Cobalt-based catalyst and preparation method and application thereof
By using a cobalt-based catalyst, the Co-N-C composite structure is formed by mixing cobalt salt with organic nitrogen source and loading of porous support, which solves the problems of high cost and by-products in the synthesis of gluconate in the prior art, and achieves a highly efficient and low-cost catalytic effect.
Patent Information
- Application Number
- CN202411541947.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-31
- Publication Date
- 2025-02-25
AI Technical Summary
In the prior art, in the synthesis of gluconic acid and its salts, there are problems such as high production costs, difficulty in recycling precious metal catalysts, and the need to maintain high temperatures in the thermal catalytic reaction, resulting in the generation of by-products.
Using a cobalt-based catalyst, a Cobalt salt is mixed with an organic nitrogen source and dissolved, supported on a porous support, and then calcined under a nitrogen atmosphere to form a Co-N-C composite structure, thereby improving catalytic activity and cyclic stability.
It realizes efficient catalytic glucose oxidation to form gluconate at lower cost and mild conditions, reduces production costs and improves the cycle stability of the catalyst.
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of catalysts, and in particular to a cobalt-based catalyst and a preparation method and application thereof. Background Art
[0002] Glucose is a widely available, cheap and high value-added chemical. Converting glucose into gluconic acid and its salts can greatly increase the added value of glucose itself. Gluconic acid and its salts are important intermediates for chemical, pharmaceutical and food products. They can be used as complexing agents, degreasing agents for steel, aluminum and glass surfaces, detergent aids, food additives and nutritional supplements. Common gluconates include calcium gluconate, sodium gluconate and potassium gluconate.
[0003] The existing technologies for synthesizing gluconic acid and its salts mainly include thermal catalysis and biological fermentation. In industrial production, fungi and bacteria are often used for biological fermentation to produce gluconic acid and its salts. For example, some researchers have proposed a non-sterile Gluconobacter oxidans-improved fluidized bed reactor process for the continuous production of gluconic acid. However, the separation and purification of the products in the biological fermentation process are relatively difficult, which greatly affects the production efficiency and increases the production cost and energy consumption.
[0004] In terms of thermal catalysis, some scholars have used a catalyst of gold nanoparticles loaded on a titanium silicon metal carrier to generate sodium gluconate in an environment of 60°C, pH=9.5, and an oxygen flow rate of 39mL / min, or loaded gold on modified carbon nanotubes and reacted for 4 hours in an environment of 90°C and 1MPaO2 to obtain gluconic acid with a yield of 99.3%, which was then converted into gluconate in subsequent steps. However, the use of precious metal catalysts will lead to increased production costs, and the precious metals in the catalyst are difficult to recover after failure. In addition, the thermal catalytic reaction needs to be maintained at a relatively high temperature range, which easily leads to the generation of by-products. Therefore, it is urgent to provide a solution to improve the above problems. Summary of the invention
[0005] The purpose of the present invention is to provide a cobalt-based catalyst and a preparation method and application thereof.
[0006] In a first aspect, the present invention provides a method for preparing a cobalt-based catalyst, comprising the following steps:
[0007] The cobalt salt and the organic nitrogen source are mixed and dissolved to prepare a precursor solution;
[0008] The porous carrier is mixed and dispersed in the precursor solution, stirred and separated to obtain the precursor;
[0009] The precursor is calcined at 600-1000° C. in a nitrogen atmosphere, cooled, and then acid-washed to obtain a cobalt-based catalyst.
[0010] Optionally, when the cobalt salt is mixed and dissolved with the organic nitrogen source: the cobalt salt includes at least one of CoF2, CoCl2, CoBr2, CoI2, CoCO3, Co(NO3)2, CoSO4, and (CH3COO)2Co.
[0011] Optionally, when the cobalt salt and the organic nitrogen source are mixed and dissolved: the organic nitrogen source includes at least one of dimethylimidazole, 1,10-phenanthroline, triethylenediamine, pyridine, imidazole, and 2,2-bipyridine.
[0012] Optionally, when the cobalt salt and the organic nitrogen source are mixed and dissolved, the mass ratio of the cobalt salt to the organic nitrogen source is (0.6-0.8):1.
[0013] Optionally, when the cobalt salt and the organic nitrogen source are mixed and dissolved, the molar ratio of the cobalt element in the cobalt salt to the nitrogen element in the organic nitrogen source is 1:(2-5).
[0014] Optionally, when the cobalt salt and the organic nitrogen source are mixed and dissolved: the solvent used for the mixed dissolution includes at least one of methanol, ethanol, dimethylformamide, acetonitrile and toluene.
[0015] Optionally, when the porous carrier is mixed and dispersed in the precursor solution: the porous carrier includes at least one of g-C3N4, MgO, Mg(OH)2, and activated carbon.
[0016] Optionally, when the porous carrier is mixed and dispersed in the precursor solution, the mass ratio of the porous carrier to the cobalt salt is 1:(2-16).
[0017] Optionally, when the porous carrier is mixed and dispersed in the precursor solution: the solid-liquid ratio of the porous carrier to the precursor solution is 1: (2.5-6.25) g / mL.
[0018] Optionally, when the porous carrier is mixed and dispersed in the precursor solution, the mixed and dispersed process includes at least one of ultrasonic dispersion and stirring dispersion.
[0019] Optionally, when the porous carrier is mixed and dispersed in the precursor solution and stirred and separated to obtain the precursor: the reaction is stirred at 50-70°C.
[0020] Optionally, when the porous carrier is mixed and dispersed in the precursor solution, stirred and separated to obtain the precursor: stirring the reaction for 6-8 hours and then separating.
[0021] Optionally, when the porous carrier is mixed and dispersed in the precursor solution, stirred and separated to obtain the precursor: after separation, the precursor is dried at 50-70° C. to obtain the precursor.
[0022] Optionally, when the porous carrier is mixed and dispersed in the precursor solution, stirred and separated to obtain the precursor: after separation, the precursor is dried for 6-24 hours to obtain the precursor.
[0023] Optionally, when the porous carrier is mixed and dispersed in the precursor solution, stirred and separated to obtain the precursor: the separation includes at least one of centrifugal separation and suction filtration separation.
[0024] Optionally, when the precursor is calcined in a nitrogen atmosphere at 600-1000° C.: the precursor is calcined in a nitrogen atmosphere at 600-1000° C. for 0.5-1.5 h.
[0025] Optionally, when the precursor is calcined in a nitrogen atmosphere at 600-1000° C.: the precursor is heated to 600-1000° C. at a rate of 5-25° C. / min.
[0026] Optionally, when the precursor is calcined in a nitrogen atmosphere at 600-1000° C.: the precursor is calcined at a constant temperature at any temperature within the range of 600-1000° C.
[0027] In a second aspect, the present invention also provides a cobalt-based catalyst prepared by any of the above optional preparation methods.
[0028] Optionally, the loading amount of cobalt element in the cobalt-based catalyst is 2-5 wt.%.
[0029] Optionally, the cobalt-based catalyst has a Co-NC composite structure.
[0030] In a third aspect, the present invention also provides an application of a cobalt-based catalyst. DETAILED DESCRIPTION
[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with general skills in the field to which the present invention belongs.
[0032] The present invention provides a method for preparing a cobalt-based catalyst, comprising the following steps:
[0033] S1, mixing and dissolving a cobalt salt and an organic nitrogen source to prepare a precursor solution;
[0034] S2, mixing and dispersing the porous carrier in the precursor solution, stirring and separating to obtain a precursor;
[0035] S3, calcining the precursor at 600-1000° C. in a nitrogen atmosphere, cooling and acid washing to obtain a cobalt-based catalyst.
[0036] Specifically, the present invention mixes and dissolves the cobalt salt and the organic unit in step S1, which is conducive to the uniform dispersion of the cobalt salt and the organic nitrogen source in the precursor solution, thereby facilitating the uniform loading on the surface of the porous support in step S2, and then after calcination under a nitrogen atmosphere, a Co-NC composite structure can be formed on the porous support, which is conducive to improving the catalytic activity and cycle stability of the cobalt-based catalyst. Specifically, the present invention uses an impregnation method to load the cobalt salt and the nitrogen source on the porous support, and calcines under a nitrogen atmosphere and then cools to obtain a cobalt-based catalyst.
[0037] In some embodiments, when executing step S1, the cobalt salt used includes at least one of CoF2, CoCl2, CoBr2, CoI2, CoCO3, Co(NO3)2, CoSO4, and (CH3COO)2Co. In fact, the cobalt salt used must be able to be dissolved, and in order to reduce the preparation cost, a relatively cheap cobalt salt material can be selected.
[0038] In some embodiments, when performing step S1, the organic nitrogen source used includes at least one of dimethyl imidazole, 1,10-phenanthroline, triethylenediamine, pyridine, imidazole, and 2,2-bipyridine. In fact, when the organic nitrogen source is mixed with the cobalt salt and impregnated on the surface of the porous carrier, the organic nitrogen source can play a certain role in fixing the cobalt salt, thereby increasing the loading amount of the cobalt salt.
[0039] In some embodiments, when performing step S1, the mass ratio of the cobalt salt to the organic nitrogen source is (0.6-0.8):1. In fact, by adjusting the mass mixing ratio of the cobalt salt to the organic nitrogen source, the loading amount of cobalt and nitrogen on the surface of the porous carrier can be adjusted, thereby adjusting the catalytic activity of the cobalt-based catalyst finally obtained. Specifically, the molar ratio of the cobalt element in the cobalt salt to the nitrogen element in the organic nitrogen source is 1:(2-5).
[0040] In fact, when performing step S1, the solvent used for mixing and dissolving the cobalt salt and the organic nitrogen source includes at least one of methanol, ethanol, dimethylformamide, acetonitrile and toluene. Specifically, the solvent used for mixed dissolution can be an organic solvent commonly used in the art, which is necessary to be able to completely dissolve the cobalt salt and the organic nitrogen source without chemically reacting with the two.
[0041] In some embodiments, when performing step S2, the porous carrier used includes at least one of g-C3N4, MgO, Mg(OH)2, and activated carbon. In fact, the porous carrier has a high specific surface area, so that the cobalt salt and the organic nitrogen source can be fully loaded. Specifically, the mass ratio of the porous carrier to the cobalt salt is 1:(2-16).
[0042] In some embodiments, when performing step S2, the solid-liquid ratio of the porous carrier to the precursor solution is 1: (2.5-6.25) g / mL. In fact, by controlling the solid-liquid ratio of the porous carrier to the precursor solution, it can help the porous carrier to be fully mixed in the precursor solution. In addition, the porous carrier and the precursor solution can be ultrasonically mixed using an ultrasonic device, and the agglomeration and sedimentation of the porous carrier can be avoided by the ultrasonic cavitation effect. In some embodiments, the porous carrier and the precursor solution can also be dispersed by mechanical stirring and dispersion.
[0043] In some embodiments, when performing step S2, the porous carrier is mixed and dispersed in a precursor solution at 50-70° C. for stirring reaction. This is conducive to improving the surface activity of the porous carrier in the precursor solution, thereby promoting the loading of the cobalt salt and the organic nitrogen source on the surface of the porous carrier. Specifically, the porous carrier can be stirred in the precursor solution for 6-8 hours to promote the sufficient loading of the cobalt salt and the organic nitrogen source on the surface of the porous carrier.
[0044] In some embodiments, when performing step S2, after the porous carrier is stirred and reacted in the precursor solution and impregnated, the porous carrier after the impregnation treatment can be separated by centrifugation or suction filtration, and the separated solid is dried at 50-70° C. to constant weight to obtain a precursor. In addition, the solid can be controlled to be dried at 50-70° C. for 6-25 hours.
[0045] Specifically, when executing step S3, the precursor is heat-treated in a nitrogen atmosphere at 600-1000°C for 0.5-2h for calcination. In fact, by calcining the precursor in a nitrogen atmosphere, it is beneficial to convert the organic nitrogen source on the surface of the porous carrier into an NC structure, and promote the formation of Co-NC connection between NC and cobalt, thereby improving the load stability on the surface of the porous carrier. At the same time, sintering in a nitrogen atmosphere can effectively increase the nitrogen doping amount in the cobalt-based catalyst. In some embodiments, when executing step S3, the precursor is heated to 600-1000°C at a rate of 5-25°C / min, and is subjected to constant temperature treatment at any temperature value within 600-1000°C.
[0046] The present invention also provides a cobalt-based catalyst prepared by the preparation method in any of the above embodiments, wherein the loading amount of metallic cobalt is 2-5wt.%, and the cobalt-based catalyst has a Co-NC composite structure to improve the catalytic activity and performance stability of the cobalt-based catalyst.
[0047] The present invention also provides a catalytic synthesis method of gluconate, wherein gluconate is generated by oxidation reaction of glucose with oxygen under the catalytic action of a cobalt-based catalyst in an alkaline solvent environment.
[0048] In some embodiments, the mass ratio of glucose to the cobalt-based catalyst is (5-40):1, and the molar ratio of glucose to the metallic cobalt in the cobalt-based catalyst is (0.02-0.06):1, so that the metallic cobalt in the cobalt-based catalyst can catalyze the oxidation reaction of glucose, thereby improving the reaction efficiency and reaction effectiveness.
[0049] In some embodiments, the alkaline solute dissolved in the alkaline solvent environment includes one of sodium salt, potassium salt, and calcium salt. In fact, by adjusting the alkaline solute in the solvent environment, the type of gluconate generated can be adjusted. For example, if sodium salt is dissolved in the solvent environment, sodium gluconate can be generated. Specifically, the alkaline solute can be one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and calcium hydroxide.
[0050] In fact, the catalytic synthesis method of gluconate provided by the present invention comprises the following steps:
[0051] Y1. Mixing glucose, a cobalt-based catalyst and an alkali metal salt in a solvent environment to prepare a mixed solution;
[0052] Y2. Pass oxygen into the mixed solution, stir the mixture to react, and then separate and purify to obtain gluconate.
[0053] In some embodiments, when performing step Y1, glucose, a cobalt-based catalyst and an alkali metal salt may be mixed and dissolved in deionized water to prepare a mixed solution.
[0054] In some embodiments, when executing step Y2, the oxygen flow rate is 1-100 mL / min. In addition, oxygen is introduced into the mixed solution and stirred for reaction at 15-30°C. At the same time, the cobalt-based catalyst is recovered under reduced pressure during separation and purification, and the gluconate is obtained by crystallization and drying after reduced pressure concentration.
[0055] At the same time, the present invention also provides a catalytic synthesis method of gluconic acid, comprising: dissolving gluconic acid salt to prepare gluconic acid salt solution on the basis of the above preparation of gluconic acid salt, stirring the gluconic acid salt solution with a strong acid to separate a gluconic acid crude extract, and column purifying the gluconic acid crude extract to obtain gluconic acid. Specifically, the strong acid includes sulfuric acid.
[0056] Preparation Example 1
[0057] This preparation example 1 provides a method for preparing a cobalt-based catalyst, comprising the following steps:
[0058] S1. 0.125 g (0.5 mmol) (CH3COO)2Co·4H2O and 0.18 g (1 mmol) 1,10-phenanthroline were stirred and dissolved in 50 mL ethanol to prepare a precursor solution;
[0059] S2, adding 2 g of g-C3N4 (prepared by calcining urea in a muffle furnace) to the precursor solution, stirring and mixing in a 60°C water bath, and then centrifuging, and drying the separated solid in a 60°C vacuum drying oven for 12 h to obtain a yellow precursor;
[0060] S3. Under a nitrogen atmosphere, the precursor was placed in a crucible and heated from room temperature to 800°C at a rate of 25°C / min and kept at that temperature for 2h. Then, the precursor was cooled to room temperature and acid-washed to obtain a cobalt-based catalyst (Co-NC-800-N1).
[0061] Preparation Example 2
[0062] This Preparation Example 2 provides a preparation method for a cobalt-based catalyst, which is different from Preparation Example 1 in that in step S1, 0.065 g (0.5 mmol) of CoCl2 and 0.328 g (2 mmol) of dimethylimidazole are stirred and dissolved in 50 mL of dimethylformamide (DMF) to prepare a precursor solution; in step S3, a cobalt-based catalyst (Co-NC-800-N2) is prepared.
[0063] Preparation Example 3
[0064] This Preparation Example 3 provides a preparation method for a cobalt-based catalyst, which is different from Preparation Example 1 in that in step S1, 0.065 g (0.5 mmol) CoCl2 and 0.328 g (2 mmol) dimethylimidazole are stirred and dissolved in 50 mL of methanol to prepare a precursor solution; in step S3, a cobalt-based catalyst (Co-NC-800-N3) is prepared.
[0065] Preparation Example 4
[0066] This Preparation Example 4 provides a preparation method for a cobalt-based catalyst, which is different from Preparation Example 1 in that in step S1, 0.0775 g (0.5 mmol) of CoSO4 and 0.156 g (1 mmol) of 2,2-bipyridine are stirred and dissolved in 50 mL of dimethylformamide (DMF) to prepare a precursor solution; in step S3, a cobalt-based catalyst (Co-NC-800-N4) is prepared.
[0067] Preparation Example 5
[0068] This Preparation Example 5 provides a preparation method for a cobalt-based catalyst, which is different from Preparation Example 1 in that in step S1, 0.125 g (0.5 mmol) (CH3COO)2Co·4H2O and 0.328 g (2 mmol) dimethylimidazole are stirred and dissolved in 50 mL of isopropanol to prepare a precursor solution; in step S3, a cobalt-based catalyst (Co-NC-800-N5) is prepared.
[0069] Preparation Example 6
[0070] This Preparation Example 6 provides a preparation method for a cobalt-based catalyst, which is different from Preparation Example 1 in that in step S3, the temperature is raised to 700°C and kept for 2 hours, and then cooled to room temperature and acid-washed to obtain a cobalt-based catalyst (Co-NC-700-N1).
[0071] Example 1
[0072] This embodiment 1 provides a method for preparing calcium gluconate by oxidizing glucose, comprising the following steps:
[0073] Y1, 1 mmol of glucose, 0.0402 mmol of a cobalt-based catalyst (Preparation Example 1, based on the amount of cobalt substance), 10 mL of deionized water and 0.75 mmol of Ca(OH)2 were placed in a 25 mL reaction container and mixed to obtain a mixed solution;
[0074] Y2. Oxygen was introduced from the bottom of the mixed solution at a flow rate of 25 mL / min, and the mixed solution was stirred at a constant temperature of 25°C. After reacting for 6 hours, the filtrate and the cobalt-based catalyst were separated by suction filtration. After the filtrate was fixed to 25 mL, 1 mL of the filtrate was extracted for high performance liquid chromatography detection, and the yield of calcium gluconate was 95.3%. The remaining filtrate was concentrated under reduced pressure, crystallized and dried to obtain calcium gluconate.
[0075] Example 2
[0076] This embodiment 2 provides a method for preparing sodium gluconate by oxidizing glucose, comprising the following steps:
[0077] Y1, 1 mmol of glucose, 0.0402 mmol of a cobalt-based catalyst (Preparation Example 1, based on the amount of cobalt substance), 10 mL of deionized water and 1 mmol of Na2CO3 were placed in a 25 mL reaction container and mixed to obtain a mixed solution;
[0078] Y2. Oxygen is introduced from the bottom of the mixed liquid at a flow rate of 25 mL / min, and the mixed liquid is stirred at a constant temperature of 25°C. After reacting for 8 hours, the filtrate and the cobalt-based catalyst are separated by suction. After the filtrate is fixed to 25 mL, 1 mL of the filtrate is extracted for high performance liquid chromatography detection, and the yield of sodium gluconate is 97.0%. The remaining filtrate is concentrated under reduced pressure, crystallized and dried to obtain sodium gluconate and Na2CO3.
[0079] Example 3
[0080] This embodiment 3 provides a method for preparing potassium gluconate by oxidizing glucose, comprising the following steps:
[0081] Y1, 1 mmol of glucose, 0.0402 mmol of a cobalt-based catalyst (Preparation Example 1, based on the amount of cobalt substance), 10 mL of deionized water and 1 mmol of K2CO3 were placed in a 25 mL reaction container and mixed to obtain a mixed solution;
[0082] Y2. Oxygen is introduced from the bottom of the mixed liquid at a flow rate of 25 mL / min, and the mixed liquid is stirred at a constant temperature of 25°C. After reacting for 8 hours, the filtrate and the cobalt-based catalyst are separated by suction filtration. After the filtrate is fixed to 25 mL, 1 mL of the filtrate is extracted for high performance liquid chromatography detection, and the yield of potassium gluconate is 97.0%. The remaining filtrate is concentrated under reduced pressure, crystallized and dried to obtain potassium gluconate and K2CO3.
[0083] Example 4
[0084] This embodiment 4 provides a method for preparing calcium gluconate by oxidizing glucose, comprising the following steps:
[0085] Y1, 1 mmol of glucose, 0.0804 mmol of a cobalt-based catalyst (Preparation Example 1, based on the amount of cobalt substance), 10 mL of deionized water and 0.75 mmol of Ca(OH)2 were placed in a 25 mL reaction container and mixed to obtain a mixed solution;
[0086] Y2. Oxygen was introduced from the bottom of the mixed solution at a flow rate of 25 mL / min, and the mixed solution was stirred at a constant temperature of 25°C. After reacting for 4 hours, the filtrate and the cobalt-based catalyst were separated by suction filtration. After the filtrate was fixed to 25 mL, 1 mL of the filtrate was extracted for high performance liquid chromatography detection. The yield of calcium gluconate was 94.5%. The remaining filtrate was concentrated under reduced pressure, crystallized and dried to obtain calcium gluconate.
[0087] Example 5
[0088] This embodiment 5 provides a method for preparing calcium gluconate by oxidizing glucose, comprising the following steps:
[0089] Y1, 2 mmol glucose, 0.0804 mmol cobalt-based catalyst (Preparation Example 2, based on the amount of cobalt substance), 10 mL deionized water and 1.2 mmol Ca(OH)2 were placed in a 25 mL reaction container and mixed to obtain a mixed solution;
[0090] Y2. Oxygen was introduced from the bottom of the mixed solution at a flow rate of 25 mL / min, and the mixed solution was stirred at a constant temperature of 25°C. After reacting for 15 hours, the filtrate and the cobalt-based catalyst were separated by suction filtration. After the filtrate was fixed to 25 mL, 1 mL of the filtrate was extracted for high performance liquid chromatography detection, and the yield of calcium gluconate was 96.6%. The remaining filtrate was concentrated under reduced pressure, crystallized and dried to obtain calcium gluconate.
[0091] Example 6
[0092] This embodiment 6 provides a method for preparing calcium gluconate by oxidizing glucose, comprising the following steps:
[0093] Y1, 1 mmol of glucose, 0.0402 mmol of a cobalt-based catalyst (Preparation Example 3, based on the amount of cobalt substance), 5 mL of deionized water and 0.75 mmol of Ca(OH)2 were placed in a 25 mL reaction container and mixed to obtain a mixed solution;
[0094] Y2. Oxygen was introduced from the bottom of the mixed solution at a flow rate of 25 mL / min, and the mixed solution was stirred at a constant temperature of 25°C. After reacting for 16 hours, the filtrate and the cobalt-based catalyst were separated by suction filtration. After the filtrate was fixed to 25 mL, 1 mL of the filtrate was extracted for high performance liquid chromatography detection. The yield of calcium gluconate was 92.3%. The remaining filtrate was concentrated under reduced pressure, crystallized and dried to obtain calcium gluconate.
[0095] Example 7
[0096] This embodiment 7 provides a method for preparing calcium gluconate by oxidizing glucose, comprising the following steps:
[0097] Y1, 1 mmol of glucose, 0.0402 mmol of a cobalt-based catalyst (Preparation Example 1, based on the amount of cobalt substance), 10 mL of deionized water and 0.75 mmol of Ca(OH)2 were placed in a 25 mL reaction container and mixed to obtain a mixed solution;
[0098] Y2. Oxygen was introduced from the bottom of the mixed solution at a flow rate of 5 mL / min, and the mixed solution was stirred at a constant temperature of 25°C. After reacting for 10 hours, the filtrate and the cobalt-based catalyst were separated by filtration. After the filtrate was fixed to 25 mL, 1 mL of the filtrate was extracted for high performance liquid chromatography detection, and the yield of calcium gluconate was 94.2%. The remaining filtrate was concentrated under reduced pressure, crystallized and dried to obtain calcium gluconate.
[0099] Example 8
[0100] This embodiment 8 provides a method for preparing calcium gluconate by oxidizing glucose, comprising the following steps:
[0101] Y1, 1 mmol of glucose, 0.0201 mmol of a cobalt-based catalyst (Preparation Example 1, based on the amount of cobalt substance), 10 mL of deionized water and 0.75 mmol of Ca(OH)2 were placed in a 25 mL reaction container and mixed to obtain a mixed solution;
[0102] Y2. Oxygen was introduced from the bottom of the mixed solution at a flow rate of 25 mL / min, and the mixed solution was stirred at a constant temperature of 25°C. After reacting for 15 hours, the filtrate and the cobalt-based catalyst were separated by suction filtration. After the filtrate was fixed to 25 mL, 1 mL of the filtrate was extracted for high performance liquid chromatography detection, and the yield of calcium gluconate was 95.6%. The remaining filtrate was concentrated under reduced pressure, crystallized and dried to obtain calcium gluconate.
[0103] Example 9
[0104] This embodiment 9 provides a method for preparing calcium gluconate by oxidizing glucose, comprising the following steps:
[0105] Y1, 1 mmol of glucose, 0.0402 mmol of a cobalt-based catalyst (Preparation Example 4, based on the amount of cobalt substance), 10 mL of deionized water and 0.75 mmol of Ca(OH)2 were placed in a 25 mL reaction container and mixed to obtain a mixed solution;
[0106] Y2. Oxygen was introduced from the bottom of the mixed solution at a flow rate of 25 mL / min, and the mixed solution was stirred at a constant temperature of 25°C. After reacting for 12 hours, the filtrate and the cobalt-based catalyst were separated by suction filtration. After the filtrate was fixed to 25 mL, 1 mL of the filtrate was extracted for high performance liquid chromatography detection, and the yield of calcium gluconate was 94.1%. The remaining filtrate was concentrated under reduced pressure, crystallized and dried to obtain calcium gluconate.
[0107] Example 10
[0108] This embodiment 10 provides a method for preparing sodium gluconate by oxidizing glucose, comprising the following steps:
[0109] Y1, 1 mmol of glucose, 0.0402 mmol of a cobalt-based catalyst (Preparation Example 5, based on the amount of cobalt substance), 10 mL of deionized water and 1 mmol of Na2CO3 were placed in a 25 mL reaction container and mixed to obtain a mixed solution;
[0110] Y2. Oxygen is introduced from the bottom of the mixed liquid at a flow rate of 25 mL / min, and the mixed liquid is stirred at a constant temperature of 25°C. After reacting for 16 hours, the filtrate and the cobalt-based catalyst are separated by suction filtration. After the filtrate is fixed to 25 mL, 1 mL of the filtrate is extracted for high performance liquid chromatography detection, and the yield of sodium gluconate is 94.1%. The remaining filtrate is concentrated under reduced pressure, crystallized and dried to obtain sodium gluconate and Na2CO3.
[0111] Embodiment 11
[0112] This embodiment 11 provides a method for preparing sodium gluconate by oxidizing glucose, comprising the following steps:
[0113] Y1, 1 mmol of glucose, 0.0402 mmol of a cobalt-based catalyst (Preparation Example 6, based on the amount of cobalt substance), 10 mL of deionized water and 1 mmol of Na2CO3 were placed in a 25 mL reaction container and mixed to obtain a mixed solution;
[0114] Y2. Oxygen is introduced from the bottom of the mixed liquid at a flow rate of 25 mL / min, and the mixed liquid is stirred at a constant temperature of 25°C. After reacting for 12 hours, the filtrate and the cobalt-based catalyst are separated by suction filtration. After the filtrate is fixed to 25 mL, 1 mL of the filtrate is extracted for high performance liquid chromatography detection, and the yield of sodium gluconate is 95.1%. The remaining filtrate is concentrated under reduced pressure, crystallized and dried to obtain sodium gluconate and Na2CO3.
[0115] Example 12
[0116] This embodiment 12 provides a method for preparing potassium gluconate by oxidizing glucose, comprising the following steps:
[0117] Y1, 1 mmol of glucose, 0.064 mmol of a cobalt-based catalyst (Preparation Example 1, based on the amount of cobalt substance), 5 mL of deionized water and 1 mmol of K2CO3 were placed in a 25 mL reaction container and mixed to obtain a mixed solution;
[0118] Y2. Oxygen is introduced from the bottom of the mixed liquid at a flow rate of 40 mL / min, and the mixed liquid is stirred at a constant temperature of 25°C. After reacting for 7 hours, the filtrate and the cobalt-based catalyst are separated by suction filtration. After the filtrate is fixed to 25 mL, 1 mL of the filtrate is extracted for high performance liquid chromatography detection, and the yield of potassium gluconate is 94.1%. The remaining filtrate is concentrated under reduced pressure, crystallized and dried to obtain potassium gluconate and K2CO3.
[0119] Example 13
[0120] This embodiment 13 provides a method for preparing gluconic acid by oxidizing glucose, which further comprises the following steps based on embodiment 1:
[0121] Y3. Dissolve 0.05 mol (21.5 g) of calcium gluconate in 1 L of deionized water with stirring to prepare a calcium gluconate solution. Slowly add 1 mol (100 mL) of concentrated sulfuric acid to the calcium gluconate solution while stirring. Stir the mixture in a 60° C. water bath for 1.5 h, and filter while hot to obtain a crude gluconic acid extract.
[0122] Y4. The crude gluconic acid extract was passed through a weakly basic anion exchange resin D318 at a certain flow rate to obtain a pure gluconic acid solution. The calculated yield was 99%.
[0123] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.
Claims
1. A method for preparing a cobalt-based catalyst, characterized in that: The following steps are involved: The cobalt salt and the organic nitrogen source are mixed and dissolved to prepare a precursor solution; The porous carrier is mixed and dispersed in the precursor solution, stirred and separated to obtain the precursor; The precursor is calcined at 600-1000° C. in a nitrogen atmosphere, cooled, and then acid-washed to obtain a cobalt-based catalyst.
2. The preparation method according to claim 1, characterized in that: When the cobalt salt is mixed and dissolved with an organic nitrogen source: The cobalt salt includes at least one of CoF2, CoCl2, CoBr2, CoI2, CoCO3, Co(NO3)2, CoSO4, and (CH3COO)2Co; And / or, the organic nitrogen source includes at least one of dimethylimidazole, 1,10-phenanthroline, triethylenediamine, pyridine, imidazole, and 2,2-bipyridine; And / or, the mass ratio of the cobalt salt to the organic nitrogen source is (0.6-0.8):1; and / or, the molar ratio of the cobalt element in the cobalt salt to the nitrogen element in the organic nitrogen source is 1:(2-5); And / or, the solvent used in the mixed dissolution includes at least one of methanol, ethanol, dimethylformamide, acetonitrile and toluene.
3. The preparation method according to claim 1, characterized in that: When the porous support is mixed and dispersed in the precursor solution: The porous carrier includes at least one of g-C3N4, MgO, Mg(OH)2, and activated carbon; and / or, the mass ratio of the porous carrier to the cobalt salt is 1:(2-16); and / or, the solid-to-liquid ratio of the porous support to the precursor solution is 1:(2.5-6.25) g / mL; And / or, the mixing and dispersing comprises at least one of ultrasonic dispersing and stirring dispersing.
4. The preparation method according to claim 1, characterized in that: When the porous carrier is mixed and dispersed in the precursor solution and stirred and separated to obtain the precursor: Stir the reaction at 50-70°C; and / or, stirring the reaction for 6-8 hours and then separating; and / or, drying at 50-70° C. to obtain a precursor after separation; and / or, drying for 6-24 hours after separation to obtain a precursor; And / or, the separation includes at least one of centrifugal separation and suction filtration separation.
5. The preparation method according to claim 1, characterized in that: When the precursor is calcined at 600-1000℃ in a nitrogen atmosphere: The precursor is calcined at 600-1000°C in a nitrogen atmosphere for 0.5-2h; and / or, heating the precursor to 600-1000° C. at a rate of 5-25° C. / min; And / or, the precursor is calcined at any temperature within the range of 600-1000°C.
6. A cobalt-based catalyst prepared by the preparation method according to any one of claims 1 to 5.
7. The cobalt-based catalyst according to claim 6, characterized in that The loading amount of cobalt element in the cobalt-based catalyst is 2-5wt.%; and / or the cobalt-based catalyst has a Co-NC composite structure.
8. Use of a cobalt-based catalyst prepared by the preparation method according to any one of claims 1 to 5 or a cobalt-based catalyst according to any one of claims 6 to 7.