A bimetallic Ru-Mo / gamma-Al2O3 catalyst, a preparation method and application thereof

Abstract

The present application relates to a kind of bimetallic Ru-Mo / γ-Al2O3 catalyst and its preparation method and application, belong to the technical field of chemical synthesis.The catalyst is with N-γ-Al2O3 as carrier, active component Ru and adjuvant Mo are loaded on N-γ-Al2O3 by impregnation method, Ru-Mo / N-γ-Al2O3 catalyst is prepared, after ammonia treatment γ-Al2O3 makes its surface from Lewis acid site become Lewis base site, metal nano ion has stronger anchoring effect, so as to help better dispersion of nano ion.The catalyst can be used to prepare cyclohexane diformic acid dialkyl ester from dialkyl phthalate, after reaction, the component of catalyst changes little, still maintain higher activity, can be recycled and reused, it is conducive to industrialized mass production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cyclohexane dicarboxylic acid dialkyl ester preparation, and in particular to a bimetallic Ru-Mo / gamma-Al2O3 catalyst, a preparation method and application thereof. BACKGROUND

[0002] Plasticizer is the largest variety of plastic processing aids in capacity and consumption, widely used in toys, building materials, automotive parts, electronics and medical components and a large number of durable and easy to shape plastic products, its output accounts for more than 60% of the total output of plastic additives. At present, there are more than 500 kinds of commercial plasticizers in the world, among which dialkyl phthalate plasticizers are the largest class of plasticizers in the market, accounting for more than 80% of the total output of the plasticizer market. Mainly including diisononyl phthalate, di(2-ethylhexyl) phthalate, diisooctyl phthalate and dibutyl phthalate. However, in recent years, studies have shown that phthalate plasticizers (PAEs) are prone to migration, causing pollution to food and biomedical materials, thereby posing certain harm to human health. At present, more and more countries limit or prohibit their use in medical devices, children's toys and food packaging fields.

[0003] At present, the main methods for synthesizing cyclohexane dicarboxylic acid dialkyl esters are direct hydrogenation method, direct esterification method and ester exchange method.

[0004] Cyclohexane dicarboxylic acid dialkyl ester is usually prepared by esterification of cyclohexane dicarboxylic anhydride with alkyl alcohol under the action of an acid catalyst. It is well known that esterification is a reversible reaction, and it is necessary to add excess alcohol and remove water generated by the reaction in time. Esterification requires high reaction temperature (250℃-260℃) and long reaction time, consumes a lot of energy, and has many by-products and catalyst deactivation.

[0005] The direct hydrogenation method is a method for preparing cyclohexane dicarboxylic acid dialkyl ester by directly hydrogenating dialkyl phthalate and hydrogen gas under the action of a catalyst. This method has the characteristics of low energy consumption, simple process, few by-products, green environmental protection and easy industrial production. Compared with direct esterification and ester exchange, direct hydrogenation is the mainstream method for developing new environmentally friendly plasticizers in the future.

[0006] The direct hydrogenation method usually uses noble metal catalysts (such as nickel, platinum, palladium, rhodium, ruthenium) to catalyze the catalytic hydrogenation reaction of dialkyl phthalate to obtain dialkyl cyclohexane dicarboxylate at high temperature and high pressure. Although this process route is simple, it has high requirements for equipment and catalysts and high cost. In the patent US6184917 of BASF Company in Germany, Ru supported catalyst is used to successfully prepare dialkyl cyclohexyl dicarboxylate under the condition of a pressure of 20 MPa, and industrial production is realized. In the US patent US7361714, a catalyst is used in the hydrogenation reaction under a pressure of 8-10 MPa, and the active component of the catalyst uses at least one Group VIII transition metal alone or at least one Group VI or Group VII transition metal. The patent CN107675109A discloses a preparation method of isooctyl cyclohexane dicarboxylate. Isooctyl phthalate and hydrogen are used as raw materials, Ru is used as a catalyst, and the catalytic hydrogenation reaction is carried out under the condition of a temperature of 160-200 ℃ and a pressure of 5-10 MPa to prepare diisooctyl cyclohexane dicarboxylate. The selectivity and purity of the product are both above 99%. In the above-mentioned patents, although the selectivity of the prepared dialkyl cyclohexane dicarboxylate is all above 99%, the pressure and temperature of the reaction are both high in the hydrogenation reaction process, the energy consumption is large, and it is not conducive to industrial production. The catalysts used are generally pure metals or metal supported catalysts. The metal active components are all above 3 wt%, and the cost is large. SUMMARY

[0007] The purpose of the present application is to overcome the shortcomings of the prior art and provide a bimetallic Ru-Mo / γ-Al2O3 catalyst, a preparation method and application thereof. The catalyst has mild reaction conditions, the content of the metal active component is less than 2 wt%, and the cost can be effectively reduced. The catalyst can effectively catalyze the preparation of dialkyl cyclohexane dicarboxylate. After the reaction is completed, the composition of the catalyst changes little, the activity is still high, the catalyst can be recycled and reused, and it is conducive to industrial large-scale production.

[0008] To achieve the above-mentioned purposes, the technical scheme adopted by the present application is as follows:

[0009] In a first aspect, the present application provides a preparation method of a bimetallic Ru-Mo / γ-Al2O3 catalyst, characterized in that the method comprises the following steps:

[0010] (1) mixing γ-Al2O3 with ammonia water, drying to obtain an N-γ-Al2O3 carrier;

[0011] (2) loading ruthenium salt and molybdenum salt on the N-γ-Al2O3 carrier, washing, then calcining, and then reducing to obtain the bimetallic Ru-Mo / γ-Al2O3 catalyst; wherein the mass content of ruthenium in the catalyst is 0.1-2 wt%, and the mass content of molybdenum is 0.1-2 wt%.

[0012] The catalyst of the present application is prepared by loading active components Ru and Mo on N-γ-Al2O3 carrier through impregnation, and the Ru-Mo / N-γ-Al2O3 catalyst is prepared. The γ-Al2O3 is treated by ammonia water to change the surface Lewis acid sites into Lewis base sites, which has stronger anchoring effect on metal nano ions, thus helping better dispersion of nano ions.

[0013] Specifically, the γ-Al2O3 has large specific surface area, high porosity, strong heat resistance, good formability and certain surface basicity. The reason for alkalinizing the γ-Al2O3 by ammonia water is that the pyrrole structure is formed in the γ-Al2O3 after the ammonia water treatment in the subsequent calcination process, so that the nitrogen atom is better anchored on the carrier, thus improving the selectivity of cyclohexane dimethyl dicarboxylate. The commonly used inorganic bases have no such effect.

[0014] Preferably, in the step (1), the concentration of the ammonia water is 5-15 mol / L; the mass ratio of γ-Al2O3 to ammonia water is 1:(5-10).

[0015] Preferably, in the step (1), the temperature of the mixing is 55-65℃, and the time is 5-7h; the temperature of the drying is 110-125℃.

[0016] Preferably, the ruthenium salt solution is one of RuCl3 solution and Ru(NO3)3 solution; and the molybdenum salt solution is one of Mo(NO3)2 solution and MoCl2 solution.

[0017] Preferably, the loading treatment is that the ruthenium salt solution and the molybdenum salt solution are sprayed on the surface of the N-γ-Al2O3 carrier, then standing for 7-9h, and then drying at 100-120℃.

[0018] Preferably, the temperature of the calcination is 400-600℃, and the time of the calcination is 2-5h; the temperature of the reduction reaction is 200-300℃, and the time of the reduction reaction is 3-5h.

[0019] Preferably, x is 0.1-1.5wt%, and y is 0.1-1.5wt%.

[0020] In the second aspect, the present application provides a bimetallic Ru-Mo / γ-Al2O3 catalyst prepared by the preparation method of the bimetallic Ru-Mo / γ-Al2O3 catalyst.

[0021] In the third aspect, the present application provides the application of the bimetallic Ru-Mo / γ-Al2O3 catalyst in preparing cyclohexane dimethyl dicarboxylate.

[0022] Preferably, the method for preparing cyclohexane dicarboxylic acid dialkyl ester comprises the following steps:

[0023] The catalytic hydrogenation reaction is carried out under the action of the bimetallic Ru-Mo / γ-Al2O3 catalyst with the raw material of the dialkyl phthalate and hydrogen, so that the dialkyl cyclohexane dicarboxylic acid ester is obtained.

[0024] The catalyst utilizes the modification of Mo on the Ru / N-γ-Al2O3 catalyst, and in the H2 atmosphere in the application of the product in the catalytic reaction process, there is a hydrogen overflow effect between the Ru-Mo metal particles, so that the H2 is more easily activated. The introduction of Mo not only greatly improves the activity of the catalyst, but also reduces the amount of the active component Ru. After the reaction is completed, the composition of the catalyst changes little, and the catalyst still maintains high activity, can be recycled and reused, and is conducive to industrialized mass production.

[0025] Preferably, the reaction temperature of the catalytic hydrogenation is 130-150°C, and the reaction pressure is 3.0-5.0 MPa; more preferably, the reaction temperature of the catalytic hydrogenation is 140°C, and the reaction pressure is 4 MPa. The liquid space velocity of the dialkyl phthalate is 0.1-2 h -1 .

[0026] Preferably, the dialkyl phthalate is at least one of diisononyl phthalate, di(2-ethylhexyl) phthalate, diisooctyl phthalate and dibutyl phthalate.

[0027] Preferably, the molar ratio of hydrogen to the dialkyl phthalate is (5-10):1. More preferably, the molar ratio of hydrogen to the dialkyl phthalate is (5-8):1.

[0028] Preferably, the addition amount of the bimetallic Ru-Mo / γ-Al2O3 catalyst is 2%-8% of the mass of the raw material.

[0029] Compared with the prior art, the application has the following beneficial effects:

[0030] (1) The preparation method of the catalyst of the application is to load the active component Ru and the auxiliary agent Mo on the N-γ-Al2O3 by impregnation, to prepare the Ru-Mo / N-γ-Al2O3 catalyst, and to treat the γ-Al2O3 with ammonia to change the surface of the γ-Al2O3 from Lewis acid sites to Lewis base sites, which has a stronger anchoring effect on the metal nano ions, thereby helping the better dispersion of the nano ions. The loading amount of the Ru and Mo metals is not more than 3wt%, which can effectively reduce the cost.

[0031] (2) The catalyst can be used to catalytically prepare cyclohexane dialkyl dicarboxylate from dialkyl phthalate, because Mo can modify the Ru / N-γ-Al2O3 catalyst, and in the H2 atmosphere in the product application process, there is a hydrogen overflow effect between Ru-Mo metal particles, so that H2 is more easily activated. The introduction of Mo not only greatly improves the activity of the catalyst, but also reduces the amount of active component Ru. After the reaction is completed, the composition of the catalyst changes little and still maintains high activity, can be recycled and reused, and is conducive to large-scale industrial production. DETAILED DESCRIPTION

[0032] To better illustrate the purpose, technical solution and advantages of the present application, the present application will be further described below in conjunction with specific examples.

[0033] Example 1

[0034] The preparation method of the bimetallic Ru-Mo / γ-Al2O3 catalyst comprises the following steps:

[0035] (1) 5 g of γ-Al2O3 is added to 50 ml of an ammonia solution, the concentration of the ammonia water is 10 mol / L, stirring is carried out at 60℃ for 6 h, and N-γ-Al2O3 is obtained by drying in a 120℃ oven.

[0036] (2) A mixed solution of 1% RuCl3 solution and 0.2% Mo(NO3)2 solution by mass concentration is sprayed on the dried N-γ-Al2O3, stirring is carried out for 5 h, standing is carried out for 8 h, drying is carried out overnight at 110℃, and then deionized water is used for washing to remove chlorine ions, and then calcination is carried out at 500℃ in a muffle furnace for 2 h, and then reduction reaction is carried out at 200℃ in a tube furnace under a hydrogen atmosphere for 3 h, to obtain 1% Ru-0.2% Mo / N-γ-Al2O3.

[0037] Example 2

[0038] The catalyst of Example 2 is different from that of Example 1 in that the mass fraction of 0.5% Mo(NO3)2 is sprayed on the carrier in Example 2.

[0039] Example 3

[0040] The catalyst of Example 3 is different from that of Example 1 in that the mass fraction of 1% Mo(NO3)2 is sprayed on the carrier in Example 3.

[0041] Comparative Example 1

[0042] The catalyst of Comparative Example 1 is different from that of Example 1 in that the carrier N-γ-Al2O3 is not sprayed with RuCl3 and Mo(NO3)2 in step (2) of Comparative Example 1.

[0043] Comparative Example 2

[0044] The catalyst of Comparative Example 2 differs from Example 1 in that in step (2) of Comparative Example 2, only 1% RuCl3is sprayed on the carrier N-γ-Al2O3.

[0045] Comparative Example 3

[0046] The catalyst of Comparative Example 3 differs from Example 1 in that in Comparative Example 3, the γ-Al2O3used in step (1) is replaced by SiO2.

[0047] Comparative Example 4

[0048] The catalyst of Comparative Example 4 differs from Example 1 in that in step (2) of Comparative Example 4, Cr(NO3)2is used instead of Mo(NO3)2.

[0049] Comparative Example 5

[0050] The catalyst of Comparative Example 5 differs from Example 1 in that in step (2) of Comparative Example 5, Fe(NO3)2is used instead of Mo(NO3)2.

[0051] Examples 1-3 and Comparative Examples 1-5

[0052] Examples 1-3 and Comparative Examples 1-5

[0053] Examples 1-3 and Comparative Examples 1-5 -1 The catalyst of Comparative Example 4 differs from Example 1 in that in step (2) of Comparative Example 4, Cr(NO3)2is used instead of Mo(NO3)2.

[0054] Table 1 Performance of each catalyst in the preparation of diisononyl cyclohexane dicarboxylate

[0055]

[0056] From Table 1, it can be seen that the bimetallic supported catalysts prepared in Examples 1-3 can be used for the hydrogenation reaction to prepare diisononyl cyclohexane dicarboxylate, and the selectivity of the target acid product is higher, which can reach more than 99.5%. The catalyst used in Comparative Example 2 has no Mo(NO3)2 added, resulting in a decrease in the conversion rate of hexahydrophthalic anhydride, and the selectivity of diisononyl cyclohexyl dicarboxylate is reduced to 92.3%.

[0057] The catalyst used in Comparative Example 3 has SiO2 as the carrier, resulting in a decrease in the conversion rate of hexahydrophthalic anhydride, and the selectivity of diisononyl cyclohexyl dicarboxylate is reduced to 83.4%, indicating that the carrier of N-γ-Al2O3 is an important parameter for the selectivity of the catalyst in the hydrogenation reaction.

[0058] The Cr and Fe metals selected in Comparative Examples 4-5 replace Mo, and the selectivity of diisononyl cyclohexyl dicarboxylate is reduced to 62.8% and 65.3%. It is shown that the catalyst of the technical solution is selected by combining Mo and Ru to improve the selectivity of diisononyl cyclohexyl dicarboxylate. Moreover, the catalyst of the present application is easy to separate and recover from the product after the reaction, simplifying the process operation flow, and also has industrial application value.

[0059] Application of the recycled catalyst of Example 2

[0060] The catalyst of Example 2 is recycled for 1 time, 5 times, 10 times and 20 times according to the method of Application Example 2, respectively, and the conversion rate of diisononyl phthalate and the selectivity of diisononyl cyclohexyl dicarboxylate are detected. See Table 2 for details. Among them, the recovery method is: the catalyst after reaction is cleaned with cyclopentyl methyl ether for 3 times by ultrasonic shaking.

[0061] Table 2 Performance parameters of the recycled catalyst of Example 2

[0062]

[0063] From Table 2, it can be seen that after the reaction is completed, the composition of the catalyst changes little, and even after 20 times of recycling, the catalyst still maintains high activity and can be recycled and reused, which is beneficial to industrial large-scale production.

[0064] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and do not limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A method for preparing a bimetallic Ru-Mo / γ-Al2O3 catalyst, characterized in that, Includes the following steps: (1) Mix γ-Al2O3 with ammonia water and dry to obtain N-γ-Al2O3 support; (2) Ruthenium salt and molybdenum salt are loaded onto an N-γ-Al2O3 support, washed, calcined, and then reduced to obtain the bimetallic Ru-Mo / γ-Al2O3 catalyst; wherein the mass content of ruthenium in the catalyst is 0.1~2wt% and the mass content of molybdenum is 0.1~2wt%; The mass ratio of γ-Al2O3 to ammonia is 1:(5~10). The roasting temperature is 400~600℃.

2. The method for preparing the bimetallic Ru-Mo / γ-Al2O3 catalyst as described in claim 1, characterized in that, In step (1), the concentration of the ammonia water is 5~15 mol / L.

3. The method for preparing the bimetallic Ru-Mo / γ-Al2O3 catalyst as described in claim 1, characterized in that, In step (1), the mixing temperature is 55~65℃ and the time is 5~7h; the drying temperature is 110~125℃.

4. The method for preparing the bimetallic Ru-Mo / γ-Al2O3 catalyst as described in claim 1, characterized in that, The ruthenium salt solution is one of RuCl3 solution and Ru(NO3)3 solution; the molybdenum salt solution is one of Mo(NO3)2 solution and MoCl2 solution.

5. The method for preparing the bimetallic Ru-Mo / γ-Al2O3 catalyst as described in claim 1, characterized in that, The calcination time is 2-5 hours; the reduction reaction temperature is 200-300℃, and the reduction reaction time is 3-5 hours.

6. A bimetallic Ru-Mo / γ-Al2O3 catalyst, characterized in that, It is prepared by the method for preparing the bimetallic Ru-Mo / γ-Al2O3 catalyst according to any one of claims 1 to 5.

7. The use of the bimetallic Ru-Mo / γ-Al2O3 catalyst according to claim 6 in the preparation of dialkyl cyclohexanedicarboxylate.

8. The application of the bimetallic Ru-Mo / γ-Al2O3 catalyst according to claim 7, characterized in that, The preparation of dialkyl cyclohexanedicarboxylate includes the following steps: Using dialkyl phthalate and hydrogen as raw materials, a catalytic hydrogenation reaction is carried out in the presence of the bimetallic Ru-Mo / γ-Al2O3 catalyst to obtain the dialkyl cyclohexanedicarboxylate.

9. The application of the bimetallic Ru-Mo / γ-Al2O3 catalyst as described in claim 8, characterized in that, The catalytic hydrogenation reaction temperature is 130~150℃, and the reaction pressure is 3.0~5.0MPa; the liquid hourly space velocity (LHSV) of the dialkyl phthalate is 0.1~2h. -1 .

10. The application of the bimetallic Ru-Mo / γ-Al2O3 catalyst as described in claim 8 or 9, characterized in that, At least one of the following (I) to (III): (I) The dialkyl phthalate is at least one of diisononyl phthalate, di(2-ethylhexyl) phthalate, diisooctyl phthalate and dibutyl phthalate; (II) The molar ratio of hydrogen to the dialkyl phthalate is (5~10):1; (III) The amount of the bimetallic Ru-Mo / γ-Al2O3 catalyst added is 2%-8% of the raw material mass.

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