CN116196938B - Preparation method of efficient ruthenium-based catalyst - Google Patents

Abstract

The invention provides a preparation method of a high-efficiency Ru-based catalyst, which is applied to preparing cyclohexene by partial hydrogenation of benzene. Unlike traditional benzene partial hydrogenation in which an autoclave is used as a reactor, a fixed bed is used as an evaluation device. This will facilitate separation of the catalyst from the product and more convenient for continuous production. The catalyst can obtain 48.0 mol% yield under the optimal composition condition, which is improved by about 87.8% compared with a blank sample, and the yield is similar to that in an autoclave reactor. This is mainly due to the fact that the addition of Cu enhances the adsorption capacity of benzene and weakens the adsorption strength of cyclohexene, so that cyclohexane is prevented from being generated by excessive hydrogenation of cyclohexene. In addition, the Ru content of the catalyst used in the method is far lower than that of a non-supported Ru-based catalyst which is commonly used in industry (the Ru load of metal is 80 wt% -90.0 wt%). The catalyst production cost is greatly reduced, and the large-scale popularization and application are facilitated.

Description

Preparation method of efficient ruthenium-based catalyst

Technical Field

The invention belongs to the technical field of chemical industry, and particularly relates to a preparation method of a high-efficiency ruthenium-based catalyst.

Background

Cyclohexene is an important organic synthesis intermediate and fine chemical products, can be used as raw materials for preparing adipic acid, cyclohexylformic acid, cyclohexene oxide and the like in the pharmaceutical industry, is commonly used as an extractant and a stabilizer of high-octane gasoline in the petroleum industry, can be further hydrated under the action of an inorganic acid, an acidic oxide, a heteropoly acid and other acidic catalysts to generate cyclohexanol, and can be dehydrogenated to generate cyclohexanone which reacts with ammonia gas and hydrogen peroxide under the action of a titanium-silicon molecular sieve to prepare cyclohexanone oxime and then rearranged to generate caprolactam under the action of fuming sulfuric acid, so that nylon-6 is synthesized. As shown in the following process route, in nylon-6 production, compared with the traditional method for preparing cyclohexane by completely hydrogenating benzene and preparing cyclohexanol by free radical oxidation, the method for preparing cyclohexene by benzene selective hydrogenation can save 1/3 hydrogen consumption, reduce expensive unit operation cost, generate no waste liquid such as acid, ester and the like, reduce corrosion to equipment, and only byproduct cyclohexane can be reused, so that the method has the advantages of short flow, few steps, high yield and the like. In the current domestic caprolactam, the capacity of cyclohexene hydration method is more than half. The industrial cyclohexene production method mainly comprises benzene partial hydrogenation, cyclohexane dehydrogenation, cyclohexanol dehydration, halogenated cyclohexane dehydrohalogenation and Birch reduction. Compared with the prior art, the method for preparing cyclohexene by partial hydrogenation of benzene has the advantages of easily available raw materials, simple reaction route, simple operation and the like.

Cyclohexanone (full arrow) and cyclohexene in the above formula replace the standard industrial synthetic route (dashed arrow) for the synthesis of nylon-6.

Ruthenium-based catalysts are commonly used for the preparation of cyclohexene by partial hydrogenation of benzene. In order to improve the cyclohexene yield, proper auxiliary agents are generally required to be added so as to improve the surface hydrophilicity and Lewis acidity of the catalyst and promote the dispersion of active sites and the generation of electron-deficient Ru species. For example, zhou et al [ Zhou gongbing, et al journal of catalysis 2014;311:393-403] the addition of auxiliary B to Ru/ZrO ₂ has been found to increase the Lewis acidity of the catalyst surface from 38% to 48% by the addition of B. Zhou et al [ Zhou gongbing, et al Chemccathem 2013;5:2425-2435] it was found that treatment of the RuZn/ZrO ₂ catalyst with NaOH solution increased the hydrophilicity of the catalyst surface, increasing the cyclohexene yield from 38% to 51%. Zhou et al [ Zhou gongbing, et al Chemccathem 2018;10:1184-1191] the RuZn/ZrO ₂ catalyst is treated with acid to remove most Zn, and the residual of a small amount of Zn can greatly improve the cyclohexene yield. Besides addition of auxiliary agents, the special catalyst structure can also improve cyclohexene yield. For example, chen et al [ CN 201910076211.6] construct a core-shell structure to obtain a higher cyclohexene yield. Song et al [ Song yihui, et al, chemcathem 2022;1-11 is doped with Zn in LiAl hydrotalcite, then Ru is loaded on the LiAl hydrotalcite for preparing cyclohexene by partial hydrogenation of benzene, and a Ru ⁰/Ru^δ+ -O-Zn special structure is constructed, wherein the highest yield of cyclohexene can reach 43%. In summary, although the cyclohexene yield can be improved by adopting different strategies, the defect of low cyclohexene yield still exists, and how to stably improve the cyclohexene yield to more than 50% is the primary target of the process research. In addition, in the above patent and literature, an autoclave was used as a reaction evaluation device. The device increases the contact time of reactants and the catalyst, and can improve the cyclohexene yield, but has the defects of inconvenient continuous production, re-separation of the catalyst and the product after the reaction, and the like. Therefore, solving the continuous production of the reaction is also the focus of the process research.

Disclosure of Invention

The invention aims to provide a high-efficiency ruthenium-based catalyst, a preparation method and application thereof, and the provided catalyst has the characteristics of high target product yield, capability of adapting to the requirements of a fixed bed reactor and the like.

In order to achieve the above object, the present invention provides the following technical solutions:

(1) ZrOCl ₂·8H₂ O and H ₃BO₃ are precipitated under alkaline conditions, dried and roasted to obtain the B-doped ZrO ₂, and the B-doped ZrO ₂ is marked.

(2) Ru and Cu are loaded into B-ZrO ₂ by adopting an immersion method, after stirring and drying overnight, KBH ₄ is added, and after washing, drying and roasting, the obtained Cu doped Ru-based catalyst is marked as Ru-Cu/B-ZrO ₂.

In some preferred embodiments, the precipitant in the step (1) is one or more of ammonia water, naOH, na ₂CO₃ and NaHCO ₃, the roasting temperature is 300-900 ℃, the roasting time is 2-4h, the drying temperature is 80-150 ℃, the drying mode is vacuum drying or air drying, and the doping amount of B is 0.2-5.0 wt%.

In some preferred embodiments, the temperature during the precipitation in step (1) is 80 ℃ to 120 ℃, and the stirring mode is magnetic stirring or mechanical stirring.

In some preferred embodiments, the Cu source in step (2) is Cu (one or more of NO ₃)₂,CuSO₄,Cu(acac)₂ and CuCl ₂) and the Ru source is one or more of RuCl ₃,Ru(NO)NO₃,Ru(CH₃COO)₃ and RuI ₃.

In some preferred embodiments, the roasting temperature in the step (2) is 300-500 ℃, the roasting time is 2-4 hours, the drying temperature is 80-150 ℃, the drying mode is vacuum drying or forced air drying, the Cu content is 0.1-5.0 wt%, and the Ru content is 5.0-15.0 wt%.

In some preferred embodiments, the method of impregnation in step (2) is one or more of co-impregnation and step impregnation.

The invention provides a preparation method of the Gao Xiaoliao-based catalyst and application of the Gao Xiaoliao-based catalyst in a reaction of preparing cyclohexene by partial hydrogenation of benzene.

The beneficial results of the invention are that:

The invention provides a preparation method of a high-efficiency ruthenium-based catalyst, which is applied to preparing cyclohexene by partial hydrogenation of benzene. The industrial production device used for the reaction is an autoclave, and has the defects of difficult separation of products and catalysts, frequent regeneration of the catalysts and the like. In addition, the non-supported Ru-based catalyst (the metal Ru load is 80-90.0 wt%) is commonly adopted in industry, and the catalyst has higher industrial application value by adding the transition metal Cu, so that the use amount of noble metal Ru can be reduced while higher cyclohexene yield is obtained. The method mainly benefits from the introduction of Cu, is beneficial to desorption of cyclohexene as a product, and avoids excessive hydrogenation of the product to generate cyclohexane.

Detailed Description

The invention provides a high-efficiency ruthenium-based catalyst which is applied to preparing cyclohexene by partial hydrogenation of benzene. In the invention, the content of noble metal Ru is lower than the reported value (10.0-90.0 wt%) of the current literature and is 5.0-15.0 wt%, the content of Cu is 0.1-5.0 wt%, and the reaction evaluation device is a fixed bed reactor, thus being beneficial to continuous production and avoiding the defects of difficult separation of products and catalysts, frequent regeneration of the catalysts and the like.

The invention provides a preparation method of the ruthenium-based catalyst, which comprises the following steps:

(1) ZrOCl ₂·8H₂ O and H ₃BO₃ are mechanically stirred for 12 hours under alkaline conditions to hydrolyze, and after the hydrolysis is completed, the products are centrifugally separated. In order to clean chloride ions, the product is centrifugally washed for a plurality of times until no sediment is generated in the AgNO ₃ solution by the supernatant clear liquid drops, and then dried at 130 ℃ overnight and baked at 800 ℃ for 5 hours, and the obtained product is the B doped ZrO ₂, and is marked as ZrO ₂ -B.

(2) The method comprises the steps of loading metal Ru and Cu on ZrO ₂ -B by an immersion method, specifically, dissolving Ru salt and Cu salt in deionized water, adding ZrO ₂ -B, uniformly stirring, stirring with a magnet at 80 ℃, evaporating to dryness, and drying the obtained product at 130 ℃ overnight for later use.

(3) Dispersing the product obtained in the step 2 in excessive water, and adding KBH ₄ dropwise to reduce metal Ru and Cu at room temperature under stirring. The molar ratio of KBH ₄ to Ru ³⁺ was 4:1. And (3) washing the obtained product by centrifugal filtration for multiple times, drying overnight at 130 ℃, and roasting at 400 ℃ to obtain the catalyst Ru-Cu/ZrO ₂ -B.

In the invention, the evaluation method for preparing cyclohexene by benzene partial hydrogenation comprises the following steps of: taking 0.1g of catalyst, loading the catalyst into a fixed bed reactor, after no leakage point is detected, introducing pure H ₂ into the reactor at 50 ml/min ^-1, reducing the mixture for 1H at 100 ℃, pumping a mixed solution of benzene with the benzene content of 30wt% and water into the reactor tube at the flow rate of 600 ml/H ^-1·g_cat ^-1 by using a high-pressure pump, simultaneously introducing pure H ₂,H₂ at the flow rate of 30 ml/min ^-1, and starting the reaction when the reaction temperature is raised to 150 ℃ and the reaction time is 48H. All products were analyzed on line by gas chromatography, the column was a PEG capillary column and the detector was FID.

Example 1

10G of ZrOCl ₂·8H₂ O is weighed, added into 100ml of water, mechanically stirred until the ZrOCl ₂·8H₂ O is completely dissolved, added with 0.122 to g H ₃BO₃, stirred until the ZrOCl is completely dissolved, added with ammonia water to adjust the pH value of the solution to 10, and then refluxed for 12 hours at 80 ℃ to completely hydrolyze the ZrOCl ₂·8H₂ O. After hydrolysis, the product is centrifugally separated, and in order to ensure that Cl ions are completely washed, the product is stirred, dispersed and centrifugally separated for a plurality of times until the upper layer separation liquid drops are not precipitated in AgNO ₃ solution. Finally, the washed precipitate is dried at 130 ℃ overnight and baked at 800 ℃ for 5 hours, and then the obtained precipitate is B-doped ZrO ₂, and is marked as ZrO ₂ -B. The doping amount of B was 0.2wt%.

1G of ZrO ₂ -B is weighed, added into 20ml of water, stirred and dispersed uniformly by a magnet, added with 0.103g of RuCl ₃ and 0.059g of Cu (NO ₃)₂·3H₂ O, stirred and evaporated to dryness at 80 ℃, the sample is crushed into powder after being evaporated to dryness, dried overnight at 130 ℃, dispersed into 20ml of water, added dropwise with 2mol/L KBH ₄ solution, the molar ratio of KBH ₄ to Ru ³⁺ is 4:1, reduced metals Ru and Cu, finally centrifugally washed for many times, dried and baked at 130 ℃ for many times, and the obtained catalyst Ru-Cu/ZrO ₂ -B is obtained, wherein the Ru load is 4.7wt% and the Cu load is 1.2wt%.

The above samples were subjected to evaluation of benzene partial hydrogenation activity under the conditions as described above, and the results of the catalytic activity test are shown in Table 1.

Example 2

The catalyst Ru-Cu/ZrO ₂ -B was prepared with reference to example 1, unlike example 1, the Cu loading in this example was 3.0wt%.

The above samples were subjected to evaluation of benzene partial hydrogenation activity under the conditions as described above, and the results of the catalytic activity test are shown in Table 1.

Example 3

The catalyst Ru-Cu/ZrO ₂ -B was prepared with reference to example 1, unlike example 1, in which the Cu loading was 5.0wt%.

The above samples were subjected to evaluation of benzene partial hydrogenation activity under the conditions as described above, and the results of the catalytic activity test are shown in Table 1.

Example 4

The catalyst Ru-Cu/ZrO ₂ -B was prepared with reference to example 1, in contrast to example 1, the precipitant used in this example for preparing ZrO ₂ -B was NaHCO ₃.

The above samples were subjected to evaluation of benzene partial hydrogenation activity under the conditions as described above, and the results of the catalytic activity test are shown in Table 1.

Example 5

The catalyst Ru-Cu/ZrO ₂ -B was prepared with reference to example 1, unlike example 1 where the Ru source was Ru (NO) NO ₃.

The above samples were subjected to evaluation of benzene partial hydrogenation activity under the conditions as described above, and the results of the catalytic activity test are shown in Table 1.

Example 6

Catalyst Ru-Cu/ZrO ₂ -B was prepared with reference to example 1, unlike example 1, the Cu source in this example was Cu (acac) ₂.

The above samples were subjected to evaluation of benzene partial hydrogenation activity under the conditions as described above, and the results of the catalytic activity test are shown in Table 1.

Example 7

Ru-Cu/ZrO ₂ -B was prepared according to example 1, except that the doping level of B in the present example ZrO ₂ -B was 0.3wt%.

The above samples were subjected to evaluation of benzene partial hydrogenation activity under the conditions as described above, and the results of the catalytic activity test are shown in Table 1.

Example 8

Ru-Cu/ZrO ₂ -B were prepared according to example 7, unlike example 7, the Cu loading in this example was 3.0wt%.

The above samples were subjected to evaluation of benzene partial hydrogenation activity under the conditions as described above, and the results of the catalytic activity test are shown in Table 1.

Example 9

Ru-Cu/ZrO ₂ -B were prepared according to example 7, unlike example 7, the Cu loading in this example was 5.0wt%.

The above samples were subjected to evaluation of benzene partial hydrogenation activity under the conditions as described above, and the results of the catalytic activity test are shown in Table 1.

Example 10

Ru-Cu/ZrO ₂ -B was prepared according to example 1, except that the doping level of B in the present example ZrO ₂ -B was 0.5wt%.

The above samples were subjected to evaluation of benzene partial hydrogenation activity under the conditions as described above, and the results of the catalytic activity test are shown in Table 1.

Example 11

Ru-Cu/ZrO ₂ -B were prepared according to example 10, unlike example 10, the Cu loading in this example was 3.0wt%.

The above samples were subjected to evaluation of benzene partial hydrogenation activity under the conditions as described above, and the results of the catalytic activity test are shown in Table 1.

Example 12

Ru-Cu/ZrO ₂ -B were prepared according to example 10, unlike example 10, the Cu loading in this example was 5.0wt%.

The above samples were subjected to evaluation of benzene partial hydrogenation activity under the conditions as described above, and the results of the catalytic activity test are shown in Table 1.

Comparative sample 1

Ru-Cu/ZrO ₂ -B were prepared according to example 1, unlike example 1, the Cu loading in this example was 0.0wt%.

The above samples were subjected to evaluation of benzene partial hydrogenation activity under the conditions as described above, and the results of the catalytic activity test are shown in Table 1.

Comparative sample 2

Ru-Cu/ZrO ₂ -B were prepared according to example 7, unlike example 7, the Cu loading in this example was 0.0wt%.

The above samples were subjected to evaluation of benzene partial hydrogenation activity under the conditions as described above, and the results of the catalytic activity test are shown in Table 1.

Comparison sample 3

Ru-Cu/ZrO ₂ -B were prepared according to example 10, unlike example 10, the Cu loading in this example was 0.0wt%.

The above samples were subjected to evaluation of benzene partial hydrogenation activity under the conditions as described above, and the results of the catalytic activity test are shown in Table 1.

To determine the elemental content of the above samples, the present patent conducted ICP-AES tests on the examples, and the results are shown in Table 2. It can be found from the table that the actual contents of all the samples Ru, cu and B are close to the theoretical values and are within the allowable error range. This indicates that the method used in this patent is not prone to metal loss. Table 1 shows the results of the test for the partial hydrogenation activity of benzene in the examples. It can be seen from the table that the addition of an appropriate amount of copper increases the catalyst conversion and the cyclohexene selectivity. This is mainly because the introduction of Cu can strengthen the adsorption capacity of benzene and weaken the adsorption of cyclohexene, thereby avoiding the generation of cyclohexane by transitional hydrogenation of cyclohexene. The addition of a proper amount of B leads to the improvement of cyclohexene selectivity, mainly because the introduction of B increases Lewis acidity of the catalyst surface [ Zhou gongbing, et al journal of catalysis 2014;311:393-403]. In the patent, the optimal embodiment can obtain 48.0mol percent of yield, which is improved by about 87.8 percent compared with a blank sample, and the yield in an autoclave reactor is approximately [Zhou gongbing,et al.Journal of catalysis 2014;311:393-403,Zhou gongbing,et al.Journal of catalysis 2015;332:119-126]. percent, which shows that the Ru-based catalyst can meet the requirement of a fixed bed reactor, and the cyclohexene production is more convenient and continuous while obtaining higher yield.

Table 1. Example elemental analysis results.

Table 2. Results of partial hydrogenation performance for benzene of examples.

The foregoing is merely illustrative of the preferred embodiments of this invention and it will be appreciated by those skilled in the art that variations and modifications may be made without departing from the principles of the invention.

Claims (5)

1. The application of the ruthenium-based catalyst in preparing cyclohexene by catalyzing benzene to be partially hydrogenated is characterized in that,

Loading 0.1 g ruthenium-based catalyst into a fixed bed reactor, after no leakage point is detected, introducing pure H ₂ into the reactor at 50ml min ^-1, reducing the mixture at 100 ℃ for 1H, pumping a mixed solution of benzene with benzene content of 30 wt% and water into a reaction tube at a flow rate of 600 ml H ^-1 gcat^-1 by using a high-pressure pump, simultaneously introducing pure H ₂,H₂ at a flow rate of 30ml min ^-1, and starting the reaction when the reaction temperature is raised to 150 ℃, wherein the reaction time is 48H;

The preparation method of the ruthenium-based catalyst comprises the following steps:

(1) Adding water into ZrOCl ₂•8H₂ O to dissolve, then adding H ₃BO₃, heating and refluxing under alkaline conditions, centrifuging, washing, drying and roasting the obtained product to obtain B-doped ZrO ₂, and marking as B-ZrO ₂;

(2) Loading metal Ru and Cu into a carrier B-ZrO ₂ by an impregnation method, drying overnight, adding water, reducing the obtained precipitate by KBH ₄, drying overnight, and roasting to obtain a Cu-doped Ru-based catalyst, wherein the Cu source is Cu (one or more of NO ₃)₂,CuSO₄ and CuCl ₂;

The doping amount of B is 0.2 wt% of ZrOCl ₂•8H₂ O, the loading amount of Ru is 4.7 wt%, and the loading amount of Cu is 1.2 wt%;

Or the doping amount of B is 0.3 wt% of ZrOCl ₂•8H₂ O, the loading amount of Ru is 4.7 wt%, and the loading amount of Cu is 1.2 wt%;

Or the doping amount of B is 0.3wt% of ZrOCl ₂•8H₂ O, the loading amount of Ru is 4.7. 4.7 wt%, and the loading amount of Cu is 3.0wt%.

2. The application of the ruthenium-based catalyst for preparing cyclohexene by catalyzing benzene to be partially hydrogenated according to claim 1, wherein the alkaline environment in the step (1) is an environment in which any one of ammonia water, naOH and Na ₂CO₃、NaHCO₃ is adopted to adjust the pH to 10-12.

3. The application of the ruthenium-based catalyst for preparing cyclohexene by catalyzing benzene to be partially hydrogenated, according to claim 1, wherein the reflux reaction temperature in the step (1) is 80-120 ℃ and the reaction time is 2 h-12 h; washing with water until no chloride ion is generated; the drying temperature is 120-150 ℃; the roasting temperature is 300-900 ℃ and the roasting time is 2 h-4 h.

4. The use of a ruthenium-based catalyst according to claim 1 for the preparation of cyclohexene by partial hydrogenation of benzene, wherein the Ru source in step (2) is one or more of RuCl ₃,Ru(NO)NO₃,Ru(CH₃COO)₃ and RuI ₃.

5. The use of a ruthenium-based catalyst according to claim 1 for preparing cyclohexene by partial hydrogenation of benzene, wherein in the step (2), the roasting temperature is 300 ℃ to 500 ℃, the roasting time is 2h ℃ to 4h, the drying temperature is 80 ℃ to 150 ℃, and the drying mode is vacuum drying or forced air drying.