Benzene partial hydrogenation catalyst as well as preparation method and application thereof

Abstract

The invention provides a preparation method of a benzene partial hydrogenation catalyst, which comprises the following steps: preparing an acidic solution from a metal ruthenium salt and a metal zinc salt, preparing an alkaline solution from sodium hydroxide and an organic amine substance, dropwise adding the alkaline solution into the acidic solution, and aging while keeping stirring to form a catalyst precursor slurry; and reducing and modifying to obtain the partial hydrogenation catalyst for benzene. In the modification step, on one hand, organic amine adsorbed on the catalyst is removed by utilizing the acidic property of the zinc sulfate solution, and on the other hand, in the process of removing the organic amine, zinc sulfate is in a weakly alkaline environment, and under the condition, basic zinc sulfate composite salt can be formed and is left on the surface of the catalyst, so that the surface of the catalyst is protected. Therefore, organic amine is replaced to become a dispersing agent of ruthenium nanoparticles, the nanometer form of the catalyst is maintained, the hydrophilicity of the surface of the catalyst is improved, and the selectivity of the catalyst is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of noble metal hydrogenation catalysis, and particularly relates to a benzene partial hydrogenation catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] The cyclohexene hydration process for cyclohexanone is the mainstream process in China at present. Compared with the traditional cyclohexane oxidation process, it has the characteristics of high atom utilization rate, hydrogen source saving, few side reactions, and environmental friendliness. In recent years, all new cyclohexanone projects in China have adopted cyclohexene hydration, and the most critical technology for this process is the benzene partial hydrogenation to cyclohexene technology. From a thermodynamic perspective, benzene hydrogenation is more inclined to produce cyclohexane. Multiple studies have shown that to improve the selectivity of cyclohexene, the catalyst needs to have appropriate hydrogenation activity, and at the same time, relying on the solubility difference between benzene and cyclohexene in the aqueous phase in the reaction system, the generated cyclohexene is separated from the catalyst in a timely manner to improve the selectivity of cyclohexene.

[0003] The idea of benzene partial hydrogenation to cyclohexene was first proposed in the 1930s. In 1989, Asahi Kasei Chemical Industry Co., Ltd. of Japan used a ruthenium-zinc catalyst to successfully conduct an industrial test of benzene partial hydrogenation to cyclohexene in Mizushima for the first time, and this technology was introduced into China in the 1990s. With the rapid development of the cyclohexene method cyclohexanone process in China in recent years, the benzene partial hydrogenation to cyclohexene technology, especially the research and development of the benzene partial hydrogenation catalyst used, has attracted the attention of many domestic enterprises and research institutions. In recent years, both the users and the manufacturers of the catalyst have been increasingly pursuing high activity and high yield of the catalyst.

[0004] Patent CN116764629A discloses a preparation method of a benzene partial hydrogenation to cyclohexene catalyst. The described catalyst uses reduced graphene oxide as a carrier, ruthenium as an active component, and zinc and aluminum as additives. Its graphene carrier can increase the specific surface area of the catalyst, thereby improving the catalytic activity of ruthenium, and at the same time can avoid the aggregation of ruthenium particles. The prepared catalyst can obtain a cyclohexene yield of 61.7%. However, using graphene as a carrier is not suitable for current industrial applications.

[0005] Patent CN114618488A discloses a preparation method of a hydrogenation to cyclohexene bimetallic alloy microcrystal catalyst. The described catalyst is a Ru-Zn alloy particle catalyst, and after being treated with a zinc sulfate solution, a water-retention film is formed to increase the specific surface area of the catalyst and obtain high catalytic activity and selectivity. Since the main components of this catalyst are Ru and Zn, which are similar to the process application conditions, and the activity index γ40 reaches more than 130, it is suitable for industrial applications. However, in the preparation process, a hydrogen partial pressure of 8-10 MPa and a temperature of 160-180 °C are required, and the preparation conditions are relatively harsh.

[0006] Patent CN106268794A: A preparation method of a catalyst for the partial hydrogenation of benzene to cyclohexene. The core of the catalyst preparation method is to modify the Ru-Zn nanoscale catalyst with Zn(OH)2 and oxygen. However, the conversion rate of the described catalyst is less than 50%, the selectivity is about 80%, and the yield is less than 40%, resulting in relatively low catalyst performance.

[0007] The cyclohexene hydration cyclohexanone process has been very mature in China. Major manufacturers are pursuing high-performance catalysts for the partial hydrogenation of benzene applicable to the current ruthenium-zinc-zirconium oxide-zinc sulfate system. Therefore, as described in patent CN116764629A, catalysts with other carriers or other elements will be limited in current process applications. For high-performance catalysts, a smaller catalyst particle size is required to increase the active centers of the catalyst. On the other hand, the hydrophilicity of the catalyst surface needs to be ensured to improve the selectivity of cyclohexene. At the same time, nanoscale catalyst particles are prone to agglomeration. After agglomeration, the ions not only reduce the catalyst activity but also are easily separated from zirconium oxide, causing loss. The water-retention film mentioned in patent CN114618488A plays a crucial role, but the described catalyst preparation conditions are too harsh. Summary of the Invention

[0008] In view of this, the present invention aims to provide a catalyst for the partial hydrogenation of benzene, its preparation method and application, to solve the problems of harsh catalyst preparation conditions, easy agglomeration of nanoscale catalyst particles, and relatively low catalyst performance in the prior art.

[0009] To achieve the above object, the technical solution of the present invention is realized as follows: The first aspect of the present invention provides a preparation method of a catalyst for the partial hydrogenation of benzene, comprising the following steps: S1: Preparation of the catalyst precursor: Prepare an acidic solution from a metal ruthenium salt and a metal zinc salt, and prepare a basic solution from sodium hydroxide and an organic amine substance. At a certain temperature, drop the basic solution into the acidic solution and age while maintaining stirring to form a catalyst precursor slurry; S2: Reduction: Transfer the catalyst precursor slurry obtained in S1 to a reaction kettle. After purging with an inert gas, fill it with hydrogen and carry out a reduction reaction. After waiting for the reaction kettle to cool down, drain the catalyst slurry, and wash the catalyst slurry with demineralized water until the pH of the catalyst slurry reaches 8-9 to obtain a reduced catalyst slurry; S3: Modification: Transfer the reduced catalyst slurry to a reaction kettle, add a zinc sulfate solution to prepare a slurry, purge with an inert gas, fill it with hydrogen, and react at a certain temperature. After the reaction ends, cool down, discharge the material, and wash until the pH is 6-7 to obtain the finished catalyst.

[0010] Further, the ruthenium metal salt in S1 is a water-soluble inorganic ruthenium metal salt compound, and the zinc metal salt is a water-soluble zinc metal compound.

[0011] Furthermore, the ruthenium metal salt in S1 is at least one of ruthenium trichloride, ruthenium sulfate, and ruthenium nitrate, preferably ruthenium trichloride; The zinc metal salt is at least one of zinc chloride, zinc sulfate, and zinc nitrate, preferably zinc chloride.

[0012] Further, the mass ratio of the ruthenium metal salt to the zinc metal salt in S1 is 1:(0.01 - 0.5), preferably 1:(0.02 - 0.2); The mass concentration of the ruthenium metal salt and zinc metal salt aqueous solution in S1 is 5 - 15%, and the mass concentration is preferably 5 - 10%.

[0013] Further, the aging time in S1 is 0.5 - 1 h; Preferably, the reduction reaction temperature in S2 is 120 - 150 °C, and the reduction reaction time is 4 - 15 h.

[0014] Further, the mass concentration of sodium hydroxide in the alkaline solution in S1 is 5 - 15%, and the mass concentration is preferably 5 - 10%; The molar ratio of the organic amine substance to the ruthenium metal salt is (0.01 - 0.2):1, preferably (0.05 - 0.1):1; The mass ratio of the acidic solution to the alkaline solution is 1:(0.2 - 1), preferably 1:(0.3 - 0.8).

[0015] Further, the organic amine substances in S1 include at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide, preferably tetraethylammonium hydroxide or tetrapropylammonium hydroxide.

[0016] Further, the temperature in S1 is 70 - 80 °C.

[0017] Further, the inert gas in S2 is nitrogen.

[0018] Further, the inert gas in S3 is nitrogen.

[0019] Further, the mass concentration of zinc sulfate in the zinc sulfate solution in S3 is 0.1 - 5%, preferably 0.5 - 3%; The mass ratio of the catalyst to zinc sulfate is 1:(0.1 - 2), preferably 1:(0.5 - 1.5).

[0020] Further, in S3, the hydrogen partial pressure is 0.1 - 2 MPa, preferably 0.5 - 1.5 MPa; the reaction temperature is 80 - 120 °C, preferably 90 - 110 °C; and the reaction time is 1 - 5 h, preferably 2 - 4 h.

[0021] In the present invention, by utilizing the adsorption effect of ruthenium on the lone pair electrons of organic nitrogen, during the precipitation process of metal ruthenium salt and metal zinc salt, basic organic amine substances such as TMAOH, TEAOH, TPAOH, or TBAOH are introduced. When ruthenium adsorbs organic amine, the adsorption effect between ruthenium atoms is weakened, and the agglomeration effect between ruthenium particles is reduced, thereby forming a nanoscale catalyst precursor.

[0022] The above catalyst precursor is subjected to a reduction operation under a hydrogen atmosphere. Due to the adsorption effect of the lone pair electrons of Ru - N, after the reduction of the catalyst precursor is completed, the dispersed state of the catalyst particles can still be maintained.

[0023] After the above catalyst is washed with water to remove chloride ions, a weakly acidic zinc sulfate solution is added, and modification treatment is carried out at a certain temperature. Since organic amine substances are alkaline, they are more likely to dissolve in the acidic zinc sulfate solution, thereby removing the organic amine substances on the catalyst surface. Organic amine substances are equivalent to toxic substances for precious metals. If this operation is not carried out, the activity of the catalyst will be affected. This step is equivalent to the ion exchange between zinc sulfate and organic amine. Although organic amine substances have certain alkalinity, during the exchange process, an insoluble basic zinc sulfate composite salt will be formed on the surface of ruthenium atoms, similar to the anchoring of zinc sulfate by organic amine substances on the catalyst, improving the hydrophilicity of the catalyst, which is very helpful for the selectivity of cyclohexene.

[0024] After the modification with zinc sulfate, the dispersant of the catalyst is replaced by basic zinc sulfate salt, which is beneficial to the partial hydrogenation reaction. And the catalyst always maintains the dispersed form of ruthenium particles, preventing agglomeration.

[0025] The above catalyst is washed to remove the amine substances in the solution, thereby obtaining a highly dispersed benzene partial hydrogenation catalyst.

[0026] The second aspect of the present invention provides a benzene partial hydrogenation catalyst prepared by the preparation method of the benzene partial hydrogenation catalyst according to the first aspect of the present invention.

[0027] The third aspect of the present invention provides the application of the benzene partial hydrogenation catalyst described in the second aspect of the present invention in the partial hydrogenation of benzene to cyclohexene.

[0028] Compared with the prior art, the benzene partial hydrogenation catalyst, its preparation method and application described in the present invention have the following advantages: (1) In the present invention, an organic amine substance is introduced into the ruthenium-zinc coprecipitation compound. By utilizing the adsorption of ruthenium on the organic amine, the agglomeration between ruthenium particles is reduced, thereby improving the dispersibility of the catalyst. (2) In the process of forming elemental ruthenium from ruthenium hydroxide in the present invention, the adsorption state of the organic amine substance on the ruthenium catalyst is maintained. Through washing, only the excess other metal ions are removed. (3) On the one hand, in the present invention, the acidic property of the zinc sulfate solution is utilized to remove the organic amine adsorbed on the catalyst. On the other hand, during the process of removing the organic amine, zinc sulfate is in a weakly alkaline environment. Under this condition, basic zinc sulfate composite salt will be formed and remain on the catalyst surface. Thus, not only does it replace the organic amine as the dispersant of ruthenium nanoparticles, maintaining the nano-morphology of the catalyst, but also it improves the hydrophilicity of the catalyst surface and enhances the selectivity of the catalyst. (4) When the benzene conversion rate of the benzene partial hydrogenation catalyst described in the present invention is 60%, the cyclohexene selectivity can reach about 85%, and the activity index γ40 is between 140 and 150. It has the characteristics of high selectivity and low unit consumption in industrial applications. In the case of the industrial benzene selective hydrogenation to cyclohexene device, the conversion rate exceeds 45%, the selectivity can reach 85%, and the unit consumption of the catalyst during continuous operation can be 1.2 g / t cyclohexanol. Description of the Drawings

[0029] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 is the electron microscope photograph of the catalyst prepared in Example 1 of the present invention; Figure 2 is the electron microscope photograph of the catalyst prepared in Example 2 of the present invention; Figure 3 is the electron microscope photograph of the catalyst prepared in Example 3 of the present invention; Figure 4 is the electron microscope photograph of the catalyst prepared in Example 4 of the present invention; Figure 5 is the electron microscope photograph of the catalyst prepared in Example 5 of the present invention; Figure 6 is the electron microscope photograph of the catalyst prepared in Example 6 of the present invention; Figure 7 is the electron microscope photograph of the catalyst prepared in Example 7 of the present invention; Figure 8 is the electron microscope photograph of the catalyst prepared in Comparative Example 1 of the present invention; Figure 9 is the electron microscope photograph of the catalyst prepared in Comparative Example 2 of the present invention; Figure 10 The electron microscope photograph of the catalyst prepared in Comparative Example 3 of the present invention; Detailed implementation mode

[0030] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0031] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0032] Example 1 A preparation method of a partial hydrogenation catalyst for benzene, comprising the following steps: S1: Preparation of catalyst precursor Take 30 g of ruthenium trichloride and 1.5 g of zinc chloride respectively, add water to 400 g, stir and prepare an acidic solution at 70 °C. Separately prepare 200 g of a sodium hydroxide solution with a concentration of 10%, add 0.6 g of tetrapropylammonium hydroxide, stir evenly, and prepare a basic solution. Slowly drip the prepared basic solution into the acidic solution, and stir at 70 °C for 1 h to form a catalyst precursor slurry.

[0033] S2: Reduction of catalyst precursor Transfer the above catalyst precursor slurry to a Hastelloy reactor. After replacing the air with nitrogen, charge 4 MPa of hydrogen, start stirring, heat up to 140 °C, and react for 6 h. After waiting for the reactor to cool down, discharge the catalyst slurry, and wash the catalyst slurry with demineralized water until the pH of the catalyst slurry reaches 8 - 9 to obtain a reduced catalyst slurry.

[0034] S3: Catalyst modification Transfer the above reduced catalyst slurry to a Hastelloy reactor. Separately take 10 g of zinc sulfate, prepare it into a 1% solution, add it to the Hastelloy reactor. After replacing the air with nitrogen, charge 1 MPa of hydrogen, slowly heat up to 100 °C, and react for 2 h. After waiting for the reactor to cool down, discharge the catalyst slurry, and wash the catalyst slurry with demineralized water until the pH of the slurry is 6 - 7 to obtain the finished catalyst.

[0035] Example 2 A preparation method of a partial hydrogenation catalyst for benzene, comprising the following steps: S1: Preparation of catalyst precursor Take 30 g of ruthenium trichloride and 2 g of zinc sulfate respectively, add water to 300 g, stir and prepare an acidic solution at 80 °C. Separately prepare 150 g of a sodium hydroxide solution with a concentration of 10%, add 0.6 g of tetraethylammonium hydroxide, stir evenly, and prepare a basic solution. Slowly drip the prepared basic solution into the acidic solution, and stir at 80 °C for 1 h to form a catalyst precursor slurry.

[0036] S2: Reduction of catalyst precursor Transfer the above-mentioned catalyst precursor slurry into a Hastelloy reactor. After displacing air with nitrogen, charge 4 MPa of hydrogen, start stirring, heat up to 140 °C, and react for 8 h. After waiting for the reactor to cool down, discharge the catalyst slurry, and wash the catalyst slurry with demineralized water until the pH of the catalyst slurry reaches 8 - 9 to obtain a reduced catalyst slurry.

[0037] S3: Catalyst modification Transfer the above-mentioned reduced catalyst slurry into a Hastelloy reactor. Take another 15 g of zinc sulfate and prepare it into a 1% solution, then add it to the Hastelloy reactor. After displacing air with nitrogen, charge 1 MPa of hydrogen, slowly heat up to 90 °C, and react for 2 h. After waiting for the reactor to cool down, discharge the catalyst slurry, and wash the catalyst slurry with demineralized water until the pH of the slurry is 6 - 7 to obtain the finished catalyst.

[0038] Example 3 A preparation method of a partial hydrogenation catalyst for benzene, comprising the following steps: S1: Preparation of catalyst precursor Take 30 g of ruthenium trichloride and 2 g of zinc sulfate respectively, add water to 300 g, and stir at 80 °C to prepare an acidic solution. Prepare another 150 g of a 15% sodium hydroxide solution, add 0.6 g of tetraethylammonium hydroxide, stir evenly to prepare a basic solution, slowly drip the prepared basic solution into the acidic solution, and stir at 80 °C for 1 h to form a catalyst precursor slurry.

[0039] S2: Reduction of catalyst precursor Transfer the above-mentioned catalyst precursor slurry into a Hastelloy reactor. After displacing air with nitrogen, charge 4 MPa of hydrogen, start stirring, heat up to 140 °C, and react for 8 h. After waiting for the reactor to cool down, discharge the catalyst slurry, and wash the catalyst slurry with demineralized water until the pH of the catalyst slurry reaches 8 - 9 to obtain a reduced catalyst slurry.

[0040] S3: Catalyst modification Transfer the above-mentioned reduced catalyst slurry into a Hastelloy reactor. Take another 15 g of zinc sulfate and prepare it into a 1% solution, then add it to the Hastelloy reactor. After displacing air with nitrogen, charge 1 MPa of hydrogen, slowly heat up to 90 °C, and react for 2 h. After waiting for the reactor to cool down, discharge the catalyst slurry, and wash the catalyst slurry with demineralized water until the pH of the slurry is 6 - 7 to obtain the finished catalyst.

[0041] Example 4 A preparation method of a partial hydrogenation catalyst for benzene, comprising the following steps: S1: Preparation of catalyst precursor Weigh 30 g of ruthenium trichloride and 2 g of zinc chloride separately, add water to make up to 350 g, and stir at 80 °C to prepare an acidic solution. Separately prepare 130 g of a 10% sodium hydroxide solution, add 0.6 g of tetrabutylammonium hydroxide, stir evenly to prepare a basic solution. Slowly add the prepared basic solution dropwise to the acidic solution, and stir at 80 °C for 1 h to form a catalyst precursor slurry.

[0042] S2: Reduction of the catalyst precursor Transfer the above catalyst precursor slurry to a Hastelloy reactor. After purging the air with nitrogen, charge 4 MPa of hydrogen, start stirring, heat up to 145 °C, and react for 6 h. After waiting for the reactor to cool down, drain the catalyst slurry, wash the catalyst slurry with demineralized water until the pH of the catalyst slurry reaches 8 - 9 to obtain a reduced catalyst slurry.

[0043] S3: Catalyst modification Transfer the above reduced catalyst slurry to a Hastelloy reactor. Weigh another 15 g of zinc sulfate, prepare it into a 2% solution, add it to the Hastelloy reactor. After purging the air with nitrogen, charge 1 MPa of hydrogen, slowly heat up to 90 °C, and react for 2 h. After waiting for the reactor to cool down, drain the catalyst slurry, wash the catalyst slurry with demineralized water until the pH of the slurry is 6 - 7 to obtain the finished catalyst.

[0044] Example 5 A preparation method of a benzene partial hydrogenation catalyst, comprising the following steps: S1: Preparation of the catalyst precursor Weigh 30 g of ruthenium trichloride and 1.8 g of zinc chloride separately, add water to make up to 300 g, and stir at 80 °C to prepare an acidic solution. Separately prepare 140 g of a 15% sodium hydroxide solution, add 1.2 g of tetrabutylammonium hydroxide, stir evenly to prepare a basic solution. Slowly add the prepared basic solution dropwise to the acidic solution, and stir at 80 °C for 1 h to form a catalyst precursor slurry.

[0045] S2: Reduction of the catalyst precursor Transfer the above catalyst precursor slurry to a Hastelloy reactor. After purging the air with nitrogen, charge 4 MPa of hydrogen, start stirring, heat up to 140 °C, and react for 6 h. After waiting for the reactor to cool down, drain the catalyst slurry, wash the catalyst slurry with demineralized water until the pH of the catalyst slurry reaches 8 - 9 to obtain a reduced catalyst slurry.

[0046] S3: Catalyst modification Transfer the above-reduced catalyst slurry to a Hastelloy reactor. Separately, take 12 g of zinc sulfate and prepare a 1.3% solution, which is then added to the Hastelloy reactor. After displacing the air with nitrogen, charge 1 MPa of hydrogen, slowly heat up to 100 °C, and react for 2 h. After waiting for the reactor to cool down, discharge the catalyst slurry, and wash the catalyst slurry with demineralized water until the pH of the slurry is 6 - 7 to obtain the finished catalyst.

[0047] Example 6 A preparation method of a partial hydrogenation catalyst for benzene, comprising the following steps: S1: Preparation of the catalyst precursor Take 30 g of ruthenium trichloride and 2 g of zinc nitrate respectively, add water to 320 g, and stir at 60 °C to prepare an acidic solution. Separately, prepare 200 g of a 5% sodium hydroxide solution, add 0.6 g of tetrapropylammonium hydroxide, stir evenly to prepare a basic solution, slowly drip the prepared basic solution into the acidic solution, and stir at 80 °C for 1 h to form a catalyst precursor slurry.

[0048] S2: Reduction of the catalyst precursor Transfer the above catalyst precursor slurry to a Hastelloy reactor. After displacing the air with nitrogen, charge 4 MPa of hydrogen, start stirring, heat up to 150 °C, and react for 8 h. After waiting for the reactor to cool down, discharge the catalyst slurry, and wash the catalyst slurry with demineralized water until the pH of the catalyst slurry reaches 8 - 9 to obtain the reduced catalyst slurry.

[0049] S3: Catalyst modification Transfer the above-reduced catalyst slurry to a Hastelloy reactor. Separately, take 13 g of zinc sulfate and prepare a 1% solution, which is then added to the Hastelloy reactor. After displacing the air with nitrogen, charge 1 MPa of hydrogen, slowly heat up to 90 °C, and react for 2 h. After waiting for the reactor to cool down, discharge the catalyst slurry, and wash the catalyst slurry with demineralized water until the pH of the slurry is 6 - 7 to obtain the finished catalyst.

[0050] Example 7 A preparation method of a partial hydrogenation catalyst for benzene, comprising the following steps: S1: Preparation of the catalyst precursor Take 30 g of ruthenium trichloride and 2.4 g of zinc chloride respectively, add water to 420 g, and stir at 60 °C to prepare an acidic solution. Separately, prepare 250 g of a 5% sodium hydroxide solution, add 0.6 g of tetrapropylammonium hydroxide, stir evenly to prepare a basic solution, slowly drip the prepared basic solution into the acidic solution, and stir at 80 °C for 1 h to form a catalyst precursor slurry.

[0051] S2: Reduction of the catalyst precursor Transfer the above catalyst precursor slurry into a Hastelloy reactor. After purging the air with nitrogen, charge 4 MPa of hydrogen, start stirring, heat up to 150 °C, and react for 8 h. After waiting for the reactor to cool down, discharge the catalyst slurry, and wash the catalyst slurry with demineralized water until the pH of the catalyst slurry reaches 8 - 9 to obtain the reduced catalyst slurry.

[0052] S3: Catalyst modification Transfer the above reduced catalyst slurry into a Hastelloy reactor. Take another 10 g of zinc sulfate and prepare it into a 0.6% solution, add it to the Hastelloy reactor. After purging the air with nitrogen, charge 1 MPa of hydrogen, slowly heat up to 100 °C, and react for 4 h. After waiting for the reactor to cool down, discharge the catalyst slurry, and wash the catalyst slurry with demineralized water until the pH of the slurry is 6 - 7 to obtain the finished catalyst.

[0053] Comparative Example 1 A preparation method of a benzene partial hydrogenation catalyst includes the following steps: S1: Preparation of catalyst precursor Take 30 g of ruthenium trichloride and 2.4 g of zinc chloride respectively, add water to 420 g, and stir at 60 °C to prepare an acidic solution. Prepare another 250 g of a 5% sodium hydroxide solution to form an alkaline solution. Slowly drip the prepared alkaline solution into the acidic solution and stir at 80 °C for 1 h to form a catalyst precursor slurry.

[0054] S2: Reduction of catalyst precursor Transfer the above catalyst precursor slurry into a Hastelloy reactor. After purging the air with nitrogen, charge 4 MPa of hydrogen, start stirring, heat up to 150 °C, and react for 8 h. After waiting for the reactor to cool down, discharge the catalyst slurry, and wash the catalyst slurry with demineralized water until the pH of the catalyst slurry reaches 8 - 9 to obtain the reduced catalyst slurry.

[0055] S3: Catalyst modification Transfer the above reduced catalyst slurry into a Hastelloy reactor. Take another 10 g of zinc sulfate and prepare it into a 0.6% solution, add it to the Hastelloy reactor. After purging the air with nitrogen, charge 1 MPa of hydrogen, slowly heat up to 100 °C, and react for 4 h. After waiting for the reactor to cool down, discharge the catalyst slurry, and wash the catalyst slurry with demineralized water until the pH of the slurry is 6 - 7 to obtain the finished catalyst.

[0056] Comparative Example 2 A preparation method of a benzene partial hydrogenation catalyst includes the following steps: S1: Preparation of catalyst precursor Weigh 30 g of ruthenium trichloride and 2.4 g of zinc chloride respectively, add water to make up to 420 g, and stir at 60 °C to prepare an acidic solution. Separately, prepare 250 g of a sodium hydroxide solution with a concentration of 5%, add 0.6 g of tetrapropylammonium hydroxide, stir evenly to prepare an alkaline solution. Slowly add the prepared alkaline solution dropwise to the acidic solution, and stir at 80 °C for 1 h to form a catalyst precursor slurry.

[0057] S2: Reduction of the catalyst precursor Transfer the above catalyst precursor slurry to a Hastelloy reactor. After purging the air with nitrogen, charge 4 MPa of hydrogen, start stirring, heat up to 150 °C, and react for 8 h. After waiting for the reactor to cool down, drain the catalyst slurry, and wash the catalyst slurry with demineralized water until the pH of the catalyst slurry reaches 8 - 9 to obtain the finished catalyst.

[0058] Comparative Example 3 A preparation method of a benzene partial hydrogenation catalyst comprises the following steps: S1: Preparation of the catalyst precursor Weigh 30 g of ruthenium trichloride and 2.4 g of zinc chloride respectively, add water to make up to 420 g, and stir at 60 °C to prepare an acidic solution. Separately, prepare 250 g of a sodium hydroxide solution with a concentration of 5% to prepare an alkaline solution. Slowly add the prepared alkaline solution dropwise to the acidic solution, and stir at 80 °C for 1 h to form a catalyst precursor slurry.

[0059] S2: Reduction of the catalyst precursor Transfer the above catalyst precursor slurry to a Hastelloy reactor. After purging the air with nitrogen, charge 4 MPa of hydrogen, start stirring, heat up to 150 °C, and react for 8 h. After waiting for the reactor to cool down, drain the catalyst slurry, and wash the catalyst slurry with demineralized water until the pH of the catalyst slurry reaches 8 - 9 to obtain the finished catalyst.

[0060] In the above examples and comparative examples, the catalyst evaluation is carried out by the following method: Weigh the catalyst slurries prepared in the above examples and comparative examples, and obtain the dried filter cake by suction filtration with a funnel. Using the drying weight method, dry the sample in a vacuum drying oven at 80 °C to measure the solid content of the catalyst slurry.

[0061] Accurately weigh 2 g of the above-mentioned dried filter cake on a dry basis, 10 g of zirconia, and 50 g of zinc sulfate heptahydrate, dissolve them in 100 ml of water, and add them to a 1 L high-pressure reactor. Then, rinse the container with 180 ml of water several times and pour it into the high-pressure reactor. Seal the reactor. After purging the air with nitrogen, fill it with hydrogen until the pressure reaches 4 MPa. Start stirring at a stirring speed of 800 - 850 rpm. Heat up to 140 ± 1 °C. Under normal circumstances, the pressure reaches 5 MPa at this time. After maintaining a constant temperature for 22 h, add 140 ml of pure benzene, continuously fill with hydrogen to maintain the pressure at 5 MPa, increase the stirring speed to 1400 rpm, start timing, and take samples every 5 min. Use a gas chromatograph equipped with an FID detector for detection, and use the corrected area normalization method to calculate the conversion rate and cyclohexene selectivity.

[0062] The evaluation results of the catalysts prepared in Examples 1 - 7 and Comparative Examples 1 - 3 are shown in Table 1.

[0063] Table 1 Evaluation results of catalyst samples in Examples 1 - 7 and Comparative Examples 1 - 3 Since the residence time in industrial plants is mostly 15 - 20 minutes, only the analysis results at 15 and 20 minutes are listed in Table 1. The units of conversion rate and selectivity in the table are both wt%.

[0064] As can be seen from Table 1, Examples 1 - 7 of the present invention can achieve high activity and high cyclohexene selectivity of the benzene selective hydrogenation catalyst. In industrial applications, due to the dispersibility of catalyst particles, characteristics such as good stability and low consumption can be exhibited.

[0065] Figure 1-10 These are the electron microscope photos of the catalysts in Examples 1 - 7 and Comparative Examples 1 - 3 of the present invention. Among them, Figure 1-6 This is a high-magnification TEM electron microscope photo, and the surface catalyst particle size is 4 - 6 nm. Figures 7-10 This is a TEM electron microscope photo with a smaller magnification, corresponding to Example 7 and Comparative Examples 1 - 3 respectively. Among them, in Comparative Examples 1 and 3, since no organic amine was added, the catalyst particle size is relatively large, about 8 - 10 nm, and the particles are uneven. In particular, Comparative Example 3 has obvious agglomeration phenomena. While in Comparative Example 2, organic amine was added, and the particle size is significantly smaller, but due to no zinc sulfate treatment, the organic amine on the surface seriously affects the catalyst activity.

[0066] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a benzene partial hydrogenation catalyst, characterized in that: The following steps are involved: S1: Preparation of catalyst precursor: preparing an acidic solution with metal ruthenium salt and metal zinc salt, preparing an alkaline solution with sodium hydroxide and an organic amine substance, adding the alkaline solution dropwise into the acidic solution at a certain temperature, and aging the solution under stirring to form a catalyst precursor slurry; S2: Reduction: The catalyst precursor slurry obtained in S1 is transferred to a reactor, and after inert gas replacement, hydrogen is introduced to perform a reduction reaction. After the reactor is cooled down, the catalyst slurry is discharged and washed with desalted water until the pH of the catalyst slurry reaches 8-9, thereby obtaining a reduced catalyst slurry; S3: Modification: Transfer the reduced catalyst slurry to the reactor, add zinc sulfate solution to prepare slurry, replace with inert gas, fill with hydrogen, react at a certain temperature, after the reaction is completed, cool down and wash the material to pH 6~7 to obtain the finished catalyst.

2. The method for preparing a benzene partial hydrogenation catalyst according to claim 1, wherein: The metal ruthenium salt in S1 is a water-soluble inorganic metal ruthenium salt compound, and the metal zinc salt is a water-soluble metal zinc compound.

3. The method for preparing a benzene partial hydrogenation catalyst according to claim 1, wherein: The metal ruthenium salt in S1 is at least one of ruthenium trichloride, ruthenium sulfate, and ruthenium nitrate, preferably ruthenium trichloride; The metal zinc salt is at least one of zinc chloride, zinc sulfate and zinc nitrate, preferably zinc chloride.

4. The method for preparing a benzene partial hydrogenation catalyst according to claim 1, wherein: The mass ratio of the metal ruthenium salt to the metal zinc salt in S1 is 1:(0.01-0.5), preferably 1:(0.02-0.2); The mass concentration of the aqueous solution of metal ruthenium salt and metal zinc salt in S1 is 5-15%, and the mass concentration is preferably 5-10%.

5. The method for preparing a benzene partial hydrogenation catalyst according to claim 1, characterized in that: The aging time in S1 is 0.5-1h; Preferably, the reduction reaction temperature in S2 is 120-150° C., and the reduction reaction time is 4-15 h.

6. The method for preparing a benzene partial hydrogenation catalyst according to claim 1, characterized in that: The mass concentration of sodium hydroxide in the alkaline solution in S1 is 5-15%, and the mass concentration is preferably 5-10%; The molar ratio of the organic amine substance to the metal ruthenium salt is (0.01-0.2):1, preferably (0.05-0.1):1; The mass ratio of the acidic solution to the alkaline solution is 1:(0.2-1), preferably 1:(0.3-0.8).

7. The method for preparing a benzene partial hydrogenation catalyst according to claim 1, characterized in that: The organic amine substance in S1 includes at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide, preferably tetraethylammonium hydroxide or tetrapropylammonium hydroxide.

8. The method for preparing a benzene partial hydrogenation catalyst according to claim 1, characterized in that: The mass concentration of zinc sulfate in the zinc sulfate solution in S3 is 0.1-5%, preferably 0.5-3%; The mass ratio of the catalyst to zinc sulfate is 1:(0.1-2), preferably 1:(0.5-1.5).

9. A benzene partial hydrogenation catalyst prepared according to the method for preparing a benzene partial hydrogenation catalyst according to any one of claims 1 to 8.

10. Use of the benzene partial hydrogenation catalyst according to claim 9 in preparing cyclohexene by partial hydrogenation of benzene.

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