Method for regulating and controlling hydrogenation selectivity of styrene by double-metal doping

Abstract

The invention discloses a method for regulating and controlling hydrogenation selectivity of styrene by double-metal doping, which comprises the following steps: by taking MOF-808 as a model, synthesizing Pt nanoparticles in situ in a pore channel of the MOF-808 as an active center for hydrogenation of phenylacetylene, and replacing a part of Zr clusters of the MOF-808 with two different metals by a two-step microwave method to realize double-metal doping. The activity and the selectivity of phenylacetylene hydrogenation reaction are regulated and controlled under the conditions of normal temperature and normal pressure by adjusting the category and the proportion of bimetal, and finally high-activity conversion of phenylacetylene and high-selectivity product distribution of styrene are realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial catalysis, and particularly relates to a method for regulating the hydrogenation selectivity of styrene by dual-metal doping. Background Art

[0002] As an important basic organic chemical raw material, the main downstream products of styrene include polystyrene, styrene-butadiene rubber and various synthetic resins. With the growth of market demand for these chemical products, the output of styrene has increased year by year. The technology for extracting styrene from ethylene cracking C8 fraction is one of the relatively mature styrene preparation technologies at present. However, a small amount of phenylacetylene will inevitably be produced during the cracking process. Its chemical structure and properties are very similar to those of styrene, and it is difficult to separate. Therefore, it is crucial to convert phenylacetylene into styrene by hydrogenation. The hydrogenation products of phenylacetylene are styrene and ethane. Compared with styrene, the economic value of ethane is very low. Conventional catalysts for phenylacetylene hydrogenation often face the problem of over-hydrogenation to ethane and cannot stop at the styrene product. Therefore, the selectivity of the phenylacetylene hydrogenation reaction is crucial.

[0003] The existing selective hydrogenation catalysts are mainly based on precious metals such as platinum and palladium, and the content is relatively high, which makes the catalyst cost high. At the same time, the problem of catalyst deactivation is also very serious. In recent years, the emerging nanocatalysts are prone to agglomeration during use due to their high surface energy, resulting in a decrease in catalyst activity. Therefore, it is crucial to select a suitable support and confine the nanoparticle catalyst by a suitable method to ensure the durability of the catalyst. At the same time, the doping of non-precious metals has a great influence on the selectivity of the hydrogenation reaction. There is still no conclusion on how to select the type of doped non-precious metals and the doping ratio of non-precious metals, and further research is needed. Summary of the Invention

[0004] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this part, the abstract and the title, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0005] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0006] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for regulating the hydrogenation selectivity of styrene by dual-metal doping.

[0007] To solve the above technical problems, the present invention provides the following technical solution: A method for regulating the hydrogenation selectivity of styrene by dual-metal doping, characterized in that it includes:

[0008] Dissolve an organic ligand and a zirconium salt in a solvent, add a small molecule additive, heat, wash and dry after cooling to obtain a metal-organic framework material;

[0009] Disperse the metal-organic framework material in a solvent, add a platinum nanoparticle precursor and deionized water, perform ultrasonic treatment, wash and dry to obtain a black powder;

[0010] Disperse a metal ion precursor and the black powder in a solvent, perform microwave treatment, centrifuge, wash and dry.

[0011] As a preferred embodiment of the method of the present invention, wherein: dissolving the organic ligand and the central metal ion in a solvent, wherein the organic ligand is trimesic acid and the solvent is N,N-dimethylformamide.

[0012] As a preferred embodiment of the method of the present invention, wherein: adding the small molecule additive, wherein the small molecule additive is formic acid or glacial acetic acid.

[0013] As a preferred embodiment of the method of the present invention, wherein: heating, wherein the heating temperature is 100-120 °C and the heating time is 24 h.

[0014] As a preferred embodiment of the method of the present invention, wherein: dispersing the metal-organic framework material in a solvent, wherein the solvent is at least one of methanol, ethanol, and acetone.

[0015] As a preferred embodiment of the method of the present invention, wherein: the platinum nanoparticle precursor is a potassium chloroplatinate solution, the metal ion precursor is ferric chloride hexahydrate or cobalt chloride hexahydrate, the amount of ferric chloride hexahydrate used is 80-190 mg, and the amount of cobalt chloride hexahydrate used is 70-170 mg.

[0016] As a preferred embodiment of the method of the present invention, wherein: washing and drying after ultrasonic treatment, wherein the time of ultrasonic treatment is 40-60 min and the drying temperature is 80-100 °C.

[0017] As a preferred embodiment of the method of the present invention, wherein: dispersing the metal ion precursor and the black powder in a solvent, wherein the solvent is N,N-dimethylformamide.

[0018] As a preferred embodiment of the method of the present invention, wherein: microwave treatment, wherein the microwave treatment temperature is 90-110 °C and the time is 90-120 min.

[0019] As a preferred embodiment of the method of the present invention, it is as follows: for the centrifugation, washing, and drying, the centrifugation speed is 10,000 - 13,000 r / min, the washing solvent is methanol or ethanol, the drying temperature is 80 - 100 °C, and the drying time is 12 - 16 h.

[0020] Advantages of the present invention:

[0021] (1) The present invention can rapidly achieve the substitution of the Zr clusters of MOF-808 using the microwave method, and the doping is rapid and efficient.

[0022] (2) The present invention uses dual-metal doping to optimize the activity and selectivity of phenylacetylene hydrogenation, and realizes high-activity conversion and high selectivity to styrene under normal temperature and pressure.

[0023] (3) The present invention illustrates the respective effects of the dual metals through comparative experiments: doping the first metal Fe can effectively control the reaction selectivity, enabling the reaction product to stay at the desired styrene, and the second metal Co can improve the reaction activity, enabling the reaction substrate to be converted faster, and the reaction structure-activity relationship is studied. Description of the drawings

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0025] Figure 1 It is the catalytic reaction process in Example 6.

[0026] Figure 2 It is the comparison chart of the catalytic results of the examples. Detailed implementation manners

[0027] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe the detailed implementation manners of the present invention in conjunction with the embodiments of the specification.

[0028] Many specific details are set forth in the following description to facilitate a thorough understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0029] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0030] Raw materials used in the present invention: Unless otherwise specified, all drugs are of analytical grade. The manufacturers of zirconium oxychloride octahydrate, trimesic acid, potassium chloroplatinate, and phenylacetylene are Anaiji, the manufacturers of ferric chloride hexahydrate and cobalt chloride hexahydrate are McLean, and the manufacturers of solvents involved in the synthesis and reaction are Sinopharm.

[0031] The instruments used in the embodiments of the present invention are: a microwave hydrothermal synthesizer manufactured by Enix, and a gas chromatograph manufactured by Shimadzu GC-2014.

[0032] Example 1

[0033] (1) Preparation of MOF-808: 97 mg of zirconium oxychloride octahydrate and 21 mg of trimesic acid were dissolved in 3 ml of N,N-dimethylformamide, and then 3 ml of formic acid was added. The mixture was sealed and heated at 100°C for 24 hours. After cooling, the mixture was washed with N,N-dimethylformamide and acetone for 1 to 3 times, respectively, and dried at 80 to 100°C to obtain MOF-808.

[0034] (2) Preparation of MOF-808@Pt: 10 mg of MOF-808 was dispersed in 4 ml of ethanol, and 80 ul of 10 mg / ml potassium chloroplatinite solution and 600 ul of deionized water were added. The mixture was ultrasonically cleaned for 40 minutes and then centrifuged at 10,000-13,000 r / min for 3 times with ethanol or acetone. The mixture was dried at 80-100°C to obtain a black powder, which was recorded as MOF-808@Pt.

[0035] (3) Preparation of Fe-MOF-808-@Pt: 85 mg of ferric chloride hexahydrate and 30 mg of MOF-808@Pt were dispersed in 6 ml of N,N-dimethylformamide, microwaved at 100 °C for 2 h, centrifuged and washed at a speed of 10,000 to 13,000 r / min, and dried at 80 to 100 °C to obtain a red solid, which was recorded as Fe-MOF-808@Pt. Figure 2 As shown, the MOF crystal structure did not change after doping.

[0036] Example 2

[0037] In this example, 85 mg of ferric chloride hexahydrate in Example 1 was replaced with 75 mg of cobalt chloride hexahydrate, and the other conditions remained the same. The obtained sample was labeled as Co-MOF-808@Pt. The phenylacetylene hydrogenation reaction was the same as that in Example 1. As Figure 2 shown, the crystal structure of the doped MOF did not change.

[0038] Example 3

[0039] In this example, 30 mg of Fe-MOF-808-@Pt obtained in Example 1 and 75 mg of cobalt chloride hexahydrate were dispersed in 6 ml of N,N-dimethylformamide, and microwave-treated at 100 °C for 2 h, followed by centrifugation, washing, and drying. The obtained sample was denoted as FeCo-MOF-808@Pt. The acetylene hydrogenation reaction was the same as that in Example 1.

[0040] Example 4

[0041] In this example, 85 mg of ferric chloride hexahydrate in Example 1 was replaced with 170 mg of ferric chloride hexahydrate, and the other conditions were the same as those in Example 3. The obtained sample was denoted as Fe 2 Co-MOF-808@Pt. The acetylene hydrogenation reaction was the same as that in Example 1.

[0042] Example 5

[0043] In this example, 75 mg of cobalt chloride hexahydrate in Example 3 was replaced with 150 mg of cobalt chloride hexahydrate, and the other conditions were the same as those in Example 3. The obtained sample was denoted as FeCo 2 -MOF-808@Pt. The acetylene hydrogenation reaction was the same as that in Example 1.

[0044] Example 6

[0045] In this example, no second or third metal was doped, and only MOF-808@Pt was used for the experiment. The acetylene hydrogenation reaction was the same as that in Example 1.

[0046] Comparative Example 1

[0047] The difference between this example and Example 1 is that 85 mg of ferric chloride hexahydrate was replaced with 42 mg of ferric chloride hexahydrate, and the other steps were the same as those in Example 1. The obtained sample was labeled as Fe0.5-MOF-808@Pt. The phenylacetylene hydrogenation reaction was the same as that in Example 1

[0048] Comparative Example 2

[0049] The difference between this example and Example 3 is that 75 mg of cobalt chloride hexahydrate was replaced with 37 mg of cobalt chloride hexahydrate, and the other steps were the same as those in Example 3. The obtained sample was labeled as FeCo0.5-MOF-808@Pt.

[0050] Catalytic reaction:

[0051] Weigh 10 mg of the catalyst and place it in a round-bottom flask. Add 5 ml of ethanol and 15 μl of the reaction substrate phenylacetylene. Tie a hydrogen balloon to the bottle mouth and carry out the reaction at room temperature. The reaction results are as Figure 1 shown.

[0052] Table 1 Catalytic results

[0053] Serial number Catalyst Time (h) Conversion rate (%) a(％) b(％) Example 1 Fe-MOF-808@Pt 2 39.7 74.3 25.7 4 74.2 78.1 21.9 Example 2 Co-MOF-808@Pt 2 92.5 40.5 59.5 4 100.0 9.7 90.3 Example 3 FeCo-MOF-808@Pt 2 53.2 79.3 20.7 4 99.9 89.6 10.4 Example 4 <![CDATA[Fe 2 Co-MOF-808@Pt]]> 2 44.7 78.8 21.2 4 91.6 87.5 12.5 Example 5 <![CDATA[FeCo 2 -MOF-808@Pt]]> 2 72.6 70.2 29.8 4 100.0 41 59 Example 6 MOF-808@Pt 2 54.2 37.2 62.8 4 87.3 11.4 88.6 Comparative example 1 <![CDATA[Fe 0.5 -MOF-808@Pt]]> 2 47.2 50.3 59.7 4 80.1 64.4 35.6 Comparative example 2 <![CDATA[FeCo 0.5 -MOF-808@Pt]]> 2 51.7 77.2 22.8 4 83.6 79.7 20.3

[0054] In Example 6, undoped-metal MOF-808@Pt has neither high activity nor selectivity for styrene in the hydrogenation reaction of phenylacetylene. After doping with Fe (Example 1), the reaction activity decreases, but the selectivity for styrene increases. The selectivity for styrene reaches 78.1% after 4 hours of reaction. This may be because Fe has a certain poisoning effect on the active center Pt nanoparticles. After doping with Co (Example 2), the reaction activity is greatly improved, and the phenylacetylene substrate can be basically converted within 2 hours. Instead, when the reaction continues, the originally formed styrene will continue to be hydrogenated to form ethane, indicating that the doping of Co can improve the activity of phenylacetylene hydrogenation, but it is impossible to control the reaction to stay at the styrene product. In Example 3, doping with Fe and Co respectively achieved good reaction activity and selectivity, and all the substrates were converted within 4 hours at normal temperature and pressure, and the selectivity for styrene reached 87.6%. In Examples 4 and 5, the doping ratios of Co and Fe were respectively regulated. It was further found that with the increase of the Fe content, the reaction activity and selectivity did not change significantly, while with the increase of the Co content, the reaction activity would be further improved, but it was also impossible to stop the reaction substrate at styrene, and the main product was over-hydrogenated ethane.

[0055] In this invention, the rapid substitution of the Zr clusters of MOF-808 is realized by the microwave method, and the doping is rapid and efficient; the activity and selectivity of phenylacetylene hydrogenation are optimized by dual-metal doping, and high-activity conversion and high selectivity to styrene are achieved at normal temperature and pressure; the respective effects of the dual metals are illustrated through comparative experiments: doping with the first metal Fe can effectively control the reaction selectivity and make the reaction product stay at the desired styrene, and the second metal Co can improve the reaction activity and make the reaction substrate be converted faster, and the reaction structure-activity relationship is studied.

[0056] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A method for regulating the selectivity of styrene hydrogenation by bimetallic doping, characterized in that: include, The organic ligand and the zirconium salt are dissolved in a solvent, a small molecule additive is added, the mixture is heated, cooled, washed and dried to obtain a metal organic framework material; The metal organic framework material is dispersed in a solvent, a platinum nanoparticle precursor and deionized water are added, and after ultrasonic treatment, the mixture is washed and dried to obtain a black powder. The metal ion precursor and the black powder are dispersed in a solvent, subjected to microwave treatment, centrifuged, washed, and dried.

2. The method according to claim 1, characterized in that: The organic ligand and the central metal ion are dissolved in a solvent, wherein the organic ligand is trimesic acid and the solvent is N,N-dimethylformamide.

3. The method according to claim 1, characterized in that: The small molecule additive is added, wherein the small molecule additive is formic acid or glacial acetic acid.

4. The method according to claim 1, characterized in that: The heating, wherein the heating temperature is 100-120° C., and the heating time is 24 hours.

5. The method according to claim 1, characterized in that: The metal organic framework material is dispersed in a solvent, wherein the solvent is at least one of methanol, ethanol and acetone.

6. The method according to claim 1, characterized in that: The platinum nanoparticle precursor is potassium chloroplatinite solution, the metal ion precursor is ferric chloride hexahydrate or cobalt chloride hexahydrate, the amount of ferric chloride hexahydrate is 80-190 mg, and the amount of cobalt chloride hexahydrate is 70-170 mg.

7. The method according to claim 1, characterized in that: The ultrasonic treatment is followed by washing and drying, wherein the ultrasonic treatment time is 40 to 60 minutes and the drying temperature is 80 to 100°C.

8. The method according to claim 1, characterized in that: The metal ion precursor and the black powder are dispersed in a solvent, wherein the solvent is N,N-dimethylformamide.

9. The method according to claim 1, characterized in that: The microwave treatment comprises a microwave treatment temperature of 90 to 110° C. and a microwave treatment time of 90 to 120 min.

10. The method according to claim 1, characterized in that: The centrifugation, washing and drying are as follows: the centrifugal speed is 10000-13000 r / min, the washing solvent is methanol or ethanol, the drying temperature is 80-100° C., and the drying time is 12-16 hours.

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