stability time refers to the time when the acetaldehyde conversion rate remains at 90% without decreasing.

[0168] The results in Table 2 show that the pre-reduction catalyst of the present invention has good reaction performance and stability in HPPO cycle methanol purification.

[0169] The catalyst reduction and passivation treatment process of the present invention is simple to operate, employs mild conditions, achieves a good passivation effect, and exhibits excellent catalyst regeneration. The surface of the catalyst treated by the present invention is oxidized to form a dense oxide film, which prevents deep oxidation of the interior of the catalyst by air, facilitating storage and transportation. Furthermore, the catalyst is easily reduced by H2 during use, rapidly exhibiting high catalytic activity comparable to that of in-situ reduced catalysts in terms of activity and stability. This significantly shortens the start-up time and brings good economic benefits to the enterprise.

[0170] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A high-stability pre-reduction HPPO circulating methanol hydrogenation catalyst, comprising a main catalyst and a co-catalyst, each containing a carrier and an active component. Based on the total amount of the hydrogenation catalyst, the main catalyst content is 77-95% by weight, and the co-catalyst content is 5-23% by weight, calculated as oxide. The active components of the main catalyst include Ni and / or Co, and the active components of the co-catalyst include Mo and / or Mn; based on the total amount of the hydrogenation catalyst, the content of Ni and / or Co is 25-65% by weight, and the content of Mo and / or Mn is 0.05-2.4% by weight, calculated as oxides; The number of active centers of the hydrogenation catalyst after the reduction treatment is 0.23-0.48 mmol hydrogen / g catalyst, and the reduction treatment conditions include: temperature of 200° C., time of 2 hours, reduction atmosphere of hydrogen and argon with a hydrogen concentration of 10% by volume, and a gas-to-agent ratio of 15000; A method for preparing a highly stable pre-reduction HPPO circulating methanol hydrogenation catalyst comprises: (1) preparing a main catalyst precursor from a carrier precursor and an active component source containing Ni and / or Co, drying and / or calcining the main catalyst precursor and optionally pulverizing the main catalyst precursor to obtain a solid product having a particle size of 5-154 μm; (2) subjecting the solid product to reduction treatment and passivation treatment in sequence, wherein the reduction treatment is carried out in the presence of a hydrogen-containing gas; the passivation treatment is carried out in the presence of a passivating agent, and the passivation conditions include: a passivation temperature not exceeding 140° C.; (3) The product obtained in step (2) is mixed with a co-catalyst and an optional shaping agent and / or an optional lubricant to form a slurry.

2. The catalyst according to claim 1, wherein The carrier in the main catalyst is selected from at least one of aluminum oxide, silicon oxide, zirconium oxide and titanium oxide; The carrier in the co-catalyst is selected from at least one of Group IIA metal oxides, Group VIB metal oxides, Group VIIB metal oxides, Group IIB metal oxides, Group IIIA metal oxides and activated carbon.

3. The catalyst according to claim 2, wherein The carrier in the co-catalyst is selected from at least one of magnesium oxide, zinc oxide, calcium oxide, aluminum oxide and activated carbon.

4. The catalyst according to any one of claims 1 to 3, wherein The promoter further comprises at least one noble metal.

5. The catalyst according to claim 4, wherein The promoter further comprises at least one of Pt, Pd, Ir, Rh and Ru. The catalyst according to claim 5, wherein Based on the total amount of the hydrogenation catalyst, the content of the noble metal in terms of element is 0.005-0.05 wt %.

7. The catalyst according to any one of claims 1 to 3, wherein The catalyst also includes a molding agent and / or a lubricant. Based on the total amount of the hydrogenation catalyst, calculated as oxide, the content of the main catalyst is 77-93 weight %, the content of the co-catalyst is 5-11 weight %, and the total content of the molding agent and / or lubricant is 2-12 weight %.

8. The catalyst according to claim 7, wherein The forming agent comprises at least one of methylcellulose, sesbania powder, cement and water, and the lubricant comprises at least one of graphite, paraffin oil, ester lubricant, talc, stearic acid and palmitic acid and metal or alkali metal salts of these acids.

9. The catalyst according to claim 8, wherein The particle size of the hydrogenation catalyst is 2-8 mm.

10. The catalyst according to any one of claims 1 to 3, wherein The number of active centers of the hydrogenation catalyst after re-reduction treatment is 0.23-0.45 mmol hydrogen / g catalyst.

11. The catalyst according to any one of claims 1 to 3, wherein According to TPR characterization, in the TPR curve of the catalyst, the temperature corresponding to the peak of the low-temperature reduction peak with the largest area is 125-245°C.

12. A method for preparing the highly stable pre-reduction HPPO circulating methanol hydrogenation catalyst according to claim 1, comprising: (1) preparing a main catalyst precursor from a carrier precursor and an active component source containing Ni and / or Co, drying and / or calcining the main catalyst precursor and optionally pulverizing the main catalyst precursor to obtain a solid product having a particle size of 5-154 μm; (2) subjecting the solid product to reduction treatment and passivation treatment in sequence, wherein the reduction treatment is carried out in the presence of a hydrogen-containing gas; the passivation treatment is carried out in the presence of a passivating agent, and the passivation conditions include: a passivation temperature not exceeding 140° C.; (3) mixing the product obtained in step (2) with a co-catalyst and an optional shaping agent and / or an optional lubricant to form a mixture; the co-catalyst comprises a carrier and an active component, and the active component in the co-catalyst comprises Mo and / or Mn; The amounts of the carrier precursor, the active component source, the co-catalyst, the shaping agent and the lubricant are such that, in the prepared catalyst, based on the total amount of the hydrogenation catalyst, the content of the main catalyst, calculated as oxide, is 77-95% by weight, the content of the co-catalyst is 5-23% by weight, and the total content of the shaping agent and / or lubricant is 0-12% by weight; and the content of Ni and / or Co is 25-65% by weight, and the content of Mo and / or Mn is 0.05-2.4% by weight.

13. The method according to claim 12, wherein: The drying process includes: drying the main catalyst precursor at 80-180° C. for 2-24 hours.

14. The method according to claim 13, wherein The drying process includes: slurrying the main catalyst precursor to obtain a slurry with a solid content of 15-50% by weight, and spray drying the slurry.

15. The method according to claim 14, wherein The spray drying conditions include: atomization pressure of 1-5 MPa, inlet temperature of 250-400° C., outlet temperature of 80-160° C., and atomization drying time of 2-5 seconds.

16. The method according to any one of claims 12 to 15, wherein: The calcination conditions include: a calcination temperature of 300-500° C. and a calcination time of 2-10 hours.

17. The method according to any one of claims 12 to 15, wherein: The particle size of the solid product is 10-154 μm.

18. The method according to claim 17, wherein The particle size of the solid product is 50-154 μm.

19. The method according to any one of claims 12 to 15, wherein: The amounts of the carrier precursor, the active component source, the co-catalyst, the shaping agent and the lubricant are such that, in the prepared catalyst, based on the total amount of the hydrogenation catalyst and calculated as oxide, the content of the main catalyst is 77-93 wt %, the content of the co-catalyst is 5-11 wt % and the total content of the shaping agent and / or lubricant is 2-12 wt %.

20. The method according to any one of claims 12 to 15, wherein: The carrier in the main catalyst precursor is selected from at least one of aluminum oxide, silicon oxide, zirconium oxide, titanium oxide and zinc oxide; And / or, the carrier precursor is selected from at least one of silica sol, water glass, aluminum sol, sodium metaaluminate, aluminum nitrate, aluminum chloride, zinc nitrate, zirconium nitrate and tetrabutyl titanate; And / or, the active component source is selected from at least one of nitrates, organic acid salts, carbonates, chlorates, sulfates, acetates, chlorides and basic carbonates of active components.

21. The method according to any one of claims 12 to 15, wherein: The carrier in the co-catalyst is selected from at least one of Group IIA metal oxides, Group VIB metal oxides, Group VIIB metal oxides, Group IIB metal oxides, Group IIIA metal oxides and activated carbon.

22. The method according to claim 21, wherein The carrier in the co-catalyst is selected from at least one of magnesium oxide, zinc oxide, calcium oxide, aluminum oxide and activated carbon.

23. The method according to any one of claims 12 to 15, wherein: In step (1), the method for preparing the main catalyst precursor is a co-precipitation method.

24. The method according to claim 23, wherein The co-precipitation method comprises: carrying out a co-precipitation reaction on a carrier precursor and an active component source in the presence of a precipitant, and aging and washing the obtained solid product.

25. The method according to claim 24, wherein The precipitant is selected from at least one of sodium carbonate, sodium metaaluminate, sodium bicarbonate, potassium carbonate, ammonia water and sodium hydroxide; And / or, the molar ratio of the precipitant to the total amount of the active component source and the carrier precursor calculated as metal elements is (0.5-6):

1.

26. The method according to claim 24, wherein The conditions of the coprecipitation reaction include: a reaction temperature of 30-70° C., and a pH of 7-9 when the coprecipitation reaction is completed; And / or, the aging conditions include: an aging temperature of 30-70° C. and an aging time of 1-8 hours.

27. The method according to claim 24, wherein The pH value when the coprecipitation reaction is completed is 7-9.

28. The method according to any one of claims 12 to 15, wherein: In step (2), the reduction treatment is a single-stage reduction or a multi-stage reduction; The single-stage reduction process includes: maintaining a constant temperature of 100-600° C. for 0.05-8 hours and a pressure of 0-2 MPa; The multi-stage reduction process includes gradually increasing the reaction temperature at a heating rate of 60-150°C / hour and holding the temperature for a period of time in each stage, wherein the reduction temperature in the first stage is 160-300°C, and the reduction temperature in the last stage is 320-520°C. The holding time in each stage is independently selected from 0.3-8 hours.

29. The method according to claim 28, wherein The single-stage reduction process further includes: heating to 100-600° C. at a heating rate of 50-150° C. / hour.

30. The method according to any one of claims 12 to 15, wherein: The volume concentration of hydrogen in the hydrogen-containing gas is 50-90%; And / or, the hydrogen-containing gas is a mixed gas of hydrogen and a protective gas, and the protective gas is one or more of helium, argon and nitrogen; And / or, the gas-to-agent ratio in the reduction treatment is 200-5000.

31. The method according to any one of claims 12 to 15, wherein: In step (2), the passivation treatment includes contacting the catalyst obtained after the reduction treatment with a passivating agent under the condition that the initial temperature does not exceed 80°C, and the temperature is controlled not to exceed 120°C during the passivation process.

32. The method according to claim 31, wherein In step (2), the passivation treatment adopts gas passivation, liquid passivation or solid passivation.

33. The method according to claim 32, wherein The passivation agent for gas passivation is an oxidizing gas with an oxygen volume content of 0.01-21%, and the balance is one or more of argon, nitrogen, carbon dioxide and helium. The temperature during the passivation process is controlled not to exceed 120°C.

34. The method of claim 32, wherein: The passivation treatment adopts gas passivation and is carried out in at least three stages, and the oxygen concentration in the oxidizing gas is continuously increased in each stage; And / or, in the passivation treatment, the oxygen concentration of the oxidizing gas introduced in the latter stage is 1.5-6 times the oxygen concentration of the oxidizing gas introduced in the former stage.

35. The method according to claim 34, wherein The passivation treatment adopts gas passivation and is carried out in 3-12 stages, and the oxygen concentration in the oxidizing gas increases continuously in each stage.

36. The method according to claim 35, wherein The passivation treatment adopts gas passivation and is carried out in 4-9 stages, and the oxygen concentration in the oxidizing gas increases continuously in each stage.

37. The method of claim 34, wherein: During the passivation treatment, the initial oxygen concentration of the introduced oxidizing gas is 0.01-0.1 volume %.

38. The method of claim 37, wherein: During the passivation treatment, the initial oxygen concentration of the introduced oxidizing gas is 0.02-0.1 volume %.

39. The method of claim 34, wherein: The gas-to-agent ratio of the passivation treatment is 200-5000.

40. The method of claim 39, wherein The gas-to-agent ratio of the passivation treatment is 500-3000.

41. The method according to any one of claims 12 to 15, wherein: In step (3), the forming agent comprises at least one of methyl cellulose, sesbania powder, cement and water; and / or, the lubricant comprises at least one of graphite, paraffin oil, ester lubricant, talc, stearic acid, palmitic acid, and metal or alkali metal salts of these acids; And / or, based on the total amount of the catalyst obtained after molding, the amount of the lubricant used is less than 3% by weight.

42. The method according to claim 41, wherein The promoter further comprises at least one noble metal.

43. The method according to claim 42, wherein The promoter further includes at least one of Pt, Pd, Ir, Rh, Ru and Os.

44. The method of claim 42, wherein: Based on the total amount of the hydrogenation catalyst, the content of the noble metal in terms of element is 0.005-0.05 wt %.

45. The method of claim 32, wherein The passivating agent for the liquid passivation is water or oil; And / or, the passivating agent for solid passivation is wax.

46. ​​A highly stable pre-reduction HPPO circulating methanol hydrogenation catalyst prepared by the method according to any one of claims 12 to 45.

47. Use of the high-stability pre-reduction HPPO cycle methanol hydrogenation catalyst according to any one of claims 1 to 11 and claim 46 in the purification of HPPO cycle methanol.

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