Preparation method of pre-reduction type hydrogenation catalyst containing nickel and zirconium

Abstract

The present invention relates to a pre-reduction type hydrogenation catalyst containing nickel and zirconium, comprising a heat-resistant inorganic oxide, an active component nickel and an auxiliary zirconium, based on the total amount of the catalyst, the nickel content in terms of oxide is 40-80% by weight, the zirconium content is 0.08-5% by weight, and the remainder is a heat-resistant inorganic oxide, wherein the heat-resistant inorganic oxide is aluminum oxide and / or silicon oxide; the number of active centers of the catalyst after re-reduction treatment is 0.12-0.6 mmol hydrogen / g catalyst, and the re-reduction treatment conditions include: a temperature of 200° C., a time of 2 hours, a re-reduction atmosphere of an atmosphere containing hydrogen and argon with a hydrogen concentration of 10% by volume, and a gas-to-agent ratio of 15000. The active centers provided by the present invention are abundant and easy to regenerate, and the catalyst has better reaction activity and stability.

Description

Technical Field

[0001] The invention belongs to the field of hydrogenation catalyst preparation, and specifically relates to a method for preparing a pre-reduction hydrogenation catalyst containing nickel and zirconium and a catalyst prepared by the method. Background Art

[0002] Metal catalysts have a wide range of applications. In synthetic ammonia, synthetic methanol, hydrocarbon steam reforming, methanation, hydrogenation, etc., due to the large space velocity, in order to reduce the pressure drop, the catalyst generally uses a larger particle size. Usually, the metal component of the catalyst is prepared in the form of oxides. Only by reducing the catalyst can it have catalytic activity. The quality of the catalyst reduction directly affects the performance of the catalyst.

[0003] Reasonable selection of reduction pretreatment conditions for the catalyst can make the catalyst have higher activity in the reaction. In addition, by introducing active metals and additives during the co-precipitation process, the active metals and additives can be distributed more evenly on the carrier and better exert their performance.

[0004] Catalyst reduction can be done by either pre-reduction or in-situ reduction. Pre-reduction can improve the utilization rate of reducing agents, reduce the amount of reducing agents, reduce the start-up costs, shorten the start-up cycle, and ultimately increase the economic benefits of the enterprise. For the same catalyst, different reduction and passivation treatment methods have different effects on the activity and selectivity of the reaction. Different catalysts usually use different reduction and passivation treatment methods to achieve better activity and selectivity.

[0005] During the reduction process, large-particle catalysts not only experience uneven reduction in different beds, but also within a single catalyst particle. In addition, during passivation, if the intense heat release cannot be removed in time, the degree of passivation may increase, and in severe cases, it may lead to high temperatures and metal sintering. From the perspective of mass transfer, heat transfer and reaction, the mass transfer and heat transfer rate of fine powders is significantly better than that of large particles, which can improve the diffusion conditions of the reaction, reduce the adverse effects of water on the reduction of metal catalysts during the reduction process, and remove the heat of the passivation process in time, making the degree of passivation more controllable.

[0006] The pre-reduction passivation method in the prior art takes a long time, so it is necessary to develop a pre-reduction method that is simple to operate, safe and reliable to pre-reduction the catalyst, and form a new reduction process that is fast, efficient, low in energy consumption and environmentally friendly. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention provides a pre-reduction hydrogenation catalyst containing zirconium and nickel and a preparation method thereof. The catalyst has good reactivation performance, multiple active centers, good stability, good industrial application prospects and is very suitable as a HPPO cycle methanol hydrogenation catalyst. Specifically, the present invention includes the following contents:

[0008] First, the present invention provides a pre-reduction hydrogenation catalyst containing nickel and zirconium, which contains a heat-resistant inorganic oxide, an active component nickel and an auxiliary zirconium. Based on the total amount of the catalyst, the nickel content in terms of oxide is 40-80% by weight, the zirconium content is 0.08-5% by weight, and the remainder is a heat-resistant inorganic oxide, wherein the heat-resistant inorganic oxide is aluminum oxide and / or silicon oxide; the number of active centers of the catalyst after re-reduction treatment is 0.12-0.6 mmol hydrogen / g catalyst, and the re-reduction treatment conditions include: a temperature of 200°C, a time of 2 hours, a re-reduction atmosphere of an atmosphere containing hydrogen and argon with a hydrogen concentration of 10 volume%, and a gas-to-agent ratio of 15000.

[0009] Secondly, the present invention provides a method for preparing the above catalyst, comprising the following steps:

[0010] (1) Preparing a catalyst intermediate: in the presence of a precipitant, a carrier precursor and an active component source are subjected to a coprecipitation reaction, and the obtained solid product is aged, washed, dried, and calcined to obtain a catalyst intermediate;

[0011] The carrier precursor is selected from at least one of silica sol, water glass, aluminum sol, sodium metaaluminate, aluminum nitrate, and aluminum chloride;

[0012] The active component source is at least one soluble salt of nickel and at least one soluble salt of zirconium;

[0013] The precipitant is selected from at least one of sodium carbonate, sodium aluminate, sodium bicarbonate, potassium carbonate, ammonia water and sodium hydroxide;

[0014] (2) treating the catalyst intermediate by any of the following methods (a) or (b) to obtain the pre-reduction hydrogenation catalyst; the amount of each raw material used is such that the nickel content of the final catalyst calculated as oxide is 40-80% by weight and the zirconium content is 0.08-5% by weight;

[0015] (a) crushing the catalyst intermediate of step (1) to obtain a solid product with a particle size of less than 2000 μm; and sequentially performing reduction treatment, passivation treatment and molding on the solid product:

[0016] (b) subjecting the catalyst intermediate of step (1) to molding, reduction treatment and passivation treatment in sequence to obtain the pre-reduction hydrogenation catalyst;

[0017] The reduction treatment and passivation treatment conditions in (a) and (b) may be the same or different, and are independently selected from the following conditions: the reduction treatment is carried out in the presence of a hydrogen-containing gas; the passivation treatment is carried out under the action of a passivating agent, and the passivation temperature is not higher than 140°C.

[0018] The soluble salt of nickel and the soluble salt of zirconium are at least one of their respective nitrates, organic acid salts, carbonates, chlorates, sulfates, acetates, chlorides and basic carbonates.

[0019] Finally, the present invention also provides a catalyst prepared according to the above method and its application in HPPO cycle methanol hydrogenation.

[0020] The preparation method of the catalyst provided by the present invention has sufficient and rapid reduction, mild passivation, high efficiency, and a catalyst that is very uniform and easy to regenerate and has many active centers after reshaping, and the stability of the catalyst is significantly improved. In the preferred reduction treatment and passivation treatment scheme of the present invention, the reduction and passivation effects are better, and the reaction activity and stability of the obtained catalyst are better. The addition of a zirconium additive can promote the reduction of the catalyst and is conducive to the dispersion of the metal. DETAILED DESCRIPTION

[0021] In order to allow those skilled in the art to better understand the present invention, the specific implementation of the invention is described in more detail below. The endpoints and any value of the scope disclosed in this article are not limited to this accurate scope or value, and these scopes or values ​​should be understood as containing values ​​close to these scopes or values. For numerical ranges, between the endpoint values ​​of each scope, between the endpoint values ​​of each scope and a separate point value, and between separate point values, one or more new numerical ranges can be combined with each other, and these numerical ranges should be considered as specifically disclosed in this article.

[0022] In the present invention, the gas-to-catalyst 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-catalyst ratio refers to the reducing gas (i.e., hydrogen-containing gas). In the gas passivation process, the gas in the gas-to-catalyst ratio refers to the passivating gas (i.e., oxygen-containing passivating gas, also called oxidizing gas).

[0023] According to the pre-reduction type hydrogenation catalyst provided by the present invention, if a noble metal is added therein, its performance can be greatly improved, for example, at least one noble metal additive selected from Pt, Pd, Ir, Rh and Ru can be added, preferably, based on the total amount of the hydrogenation catalyst, the content of the noble metal in terms of element is 0.005-0.05% by weight. In addition, the catalyst may also contain a molding agent and / or a lubricant introduced during the molding process. In the presence of these additives, the composition of each component in the catalyst is preferably: based on the total amount of the catalyst, the nickel content in terms of oxide is 45-75% by weight, the zirconium content is 0.12-4% by weight, and the total content of the molding agent and / or lubricant is 2-12% by weight.

[0024] The present invention has no restrictions on the molding agent and lubricant, and those skilled in the art can freely choose according to actual needs. Preferably, the molding 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, talcum powder, stearic acid and palmitic acid and metal or alkali metal salts of these acids.

[0025] Preferably, the molding agent comprises at least one of methyl cellulose, sesbania powder, cement and water, and the lubricant comprises at least one of graphite, paraffin oil, ester lubricant, talcum powder, stearic acid and palmitic acid and metal or alkali metal salts of these acids; further preferably, the particle size of the hydrogenation catalyst is 2-8 mm.

[0026] The present invention uses the number of active centers after re-reduction to represent the activity of the catalyst. The catalyst provided by the present invention has high re-reduction activity. In a preferred embodiment, the number of active centers of the hydrogenation catalyst after re-reduction treatment is 0.15-0.45 mmol hydrogen / g catalyst.

[0027] More preferably, according to TPR characterization, in the TPR curve of the catalyst, the temperature corresponding to the peak value of the low-temperature reduction peak with the largest area is 125-245°C.

[0028] The catalyst provided by the present invention has good regenerative properties, and can recover its activity by only being reduced under relatively low reduction treatment conditions, and has a large number of active centers. The pre-reduction type hydrogenation catalyst provided by the present invention has the characteristics of a large number of active centers and easy regeneration, and its stability is significantly improved, showing excellent circulating methanol purification performance, especially the addition of the auxiliary agent zirconium, which can not only promote the reduction of the catalyst, but also facilitate the dispersion of the metal, so that the catalyst has more active centers.

[0029] The present invention also provides a method for preparing the above-mentioned pre-reduction hydrogenation catalyst. The inventors have found that in the above-mentioned specific preparation method, on the one hand, the introduction of active metal nickel and auxiliary agent zirconium into the catalyst intermediate by coprecipitation can make the effective components more evenly distributed, better play the role of the effective components, and improve the performance of the catalyst; on the other hand, by subjecting the intermediate to specific reduction and passivation, it can be fully reduced, reducing the adverse effects of water on the metal, thereby improving the overall reaction activity and stability of the obtained catalyst.

[0030] The dosage of the precipitant in the present invention can be selected in a wide range, as long as the coprecipitation reaction can occur and a catalyst of a desired composition can be obtained. Those skilled in the art can select the dosage according to actual needs and the conventional dosage range.

[0031] Preferably, the molar ratio of the precipitant to the amount of the active component source calculated as a metal element and the total amount of the carrier precursor (such as aluminum) is (0.5-6): 1. In the present invention, the total amount of the active component source and the carrier precursor calculated as a metal element refers to the sum of the molar number of the active component source calculated as a metal element and the molar number of the carrier precursor calculated as a metal element.

[0032] 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, in which the concentration of sodium hydroxide 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 carrier 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 carrier precursor calculated as the metal element is (0.5-2):1.

[0033] Preferably, the conditions of the coprecipitation reaction 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, in a complete precipitation reaction, coprecipitation is stopped when pH=8.

[0034] The present invention does not limit the order and method of introducing the precipitant, carrier precursor and active component source, and those skilled in the art can freely choose, as long as the main catalyst precursor can be precipitated. Preferably, the coprecipitation method also includes the step of mixing the raw materials. The present invention does not limit the mixing method, for example, the precipitant can be added to the mixed salt solution containing the carrier precursor and the active component source, or the mixed salt solution containing the carrier precursor and the active component source can be added to the precipitant, or the two can be added in parallel; the former is preferred. The precipitant is preferably introduced in the form of an aqueous solution, and the aqueous solution is preferably always maintained at a constant temperature of 30-70°C. More preferably, the mixed salt solution is obtained by the following process configuration: first, a part of the carrier precursor (preferably in the form of an aqueous solution) and the active component source (preferably in the form of an aqueous solution) are mixed (preferably heated to 40-80°C at a stirring speed of 20-150 rpm) to obtain a metal salt mixed solution; then the metal salt mixed solution is mixed with the remaining carrier precursor (preferably in the form of an aqueous solution) (preferably stirred at a stirring speed of 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, and those skilled in the art can freely choose according to the needs.

[0035] 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.

[0036] In the present invention, there is no limitation on the washing after aging, for example, washing with deionized water, washing with water containing methanol and / or ethanol, and finally washing with water containing any one of glycerol, citric acid, formic acid and acetic acid. More preferably, washing is performed 2-6 times.

[0037] According to the present invention, the washing, drying and roasting in the preparation of the catalyst intermediate are conventional operations in the art unless otherwise specified. For example, the drying can be any one of ordinary drying, microwave drying, spray drying and flash drying, preferably spray drying. More preferably, the conditions for the spray drying include: an atomization pressure of 1-5MPa, an inlet temperature of 250-400°C, an outlet temperature of 80-160°C, and an atomization drying time of 2-5s. It is understood that the spray drying is carried out in a spray dryer, and the inlet temperature and outlet temperature are respectively the inlet temperature and outlet temperature of the spray dryer.

[0038] Under the most preferred conditions, the present invention adopts spray drying and the catalyst intermediate is treated by the above-mentioned method (a).

[0039] For the reduction treatment in step (2), (a) and (b) may be the same or different, and the reduction treatment is a single-stage reduction or a multi-stage reduction, preferably a single-stage reduction. The single-stage reduction process includes: maintaining a constant temperature at 100-600°C for 0.05-8 hours and a pressure of 0-2MPa; preferably, the single-stage reduction process also includes: heating to 100-600°C at a heating rate of 50-150°C / hour; the multi-stage reduction process includes: 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 insulation time in each stage is independently selected from 0.3-8 hours.

[0040] According to a preferred embodiment of the present invention, the multi-stage reduction process comprises: 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.

[0041] According to another preferred embodiment of the present invention, the multi-stage reduction process comprises: 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.

[0042] In a preferred embodiment of the present invention, the multi-stage reduction stage 2) includes: stage 2-1) heating to 320-380°C at a heating rate of 50-150°C / hour, and keeping warm for 0.5-6 hours; stage 2-2) heating to 420-490°C at a heating rate of 50-150°C / hour, and keeping warm for 0.3-4 hours. The present invention further adopts a two-stage temperature increase reduction method in stage 2) of the multi-stage reduction, on the one hand, the active metals in the catalyst are relatively fully reduced, the reduction degree of the catalyst is improved, and on the other hand, the heat conduction and diffusion are accelerated, reducing the adverse effects of water on the reduction.

[0043] 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 0-0.2MPa. It should be noted that the pressure is a gauge pressure.

[0044] In the present invention, preferably, the volume concentration of hydrogen in the hydrogen-containing gas is 50-90%, more preferably 55-80%.

[0045] 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.

[0046] Preferably, the gas-to-agent ratio in the reduction treatment is 200-5000.

[0047] In a specific embodiment, fluidized bed reduction is adopted, and preferably, the gas-to-agent ratio in the reduction treatment is 700-5000.

[0048] In another specific embodiment, non-fluidized bed reduction is adopted, and preferably, the gas-to-agent ratio is 200-2000, and more preferably 500-1500.

[0049] According to the present invention, the main equipment for the reduction treatment is a reduction furnace, and the reducing gas (i.e., the hydrogen-containing gas) can be passed 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 procedure 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 N 2 Replacement system to ensure the system is clean and stable. 2 The volume percentage is ≤0.5%, start the compressor, maintain the system pressure at 0.0-2MPa (gauge pressure), and perform reduction according to the heating and hydrogen preparation procedures. In the above 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, then enters the heating furnace for further heating, and then enters the reactor for reduction. After the remaining gas comes out from the bottom of the reactor, it enters the heat exchanger to exchange heat with the cold supplementary reducing gas for cooling. Then the water inlet condenser is cooled to 50°C and enters the water separator. After the reduced water is separated, it is compressed by the circulating compressor and dried by the molecular sieve dryer, and then circulated back to the pre-reduction reactor to continue to participate in the reduction, saving a lot of reducing gas.

[0050] In step (2) of the present invention, preferably, the passivation treatment comprises 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.

[0051] Preferably, the passivation treatment adopts gas passivation, liquid passivation or solid passivation, and more preferably adopts gas passivation.

[0052] 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 is controlled not to exceed 120°C during the passivation process.

[0053] Preferably, the passivating agent of the liquid passivation is water or oil, etc. In the liquid passivation, those skilled in the art can select the amount of the passivating agent according to actual needs, as long as the desired passivation effect can be achieved.

[0054] Preferably, the passivating agent of the solid passivation is wax, etc. In the solid passivation, those skilled in the art can select the amount of the passivating agent according to actual needs, as long as the desired passivation effect can be achieved.

[0055] According to one embodiment of the present invention, the main equipment used for the passivation treatment is a passivation furnace. The reduction furnace and the passivation furnace can be configured separately or share one. When the reduction and passivation use the same equipment, it is preferred to introduce a protective gas after the reduction to replace the hydrogen in the system, and then perform the passivation. During the passivation process, it is preferred to ensure that the passivation temperature reaches the desired range by adjusting the amount of protective gas (preferably carbon dioxide) pumped in. The passivation gas can be passed once or the gas can be recycled, preferably the gas is recycled. By optimizing the passivation cooling rate and improving the passivation efficiency, the efficiency of the entire system is improved. After the catalyst reduction is completed, in the passivation furnace, passivation is carried out by carbon dioxide or a mixed gas of carbon dioxide and nitrogen or air. The temperature in the passivation furnace is controlled below 140°C, and the gas after passivation is recycled or directly discharged.

[0056] According to one embodiment of the present invention, the passivation is performed by gas passivation. The reduced catalyst is moved into a passivation reactor. Passivation step: replace the H in the system with carbon dioxide or carbon dioxide and nitrogen. 2 , rapid cooling. 2 When the volume percentage of the reactor is ≤1%, and the temperature in the reactor is below 140°C, O 2 , using multi-stage passivation. By adjusting the amount of carbon dioxide pumped in, the temperature in the reactor is ensured not to exceed 140°C, preferably not to exceed 120°C.

[0057] In a preferred embodiment of the present invention, the method further comprises: in step (2), cooling the catalyst obtained after the reduction treatment to below 100°C, preferably below 80°C, further preferably below 50°C, introducing a low-concentration oxidizing gas below 100°C, preferably below 80°C, for passivation, wherein the oxygen concentration is 0.01-21%; the oxygen concentration of the oxidizing gas is continuously increased.

[0058] 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 increased after being stably introduced for a certain period of time. 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 that in the previous stage. In another specific embodiment, the oxygen concentrations in the first few stages are the same and lower than that in the subsequent stages, thereby showing an overall upward trend.

[0059] 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 2-fold continuous increase, 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 in the first stage, the oxygen concentration in the third stage is 1.2 times that in the second stage, and the oxygen concentration in the fourth stage is 2 times that in the third stage.

[0060] 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.

[0061] According to the present invention, preferably, during the passivation process, the oxygen concentration of the oxidizing gas is continuously increased in at least 3 stages. It is understandable 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. Further, it is understandable that the relative multiples of the oxygen concentration of the oxidizing gas in each of two adjacent stages can be independently the same or different, for example, the relative multiples of the oxygen concentration of the oxidizing gas in the first stage and the second stage are 1.5, and the relative multiples of the oxygen concentration of the oxidizing gas in the second stage and the third stage can be 1.5 or 2.

[0062] In a specific preferred embodiment, the passivation treatment is preferably carried out in at least 3 stages, more preferably in 3-12 stages, for example, the number of stages can be any point value among 4, 5, 6, 7, 8, 9, 10, 11, and 12, more preferably in 4-9 stages, and the oxygen concentration in the oxidizing gas increases step by step. The preferred embodiment of the present invention can make the catalyst passivated more uniformly, so that the catalyst is easier to be reactivated by reduction and has more active centers.

[0063] In a specific preferred embodiment, the passivation treatment is divided into three stages, the oxygen concentration of the first stage is 0.01%-0.2%, the oxygen concentration of the second stage is 0.2-1%, and the oxygen concentration of the third stage is 1-21%. Preferably, the passivation treatment time is allocated as the ratio of the first passivation stage: the second passivation stage: the third passivation stage (4-9): (0.5-1): (0.5-1).

[0064] In the present invention, there is no limitation on the method of 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 with a protective gas, and then performing the passivation.

[0065] According to a preferred embodiment of the present invention, in the passivation treatment, the initial oxygen concentration of the oxidizing gas introduced is 0.01-0.1 volume %, preferably 0.02-0.1 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 easy to re-reduce.

[0066] According to a preferred embodiment of the present invention, 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 previous stage. Under this preferred embodiment, the catalyst can be passivated more uniformly and controllably, so that the obtained catalyst has more reduction active centers after re-reduction treatment, and the passivation efficiency is high. In the present invention, preferably, in the passivation process, the concentration of the oxidizing gas introduced in the last stage is 21% by volume, that is, air is introduced.

[0067] In the present invention, when the reactor has no temperature rise and the oxygen contents at the inlet and outlet are substantially the same, the passivation operation is terminated. According to actual conditions, the total passivation time of the passivation treatment of the present invention is generally 0.3-40 hours. The passivation time in the pre-reduction method of the prior art is generally more than 48 hours.

[0068] According to the present invention, preferably, the gas-to-agent ratio of the passivation treatment is 200-5000, more preferably 500-3000, for example, any point value among 500, 1000, 1200, 1500, 2000, 3000 and any point value and range therebetween.

[0069] According to the present invention, preferably, during the passivation process, the gas-to-agent ratio in the first stage is not lower than that in the second stage. This preferred solution is more conducive to promoting a uniform passivation process of the catalyst and improving the passivation efficiency.

[0070] The present invention has no special restrictions on molding, and the optional range of the molding agent and lubricant is the same as the aforementioned selection, which will not be repeated here. The present invention has no restrictions on the amount of the lubricant, and those skilled in the art can freely choose according to needs. Preferably, the amount of the lubricant is less than 3% by weight based on the total amount of the catalyst obtained after molding. Preferably, the co-catalyst also includes at least one of the precious metals, and the selection of the precious metal element is the same as described in the catalyst. Preferably, the amount of the precious metal element is such that in the prepared catalyst, the content of the precious metal in terms of element is 0.005-0.05% by weight based on the total amount of the hydrogenation catalyst.

[0071] In the molding process of the present invention, those skilled in the art may also choose whether to add other additives according to actual needs, such as a molding agent, and the molding may be 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 selection for the amount of the molding agent, as long as molding is possible, and those skilled in the art may make an adaptable selection according to actual conditions.

[0072] The present invention also provides a pre-reduction hydrogenation catalyst prepared according to the above method and the use of the catalyst in HPPO circulating methanol purification. Preferably, the method of application comprises: re-reducing the catalyst at 150-250° C. for 2-24 hours under a hydrogen-containing atmosphere; and then performing a hydrogenation purification treatment on the raw material under circulating methanol purification reaction conditions.

[0073] The technical solution of the present invention is further described below according to specific embodiments. The protection scope of the present invention is not limited to the following embodiments, which are listed only for illustrative purposes and do not limit the present invention in any way.

[0074] In the embodiment of the present invention, a laser particle size analyzer is used to measure the particle size of the powdered catalyst. The model of the laser particle size analyzer is Malvern Laser Particle Size Analyzer Mastersizer 2000. The result is recorded as follows: the particle size Dv(90) is 100 microns, indicating that 90% of the particles are smaller than 100 microns.

[0075] TPR is used to characterize the regenerative performance of the catalyst. Specifically, the maximum temperature corresponding to the low-temperature reduction peak in the TPR spectrum curve is used as an indicator to evaluate the regenerative performance of the passivated catalyst. The lower the maximum temperature of the low-temperature reduction peak, the easier the catalyst is to regenerate. The test method for the reduction degree is: first test the TPR spectrum curve of 0.2g of the pre-reduced catalyst; then calcine 0.2g of the pre-reduced catalyst in an air atmosphere at 450°C for 2h to obtain an oxidized catalyst, and test the TPR spectrum curve of the oxidized catalyst according to the same TPR test method, wherein the temperature corresponding to the peak of the low-temperature reduction peak with the largest area in the TPR spectrum curve is the re-reduction temperature of the sample. The reduction degree of the pre-reduced catalyst is calculated by the TPR spectrum curve, and the 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%.

[0076] The number of active centers was characterized by TPD. The number of active centers was measured on an Autochem 2950 fully automatic high-pressure chemical adsorption instrument produced by Micromeritics, USA. 2 Programmed temperature desorption (TPD) 2 -TPD) test, the test method is: weigh 0.2000g of 40-60 mesh sample, first perform re-reduction activation, the re-reduction conditions are: hydrogen content of 10 volume % H 2 -Ar mixed gas, the mixed gas flow rate was 50mL / min, and the temperature was raised to 200℃ at a heating rate of 10℃ / min for 2h. The reduced catalyst was heated to 10% by volume in H 2 -Ar mixed gas, and when the temperature dropped to 55°C, switch to Ar gas for purging at an Ar flow rate of 20 mL / min until the baseline was stable, and then perform H 2 -TPD experiment. 2 -TPD experimental conditions and procedures are as follows: carrier gas is Ar, carrier gas flow rate is 20 mL / min, heating rate is 10 °C / min, final temperature is 400 °C, thermal conductivity detector (TCD) detects the signal, and obtains the TPD curve.

[0077] Example 1

[0078] Preparation of catalyst intermediate: 194 g of Ni(NO 3 ) 2 6H 2 O, 25.2g of Al(NO 3 ) 3 9H 2 O, 0.56 g Zr(NO 3 ) 4·5H2O was dissolved in 500ml of deionized water to prepare a mixed metal salt solution. The alkaline solution I was kept at a constant temperature of 50°C. 89.3g of silica sol GS-30 (silicon oxide concentration is 30% by weight) was added to 100g of clean water and stirred at a speed of 50r / min. The metal salt solution and silica sol were mixed at a speed of 50r / min and stirred evenly. This became the base solution I for preparing the catalyst. Then 115g of Na 2 CO 3 Dissolve in 500ml of deionized water to prepare alkaline solution II, maintain alkaline solution II at a constant temperature of 50℃, gradually add mixed salt solution II to alkaline solution I, and stir continuously for complete precipitation reaction, with PH=8 as the titration end point, stir evenly and age at 50℃ for 2 hours, wash the precipitated precursor three times with deionized water; slurry the filter cake, solid content 35% by weight, stir for 1.5 hours, and transport the above slurry to a spray dryer, the atomization pressure of the spray dryer is 2.5MPa, the inlet temperature of the spray dryer is 330℃, the outlet temperature is 130℃, and it flows out from the outlet of the spray dryer after 4s to obtain microsphere particles with a particle size DV90 of 154 microns. Then roast at 370℃ for 3h. The powder composition, in terms of metal oxide by mass percentage, includes: NiO: 62.1%; Al 2 O 3 :4.3%;SiO 2 :33.4%;ZrO 2 : 0.2%.

[0079] The catalyst intermediate is reduced, passivated and formed: the calcined powder is transported to a fluidized bed reduction system, a nitrogen replacement system is first introduced into the reactor until the oxygen content is qualified (oxygen content ≤ 0.5 volume %), and then a 60 volume % hydrogen-nitrogen mixed gas is obtained by hydrogen supplementation, and the 60 volume % hydrogen-nitrogen mixed gas is preheated by controlling the opening of the preheating furnace to raise the catalyst bed to 400°C at 100°C / hour for reduction for 2h, the pressure is 0.2MPa, and the gas-to-agent ratio is 2000.

[0080] Then, nitrogen is introduced to replace hydrogen in the system, and the reduced catalyst is cooled to below 55°C, and an oxygen-containing gas with an oxygen concentration of 0.2-21% by volume, which is composed of air and nitrogen, is introduced at a normal pressure below 55°C, and the gas-to-agent ratio is 2000. The oxygen-containing gas with oxygen concentrations of 0.2%, 0.6%, 1.0%, 3.0%, 8.0% and 21% by volume is introduced in 6 stages, wherein after the oxygen-containing gas of the previous stage is introduced, when the oxygen concentration at the gas outlet is equal to the oxygen concentration at the gas inlet, the oxygen-containing gas of the next stage is introduced, and the oxygen concentration is gradually increased for passivation until the passivation is completed. During this period, the passivation temperature of the catalyst bed is controlled to be less than 80°C, and the passivation time is 2h.

[0081] The passivated powder, calcium aluminate cement and graphite were weighed and mixed evenly in a ratio of 90:8:2, and then pressed into a 4×4 mm cylindrical catalyst product to obtain a pre-reduction hydrogenation catalyst C1. The catalyst was characterized by reduction degree, TPR and TPD. The characterization results and reduction degree are shown in Table 1.

[0082] Example 2

[0083] Compared with Example 1, the only difference is the reduction conditions: the temperature is increased from 120°C / hour to 410°C for 2h, 70% by volume of hydrogen-nitrogen mixed gas, and the gas-to-agent ratio is 2500. A pre-reduction type hydrogenation catalyst C2 is obtained.

[0084] Example 3

[0085] Compared with Example 1, the only difference is that the reduction passivation conditions are different, specifically:

[0086] The dried powder obtained in step 1 of Example 1 is conveyed to a fluidized bed reduction reactor. A nitrogen replacement system is first introduced into the reactor until the oxygen content is qualified (oxygen content ≤ 0.5 volume %), and then a 70 volume % hydrogen-nitrogen mixed gas is obtained by hydrogen supplementation. The 70 volume % hydrogen-nitrogen mixed gas is preheated by controlling the opening of the preheating furnace to raise the catalyst bed to 420° C. at 100° C. / hour for reduction for 1 hour, the pressure is 0.2 MPa, and the gas-to-agent ratio is 2500.

[0087] Then, nitrogen is introduced to replace hydrogen in the system, and the reduced catalyst is cooled to below 55°C, and an oxygen-containing gas with an oxygen concentration of 0.1-21% by volume composed of air and nitrogen is introduced at below 55°C under normal pressure. The gas-to-agent ratio is 2000, and oxygen-containing gases with oxygen concentrations of 0.1%, 0.2%, 0.6%, 1.0%, 3.0%, 8.0% and 21% by volume are introduced in 7 stages in sequence, wherein after the oxygen-containing gas of the previous stage is introduced, when the oxygen concentration at the gas outlet is equal to the oxygen concentration at the gas inlet, the oxygen-containing gas of the next stage is introduced, and the oxygen concentration is gradually increased for passivation until the passivation is completed. During this period, the passivation temperature of the catalyst bed is controlled to be less than 70°C, and the passivation time is 2h, to obtain a pre-reduction hydrogenation catalyst C3.

[0088] Example 4

[0089] Compared with Example 1, the difference is:

[0090] 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 h and then crushed to a particle size of 700 μm (DV(90)). After being calcined at 400° C. for 4 h, the reduction passivation of Example 1 was performed. The reduction conditions were different in that the filter cake was reduced at 400° C. for 4 h in a 40% by volume hydrogen and nitrogen mixed atmosphere. The filter cake was then cooled to 55° C. and passivated in Example 1. During the process, the passivation temperature of the catalyst bed was controlled to be less than 80° C.

[0091] Then, the molding of Example 1 was carried out, except that the catalyst was pressed into round tablets with a particle size of 5×5 mm to obtain the pre-reduction type hydrogenation catalyst C4.

[0092] Example 5

[0093] Compared with Example 1, the composition of the bottom solution I during the coprecipitation process is different, specifically: 190g of Ni(NO 3 ) 2 6H 2 O, 400g of Al(NO 3 ) 3 9H 2 O, 5g of Zr(NO 3 ) 4 ·5H 2 O was dissolved in 500ml of deionized water to prepare a mixed metal salt solution, and the alkaline solution I was kept at a constant temperature of 50°C; 60g of silica sol GS-30 (silicon oxide concentration is 30% by weight) was added to 100g of clean water, and stirred at a speed of 50r / min. The metal salt solution and silica sol solution were mixed at a stirring speed of 50r / min and stirred evenly to obtain base solution I. Then 120g of Na 2 CO 3 Dissolved in 500 ml of deionized water to prepare alkaline solution II, and the rest was treated as in Example 1 to finally obtain pre-reduction hydrogenation catalyst C5. The powder composition, in terms of metal oxide content by mass percentage, includes: NiO: 66.2%; Al 2 O 3 :7.4%;SiO 2 :24.4%;ZrO 2 : 2.0%.

[0094] 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.

[0095] Example 6

[0096] Compared with Example 1, the only difference is that after the catalyst intermediate is obtained in step 1, the catalyst intermediate is first molded, and then subjected to reduction and passivation treatment steps. Specifically:

[0097] Preparation of catalyst intermediate: microsphere particles with a particle size DV(90) of 154 μm were prepared according to Example 1 and calcined at 400° C. to obtain a catalyst intermediate;

[0098] The catalyst intermediate is molded, reduced and passivated: the catalyst intermediate, calcium aluminate cement and graphite are weighed and mixed evenly in a ratio of 90:8:2, and then pressed into a 4×4 mm cylinder. The cylindrical molded body is then transported to a fluidized bed reduction reactor for reduction and passivation under the same conditions as in Example 1 to obtain a pre-reduced hydrogenation catalyst C6.

[0099] Table 1

[0100] Example catalyst Re-reduction temperature, ℃ Reduction degree, % Number of active centers, mmol hydrogen / g catalyst 1 C1 176 82 0.27 2 C2 178 87 0.28 3 C3 172 88 0.29 4 C4 175 81 0.22 5 C5 175 82 0.26 6 C6 212 71 0.22

[0101] Test Case

[0102] The reaction performance of the pre-reduced catalyst obtained in the above examples and comparative examples in HPPO cyclic methanol hydrogenation was evaluated in a fixed bed reactor. The catalyst dosage was 10 mL and the mesh size was 40-60 mesh.

[0103] The catalyst needs to be reduced before use. Reduction conditions: pressure is normal pressure, the reducing gas is a hydrogen-nitrogen mixture with a hydrogen concentration of 70% by volume, the gas-to-agent ratio is 1000, the reduction temperature is 200°C, and the reduction time is 2h. Then, at a temperature of 60°C, a pressure of 2.0MPa, and a raw material liquid hourly space velocity of 8.5h -1 、V(H 2 The catalyst performance was evaluated under the condition of ) / V(raw material) of 500, wherein the raw material was recycled methanol (methanol content was 85 volume %), the acetaldehyde mass concentration in the raw material was 1500 ppm, and hydrogen peroxide (H 2 O 2 ) mass concentration is 5000ppm. The results are listed in Table 2.

[0104] Table 2

[0105] Example catalyst Acetaldehyde conversion rate, % Conversion rate 90% stable time, h 7 C1 97 560 8 C2 98 563 9 C3 98 578 10 C4 96 515 11 C5 98 546 12 C6 96 510

[0106] Note: The conversion rate 90% stable time refers to the time when the acetaldehyde conversion rate remains at 90% without decreasing.

[0107] The results in Table 2 show that the pre-reduction catalyst of the present invention has good reaction performance and stability in HPPO circulating methanol purification.

[0108] The catalyst pre-reduction and passivation treatment process of the present invention is simple to operate, has mild conditions, and has a good passivation effect. The surface layer of the catalyst treated by the present invention is oxidized to form a dense oxide film, which prevents the air from deeply oxidizing the inside of the catalyst, is convenient for storage and transportation, and can be directly started when used. During the reaction, the oxide film is easily oxidized by H in the raw gas. 2 The reduction and re-reduction temperature is lower and the reduction degree is high. It can quickly show higher catalytic activity and selectivity, which is better than the activity and selectivity of the in-situ reduced catalyst, greatly shortens the start-up time, and has a significant effect.

[0109] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A pre-reduction hydrogenation catalyst containing nickel and zirconium, comprising a heat-resistant inorganic oxide, an active component nickel and an auxiliary zirconium, wherein the nickel content calculated as oxide is 40-80% by weight, the zirconium content calculated as oxide is 0.08-5% by weight, and the balance is a heat-resistant inorganic oxide, wherein the heat-resistant inorganic oxide is aluminum oxide and / or silicon oxide; the particle size of the hydrogenation catalyst is 2-8 mm; The number of active centers of the catalyst after the re-reduction treatment is 0.12-0.6 mmol hydrogen / g catalyst, and the re-reduction treatment conditions include: temperature of 200° C., time of 2 hours, re-reduction atmosphere of an atmosphere containing hydrogen and argon with a hydrogen concentration of 10% by volume, and a gas-to-agent ratio of 15000; The preparation method of the pre-reduction type hydrogenation catalyst comprises: (1) Preparing a catalyst intermediate: In the presence of a precipitant, a carrier precursor and an active component source are subjected to a co-precipitation reaction, and the obtained solid product is aged, washed, dried, and calcined to obtain a catalyst intermediate; The carrier precursor is selected from at least one of silica sol, water glass, aluminum sol, sodium metaaluminate, aluminum nitrate, and aluminum chloride; The active component source is at least one soluble salt of nickel and at least one soluble salt of zirconium; The precipitant is selected from at least one of sodium carbonate, sodium aluminate, sodium bicarbonate, potassium carbonate, ammonia water and sodium hydroxide; (2) treating the catalyst intermediate by any of the following methods (a) or (b) to obtain the pre-reduction hydrogenation catalyst; the amount of each raw material used is such that the nickel content in the final catalyst calculated as oxide is 40-80% by weight, and the zirconium content in the final catalyst calculated as oxide is 0.08-0.5% by weight; (a) crushing the catalyst intermediate of step (1) to obtain a solid product with a particle size of less than 2000 μm; and sequentially performing reduction treatment, passivation treatment and molding on the solid product: (b) subjecting the catalyst intermediate of step (1) to molding, reduction treatment and passivation treatment in sequence to obtain the pre-reduction hydrogenation catalyst; The reduction treatment and passivation treatment conditions in (a) and (b) are the same or different and are independently selected from the following conditions: the reduction treatment is carried out in the presence of a hydrogen-containing gas; the passivation treatment is carried out under the action of a passivating agent, and the passivation temperature is not higher than 140°C; The passivation treatment adopts gas passivation and is carried out in at least three stages. The passivating agent of the 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 oxygen concentration in the oxidizing gas increases continuously from stage to stage. During the passivation process, the initial oxygen concentration of the oxidizing gas introduced is 0.01-0.1 volume %.

2. The catalyst according to claim 1, wherein The catalyst further contains a precious metal additive, and the precious metal additive is at least one selected from Pt, Pd, Ir, Rh and Ru.

3. The catalyst according to claim 2, 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% by weight.

4. The catalyst according to claim 3, wherein The catalyst also includes a molding agent and / or a lubricant. Based on the total amount of the catalyst, the nickel content calculated as oxide is 45-75% by weight, the zirconium content calculated as oxide is 0.12-4% by weight, and the total content of the molding agent and / or lubricant is 2-12% by weight.

5. The catalyst according to claim 4, wherein The molding 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, talcum powder, stearic acid and palmitic acid and metal or alkali metal salts of these acids.

6. The catalyst according to claim 1, wherein The number of active centers of the hydrogenation catalyst after re-reduction treatment is 0.15-0.45 mmol hydrogen / g catalyst.

7. The catalyst according to claim 6, wherein According to TPR characterization, in the TPR curve of the catalyst, the temperature corresponding to the peak value of the low-temperature reduction peak with the largest area is 125-245°C.

8. The catalyst according to claim 1, wherein The molar ratio of the amount 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; The conditions of the coprecipitation reaction include: the reaction temperature is 30-70°C, and the pH when the coprecipitation reaction is completed is 7-9; The aging conditions include: an aging temperature of 30-70° C. and an aging time of 1-8 hours.

9. The catalyst according to claim 1, wherein The reduction treatment is single-stage reduction or 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.

10. The catalyst according to claim 9, wherein The single-stage reduction process also includes: heating to 100-600°C at a heating rate of 50-150°C / hour; the multi-stage reduction process includes: gradually increasing the reaction temperature at a heating rate of 60-150°C / hour and keeping warm for a period of time in each stage, wherein the reduction temperature in the first stage is 160-300°C, the reduction temperature in the last stage is 320-520°C, and the keeping warm time in each stage is independently selected from 0.3-8 hours.

11. The catalyst according to claim 1, wherein The passivation treatment comprises 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.

12. The catalyst according to claim 1, wherein The passivation treatment is carried out in 3-12 stages, and the gas-to-agent ratio of the passivation treatment is 200-5000.

13. The catalyst according to claim 12, wherein The passivation treatment is carried out in 4-9 stages, and the gas-to-agent ratio of the passivation treatment is 500-3000.

14. The catalyst according to claim 1, wherein During the passivation process, the initial oxygen concentration of the oxidizing gas introduced is 0.02-0.1% by volume; During the passivation process, 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.

15. The catalyst according to claim 1, wherein The molding process includes the step of introducing a precious metal additive, wherein the precious metal additive is at least one selected from Pt, Pd, Ir, Rh and Ru.

16. The catalyst according to claim 15, 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% by weight.

17. The catalyst according to any one of claims 1 to 16, wherein 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 are the same reactor or different reactors; the reduction reactor and the passivation reactor are independently selected from a rotary kiln reactor, a fluidized bed reactor, and a drum reactor.