Catalyst as well as preparation method and application thereof

Abstract

The invention relates to a catalyst and a preparation method and application thereof, the catalyst for preparing enol through selective hydrogenation of alkynol comprises a sulfur modified mesoporous carrier and active components loaded on the sulfur modified mesoporous carrier, the active components comprise Pd element, M element and X element, the M element is selected from at least one of Cu, Bi and Ag, the X element is selected from at least one of Cu, Bi and Ag, and the X element is selected from at least one of Cu, Bi and Ag. And the X element is selected from at least one of Se, P and N. The catalyst provided by the invention can significantly improve the selectivity and stability of preparation of enol by hydrogenation of alkynol, especially can realize efficient conversion under continuous reaction or low-temperature and low-pressure reaction, and meets the green and safe production standard of modern chemical industry.

Description

Technical Field

[0001] This invention relates to the field of fine chemical technology, and in particular to a catalyst, its preparation method, and its application. Background Technology

[0002] Terminal enols are an important class of fine chemical intermediates and raw materials, widely used in fragrances, pharmaceuticals, pesticides and polymer materials. For example, C10 alkynols and C20 alkynols contain both terminal carbon-carbon double bonds and hydroxyl groups in their molecular structure. They are chemically active and are key materials for synthesizing a variety of high value-added products.

[0003] Currently, one of the most critical and commonly used methods for industrial production of enols is the selective hydrogenation of the corresponding alkynyl alcohols. The core challenge of this technology lies in how to efficiently and selectively hydrogenate and reduce the alkyne functional group (-C≡C-) to the alkene functional group (-C=C-), while simultaneously avoiding excessive hydrogenation to form saturated alkanols and suppressing other side reactions (such as isomerization and condensation). To date, production technologies in this field have primarily relied on batch hydrogenation processes. This traditional process typically involves adding the alkynyl alcohol feedstock, solvent, and catalyst (such as a Lindlar-modified palladium-based catalyst or other noble metal catalyst) all at once in a high-pressure reactor, and then reacting it under specific temperature, pressure, and stirring conditions with hydrogen gas. After the reaction is complete, the catalyst is separated and the product is purified.

[0004] For example, patent CN111018672B discloses the use of Lindlar catalysts in the hydrogenation synthesis of linalool from C10 alkynols. Lindlar catalysts typically use lead acetate or quinoline as catalyst poisoning agents (inhibitors) to poison the over-hydrogenated active sites on the catalyst, thereby obtaining highly selective olefins. However, lead is a heavy metal with high biotoxicity and environmental persistence. The catalysts used are considered hazardous waste, and their treatment and recycling processes are complex and costly, which does not conform to the principles of modern green chemistry.

[0005] Patent CN117753435B discloses a Pd-Cu-metal / SiO2-acid-treated catalyst applied to the batch hydrogenation of 1,4-butynediol, with a low product selectivity of only 85%. Patent CN119462342A discloses a metal catalyst obtained by in-situ complexation of metal salt and ligand, which can efficiently convert residual dehydrolinalool in the reaction solution to linalool in a high-pressure reactor, obtaining highly selective linalool. Patent CN112225640B provides a method for preparing highly selective enols by using alkynols as reactants under acidic conditions, through the combined action of Lindlar catalyst and crown ether compound in a batch reactor. Patent CN110124742B discloses a catalyst prepared by adding metal salt or metal carbonyl compound and moderately poisoning part of the hydrogenation catalyst in a synthesis atmosphere, which can be used to partially hydrogenate alkynols to produce enols in a high-pressure reactor, obtaining a highly selective product. Although the catalysts mentioned above have high selectivity, they are all batch hydrogenation reactions. Existing batch hydrogenation processes often have a series of inherent and insurmountable defects such as low production efficiency and difficulty in scaling up, which seriously restrict production efficiency and economic benefits. Furthermore, batch processes inevitably cause mechanical wear and activity loss of catalysts during operation, resulting in high catalyst consumption per unit, which increases production costs and environmental burden.

[0006] Patent CN119684085A discloses a method for preparing linalool, which uses a fluidized bed reactor for hydrogenation. By adding an appropriate amount of additives containing Zn, Co, and Fe elements to the reaction raw materials, the degree of hydrogenation of the raw materials can be effectively controlled to improve the aroma of the product. However, the additive Lewis acid will catalyze the dehydration reaction of linalool at high temperature, resulting in substandard product purity. Before the hydrogenation reaction liquid is purified by distillation, it must be washed with an alkaline solution for deacidification treatment. The process is complex and costly.

[0007] Therefore, there is an urgent need in this field to develop a technical solution that can fundamentally solve all of the above problems at the same time. Summary of the Invention

[0008] Therefore, it is necessary to provide a catalyst, its preparation method, and its application to address the above problems. The catalyst can significantly improve the selectivity and stability of alkynyl alcohol hydrogenation to enol, especially in continuous reaction or low-temperature and low-pressure reaction to achieve efficient conversion, and meets the standards of modern chemical green and safe production.

[0009] A catalyst for the selective hydrogenation of alkynols to prepare enols, the catalyst comprising a sulfur-modified mesoporous support and an active component supported on the sulfur-modified mesoporous support, the active component comprising Pd, M, and X elements, wherein M is selected from at least one of Cu, Bi, and Ag, and X is selected from at least one of Se, P, and N.

[0010] In one embodiment, the catalyst satisfies at least one of the following conditions:

[0011] (1) In the active components, the mass ratio of Pd, M and X is 1:(0.1~1):(0.02~0.5);

[0012] (2) The mesoporous carrier in the sulfur-modified mesoporous carrier is selected from at least one of mesoporous silica, mesoporous carbon materials, and mesoporous alumina.

[0013] A method for preparing the catalyst as described above includes the following steps:

[0014] Step 1: The mesoporous support is immersed in a sulfur-containing solution and then dried, and then calcined in a protective gas to obtain a sulfur-modified mesoporous support.

[0015] Step 2: The sulfur-modified mesoporous support is placed in a palladium salt solution, and a first reduction reaction is performed to obtain a Pd-loaded sulfur-modified mesoporous support.

[0016] Step 3: Place the sulfur-modified mesoporous support loaded with Pd in ​​an M salt solution and undergo a second reduction reaction to obtain a sulfur-modified mesoporous support loaded with Pd-M.

[0017] Step 4: Place the sulfur-modified mesoporous support loaded with Pd-M in an aqueous solution containing X, and carry out a thermal reflux reaction under a protective gas to obtain the catalyst.

[0018] In one embodiment, step one satisfies at least one of the following conditions:

[0019] (1) The mesoporous carrier is selected from at least one of mesoporous silica, mesoporous carbon materials, and mesoporous alumina;

[0020] (2) The sulfur-containing solution is selected from at least one of ammonium sulfide aqueous solution, thiourea ethanol solution, and hydrogen sulfide ethanol solution;

[0021] (3) The mass of the solute in the sulfur-containing solution is 0.5% to 5% of the mass of the mesoporous carrier;

[0022] (4) The immersion temperature is 30℃~60℃, and the time is 2h~6h;

[0023] (5) The drying temperature is 100℃~120℃, and the time is 4h~6h;

[0024] (6) The calcination temperature is 200℃~600℃ and the time is 2h~6h.

[0025] In one embodiment, step two satisfies at least one of the following conditions:

[0026] (1) The loading amount of Pd on the sulfur-modified mesoporous support is 0.05wt%~0.4wt%;

[0027] (2) The palladium salt solution is selected from at least one of chloropalladium acid solution, sodium tetrachloropalladium solution, palladium chloride solution, and palladium nitrate solution;

[0028] (3) Before the first reduction reaction, the sulfur-modified mesoporous support is mixed with the palladium salt solution and stirred for 10 h to 24 h;

[0029] (4) The first reduction reaction is carried out by adding a first reducing agent, wherein the first reducing agent is selected from at least one of sodium formate, formic acid, hydrazine hydrate, ascorbic acid and formaldehyde, the mass ratio of the first reducing agent to palladium in the palladium salt solution is 1:(0.1~0.6), the temperature is 30℃~60℃, and the time is 1h~8h;

[0030] (5) After the first reduction reaction, the reduction product is dried at 80℃~120℃ for 10h~12h to obtain a sulfur-modified mesoporous support loaded with Pd.

[0031] In one embodiment, step three satisfies at least one of the following conditions:

[0032] (1) The loading amount of M on the sulfur-modified mesoporous support is 0.005wt%~0.4wt%;

[0033] (2) The M salt solution is selected from at least one of copper nitrate solution, silver nitrate solution, and bismuth nitrate solution;

[0034] (3) Before the second reduction reaction, the sulfur-modified mesoporous support loaded with Pd is mixed and stirred with the M salt solution at 40℃~70℃ for 10h~24h.

[0035] (4) The second reduction reaction is carried out by adding a second reducing agent, wherein the second reducing agent is selected from at least one of sodium formate, formic acid, hydrazine hydrate, ascorbic acid and formaldehyde, the mass ratio of the second reducing agent to M in the M salt solution is 1:(0.1~0.5), the mixing temperature is 30℃~60℃, and the time is 1h~8h;

[0036] (5) After the second reduction reaction, the reduction product is dried at 100℃~140℃ for 10h~20h to obtain sulfur-modified mesoporous support loaded with Pd-M.

[0037] In one embodiment, step four satisfies at least one of the following conditions:

[0038] (1) The loading amount of X on the sulfur-modified mesoporous support is 0.001wt%~0.2wt%;

[0039] (2) The aqueous solution containing X is selected from at least one of triphenylphosphine toluene solution, 2-methylimidazolium ethanol solution, and sodium selenide ethanol solution;

[0040] (3) The temperature of the heat reflux reaction is 60℃~80℃ and the time is 1h~4h;

[0041] (4) After the hot reflux reaction, the reaction product is cooled and dried to obtain the catalyst.

[0042] A method for selective hydrogenation of alkynyl alcohols to prepare enols involves hydrogenating alkynyl alcohols under the action of a catalyst as described above to obtain enols.

[0043] In one embodiment, hydrogen gas is introduced to react the alkynol with a portion of the catalyst until the conversion rate reaches 60% to 80%, and then the reaction product is reacted with the remaining catalyst to obtain an enol.

[0044] In one embodiment, at least one of the following conditions is met:

[0045] (1) The alkynol is selected from at least one of dehydrolinalool, dehydroisophytol, and 1,4-butynediol;

[0046] (2) The molar ratio of alkynol to hydrogen is 1:(2~10);

[0047] (3) The mass hourly space velocity of the reaction is 0.05 h⁻¹. -1 ~1.0h -1 ;

[0048] (4) The reaction system also includes an inhibitor, which is selected from at least one of carbon monoxide, sulfide, and sulfur-containing alkanes. When the inhibitor is selected from sulfide and / or sulfur-containing alkanes, the amount of inhibitor is 0.05% to 0.2% of the mass of alkynol. When the inhibitor is selected from carbon monoxide, the content of carbon monoxide in the hydrogen atmosphere is 10 ppm to 40 ppm.

[0049] (5) The reaction temperature is 30℃~85℃, the reaction pressure is 0.05MPa~0.3MPa, and the reaction time is 1h~10h.

[0050] The catalyst described in this invention achieves a dynamic balance of "rapid hydrogenation and strong desorption" by regulating the hydrogenation selectivity of Pd through a dual-site regulation of M and X sites. Simultaneously, it inhibits the aggregation and loss of the active component, thereby significantly improving the selectivity and stability of olefins in the triple bond half-hydrogenation reaction. Especially under low temperature and low pressure, it enables rapid conversion of feedstocks, avoiding the formation of polymers and perhydrogenated products, overcoming the shortcomings of traditional catalysts. Furthermore, the active component constructed in this invention reduces the active metal content, which is beneficial for achieving high conversion rates, high selectivity, and high stability of alkynol triple bonds in continuous reactions.

[0051] Therefore, using the catalyst described in this invention for the selective hydrogenation of alkynols to prepare enols is a novel method that combines a highly efficient and non-toxic catalyst system with a safe, precise, and easily scalable continuous flow hydrogenation process. This not only helps to reduce costs and increase efficiency, but also meets the standards for green and safe production in modern chemical industry. Detailed Implementation

[0052] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. In this invention, when referring to numerical ranges, unless otherwise specified, such ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Furthermore, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0054] This invention provides a catalyst for the selective hydrogenation of alkynols to prepare enols. The catalyst comprises a sulfur-modified mesoporous support and an active component supported on the sulfur-modified mesoporous support. The active component comprises Pd, M, and X elements, wherein M is selected from at least one of Cu, Bi, and Ag, and X is selected from at least one of Se, P, and N.

[0055] The catalyst described in this invention optimizes its composition and structure by combining M and X to form a dual-site regulation mechanism. While alloying M reduces the over-hydrogenation activity of Pd, surface coordination of X locks the olefin desorption pathway and shields non-selective sites. The two work synergistically to achieve a dynamic balance of "rapid hydrogenation and strong desorption," and inhibit the aggregation and loss of active components. This significantly improves the selectivity and stability of olefins in triple bond half-hydrogenation reactions, especially enabling rapid conversion of raw materials at low temperature and low pressure, avoiding the formation of polymers and over-hydrogenated products, thus overcoming the shortcomings of traditional catalysts.

[0056] Meanwhile, the active component constructed by this invention can also reduce the content of active metals, which is beneficial to achieving high conversion rate, high selectivity and high stability of alkynol triple bonds in continuous reactions, and can achieve a conversion rate of over 98% and a selectivity of over 97%.

[0057] Furthermore, compared with traditional catalysts containing toxic additives (such as Pb and Bi), the catalyst described in this invention is non-toxic, harmless, environmentally friendly, and meets the requirements for the development of green chemistry.

[0058] It should be noted that the active component refers to the complex formed by the mutual coordination and synergistic effect of Pd, M, and X, i.e., the Pd-MX complex. Preferably, M is selected from Cu, and X is selected from Se.

[0059] In one embodiment, the preferred mass ratio of Pd, M and X in the active component is 1:(0.1~1):(0.02~0.5). By adjusting the mass ratio of each component in the active component, it is beneficial to further improve the dynamic balance effect of "fast hydrogenation and strong desorption", thereby significantly improving the high conversion rate, high selectivity and high stability of alkynol triple bond.

[0060] It is understood that the mass ratio of Pd, M and X in the active components includes, but is not limited to, any one of the following values ​​or a range between any two: 1:0.1:0.02, 1:0.1:0.1, 1:0.1:0.2, 1:0.1:0.5, 1:0.5:0.02, 1:0.5:0.1, 1:0.5:0.2, 1:0.5:0.5, 1:1:0.02, 1:1:0.1, 1:1:0.2, 1:1:0.5.

[0061] Mesoporous supports can provide high specific surface area and stable pore structure, which is beneficial to enhancing the dispersibility and stability of active components.

[0062] In one embodiment, the mesoporous carrier in the sulfur-modified mesoporous carrier includes, but is not limited to, at least one of mesoporous silica, mesoporous carbon material, and mesoporous alumina, preferably mesoporous silica.

[0063] It is understood that sulfur-modified mesoporous carriers refer to the modification and grafting of sulfur-containing functional groups such as thiol (-SH) onto the surface of a mesoporous carrier, and this invention does not limit this; mesoporous carriers refer to porous materials with pore sizes between 2nm and 50nm.

[0064] This invention provides a method for preparing the catalyst as described above, comprising the following steps:

[0065] Step 1: The mesoporous support is immersed in a sulfur-containing solution and then dried, and then calcined in a protective gas to obtain a sulfur-modified mesoporous support.

[0066] Step 2: The sulfur-modified mesoporous support is placed in a palladium salt solution, and a first reduction reaction is performed to obtain a Pd-loaded sulfur-modified mesoporous support.

[0067] Step 3: Place the sulfur-modified mesoporous support loaded with Pd in ​​an M salt solution and undergo a second reduction reaction to obtain a sulfur-modified mesoporous support loaded with Pd-M.

[0068] Step 4: Place the sulfur-modified mesoporous support loaded with Pd-M in an aqueous solution containing X, and carry out a thermal reflux reaction under a protective gas to obtain the catalyst.

[0069] The preparation method provided by this invention breaks through the traditional path of loading X onto the surface of the support through physical adsorption or chemical bonding in conventional technology. In particular, in step four, X is directionally introduced into the coordination environment of Pd through a triple regulation method of anhydrous reaction medium, protective atmosphere and thermal reflux. Combined with the synergistic effect of Pd-M alloy phase and sulfur modified support, the performance is significantly improved.

[0070] In step one, the surface of the mesoporous support is modified using a sulfur-containing solution. On the one hand, this allows sulfur-containing functional groups such as thiol (-SH) to be grafted onto the surface of the mesoporous support, which can preposition the subsequent loading of Pd and M, and is conducive to the formation of a stable metal ion-support combination structure. On the other hand, the lone pair electrons of sulfur form a weak interaction with the hydroxyl groups on the support surface, occupying the active adsorption sites on the support surface, and repelling the binding of X to the support from both spatial and electronic levels, thus eliminating competitive interference for the coordination of X and Pd.

[0071] In one embodiment, the mesoporous carrier includes, but is not limited to, at least one of mesoporous silica, mesoporous carbon material, and mesoporous alumina, preferably mesoporous silica.

[0072] In one embodiment, the sulfur-containing solution includes, but is not limited to, at least one of ammonium sulfide aqueous solution, thiourea ethanol solution, and hydrogen sulfide ethanol solution, preferably ammonium sulfide aqueous solution.

[0073] In one embodiment, the mass of the solute in the sulfur-containing solution is 0.5% to 5% of the mass of the mesoporous carrier. By adjusting the mass ratio of the solute to the mesoporous carrier in the sulfur-containing solution, it is beneficial to further optimize the structure of the sulfur-modified mesoporous carrier.

[0074] In one embodiment, the impregnation temperature is preferably 30°C to 60°C, and the time is preferably 2h to 6h; and / or, the drying temperature is preferably 100°C to 120°C, and the time is preferably 4h to 6h; and / or, the calcination temperature is preferably 200°C to 600°C, and the time is preferably 2h to 6h.

[0075] By adjusting the preparation conditions, it is beneficial to further optimize the structure of the sulfur-modified mesoporous support. It is understood that calcination refers to the process carried out under inert gas or nitrogen conditions.

[0076] In step two, palladium ions in the palladium salt solution are reduced to metallic palladium through a reduction reaction and loaded onto the support, thereby obtaining a sulfur-modified mesoporous support loaded with Pd.

[0077] In one embodiment, the loading of Pd on the sulfur-modified mesoporous support is preferably 0.05wt% to 0.4wt%. Compared with the conventional technology where the Pd loading is >1%, the present invention can reduce the Pd loading to below 0.4wt%, which is beneficial to further optimize the conversion rate, selectivity and stability of alkynol triple bonds in continuous reactions.

[0078] It is understood that the loading of Pd on the sulfur-modified mesoporous support includes, but is not limited to, any one of the following values ​​or any range between 0.05wt%, 0.1wt%, 0.2wt%, 0.3wt%, and 0.4wt%.

[0079] In one embodiment, the palladium salt solution includes, but is not limited to, at least one of chloropalladium acid (H₂PdCl₄) solution, sodium tetrachloropalladium (Na₂PdCl₄) solution, palladium chloride solution, and palladium nitrate solution. It is understood that the present invention does not limit the solvent used in the palladium salt solution; organic solvents can be used, preferably alcohol solvents, including but not limited to ethanol.

[0080] In one embodiment, mixing and stirring the sulfur-modified mesoporous support with the palladium salt solution for 10 to 24 hours before the first reduction reaction is beneficial to improving the uniformity of the load.

[0081] In one embodiment, the first reduction reaction is carried out by adding a first reducing agent, wherein the first reducing agent is selected from at least one of sodium formate, formic acid, hydrazine hydrate, ascorbic acid, and formaldehyde, and the mass ratio of the first reducing agent to palladium in the palladium salt solution is 1:(0.1~0.6). Preferably, the first reducing agent is added in batches, specifically, the batch addition includes dropwise addition. It is understood that the present invention does not limit the rate of dropwise addition.

[0082] In one embodiment, after the first reduction reaction, the reduction product is dried at 80°C to 120°C for 10 to 12 hours to obtain a sulfur-modified mesoporous support loaded with Pd.

[0083] In step three, the sulfur-modified mesoporous support loaded with Pd is placed in an M salt solution, allowing M ions to adsorb onto the support surface. Through a second reduction reaction, the M ions are reduced to metallic M and loaded onto the support. On one hand, the thiol functional groups on the support surface can form weak coordination bonds with the M ions, anchoring them at specific sites on the support surface and forming a stable metal ion-support bond structure. On the other hand, the alloying of Pd and M not only helps reduce the excessive hydrogenation activity of Pd but also inhibits the aggregation and loss of active components, thereby improving the selectivity and stability of the catalyst. Furthermore, M is selected from Cu, Bi, and Ag, is non-toxic and harmless, environmentally friendly, and meets the requirements of green chemistry development.

[0084] In one embodiment, the loading amount of M on the sulfur-modified mesoporous support is 0.005wt%~0.4wt%. By adjusting the loading amount of M on the sulfur-modified mesoporous support, it is beneficial to further optimize the mutual coordination and synergistic effect between the components in the catalyst.

[0085] It is understood that the loading of M on the sulfur-modified mesoporous support includes, but is not limited to, any one of the following values ​​or any range between two: 0.005wt%, 0.01wt%, 0.1wt%, 0.2wt%, 0.3wt%, and 0.4wt%.

[0086] In one embodiment, the M salt solution includes, but is not limited to, at least one of copper nitrate solution, silver nitrate solution, and bismuth nitrate solution. It is understood that the present invention does not limit the solvent in the M salt solution and water can be used.

[0087] In one embodiment, before the second reduction reaction, the sulfur-modified mesoporous support loaded with Pd is mixed and stirred with the M salt solution at 40°C to 70°C for 10 to 24 hours.

[0088] In one embodiment, the second reduction reaction is carried out by adding a second reducing agent, wherein the second reducing agent is selected from at least one of sodium formate, formic acid, hydrazine hydrate, ascorbic acid, and formaldehyde, and the mass ratio of the second reducing agent to M in the M salt solution is 1:(0.1~0.5), the mixing temperature is 30℃~60℃, and the time is 1h~8h. Preferably, the second reducing agent is added in a manner including but not limited to batch addition, such as dropwise addition. It is understood that the present invention does not limit the rate of dropwise addition.

[0089] It is understood that the first reducing agent and the second reducing agent can be the same or different. The present invention does not limit this, but it is preferred that the same reducing agent be used in both reduction reactions.

[0090] In one embodiment, after the second reduction reaction, the separated product is dried at 100°C to 140°C for 10 to 20 hours to obtain a sulfur-modified mesoporous support loaded with Pd-M.

[0091] In step four, an anhydrous reaction medium and a thermal reflux reaction are carried out under a protective gas. The anhydrous reaction medium can prevent the hydrolysis of P source in X to generate phosphate ions, thereby preventing P from combining with the hydroxyl groups of the support to form loaded P. The protective gas can prevent the oxidation of X source. At the same time, thermal reflux can ensure the fluidity of the X-containing anhydrous solution and prevent the Pd-M alloy phase from reconstructing and falling off the support due to excessive temperature. This effectively achieves the precise coordination of X and Pd, and thus obtains a stable active component structure.

[0092] In one embodiment, the loading amount of X on the sulfur-modified mesoporous support is 0.001wt%~0.2wt%. By adjusting the loading amount of X on the sulfur-modified mesoporous support, it is beneficial to further optimize the mutual coordination and synergistic effect among the components in the catalyst.

[0093] It is understood that the loading of X on the sulfur-modified mesoporous support includes, but is not limited to, any one of the following values ​​or any range between two: 0.001wt%, 0.005wt%, 0.01wt%, 0.05wt%, 0.1wt%, 0.2wt%.

[0094] In one embodiment, the anhydrous aqueous solution containing X includes, but is not limited to, at least one of triphenylphosphine toluene solution, 2-methylimidazole ethanol solution, and sodium selenide ethanol solution. For example, when the anhydrous aqueous solution containing X is selected from triphenylphosphine toluene solution, the P atom in the molecular structure of triphenylphosphine has a lone pair of electrons and exhibits steric hindrance of the benzene ring, which allows it to form stable coordination bonds only with Pd, while the binding energy with Cu atoms is relatively low. This facilitates selective coordination of P to Pd at the molecular level, preventing P from binding to Cu or being loaded onto a support.

[0095] In one embodiment, the temperature of the thermal reflux reaction is 60°C to 80°C and the time is 1h to 4h. By adjusting the temperature and time of the thermal reflux, it is beneficial to further optimize the precise coordination of X and Pd.

[0096] In one embodiment, after the thermal reflux reaction, the reaction product is cooled and dried to obtain the catalyst.

[0097] This invention employs a "stepwise loading-in-situ coordination method" to precisely control the proportion and spatial distribution of each component, solving the problem of uneven component dispersion in the traditional impregnation method. Furthermore, it is simple to operate, operates under mild conditions, is easy to control, and is suitable for large-scale industrial production.

[0098] The present invention also provides a method for selective hydrogenation of alkynyl alcohols to prepare enols, wherein alkynyl alcohols are subjected to hydrogenation reaction under the action of the catalyst described above to obtain enols.

[0099] Using the catalyst described in this invention for the selective hydrogenation of alkynols to prepare enols is a novel method that combines a highly efficient and non-toxic catalyst system with a safe, precise, and easily scalable continuous flow hydrogenation process. This not only helps to reduce costs and increase efficiency, but also meets the standards for green and safe production in modern chemical industry.

[0100] In one embodiment, hydrogen gas is introduced to react the alkynol with a portion of the catalyst until the conversion rate reaches 60%–80%. The reaction product is then reacted with the remaining catalyst to produce an enol. This two-stage reaction allows for independent control of reaction conditions at each stage to adapt to the needs of initial and deep conversion, improving the yield of the target product, extending catalyst life, and providing operational flexibility. By controlling the reaction conditions in stages through two stages, the first stage can complete the main conversion at low temperature and low pressure, while the second stage only requires fine-tuning the conditions to handle trace amounts of unreacted alkynol. This helps to precisely suppress excessive hydrogenation and side reactions after the alkynyl bond is hydrogenated to the alkene bond, significantly improving the selectivity, yield, and process stability of the target enol. Furthermore, this reaction is carried out under solvent-free conditions, avoiding the energy consumption and cost of solvent separation and recovery, reducing the potential impact of solvents on catalyst activity and the environmental risks from ethanol volatilization, thus improving the process economy.

[0101] It should be noted that this invention does not limit the amount of catalyst used in the two-stage reaction. Preferably, a catalyst ratio of approximately 1:1 in the two-stage reaction is more conducive to industrial application.

[0102] In one embodiment, the alkynols include, but are not limited to, at least one of dehydrolinalool, dehydroisophytol, and 1,4-butynediol.

[0103] In one embodiment, the molar ratio of the continuously introduced alkynol to hydrogen is preferably 1:(2~10), including but not limited to any one of 1:2, 1:3, 1:5, 1:8, 1:10 or any range between the two.

[0104] In one embodiment, the mass hourly space velocity (HHSV) of the reaction is 0.05 h⁻¹. -1 ~1.0h -1 including but not limited to 0.05h -1 0.2h -1 0.4h -1 0.6h -1 0.8h -1 1.0h -1 Any point value in the range or any range between two values.

[0105] In one embodiment, the reaction system further includes an inhibitor selected from at least one of carbon monoxide, sulfide, and sulfur-containing alkanes. When the inhibitor is selected from sulfide and / or sulfur-containing alkanes, the amount of inhibitor used is 0.05% to 0.2% of the mass of the alkynol. When the inhibitor is selected from carbon monoxide, the content of carbon monoxide in the hydrogen atmosphere is 10 ppm to 40 ppm.

[0106] In one embodiment, the reaction temperature is 30℃~85℃, the reaction pressure is 0.05MPa~0.3MPa, and the reaction time is 1h~10h. Here, mass hourly space velocity (MHSV) refers to the ratio of feed mass to catalyst mass per unit time, reflecting the residence time of the material in the catalyst bed, and is a parameter for measuring feedstock processing efficiency in catalytic reactions.

[0107] It is understood that the present invention does not limit the apparatus for the selective hydrogenation of alkynols to prepare enols, but preferably adopts a continuous production apparatus, and more preferably two reactors connected in series.

[0108] The catalyst, its preparation method, and its application will be further illustrated below through specific embodiments. However, those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified, specific conditions in the embodiments were performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0109] Example 1

[0110] Take 100g of mesoporous silica support and add 200mL of 2wt% ammonium sulfide solution (the mass of ammonium sulfide is about 4% of the mass of the support). Impregnate at 50℃ for 4h. After impregnation, dry the sample in an environment of 100℃ for 4h, and then transfer it to a tube furnace and calcine at 400℃ for 4h under a nitrogen protective atmosphere to obtain sulfur-modified support.

[0111] Take 0.33 g of palladium chloride solid and place it in a container. Add an appropriate amount of pure water, then add concentrated hydrochloric acid dropwise while stirring until the palladium chloride is completely dissolved, forming a clear palladium chloride (H₂PdCl₄) solution. Finally, add water to make up to a total volume of 100 g and shake well. Then, add the sulfur-modified support to this solution, heat to 50 °C, and stir at 200 rpm for 12 h. Then, add 100 mL of 0.4 wt% sodium formate solution dropwise at a rate of 0.5 mL / min. After the liquid-phase reduction reaction is complete, dry the product at 100 °C for 10 h to obtain the Pd-loaded sulfur-modified support.

[0112] 0.117 g of copper nitrate was dissolved in 100 mL of water. The Pd-loaded sulfur-modified support was then added to the copper nitrate solution. The mixture was heated to 50 °C and stirred at 200 rpm for 12 h. Then, 50 mL of 0.4 wt% sodium formate solution was added dropwise at a rate of 0.5 mL / min. After the liquid-phase reduction reaction was complete, the product was dried at 100 °C for 10 h to obtain the Pd-Cu-loaded sulfur-modified support.

[0113] 0.026 g of sodium selenide was dissolved in 100 mL of ethanol. A sulfur-modified support loaded with Pd-Cu was then added to the sodium selenide solution. The mixture was refluxed at 65 °C for 4 h under nitrogen protection. After the reaction was complete, the mixture was cooled to room temperature and dried to obtain the catalyst.

[0114] Example 2

[0115] Take 100g of mesoporous silica support and add 200mL of 1.5wt% ammonium sulfide solution (the mass of ammonium sulfide is about 3% of the mass of the support). Impregnate at 55℃ for 5h. After impregnation, dry the sample at 120℃ for 5h, and then transfer it to a tube furnace and calcine at 450℃ for 5h under a nitrogen protective atmosphere to obtain sulfur-modified support.

[0116] Take 0.50 g of palladium chloride solid and place it in a container. Add an appropriate amount of pure water, then add concentrated hydrochloric acid dropwise while stirring until the palladium chloride is completely dissolved, forming a clear palladium chloride (H₂PdCl₄) solution. Finally, add water to make up to a total volume of 100 g and shake well. Then, add the sulfur-modified support to this solution, heat to 55 °C, and stir at 200 rpm for 16 h. Then, add 100 mL of 0.5 wt% sodium formate solution dropwise at a rate of 0.5 mL / min. After the liquid-phase reduction reaction is complete, dry the product at 120 °C for 11 h to obtain the Pd-loaded sulfur-modified support.

[0117] 0.176 g of copper nitrate was dissolved in 100 mL of water. The Pd-loaded sulfur-modified support was then added to the copper nitrate solution. The mixture was heated to 55 °C and stirred at 200 rpm for 16 h. Then, 50 mL of 0.5 wt% sodium formate solution was added dropwise at a rate of 0.5 mL / min. After the liquid-phase reduction reaction was complete, the product was dried at 120 °C for 10 h to obtain the Pd-Cu-loaded sulfur-modified support.

[0118] 0.039 g of sodium selenide was dissolved in 100 mL of ethanol. A sulfur-modified support loaded with Pd-Cu was then added to the sodium selenide solution. The mixture was refluxed at 70 °C for 3 h under nitrogen protection. After the reaction was complete, the mixture was cooled to room temperature and dried to obtain the catalyst.

[0119] Example 3

[0120] Take 100g of mesoporous silica support and add 200mL of 1wt% ammonium sulfide solution (the mass of the ammonium sulfide solution is approximately 2% of the mass of the support). Impregnate at 45℃ for 4.5h. After impregnation, dry the sample at 110℃ for 4.5h, then transfer it to a tube furnace and calcine at 500℃ for 6h under a nitrogen protective atmosphere to obtain the sulfur-modified support.

[0121] 0.17 g of palladium chloride solid was placed in a container, and an appropriate amount of pure water was added. Then, concentrated hydrochloric acid was added dropwise while stirring until the palladium chloride was completely dissolved, forming a clear palladium chloride (H₂PdCl₄) solution. Water was then added to bring the total volume to 100 g, and the solution was shaken well. The sulfur-modified support was then added to this solution, and the temperature was raised to 60 °C. The mixture was stirred at 200 rpm for 13 h, and then 100 mL of 0.3 wt% sodium formate solution was added dropwise at a rate of 0.5 mL / min. After the liquid-phase reduction reaction was completed, the product was dried at 110 °C for 12 h to obtain the Pd-loaded sulfur-modified support.

[0122] 0.059 g of copper nitrate was dissolved in 100 mL of water. The Pd-loaded sulfur-modified support was then added to the copper nitrate solution. The mixture was heated to 45 °C and stirred at 200 rpm for 13 h. Then, 50 mL of 0.3 wt% sodium formate solution was added dropwise at a rate of 0.5 mL / min. After the liquid-phase reduction reaction was complete, the product was dried at 110 °C for 13 h to obtain the Pd-Cu-loaded sulfur-modified support.

[0123] 0.013 g of sodium selenide was dissolved in 100 mL of ethanol. A sulfur-modified support loaded with Pd-Cu was then added to the sodium selenide solution. The mixture was refluxed at 60 °C for 2 h under nitrogen protection. After the reaction was complete, the mixture was cooled to room temperature and dried to obtain the catalyst.

[0124] Examples 4 to 15

[0125] The catalysts in Examples 4 to 15 were prepared using the same method as in Example 1. The specific differences are shown in Table 1.

[0126] Table 1

[0127]

[0128] Application Examples 1 to 15

[0129] The catalysts prepared in Examples 1-15 were applied to the continuous triple bond half-hydrogenation reaction of dehydrolinalool. The reaction was carried out in two stages, with 90 g of catalyst in each stage reaction tube. The feed flow rate of dehydrolinalool was 0.6 mL / min, the hydrogen flow rate was 100 mL / min, and the dehydrolinalool mass hourly space velocity was 0.34 h⁻¹. -1 (Mass hourly space velocity is calculated based on the amount of catalyst used in a single reactor). A thioether (3,6-dithia-1,8-octanediol) inhibitor was added to the reaction system at a dosage of 0.08% of the mass of dehydrolinalool. The reaction temperature in the first reactor was 45℃, and the reaction pressure was 0.3 MPa. After the conversion rate of dehydrolinalool reached 70% in the first reactor, it entered the second reaction tube to completely react the raw materials. The total reaction time was approximately 8 hours. Samples were taken for gas chromatography to determine the content of dehydrolinalool and linalool. The results are shown in Table 2.

[0130] Table 2

[0131]

[0132] Application Example 16

[0133] The catalyst prepared in Example 1 was used in the hydrogenation of dehydroisophytol to prepare isophytol. The reaction was carried out in two stages, with 100 g of catalyst in each stage reaction tube. During the reaction, the feed flow rate of dehydroisophytol was 0.3 mL / min, the hydrogen flow rate was 100 mL / min, and the dehydroisophytol mass hourly space velocity was 0.15 h⁻¹. -1 (Mass hourly space velocity is calculated based on the amount of catalyst used in a single reactor). A carbon monoxide inhibitor of 20 ppm (in the proportion of hydrogen) was added to the reaction system. The reaction temperature in the first reactor was 75℃, and the reaction pressure was 0.2 MPa. The reaction temperature in the second reactor was 85℃, and the reaction pressure was 0.2 MPa. After the dehydroisophytol entered the first reactor and the conversion rate was controlled to reach 70%, it entered the second reaction tube to completely react with the dehydroisophytol (conversion rate exceeding 99%), with a reaction time of approximately 10 hours. Samples were taken for gas chromatography to determine the content of dehydroisophytol and isophytol; the results are shown in Table 3.

[0134] Application Example 17

[0135] The catalyst prepared in Example 2 was used in the reaction of 1,4-butynediol to 1,4-butenediol. The reaction was carried out in two stages, with 60 g of catalyst in each stage reaction tube. During the reaction, the feed flow rate of 1,4-butynediol was 0.4 mL / min, the hydrogen flow rate was 100 mL / min, and the mass hourly space velocity (WHSV) of 1,4-butynediol was 0.45 h⁻¹. -1 (Mass hourly space velocity is calculated based on the amount of catalyst used in a single reactor). A sulfur-containing alkane (1-butyritin) inhibitor was added to the reaction system at a dosage of 0.15% of the mass of 1,4-butynediol. The reaction temperature in the first reactor was 45°C, and the reaction pressure was 0.3 MPa. The reaction temperature in the second reactor was 50°C, and the reaction pressure was 0.3 MPa. After the conversion rate of 1,4-butynediol in the first reactor was controlled to reach 60%, it entered the second reaction tube to completely react with 1,4-butynediol (conversion rate exceeding 99%). Samples were taken for gas chromatography to determine the contents of 1,4-butynediol and 1,4-butenediol. The results are shown in Table 3.

[0136] Table 3

[0137]

[0138] As shown in Tables 2 and 3, the catalyst exhibits high reactant conversion, product selectivity, and yield in the hydrogenation of dehydroisophytol to isophytol and the semi-hydrogenation of 1,4-butynediol to 1,4-butenediol, among other alkynols, to enols.

[0139] The catalyst was tested for stability using the reaction conditions of Application Example 1. During the test, the conversion rate and selectivity data were recorded every 300 hours. The results are shown in Table 4.

[0140] Table 4

[0141]

[0142] Comparing Tables 2 and 4, it can be seen that the catalyst provided by the present invention can maintain high activity, excellent stability, and long service life even after continuous evaluation for 3000 hours.

[0143] Comparative Example 1

[0144] The difference between Comparative Example 1 and Example 1 is that the sulfur-modified support loaded with Pd was directly used as the catalyst.

[0145] Comparative Example 2

[0146] The difference between Comparative Example 2 and Example 1 is that Cu was not incorporated into the catalyst; the catalyst was prepared by directly adding the sulfur-modified support loaded with Pd into the sodium selenide ethanol solution.

[0147] Comparative Example 3

[0148] The difference between Comparative Example 3 and Example 1 is that Se was not incorporated into the catalyst; instead, a sulfur-modified support loaded with Pd-Cu was used directly as the catalyst.

[0149] Comparative Example 4

[0150] The difference between Comparative Example 4 and Example 1 is that the mesoporous silica support was not modified with sulfur, but was directly loaded with Pd, Cu, and Se.

[0151] Comparative Example 5

[0152] The difference between Comparative Example 5 and Example 1 is that the mesoporous silica support was not modified with sulfur, but was directly subjected to Pd loading treatment.

[0153] Using the same method as in Application Example 1, the catalysts prepared in Comparative Examples 1 to 5 were applied to the continuous reaction of triple bond semi-hydrogenation of dehydrolinalool, and samples were taken for gas chromatography to determine the contents of dehydrolinalool and linalool. The results are shown in Table 5.

[0154] Table 5

[0155]

[0156] Comparing Tables 2, 3, and 5, it can be seen that the catalyst provided by this invention can significantly improve the selectivity and actual yield of alkynyl alcohol hydrogenation to olefins, especially for the olefin selectivity of dehydrolinalool semi-hydrogenation, which can reach more than 97% and the actual yield can reach more than 95%.

[0157] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0158] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A catalyst for the selective hydrogenation of alkynols to prepare enols, characterized in that, The catalyst comprises a sulfur-modified mesoporous support and an active component supported on the sulfur-modified mesoporous support. The active component comprises Pd, M, and X elements, wherein M is selected from at least one of Cu, Bi, and Ag, and X is selected from at least one of Se, P, and N.

2. The catalyst according to claim 1, characterized in that, The catalyst satisfies at least one of the following conditions: (1) In the active components, the mass ratio of Pd, M and X is 1:(0.1~1):(0.02~0.5); (2) The mesoporous carrier in the sulfur-modified mesoporous carrier is selected from at least one of mesoporous silica, mesoporous carbon materials, and mesoporous alumina.

3. A method for preparing the catalyst as described in claim 1 or 2, characterized in that, Includes the following steps: Step 1: The mesoporous support is immersed in a sulfur-containing solution and then dried, and then calcined in a protective gas to obtain a sulfur-modified mesoporous support. Step 2: The sulfur-modified mesoporous support is placed in a palladium salt solution, and a first reduction reaction is performed to obtain a Pd-loaded sulfur-modified mesoporous support. Step 3: Place the sulfur-modified mesoporous support loaded with Pd in ​​an M salt solution and undergo a second reduction reaction to obtain a sulfur-modified mesoporous support loaded with Pd-M. Step 4: Place the sulfur-modified mesoporous support loaded with Pd-M in an aqueous solution containing X, and carry out a thermal reflux reaction under a protective gas to obtain the catalyst.

4. The method for preparing the catalyst according to claim 3, characterized in that, Step one must satisfy at least one of the following conditions: (1) The mesoporous carrier is selected from at least one of mesoporous silica, mesoporous carbon materials, and mesoporous alumina; (2) The sulfur-containing solution is selected from at least one of ammonium sulfide aqueous solution, thiourea ethanol solution, and hydrogen sulfide ethanol solution; (3) The mass of the solute in the sulfur-containing solution is 0.5% to 5% of the mass of the mesoporous carrier; (4) The immersion temperature is 30℃~60℃, and the time is 2h~6h; (5) The drying temperature is 100℃~120℃, and the time is 4h~6h; (6) The calcination temperature is 200℃~600℃ and the time is 2h~6h.

5. The method for preparing the catalyst according to claim 3, characterized in that, Step two must satisfy at least one of the following conditions: (1) The loading amount of Pd on the sulfur-modified mesoporous support is 0.05wt%~0.4wt%; (2) The palladium salt solution is selected from at least one of chloropalladium acid solution, sodium tetrachloropalladium solution, palladium chloride solution, and palladium nitrate solution; (3) Before the first reduction reaction, the sulfur-modified mesoporous support is mixed with the palladium salt solution and stirred for 10 h to 24 h; (4) The first reduction reaction is carried out by adding a first reducing agent, wherein the first reducing agent is selected from at least one of sodium formate, formic acid, hydrazine hydrate, ascorbic acid and formaldehyde, the mass ratio of the first reducing agent to palladium in the palladium salt solution is 1:(0.1~0.6), the temperature is 30℃~60℃, and the time is 1h~8h; (5) After the first reduction reaction, the reduction product is dried at 80℃~120℃ for 10h~12h to obtain a sulfur-modified mesoporous support loaded with Pd.

6. The method for preparing the catalyst according to claim 3, characterized in that, Step 3 must satisfy at least one of the following conditions: (1) The loading amount of M on the sulfur-modified mesoporous support is 0.005wt%~0.4wt%; (2) The M salt solution is selected from at least one of copper nitrate solution, silver nitrate solution, and bismuth nitrate solution; (3) Before the second reduction reaction, the sulfur-modified mesoporous support loaded with Pd is mixed and stirred with the M salt solution at 40℃~70℃ for 10h~24h. (4) The second reduction reaction is carried out by adding a second reducing agent, wherein the second reducing agent is selected from at least one of sodium formate, formic acid, hydrazine hydrate, ascorbic acid and formaldehyde, the mass ratio of the second reducing agent to M in the M salt solution is 1:(0.1~0.5), the temperature is 30℃~60℃, and the time is 1h~8h; (5) After the second reduction reaction, the reduction product is dried at 100℃~140℃ for 10h~20h to obtain sulfur-modified mesoporous support loaded with Pd-M.

7. The method for preparing the catalyst according to claim 3, characterized in that, Step four must satisfy at least one of the following conditions: (1) The loading amount of X on the sulfur-modified mesoporous support is 0.001wt%~0.2wt%; (2) The aqueous solution containing X is selected from at least one of triphenylphosphine toluene solution, 2-methylimidazolium ethanol solution, and sodium selenide ethanol solution; (3) The temperature of the heat reflux reaction is 60℃~80℃ and the time is 1h~4h; (4) After the hot reflux reaction, the reaction product is cooled and dried to obtain the catalyst.

8. A method for selective hydrogenation of alkynols to prepare enols, characterized in that, Enols are prepared by hydrogenating alkynols under the action of the catalyst described in claim 1 or 2.

9. The method for selective hydrogenation of alkynols to prepare enols according to claim 8, characterized in that, Hydrogen gas is introduced to react the alkynol with part of the catalyst until the conversion rate reaches 60%~80%. The reaction product is then reacted with the remaining catalyst to obtain the enol.

10. The method for selective hydrogenation of alkynols to prepare enols according to claim 9, characterized in that, At least one of the following conditions must be met: (1) The alkynol is selected from at least one of dehydrolinalool, dehydroisophytol, and 1,4-butynediol; (2) The molar ratio of alkynol to hydrogen is 1:(2~10); (3) The mass hourly space velocity of the reaction is 0.05 h⁻¹. -1 ~1.0h -1 ; (4) The reaction system also includes an inhibitor, which is selected from at least one of carbon monoxide, sulfide, and sulfur-containing alkanes. When the inhibitor is selected from sulfide and / or sulfur-containing alkanes, the amount of inhibitor is 0.05% to 0.2% of the mass of alkynol. When the inhibitor is selected from carbon monoxide, the content of carbon monoxide in the hydrogen atmosphere is 10 ppm to 40 ppm. (5) The reaction temperature is 30℃~85℃, the reaction pressure is 0.05MPa~0.3MPa, and the reaction time is 1h~10h.

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