Heterogeneous catalysts with dual catalytic centers, methods for their preparation and use - Patent Application 20070122997

Abstract

The present invention relates to the technical field of catalytic chemistry, particularly to a catalyst with a dual catalytic center, its preparation method and use, and a method for producing glycol. The catalyst comprises a porous support and, supported on the porous support, CN, a hydrogenation metal, and an inverse aldol catalyst metal, where the hydrogenation metal and the inverse aldol catalyst metal form clusters with CN. The hydrogenation metal and the inverse aldol catalyst metal are coordinated to the N-sites and supported on the porous support, forming clusters with CN, effectively stabilizing the metal active sites. The catalyst is used to produce glycol from polyhydroxy compounds. Both the raw material conversion and the selectivity for the glycol product are very high. The catalyst has high cycle stability, with no deactivation observed even after four cycles.

Description

Detailed Description of the Invention

[0001] [Technical field] The present invention relates to heterogeneous catalysts having dual catalytic centers, and to methods for their preparation and use, particularly in the production of glycols.

[0002] [Background technology] Glycols are common and abundant chemicals, and ethylene glycol, in particular, is an important basic chemical raw material for the production of polyester raw materials (e.g., PET, PEF), antifreeze, and refrigerants. Currently, the traditional industrial production route for ethylene glycol mainly relies on petroleum or natural gas as raw materials. This route has drawbacks, such as fossil fuel dependence, high energy consumption, and large amounts of carbon dioxide emissions. However, these drawbacks can be avoided by using sugar-based biomass as a starting material. Although sugar-based biomass is widely present in nature and is abundant and easily accessible, the technology for catalytically converting sugar-based biomass to ethylene glycol is currently immature. Therefore, the development of new catalysts and new conversion processes could facilitate the industrialization of this technology, thereby generating significant environmental and economic benefits.

[0003] CN105523890A discloses a method for producing glycol from sugar, using glucose directly as a raw material. The glucose is subjected to hydrolysis and hydrogenation in the presence of tungstate and a hydrogenation alloy catalyst to produce glycol. This method requires an alloy as a co-catalyst, resulting in high metal consumption. Furthermore, tungstate must be added to the reaction system as a co-catalyst, which is lost along with the solvent. CN102190562A, CN101735014A, and CN102731258A use WC2 and Ni nanoparticles as the primary catalytic active components to convert glucose to ethylene glycol, achieving a maximum glycol yield of 60%. CN103420796A uses a composite catalyst composed of the precious metal Ru / C and tungstic acid, achieving an ethylene glycol yield of 52-57%.

[0004] In other words, existing technologies mainly suffer from problems such as low glycol product yields and poor catalytic cycle stability, which pose major challenges for practical industrial application.

[0005] [Summary of the Invention] The object of the present invention is to overcome the problem of poor cycling stability of prior art sugar-based glycol catalysts by providing a heterogeneous catalyst with dual catalytic centers, which can be used to produce glycol from polyhydroxy compounds and has the advantages of low active component loss rate and excellent cycling stability.

[0006] To achieve the above object, the present invention provides a heterogeneous catalyst having a dual catalytic center, comprising a porous support and, supported on the porous support, a heterogeneously distributed ligand, a heterogeneously distributed hydrogenation metal, and a heterogeneously distributed retro-aldol catalyst metal, wherein the hydrogenation metal and the retro-aldol catalyst metal form clusters with the ligand, and the hydrogenation metal and the retro-aldol catalyst metal coordinate with a coordinating element of the ligand to form aggregates with the ligand having an average particle size of 5 to 100 nm.

[0007] A typical example of a ligand according to the present invention is C3N4.

[0008] For example, the heterogeneous catalyst having a dual catalytic center provided by the present invention is a dual catalytic center catalyst, which includes a porous support and, supported on the porous support, CN, a hydrogenation metal, and an anti-aldol catalyst metal, wherein the hydrogenation metal and the anti-aldol catalyst metal form clusters with CN.

[0009] The present invention also provides a method for preparing the catalyst according to the invention, characterized in that it comprises the following steps: (1) a step of dissolving a metal source for an anti-aldol catalyst, a metal hydrogenation source, and a ligand precursor in a solvent, and then contacting the resulting solution with a porous support to support the resulting solution on the porous support; (2) A step of calcining the product obtained in step (1) under an inert gas atmosphere.

[0010] For example, a method for preparing a catalyst provided by the present invention includes: (1) dissolving a metal source of an anti-aldol catalyst, a metal source of hydrogenation, and a C3N4 precursor in a solvent, and supporting the metal source of an anti-aldol catalyst, the metal source of hydrogenation, and the C3N4 precursor on a porous support; (2) A step of calcining the product obtained in step (1) under an inert gas atmosphere.

[0011] The present invention also provides the use of a heterogeneous catalyst having a dual catalytic center according to the present invention in the production of glycols from polyhydroxy compounds.

[0012] The present invention also provides a process for producing glycols, comprising hydrolyzing and hydrogenating polyhydroxy compounds in the presence of a heterogeneous catalyst having a dual catalytic center according to the present invention and hydrogen to produce glycols, the catalyst comprising the catalyst according to the present invention.

[0013] According to the prior art, the porous structure of activated carbon is beneficial for the diffusion of biomass polymers, but does not contribute to preventing the loss of metal active sites. In the heterogeneous catalyst with dual catalytic centers of the present invention, the hydrogenation metal and the retro-aldol catalyst metal are coordinated to the coordination sites (e.g., N sites) of the ligands and supported on the porous support so that they are distributed non-uniformly. The hydrogenation metal and the retro-aldol catalyst metal then form clusters with the ligands (e.g., CN), effectively stabilizing the metal active sites.

[0014] In the method for preparing a heterogeneous catalyst having a dual catalytic center according to the present invention, a metal source for the inverse aldol catalyst, a hydrogenation metal source, and a ligand (e.g., CN) precursor are dissolved in a solvent and pre-coordinated, and then supported on a porous support. As a result, the hydrogenation metal and the metal for the inverse aldol catalyst are coordinated to the coordination sites (e.g., N sites) of the ligand and supported on the porous support, forming clusters with the ligand (e.g., CN).

[0015] When the heterogeneous catalyst having a dual catalytic center according to the present invention is used to produce glycols from polyhydroxy compounds, both the conversion rate of the raw material and the selectivity to the product glycol are significantly high. Furthermore, when the hydrogenation metal and the retro-aldol catalyst metal form clusters with ligands (e.g., CN), the coordination effect between the metal and the coordination site (e.g., N site) of the ligand significantly reduces the loss of the hydrogenation metal and the retro-aldol catalyst metal during the reaction, effectively stabilizing the metal active site and improving the cycle stability of the catalyst. No catalyst deactivation is observed even after four cycles of use.

[0016] [Brief description of the drawing] FIG. 1 is a scanning electron microscope (SEM) image of the NiW-C3N4 / AC catalyst of Example 1; FIG. 2 is an X-ray photoelectron spectroscopy (XPS) spectrum of Ni element contained in the catalyst obtained in Example 1; FIG. 3 is an X-ray photoelectron spectroscopy (XPS) spectrum of W element contained in the catalyst obtained in Example 1; Figure 4 is the XRD pattern of the catalyst obtained in Example 1; FIG. 5 shows a transmission electron microscope HAADF image, an EDS image, and a particle size distribution diagram of the catalyst obtained in Example 1.

[0017] FIG. 6 is a statistical diagram of the average particle size of the catalyst clusters obtained in Example 1.

[0018] [Detailed Description of the Invention] The range endpoints and any values ​​disclosed herein should be understood not to be limited to the exact range or value, but to include values ​​close to these ranges or values. For numerical ranges, two of the range endpoints, one of the range endpoints, and one of the individual point values, and two of the individual point values ​​can be combined with each other to obtain one or more new numerical ranges. These numerical ranges should be considered to be specifically disclosed herein.

[0019] The present invention provides a heterogeneous catalyst having a dual catalytic center. The catalyst includes a porous support and, supported on the porous support, a non-uniformly distributed ligand, a non-uniformly distributed hydrogenation metal, and a non-uniformly distributed retro-aldol catalyst metal. The hydrogenation metal and the retro-aldol catalyst metal form clusters with the ligand, and the hydrogenation metal and the retro-aldol catalyst metal coordinate with a coordination element of the ligand to form aggregates with the ligand having an average particle size in the range of 5 to 100 nm.

[0020] In the present invention, unless otherwise specified, all descriptions of amounts, contents, and related ratios are on a "by weight" basis unless clearly contradicted by common understanding in the art.

[0021] For purposes of the present invention, the term "dual catalytic center" refers to a catalyst in which there is a catalytic center that has both active functions, i.e., hydrogenation catalysis and retro-aldol catalysis are achieved by coordinating both the hydrogenation metal and retro-aldol catalyst metal to the coordination elements of a ligand and supporting both on the same porous support.

[0022] Those skilled in the art can confirm the coordination from, for example, the XPS spectrum of the catalyst as shown in FIG. 2 and FIG. 3, based on technical knowledge known in the art.

[0023] The term "cluster" has the general meaning known in the art, but for the purposes of the present invention, it refers to an aggregate having an average particle size of 5 to 100 nm formed from the hydrogenation metal and the retro-aldol catalyst metal and the ligand through coordination between the hydrogenation metal and the retro-aldol catalyst metal and the coordination element of the ligand. As an example, a transmission electron microscope HAADF image of a heterogeneous catalyst can be obtained, and based on this, the average particle size of the cluster can be statistically analyzed using Nano measurer particle size analysis software.

[0024] For purposes of the present invention, the terms hydrogenation reaction and retro-aldol reaction each have the meanings known in the art. For example, the aldol condensation reaction is generally known to be a reversible reaction, with the forward reaction involving the formation of a hydroxyaldehyde or hydroxyketone from an aldehyde or ketone containing an active hydrogen under the catalysis of a base or acid, and the reverse reaction involving the hydrolysis of the hydroxyaldehyde or hydroxyketone under the catalysis of a catalyst, i.e., retro-aldol reaction.

[0025] In the art, catalysts used in hydrogenation reactions are generally heterogeneous, while catalysts suitable for retro-aldol reactions are generally homogeneous. For example, see US20110312487, which reports the use of a homogeneous material containing tungsten as a retro-aldol catalyst. For purposes of the present invention, the terms "homogeneous" and "heterogeneous" have their respective meanings known in the art. A catalyst uniformly dispersed in a reaction medium in a dissolved or other form, such as a solution, can be considered an example of a homogeneous catalyst, while a catalyst supported on particles by coating or other means can be considered an example of a heterogeneous catalyst.

[0026] Through thorough research, the present inventors have unexpectedly found that, for the purpose of the present invention, a catalyst in which both the hydrogenation catalyst and the retro-aldol catalyst are provided in a heterogeneous form can be prepared by a simple process, particularly by simultaneously supporting the hydrogenation metal and the retro-aldol catalyst metal, thereby facilitating the hydrogenation metal and the retro-aldol catalyst metal to play the role of the dual catalytic center, thereby achieving desirable technical effects in terms of the conversion rate of reactants, the yield of products, etc.

[0027] According to the present invention, the ligand may be C3N4 or a derivative thereof, including carbon nitride doped with heteroatoms (preferably selected from phosphorus and sulfur), defective carbon nitride, carbon nitride heterojunctions or carbon nitride copolymers.

[0028] According to the present invention, the hydrogenation metal and the retroaldol catalyst metal each coordinate to a coordination element of the ligand. For example, if Ni is used as the hydrogenation metal and CN is used as the ligand, one Ni atom coordinates with at least one N atom of the CN lattice, thereby anchoring it to the CN lattice and forming a Ni-N active single site. Similarly, the retroaldol metal lacks electrons and has an empty orbital. On the other hand, the coordination site on the ligand (e.g., N) has a single pair of electrons that can bond with the empty orbital to form a coordination site.

[0029] According to the present invention, each atom of the hydrogenation metal and the retroaldol catalyst metal can essentially be coordinated with a ligand, for example, the molar ratio of uncoordinated metal atoms to the total amount of metal atoms is 10% or less, preferably 5% or less, more preferably 2% or less.

[0030] To achieve coordination of all atoms of the hydrogenation metal and the retro-aldol catalyst metal, the molar amount of the coordination element in the present invention is preferably equal to or greater than the molar amount of the metal atoms. For example, according to the present invention, the molar ratio of the coordination element to the metal atoms is 2:1 or greater, preferably 4:1 or greater, and more preferably 8:1 or greater.

[0031] According to a preferred embodiment of the present invention, the clusters have an average particle size in the range of 5 to 100 nm, more preferably 5 to 30 nm.

[0032] According to a preferred embodiment of the present invention, the hydrogenation metal and the retro-aldol catalyst metal are supported on the support in the form of an active single site of the metal.

[0033] According to a preferred embodiment of the present invention, the porous carrier has an average particle size in the range of 0.01 to 1 mm, preferably 0.1 to 0.5 mm.

[0034] According to a preferred embodiment of the present invention, the porous carrier has a particle size of 200 to 2000 m 2 ·g -1 It has a specific surface area in the range of

[0035] In the present invention, the weight content of the hydrogenation metal in the catalyst can be selected within a wide range. According to a preferred embodiment of the present invention, the content of the hydrogenation metal is in the range of 1% to 50%, preferably 6% to 30%, based on the total weight of the catalyst.

[0036] In the present invention, the weight content of the retro-aldol catalyst metal in the catalyst can be selected from a wide range. According to a preferred embodiment of the present invention, the content of the retro-aldol catalyst metal is in the range of 0.1% to 50%, preferably 10% to 30%, based on the total weight of the catalyst.

[0037] For purposes of the present invention, the content of each metal in the catalyst can be calculated as follows: Catalyst metal weight content % = (weight content of metal in raw material) / (weight of prepared catalyst) x 100%.

[0038] In the present invention, the weight content of the porous support in the catalyst can be selected within a wide range. According to a preferred embodiment of the present invention, the content of the porous support is in the range of 25 to 96.9%, preferably 40 to 84%, based on the total weight of the catalyst.

[0039] In the present invention, the weight content of the ligand (e.g., CN) in the catalyst can be selected within a wide range. According to a preferred embodiment of the present invention, the content of the ligand (e.g., CN) is in the range of 2 to 50%, preferably 10 to 30%, based on the total weight of the catalyst.

[0040] According to a preferred embodiment of the present invention, the weight ratio of the retro-aldol catalyst metal to the hydrogenation metal is in the range of 0.5 to 6, preferably 0.8 to 2.5.

[0041] According to the present invention, the porous carrier has a wide range of selectable types. Any conventional porous carrier in the art can be used in the present invention. According to a preferred embodiment of the present invention, the porous carrier is selected from carbon-based porous carriers, preferably selected from at least one of graphene, graphene, activated carbon fiber, activated carbon, and carbon nanotubes, and more preferably activated carbon.

[0042] According to the present invention, the type of the metal hydride is not particularly limited, and any conventional metal hydride in the art can be used in the present invention. According to a preferred embodiment of the present invention, the metal hydride is selected from at least one of Ni, Fe, Cu, Pt, Pd, Ru, and Rh, and preferably selected from at least one of Ni, Fe, and Cu.

[0043] According to the present invention, the type of the retro-aldol catalyst metal is not particularly limited, and any conventional retro-aldol catalyst metal in the art can be used in the present invention. According to a preferred embodiment of the present invention, the retro-aldol catalyst metal is selected from at least one of W, Mo, and Ce.

[0044] In the present invention, there is no specific requirement for the preparation method of the catalyst. The present invention provides a preparation method of the catalyst according to the present invention as an example, which includes the following steps: (1) dissolving a metal source for the retro-aldol catalyst, a metal hydrogenation source, and a ligand (e.g., CN) precursor in a solvent, and then contacting the solution with a porous support to support the precursor on the porous support; (2) A step of calcining the product obtained in step (1) under an inert gas atmosphere.

[0045] In the present invention, a metal source for the inverse aldol catalyst, a metal source for hydrogenation, and a ligand (e.g., CN) precursor are dissolved in a solvent and pre-coordinated, and then supported on a porous support. As a result, the hydrogenation metal and the metal for the inverse aldol catalyst are coordinated to the coordination sites (e.g., N sites) and supported on the porous support, forming clusters with the ligand (e.g., CN).

[0046] According to a preferred embodiment of the present invention, step (1) comprises: i) dissolving a retro-aldol catalyst metal source and a ligand (e.g., CN) precursor in a first solvent to obtain a first solution, and dissolving a hydrogenation metal source and a ligand (e.g., CN) precursor in a second solvent to obtain a second solution; ii) impregnating the porous carrier with the first solution and the second solution, respectively, and then drying the carrier;

[0047] According to a preferred embodiment of the present invention, the impregnation process is carried out by equal volume impregnation (single or multiple times). According to the preparation method of the present invention, the catalyst obtained using simple impregnation does not need to be reduced with hydrogen and can be used as a catalyst by directly calcining. The method of the present invention is simple, relies on inexpensive raw materials, and is suitable for large-scale industrial production.

[0048] According to a preferred embodiment of the present invention, the impregnation process is carried out by multiple equal volume impregnations, each of which is followed by drying, and the number of impregnations is adjusted according to the concentration of the impregnation solution and the object to be impregnated.

[0049] According to a preferred embodiment of the present invention, the drying conditions include a temperature of 50 to 120° C. and a time of 5 to 15 hours.

[0050] There is no special requirement for the number of times of impregnation, and the number of times of impregnation can be determined according to actual needs.

[0051] In the present invention, the metal source for the retroaldol catalyst, the metal hydrogenation source, and the ligand (e.g., CN) precursor are dissolved in a solvent for pre-coordination. The dissolution rate can be accelerated by ultrasonication, stirring, etc.

[0052] In the present invention, there is no particular limitation on the firing conditions, and any conventional firing method in the art can be used in the present invention. According to a preferred embodiment of the present invention, the firing conditions include a firing temperature of 300 to 600°C and a firing time of 0.5 to 12 hours.

[0053] In the present invention, the weight ratio of the metal hydride source to the ligand (e.g., CN) precursor can be selected within a wide range. According to a preferred embodiment of the present invention, the weight ratio of the metal hydride source to the ligand (e.g., CN) precursor is in the range of (0.5-10):1, preferably (1-3):1.

[0054] In the present invention, the weight ratio of the metal source of the retroaldol catalyst to the ligand (e.g., CN) precursor can be selected within a wide range. According to a preferred embodiment of the present invention, the weight ratio of the metal source of the retroaldol catalyst to the ligand (e.g., CN) precursor is in the range of (0.5 to 10):1, preferably (1 to 3):1.

[0055] According to a preferred embodiment of the present invention, the product obtained in step (1) is pretreated before calcination. The pretreatment conditions include treatment under an inert gas or air atmosphere at 30 to 100°C for 0.25 to 24 hours, preferably at 35 to 90°C for 0.5 to 18 hours, and more preferably at 50 to 85°C for 6 to 12 hours.

[0056] In the present invention, the type of ligand (e.g., CN) precursor is not particularly limited, and any conventional ligand (e.g., CN) precursor in the art can be used in the present invention. According to a preferred embodiment of the present invention, the ligand (e.g., CN) precursor is selected from at least one of urea, dicyandiamide, melamine, and guanidine hydrochloride, and preferably selected from at least two of urea, dicyandiamide, melamine, and guanidine hydrochloride.

[0057] According to a preferred embodiment of the present invention, the ligand (e.g., CN) precursor is selected from a mixture of melamine and guanidine hydrochloride, more preferably the weight ratio of melamine to guanidine hydrochloride is in the range of 0.5 to 2:1, for example, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1.

[0058] In the present invention, the type of metal hydride source is not particularly limited, and any conventional metal hydride source in the art can be used in the present invention. According to a preferred embodiment of the present invention, the metal hydride source is selected from soluble salts of metal hydrides, preferably selected from metal hydride acetates, metal hydride nitrates, metal hydride chlorides, and metal hydride sulfates.

[0059] According to a preferred embodiment of the present invention, the metal hydride source is at least one of nickel acetate, nickel nitrate, nickel chloride, and nickel sulfate.

[0060] In the present invention, the type of the inverse aldol catalyst metal source is not particularly limited, and any conventional inverse aldol catalyst metal source in the art can be used in the present invention. According to a preferred embodiment of the present invention, the inverse aldol catalyst metal source is selected from at least one of a soluble salt of an inverse aldol catalyst metal, a soluble acid of an inverse aldol catalyst metal, and a soluble oxide of an inverse aldol catalyst metal.

[0061] It should be understood that in the present invention, "soluble" means soluble in the respective corresponding solvent.

[0062] According to a preferred embodiment of the present invention, the retroaldol catalyst metal source is selected from at least one of tungstic acid, ammonium metatungstate, and tungsten oxide.

[0063] In the present invention, the type of various solvents is not particularly limited, and any conventional solvent in the art can be used in the present invention. For example, the solvent according to the present invention can be independently selected from at least one of water, methanol, ethanol, and ethyl acetate, and is preferably water and / or methanol.

[0064] According to a preferred embodiment of the present invention, the first solvent is methanol and the second solvent is water.

[0065] The present invention also provides use of the catalyst of the present invention in the production of glycol from polyhydroxy compounds. The catalyst of the present invention is particularly suitable for the production of glycol from polyhydroxy compounds, where the polyhydroxy compound is selected from at least one of starch, hemicellulose, sucrose, glucose, fructose, furfural, and fructan. When the catalyst of the present invention is used in the production of glycol from polyhydroxy compounds, both the conversion rate of the raw material and the selectivity for the glycol product are very high, and the catalyst has high cycle stability.

[0066] The present invention also provides a method for producing glycols, which comprises hydrolyzing and hydrogenating polyhydroxy compounds in the presence of the catalyst according to the present invention and hydrogen to produce glycols.

[0067] According to a preferred embodiment of the present invention, the weight ratio of polyhydroxy compound to the catalyst according to the present invention is in the range of 10 to 0.1, preferably 5 to 0.5.

[0068] According to a preferred embodiment of the present invention, the weight ratio of water to polyhydroxy compound is in the range of 30-300:1.

[0069] According to a preferred embodiment of the present invention, the initial hydrogen charging pressure is in the range of 0.5 to 10 MPa, preferably 1 to 6 MPa.

[0070] According to a preferred embodiment of the present invention, the conditions for hydrolysis and hydrogenation include a reaction temperature of 150 to 300° C., preferably 200 to 245° C., and a reaction time of 0.5 to 12 hours, preferably 0.5 to 4 hours.

[0071] [Example] In order to facilitate understanding of the present invention, the present invention provides the following examples. However, these examples are only used to facilitate understanding of the present invention, and should not be considered as particularly limiting the present invention.

[0072] In this study, the reaction products (e.g., ethylene glycol, propylene glycol, butylene glycol) were qualitatively analyzed by gas chromatography-mass spectrometry (GC-MS), and the yield of the glycol products (e.g., ethylene glycol, propylene glycol, butylene glycol) and the conversion of the raw material glucose were analyzed by gas chromatography (GC). The gas chromatography-mass spectrometer used was an Agilent 7890A (Agilent, USA), the chromatography column was an HP-5 nonpolar capillary column (30 m, 0.53 mm), the gas chromatograph was an Agilent 7890B, the detector was a flame ionization detector (FID), and the chromatography column was an SE-54 capillary column (30 m, 0.53 mm).

[0073] In the present invention, the valence state of the metal supported on the catalyst was characterized by X-ray photoelectron spectroscopy.

[0074] In the present invention, the single-site state of the metal was characterized by spherical aberration corrected electron microscopy.

[0075] In the present invention, the amount of metal lost after the reaction was characterized by inductively coupled plasma optical emission spectroscopy (ICP).

[0076] The catalyst metal loss rate was calculated as follows: Catalyst metal loss % = (metal content in solution after reaction) / (metal content in catalyst at the start of reaction) x 100%.

[0077] The glucose conversion was calculated as follows: Glucose conversion rate % = (molar amount of glucose involved in the reaction) / (molar amount of glucose as raw material at the start of the reaction) × 100%.

[0078] The yields of the glycol products (ethylene glycol, propylene glycol, butylene glycol) were calculated as follows: Yield (%) of the glycol product = (number of carbon atoms equivalent to the molar amount of glycol produced by the reaction) / (number of carbon atoms equivalent to the molar amount of glucose used as the starting material at the start of the reaction) × 100%.

[0079] Selectivity (%) of the glycol product = (number of carbon atoms equivalent to the moles of glycol produced by the reaction) / (molar amount of glucose involved in the reaction) × 100%.

[0080] The average particle size of the clusters was measured as follows: Based on the HAADF images obtained by an electron microscope, the average particle size of the clusters was statistically analyzed using Nano measurer particle size analysis software.

[0081] In the example below, the average particle size of activated carbon is 0.25 to 1 mm, and the specific surface area is 1682 m 2 ·g -1 It was.

[0082] Example 1 (1) 0.102 g of ammonium metatungstate and 0.1 g of dicyandiamide were dissolved in 3 mL of deionized water under heating and sonicated for 30 minutes to prepare one part of solution A. 0.107 g of nickel acetate tetrahydrate and 0.1 g of dicyandiamide were dissolved in 3 mL of deionized water under heating and sonicated for 30 minutes to prepare one part of solution B. The impregnation process was carried out by multiple equal-volume impregnations. The impregnation steps were as follows: 1 part of solution A was added to 1 g of activated carbon (AC), the mixture was shaken until uniformly mixed, and the mixture was placed in a drying oven at 80°C for 10 hours. This impregnation step was repeated twice. 1 part of solution B was added to 1 g of activated carbon (AC), the mixture was shaken until uniformly mixed, and the mixture was placed in a drying oven at 80°C for 10 hours. This impregnation step was repeated six times. A total of 2 parts of solution A (impregnated twice with solution A) and 6 parts of solution B (impregnated six times with solution B) were added, and the resulting product was pretreated at 70° C. for 9 hours under a nitrogen atmosphere.

[0083] (2) The obtained sample was heated to 550°C in a nitrogen atmosphere and sintered for 2 hours to form Ni 15% W 15% -C3N4 / AC catalyst was obtained.

[0084] The SEM image of the catalyst is shown in Figure 1. The active sites are located within the pores of the activated carbon, and only a few can be observed on the surface; The XPS spectra of the catalyst are shown in Figures 2 and 3. Figures 2 and 3 show that Ni and W elements are supported on the activated carbon mainly in the form of ions coordinated to carbon nitride; The XRD pattern of the catalyst is shown in Figure 4. From Figure 4, it can be seen that Ni and W elements are not present in the form of nanoparticles on the support; A transmission electron microscope image of the catalyst is shown in Figure 5. Figure 5 shows that the distribution of W, Ni, and N sites on the activated carbon in the sample is consistent. Figure 6 shows a statistical diagram of the average particle size of the clusters on the catalyst. The average particle size of the NiW-CN clusters ranges from 11 to 23 nm. The catalyst composition and the average particle size range of the clusters are shown in Table 1.

[0085] Example 2 Example 2 was carried out in accordance with the method of Example 1, except that in step (1), the impregnation step was carried out as follows. 1 part of Solution A or Solution B was added to 1 g of activated carbon, and the mixture was shaken until uniformly mixed, and then placed in a drying oven at 80°C for 10 hours. This impregnation step was repeated six times, with a total of 2 parts of Solution A and 4 parts of Solution B being added. The remaining conditions were the same as in Example 1, and Ni 10% W 15% The catalyst composition is shown in Table 1.

[0086] Example 3 Example 3 was carried out in accordance with the method of Example 2, except that in step (1), the solvent for dissolving ammonium metatungstate was changed to methanol. Specifically, 0.102 g of ammonium metatungstate and 0.1 g of dicyandiamide were dissolved in 3 mL of methanol under heating, and the solution was sonicated for 30 minutes to prepare solution A. 0.107 g of nickel acetate tetrahydrate and 0.1 g of dicyandiamide were dissolved in 3 mL of deionized water under heating, and the solution was sonicated for 30 minutes to prepare solution B. The remaining conditions were the same as in Example 2, and Ni 10% W 15% The catalyst composition is shown in Table 1.

[0087] Example 4 Example 4 was carried out in accordance with the method of Example 1, except that in step (1), the impregnation step was carried out as follows. 1 part of Solution A or Solution B was added to 1 g of activated carbon, and the mixture was shaken until uniformly mixed, and then placed in a drying oven at 80°C for 10 hours. This impregnation step was repeated twice, with a total of 0.33 parts of Solution A and 1 part of Solution B being added. The remaining conditions were the same as in Example 1, and Ni 2.5% W 2.5% The catalyst composition is shown in Table 1.

[0088] Example 5 Example 5 was carried out in accordance with the method of Example 1, except that methanol was used as the solvent in place of deionized water in step (1). The remaining conditions were the same as in Example 1, and Ni 15% W 15%The catalyst composition is shown in Table 1.

[0089] Example 6 Example 6 was carried out in accordance with the method of Example 1, except that ethanol was used as the solvent in place of deionized water in step (1). The remaining conditions were the same as in Example 1, and Ni 15% W 15% The catalyst composition is shown in Table 1.

[0090] Example 7 Example 7 was carried out in accordance with the method of Example 1, except that ethyl acetate was used as the solvent in place of deionized water in step (1). The remaining conditions were the same as in Example 1, and Ni 15% W 15% The catalyst composition is shown in Table 1.

[0091] Example 8 Example 8 was carried out according to the method of Example 1, except that in step (1), melamine and guanidine hydrochloride (weight ratio 1:1) were used instead of dicyandiamide, and solutions A and B were prepared without changing the total amount of the C3N4 source. The remaining conditions were the same as in Example 1. The catalyst composition is shown in Table 1.

[0092] Example 9 (1) 0.103 g of ammonium molybdate and 0.1 g of dicyandiamide were dissolved in 3 mL of deionized water under heating and sonicated for 30 minutes to prepare Solution A. 0.135 g of cupric chloride dihydrate and 0.1 g of dicyandiamide were dissolved in 3 mL of deionized water under heating and sonicated for 30 minutes to prepare Solution B. The impregnation process was carried out by multiple equal-volume impregnations. The impregnation steps were as follows: 1 part of Solution A or Solution B was added to 1 g of activated carbon (AC), shaken until uniformly mixed, and then placed in a drying oven at 80°C for 10 hours. This impregnation process was repeated six times, with a total of 2 parts of Solution A and 4 parts of Solution B added.

[0093] (2) The obtained sample was heated to 550°C in a nitrogen atmosphere and sintered for 2 hours to obtain Cu. 20% Mo 10% The catalyst composition is shown in Table 1.

[0094] Comparative Example 1 Solution A was prepared by dissolving 0.102 g of ammonium metatungstate in 3 mL of deionized water under heating and sonicating for 30 minutes. Solution B was prepared by dissolving 0.107 g of nickel acetate tetrahydrate in 3 mL of deionized water under heating and sonicating for 30 minutes. The impregnation process was carried out by multiple equal-volume impregnations. The standard procedure was as follows: 1 part of Solution A or Solution B was added to 1 g of activated carbon, shaken until uniformly mixed, and then placed in a drying oven at 80 °C for 10 hours. This procedure was repeated six times throughout the process, adding a total of 2 parts of Solution A and 6 parts of Solution B. The resulting sample was heated to 600 °C under a nitrogen atmosphere and calcined for 4 hours, followed by reduction at 450 °C under a hydrogen atmosphere for 2 hours to obtain Ni. 15% W 15% The catalyst composition is shown in Table 1.

[0095] Comparative Example 2 Ni 15% W 15% The / AC-C3N4 catalyst was prepared by the equal volume impregnation method. 0.102 g of ammonium metatungstate was dissolved in 3 mL of deionized water under heating and ultrasonicated for 30 minutes to prepare solution A. 0.107 g of nickel acetate was dissolved in 3 mL of deionized water under heating and ultrasonicated for 30 minutes to prepare solution B. The impregnation process was carried out by multiple equal volume impregnations. The standard procedure was as follows: 1 part of solution A or solution B was added to activated carbon loaded with C3N4 (where the amount of activated carbon was 1 g and the amount of C3N4 was 0.6 g), shaken until uniformly mixed, and then placed in a drying oven at 80 °C for 10 hours. This procedure was repeated 8 times throughout the entire process, with a total of 2 parts of solution A and 6 parts of solution B added. The resulting sample was heated to 600 °C under a nitrogen atmosphere and calcined for 4 hours, followed by reduction at 450 °C under a hydrogen atmosphere for 2 hours to obtain Ni. 15 W 15The catalyst composition is shown in Table 1.

[0096] Examples 10 to 18 The preparation reaction of ethylene glycol by catalytic conversion of glucose was carried out in a sealed autoclave. 0.075 g of the catalyst obtained in Examples 1 to 9 above, 0.25 g of glucose, and 25 mL of deionized water were added to an autoclave equipped with a stirrer. Hydrogen was introduced into the autoclave to purge the interior three times, after which the autoclave was sealed and pressurized with hydrogen to 4 MPa. The heating mantle was heated to 245°C, and magnetic stirring was initiated. The reaction was carried out at 245°C for 1 hour. The products in the reaction solution were quantitatively analyzed using gas chromatography, and the raw materials in the reaction solution were quantitatively analyzed using liquid chromatography. The glucose conversion rate and glycol yield were calculated according to the above formula (see Table 2). The glycol selectivity was calculated according to the above formula (see Table 3).

[0097] Comparative Examples 3 and 4 The difference between Comparative Examples 3 and 4 and Examples 10 to 18 is that the catalyst used in Comparative Example 3 was the Ni 15% W 15% The catalyst used in Comparative Example 4 was the Ni / AC catalyst prepared in Comparative Example 2. 15% W 15% / AC-C3N4 catalyst.

[0098] [Table 1]

[0099] [Table 2]

[0100] [Table 3]

[0101] Using ICP, the metal contents in the reaction solutions obtained in Examples 10 to 18 and Comparative Examples 3 and 4 were quantitatively analyzed. The results are shown in Table 4.

[0102] [Table 4]

[0103] As shown in Table 4, the catalyst with dual catalytic centers according to the present invention has the advantages of low loss rate of active components and excellent cycle stability.

[0104] Example 19 The catalyst prepared in Example 1 was washed and dried before being used in the next reaction. The following reaction was repeated four times in total. The results are shown in Table 5. 0.075 g of Ni prepared in Example 1 15% W 15% The -C3N4 / AC catalyst, 0.25 g of furfural, and 25 mL of deionized water were added to an autoclave equipped with a stirrer. Hydrogen was introduced to purge the autoclave three times, after which the autoclave was sealed and pressurized with hydrogen to 4 MPa. The heating mantle was heated to a preset temperature, and stirring was initiated using a magnetic stirrer. The reaction solution was subjected to gas-phase analysis. The reaction was carried out at 245°C for 1 hour. The products in the reaction solution were quantitatively analyzed using gas chromatography, and the raw materials in the reaction solution were quantitatively analyzed using liquid chromatography.

[0105] [Table 5]

[0106] As shown in Table 5, the catalyst with dual catalytic centers according to the present invention has high catalytic stability, with no deactivation of the catalyst observed after four cycles of use.

[0107] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited thereto. Within the scope of the technical idea of ​​the present invention, the technical solution of the present invention can accept various simple modifications, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the contents disclosed by the present invention and fall within the protection scope of the present invention. [Brief explanation of the drawings]

[0108] [Figure 1] 1 is a scanning electron microscope (SEM) image of the NiW-C 3 N 4 / AC catalyst of Example 1. [Figure 2] 1 is an X-ray photoelectron spectroscopy (XPS) spectrum of Ni element contained in the catalyst obtained in Example 1. [Figure 3] 1 is an X-ray photoelectron spectroscopy (XPS) spectrum of W element contained in the catalyst obtained in Example 1. [Figure 4] 1 is an XRD pattern of the catalyst obtained in Example 1. [Figure 5] 1A and 1B are a transmission electron microscope HAADF image, an EDS image, and a particle size distribution diagram of the catalyst obtained in Example 1. [Figure 6] FIG. 2 is a statistical diagram of the average particle size of the catalyst clusters obtained in Example 1.

Claims

1. A heterogeneous catalyst having a dual catalytic center, comprising: a porous support; and, supported on the porous support, a non-uniformly distributed ligand, a non-uniformly distributed hydrogenation metal, and a non-uniformly distributed retro-aldol catalyst metal, wherein the hydrogenation metal and the retro-aldol catalyst metal form clusters with the ligand, and the hydrogenation metal and the retro-aldol catalyst metal coordinate with a coordination element of the ligand to form aggregates with the ligand having an average particle size in the range of 5 to 100 nm.

2. The ligand is C ３ N ４ or a derivative thereof, ３ N ４ 2. The catalyst of claim 1, wherein the derivative comprises heteroatom-doped carbon nitride, defective carbon nitride, carbon nitride heterojunction, or carbon nitride copolymer, preferably wherein the heteroatom is selected from phosphorus and sulfur.

3. 3. The catalyst according to claim 1, wherein the clusters have an average particle size in the range of 5 to 30 nm.

4. Catalyst according to any one of the preceding claims, wherein the hydrogenation metal is supported on the porous support in the form of an active single metal site, and preferably the retro-aldol catalyst metal is also supported on the porous support in the form of an active single metal site.

5. the porous carrier has an average particle size in the range of 0.01 to 1 mm, preferably 0.1 to 0.5 mm; and / or The porous carrier has a thickness of 200 to 2000 m ２ ・g －１ Catalyst according to any one of the preceding claims, having a specific surface area in the range of

6. the content of the hydrogenation metals is in the range of 1% to 50%, preferably 6% to 30%, based on the total weight of the catalyst; and / or the content of the retro-aldol catalyst metal is in the range of 0.1% to 50%, preferably 10% to 30%, and / or The content of the porous carrier is in the range of 25 to 96.9%, preferably 40 to 84%, and / or the content of said ligands is in the range of 2 to 50%, preferably 10 to 30%, and / or Catalyst according to any one of the preceding claims, wherein the weight ratio of the retro-aldol catalyst metal to the hydrogenation metal is in the range of 0.5 to 6, preferably 0.8 to 2.

5.

7. The porous support is selected from carbon-based porous supports, preferably selected from at least one of graphene, graphene, activated carbon fiber, activated carbon, and carbon nanotubes; and / or the hydrogenation metal is selected from at least one of Ni, Fe, Cu, Pt, Pd, Ru and Rh; and / or Catalyst according to any one of the preceding claims, wherein the retro-aldol catalyst metal is selected from at least one of W, Mo and Ce.

8. A method for preparing a catalyst according to any one of the preceding claims, characterized in that it comprises the following steps: (1) dissolving a metal source for the retro-aldol catalyst, a metal hydrogenation source, and a ligand precursor in a solvent, and then contacting the resulting solution with a porous support to support the resulting solution on the porous support; (2) A step of calcining the product obtained in step (1) under an inert gas atmosphere.

9. 9. The method according to claim 8, wherein the solvent is selected from at least one of water, methanol, ethanol and ethyl acetate, preferably water and / or methanol.

10. The step (1) i) dissolving the retro-aldol catalyst metal source and the ligand precursor in a first solvent to obtain a first solution, and dissolving the hydrogenation metal source and the ligand precursor in a second solvent to obtain a second solution; ii) impregnating a porous carrier with the first solution and the second solution, and then drying the carrier; Preferably, the first solvent is methanol and the second solvent is water; and / or The impregnation is carried out by equal volume impregnation, and / or The method according to claim 8 or 9, wherein the firing conditions include a firing temperature of 300 to 600°C and a firing time of 0.5 to 12 hours.

11. the weight ratio of the metal hydrogenation source to the ligand precursor is in the range of (0.5-10):1, preferably (1-3):1; and / or The method according to any one of claims 8 to 10, wherein the weight ratio of the retro-aldol catalyst metal source to the ligand precursor is in the range of (0.5-10):1, preferably (1-3):

1.

12. The method according to any one of claims 8 to 11, wherein the product obtained in the step (1) is pretreated before the calcination in the step (2), and the pretreatment conditions include treating the product at 30 to 100°C for 0.25 to 24 hours in an inert gas or air atmosphere.

13. the ligand precursor is selected from at least one of urea, dicyandiamide, melamine and guanidine hydrochloride; and / or the metal hydride source is selected from soluble salts of metal hydrides, preferably at least one of metal hydride acetates, metal hydride nitrates, metal hydride chlorides and metal hydride sulfates, preferably at least one of nickel acetate, nickel nitrate, nickel chloride and nickel sulfate; and / or the source of the retro aldol catalyst metal is selected from at least one of a soluble salt of the retro aldol catalyst metal, a soluble acid of the retro aldol catalyst metal, and a soluble oxide of the retro aldol catalyst metal, preferably at least one of tungstic acid, ammonium metatungstate, and tungsten oxide; and the hydrogenation metal is selected from at least one of Ni, Fe, Cu, Pt, Pd, Ru and Rh; and / or The method of any one of claims 8 to 12, wherein the retro-aldol catalyst metal is selected from at least one of W, Mo, and Ce.

14. Use of the catalyst according to any one of claims 1 to 7 in the production of glycols from polyhydroxy compounds.

15. 1. A method for producing glycol, comprising: The process comprises hydrolyzing and hydrogenating a polyhydroxy compound in the presence of hydrogen and the catalyst according to any one of claims 1 to 7 to produce glycols, Preferably, the weight ratio of the polyhydroxy compound to the catalyst is in the range of 10 to 0.1; and / or the weight ratio of water to the polyhydroxy compound is in the range of 30 to 300:1; and / or The initial hydrogen charging pressure is in the range of 0.5 to 10 MPa, and / or The hydrolysis and hydrogenation conditions include a reaction temperature of 150 to 300°C and a reaction time of 0.5 to 12 hours; and / or The method, wherein the polyhydroxy compound is selected from at least one of starch, hemicellulose, sucrose, glucose, fructose, furfural, and fructan.

Images