Passivation method for nickel-based hydrogenation catalyst, passivated nickel-based hydrogenation catalyst, and catalytic hydrogenation method

Abstract

The invention relates to the technical field of hydrogenation catalysts, in particular to a passivation method of a nickel hydrogenation catalyst, a passivation type nickel hydrogenation catalyst and a catalytic hydrogenation method. The passivation method of the nickel-based hydrogenation catalyst comprises the following steps: carrying out reduction treatment on the nickel-based hydrogenation catalyst by adopting hydrogen to prepare a pre-reduced nickel-based hydrogenation catalyst; carrying out first passivation treatment on the pre-reduced nickel hydrogenation catalyst by adopting first gas, forming a precursor layer on the surface of the pre-reduced nickel hydrogenation catalyst, and preparing an intermediate; the first gas comprises water vapor, and the airspeed of the first gas is 80 h <-1 >-120 h <-1 >; and carrying out second passivation treatment on the intermediate by adopting second gas to convert the precursor layer into a nickel oxide protective layer so as to prepare the passivation type nickel hydrogenation catalyst, the second gas includes oxygen. According to the passivation method, the passivation process is safe and controllable, the passivated nickel oxide layer structure is easy to reduce and activate at low temperature, and the catalytic activity expression of the nickel hydrogenation catalyst is improved.

Description

Technical Field

[0001] This application relates to the field of hydrogenation catalyst technology, specifically to a passivation method for nickel-based hydrogenation catalysts, a passivated nickel-based hydrogenation catalyst, and a catalytic hydrogenation method. Background Technology

[0002] In the field of hydrogenation reaction, nickel-based catalysts have significant advantages such as excellent activity adaptability, good selectivity for target reactions, abundant and low-cost nickel raw material reserves, and mature and stable preparation processes. They can efficiently achieve the hydrogenation conversion of unsaturated functional groups such as olefins, aromatics, and nitro groups under mild to moderate reaction conditions. This has led to the widespread application of nickel-based catalysts in many fields such as petrochemicals and fine chemicals.

[0003] However, nickel-based catalysts contain catalytically active metallic nickel, which is extremely chemically reactive. Once exposed to air, the active metallic nickel components on their surface are prone to rapid oxidation and release a large amount of heat. This not only causes irreversible loss of catalyst active sites and leads to a significant decrease in catalytic performance, but may also cause local overheating or even combustion due to violent exothermic reactions, seriously restricting the safety and convenience of their storage, transportation and on-site use.

[0004] To address the aforementioned issues, traditional techniques employ trace amounts of oxygen for passivation of reduced nickel-based catalysts. While this approach partially restores catalyst activity through reduction, it suffers from several drawbacks: firstly, some nickel-based active components may form stable oxidized structures after passivation, making complete activation through reduction difficult and leading to decreased catalyst activity; secondly, direct oxygen introduction during passivation can cause localized exothermic oxidation, potentially triggering the aggregation and growth of nickel grains, reducing the dispersion of active sites and consequently affecting the catalyst's catalytic activity and selectivity for the target reaction. Therefore, developing a method that ensures the safety of the passivation process while maximizing the preservation of active catalyst sites is crucial for enhancing the industrial application value of nickel-based catalysts. Summary of the Invention

[0005] Based on this, this application provides a passivation method for nickel-based hydrogenation catalysts, a passivated nickel-based hydrogenation catalyst, and a catalytic hydrogenation method. The passivation method of this application is safe and controllable, and can achieve uniform passivation and protective coating of the active components on the surface of the reduced nickel-based catalyst. The passivated nickel oxide layer structure is easily reduced and activated at low temperatures, which is beneficial to improving the catalytic activity expression of the nickel-based hydrogenation catalyst.

[0006] A first aspect of this application provides a passivation method for a nickel-based hydrogenation catalyst, comprising the following steps:

[0007] A pre-reduced nickel-based hydrogenation catalyst was prepared by reducing the nickel-based hydrogenation catalyst with hydrogen gas.

[0008] The pre-reduced nickel-based hydrogenation catalyst is subjected to a first passivation treatment using a first gas to form a precursor layer on its surface, thereby preparing an intermediate. The first gas comprises water vapor and has a gas space velocity of 80 h⁻¹. -1 ~120h -1 ;

[0009] The intermediate is subjected to a second passivation treatment using a second gas, which transforms the precursor layer into a nickel oxide protective layer, thereby preparing a passivated nickel-based hydrogenation catalyst; the second gas includes oxygen.

[0010] In some embodiments, the preparation steps of the pre-reduced nickel-based hydrogenation catalyst include:

[0011] With hydrogen purity ≥90% and hydrogen space velocity 50h⁻¹ -1 ~100h -1 The nickel-based hydrogenation catalyst was reduced at 450℃~550℃, and the water vapor concentration in the reaction tail gas was detected to be ≤100ppm, thus preparing the pre-reduced nickel-based hydrogenation catalyst.

[0012] In some embodiments, the first gas comprises, by volume fraction, 99% to 99.9% of the first inert gas and 0.1% to 1% of the water vapor.

[0013] In some embodiments, the step of performing a first passivation treatment on the pre-reduced nickel-based hydrogenation catalyst using a first gas includes:

[0014] The pre-reduced nickel-based hydrogenation catalyst was cooled to 60°C to 120°C at a cooling rate of 5°C / min to 10°C / min, with the first gas space velocity at 80 h⁻¹. -1 ~120h -1 The pre-reduced nickel-based hydrogenation catalyst is subjected to a first passivation treatment of 0.8h~1.2h under the condition of temperature rise ≤3℃. After the equilibrium of the first passivation treatment is detected, the intermediate is prepared.

[0015] The step of detecting the equilibrium of the first passivation treatment includes: increasing the flow rate of the first gas by 5 mL / min to 15 mL / min, performing the first passivation treatment for 25 min to 35 min each time, and when the temperature rise of the catalyst is ≤1℃, the first passivation treatment is considered to be in equilibrium.

[0016] In some embodiments, the second gas comprises, by volume fraction, 99% to 99.9% of the second inert gas and 0.1% to 1% of the oxygen.

[0017] In some embodiments, the step of performing a second passivation treatment on the intermediate using a second gas includes:

[0018] The intermediate is heated to 120°C to 150°C at a heating rate of 2°C / min to 5°C / min, while the second gas space velocity is 80 h⁻¹. -1 ~120h -1 The intermediate is subjected to a second passivation treatment for 0.8h to 1.2h under the condition that the temperature rise is ≤3℃. After the equilibrium of the second passivation treatment is detected, the passivated nickel-based hydrogenation catalyst is prepared.

[0019] The step of detecting the equilibrium of the second passivation treatment includes: increasing the flow rate of the second gas by 5 mL / min to 15 mL / min, performing the second passivation treatment for 25 min to 35 min each time, and when the temperature rise of the catalyst is ≤1℃, the second passivation treatment is considered to be in equilibrium.

[0020] In some embodiments, the nickel-based hydrogenation catalyst has a particle size of 2 mm to 3 mm.

[0021] In some embodiments, the nickel-based hydrogenation catalyst includes a support and an active component supported on the support, the active component comprising nickel. The nickel content in the nickel-based hydrogenation catalyst is 8% to 15% by mass.

[0022] A second aspect of this application provides a passivated nickel-based hydrogenation catalyst, which is prepared by any of the preparation methods described in the first aspect of this application.

[0023] A third aspect of this application provides a catalytic hydrogenation method, comprising the following steps: activating the passivated nickel-based hydrogenation catalyst described in the second aspect of this application, and then subjecting the catalytic reactants to a hydrogenation reaction.

[0024] The activation process parameters for the passivated nickel-based hydrogenation catalyst include: hydrogen purity ≥ 90% and hydrogen space velocity of 90 h⁻¹. -1 ~110h -1 The activation temperature is 200℃~260℃.

[0025] In some embodiments, the process parameters for catalytic hydrogenation of the reactants include: a feed space velocity of 1 h⁻¹ for the reactants. -1 ~6h -1 The reaction temperature is 120℃~180℃ and the reaction pressure is 2MPa~4MPa.

[0026] The passivation method for nickel-based hydrogenation catalysts provided in this application has at least the following advantages:

[0027] The passivation method for nickel-based hydrogenation catalysts provided in this application first employs hydrogen reduction treatment, which fully reduces the unactivated nickel components in the catalyst to catalytically active metallic nickel, thus laying the foundation for the first and second passivation treatments. Further, a first passivation treatment is performed synergistically with a first gas containing water vapor. This step utilizes the mild oxidation of water vapor to form a dense precursor layer at the active nickel sites on the surface of the pre-reduced nickel-based hydrogenation catalyst, avoiding the problems of localized severe oxidation and nickel grain aggregation caused by direct oxygen introduction. A second passivation treatment is then performed using a second gas containing oxygen, in which the catalytic precursor layer is transformed into a denser and more stable nickel oxide protective layer. Therefore, in the passivation method provided in this application, the reduction reaction, the first passivation reaction, and the second passivation reaction work synergistically to form a controllable thickness and dense oxide protective layer on the catalyst surface. This protective layer effectively isolates the active nickel components inside the catalyst from air, preventing oxidative deactivation, and can also be rapidly reduced and removed at a relatively low temperature, restoring the catalyst's activity.

[0028] Therefore, the passivation method of this application is safe and controllable. It can achieve uniform passivation and protective coating of the active components on the surface of the reduced nickel catalyst. Moreover, the passivated nickel oxide layer structure is easily reduced and activated at low temperature, which is beneficial to improving the catalytic activity expression of the nickel hydrogenation catalyst. Attached Figure Description

[0029] Figure 1 This is a scanning electron microscope image of the passivated nickel-based hydrogenation catalyst prepared in Example 1 of this application;

[0030] Figure 2 TPR analysis was performed on the passivated nickel-based hydrogenation catalyst in Example 1 and Comparative Example 1 of this application, as well as the newly prepared reduced non-passivated nickel-based hydrogenation catalyst, to obtain hydrogen absorption spectra. Detailed Implementation

[0031] The passivation method for nickel-based hydrogenation catalysts, passivated nickel-based hydrogenation catalysts, and catalytic hydrogenation methods of this application are further described in detail below with reference to specific embodiments. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0032] In this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0033] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Unless otherwise stated or in case of conflict, the terms or phrases used herein have the following meanings:

[0035] In this application, the terms "multiple", "various", "multiple times", "multi-dimensional", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more or more.

[0036] In this application, the terms "first aspect," "second aspect," "third aspect," and "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," and "fourth," etc., serve only a non-exhaustive enumeration purpose and should be understood not to constitute a closed limitation on quantity.

[0037] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0038] In this application, the terms "combinations thereof", "any combination thereof", and "any combination thereof" include all suitable combinations of any two or more of the listed items.

[0039] In this application, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0040] In this application, terms such as "preferred," "better," "more suitable," and "ideal" are used only to describe implementation methods or embodiments with better effects, and should be understood not to constitute a limitation on the scope of protection of this application.

[0041] In this application, terms such as "further," "even further," and "particularly" are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0042] In this application, the terms "optionally," "optionally," and "optional" refer to options that are optional, meaning they can be selected from either "with" or "without." If multiple "optional" options appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" option is independent.

[0043] In this application, numerical intervals (i.e., numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the aforementioned numerical intervals are considered continuous and include the two endpoints (i.e., the minimum and maximum values) of the numerical range, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints. In this document, this is equivalent to directly listing every integer. For example, if t is an integer selected from 1 to 10, it means that t is any integer selected from the group of integers consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Furthermore, when multiple ranges are provided to describe features or characteristics, these ranges can be merged. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0044] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0045] In this application, percentage content refers to mass percentage for solid-liquid mixtures and solid-phase-solid mixtures, and volume percentage for liquid-phase-liquid mixtures, unless otherwise specified.

[0046] In this application, unless otherwise specified, percentage concentrations refer to final concentrations. The final concentration refers to the percentage of the added component in the system after its addition.

[0047] In this application, "space velocity" refers to the volume of gas passing through a unit mass of catalyst per unit time (under standard conditions), and the unit is h. -1 It reflects the contact efficiency between the gas and the catalyst.

[0048] In this application, "temperature rise" refers to the temperature increase of the catalyst bed during the reaction process, which is caused by the exothermic reaction and is a direct indicator for judging the reaction rate and intensity.

[0049] In this application, "activity recovery" refers to the ratio of the catalytic activity of the catalyst after passivation and activation treatment to the catalytic activity of a freshly prepared reduced, unpassivated catalyst. It reflects the degree of influence of the passivation process on the catalyst activity (measured by the degree of reduction at 300°C under a pure hydrogen atmosphere).

[0050] In the field of toluene hydrogenation, non-precious metal catalysts such as nickel-based catalysts have become one of the core catalyst types that the industry focuses on and researches due to their significantly lower preparation costs. However, nickel-based catalysts have the following drawbacks: the catalytically active metallic nickel in nickel-based catalysts is chemically reactive and readily reacts with oxygen in the air, releasing a large amount of heat. This not only causes irreversible loss of active sites, leading to a significant decline in catalytic performance, but may also trigger localized overheating or even combustion, seriously affecting the safety of catalyst storage, transportation, and on-site use. To protect the active sites in nickel-based catalysts, related technologies often involve oxidation or protective treatment of the catalysts, followed by reactivation treatment before the hydrogenation process.

[0051] Currently, the main steps for oxidizing nickel catalysts are as follows: (1) Directly treating the catalyst with oxygen. Although this method can partially restore the catalyst activity through the reduction process, a large number of active sites are still lost. (2) The reduced nickel catalyst is stored by liquid immersion in organic substances such as kerosene and paraffin. However, the organic substances after immersion are difficult to remove. Moreover, for tubular reactors, it is difficult to pack the catalyst after liquid immersion. (3) Coating the surface of the reduced nickel catalyst with an organic protective film such as polyethylene glycol or organosiloxane can also isolate it from the air. During activation, the organic coating is decomposed and removed by heating (e.g., 200℃~250℃) to restore the catalyst activity. However, the organic coating is prone to softening and falling off due to temperature changes (e.g., high temperature environment) during storage, resulting in protection failure. In addition, a small amount of carbon residue may be generated during the decomposition of the coating, which adheres to the catalyst surface, blocks the active sites, and causes a decrease in catalyst activity (the activity recovery rate is usually only about 80%). At the same time, the decomposition products may cause slight pollution to the toluene hydrogenation reaction products, affecting the purity of the products. (4) The reduced catalyst is cooled to 60℃~70℃, and a low concentration of ammonia gas is introduced to form a nickel-ammonia complex protective layer on the catalyst surface. When it is reactivated after storage, the complex is decomposed by heating (280℃~300℃), releasing ammonia gas and restoring active Ni. However, ammonia gas has an irritating odor and poses a potential health risk to operators. Ammonia gas leakage may also cause environmental pollution. Industrial production requires a complex waste gas treatment system, which increases equipment investment and operating costs. At the same time, nickel-ammonia complex is prone to hydrolysis in high humidity environments, which leads to the failure of the protective layer. It has strict requirements for the humidity of the storage environment (relative humidity ≤40%) and poor adaptability.

[0052] In addition, for the reduction process, there is a method to directly reduce the catalyst in situ using a hydrogenation reactor. However, since the hydrogenation reaction of toluene itself requires a low temperature, conventional reactor and heating module designs only need to meet the operating temperature of 300°C. In situ reduction requires increasing the reactor's heating and heat resistance to 500°C, which is not conducive to industrial application.

[0053] Therefore, developing a passivation method for nickel-based hydrogenation catalysts that balances activation safety, catalyst performance stability, and economic viability for industrial applications is of great significance for promoting their large-scale application in toluene hydrogenation processes.

[0054] Based on this, the first aspect of this application provides a passivation method for a nickel-based hydrogenation catalyst, comprising the following steps:

[0055] S10: A pre-reduced nickel-based hydrogenation catalyst is prepared by reducing the nickel-based hydrogenation catalyst with hydrogen.

[0056] S20: A first passivation treatment is performed on the pre-reduced nickel-based hydrogenation catalyst using a first gas to form a precursor layer on the surface of the catalyst, thus preparing an intermediate. The first gas includes water vapor, and the first gas space velocity is 80 h⁻¹. -1 ~120h -1 .

[0057] S30: A second passivation treatment is performed on the intermediate using a second gas, transforming the precursor layer into a nickel oxide protective layer to prepare a passivated nickel-based hydrogenation catalyst. The second gas includes oxygen.

[0058] The passivation method for nickel-based hydrogenation catalysts provided in this application first employs hydrogen reduction treatment, which fully reduces the unactivated nickel components in the catalyst to catalytically active metallic nickel, thus laying the foundation for the first and second passivation treatments. Further, a first passivation treatment is performed synergistically with a first gas containing water vapor. This step utilizes the mild oxidation of water vapor to form a dense precursor layer at the active nickel sites on the surface of the pre-reduced nickel-based hydrogenation catalyst, avoiding the problems of localized severe oxidation and nickel grain aggregation caused by direct oxygen introduction. A second passivation treatment is then performed using a second gas containing oxygen, in which the catalytic precursor layer is transformed into a denser and more stable nickel oxide protective layer. Therefore, in the passivation method provided in this application, the reduction reaction, the first passivation reaction, and the second passivation reaction work synergistically to form a controllable thickness and dense oxide protective layer on the catalyst surface. This protective layer effectively isolates the active nickel components inside the catalyst from air, preventing oxidative deactivation, and can be rapidly reduced and removed at a relatively low temperature (200℃~260℃), restoring the catalyst's activity. Furthermore, the reduction and activation temperature is compatible with the temperature required for the hydrogenation reaction of toluene, which helps to reduce equipment manufacturing costs, operating energy consumption and subsequent maintenance costs, and improve the economic efficiency of the process.

[0059] The passivation method of this application is safe and controllable. It can achieve uniform passivation and protective coating of active components on the surface of reduced nickel catalysts. Furthermore, the passivated nickel oxide layer structure is easily reduced and activated at low temperatures, which is beneficial to improving the catalytic activity expression of nickel hydrogenation catalysts.

[0060] In some of these examples, in step S10, the nickel-based hydrogenation catalyst has a particle size of 2 mm to 3 mm.

[0061] In some examples, the nickel-based hydrogenation catalyst includes a support and an active component supported on the support, the active component being nickel. The mass fraction of nickel in the nickel-based hydrogenation catalyst is 8%–15%. Further examples include, but are not limited to, one or more of alumina, silica, and titanium oxide. The specific surface area of ​​the support is 150 m². 2 / g~300m 2 / g. The pore size of the carrier is 0.5 cm³.3 / g~1.2cm 3 / g.

[0062] In this application, the nickel-based hydrogenation catalyst is a non-noble metal nickel-based catalyst, wherein the Ni component is mainly supported on the support in the form of Ni and / or NiO. This structural feature provides a suitable surface environment for the reduction of the Ni component and the formation of the nickel oxide protective layer.

[0063] In some of these examples, step S10, the preparation step of the pre-reduced nickel-based hydrogenation catalyst includes:

[0064] With hydrogen purity ≥90% and hydrogen space velocity 50h⁻¹ -1 ~100h -1 The nickel-based hydrogenation catalyst was reduced at 450℃~550℃, and the water vapor concentration in the reaction tail gas was measured to be ≤100ppm to prepare a pre-reduced nickel-based hydrogenation catalyst. Furthermore, the reduction reaction time was 1h~4h.

[0065] After reduction treatment, the unactivated Ni components such as NiO and Ni(OH)2 in the nickel-based hydrogenation catalyst can be fully reduced to catalytically active metallic Ni. This lays the foundation for the subsequent first and second passivation treatment processes, and helps the catalyst to quickly restore high activity when it is reactivated after passivation.

[0066] Further, in step S10, the purity of the hydrogen gas is 90%~100%. Preferably, the purity of the hydrogen gas is ≥99.99%. Using high-purity hydrogen gas can avoid side reactions between impurity gases and the catalyst, and prevent byproducts from affecting catalytic activity. The hydrogen space velocity includes, but is not limited to, 50 h⁻¹. -1 55h -1 60h -1 65h -1 70h -1 75h -1 80h -1 85h -1 90h -1 95h -1 or 100h -1The reduction temperature is within the range defined by any two of the above points as endpoints. The reduction treatment temperature includes, but is not limited to, 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃, 540℃, or 550℃, or any two of the above points as endpoints. Limiting the reduction treatment temperature to the above range allows for sufficient reduction of metallic Ni while avoiding damage to the nickel-based hydrogenation catalyst support structure caused by high temperatures. Since hydrogen mainly reacts with oxygen, the termination of the reduction reaction can be determined by the water vapor concentration in the tail gas. For example, a water vapor concentration ≤100ppm in the reaction tail gas indicates that the unactivated Ni component has been sufficiently reduced.

[0067] In some examples, in step S20, the first gas comprises, by volume fraction, 99% to 99.9% of a first inert gas and 0.1% to 1% of water vapor. For example, the first inert gas includes, but is not limited to, nitrogen and argon. The first inert gas, acting as a carrier gas, dilutes the water vapor concentration and controls the oxidation reaction rate; the water vapor, acting as an oxidant, has mild oxidizing properties and can form a uniform precursor layer on the surface of the nickel-based hydrogenation catalyst. Limiting the volume fraction of water vapor to 0.1% to 1% avoids the problems of over-oxidation due to slightly higher concentrations and limited precursor layer formation due to slightly lower concentrations. For example, the volume fraction of the first inert gas includes, but is not limited to, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9%, or any two of the above values ​​as endpoints. The volume fraction of water vapor includes, but is not limited to, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%, or any two of the above point values ​​as endpoints.

[0068] In some examples, step S20, which involves performing a first passivation treatment on the pre-reduced nickel-based hydrogenation catalyst using a first gas, includes:

[0069] The pre-reduced nickel-based hydrogenation catalyst was cooled to 60°C–120°C at a cooling rate of 5°C / min–10°C / min, with a first gas space velocity of 80 h⁻¹. -1 ~120h -1 The pre-reduced nickel-based hydrogenation catalyst was subjected to a first passivation treatment of 0.8h~1.2h under the condition of temperature rise ≤3℃. After the equilibrium of the first passivation treatment was detected, an intermediate was prepared.

[0070] The step of detecting the equilibrium of the first passivation treatment includes: increasing the flow rate of the first gas by 5 mL / min to 15 mL / min, performing the first passivation treatment for 25 min to 35 min each time, and when the temperature rise of the catalyst is ≤1℃, the first passivation treatment is considered to be in equilibrium.

[0071] After the reduction treatment in step S10, the temperature is lowered to 60℃~120℃ at a cooling rate of 5℃ / min~10℃ / min to avoid rapid cooling causing catalyst particle breakage and structural damage. For example, the cooling rate includes, but is not limited to, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, or 10℃ / min, or any two of the above values ​​as endpoints. The temperature after cooling includes, but is not limited to, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, or 120℃, or any two of the above values ​​as endpoints.

[0072] The space velocity of the first gas includes, but is not limited to, 80 h⁻¹. -1 90h -1 100h -1 110h -1 or 120h -1 , or the range formed by any two of the above point values ​​as endpoint values.

[0073] In the first passivation treatment step of 0.8h~1.2h under the condition that the temperature rise of the pre-reduced nickel-based hydrogenation catalyst is ≤3℃, since the pre-reduced nickel-based hydrogenation catalyst is placed on the catalyst bed, the temperature rise can be judged by monitoring the temperature of the catalyst bed. Furthermore, during the first passivation treatment in step S20, since the oxidation reaction of water vapor and active nickel is exothermic, an excessively high bed temperature indicates that the oxidation reaction is too rapid, which can easily lead to localized over-oxidation. Therefore, this application preferably performs the first passivation treatment under the condition that the temperature rise of the pre-reduced nickel-based hydrogenation catalyst is ≤3℃.

[0074] After the first passivation treatment, the steps to check the equilibrium of the first passivation treatment include: increasing the flow rate of the first gas by 5 mL / min to 15 mL / min, performing the first passivation treatment for 25 min to 35 min each time, and when the temperature rise of the catalyst is ≤1℃, the first passivation treatment is considered to be in equilibrium.

[0075] Understandably, after the initial flow rate stabilizes for 0.8h to 1.2h of the first passivation treatment, the mixed gas flow rate can be gradually increased (by 5mL / min to 15mL / min each time, and further by 5mL / min to 10mL / min each time). After each increase, the flow rate should be stabilized for 25min to 35min. If the temperature rise of the catalyst bed stabilizes within 1℃, it indicates that a stable precursor layer has been formed on the catalyst surface, the first passivation treatment has reached equilibrium, and the second passivation treatment stage can begin.

[0076] In step S20, water vapor and nickel in the pre-reduced nickel-based hydrogenation catalyst undergo a mild oxidation reaction, which avoids excessive oxidation of metallic nickel and initially forms a thin and uniform oxide precursor layer on the catalyst surface, laying the foundation for the formation of a nickel oxide-rich protective coating layer in the second passivation treatment.

[0077] In some examples, in step S30, the second gas comprises, by volume fraction, 99% to 99.9% of a second inert gas and 0.1% to 1% of oxygen. Oxygen, as a strong oxidant, reacts with the precursor layer and residual active nickel to form a dense nickel oxide layer; wherein the volume fraction of oxygen is controlled at 0.1% to 1%, this avoids an overly vigorous oxidation reaction and prevents the nickel oxide-containing protective layer from developing pores due to excessive exothermic reaction, thereby affecting catalytic activity. For example, the second inert gas includes, but is not limited to, nitrogen and argon. The volume fraction of the second inert gas includes, but is not limited to, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, or 99.8%, or any two of the above values ​​as endpoints. The volume fraction of oxygen includes, but is not limited to, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%, or any two of the above point values ​​as endpoints within a range.

[0078] In some of these examples, the step of using a second gas to perform a second passivation treatment on the intermediate includes:

[0079] The intermediate was heated to 120°C to 150°C at a heating rate of 2°C / min to 5°C / min, with a second gas space velocity of 80 h⁻¹. -1 ~120h -1 A second passivation treatment of 0.8h to 1.2h was carried out under the condition that the intermediate temperature rise was ≤3℃. After the equilibrium of the second passivation treatment was detected, a passivated nickel-based hydrogenation catalyst was prepared.

[0080] The step of detecting the equilibrium of the second passivation treatment includes: increasing the flow rate of the second gas by 5 mL / min to 15 mL / min, performing the second passivation treatment for 25 min to 35 min each time, and when the temperature rise of the catalyst is ≤1℃, the second passivation treatment is considered to be in equilibrium.

[0081] Heating the intermediate to 120°C-150°C at a rate of 2°C / min to 5°C / min avoids rapid temperature rise that could cause cracking of the precursor layer and affect the density of the protective layer. For example, the heating rate may include, but is not limited to, 2°C / min, 3°C / min, 4°C / min, or 5°C / min, or any two of these values ​​as endpoints. The temperature after heating may include, but is not limited to, 120°C, 130°C, 140°C, or 150°C, or any two of these values ​​as endpoints. As mentioned earlier, the catalyst is placed on a catalyst bed, so the temperature rise can be determined by monitoring the temperature of the catalyst bed. Furthermore, during the second passivation treatment in step S30, controlling the intermediate to undergo the second passivation treatment under a temperature rise ≤3°C avoids local overheating and stabilizes the oxidation reaction rate. Understandably, if the temperature rise is >3°C, the temperature rise can be controlled by adjusting process parameters such as gas flow rate during the passivation treatment.

[0082] The steps for determining the equilibrium of the second passivation treatment include: increasing the flow rate of the second gas by 5 mL / min to 15 mL / min, performing the second passivation treatment for 25 min to 35 min, and then determining the equilibrium of the second passivation treatment when the temperature rise of the catalyst is ≤1℃.

[0083] Understandably, after the initial flow rate stabilizes for 0.8h to 1.2h for the second passivation treatment, the mixed gas flow rate can be gradually increased (by 5mL / min to 15mL / min each time, and further by 5mL / min to 10mL / min each time). After each increase, the flow rate should be stabilized for 25min to 35min. If the temperature rise of the catalyst bed stabilizes within 1℃, it indicates that a complete and dense nickel oxide protective layer has been formed on the catalyst surface. At this point, the second passivation treatment stage reaches equilibrium, and a passivated nickel-based hydrogenation catalyst is prepared.

[0084] During the second passivation process, oxygen reacts with the nickel in the precursor layer and the residual active metallic nickel inside, further replenishing and forming a dense nickel oxide protective layer. This nickel oxide protective layer isolates the air and is easily removed in subsequent reduction and activation steps. For example, the thickness of the nickel oxide protective layer is 5 nm to 10 nm.

[0085] The passivation method of this application controls the temperatures of the reduction treatment, the first passivation treatment, and the second passivation treatment. The temperatures of each stage work synergistically to ensure sufficient reduction of the nickel component, avoiding uneven thickness or over-oxidation of the nickel oxide protective layer, thus preventing impact on catalyst performance. Furthermore, the synergistic interaction of the first and second gases, as well as the process parameters of the first and second passivation treatments, ensures a gentle and uniform oxidation reaction through catalyst bed temperature rise. The equilibrium judgment criteria for each step ensure the completeness of the reaction at each stage, preventing incomplete formation of the final nickel oxide-containing protective layer that could lead to catalyst oxidation during storage.

[0086] Furthermore, the passivation method of this application can form a uniform and dense oxide protective layer on the catalyst surface. This oxide protective layer can isolate the contact between air and active nickel components. During reactivation, the protective layer can be quickly removed at low temperature, and the activity recovery rate can stably reach more than 95%.

[0087] A second aspect of this application provides a passivated nickel-based hydrogenation catalyst, which is prepared by any of the preparation methods described in the first aspect of this application.

[0088] Since the catalytically active metallic nickel in the passivated nickel-based hydrogenation catalyst prepared in this application has been passivated, the passivated nickel-based hydrogenation catalyst can be stored and transported in an air environment without the need for protection by inert gases or organic solvents. Furthermore, the reduction and activation of this passivated nickel-based hydrogenation catalyst is relatively simple, and its catalytic performance can be easily restored.

[0089] For example, conventionally prepared passivated nickel-based hydrogenation catalysts undergo further oxidation after 12 hours of exposure to air, leading to a further decrease in the degree of re-reduction (after 120 hours at 60% humidity and 25°C, the activity recovery rate drops from 70% to 50%). The passivated nickel-based hydrogenation catalyst of this application has a nickel oxide protective layer on its surface, exhibiting excellent oxidation resistance. Testing shows that it can be stably stored for more than 30 days in an air environment (temperature 0°C~40°C, relative humidity 10%-60%), during which time the activity recovery rate after re-reduction is not significantly reduced. This significantly reduces the time cost and operational difficulty of catalyst storage and inter-plant transport, making it more suitable for the logistics and inventory management needs of large-scale industrial production.

[0090] For example, the activation process parameters for passivated nickel-based hydrogenation catalysts include: hydrogen purity ≥ 90% and hydrogen space velocity of 90 h⁻¹. -1 ~110h -1 The activation temperature is 200℃~260℃.

[0091] A third aspect of this application provides a catalytic hydrogenation method, comprising the following steps: activating a passivated nickel-based hydrogenation catalyst according to the second aspect of this application, followed by hydrogenation of the catalytic reactants.

[0092] The activation process parameters for the passivated nickel-based hydrogenation catalyst include: hydrogen purity ≥ 90% and hydrogen space velocity of 90 h⁻¹. -1 ~110h -1 The activation temperature is 200℃~260℃. For example, the purity of the hydrogen is 90%~100%. Preferably, the purity of the hydrogen is ≥99.99%. The hydrogen space velocity is, but is not limited to, 90 h⁻¹. -1 100h -1 or 110h -1 The activation temperature is within the range defined by any two of the above point values ​​as endpoints. The activation temperature includes, but is not limited to, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, or 260℃, or the range defined by any two of the above point values ​​as endpoints. Further, the step of determining the equilibrium of the activation treatment includes: detecting that the water vapor concentration in the reaction tail gas is ≤100ppm.

[0093] The passivated nickel-based hydrogenation catalyst prepared in this application can be reduced and activated at a relatively low temperature, making it suitable for toluene hydrogenation reactors; and the metallic nickel formed after reduction has high catalytic performance, with a difference of ≤5% compared to freshly reduced, unpassivated catalysts.

[0094] Preferably, the reactant is toluene. This application has found that the passivated nickel-based hydrogenation catalyst prepared by the above method is particularly suitable for the hydrogenation of toluene to prepare methylcyclohexane. The toluene hydrogenation reaction is mainly used to convert unsaturated bonds in toluene into saturated bonds. This reaction requires a high number and dispersion of active sites on the catalyst. If the active Ni component of the catalyst is oxidized or the active sites are blocked, the conversion rate and the selectivity of the target product will be significantly reduced.

[0095] In some of these examples, the process parameters for the hydrogenation reaction of the catalytic reactants include: a feed space velocity of 1 h⁻¹. -1 ~6h -1 The reaction temperature is 120℃~180℃ and the reaction pressure is 2MPa~4MPa.

[0096] The following detailed embodiments illustrate this application in more detail. It should also be understood that the following embodiments are for further explanation only and should not be construed as limiting the scope of protection of this application. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of this application fall within the scope of protection of this application. The specific process parameters, etc., in the following embodiments are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the range based on the description herein, and are not necessarily limited to the specific values ​​in the embodiments below.

[0097] Example 1

[0098] Passivation method for nickel-based hydrogenation catalysts: The nickel-based hydrogenation catalyst has a particle size of 2mm~3mm and includes a support and an active component supported on the support. The active component, nickel, has a mass fraction of 10% in the nickel-based hydrogenation catalyst, and the support is alumina. The loading amount of the nickel-based hydrogenation catalyst is 100g.

[0099] (1) Reduction treatment: with hydrogen purity ≥ 99.99% and hydrogen space velocity 100 h⁻¹ -1 Under certain conditions, the nickel-based hydrogenation catalyst was reduced at 500℃ for 2 hours, and the water vapor concentration in the reaction tail gas was detected to be ≤100ppm, thus preparing a pre-reduced nickel-based hydrogenation catalyst.

[0100] (2) First passivation treatment: The pre-reduced nickel-based hydrogenation catalyst is cooled to 80°C at a cooling rate of 5~10°C / min, and the initial space velocity of the first gas (including nitrogen with a volume fraction of 99.5% and water vapor with a volume fraction of 0.5%) is 100 h⁻¹. -1 The pre-reduced nickel-based hydrogenation catalyst bed was subjected to a first passivation treatment for 1 hour under a temperature rise of 0.5℃. The equilibrium of the first passivation treatment was detected by the following steps: the flow rate of the first gas was increased by 5~10 mL / min until the gas space velocity reached 150 h⁻¹. -1 After each 30-minute passivation treatment, the temperature rise of the catalyst stabilizes at 1°C, the first passivation treatment reaches equilibrium, and an intermediate is prepared.

[0101] (3) Second passivation treatment: The intermediate is heated to 120°C at a heating rate of 2~5°C / min, and the second gas (including nitrogen with a volume fraction of 99.9% and oxygen with a volume fraction of 0.1%) is switched, with an initial space velocity of 100 h⁻¹. -1 The intermediate bed was subjected to a second passivation treatment for 1 hour under a temperature rise of 2.2℃. The equilibrium of the second passivation treatment was detected by the following steps: the flow rate of the second gas was increased by 5~10 mL / min until the gas space velocity reached 150 h⁻¹. -1 After each 30-minute passivation treatment, the temperature rise of the catalyst stabilized at 0.6℃. The second passivation treatment reached equilibrium, thus preparing a passivated nickel-based hydrogenation catalyst.

[0102] Catalytic hydrogenation method for toluene: A passivated nickel-based hydrogenation catalyst is used in a hydrogen gas environment with a purity ≥ 99.99% and a hydrogen space velocity of 100 h⁻¹. -1 The toluene was activated at 250℃ for 1 hour, followed by catalytic hydrogenation of toluene to prepare methylcyclohexane. The process parameters for the hydrogenation reaction included a toluene feed space velocity of 5 h⁻¹. -1 The reaction temperature is 150℃ and the reaction pressure is 3MPa.

[0103] After the reaction was completed, the conversion rate of toluene was 98.5%, and the selectivity of the target product was 99.2%.

[0104] Example 2

[0105] The passivation method for nickel-based hydrogenation catalysts is basically the same as in Example 1, except that the temperature of the first passivation treatment in Example 2 is 60°C.

[0106] Catalytic hydrogenation of toluene: Same as in Example 1. After the reaction, the conversion rate of toluene was 98.6%, and the selectivity of the target product was 99.3%.

[0107] Example 3

[0108] The passivation method for nickel-based hydrogenation catalysts is basically the same as in Example 1, except that the temperature of the first passivation treatment in Example 3 is 120°C.

[0109] Catalytic hydrogenation of toluene: Same as in Example 1. After the reaction, the conversion rate of toluene was 98.1%, and the selectivity of the target product was 99.0%.

[0110] Example 4

[0111] The passivation method for nickel-based hydrogenation catalysts is basically the same as in Example 1, except that the temperature of the second passivation treatment in Example 4 is 130°C.

[0112] Catalytic hydrogenation of toluene: Same as in Example 1. After the reaction, the conversion rate of toluene was 97.9%, and the selectivity of the target product was 99.4%.

[0113] Example 5

[0114] The passivation method for nickel-based hydrogenation catalysts is basically the same as in Example 1, except that the temperature of the second passivation treatment in Example 5 is 150°C.

[0115] Catalytic hydrogenation of toluene: Same as in Example 1. After the reaction, the conversion rate of toluene was 98.2%, and the selectivity of the target product was 99.3%.

[0116] Example 6

[0117] The passivation method for nickel-based hydrogenation catalysts is basically the same as in Example 1, except that the volume fraction of water vapor in the first gas is 0.1% and the volume fraction of nitrogen is 99.9%.

[0118] Catalytic hydrogenation of benzene: Same as in Example 1. After the reaction, the conversion rate of toluene was 91.4%, and the selectivity of the target product was 99.0%.

[0119] Example 7

[0120] The passivation method for nickel-based hydrogenation catalysts is basically the same as in Example 1, except that the volume fraction of water vapor in the first gas is 1.5% and the volume fraction of nitrogen is 98.5%.

[0121] Catalytic hydrogenation of benzene: Same as in Example 1. After the reaction, the conversion rate of toluene was 92.0%, and the selectivity of the target product was 98.1%.

[0122] Examples 6 and 7 demonstrate that the volume fraction of water vapor in the first passivation gas needs to be strictly controlled.

[0123] Comparative Example 1

[0124] Passivation method for nickel-based hydrogenation catalysts: The nickel-based hydrogenation catalyst has a particle size of 2mm~3mm and includes a support and an active component supported on the support. The active component, nickel, has a mass fraction of 10% in the nickel-based hydrogenation catalyst, and the support is alumina. The loading amount of the nickel-based hydrogenation catalyst is 100g.

[0125] (1) Reduction treatment: with hydrogen purity ≥ 99.99% and hydrogen space velocity 100 h⁻¹ -1 Under certain conditions, the nickel-based hydrogenation catalyst was reduced at 500℃ for 2 hours, and the water vapor concentration in the reaction tail gas was detected to be ≤100ppm, thus preparing a pre-reduced nickel-based hydrogenation catalyst.

[0126] (2) Passivation treatment: The pre-reduced nickel-based hydrogenation catalyst was cooled to 80°C and a mixed gas (including 97% nitrogen and 3% oxygen by volume) was introduced at an initial space velocity of 100 h⁻¹. -1 The catalyst bed was subjected to a passivation treatment for 1 hour under a temperature rise of 2°C. The passivation equilibrium was detected by the following steps: the gas space velocity was increased by 5-10 mL / min until it reached 150 h⁻¹. -1 After each 30-minute passivation treatment, the temperature rise of the catalyst stabilized at 0.6℃, indicating that the passivation treatment was in equilibrium, thus preparing a passivated nickel-based hydrogenation catalyst.

[0127] Catalytic hydrogenation method for toluene: A passivated nickel-based hydrogenation catalyst is used in a hydrogen gas environment with a purity ≥ 99.99% and a hydrogen space velocity of 10 h⁻¹.-1 The toluene was activated at 500℃ for 2 hours, followed by catalytic hydrogenation of toluene to prepare methylcyclohexane. The process parameters for the hydrogenation reaction included a toluene feed space velocity of 4 h⁻¹. -1 The reaction temperature is 150℃ and the reaction pressure is 3MPa.

[0128] After the reaction, the conversion rate of toluene was 95.3%, and the selectivity for the target product was 98.6%. Additionally, the toluene space velocity was changed to 5 h⁻¹. -1 At this point, the conversion rate was only 82%.

[0129] As can be seen from Comparative Example 1, the passivation method provided in this application provides a more superior catalytic performance after the catalyst is reduced and activated following passivation.

[0130] Comparative Example 2

[0131] Passivation method for nickel-based hydrogenation catalysts: The nickel-based hydrogenation catalyst has a particle size of 2mm~3mm and includes a support and an active component supported on the support. The active component, nickel, has a mass fraction of 10% in the nickel-based hydrogenation catalyst, and the support is alumina. The loading amount of the nickel-based hydrogenation catalyst is 100g.

[0132] (1) Reduction treatment: with hydrogen purity ≥ 99.99% and hydrogen space velocity 100 h⁻¹ -1 Under certain conditions, the nickel-based hydrogenation catalyst was reduced at 500℃ for 2 hours, and the water vapor concentration in the reaction tail gas was measured to be ≤100ppm to prepare a pre-reduced nickel-based hydrogenation catalyst. After the reduction was completed, the temperature was lowered to below 40℃ at a rate of 5℃ / min to obtain the catalyst intermediate.

[0133] (2) Kerosene impregnation: 99.9% pure industrial-grade kerosene was sprayed onto the catalyst bed from top to bottom using a constant flow pump at a rate of 10 mL / min for 30 min to ensure that a uniform oil film was formed on the surface of each catalyst particle. Subsequently, nitrogen gas (99.99% pure) was introduced to purge the bed, and the nitrogen space velocity was controlled at 50 h⁻¹. -1 Remove excess free kerosene while retaining the adsorbed oil film.

[0134] (3) Storage and transportation: Pack the catalyst from step (2) into bags and store it by nitrogen replacement.

[0135] Catalytic hydrogenation method for toluene: The above catalyst is heated in nitrogen gas with a purity ≥99.99% and a nitrogen space velocity of 10 h⁻¹. -1Under the given conditions, the temperature was increased to 120°C at a rate of 10°C / min, then switched to a hydrogen atmosphere with the same flow rate, and the temperature was further increased to 200°C for approximately 10 hours, ending when no CH compounds were detected in the tail gas. Subsequently, toluene was catalytically hydrogenated to prepare methylcyclohexane. The process parameters for the hydrogenation reaction included a toluene feed space velocity of 5 h⁻¹. -1 The reaction temperature is 150℃ and the reaction pressure is 3MPa.

[0136] After the reaction, the conversion rate of toluene was 94.2%, and the selectivity of the target product was 98.5%. Furthermore, kerosene residue was found in the product 48 hours before the reaction. Comparative Example 2 also shows that the passivation method provided in this application provides superior catalytic performance after catalyst reduction and activation following passivation.

[0137] Comparative Example 3

[0138] Passivation method for nickel-based hydrogenation catalysts: The nickel-based hydrogenation catalyst has a particle size of 2mm~3mm and includes a support and an active component supported on the support. The active component, nickel, has a mass fraction of 10% in the nickel-based hydrogenation catalyst, and the support is alumina. The loading amount of the nickel-based hydrogenation catalyst is 100g.

[0139] (1) Reduction treatment: with hydrogen purity ≥ 99.99% and hydrogen space velocity 100 h⁻¹ -1 Under certain conditions, the nickel-based hydrogenation catalyst was reduced at 500℃ for 2 hours, and the water vapor concentration in the reaction tail gas was detected to be ≤100ppm, thus preparing a pre-reduced nickel-based hydrogenation catalyst.

[0140] (2) First passivation treatment: The pre-reduced nickel-based hydrogenation catalyst is cooled to 80°C at a cooling rate of 5~10°C / min, and the initial space velocity of the first gas (including 60% carbon dioxide and 40% nitrogen by volume) is 100 h⁻¹. -1 The pre-reduced nickel-based hydrogenation catalyst bed was subjected to a first passivation treatment for 10 hours under the condition of a temperature rise of 0.5℃.

[0141] (3) Second passivation treatment: The intermediate is heated to 120°C at a heating rate of 2~5°C / min, and the second gas (including nitrogen with a volume fraction of 99.9% and oxygen with a volume fraction of 0.1%) is switched, with an initial space velocity of 100 h⁻¹. -1 The intermediate bed was subjected to a second passivation treatment for 1 hour under a temperature rise of 2.2℃. The equilibrium of the second passivation treatment was detected by the following steps: the flow rate of the second gas was increased by 5~10 mL / min until the gas space velocity reached 150 h⁻¹. -1 After each 30-minute passivation treatment, the temperature rise of the catalyst stabilized at 0.6℃. The second passivation treatment reached equilibrium, thus preparing a passivated nickel-based hydrogenation catalyst.

[0142] Catalytic hydrogenation method for toluene: A passivated nickel-based hydrogenation catalyst is used in a hydrogen gas environment with a purity ≥ 99.99% and a hydrogen space velocity of 100 h⁻¹. -1 The toluene was activated at 250℃ for 1 hour, followed by catalytic hydrogenation of toluene to prepare methylcyclohexane. The process parameters for the hydrogenation reaction included a toluene feed space velocity of 5 h⁻¹. -1 The reaction temperature is 150℃ and the reaction pressure is 3MPa.

[0143] After the reaction was completed, the conversion rate of toluene was 84.3%, and the selectivity of the target product was 99.5%.

[0144] As can be seen from Comparative Example 3, when the first passivation gas is replaced with CO2, some Ni will react with it to form nickel-like carbonates. These substances will still be protected by oxygen in the subsequent oxygen passivation. However, due to the high difficulty in re-reducing the products, the activity is significantly reduced under the conditions of this patent.

[0145] Comparative Example 4

[0146] The passivation method for nickel-based hydrogenation catalysts is basically the same as in Example 1, with the main difference being that the initial space velocity of the first gas is 50 h⁻¹. -1 .

[0147] Catalytic hydrogenation of benzene: Same as in Example 1. After the reaction, the conversion rate of toluene was 75.6%, and the selectivity of the target product was 99.2%.

[0148] Comparative Example 5

[0149] The passivation method for nickel-based hydrogenation catalysts is basically the same as in Example 1, with the main difference being that the first gas space velocity is 150 h⁻¹. -1 .

[0150] Catalytic hydrogenation of benzene: Same as in Example 1. After the reaction, the conversion rate of toluene was 56.2%, and the selectivity of the target product was 99.2%.

[0151] Comparative Examples 4 and 5 confirmed that both slightly lower and slightly higher reaction space velocities of the first gas affect the conversion rate of toluene.

[0152] The scanning electron microscope image of the passivated nickel-based hydrogenation catalyst prepared in Example 1 of this application is shown below. Figure 1 As shown. By Figure 1 It is evident that the surface material of the passivated nickel-based hydrogenation catalyst is uniformly distributed after passivation, and a dense and uniform oxide layer is formed on the catalyst surface.

[0153] TPR analysis was performed on the passivated nickel-based hydrogenation catalysts from Example 1 and Comparative Example 1, as well as the newly prepared reduced non-passivated nickel-based hydrogenation catalyst, to obtain hydrogen absorption spectra. The corresponding hydrogen absorption spectra are shown below. Figure 2 As shown. By Figure 2 As can be seen, the passivated nickel-based hydrogenation catalyst of Comparative Example 1 exhibits a significantly reduced hydrogen absorption peak at high temperatures, indicating that approximately 25% of the active sites require even higher temperatures to begin reduction. In contrast, the passivated nickel-based hydrogenation catalyst obtained by the passivation method in Example 1 of this application shows a reduction peak concentrated in the low-temperature region, with no absorption peak in the high-temperature region, indicating that almost no active sites are lost.

[0154] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0155] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A passivation method for a nickel-based hydrogenation catalyst, characterized in that, Includes the following steps: A pre-reduced nickel-based hydrogenation catalyst was prepared by reducing the nickel-based hydrogenation catalyst with hydrogen gas. The pre-reduced nickel-based hydrogenation catalyst is subjected to a first passivation treatment using a first gas to form a precursor layer on its surface, thereby preparing an intermediate. The first gas comprises water vapor and has a gas space velocity of 80 h⁻¹. -1 ~120h -1 ; The intermediate is subjected to a second passivation treatment using a second gas, which transforms the precursor layer into a nickel oxide protective layer, thereby preparing a passivated nickel-based hydrogenation catalyst; the second gas includes oxygen.

2. The passivation method for the nickel-based hydrogenation catalyst according to claim 1, characterized in that, The preparation steps of the pre-reduced nickel-based hydrogenation catalyst include: With hydrogen purity ≥90% and hydrogen space velocity 50h⁻¹ -1 ~100h -1 The nickel-based hydrogenation catalyst was reduced at a temperature of 450℃~550℃, and the water vapor concentration in the reaction tail gas was detected to be ≤100ppm, thus preparing the pre-reduced nickel-based hydrogenation catalyst.

3. The passivation method for the nickel-based hydrogenation catalyst according to claim 1 or 2, characterized in that, The first gas comprises, by volume fraction, 99% to 99.9% of a first inert gas and 0.1% to 1% of the water vapor.

4. The passivation method for the nickel-based hydrogenation catalyst according to claim 3, characterized in that, The step of performing a first passivation treatment on the pre-reduced nickel-based hydrogenation catalyst using a first gas includes: The pre-reduced nickel-based hydrogenation catalyst was cooled to 60°C to 120°C at a cooling rate of 5°C / min to 10°C / min, with the first gas space velocity at 80 h⁻¹. -1 ~120h -1 The pre-reduced nickel-based hydrogenation catalyst is subjected to a first passivation treatment of 0.8h~1.2h under the condition of temperature rise ≤3℃. After the equilibrium of the first passivation treatment is detected, the intermediate is prepared. The step of detecting the equilibrium of the first passivation treatment includes: increasing the flow rate of the first gas by 5 mL / min to 15 mL / min, performing the first passivation treatment for 25 min to 35 min each time, and when the temperature rise of the catalyst is ≤1℃, the first passivation treatment is considered to be in equilibrium.

5. The passivation method for the nickel-based hydrogenation catalyst according to claim 1 or 2, characterized in that, The second gas comprises, by volume fraction, 99% to 99.9% of a second inert gas and 0.1% to 1% of the oxygen.

6. The passivation method for the nickel-based hydrogenation catalyst according to claim 5, characterized in that, The step of performing a second passivation treatment on the intermediate using a second gas includes: The intermediate is heated to 120°C to 150°C at a heating rate of 2°C / min to 5°C / min, while the second gas space velocity is 80 h⁻¹. -1 ~120h -1 The intermediate is subjected to a second passivation treatment for 0.8h to 1.2h under the condition that the temperature rise is ≤3℃. After the equilibrium of the second passivation treatment is detected, the passivated nickel-based hydrogenation catalyst is prepared. The step of detecting the equilibrium of the second passivation treatment includes: increasing the flow rate of the second gas by 5 mL / min to 15 mL / min, performing the second passivation treatment for 25 min to 35 min each time, and when the temperature rise of the catalyst is ≤1℃, the second passivation treatment is considered to be in equilibrium.

7. The passivation method for the nickel-based hydrogenation catalyst according to claim 1 or 2, characterized in that, The nickel-based hydrogenation catalyst has one or more of the following characteristics: (1) The particle size of the nickel-based hydrogenation catalyst is 2 mm to 3 mm; (2) The nickel-based hydrogenation catalyst includes a support and an active component supported on the support, wherein the active component includes nickel; wherein the mass fraction of nickel in the nickel-based hydrogenation catalyst is 8% to 15%.

8. A passivated nickel-based hydrogenation catalyst, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 7.

9. A catalytic hydrogenation method, characterized in that, The process includes the following steps: after activating the passivated nickel-based hydrogenation catalyst as described in claim 8, the catalytic reactants undergo a hydrogenation reaction; The activation process parameters for the passivated nickel-based hydrogenation catalyst include: hydrogen purity ≥ 90% and hydrogen space velocity of 90 h⁻¹. -1 ~110h -1 The activation temperature is 200℃~260℃.

10. The catalytic hydrogenation method according to claim 9, characterized in that, The process parameters for catalytic hydrogenation of the reactants include: a feed space velocity of 1 h⁻¹ for the reactants. -1 ~6h -1 The reaction temperature is 120℃~180℃ and the reaction pressure is 2MPa~4MPa.

Images