Composite catalyst as well as preparation method and application thereof

Abstract

The invention relates to a composite catalyst and a preparation method and application thereof. The preparation method comprises the following steps: S1, a catalyst precursor, a crosslinking agent raw material, water and phosphoric acid are mixed to obtain a reaction mixture, the catalyst precursor comprises a BaCO3 carrier, a first active component and a second active component, the first active component and the second active component are loaded on the BaCO3 carrier, the first active component comprises RuO2, the second active component comprises an oxide of metal M, and the first active component and the second active component are loaded on the BaCO3 carrier; the metal M comprises Mn and / or Fe; the cross-linking agent raw material is selected from one or more of amino acid and diamine compounds; and S2, contacting the reaction mixture with hydrogen to carry out first hydrothermal reaction. According to the invention, the catalytic activity of the composite catalyst in a reaction for preparing 1, 5-pentanediamine through lysine decarboxylation is improved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of catalyst synthesis, in particular, to a composite catalyst and a preparation method and application thereof. BACKGROUND

[0002] Amide materials have good mechanical properties, high heat resistance, wear resistance, chemical corrosion resistance, self-lubrication and other advantages. The structures of pentanediamine and hexanediamine are similar, and they can form polyamide material nylon 56 with excellent performance through polymerization with dibasic acid. The raw material for producing nylon 66 and other nylon products is hexanediamine, which depends on petrochemical synthesis. However, oil resources are becoming increasingly scarce, and the production process is seriously polluting the environment. Therefore, the production of polyamide PA56 using pentanediamine and other raw materials will occupy a large market share in the future polyamide market and have broad development prospects.

[0003] Preparation of pentanediamine by decarboxylation of lysine is an ideal synthesis route. Compared with decarboxylase and strains used in biological methods, heterogeneous catalysts generally have good stability and are not affected by diamine products, and the products are easy to separate from the catalyst. However, in the process of decarboxylation of L-lysine by heterogeneous catalysis, there are side reactions such as hydrogenation, decarboxylation and ring formation, including: (1) decarboxylation to pentanediamine, and then pentanediamine is deaminated to release piperidine; (2) partial hydrogenation to lysinol or complete hydrogenation to 1,5-hexanediamine, where they can also participate in deamination to produce 2-hydroxymethylpiperidine or 2-methylpiperidine, respectively, and (3) direct deamination to 2-piperidine-2-carboxylic acid, 2-piperidine-2-carboxylic acid, etc.

[0004] In previous literature, Verduyckt et al. used Ru / C catalysts to convert L-lysine in acidic aqueous solution with 100% conversion, and the yield of 1,5-pentanediamine was 32%, while the yield of the by-product lysinol reached 42% (ACS Sustain. Chem. Eng., 2017, 5, 3290). Huang et al. developed a Mn-doped RuO2-Mn-Beta catalyst, and the conversion of L-lysine was 100%, and the selectivity of 1,5-pentanediamine was 54% (ACS Sustain. Chem. Eng., 2021, 9, 13480). The side reaction of intermediate lysinol leads to a low yield of 1,5-pentanediamine. Therefore, the acid and reduction resistance of RuO2-based catalysts and their catalytic performance in the reaction of lysine decarboxylation to prepare 1,5-pentanediamine still need to be further improved. SUMMARY

[0005] The purpose of the present disclosure is to provide a composite catalyst and a preparation method and application thereof to solve the technical problems of poor acid resistance and reduction resistance of supported RuO2-based catalysts and poor selectivity of 1,5-pentanediamine in the process of lysine decarboxylation.

[0006] To achieve the above objectives, the first aspect of this disclosure provides a method for preparing a composite catalyst, comprising the following steps:

[0007] S1. The catalyst precursor, the crosslinking agent raw material, water and phosphoric acid are mixed to obtain a reaction mixture. The catalyst precursor includes a BaCO3 support and a first active component and a second active component supported on the BaCO3 support. The first active component includes RuO2, and the second active component includes an oxide of metal M, wherein metal M includes Mn and / or Fe. The crosslinking agent raw material is selected from one or more amino acids and diamine compounds.

[0008] S2. The reaction mixture is brought into contact with hydrogen to carry out a first hydrothermal reaction.

[0009] Optionally, in step S1, the catalyst precursor, based on the weight of the BaCO3 support, has the following composition: the content of the first active component is 2-8% by weight, preferably 5-6% by weight; the content of the second active component is 1-5% by weight, preferably 3-5% by weight, wherein the loading of the first and second active components is calculated in terms of metal elements.

[0010] Preferably, the molar ratio of the first active component to the second active component, based on metal elements, is 1:0.5 to 2.0, and more preferably 1:1.1 to 1.9.

[0011] Optionally, in step S1, the weight ratio of the catalyst precursor, the crosslinking agent raw material, and water is 1:0.5-2:700-900, preferably 1:0.9-1.1:750-850; phosphoric acid is added to make the pH of the reaction mixture 1-5, preferably 1.5-2.5.

[0012] Optionally, the amino acid is selected from one or both of L-lysine and L-isoleucine; the diamine compound is selected from one or both of 1,5-pentanediamine and 1,4-pentanediamine.

[0013] Optionally, in step S2, the conditions for the first hydrothermal reaction include: an initial hydrogen pressure of 1-4 MPa, preferably 1.5-2.5 MPa; a hydrothermal reaction temperature of 150-200°C, preferably 160-180°C; and a hydrothermal reaction time of 2-4 h, preferably 2.5-3.5 h.

[0014] Preferably, for every 0.1g of the catalyst precursor, the hydrogen pressure is 1-4MPa, more preferably 1.5-2.5MPa.

[0015] Optionally, the catalyst precursor is prepared by a method comprising the steps A1 to A2:

[0016] A1. Mix the first active metal source, the second active metal source, the alkali and BaCO3, and carry out an impregnation-coprecipitation reaction;

[0017] A2. The product obtained in step A1 is subjected to calcination treatment.

[0018] Optionally, in step A1, the first active metal source is a water-soluble salt of Ru; optionally, the first active metal source is selected from one or two of RuCl3 and Ru(Ac)3; the second active metal source is selected from a water-soluble salt of metal M; preferably, the water-soluble salt of metal Mn is selected from one or two of Mn(NO3)2 and Mn(Ac)2; the water-soluble salt of metal Fe is selected from one or two of Fe(NO3)3 and FeCl3;

[0019] Preferably, based on the weight of BaCO3, in step A1, the loading of the first active metal source is 2-8% by weight, preferably 5-6% by weight; the loading of the second active metal source is 1-5% by weight, preferably 3-5% by weight, wherein the loading of the first and second active metal sources is calculated in terms of metal elements.

[0020] Optionally, in step A1, the alkali is used in the form of an alkaline solution, the concentration of which is 1-4 mol / L, preferably 1-1.5 mol / L; the alkali is selected from one or more of NaOH, KOH, Ca(OH)2, Ba(OH)2, Na2CO3, NaHCO3, K2CO3, and KHCO3; preferably, in step A1, the ratio of the solid weight of the alkali to the total weight of the first active metal source and the second active metal source is 1-1.5:1, preferably 1.2-1.5:1.

[0021] Optionally, in step A1, the conditions for the impregnation-coprecipitation reaction include: a reaction temperature of 10–50°C and a reaction time of 0.5–3 h; preferably, the reaction temperature is 20–30°C and the reaction time is 2–3 h.

[0022] Optionally, the calcination conditions in step A2 include: a calcination temperature of 300–800°C and a calcination time of 1–5 h; preferably, the calcination temperature is 300–500°C and the calcination time is 1–3 h.

[0023] The second aspect of this disclosure provides a composite catalyst prepared according to the method described in the first aspect of this disclosure.

[0024] Optionally, the composite catalyst comprises a BaHPO4 support and a first active metal component and a second active metal component supported on the support; the first active metal component comprises Ru and RuO2, and the second active metal component comprises an oxide of metal M, wherein metal M comprises Mn and / or Fe.

[0025] Optionally, based on the total weight of the catalyst, the content of Ru is 0.3-2% by weight, the content of RuO2 is 2-4% by weight, and the content of the second active metal component is 1-20% by weight; preferably, the content of Ru is 0.9-1.4% by weight, the content of RuO2 is 3.4-3.8% by weight, and the content of the second active metal component is 5-8% by weight.

[0026] Optionally, the composite catalyst has a pore size of 2–9 nm.

[0027] The third aspect of this disclosure provides the application of the composite catalyst described in the second aspect of this disclosure in the decarboxylation reaction of lysine to prepare 1,5-pentanediamine.

[0028] Optionally, the reaction for the decarboxylation of lysine to prepare 1,5-pentanediamine includes the following steps:

[0029] Lysine, water, and a pH adjuster are contacted with the composite catalyst; a second hydrothermal reaction is carried out in the presence of hydrogen.

[0030] Preferably, the weight ratio of lysine, water and the composite catalyst is 0.5-2:700-900:1, more preferably 0.9-1.1:750-850:1; the pH adjuster is selected from one or more of phosphoric acid, acetic acid and lactic acid, and optionally, the pH of the reaction system is controlled to be 1-5;

[0031] Preferably, the conditions for the second hydrothermal reaction include: a hydrogen pressure of 1-4 MPa, preferably 1.5-2.5 MPa, a reaction temperature of 150-200°C, preferably 160-180°C, and a reaction time of 2-4 h, preferably 2.5-3.5 h.

[0032] Through the above technical solution, this disclosure provides a composite catalyst, its preparation method, and its application. This disclosure employs a catalyst precursor (an oxide of RuO2 and metal M supported on BaCO3) and an aqueous solution of amino acids to undergo a first hydrothermal reaction in the presence of hydrogen to obtain the composite catalyst. In the first hydrothermal reaction, Ru@RuO2-MO is synthesized through an "in-situ crosslinking-encapsulation" strategy. XThe composite catalyst prepared in this disclosure contains both Ru and RuO2, exhibiting superior resistance to acidic solutions and excessive hydrogen reduction. It maintains good stability under high-temperature acidic solutions and reducing hydrogen, and retains high selectivity for 1,5-pentanediamine even after multiple cycles. Furthermore, the presence of an oxide of metal M enhances the interaction between the oxide particles and the in-situ formed BaHPO4 support, resulting in a low loss rate and excellent cycle stability. In the L-lysine decarboxylation reaction to 1,5-pentanediamine, the composite catalyst provided in this disclosure effectively improves the lysine conversion rate and 1,5-pentanediamine selectivity, and the catalyst is recyclable while maintaining good catalytic performance.

[0033] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Detailed Implementation

[0034] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure. The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0035] The first aspect of this disclosure provides a method for preparing a composite catalyst, comprising the following steps:

[0036] S1. The catalyst precursor, the crosslinking agent raw material, water and phosphoric acid are mixed to obtain a reaction mixture. The catalyst precursor includes a BaCO3 support and a first active component and a second active component supported on the BaCO3 support. The first active component includes RuO2, and the second active component includes an oxide of metal M, wherein metal M includes Mn and / or Fe. The crosslinking agent raw material is selected from one or more amino acids and diamine compounds.

[0037] S2. The reaction mixture is brought into contact with hydrogen to carry out a first hydrothermal reaction.

[0038] This disclosure provides a method for preparing a composite catalyst, which involves a first hydrothermal reaction of a catalyst precursor (an oxide of RuO2 and metal M supported on BaCO3) with an aqueous solution of amino acids in the presence of hydrogen to obtain the composite catalyst. In the first hydrothermal reaction, Ru@RuO2-MO is synthesized through an "in-situ crosslinking-encapsulation" strategy.X The composite catalyst prepared in this disclosure contains both Ru and RuO2, exhibiting superior resistance to acidic solutions and excessive hydrogen reduction. It maintains good stability under high-temperature acidic solutions and reducing hydrogen, and retains high selectivity for 1,5-pentanediamine even after multiple cycles. Furthermore, the presence of an oxide of metal M enhances the interaction between the oxide particles and the in-situ formed BaHPO4 support, resulting in a low loss rate and excellent cycle stability. In the L-lysine decarboxylation reaction to 1,5-pentanediamine, the composite catalyst provided in this disclosure effectively improves the lysine conversion rate and 1,5-pentanediamine selectivity, and the catalyst is recyclable while maintaining good catalytic performance.

[0039] The specific principle of the "in-situ crosslinking-encapsulation" strategy disclosed herein includes: during the preparation of the composite catalyst, the reaction mixture undergoes a hydrothermal reaction, and the temperature needs to be gradually increased to the hydrothermal reaction temperature (e.g., 170°C). At this point, the catalyst precursor RuO2-MO... X BaCO3 will gradually dissolve, releasing Ba... 2+ and CO3 2- Ba 2+ With HPO4 in solution 2- The catalyst recombines to form solid BaHPO4, while most of the RuO2 nanoparticles are encapsulated within the BaHPO4 support during this process, which is completed as the temperature rises to the hydrothermal reaction temperature. At this point, the catalyst has become rock-like particles with regular facets. During this process, the exposed RuO2 is gradually reduced to Ru under the influence of H2. 0 (Ru on the catalyst surface) 0 Ru 0 The RuO2 content is approximately 26.5%. The added amino acid aqueous solution, under hydrothermal reaction conditions, will be reacted with a small amount of Ru. 0 Catalysis produces diamine compounds. These diamine compounds, as terminal diamines, can act as "crosslinking agents" to bind the already formed rock-like Ru@RuO2-MO. X / BaHPO4 gradually gelled together. During the process from heating to the hydrothermal reaction temperature to the hydrothermal acidification time, the inventors of this disclosure discovered that the composite catalyst Ru@RuO2-MO... X The particle size of / BaHPO4 increased from 15.2×14.5×5.2μm to 35.7×25.9×13.3μm, and then the size did not change. This also indicates that the diamine compound generated in situ from amino acids played the role of a crosslinking agent.

[0040] In one embodiment, in step S1, based on the weight of the BaCO3 support, the content of the first active component is 2-8% by weight, preferably 5-6% by weight; the content of the second active component is 1-5% by weight, preferably 3-5% by weight. In the preparation method provided in this disclosure, using a catalyst precursor with the optimized content composition of this embodiment, especially with the preferred content composition, the prepared composite catalyst has better catalytic performance.

[0041] In a preferred embodiment, the molar ratio of the first active component to the second active component, based on metal elements, is 1:0.5 to 2.0, preferably 1:1.1 to 1.9. The catalyst precursor provided in this embodiment has a suitable molar ratio of the first active component to the second active component, which can further improve the catalytic activity of the prepared composite catalyst.

[0042] In one embodiment, in step S1, the weight ratio of the catalyst precursor: amino acid: water is 1:0.5-2:700-900, preferably 1:0.9-1.1:750-850. According to the weight ratio provided in this embodiment, especially according to the preferred weight ratio range, a better "in-situ crosslinking-encapsulation" effect can be obtained, resulting in a composite catalyst with superior performance.

[0043] In one specific embodiment, the amino acid is selected from one or both of L-lysine and L-isoleucine, preferably L-lysine.

[0044] In one specific embodiment, phosphoric acid is added to adjust the pH of the reaction mixture to be between 1 and 5, preferably between 1.5 and 2.5.

[0045] In one embodiment, in step S2, the hydrothermal reaction conditions include: an initial hydrogen pressure of 1–4 MPa; a hydrothermal reaction temperature of 150–200 °C; and a hydrothermal reaction time of 2–4 h. Preferably, for every 0.1 g of the catalyst precursor, the hydrogen pressure is 1–4 MPa. The hydrothermal reaction conditions in this embodiment can prepare a composite catalyst with excellent catalytic performance in the decarboxylation of lysine to 1,5-pentanediamine.

[0046] In a preferred embodiment, in step S2, the hydrothermal reaction conditions include: an initial hydrogen pressure of 1.5–2.5 MPa; a hydrothermal reaction temperature of 160–180 °C; and a hydrothermal reaction time of 2.5–3.5 h. Preferably, for every 0.1 g of the catalyst precursor, the hydrogen pressure is 1.5–2.5 MPa. The optimized reaction conditions provided in this embodiment enable the preparation of composite catalysts with better catalytic performance.

[0047] In one specific embodiment, the catalyst precursor is prepared by a method including the following steps (impregnation-coprecipitation method):

[0048] A1. Mix the first active metal source, the second active metal source, the alkali and BaCO3, and carry out an impregnation-coprecipitation reaction;

[0049] A2. The precipitate obtained in step A1 is calcined. The above method can prepare a catalyst precursor, which is beneficial for the subsequent preparation of a composite catalyst capable of catalyzing the decarboxylation of lysine to prepare 1,5-pentanediamine.

[0050] In one embodiment, in step A1, the first active metal source is a water-soluble salt of Ru; optionally, the first active metal source is selected from one or two of RuCl3 and Ru(Ac)3; the second active metal source is selected from a water-soluble salt of metal M; preferably, the water-soluble salt of metal Mn is selected from one or two of Mn(NO3)2 and Mn(Ac)2; and the water-soluble salt of metal Fe is selected from one or more of Fe(NO3)3 and FeCl3.

[0051] In a preferred embodiment, in step A1, based on the weight of BaCO3, the loading of the first active metal source is 2-8% by weight, preferably 5-6% by weight; the loading of the second active metal source is 1-5% by weight, preferably 3-5% by weight.

[0052] Optionally, in step A1, the alkali is used in the form of an alkaline solution, the concentration of which is 1-4 mol / L, preferably 1-1.5 mol / L; the alkali is selected from one or more of NaOH, KOH, Ca(OH)2, Ba(OH)2, Na2CO3, NaHCO3, K2CO3 and KHCO3;

[0053] Preferably, in step A1, the ratio of the solid weight of the alkali to the total weight of the first and second active metal sources is 1 to 1.5:1, more preferably 1.2 to 1.5:1. According to the conditions of this embodiment, and especially the optimized conditions, the prepared catalyst precursor is more suitable for the subsequent preparation of the composite catalyst, thereby improving the catalytic performance of the composite catalyst.

[0054] In one embodiment, in step A1, the conditions for the precipitation reaction include: a reaction temperature of 10–50°C and a reaction time of 0.5–3 h; preferably, the reaction temperature is 20–30°C and the reaction time is 2–3 h.

[0055] Optionally, in step A2, the calcination conditions include: a calcination temperature of 300–800°C and a calcination time of 1–5 h; preferably, the calcination temperature is 300–500°C and the calcination time is 1–3 h. The catalyst precursor prepared according to the optimized conditions provided in this embodiment is more conducive to the preparation of composite catalysts in the presence of L-lysine and hydrogen.

[0056] The second aspect of this disclosure provides a composite catalyst prepared according to the method described in the first aspect of this disclosure.

[0057] In a preferred embodiment, the composite catalyst comprises a BaHPO4 support and a first active metal component and a second active metal component supported on the support; the first active metal component comprises Ru and RuO2, and the second active metal component comprises an oxide of metal M, wherein metal M comprises Mn and / or Fe. The composite catalyst provided in this disclosure uses BaHPO4 as a support and supports metal Ru and oxide RuO2, and introduces the oxide of metal M in conjunction with the elemental form and oxide of Ru, thereby achieving a low catalyst loss rate and excellent cycle stability.

[0058] In one embodiment, based on the total weight of the catalyst, the content of Ru is 0.3–2 wt%, the content of RuO2 is 2–4 wt%, and the content of the second active metal component is 1–20 wt%; preferably, the content of Ru is 0.9–1.4 wt%, the content of RuO2 is 3.4–3.8 wt%, and the content of the second active metal component is 5–8 wt%. When the component contents in the composite catalyst are within the range provided in this embodiment, the composite catalyst exhibits better catalytic performance in the decarboxylation reaction of lysine to prepare 1,5-pentanediamine.

[0059] In one specific embodiment, the composite catalyst has a pore size of 2–9 nm and a specific surface area of ​​2.89–4.63 m². 2 / g, pore volume of 0.003~0.008m 3 / g.

[0060] The third aspect of this disclosure provides the application of the composite catalyst described in the second aspect of this disclosure in the decarboxylation reaction of lysine to prepare 1,5-pentanediamine.

[0061] In one embodiment, the reaction for the decarboxylation of lysine to prepare 1,5-pentanediamine includes the following steps:

[0062] Lysine, water, and a pH adjuster are contacted with the composite catalyst; a second hydrothermal reaction is carried out in the presence of hydrogen.

[0063] In a preferred embodiment, the weight ratio of lysine, water, and the composite catalyst is 0.5–2:700–900:1, preferably 0.9–1.1:750–850:1; the pH adjuster is selected from one or more of phosphoric acid, acetic acid, and lactic acid, and optionally, the pH of the reaction system is controlled to be 1–5. By reacting according to the raw material weight ratio provided in this embodiment, a higher conversion rate of L-lysine and a higher selectivity for the product 1,5-pentanediamine can be obtained.

[0064] In a preferred embodiment, the conditions for the second hydrothermal reaction include: a hydrogen pressure of 1–4 MPa, preferably 1.5–2.5 MPa; a reaction temperature of 150–200°C, preferably 160–180°C; and a reaction time of 2–4 h, preferably 2.5–3.5 h. Performing the second hydrothermal reaction according to the conditions provided in this embodiment for the decarboxylation of lysine can yield a higher conversion rate of L-lysine and a higher selectivity for the product 1,5-pentanediamine.

[0065] The present disclosure is further described in detail below through examples. All raw materials used in the examples are commercially available.

[0066] The content of catalyst components was determined by XRD, XPS and ICP methods.

[0067] X-ray photoelectron spectroscopy (XPS) was performed on a Thermo Scientific K-Alpha spectrometer using an Al Kα source (hv = 1486.6 eV). During data analysis, the contamination peak of C1s (binding energy: 284.8 eV) was used as correction.

[0068] Inductively coupled plasma atomic emission spectrometry (ICP) was performed on a Thermo IRIS Intrepid II XSP using the external standard method. A certain amount of catalyst was weighed, dissolved thoroughly in HNO3, and diluted to 25 mL with deionized water to obtain the sample to be tested. During the test, the standard sample was tested first to obtain a standard curve, and then the sample was tested. Each sample was tested at least twice.

[0069] Powder X-ray diffraction (XRD) was performed using a Rigaku Ultima IV X-ray diffractometer (Japan). Except in special cases, samples must be thoroughly ground before testing. The instrument is equipped with Cu Kα rays. Test parameters: Test voltage: 35kV, test current: 25mA, scan range: 10–80°, scan speed: 10° / min, scan step size: 0.02°. XRD analysis was used to determine the phase changes of the catalyst during its preparation.

[0070] ICP performs qualitative analysis on samples based on the measured spectral wavelengths and quantitative analysis on metallic elements such as Ba, Ru, Mn, and Fe based on emission intensity. Within a certain concentration range, the intensity of characteristic spectral lines is directly proportional to the element concentration. A calibration curve for the target element is established with emission intensity as the ordinate and the mass concentration of the target element series as the abscissa. Under the same conditions as establishing the calibration curve, the emission intensity of the sample is measured. The content of the target element is then determined from the emission intensity value on the calibration curve. XPS can calculate the relative atomic concentration of different elements, i.e., using the element sensitivity factor method, using the spectral line intensity of a specific element as a reference standard, measuring the relative spectral line intensities of other elements, and calculating the relative content of each element; XPS testing can also analyze the relative atomic concentration of the same element in different chemical states, i.e., decomposing a broad peak in the range of 279–283 eV into its constituent single peaks, performing deconvolution, and thus obtaining the Ru concentration on the catalyst surface. 0 account for a total of Ru 0 +The proportion of RuO2 content, of which Ru 0 The peak position in the XPS spectrum is around 279.9 eV, and the peak position of RuO2 is around 280.6 eV;

[0071] The particle size of the composite catalyst was obtained by HRTEM testing;

[0072] The pore size of the composite catalyst was calculated using the BET method based on N2 adsorption-desorption experiments.

[0073] Example 1

[0074] This embodiment illustrates the preparation of composite catalysts:

[0075] (1) Weigh 2g of BaCO3 into a flask, add a certain amount of RuCl3 (first metal source) aqueous solution and Mn(NO3)2 (second metal source) to make the loading of Ru and Mn both 5% by weight (based on the weight of the carrier BaCO3). Stir at room temperature for 24h. Weigh 2.8g of KOH (alkaline solution) and dissolve it in 50mL of H2O until it is completely dissolved. Add 1mol / L KOH alkaline solution dropwise to the flask to make the Ru... 3+ and Mn 2+ Complete precipitation occurred, and the pH of the solution was greater than 13. After standing for a period of time, the solution was centrifuged, filtered, and washed until the pH of the supernatant was 7. The obtained solid was dried in an oven at 80°C for 24 hours and then calcined in a muffle furnace at 400°C for 2 hours to synthesize the catalyst precursor: RuO2-MnO2 / BaCO3; wherein, based on metal elements, the molar ratio of the first active component to the second active component was 1:1.84.

[0076] (2) Add 0.1g of the catalyst precursor RuO2-MnO2 / BaCO3 prepared in step (1) to the reactor, add 0.1g of lysine (crosslinking agent raw material), 80mL of H2O, and add H3PO4 to adjust the pH of the solution to 2. The weight ratio of catalyst precursor: crosslinking agent raw material: water is 1:1:800. Seal the reactor and introduce N2 to replace the air in the reactor. Introduce 2MPa of H2 into the reactor (for every 0.1g of the catalyst precursor, the hydrogen pressure is 2MPa), raise the temperature of the reactor to 170℃, and react for 3h (first hydrothermal reaction) to obtain the composite catalyst Ru@RuO2-MnO2 / BaHPO4, denoted as C1.

[0077] Comparative Example 1

[0078] This comparative example follows the preparation method in Example 1, but differs from Example 1 in that Mn(NO3)2 is not added in step (1), and a RuO2 / BaCO3 catalyst precursor is synthesized.

[0079] Step (2) is the same as in Example 1, and the catalyst Ru@RuO2 / BaHPO4 is obtained, denoted as D1.

[0080] Comparative Example 2

[0081] This embodiment refers to the preparation method in Example 1. The difference from Example 1 is that lysine is not added in step (2), that is, reduction is carried out only under hydrogen to obtain the catalyst, and D2 is recorded.

[0082] Comparative Example 3

[0083] This comparative example follows the preparation method in Example 1, but differs from Example 1 in that: in the catalyst preparation process, only the impregnation-coprecipitation method in step (1) is used, omitting the in-situ synthesis step in step (2), to prepare the RuO2-MnO2 / BaHPO4 catalyst precursor, including the following steps:

[0084] In step (1), BaHPO4 is used instead of BaCO3. 2g of BaHPO4 is weighed into a flask, and a certain amount of RuCl3 (first metal source) aqueous solution and Mn(NO3)2 (second metal source) are added, so that the loading of Ru and Mn is 5% by weight (based on the weight of the carrier). 2.8g of KOH is weighed and dissolved in 50mL of H2O until fully dissolved. A 1mol / L KOH alkaline solution is added dropwise to the flask, so that Ru... 3+ and Mn 2+Complete precipitation occurred, and the pH of the solution was greater than 13. The mixture was stirred at room temperature for 24 hours. After standing for a period of time, the solution was centrifuged, filtered, and washed until the pH of the supernatant was 7. The resulting solid was dried in an oven at 80°C for 24 hours and then calcined in a muffle furnace at 400°C for 2 hours. The composite catalyst RuO2-MnO2 / BaHPO4 was obtained, denoted as D3.

[0085] Example 2

[0086] This embodiment refers to the preparation method in Example 1. The difference from Example 1 is that in step (1), the manganese source is replaced with an iron source (Fe(NO3)3·9H2O) to synthesize the RuO2-Fe3O4 / BaCO3 catalyst precursor.

[0087] Step (2) is the same as step (2) in Example 1, and the composite catalyst Ru@RuO2-Fe3O4 / BaHPO4 is obtained, denoted as C2.

[0088] Example 3

[0089] This embodiment refers to the preparation method in Example 1. The difference from Example 1 is that in step (2), 0.1g of the prepared RuO2-MnO2 / BaCO3 catalyst precursor is added to the reactor, along with 1g of lysine, 80mL of H2O, and H3PO4 to adjust the pH of the solution to 2. The weight ratio of catalyst precursor:L-lysine (colloidal agent raw material):water is 1:10:800. The reactor is sealed, and the remaining process is the same as in Example 1, resulting in a composite catalyst, denoted as C3.

[0090] Example 4

[0091] This embodiment refers to the preparation method in Example 1, except that in step (2), 0.1g of the prepared RuO2-MnO2 / BaCO3 catalyst precursor is added to the reaction vessel, along with 0.05g of lysine, 80mL of H2O, and H3PO4 to adjust the pH of the solution to 2. The weight ratio of catalyst precursor:L-lysine:water is 1:0.5:800. The reaction vessel is sealed, and the remaining process is the same as in Example 1, yielding a composite catalyst, denoted as C4.

[0092] Example 5

[0093] This embodiment refers to the preparation method in Example 1, except that in step (2), 0.1g of the prepared RuO2-MnO2 / BaCO3 catalyst precursor is added to the reaction vessel, along with 0.2g of lysine, 80mL of H2O, and H3PO4 to adjust the pH of the solution to 2. The weight ratio of catalyst precursor:L-lysine:water is 1:2:800. The reaction vessel is sealed, and the remaining process is the same as in Example 1, yielding a composite catalyst, denoted as C5.

[0094] Example 6

[0095] This embodiment refers to the preparation method in Example 1, but differs from Example 1 in that:

[0096] The conditions for the first hydrothermal reaction in step (2) are as follows: 4 MPa H2 is introduced into the reactor (the amount of hydrogen gas used for each 0.1 g of the catalyst precursor is 4 MPa), the temperature of the reactor is raised to 250°C, and the reaction is carried out for 5 h to obtain the composite catalyst, which is denoted as C6.

[0097] Example 7

[0098] This embodiment refers to the preparation method in Example 1, but differs from Example 1 in that:

[0099] In step (2), lysine is replaced with 1,5-pentanediamine, and the rest of the process is the same as in Example 1, to obtain a composite catalyst, denoted as C7.

[0100] Example 8

[0101] This embodiment refers to the preparation method in Example 1, but differs from Example 1 in that:

[0102] In step (1), 2g of BaCO3 was weighed into a flask, and a certain amount of RuCl3 (first metal source) aqueous solution and Mn(NO3)2 (second metal source) were added to make the loading of Ru 2% by weight and the loading of Mn 1% by weight (based on the weight of the support BaCO3). The rest of the process was the same as in Example 1, and a catalyst precursor: RuO2-MnO2 / BaCO3 was synthesized; wherein, based on metal elements, the molar ratio of the first active component to the second active component was 1:0.92; the rest of the process was the same as in Example 1, and a composite catalyst was obtained, denoted as C8.

[0103] Example 9

[0104] This embodiment refers to the preparation method in Example 1, but differs from Example 1 in that:

[0105] Step (1) Weigh 2g of BaCO3 into a flask, add a certain amount of RuCl3 (first metal source) aqueous solution and Mn(NO3)2 (second metal source) to make the Ru loading 12 wt% and the Mn loading 0.02 wt% (based on the weight of the BaCO3 support). The rest of the process is the same as in Example 1, and a catalyst precursor: RuO2-MnO2 / BaCO3 is synthesized; wherein, based on metal elements, the molar ratio of the first active component to the second active component is 1:0.003; the rest of the process is the same as in Example 1, and a composite catalyst is obtained, denoted as C9.

[0106] Example 10

[0107] This embodiment refers to the preparation method in Example 1, but differs from Example 1 in that:

[0108] In step (2), lysine is replaced with L-isoleucine, and the rest of the process is the same as in Example 1, to obtain a composite catalyst, denoted as C10.

[0109] Example 11

[0110] This embodiment refers to the preparation method in Example 1, but differs from Example 1 in that:

[0111] In step (2), lysine is replaced with 1,4-pentanediamine, and the rest of the process is the same as in Example 1, to obtain a composite catalyst, denoted as C11.

[0112] The composition and particle size of the catalyst products prepared in the above examples and comparative examples are listed in Table 1 below.

[0113] Table 1

[0114]

[0115] The catalysts prepared in the above examples and comparative examples were used in the following reaction example for the decarboxylation of lysine to generate 1,5-pentanediamine to illustrate the catalytic effect of the catalysts.

[0116] Reaction Example 1

[0117] 0.1 g of the composite catalyst C1 prepared in Example 1 was added to a reaction vessel, along with 0.1 g of lysine, 80 mL of H2O, and H3PO4 to adjust the pH of the solution to 2. The weight ratio of lysine, water, and composite catalyst was 1:800:1. The reaction vessel was sealed, and N2 was introduced to replace the air in the reaction vessel. 2 MPa of H2 was introduced into the reaction vessel, and the temperature of the reaction vessel was raised to 170 °C. The reaction was carried out for 3 h (second hydrothermal reaction). After the reaction was completed, the vessel was cooled to release H2. The reaction solution was then obtained by opening the vessel and quantitative analysis was performed by liquid chromatography. The product distribution is shown in Table 2.

[0118] Reactions 2-11 and Comparative Reactions 1-3

[0119] The method in Reaction Example 1 was followed, except that the composite catalyst was replaced with catalysts C2 to C11 and D1 to D3 respectively. The other reaction conditions were the same as in Reaction Example 1. Quantitative analysis was performed by liquid chromatography, and the product distribution is listed in Table 2.

[0120] Reaction Example 12

[0121] This reaction example follows the method in Reaction Example 1, but differs from Reaction Example 1 in the following ways:

[0122] 0.1 g of the composite catalyst C1 prepared in Example 1 was added to a reaction vessel, along with 1 g of lysine and 80 mL of H2O, wherein the weight ratio of lysine, water, and composite catalyst was 10:800:1; and H3PO4 was added to adjust the pH of the solution to 2. The remaining process was the same as in reaction example 1. The reaction solution was obtained after opening the vessel and quantitatively analyzed by liquid chromatography. The product distribution is listed in Table 2.

[0123] Reaction Example 13

[0124] This reaction example follows the method in Reaction Example 1, but differs from Reaction Example 1 in the following ways:

[0125] 0.1 g of the composite catalyst C1 prepared in Example 1 was added to a reaction vessel, along with 0.05 g of lysine and 80 mL of H2O. The weight ratio of lysine, water, and composite catalyst was 0.5:800:1. H3PO4 was added to adjust the pH of the solution to 2. The remaining process was the same as in Example 1. The reaction solution was obtained after opening the vessel and quantitatively analyzed by liquid chromatography. The product distribution is shown in Table 2.

[0126] Reaction Example 14

[0127] This reaction example follows the method in Reaction Example 1, but differs from Reaction Example 1 in the following ways:

[0128] 0.1 g of the composite catalyst C1 prepared in Example 1 was added to a reaction vessel, along with 0.2 g of lysine and 80 mL of H2O. The weight ratio of lysine, water, and composite catalyst was 2:800:1. H3PO4 was added to adjust the pH of the solution to 2. The remaining process was the same as in Example 1. The reaction solution was obtained after opening the vessel and quantitatively analyzed by liquid chromatography. The product distribution is shown in Table 2.

[0129] Reaction Example 15

[0130] This reaction example follows the method in Reaction Example 1, but differs from Reaction Example 1 in the following ways:

[0131] The reactor was sealed, and N2 was introduced to replace the air in the reactor. 4 MPa of H2 was then introduced into the reactor, and the temperature was raised to 250°C. The reaction was allowed to proceed for 6 hours. After the reaction was complete, the reactor was cooled to release the H2. The reaction solution was then opened and quantitatively analyzed by liquid chromatography. The product distribution is shown in Table 2.

[0132] In the above reaction examples and comparative examples, the instrument used to analyze the composition of the liquid phase products was a Waters high-performance liquid chromatograph, the chromatographic column was a C18 reversed-phase column, the detector was an ultraviolet absorption detector, and the mobile phase was a mixed solution of 60% acetonitrile and 40% aqueous acetic acid solution.

[0133] The conversion rate of L-lysine and the selectivity and yield of the product 1,5-pentanediamine were calculated using the following formulas (1) to (3):

[0134]

[0135] The test results of the above reaction examples and reaction comparison examples are listed in Table 2 below.

[0136] Table 2

[0137]

[0138] Based on the data in Tables 1 and 2 above, it can be seen that:

[0139] Comparing Reaction Example 1 with Reaction Comparative Example 1, the catalyst D1 used in Reaction Comparative Example 1 does not contain a second active metal component, and catalyst D1 has poor catalytic effect and recycling stability in the decarboxylation reaction of lysine to 1,5-pentanediamine; while Reaction Example 1 uses the composite catalyst C1 provided in this disclosure, and Reaction Example 1 has higher selectivity and yield of the product 1,5-pentanediamine, and the selectivity of 1,5-pentanediamine is higher after the catalyst is recycled 6 times;

[0140] Comparing reaction example 1 with reaction comparison example 2, reaction comparison example 2 used catalyst D2, which did not contain lysine as a crosslinking agent during preparation. The catalyst particles obtained in comparison example 2 were also smaller, making it impossible to achieve the "in-situ crosslinking-encapsulation" effect. Catalyst D2 had poor catalytic effect and poor recycling stability in the decarboxylation reaction of lysine to 1,5-pentanediamine. In contrast, reaction example 1, which used the composite catalyst C1 provided in this disclosure, had a higher conversion rate of L-lysine and higher selectivity and yield of the product 1,5-pentanediamine. Furthermore, the 1,5-pentanediamine selectivity was higher after the catalyst was recycled 6 times.

[0141] Comparing Reaction Example 1 with Reaction Comparative Example 3, the catalyst D3 in Reaction Comparative Example 3 was not prepared using the "in-situ crosslinking-encapsulation" preparation method provided in this disclosure. The selectivity and yield of 1,5-pentanediamine in Reaction Comparative Example 3 were both low, and the selectivity of 1,5-pentanediamine after six catalyst cycles was also low. The composite catalyst prepared in Reaction Example 1 using the method provided in this disclosure has better catalytic performance, and the selectivity of 1,5-pentanediamine after six catalyst cycles is higher.

[0142] Comparing Reaction Examples 4-5 with Reaction Example 3, the composite catalysts C4-C5 used in Reaction Examples 4-5 had a catalyst precursor:L-lysine:water weight ratio within the optimized range provided in this disclosure during preparation. In contrast, catalyst C3 used in Reaction Example 3 had an excess of binder raw material (L-lysine) added during preparation. Compared to Reaction Example 3, the composite catalysts in Reaction Examples 4-5 exhibited better catalytic activity and recycling stability. Furthermore, comparing Reaction Examples 4-5 with Reaction Example 1, the catalyst precursor:L-lysine:water weight ratio in Reaction Example 1 was within the further preferred range provided in this disclosure. Compared to Reaction Examples 4-5, Reaction Example 1 showed higher L-lysine conversion, as well as higher selectivity and yield of the product 1,5-pentanediamine. Moreover, catalyst C1 exhibited higher selectivity for 1,5-pentanediamine after six recycling cycles.

[0143] Comparing Reaction Example 8 with Reaction Example 9, the composition of the catalyst precursor used in the preparation process of composite catalyst C8 in Reaction Example 8 is within the optimized range provided in this disclosure, while the composition of the catalyst precursor used in the preparation process of catalyst C9 in Reaction Example 9 is not within the optimized range. Compared with Reaction Example 9, Reaction Example 8 has a higher conversion rate of L-lysine and a higher selectivity and yield of the product 1,5-pentanediamine, and the 1,5-pentanediamine selectivity is also higher after the catalyst is recycled 6 times. Further comparing Reaction Example 8 with Reaction Example 1, the composition of the catalyst precursor used in the preparation process of composite catalyst C1 in Reaction Example 1 is within the further preferred range provided in this disclosure. Reaction Example 1 has a higher conversion rate of L-lysine and a higher selectivity and yield of the product 1,5-pentanediamine, and the 1,5-pentanediamine selectivity is higher after the catalyst C1 is recycled 6 times.

[0144] Comparing Reaction Example 12 with Reaction Examples 13-14, 13-14 were conducted to prepare 1,5-pentanediamine by decarboxylation of lysine according to the optimized weight ratio of lysine, water and composite catalyst provided in this disclosure, while the weight ratio of the starting materials in Reaction Example 12 was not within the optimized range provided in this disclosure. The conversion rate of L-lysine and the selectivity and yield of the product 1,5-pentanediamine in Reaction Examples 13-14 were higher than those in Reaction Example 12. Comparing Reaction Example 1 with Reaction Examples 13-14, 13-14 were conducted according to a more preferred weight ratio of lysine, water and composite catalyst, and Reaction Example 1 had better reaction performance.

[0145] Comparing Reaction Example 1 with Reaction Example 15, it can be seen that Reaction Example 1, which carried out the decarboxylation of lysine to prepare 1,5-pentanediamine under the optimized reaction conditions provided in this disclosure, has a higher conversion rate of L-lysine and a higher selectivity and yield of the product 1,5-pentanediamine.

[0146] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0147] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0148] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A process for preparing a composite catalyst, characterized by, The method comprises the following steps: S1, mixing a catalyst precursor, a glue linker raw material, water and phosphoric acid to obtain a reaction mixture, wherein the catalyst precursor comprises a BaCO3 carrier and a first active component and a second active component supported on the BaCO3 carrier, the first active component comprises RuO2, and the second active component comprises an oxide of a metal M, and the metal M comprises Mn and / or Fe; the glue linker raw material is selected from one or more of amino acids and diamine compounds; S2, contacting the reaction mixture with hydrogen to perform a first hydrothermal reaction.

2. The method of claim 1, wherein, In step S1, the content of the first active component is 2-8 wt%, preferably 5-6 wt%, based on the weight of the BaCO3 carrier; and the content of the second active component is 1-5 wt%, preferably 3-5 wt%, based on the weight of the BaCO3 carrier, wherein the loading amount of the first active component and the second active component is calculated based on metal elements. Preferably, the molar ratio of the first active component to the second active component is 1:0.5-2.0, preferably 1:1.1-1.9, based on metal elements.

3. The method of claim 1, wherein, In step S1, the weight ratio of the catalyst precursor to the glue linker raw material to water is 1:0.5-2:700-900, preferably 1:0.9-1.1:750-850; and the phosphoric acid is added to make the pH value of the reaction mixture be 1-5, preferably 1.5-2.

5. Optionally, the amino acid is selected from one or both of L-lysine and L-isoleucine; and the diamine compound is selected from one or both of 1,5-pentanediamine and 1,4-pentanediamine.

4. The method of claim 1, wherein, In step S2, the conditions of the first hydrothermal reaction comprise that the initial pressure of hydrogen is 1-4 MPa, preferably 1.5-2.5 MPa; the hydrothermal reaction temperature is 150-200°C, preferably 160-180°C; and the hydrothermal reaction time is 2-4 h, preferably 2.5-3.5 h. Preferably, the pressure of hydrogen is 1-4 MPa, preferably 1.5-2.5 MPa, per 0.1 g of the catalyst precursor.

5. The method of claim 1, wherein, The catalyst precursor is prepared by a method comprising the following steps A1-A2: A1, mixing a first active metal source, a second active metal source, a base and BaCO3 to perform an impregnation-co-precipitation reaction; A2, performing a calcination treatment on the product obtained in step A1.

6. The method of claim 5, wherein, In step A1, the first active metal source is a water-soluble salt of Ru; optionally, the first active metal source is selected from one or both of RuCl3 and Ru(Ac)3; and the second active metal source is selected from a water-soluble salt of a metal M; preferably, the water-soluble salt of the metal M is selected from one or both of Mn(NO3)2 and Mn(Ac)2; and the water-soluble salt of the metal Fe is selected from one or both of Fe(NO3)3 and FeCl3. Preferably, in step A1, the loading amount of the first active metal source is 2-8 wt%, preferably 5-6 wt%, and the loading amount of the second active metal source is 1-5 wt%, preferably 3-5 wt%, based on the weight of BaCO3, wherein the loading amount of the first active metal source and the second active metal source are calculated based on the metal element; Optionally, in step A1, the base is used in the form of a base solution, the concentration of the base solution is 1-4 mol / L, preferably 1-1.5 mol / L; the base is selected from one or more of NaOH, KOH, Ca(OH)2, Ba(OH)2, Na2CO3, NaHCO3, K2CO3 and KHCO3; preferably, in step A1, the ratio of the solid weight of the base to the total weight of the first active metal source and the second active metal source is 1-1.5:1, preferably 1.2-1.5:

1.

7. The method of claim 5, wherein, In step A1, the conditions of the impregnation-coprecipitation reaction include: the reaction temperature is 10-50℃, and the reaction time is 0.5-3h; preferably, the reaction temperature is 20-30℃, and the reaction time is 2-3h; Optionally, in step A2, the conditions of the calcination treatment include: the calcination temperature is 300-800℃, and the calcination time is 1-5h; preferably, the calcination temperature is 300-500℃, and the calcination time is 1-3h.

8. The composite catalyst prepared by the method of any one of claims 1-7.

9. The composite catalyst of claim 8, wherein, The composite catalyst comprises a BaHPO4 carrier and a first active metal component and a second active metal component supported on the carrier; the first active metal component comprises Ru and RuO2, and the second active metal component comprises an oxide of a metal M, wherein the metal M comprises Mn and / or Fe.

10. The composite catalyst of claim 9, wherein The content of Ru is 0.3-2 wt%, the content of RuO2 is 2-4 wt%, and the content of the second active metal component is 1-20 wt%, based on the total weight of the catalyst; preferably, the content of Ru is 0.9-1.4 wt%, the content of RuO2 is 3.4-3.8 wt%, and the content of the second active metal component is 5-8 wt%; Optionally, the pore size of the composite catalyst is 2-9 nm.

11. The use of the composite catalyst of any one of claims 8-10 in a reaction for preparing 1,5-pentanediamine by decarboxylation of lysine.

12. Use according to claim 11, characterized in that, The reaction for preparing 1,5-pentanediamine by decarboxylation of lysine comprises the following steps: lysine, water, a pH regulator and the composite catalyst are contacted; and a second hydrothermal reaction is carried out in the presence of hydrogen; Preferably, the weight ratio of lysine, water and the composite catalyst is 0.5-2:700-900:1, preferably 0.9-1.1:750-850:1; the pH regulator is selected from one or more of phosphoric acid, acetic acid and lactic acid; optionally, the pH of the reaction system is controlled to be 1-5. Preferably, the conditions of the second hydrothermal reaction include: hydrogen pressure of 1-4 MPa, preferably 1.5-2.5 MPa, reaction temperature of 150-200°C, preferably 160-180°C, and reaction time of 2-4 h, preferably 2.5-3.5 h.

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