Core-shell ruthenium-carbon catalyst, preparation method and application thereof, and method for preparing sugar alcohol through catalytic reduction sugar hydrogenation

Abstract

The invention relates to the technical field of sugar alcohol preparation through sugar hydrogenation, in particular to a core-shell ruthenium-carbon catalyst, a preparation method and application thereof and a method for preparing sugar alcohol through catalytic reduction sugar hydrogenation. The core-shell ruthenium-carbon catalyst comprises a carrier and an active component coating the periphery of the carrier, the active component comprises ruthenium; the carrier comprises a porous carbon material; the porous carbon material comprises at least one of activated carbon, carbon black, aza-carbon or biochar; the content of the active component in the core-shell type ruthenium carbon catalyst is 0.5 wt%-3wt%. The core-shell ruthenium-carbon catalyst can promote the internal diffusion process of raw materials and products, is beneficial to removal of reaction heat, and shows good activity, selectivity and stability in the reaction of preparing sugar alcohol through catalytic hydrogenation of saccharides.

Description

Technical Field

[0001] The present invention relates to the technical field of preparing sugar alcohols by hydrogenation of sugars, and in particular to a core-shell ruthenium-carbon catalyst, a preparation method and an application thereof, and a method for catalytically hydrogenating reducing sugars to prepare sugar alcohols. Background Art

[0002] Sugar alcohols are polyhydric alcohols formed by reducing the carbonyl groups of aldoses and ketoses, mainly including sorbitol, xylitol, mannitol, etc., and are widely used as pharmaceutical excipients, sweeteners, and cosmetic additives. At the same time, sugar alcohols are also important organic synthesis intermediates and can be used to produce a variety of value-added chemicals such as vitamin C, polyurethane, isosorbide, and propylene glycol. In 2004 and 2010, "TOP12" and "TOP10" high-value-added bio-based platform compounds were proposed successively, and sorbitol and xylitol were both included. The synthesis methods of sugar alcohols mainly include microbial fermentation method, electrocatalytic reduction method, and catalytic hydrogenation method. The microbial fermentation method has mild process and low energy consumption, but has problems such as long production cycle, low yield, and high cost. The electrocatalytic reduction method has hydrogen evolution competition reaction, low conversion rate, and poor economy. The above two technologies are still mainly in the laboratory research stage and have low technology maturity. At present, catalytic hydrogenation method is mostly used to produce sugar alcohols at home and abroad.

[0003] At present, sugar alcohol production mainly adopts batch hydrogenation production process, using traditional Raney Ni as catalyst, and sugar hydrogenation reaction occurs at high temperature (≥120°C) and high pressure (3 MPa - 10 MPa) to generate corresponding sugar alcohols. This process is relatively mature, but there are the following challenges in hydrogenating sugars using a high-pressure reactor: (1) Low mass transfer efficiency and slow reaction rate: Sugar catalytic hydrogenation is a typical gas-liquid-solid three-phase reaction process with large mass transfer resistance and low production efficiency; (2) Poor selectivity and increased separation cost: Side reaction processes such as hydrogenolysis and isomerization often occur during the sugar hydrogenation process. The reaction conditions in the autoclave are harsh and there are large temperature gradients and residence time gradients, which will lead to an increase in by-products; (3) During the mechanical stirring process, the catalyst is easily damaged and has poor stability; (4) Poor process safety: A large amount of high-pressure hydrogen is retained in the reactor, and it is dangerous to disassemble the Raney Ni catalyst. Therefore, it is very important to develop a hydrogenation catalyst with high activity and high stability and a safe sugar alcohol production process to achieve highly selective and stable catalytic hydrogenation of sugars to produce sugar alcohols.

[0004] The patent with the publication number US5545674A discloses a method for preparing a core-shell catalyst by multiple sprayings. By repeatedly heating and spraying the carrier, the precursor solution rapidly evaporates on the surface of the carrier to form a core-shell catalyst. However, this method has complex operations and low production efficiency, and is not suitable for large-scale production. The patent with the publication number CN112742381A discloses a shell-layer distributed catalyst prepared by a spraying and impregnation method. A solution containing a film-forming polymer and a specific solvent are successively sprayed onto the carrier. After drying, a solution containing an active component is impregnated onto the treated carrier, and then calcined to obtain a shell-layer distributed catalyst. This catalyst has good application effects in Fischer-Tropsch synthesis reactions and hydrorefining reactions. However, there are few reports on the application of core-shell catalysts in sugar alcohol production. Additionally, in terms of hydrogenation reactors, the patent with the publication number CN109395672A discloses a fixed-bed reactor for sugar alcohol production, which is fixed by a metal framework to reduce mechanical loss of the catalyst. However, the catalyst preparation process is complex, the product yield is low (86.6% - 93.9%), and there are limitations on the raw material concentration. The patent with the publication number CN113956301A discloses a continuous sugar hydrogenation method with multiple reactors in series, which has high catalytic efficiency. However, the reactor pressure is as high as 8 MPa - 12 MPa, posing certain safety hazards. The patent with the publication number CN117209356A discloses a continuous preparation method of sugar alcohol based on a trickle-bed reactor. The reaction conditions are relatively mild (reaction temperature ≤ 130 °C, hydrogen pressure ≤ 8 MPa). However, the space-time yield is low, the catalyst has serious metal loss, resulting in poor stability, and there are heavy metal ions in the reaction solution, increasing the separation cost. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this purpose, the present invention provides a core-shell ruthenium-carbon catalyst, its preparation method and application, and a method for catalytic hydrogenation of reducing sugars to prepare sugar alcohols. This core-shell ruthenium-carbon catalyst can promote the internal diffusion process of raw materials and products, and is also beneficial to the removal of reaction heat. It shows good activity, selectivity and stability in the reaction of catalytic hydrogenation of sugars to prepare sugar alcohols. In addition, due to the use of this core-shell ruthenium-carbon catalyst, the method for catalytic hydrogenation of reducing sugars to prepare sugar alcohols has the advantages of high catalytic efficiency, good stability, mild reaction conditions, high product purity, small floor area, intrinsic safety, environmental friendliness, etc. It significantly reduces the reaction temperature and pressure, improves the space-time yield and selectivity, and provides a new solution for the value-added transformation of bio-based compounds.

[0006] For this purpose, the first aspect of the present invention provides a core-shell ruthenium-carbon catalyst, and the core-shell ruthenium-carbon catalyst includes a carrier and an active component coated on the outer periphery of the carrier;

[0007] The active component includes ruthenium;

[0008] The carrier includes a porous carbon material;

[0009] The porous carbon material includes at least one of activated carbon, carbon black, nitrogen-doped carbon, or biochar;

[0010] In the core-shell ruthenium-carbon catalyst, the content of the active component is 0.5 wt% to 3 wt%.

[0011] The core-shell ruthenium-carbon catalyst provided by the present invention has many advantages in the hydrogenation reaction. On the one hand, it can promote the internal diffusion process, accelerate the desorption of products, and improve the catalytic activity; on the other hand, it can shorten the reaction heat removal path, avoid the generation of hot spots, and reduce the generation of by-products.

[0012] According to an embodiment of the present invention, the particle size of the carrier is 50 μm to 1000 μm.

[0013] According to an embodiment of the present invention, the thickness of the shell layer formed by the active component is 20 μm to 200 μm.

[0014] The second aspect of the present invention provides a preparation method of the core-shell ruthenium-carbon catalyst described in the first aspect, including the following steps:

[0015] Spray the ruthenium salt solution onto the porous carbon material to obtain a precursor;

[0016] Reduce the precursor in a hydrogen atmosphere to obtain the core-shell ruthenium-carbon catalyst.

[0017] The core-shell ruthenium-carbon catalyst can be prepared by using the preparation method provided by the present invention, and the core-shell ruthenium-carbon catalyst has good activity, selectivity, and stability in the catalytic hydrogenation of sugars to prepare sugar alcohols.

[0018] According to an embodiment of the present invention, the content of ruthenium in the ruthenium salt solution is 0.01 wt% to 5 wt%.

[0019] According to an embodiment of the present invention, the spraying speed is 6 mL / h to 30 mL / h.

[0020] According to an embodiment of the present invention, the preparation method further includes: heating the porous carbon material and spraying the ruthenium salt solution onto the porous carbon material to obtain a precursor.

[0021] According to an embodiment of the present invention, the heating temperature is 50 °C to 120 °C.

[0022] According to an embodiment of the present invention, the reduction temperature is 200 °C to 400 °C.

[0023] According to an embodiment of the present invention, the reduction time is 1 h to 4 h.

[0024] In the third aspect of the present invention, there is provided an application of the core-shell ruthenium-carbon catalyst described in the first aspect or the core-shell ruthenium-carbon catalyst obtained by the preparation method according to the second aspect in the hydrogenation of reducing sugars to prepare sugar alcohols.

[0025] In the fourth aspect of the present invention, there is provided a method for catalyzing the hydrogenation of reducing sugars to prepare sugar alcohols, comprising the following steps:

[0026] Adding a reducing sugar solution and hydrogen into a micro-packed bed reactor for continuous hydrogenation reduction treatment to obtain sugar alcohols;

[0027] Wherein, the micro-packed bed reactor is filled with the core-shell ruthenium-carbon catalyst described in the first aspect or the core-shell ruthenium-carbon catalyst obtained by the preparation method according to the second aspect.

[0028] The method provided by the present invention can give full play to the excellent mass and heat transfer performance of the micro-packed bed reactor, and combined with the advantages of the core-shell catalyst, thereby significantly improving the catalytic efficiency and product selectivity, reducing the temperature and pressure of the process, and realizing safe, efficient and economical production of sugar alcohols.

[0029] According to an embodiment of the present invention, the content of reducing sugar in the reducing sugar solution is 10 wt% - 50 wt%.

[0030] According to an embodiment of the present invention, the reducing sugar includes aldose and / or ketose.

[0031] According to an embodiment of the present invention, the reducing sugar includes at least one of glucose, mannose, xylose, and fructose.

[0032] According to an embodiment of the present invention, the molar ratio of the reducing sugar to the hydrogen is 1:(1 - 3).

[0033] According to an embodiment of the present invention, the reaction pressure of the continuous hydrogenation reduction treatment is 0.5 MPa - 3.5 MPa.

[0034] According to an embodiment of the present invention, the reaction temperature of the continuous hydrogenation reduction treatment is 60 °C - 120 °C.

[0035] According to an embodiment of the present invention, the reaction time of the continuous hydrogenation reduction treatment is 30 s - 300 s.

[0036] According to an embodiment of the present invention, the sugar alcohol includes at least one of sorbitol, mannitol, and xylitol.

[0037] Advantages of the present invention over the prior art:

[0038] (1) Compared with existing catalysts, the core-shell ruthenium-carbon catalyst with adjustable shell thickness is prepared by the spraying method in the present invention, effectively realizing the strengthening of the internal diffusion process and the removal of reaction heat. The core-shell ruthenium-carbon catalyst exhibits high catalytic activity and excellent stability in the reaction of hydrogenating sugars to sugar alcohols, and the space-time yield of sugar alcohols can reach 1-30 g polyol / (g cat h), and the selectivity of the target product is high (92.2% - 99.9%).

[0039] (2) The present invention uses a micro-packed bed reactor to catalyze the hydrogenation of reducing sugars to sugar alcohols, making the reaction conditions milder. The hydrogen pressure is reduced from 4 MPa - 12 MPa to below 4 MPa, and the reaction temperature is reduced from above 120 °C to 60 - 120 °C. The reactor has a small volume and a small hydrogen retention amount, significantly improving the safety of the hydrogenation process.

[0040] (3) The shell layer of the core-shell catalyst provided by the present invention is uniform, and its preparation method is simple in operation, good in repeatability, wide in application range and easy to scale up, suitable for industrial application.

[0041] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. Detailed Embodiments

[0042] The embodiments of the present invention will be described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as a limitation of the present invention.

[0043] It should be noted that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Further, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0044] In the ranges disclosed herein, the endpoints and any value are not limited to the exact range or value, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values and individual point values of each range, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0045] To facilitate a better understanding of the present invention, certain technical and scientific terms are specifically defined below. Unless otherwise clearly defined elsewhere in this document, all other technical and scientific terms used herein shall have the meanings commonly understood by those of ordinary skill in the art to which the present invention pertains.

[0046] As used herein, the term "comprising" or "including" is an open-ended expression, meaning it includes the content specified in the present invention but does not exclude other aspects.

[0047] As used herein, the terms "optionally", "optional", or "option" generally refer to the subsequent event or condition that may or may not occur, and this description includes the cases where the event or condition occurs and the cases where it does not occur.

[0048] According to an embodiment of the present invention, a core-shell ruthenium-carbon catalyst is provided in a first aspect of the present invention. The core-shell ruthenium-carbon catalyst includes a carrier and an active component coated on the outer periphery of the carrier;

[0049] The active component includes ruthenium;

[0050] The carrier includes a porous carbon material;

[0051] The porous carbon material includes at least one of activated carbon, carbon black, nitrogen-doped carbon, or biochar;

[0052] The content of the active component in the core-shell ruthenium-carbon catalyst is 0.5 wt% to 3 wt%.

[0053] The core-shell ruthenium-carbon catalyst provided by the present invention has many advantages in the hydrogenation reaction. On the one hand, it can promote the internal diffusion process, accelerate the desorption of products, and improve the catalytic activity; on the other hand, it can shorten the reaction heat removal path, avoid the generation of hot spots, and reduce the generation of by-products. In addition, water is generally selected as the solvent for the catalytic hydrogenation of sugars. In an aqueous solution system, the stability of common oxide carriers such as alumina, titanium oxide, and silica is poor and will partially dissolve, thereby affecting the catalyst activity. However, the porous carbon material has good stability in an aqueous solution and good stability in a water-containing system.

[0054] According to a specific embodiment of the present invention, the particle size of the carrier is 50 μm to 1000 μm. As some specific examples, the particle size of the carrier can be 50 μm, 100 μm, 200 μm, 500 μm, 800 μm, 1000 μm, etc.

[0055] According to a specific embodiment of the present invention, the thickness of the shell layer formed by the active component is 20 μm to 200 μm. As some specific examples, the thickness of the shell layer formed by the active component can be 20 μm, 50 μm, 100 μm, 200 μm, etc.

[0056] According to an embodiment of the present invention, a second aspect of the present invention provides a method for preparing the core-shell ruthenium-carbon catalyst described in the first aspect, comprising the following steps:

[0057] (1) Spraying a ruthenium salt solution onto a porous carbon material to obtain a precursor.

[0058] According to a specific embodiment of the present invention, the content of ruthenium in the ruthenium salt solution is 0.01 wt% to 1 wt%. As some specific examples, the content of ruthenium in the ruthenium salt solution can be 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, etc.

[0059] According to a specific embodiment of the present invention, the type of the ruthenium salt is not particularly limited. As some specific examples, the ruthenium salt includes but is not limited to ruthenium trichloride.

[0060] According to a specific embodiment of the present invention, the type of the solvent of the ruthenium salt solution is not particularly limited. As some specific examples, the solvent includes at least one of water, methanol, and ethanol.

[0061] According to a specific embodiment of the present invention, the spraying speed is 6 mL / h to 30 mL / h. As some specific examples, the spraying speed can be 6 mL / h, 12 mL / h, 18 mL / h, 24 mL / h, 30 mL / h, etc.

[0062] According to a specific embodiment of the present invention, the preparation method further includes: heating the porous carbon material, and spraying the ruthenium salt solution onto the porous carbon material to obtain a precursor.

[0063] According to a specific embodiment of the present invention, the heating temperature is 50 °C to 120 °C. As some specific examples, the heating temperature can be 50 °C, 70 °C, 90 °C, 100 °C, 120 °C, etc. The shell thickness can be achieved by adjusting the concentration of the ruthenium salt solution and the heating temperature.

[0064] According to a specific embodiment of the present invention, the spraying equipment is not particularly limited. As some specific examples, the spraying equipment includes but is not limited to ultrasonic spraying equipment. The ruthenium salt solution can be atomized and uniformly sprayed onto the surface of the carrier through the ultrasonic spraying equipment.

[0065] According to a specific embodiment of the present invention, the heating method is not particularly limited. As some specific examples, the heating method includes but is not limited to heating by an infrared lamp.

[0066] According to a specific embodiment of the present invention, the preparation method further includes: uniformly rolling the porous carbon material through a rotating platform, heating the porous carbon material, and spraying a ruthenium salt solution onto the porous carbon material to obtain a precursor.

[0067] According to a specific embodiment of the present invention, the rotation speed of the rotating platform is 10 revolutions per minute to 100 revolutions per minute. As some specific examples, the rotation speed of the rotating platform can be 10 revolutions per minute, 20 revolutions per minute, 40 revolutions per minute, 60 revolutions per minute, 80 revolutions per minute, 100 revolutions per minute, etc.

[0068] (2) Reducing the precursor in a hydrogen atmosphere to obtain the core-shell ruthenium-carbon catalyst.

[0069] According to a specific embodiment of the present invention, the reduction temperature is 200°C to 400°C. As some specific examples, the reduction temperature can be 200°C, 300°C, 400°C, etc.

[0070] According to a specific embodiment of the present invention, the reduction time is 1 h to 4 h. As some specific examples, the reduction time can be 1 h, 2 h, 3 h, 4 h, etc.

[0071] Specifically, the reduction method of the precursor is not particularly limited and includes, but is not limited to, being carried out in a reducing atmosphere. The reducing atmosphere is not limited to hydrogen, and other reduction means can also be used, such as contacting with a reducing agent to achieve the reduction effect. The present invention has no particular limitation on the gas flow rate during reduction, and those skilled in the art can select according to actual needs.

[0072] According to an embodiment of the present invention, the third aspect of the present invention provides the application of the core-shell ruthenium-carbon catalyst described in the first aspect or the core-shell ruthenium-carbon catalyst obtained by the preparation method described in the second aspect in the hydrogenation of reducing sugars to prepare sugar alcohols.

[0073] According to an embodiment of the present invention, the fourth aspect of the present invention provides a method for catalytically hydrogenating reducing sugars to prepare sugar alcohols, including the following steps:

[0074] Adding a reducing sugar solution and hydrogen into a micro-packed bed reactor for continuous hydrogenation reduction treatment to obtain sugar alcohols;

[0075] Wherein, the micro-packed bed reactor is filled with the core-shell ruthenium-carbon catalyst described in the first aspect or the core-shell ruthenium-carbon catalyst obtained by the preparation method described in the second aspect.

[0076] Micro-packed bed reactors have advantages such as small volume, good mass and heat transfer performance, and precisely controllable residence time, and are widely used in heterogeneous catalytic reaction processes. Developing a continuous catalytic hydrogenation technology for sugars based on micro-packed bed reactors can give full play to the mass and heat transfer advantages of core-shell catalysts, improve the efficiency and safety of the reaction process, reduce the reaction temperature and pressure, significantly increase the space-time yield, improve the selectivity of target products, improve product quality, and achieve economical, safe, and green sugar alcohol production.

[0077] According to specific embodiments of the present invention, the content of reducing sugar in the reducing sugar solution is 10 wt% to 50 wt%. As some specific examples, the content of reducing sugar in the reducing sugar solution can be 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, etc.

[0078] According to specific embodiments of the present invention, the type of reducing sugar is not particularly limited. As some specific examples, the reducing sugar includes aldose and / or ketose, for example, includes at least one of glucose, mannose, xylose, and fructose.

[0079] According to specific embodiments of the present invention, the solvent of the reducing sugar solution is not particularly limited. As some specific examples, the solvent of the reducing sugar solution includes but is not limited to water.

[0080] According to specific embodiments of the present invention, the molar ratio of the reducing sugar to the hydrogen is 1:(1 to 3). As some specific examples, the molar ratio of the reducing sugar to the hydrogen can be 1:1, 1:2, 1:3, etc.

[0081] According to specific embodiments of the present invention, the reaction pressure of the continuous hydrogenation reduction treatment is 0.5 MPa to 3.5 MPa. As some specific examples, the reaction pressure of the continuous hydrogenation reduction treatment can be 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, etc.

[0082] According to specific embodiments of the present invention, the reaction temperature of the continuous hydrogenation reduction treatment is 60 °C to 120 °C. As some specific examples, the reaction temperature of the continuous hydrogenation reduction treatment can be 60 °C, 80 °C, 100 °C, 120 °C, etc.

[0083] According to specific embodiments of the present invention, the reaction time of the continuous hydrogenation reduction treatment is 30 s to 300 s. As some specific examples, the reaction time of the continuous hydrogenation reduction treatment can be 30 s, 50 s, 100 s, 150 s, 200 s, 250 s, 300 s, etc.

[0084] According to specific embodiments of the present invention, the types of the sugar alcohols are not particularly limited. As some specific examples, the sugar alcohols include at least one of sorbitol, mannitol, and xylitol.

[0085] According to specific embodiments of the present invention, the method further includes: adding a reducing sugar solution and hydrogen into a micro-packed bed reactor for continuous hydrogenation reduction treatment, and performing gas-liquid separation on the mixture obtained after the hydrogenation reaction in a gas-liquid separation tank, wherein the liquid product is separated and purified through filtration decolorization, ion exchange, and evaporation crystallization to obtain the sugar alcohol.

[0086] According to specific embodiments of the present invention, the micro-packed bed reactor includes a micro-mixer and a catalytic bed layer;

[0087] The micro-mixer is used to mix the reducing sugar solution and hydrogen to obtain a gas-liquid mixture;

[0088] The catalytic bed layer is connected to the micro-mixer, and the catalytic bed layer is filled with the core-shell ruthenium-carbon catalyst described in the first aspect or the core-shell ruthenium-carbon catalyst obtained according to the preparation method described in the second aspect, and the catalytic bed layer is used to cause the gas-liquid mixture to undergo a hydrogenation reduction reaction.

[0089] According to specific embodiments of the present invention, the types of the micro-mixers are not particularly limited. As some specific examples, the micro-mixers include, but are not limited to, T-shaped micro-mixers, Y-shaped micro-mixers, and membrane dispersion micro-mixers.

[0090] The solutions of the present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the embodiments regarding specific techniques or conditions, they shall be carried out according to the techniques or conditions described in the literature in the art or according to the product specifications. For the reagents or instruments not indicated with the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0091] Example 1

[0092] This example provides a method for preparing sorbitol by hydrogenating glucose, including the following steps:

[0093] Ruthenium trichloride is dissolved in a mixed solvent of methanol and water (volume ratio of 9:1) with a ruthenium content of 0.1wt%, stirred, and ultrasonically dispersed for 1 hour to obtain a ruthenium trichloride solution; the ruthenium trichloride solution is sprayed onto an activated carbon carrier by an ultrasonic spraying device at a speed of 80 revolutions per minute, a heating temperature of 50°C, and a spraying speed of 12mL / h to obtain a precursor, in which the ruthenium loading is 1wt%, the activated carbon particle size is 500μm, and the thickness of the ruthenium-containing active layer is 110μm; the precursor particles are reduced in a hydrogen atmosphere for 2 hours at a reduction temperature of 350°C to obtain a core-shell ruthenium carbon catalyst for subsequent glucose hydrogenation reaction.

[0094] A glucose solution with a mass concentration of 20 wt% was prepared, and the glucose solution was pumped into a micro-packed bed reactor, and fully mixed with hydrogen in a T-type micro-mixer at the inlet, and the molar ratio of hydrogen to glucose was controlled to be 2:1. The formed gas-liquid mixture passed through a catalytic bed filled with the core-shell type ruthenium carbon catalyst, the reaction temperature was controlled at 100°C, the reaction pressure was 1 MPa, the residence time of the reactants was 240 s, and the reaction product was separated by a gas-liquid separation tank to obtain a liquid product. The obtained liquid product was analyzed by high performance liquid chromatography, and the conversion rate of glucose was 100%, the yield of sorbitol was 99.6%, and the space-time yield was 1.34 g. polyol / (g cat h).

[0095] Stability test: The reaction was continued for 500 h under the above conditions. The reaction product was separated into liquid product by gas-liquid separation tank. Samples were taken regularly and analyzed by high performance liquid chromatography. The results are shown in Table 1.

[0096] Table 1

[0097] Reaction time (h) Glucose conversion rate (%) Sorbitol yield (%) 2 100 98.7 100 100 98.5 200 99.1 97.7 300 99.9 98.6 400 100 98.3 500 100 97.1

[0098] From the data in Table 1, it can be seen that the method for preparing sugar alcohols by catalytic hydrogenation of reducing sugars provided by the present invention has excellent stability, and still has good raw material conversion rate and target product yield after a long reaction. The ruthenium loading of the core-shell ruthenium carbon catalyst prepared in Example 1 before and after the reaction was analyzed using an inductively coupled plasma emission spectrometer, and the results showed that the ruthenium loading in the catalyst before the reaction was 1wt%, and the ruthenium loading in the catalyst after the reaction was 0.98wt%, indicating that there was no obvious metal loss in the core-shell ruthenium carbon catalyst provided by the present invention, and it has excellent stability.

[0099] Example 2

[0100] This embodiment provides a method for preparing sorbitol and mannitol by hydrogenating fructose, comprising the following steps:

[0101] Dissolve ruthenium(III) chloride in a mixed solvent of methanol and water (volume ratio 9:1) with a ruthenium content of 0.5 wt%, stir, and ultrasonically disperse for 1 hour to obtain a ruthenium(III) chloride solution; spray the above ruthenium(III) chloride solution onto an activated carbon support through an ultrasonic spraying device at a rotation speed of 80 revolutions per minute, a heating temperature of 50 °C, and a spraying speed of 12 mL / h to obtain a precursor, where the ruthenium loading is 1 wt%, the activated carbon particle size is 500 μm, and the ruthenium-containing active layer thickness is 30 μm; reduce the precursor particles in a hydrogen atmosphere for 2 hours at a reduction temperature of 350 °C to obtain a core-shell ruthenium-carbon catalyst for subsequent fructose hydrogenation reaction.

[0102] Prepare a fructose solution with a mass concentration of 20 wt%, pump the fructose solution into a micro-packed bed reactor, and mix it thoroughly with hydrogen in a T-shaped micro-mixer at the inlet, control the molar ratio of hydrogen to fructose to be 2:1. The formed gas-liquid mixture passes through a catalytic bed layer filled with the core-shell ruthenium-carbon catalyst, the reaction temperature is controlled at 100 °C, the reaction pressure is 1 MPa, the residence time of the reactants is 180 s, the reaction products are separated by a gas-liquid separation tank to obtain a liquid product. The obtained liquid product is analyzed by high-performance liquid chromatography. The conversion rate of fructose is 100%, the sorbitol yield is 49.6%, the mannitol yield is 50.4%, and the space-time yield is 1.80 g polyol / (g cat h).

[0103] Example 3

[0104] This example provides a method for hydrogenating mannose to prepare mannitol, which includes the following steps:

[0105] Dissolve ruthenium(III) chloride in a mixed solvent of methanol and water (volume ratio 9:1) with a ruthenium content of 0.1 wt%, stir, and ultrasonically disperse for 1 hour to obtain a ruthenium(III) chloride solution; spray the above ruthenium(III) chloride solution onto an activated carbon support through an ultrasonic spraying device at a rotation speed of 80 revolutions per minute, a heating temperature of 70 °C, and a spraying speed of 12 mL / h to obtain a precursor, where the ruthenium loading is 1 wt%, the activated carbon particle size is 500 μm, and the ruthenium-containing active layer thickness is 40 μm; reduce the precursor particles in a hydrogen atmosphere for 2 hours at a reduction temperature of 350 °C to obtain a core-shell ruthenium-carbon catalyst for subsequent mannose hydrogenation reaction.

[0106] Prepare a mannitol solution with a mass concentration of 20 wt%, pump the mannitol solution into a micro-packed bed reactor, and mix it thoroughly with hydrogen in a T-shaped micro-mixer at the inlet. Control the molar ratio of hydrogen to mannitol to be 2:1. The formed gas-liquid mixture passes through the catalytic bed filled with the core-shell ruthenium-carbon catalyst. The reaction temperature is controlled at 100 °C, the reaction pressure is 1 MPa, the residence time of the reactants is 180 s, and the reaction products are separated by a gas-liquid separation tank to obtain a liquid product. The obtained liquid product is analyzed by high-performance liquid chromatography. The conversion rate of mannitol is 100%, the yield of mannitol is 92.2%, and the space-time yield is 1.66 g polyol / (g cat h).

[0107] Example 4

[0108] This example provides a method for preparing xylitol by hydrogenating xylose, which includes the following steps:

[0109] Dissolve ruthenium trichloride in a mixed solvent of methanol and water (volume ratio 9:1), with a ruthenium content of 0.5 wt%. Stir and ultrasonically disperse for 1 hour to obtain a ruthenium trichloride solution; spray the above ruthenium trichloride solution onto an activated carbon support through an ultrasonic spraying device at a rotation speed of 80 revolutions per minute, a heating temperature of 50 °C, and a spraying speed of 12 mL / h to obtain a precursor, where the ruthenium loading is 1 wt%, the activated carbon particle size is 500 μm, and the ruthenium-containing active layer thickness is 30 μm; reduce the precursor particles in a hydrogen atmosphere for 2 hours at a reduction temperature of 350 °C to obtain a core-shell ruthenium-carbon catalyst for subsequent xylose hydrogenation reaction.

[0110] Prepare a xylose solution with a mass concentration of 20 wt%, pump the xylose solution into a micro-packed bed reactor, and mix it thoroughly with hydrogen in a T-shaped micro-mixer at the inlet. Control the molar ratio of hydrogen to xylose to be 1.5:1. The formed gas-liquid mixture passes through the catalytic bed filled with the core-shell ruthenium-carbon catalyst. The reaction temperature is controlled at 100 °C, the reaction pressure is 1 MPa, the residence time of the reactants is 120 s, and the reaction products are separated by a gas-liquid separation tank to obtain a liquid product. The obtained liquid product is analyzed by high-performance liquid chromatography. The conversion rate of xylose is 100%, the yield of xylitol is 97.6%, and the space-time yield is 2.64 g polyol / (g cat h).

[0111] Example 5

[0112] This example provides a method for preparing sorbitol by hydrogenating glucose, which includes the following steps:

[0113] In this example, the preparation process of the core-shell ruthenium-carbon catalyst is the same as that in Example 1.

[0114] Prepare a glucose solution with a mass concentration of 50 wt%, pump the glucose solution into a micro-packed bed reactor, and mix it thoroughly with hydrogen in a T-shaped micro-mixer at the inlet. Control the molar ratio of hydrogen to glucose to be 2:1. The formed gas-liquid mixture passes through the catalytic bed filled with the core-shell ruthenium-carbon catalyst. The reaction temperature is controlled at 120 °C, the reaction pressure is 3 MPa, the residence time of the reactants is 90 s, and the reaction products are separated by a gas-liquid separation tank to obtain liquid products. The obtained liquid products are analyzed by high-performance liquid chromatography. The conversion rate of glucose is 100%, the yield of sorbitol is 98.6%, and the space-time yield is 10.18 g polyol / (g cat h).

[0115] Comparative Example 1

[0116] The difference between this comparative example and Example 1 is only that: the active component used in the core-shell catalyst is nickel.

[0117] In this comparative example, the conversion rate of glucose is 13.5%, the yield of sorbitol is 11.9%, and the space-time yield is 0.16 g polyol / (g cat h).

[0118] Comparative Example 2

[0119] The difference between this comparative example and Example 1 is only that: the ruthenium content in the core-shell catalyst is 4 wt%.

[0120] In this comparative example, the conversion rate of glucose is 87.9%, the yield of sorbitol is 86.8%, and the space-time yield is 1.17 g polyol / (g cat h).

[0121] Comparative Example 3

[0122] This comparative example provides a method for preparing sorbitol by hydrogenating glucose, including the following steps:

[0123] The preparation process of the core-shell ruthenium-carbon catalyst in this comparative example is the same as that in Example 1.

[0124] Prepare a glucose solution with a mass concentration of 20 wt%, add the glucose solution and the core-shell ruthenium-carbon catalyst into a reaction kettle, stir evenly, seal the reactor, and replace it with hydrogen 3 times. Then introduce hydrogen and control the hydrogen pressure to be 1 MPa, the stirring speed to be 600 rpm, the reaction temperature to be 100 °C, keep the temperature for reaction for 4 h. After the reaction is completed, cool to room temperature and collect the liquid product. The obtained liquid product is analyzed by high-performance liquid chromatography. The conversion rate of glucose is 61.5%, the yield of sorbitol is 59.3%, and the space-time yield is 0.60 g polyol / (g cat h).

[0125] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc., mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0126] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A core-shell ruthenium-carbon catalyst, characterized in that: The core-shell ruthenium carbon catalyst comprises a carrier and an active component coated on the periphery of the carrier; The active component includes ruthenium; The support comprises a porous carbon material; The porous carbon material includes at least one of activated carbon, carbon black, nitrogen-containing carbon, or biochar; The content of the active component in the core-shell ruthenium-carbon catalyst is 0.5 wt % to 3 wt %.

2. The core-shell ruthenium-carbon catalyst according to claim 1, characterized in that The particle size of the carrier is 50 μm to 1000 μm; Optionally, the shell layer formed by the active component has a thickness of 20 μm to 200 μm.

3. A method for preparing the core-shell ruthenium-carbon catalyst according to claim 1 or 2, characterized in that: The following steps are involved: spraying a ruthenium salt solution onto a porous carbon material to obtain a precursor; The precursor is reduced in a hydrogen atmosphere to obtain the core-shell type ruthenium carbon catalyst.

4. The preparation method according to claim 3, characterized in that: The ruthenium content in the ruthenium salt solution is 0.01wt% to 5wt%; Optionally, the spraying speed is 6 mL / h to 30 mL / h; Optionally, the preparation method further comprises: heating the porous carbon material, spraying the ruthenium salt solution onto the porous carbon material to obtain a precursor; Optionally, the heating temperature is 50°C to 120°C.

5. The preparation method according to claim 3, characterized in that: The reduction temperature is 200°C to 400°C; Optionally, the reduction time is 1 h to 4 h.

6. Use of the core-shell ruthenium carbon catalyst according to claim 1 or 2 or the core-shell ruthenium carbon catalyst obtained by the preparation method according to any one of claims 3 to 5 in the preparation of sugar alcohols by hydrogenation of reducing sugars.

7. A method for preparing sugar alcohols by catalytic hydrogenation of reducing sugars, characterized in that: The following steps are involved: Adding a reducing sugar solution and hydrogen into a micro-packed bed reactor for continuous hydrogenation reduction treatment to obtain sugar alcohols; Wherein, the micro-packed bed reactor is filled with the core-shell type ruthenium carbon catalyst according to claim 1 or 2 or the core-shell type ruthenium carbon catalyst obtained according to the preparation method according to any one of claims 3-5.

8. The method according to claim 7, characterized in that The reducing sugar content in the reducing sugar solution is 10wt% to 50wt%; Optionally, the reducing sugar comprises an aldose and / or a ketose; Optionally, the reducing sugar includes at least one of glucose, mannose, xylose and fructose.

9. The method according to claim 7, characterized in that: The molar ratio of the reducing sugar to the hydrogen is 1:(1-3); Optionally, the reaction pressure of the continuous hydrogenation reduction treatment is 0.5 MPa to 3.5 MPa; Optionally, the reaction temperature of the continuous hydrogenation reduction treatment is 60°C to 120°C; Optionally, the reaction time of the continuous hydrogenation reduction treatment is 30s to 300s.

10. The method according to claim 7, characterized in that The sugar alcohol includes at least one of sorbitol, mannitol and xylitol.