Molybdenum-based composite oxide catalyst, preparation method and application thereof and method for preparing pyruvic acid from lactic acid

Abstract

This invention relates to the field of pyruvate preparation technology, and discloses a molybdenum-based composite oxide catalyst, its preparation method and application, and a method for preparing pyruvate from lactic acid. The molybdenum-based composite oxide catalyst contains a support and a catalyst with the general formula Mo1V. a X b A c B d C e O x The active component comprises X selected from one or more of bismuth, niobium, indium, and antimony; A selected from one or more of potassium, rubidium, and cesium; B selected from one or more of boron and phosphorus; and C selected from one or more of iron and cobalt. a = 0.1–1.5, b = 0.001–0.025, c = 0.001–0.015, d = 0.001–0.01, e = 0.002–0.025, where x is the number of oxygen atoms required to satisfy the valence equilibrium requirements of other non-oxygen elements in the active component. This molybdenum-based composite oxide catalyst exhibits high lactic acid conversion, low pyruvate selectivity, and high pyruvate yield in the reaction of lactic acid to pyruvate.

Description

Technical Field

[0001] This invention relates to the field of pyruvate preparation technology, specifically to a molybdenum-based composite oxide catalyst, its preparation method and application, and a method for preparing pyruvate from lactic acid. Background Technology

[0002] Pyruvate, as a valuable organic intermediate, contains both carbonyl and carboxyl groups in its molecule, offering broad application prospects. It has practical applications in various fields such as chemical engineering, pharmaceuticals, food, and agriculture, and can also serve as an initiator for ethylene polymers. Furthermore, pyruvate-based substances are used in medicine to treat common diseases such as tumors, ulcers, and osteoporosis. Of particular note is calcium pyruvate, a key ingredient in commercially available weight-loss drugs, which is currently experiencing rapid sales growth and is very popular, indicating promising development prospects. Currently, pyruvate preparation processes are broadly classified into two categories: biotechnology and chemical synthesis. Biotechnology mainly includes fermentation and enzyme catalysis, but this method results in low pyruvate yields and high separation costs. Among chemical methods, the tartaric acid method and the lactic acid (salt) method are two of the most representative synthetic processes. However, the tartaric acid method faces difficulties such as low yield, heavy pollution, and high costs, resulting in a loss of product competitiveness and thus restricting the expansion of pyruvate production scale. The lactic acid catalytic oxidation method uses lactic acid as a raw material and oxygen or air as an oxidant to synthesize pyruvate. Lactic acid is a typical fermentation product of corn, with wide availability and low cost. Utilizing lactic acid to produce pyruvate is a clean production process that not only reduces the production cost of pyruvate and overcomes the problem of heavy environmental pollution, but also greatly increases the practical application value of lactic acid. Therefore, finding a highly efficient, low-consumption, and inexpensive catalyst to catalyze the production of pyruvate from lactic acid would be extremely economically beneficial.

[0003] Currently, there is limited research on the preparation of pyruvate from lactic acid, and the yield of pyruvate and the conversion rate of lactic acid are affected by various factors, such as catalyst type, temperature, morphology, particle size, and crystal structure. Patent CN108640829B proposes a method for preparing pyruvate from lactic acid using aqueous-phase catalytic oxidation with supported nano-magnesium oxide as a catalyst. This method achieves a higher pyruvate yield than existing gas-phase oxidation methods, and the product is easily separated from the catalyst, which can be recycled. CN108069850A uses a supported catalyst with Pt and / or Pd as the main active components to catalyze the one-step oxidative dehydrogenation of lactic acid to obtain pyruvate in aqueous solution, effectively improving both lactic acid conversion and pyruvate yield. CN112479262A provides a process for preparing pyruvate from lactic acid using iron oxide and a fixed-bed reactor. This process not only improves catalyst activity but also increases both lactic acid conversion and pyruvate yield, while maintaining low production costs. In addition, some literature, such as Sam et al., reported the gas-phase catalytic synthesis of pyruvate using Nb-Ni-O as a bimetallic catalyst, achieving a lactic acid conversion rate of 30.5% and a pyruvate selectivity of 50.3%. Overall, some catalysts suffer from low lactic acid conversion and selectivity, complex byproducts, and low catalyst stability. There is an urgent need to find a catalyst that can improve both lactic acid conversion and pyruvate selectivity. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of low lactic acid conversion rate, low pyruvate selectivity, and low pyruvate yield in existing technologies for preparing pyruvate from lactic acid. This invention provides a molybdenum-based composite oxide catalyst, its preparation method and application, and a method for preparing pyruvate from lactic acid. This molybdenum-based composite oxide catalyst has excellent catalytic performance and can achieve high lactic acid conversion rate, pyruvate selectivity, and pyruvate yield in the reaction of lactic acid to pyruvate.

[0005] To achieve the above objectives, a first aspect of the present invention provides a molybdenum-based composite oxide catalyst, wherein the molybdenum-based composite oxide catalyst comprises a support and a catalyst of the general formula Mo1V. a X b A c B d C e O x The active components;

[0006] Wherein, X is selected from one or more of bismuth, niobium, indium, and antimony; A is selected from one or more of potassium, rubidium, and cesium; B is selected from boron and / or phosphorus; and C is selected from iron and / or cobalt.

[0007] a, b, c, d, e, and x represent the atomic proportions of the corresponding elements, where a = 0.1-1.5, b = 0.001-0.025, c = 0.001-0.015, d = 0.001-0.015, e = 0.002-0.025, and x is the number of oxygen atoms required in the active component to satisfy the valence equilibrium requirements of other non-oxygen elements.

[0008] A second aspect of this invention provides a method for preparing a molybdenum-based composite oxide catalyst, the method comprising the following steps:

[0009] (1) Dissolve molybdenum-containing compounds, vanadium-containing compounds, X-containing compounds, A-containing compounds, B-containing compounds and C-containing compounds in a solvent to obtain a dispersion system;

[0010] (2) The dispersion system obtained in step (1) is mixed with an organic solvent and a binder to obtain a precursor;

[0011] (3) The precursor is brought into contact with the support and then heat-treated to obtain a molybdenum-based composite oxide catalyst.

[0012] Wherein, X is selected from one or more of bismuth, niobium, indium, and antimony; A is selected from one or more of potassium, rubidium, and cesium; B is selected from boron and / or phosphorus; and C is selected from iron and / or cobalt.

[0013] In the dispersion system, the molar amounts of vanadium, X, A, B, and C relative to 1 mol of molybdenum are 0.1-1.5 mol, 0.001-0.025 mol, 0.001-0.015 mol, 0.001-0.015 mol, and 0.002-0.025 mol, respectively.

[0014] A third aspect of the present invention provides a molybdenum-based composite oxide catalyst prepared by the method described in the second aspect.

[0015] The fourth aspect of this invention provides an application of the molybdenum-based composite oxide catalyst described in the first or third aspect in the field of pyruvate preparation technology.

[0016] The fifth aspect of this invention provides a method for preparing pyruvic acid from lactic acid, the method comprising the following steps:

[0017] Under the reaction conditions for preparing pyruvate from lactic acid, lactic acid, an oxidant and a catalyst are contacted, wherein the catalyst is the molybdenum-based composite oxide catalyst described in the first or third aspect.

[0018] Through the above technical solution, the present invention has the following advantages:

[0019] (1) This invention uses molybdenum, vanadium, X, A, B, and C in specific proportions as active components to modify a molybdenum-based composite oxide catalyst. Under the combined effect of the above-mentioned elements, the molybdenum-based composite oxide catalyst achieves excellent catalytic performance, with a lactic acid conversion rate of up to 97.0%, a pyruvate selectivity of up to 80.2%, and a pyruvate yield of up to 77.1%.

[0020] (2) In a preferred embodiment, the present invention uses Fe and Co elements in a specific ratio. Under the combined effect of the two, the lactic acid conversion rate of the molybdenum-based composite oxide catalyst is further improved.

[0021] (3) In a preferred embodiment, the present invention modifies the molybdenum-based composite oxide catalyst by adding niobium and cesium, thereby improving the selectivity of the molybdenum-based composite oxide catalyst.

[0022] (4) Under the combined action of elements such as molybdenum, vanadium, niobium, cesium, phosphorus, iron, and cobalt, the catalytic performance of molybdenum-based composite oxide catalysts can be greatly improved, giving them better lactic acid conversion, pyruvate selectivity, and pyruvate yield.

[0023] (5) The catalyst described in this invention can be used to catalyze the oxidative dehydrogenation of lactic acid. The reaction is simple to operate and suitable for large-scale production.

[0024] (6) The present invention improves the catalytic performance of the catalyst by adding a binder to the catalytic active material, so that the active components are better loaded on the surface of the support and are not easy to fall off.

[0025] The catalyst prepared using the method of this invention can improve the lactic acid conversion rate by up to 14.8%, the pyruvate selectivity by up to 14.1%, and the pyruvate yield by up to 22.2% compared with the comparative example. Furthermore, this molybdenum-based composite oxide catalyst has a long service life, demonstrating promising industrial application value. Detailed Implementation

[0026] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and 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.

[0027] To achieve the above objectives, a first aspect of the present invention provides a molybdenum-based composite oxide catalyst, wherein the molybdenum-based composite oxide catalyst comprises a support and a catalyst of the general formula Mo1V. a Xb A c B d C e O x The active components;

[0028] Wherein, X is selected from one or more of bismuth, niobium, indium, and antimony; A is selected from one or more of potassium, rubidium, and cesium; B is selected from boron and / or phosphorus; and C is selected from iron and / or cobalt.

[0029] a, b, c, d, e, and x represent the atomic proportions of the corresponding elements, where a = 0.1-1.5, b = 0.001-0.025, c = 0.001-0.015, d = 0.001-0.015, e = 0.002-0.025, and x is the number of oxygen atoms required in the active component to satisfy the valence equilibrium requirements of other non-oxygen elements.

[0030] According to a preferred embodiment of the present invention, X is selected from one or more of bismuth, niobium, and antimony; more preferably, X includes niobium. Using X within the aforementioned more preferred range allows the catalyst to exhibit superior catalytic performance.

[0031] According to a preferred embodiment of the present invention, A is rubidium and / or cesium, more preferably cesium.

[0032] According to a preferred embodiment of the present invention, B is phosphorus.

[0033] According to a preferred embodiment of the present invention, C is iron and cobalt, more preferably, the molar ratio of iron to cobalt is 0.8-1.2:1. Using C within the aforementioned more preferred range allows the catalyst to have a better synergistic effect, resulting in higher lactic acid conversion, pyruvate selectivity, and pyruvate yield.

[0034] According to a preferred embodiment of the present invention, a = 0.3-1.2, for example, it can be a specific value or a range between two such as 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2, etc.

[0035] According to a preferred embodiment of the present invention, b = 0.01-0.02, for example, it can be a specific value or a range between the two, such as 0.01, 0.012, 0.014, 0.016, 0.018, 0.02.

[0036] According to a preferred embodiment of the present invention, c = 0.005-0.01, for example, it can be a specific value or a range between the two, such as 0.005, 0.006, 0.007, 0.008, 0.009, 0.01.

[0037] According to a preferred embodiment of the present invention, d = 0.005-0.01, for example, it can be a specific value or a range between the two, such as 0.005, 0.006, 0.007, 0.008, 0.009, 0.01.

[0038] According to a preferred embodiment of the present invention, e = 0.002-0.01, for example, it can be a specific value or a range between the two, such as 0.002, 0.004, 0.006, 0.008, 0.01.

[0039] According to a preferred embodiment of the present invention, the carrier is an inert carrier, more preferably an inorganic material, and even more preferably one or more of alumina, silicon carbide, magnesium silicate, aluminum silicate, quartz, ceramics and magnesium oxide.

[0040] According to a preferred embodiment of the present invention, magnesium silicate is sintered talc.

[0041] According to a preferred embodiment of the present invention, the thermal conductivity of the carrier is 10-100 W / (m·K), for example, it can be a specific thermal conductivity or a range between the two, such as 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 W / (m·K).

[0042] In this invention, there are no particular limitations on the shape of the carrier, as long as it can achieve the loading of the active component. Those skilled in the art can choose according to the actual situation. For example, the carrier can be a hollow cylinder, a cylindrical shape, a sphere, a pellet shape, a spiral shape, or a toothed sphere. Preferably, the carrier is a hollow cylinder.

[0043] In this invention, there are no particular limitations on the size of the carrier, and those skilled in the art can choose according to the actual situation. For example, when the carrier is a hollow cylinder, its outer diameter is 3-8 mm, its length is 3-8 mm, and its wall thickness is 1-2 mm.

[0044] According to a preferred embodiment of the present invention, based on the total mass of the molybdenum-based composite oxide catalyst, the content of the active component, calculated as oxide, is 10-25 wt%, for example, it can be a specific content or a range between the two, such as 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25; preferably, the content of the active component is 15-20 wt%.

[0045] In this invention, the active components are analyzed by weight composition analysis using X-ray fluorescence spectrometry (XRF).

[0046] In this invention, unless otherwise specified, percentage content refers to mass percentage content.

[0047] A second aspect of this invention provides a method for preparing a molybdenum-based composite oxide catalyst, the method comprising the following steps:

[0048] (1) Dissolve molybdenum-containing compounds, vanadium-containing compounds, X-containing compounds, A-containing compounds, B-containing compounds and C-containing compounds in a solvent to obtain a dispersion system;

[0049] (2) The dispersion system obtained in step (1) is mixed with an organic solvent and a binder to obtain a precursor;

[0050] (3) The precursor is brought into contact with the support and then heat-treated to obtain a molybdenum-based composite oxide catalyst.

[0051] Wherein, X is selected from one or more of bismuth, niobium, indium, and antimony; A is selected from one or more of potassium, rubidium, and cesium; B is selected from boron and / or phosphorus; and C is selected from iron and / or cobalt.

[0052] In the dispersion system, the molar amounts of vanadium, X, A, B, and C relative to 1 mol of molybdenum are 0.1-1.5 mol, 0.001-0.025 mol, 0.001-0.015 mol, 0.001-0.015 mol, and 0.002-0.025 mol, respectively.

[0053] According to a preferred embodiment of the present invention, X is selected from one or more of bismuth, niobium, and antimony; more preferably, X includes niobium. Using X within the aforementioned more preferred range allows the prepared catalyst to exhibit superior catalytic performance.

[0054] According to a preferred embodiment of the present invention, A is rubidium and / or cesium, more preferably cesium.

[0055] According to a preferred embodiment of the present invention, B is phosphorus.

[0056] According to a preferred embodiment of the present invention, C is iron and cobalt, more preferably, the molar ratio of iron to cobalt is 0.8-1.2:1. Using C within the aforementioned more preferred range allows the prepared catalyst to have better synergistic effects, resulting in higher lactic acid conversion, pyruvate selectivity, and pyruvate yield.

[0057] According to a preferred embodiment of the present invention, in the dispersion system, the molar amount of vanadium relative to 1 mol of molybdenum is 0.3-1.2 mol, for example, it can be a specific molar number or a range between the two, such as 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2 mol.

[0058] According to a preferred embodiment of the present invention, in the dispersion system, the molar amount of X relative to 1 mol of molybdenum is 0.01-0.02 mol, for example, it can be a specific number of moles such as 0.01, 0.012, 0.014, 0.016, 0.018, 0.02 mol or a range between the two.

[0059] According to a preferred embodiment of the present invention, in the dispersion system, the molar amount of A relative to 1 mol of molybdenum is 0.005-0.01 mol, for example, it can be a specific number of moles such as 0.005, 0.006, 0.007, 0.008, 0.009, 0.01 mol or a range between the two.

[0060] According to a preferred embodiment of the present invention, in the dispersion system, the molar amount of B relative to 1 mol of molybdenum is 0.005-0.01 mol, for example, it can be a specific number of moles such as 0.005, 0.006, 0.007, 0.008, 0.009, 0.01 mol or a range between the two.

[0061] According to a preferred embodiment of the present invention, in the dispersion system, the molar amount of C relative to 1 mol of molybdenum is 0.002-0.01 mol, for example, it can be a specific molar number or a range between 0.002, 0.004, 0.006, 0.008, 0.01 mol, etc.

[0062] In this invention, there are no particular restrictions on the types of molybdenum-containing compounds, as long as molybdenum can be provided. Those skilled in the art can select according to actual needs. For example, the molybdenum-containing compound is selected from one or more of ammonium molybdate, molybdenum trioxide, and sodium molybdate.

[0063] In this invention, there are no particular restrictions on the types of vanadium-containing compounds, as long as vanadium can be provided. Those skilled in the art can select according to actual needs. For example, the vanadium-containing compound is selected from one or more of ammonium metavanadate, vanadium pentoxide, vanadium trichloride, and sodium vanadate.

[0064] In this invention, there are no particular restrictions on the types of compounds containing X, as long as element X can be provided. Those skilled in the art can select according to actual needs. For example, the compound containing X is selected from one or more of oxides, ammonium salts, nitrates, carbonates, bicarbonates, sulfates, halides, oxalates, phosphates, hydrogen phosphates, and complexes of X; preferably, the complex of X is an acetylacetone complex.

[0065] In this invention, there are no particular restrictions on the types of compounds containing A, as long as element A can be provided. Those skilled in the art can select according to actual needs. For example, the compound containing A is selected from one or more of oxides, ammonium salts, nitrates, carbonates, bicarbonates, sulfates, halides, oxalates, phosphates, hydrogen phosphates, and complexes of A; preferably, the complex of A is an acetylacetone complex.

[0066] In this invention, there are no particular restrictions on the types of compounds containing carbon (C), as long as carbon (C) can be provided. Those skilled in the art can select according to actual needs. For example, the C-containing compound is selected from one or more of oxides, ammonium salts, nitrates, carbonates, bicarbonates, sulfates, halides, oxalates, phosphates, hydrogen phosphates, and complexes of C; preferably, the C complex is an acetylacetone complex.

[0067] In this invention, there are no particular restrictions on the types of compounds containing B, as long as element B can be provided. Those skilled in the art can select according to actual needs. For example, the compounds containing B are selected from one or more of phosphorus pentoxide, phosphoric acid, hydrogen phosphate, dihydrogen phosphate, phosphate, boric acid, borate, and trimethyl borate.

[0068] According to a preferred embodiment of the present invention, the solvent is water and / or a dilute acid solution.

[0069] According to a preferred embodiment of the present invention, the dilute acid solution is selected from one or more of dilute nitric acid, dilute hydrochloric acid, dilute oxalic acid, dilute acetic acid, and dilute sulfuric acid.

[0070] In this invention, the solvents used to dissolve molybdenum-containing compounds, vanadium-containing compounds, compounds containing X, compounds containing A, compounds containing B, and compounds containing C can be the same or different.

[0071] In this invention, molybdenum-containing compounds, vanadium-containing compounds, X-containing compounds, A-containing compounds, B-containing compounds, and C-containing compounds can be dissolved in the same solvent to obtain a dispersion system, or they can be dissolved in different solvents (of the same or different types) and then the resulting solutions are mixed to obtain a dispersion system.

[0072] In this invention, if one or more of the following compounds are dissolved in the same solvent: molybdenum-containing compound, vanadium-containing compound, X-containing compound, A-containing compound, B-containing compound, and C-containing compound, there is no particular limitation on the order of dissolution. The materials can be dissolved together or in sequence.

[0073] In this invention, there are no particular limitations on the concentration of the dilute acid solution, as long as it can dissolve the molybdenum-containing compound, vanadium-containing compound, compound X, compound A, compound B, and compound C. Those skilled in the art can select the appropriate concentration based on actual needs. For example, the mass fraction of the dilute acid solution is less than 15%, more preferably 1-10%.

[0074] According to a preferred embodiment of the present invention, the organic solvent is selected from alcohols or organic solvents containing hydroxyl groups, preferably one or more of monohydric alcohols, polyhydric alcohols, water-soluble ethers, and water-soluble amides, and more preferably one or more of methanol, ethanol, tetrahydrofuran, ethylene glycol dimethyl ether, formamide, N,N-dimethylformamide, pyrrolidone, and N-methylpyrrolidone.

[0075] In this invention, there are no particular restrictions on the form of the binder. Those skilled in the art can choose according to actual needs. For example, it can be an aqueous dispersion.

[0076] According to a preferred embodiment of the present invention, the binder comprises cellulose and its derivatives and / or copolymerized vinyl acetate. Using a binder within the above-mentioned range allows the active component to be better loaded onto the support surface and less prone to detachment, thereby more effectively improving the catalytic performance of the catalyst.

[0077] According to a preferred embodiment of the present invention, the cellulose and its derivatives are selected from one or more of cellulose ethers, anionic cellulose derivatives and nonionic cellulose derivatives; more preferably, the cellulose and its derivatives are selected from one or more of methylcellulose, ethylcellulose, sodium carboxymethylcellulose, cellulose acetate, hydroxyethylcellulose, hydroxypropylcellulose and hydroxypropylmethylcellulose.

[0078] According to a preferred embodiment of the present invention, the copolymerized vinyl acetate is selected from one or more of vinyl acetate-vinyl laurate, vinyl acetate-acrylate, vinyl acetate-ethylene, and vinyl acetate-styrene.

[0079] According to a preferred embodiment of the present invention, the precursor is a solution or suspension, preferably a suspension.

[0080] According to a preferred embodiment of the present invention, the viscosity of the precursor is 5-30 mPa·s, for example, it can be a specific viscosity such as 5, 10, 15, 20, 25, 30 mPa·s or a range between the two. This preferred embodiment is more conducive to the uniform loading of the catalyst active component onto the support surface; if the viscosity is too high, the active component cannot be well dispersed, and if the viscosity is too low, the active component cannot be well loaded onto the support surface.

[0081] According to a preferred embodiment of the present invention, the carrier is an inert carrier, more preferably an inorganic material, and even more preferably one or more of alumina, silicon carbide, magnesium silicate, aluminum silicate, quartz, ceramics and magnesium oxide.

[0082] According to a preferred embodiment of the present invention, magnesium silicate is sintered talc.

[0083] According to a preferred embodiment of the present invention, the thermal conductivity of the carrier is 10-100 W / (m·K), for example, it can be a specific thermal conductivity or a range between the two, such as 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 W / (m·K).

[0084] In this invention, there are no particular limitations on the shape of the carrier, and those skilled in the art can choose according to the actual situation. For example, the carrier can be a hollow cylinder, a cylindrical shape, a sphere, a pellet shape, a spiral shape, or a toothed sphere. Preferably, the carrier is a hollow cylinder.

[0085] In this invention, there are no particular limitations on the size of the carrier, and those skilled in the art can choose according to the actual situation. For example, when the carrier is a hollow cylinder, its outer diameter is 3-8 mm, its length is 3-8 mm, and its wall thickness is 1-2 mm.

[0086] According to a preferred embodiment of the present invention, when the precursor comes into contact with the carrier, the temperature of the carrier is 250-300°C, preferably 250-280°C.

[0087] In this invention, the range of contact methods is relatively wide, as long as sufficient contact can be achieved. Those skilled in the art can choose according to actual needs. For example, the contact method can be one or more of rinsing, spraying, and immersion, with spraying being preferred.

[0088] According to a preferred embodiment of the present invention, the precursor and the carrier are in contact in an air atmosphere, which may include a flowing atmosphere or a stationary atmosphere.

[0089] According to a preferred embodiment of the present invention, the heat treatment includes calcination; preferably, the heat treatment includes drying and calcination.

[0090] In this invention, the range of drying temperature and drying time is relatively wide, as long as drying can be achieved. Those skilled in the art can make the selection according to actual needs. For example, the drying temperature can be 100-140℃; the drying time can be 8-12 hours, or drying can be stopped after the mass of the dried material has reached a constant level.

[0091] In this invention, the range of selection for calcination temperature and calcination time is relatively wide, as long as it can achieve the conversion of the compound containing the active component into an oxide. Those skilled in the art can select according to actual needs. Preferably, the calcination temperature is 300-500℃ and the calcination time is 3-5 hours.

[0092] According to a preferred embodiment of the present invention, based on the total mass of the prepared molybdenum-based composite oxide catalyst, the content of the active component, calculated as oxide, is 10-25 wt%, for example, it can be a specific content or a range between the two, such as 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25; preferably, the content of the active component is 15-20 wt%.

[0093] A third aspect of the present invention provides a molybdenum-based composite oxide catalyst prepared by the method described in the second aspect.

[0094] The fourth aspect of this invention provides an application of the molybdenum-based composite oxide catalyst described in the first or third aspect in the field of pyruvate preparation technology.

[0095] The fifth aspect of this invention provides a method for preparing pyruvic acid from lactic acid, the method comprising the following steps:

[0096] Under the reaction conditions for preparing pyruvate from lactic acid, lactic acid, an oxidant and a catalyst are contacted, wherein the catalyst is the molybdenum-based composite oxide catalyst described in the first or third aspect.

[0097] According to a preferred embodiment of the present invention, the temperature for the reaction of lactic acid to pyruvic acid is 150-300°C, preferably 200-250°C.

[0098] According to a preferred embodiment of the present invention, the oxidant includes oxygen; more preferably, the oxygen content is 10 mol% or more; and even more preferably, the oxidant is air.

[0099] According to a preferred embodiment of the present invention, the molar ratio of lactic acid to oxidant (calculated as oxygen) is 1:15-25.

[0100] According to a preferred embodiment of the present invention, the reaction for preparing pyruvate from lactic acid is carried out in the presence of water.

[0101] According to a preferred embodiment of the present invention, the molar ratio of lactic acid to water is 1:1-8.

[0102] According to a preferred embodiment of the present invention, the mass hourly space velocity (MSV) of the gas present in the reaction of lactic acid to pyruvic acid is 500-1500 h⁻¹. -1 .

[0103] In this invention, the formulas for calculating the lactic acid conversion rate, pyruvate yield, and pyruvate selectivity are as follows:

[0104] Lactic acid conversion rate = (1 - Amount of lactic acid in the mixed gas after reaction / Amount of lactic acid in the mixed gas before reaction) × 100%

[0105] Pyruvate selectivity = Amount of pyruvate produced per unit time / Amount of lactic acid in the initial gas mixture × 100%

[0106] Pyruvate yield = Lactic acid conversion rate × Pyruvate selectivity × 100%

[0107] The present invention will be described in detail below through examples. Unless otherwise specified, all chemical reagents used in the following examples are commercially available products without further processing. Specifically, the ferric nitrate is ferric nitrate(III) nonahydrate; vinyl acetate-vinyl laurate is a commercially available product from Shanghai Tengyu New Material Technology Co., Ltd., with a solid content of 45-50%, and is a superior grade product; vinyl acetate-acrylate is a commercially available product from Weifang Jintai Material Factory, model RG-CV2020.

[0108] In the following embodiments, the backmixing reactor refers to an instrument capable of high-speed mixing and backmixing of a dispersion system, preferably a series of commercially available colloid mills.

[0109] In the following test examples, a fixed-bed reactor was used, with an inner diameter of 2.5 cm, a catalyst bed of approximately 30 cm, and a loading of 120 mL. The highest temperature point in the catalyst bed during the reaction was called the catalyst reaction temperature, which was measured using a thermocouple.

[0110] Example 1

[0111] (1) At room temperature, weigh 10.77g ammonium heptamolybdate, 0.66g niobate oxalate and 7.2g oxalic acid and dissolve them in 25mL of deionized water and stir until dissolved to obtain solutions 1, 2 and 3.

[0112] (2) Weigh 3.64g of ammonium metavanadate and dissolve it in solution 3 to obtain solution 4.

[0113] (3) Add solutions 1 and 2 to solution 4 in sequence while stirring to obtain solution 5.

[0114] (4) Weigh 0.25g trisodium phosphate, 0.053g cobalt nitrate and 0.063g rubidium nitrate and add them step by step to 100mL of deionized water at 50℃ to obtain dispersion system 1.

[0115] (5) After the solution 5 has reacted for half an hour, the solution 5 and the dispersion system 1 are simultaneously and quickly poured into the back-mixing reactor. After high-speed mixing for a certain period of time, the dispersion system 2 is obtained.

[0116] (6) Dispersion system 2, 15 mL of formamide, and 5 g of aqueous dispersion were simultaneously and rapidly poured into a colloid mill. The solid content of sodium carboxymethyl cellulose in the aqueous dispersion was 5%. The mixture was emulsified under high-speed shearing and backmixing conditions to obtain a uniform suspension. The backmixing time was 0.5 hours, and the viscosity of the suspension was controlled at 10 mPa·s. (The viscosity of the spraying liquid was measured using a viscometer.)

[0117] (7) The suspension obtained in step (6) is transferred into the feed tank of the spraying equipment feeding system and stirred.

[0118] (8) Place 50g of a hollow cylindrical carrier of silicon carbide with an outer diameter of 5mm, a length of 3mm and a wall thickness of 1.5mm in a stainless steel drum that can rotate and be heated. The drum speed is 15r / min.

[0119] (9) When the surface temperature of the carrier reaches 280℃, the suspension under stirring is sprayed onto the carrier surface using a pump at a spraying speed of 20mL / min. After spraying, the powder is dried until the mass is constant. Finally, the dried powder is calcined at 400℃ for 4 hours in an air stream to obtain catalyst S1. The composition of the catalyst is shown in Table 1.

[0120] Examples 2-9

[0121] The preparation steps are the same as in Example 1, except that the types and amounts of compounds containing molybdenum, vanadium, X, A, B, and C, the types and amounts of organic solvents and binders, and the amount of oxalic acid are shown in Tables 2-4.

[0122] In step (6), the backmixing time and the viscosity of the suspension are shown in Table 5.

[0123] Catalysts S2-S9 were obtained. The composition of the catalysts is shown in Table 1.

[0124] Comparative Examples 1 and 2

[0125] The preparation steps are the same as in Example 1, except that the types and amounts of compounds containing molybdenum, vanadium, X, A, B, and C, the types and amounts of organic solvents and binders, and the amount of oxalic acid are shown in Tables 2-4.

[0126] In step (6), the backmixing time and the viscosity of the suspension are shown in Table 5.

[0127] Catalysts D1 and D2 were obtained. The composition of the catalysts is shown in Table 1.

[0128] Table 1

[0129]

[0130]

[0131] Table 2

[0132]

[0133] Table 3

[0134]

[0135]

[0136] Table 4

[0137]

[0138] Table 5

[0139]

[0140]

[0141] Test case

[0142] Take 50g of catalysts S1-S9 and D1-D2 respectively and place them in a pilot reactor. The reaction temperature is 200℃. After maintaining this temperature for 5-30 minutes, the reaction gas is introduced into the fixed-bed reactor at a gas hourly space velocity of 800h⁻¹. -1 The volume ratio of lactic acid, water, and air in the gas mixture was 1:2.0:15.4. The gas obtained from the reaction was analyzed by gas chromatography, and the performance evaluation data are shown in Table 6.

[0143] Test comparison

[0144] Take 50g of catalyst D1 and place it in a small-scale reactor. Other test procedures are the same as in the test example.

[0145] The difference lies in the reaction temperature: 400℃, and the volume ratio of lactic acid, water, and air: 1:2.0:15.4. The gas obtained from the reaction was analyzed using gas chromatography, and the performance evaluation data are shown in Table 6.

[0146] Table 6

[0147]

[0148]

[0149] As can be seen from the table, the supported molybdenum-based composite oxide catalyst exhibits superior and unique catalytic performance in the catalytic dehydrogenation of lactic acid to pyruvate, and improves the thermal stability of the catalyst. The addition of Mo, V, Nb, and auxiliary metals gives the catalyst better oxidative dehydrogenation activity and improves the conversion rate of lactic acid and the selectivity of the oxidative dehydrogenation reaction.

[0150] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A molybdenum-based composite oxide catalyst, characterized in that, The molybdenum-based composite oxide catalyst contains a support and a catalyst with the general formula Mo1V. a X b A c B d C e O x The active components; Wherein, X is selected from one or more of bismuth, niobium, indium, and antimony; A is selected from one or more of potassium, rubidium, and cesium; B is selected from boron and / or phosphorus; and C is selected from iron and / or cobalt. a, b, c, d, e, and x represent the atomic proportions of the corresponding elements, where a = 0.1-1.5, b = 0.001-0.025, c = 0.001-0.015, d = 0.001-0.015, e = 0.002-0.025, and x is the number of oxygen atoms required in the active component to satisfy the valence equilibrium requirements of other non-oxygen elements.

2. The molybdenum-based composite oxide catalyst according to claim 1, wherein, X is selected from one or more of bismuth, niobium and antimony, more preferably, X includes niobium; Preferably, A is rubidium and / or cesium, more preferably cesium; Preferably, B is phosphorus; Preferably, C is iron and cobalt; more preferably, the molar ratio of iron to cobalt is 0.8-1.2:

1. Preferably, a = 0.3-1.2; Preferably, b = 0.01-0.02; Preferably, c = 0.005-0.01; Preferably, d = 0.005-0.01; Preferably, e = 0.002-0.

01.

3. The molybdenum-based composite oxide catalyst according to claim 1 or 2, wherein, The carrier is an inert carrier, more preferably an inorganic material, and even more preferably one or more of alumina, silicon carbide, magnesium silicate, aluminum silicate, quartz, ceramics and magnesium oxide; Preferably, the thermal conductivity of the carrier is 10-100 W / (m·K); Preferably, the carrier is a hollow cylinder, a cylindrical shape, a sphere, a pellet shape, a spiral shape, or a toothed sphere; more preferably, the carrier is a hollow cylinder. Preferably, the content of the active component, calculated as oxide, is 10-25 wt% based on the total mass of the molybdenum-based composite oxide catalyst, and more preferably 15-20 wt%.

4. A method for preparing a molybdenum-based composite oxide catalyst, the method comprising the following steps: (1) Dissolve molybdenum-containing compounds, vanadium-containing compounds, X-containing compounds, A-containing compounds, B-containing compounds and C-containing compounds in a solvent to obtain a dispersion system; (2) The dispersion system obtained in step (1) is mixed with an organic solvent and a binder to obtain a precursor; (3) The precursor is brought into contact with the support and then heat-treated to obtain a molybdenum-based composite oxide catalyst. Wherein, X is selected from one or more of bismuth, niobium, indium, and antimony; A is selected from one or more of potassium, rubidium, and cesium; B is selected from boron and / or phosphorus; and C is selected from iron and / or cobalt. In the dispersion system, the molar amounts of vanadium, X, A, B, and C relative to 1 mol of molybdenum are 0.1-1.5 mol, 0.001-0.025 mol, 0.001-0.015 mol, 0.001-0.015 mol, and 0.002-0.025 mol, respectively.

5. The method for preparing the molybdenum-based composite oxide catalyst according to claim 4, wherein, X is selected from one or more of bismuth, niobium and antimony, more preferably, X includes niobium; Preferably, A is rubidium and / or cesium, more preferably cesium; Preferably, B is phosphorus; Preferably, C is iron and cobalt; more preferably, the molar ratio of iron to cobalt is 0.8-1.2:

1. Preferably, in the dispersion system, the molar amount of vanadium relative to 1 mol of molybdenum is 0.3-1.2 mol; Preferably, in the dispersion system, the molar amount of X relative to 1 mol of molybdenum is 0.01-0.02 mol; Preferably, in the dispersion system, the molar amount of A relative to 1 mol of molybdenum is 0.005-0.01 mol; Preferably, in the dispersion system, the molar amount of B relative to 1 mol of molybdenum is 0.005-0.01 mol; Preferably, in the dispersion system, the molar amount of C relative to 1 mol of molybdenum is 0.002-0.01 mol.

6. The method for preparing the molybdenum-based composite oxide catalyst according to claim 4 or 5, wherein, The molybdenum-containing compound is selected from one or more of ammonium molybdate, molybdenum trioxide, and sodium molybdate; Preferably, the vanadium-containing compound is selected from one or more of ammonium metavanadate, vanadium pentoxide, vanadium trichloride, and sodium vanadate; Preferably, the compound containing X is selected from one or more of the following: oxides, ammonium salts, nitrates, carbonates, bicarbonates, sulfates, halides, oxalates, phosphates, hydrogen phosphates, and complexes of X. Preferably, the complex of X is an acetylacetone complex; Preferably, the compound containing A is selected from one or more of oxides, ammonium salts, nitrates, carbonates, bicarbonates, sulfates, halides, oxalates, phosphates, hydrogen phosphates, and complexes of A; Preferably, the complex of A is an acetylacetone complex; Preferably, the C-containing compound is selected from one or more of C oxides, ammonium salts, nitrates, carbonates, bicarbonates, sulfates, halides, oxalates, phosphates, hydrogen phosphates, and complexes; Preferably, the complex of C is an acetylacetone complex; Preferably, the B-containing compound is selected from one or more of phosphorus pentoxide, phosphoric acid, hydrogen phosphate, dihydrogen phosphate, phosphate, boric acid, borate, and trimethyl borate; Preferably, the solvent is water and / or a dilute acid solution; Preferably, the mass fraction of the dilute acid solution is less than 15%, more preferably 1-10%; Preferably, the dilute acid solution is selected from one or more of dilute nitric acid, dilute hydrochloric acid, dilute oxalic acid, dilute acetic acid, and dilute sulfuric acid.

7. The method for preparing the molybdenum-based composite oxide catalyst according to any one of claims 4-6, wherein, The organic solvent is selected from alcohols or organic solvents containing hydroxyl groups, preferably one or more of monohydric alcohols, polyhydric alcohols, water-soluble ethers, and water-soluble amides, and more preferably one or more of methanol, ethanol, tetrahydrofuran, ethylene glycol dimethyl ether, formamide, N,N-dimethylformamide, pyrrolidone, and N-methylpyrrolidone. Preferably, the binder is an aqueous dispersion; Preferably, the binder comprises cellulose and its derivatives and / or copolymerized vinyl acetate; Preferably, the cellulose and its derivatives are selected from one or more of cellulose ethers, anionic cellulose derivatives and nonionic cellulose derivatives; more preferably, the cellulose and its derivatives are selected from one or more of methylcellulose, ethylcellulose, sodium carboxymethylcellulose, cellulose acetate, hydroxyethylcellulose, hydroxypropylcellulose and hydroxypropylmethylcellulose. Preferably, the copolymerized vinyl acetate is selected from one or more of vinyl acetate-vinyl laurate, vinyl acetate-acrylate, vinyl acetate-ethylene, and vinyl acetate-styrene; Preferably, the viscosity of the precursor is 5-30 mPa·s.

8. The method for preparing the molybdenum-based composite oxide catalyst according to any one of claims 4-7, wherein, The carrier is an inert carrier, more preferably an inorganic material, and even more preferably one or more of alumina, silicon carbide, magnesium silicate, aluminum silicate, quartz, ceramics and magnesium oxide; Preferably, the thermal conductivity of the carrier is 10-100 W / (m·K); Preferably, the carrier is a hollow cylinder, a cylindrical shape, a sphere, a pellet shape, a spiral shape, or a toothed sphere; more preferably, the carrier is a hollow cylinder. Preferably, the heat treatment includes calcination at a temperature of 300-500℃ for 3-5 hours. Preferably, based on the total mass of the molybdenum-based composite oxide catalyst, the total content of molybdenum, vanadium, X, A, B, and C, calculated as oxides, is 10-25 wt%, more preferably 15-20 wt%.

9. A molybdenum-based composite oxide catalyst, characterized in that, The molybdenum-based composite oxide catalyst is prepared by the method described in any one of claims 4-8.

10. The application of the molybdenum-based composite oxide catalyst according to any one of claims 1-3 and 9 in the field of pyruvate preparation technology.

11. A method for preparing pyruvic acid from lactic acid, the method comprising the following steps: Under the reaction conditions for preparing pyruvate from lactic acid, lactic acid, an oxidant and a catalyst are contacted, wherein the catalyst is the molybdenum-based composite oxide catalyst according to any one of claims 1-3 and 9.

12. The method according to claim 11, wherein, The temperature for the reaction of lactic acid to pyruvic acid is 150-300℃, preferably 200-250℃; Preferably, the oxidant includes oxygen; more preferably, the oxygen content is 10 mol% or more; even more preferably, the oxidant is air. Preferably, the molar ratio of lactic acid to oxidant (calculated as oxygen) is 1:15-25; Preferably, the reaction for preparing pyruvate from lactic acid is carried out in the presence of water; Preferably, the molar ratio of lactic acid to water is 1:1-8; Preferably, the mass hourly space velocity (MSV) of the gas present in the reaction of lactic acid to pyruvate is 500-1500 h⁻¹. -1 .

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