CN114031493B - Method for preparing high-purity glycolic acid by selective oxidation of ethylene glycol - Google Patents
Method for preparing high-purity glycolic acid by selective oxidation of ethylene glycol Download PDFInfo
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- AEMRFAOFKBGASW-UHFFFAOYSA-N Glycolic acid Chemical compound OCC(O)=O AEMRFAOFKBGASW-UHFFFAOYSA-N 0.000 title claims abstract description 117
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 title claims abstract description 94
- 238000000034 method Methods 0.000 title claims abstract description 33
- 238000007254 oxidation reaction Methods 0.000 title claims abstract description 13
- 230000003647 oxidation Effects 0.000 title claims abstract description 12
- 239000003054 catalyst Substances 0.000 claims abstract description 54
- 239000000243 solution Substances 0.000 claims abstract description 33
- 239000011259 mixed solution Substances 0.000 claims abstract description 32
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 30
- 238000006243 chemical reaction Methods 0.000 claims abstract description 26
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 claims abstract description 23
- 239000013078 crystal Substances 0.000 claims abstract description 16
- 238000002425 crystallisation Methods 0.000 claims abstract description 16
- 239000007795 chemical reaction product Substances 0.000 claims abstract description 14
- 239000002994 raw material Substances 0.000 claims abstract description 14
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 10
- 230000001590 oxidative effect Effects 0.000 claims abstract description 10
- 239000001301 oxygen Substances 0.000 claims abstract description 10
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 10
- 238000001704 evaporation Methods 0.000 claims abstract description 8
- 238000002386 leaching Methods 0.000 claims abstract description 7
- 239000002904 solvent Substances 0.000 claims abstract description 7
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 6
- 239000012141 concentrate Substances 0.000 claims abstract description 6
- 238000001035 drying Methods 0.000 claims abstract description 6
- 230000002378 acidificating effect Effects 0.000 claims abstract description 5
- 230000003472 neutralizing effect Effects 0.000 claims abstract description 5
- 239000007800 oxidant agent Substances 0.000 claims abstract description 4
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 44
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 38
- 229910052684 Cerium Inorganic materials 0.000 claims description 33
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 23
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 claims description 20
- 229910052797 bismuth Inorganic materials 0.000 claims description 16
- 229910052751 metal Inorganic materials 0.000 claims description 16
- 239000002184 metal Substances 0.000 claims description 16
- 229910052763 palladium Inorganic materials 0.000 claims description 16
- 230000008025 crystallization Effects 0.000 claims description 11
- 229910052799 carbon Inorganic materials 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 claims description 8
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 claims description 8
- 239000011148 porous material Substances 0.000 claims description 6
- 230000035484 reaction time Effects 0.000 claims description 6
- 238000003756 stirring Methods 0.000 claims description 6
- 229910000416 bismuth oxide Inorganic materials 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 4
- 239000012297 crystallization seed Substances 0.000 claims description 4
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 claims description 3
- 229910052740 iodine Inorganic materials 0.000 claims description 3
- 239000011630 iodine Substances 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 2
- 238000003786 synthesis reaction Methods 0.000 abstract description 3
- 238000006555 catalytic reaction Methods 0.000 abstract description 2
- 230000007613 environmental effect Effects 0.000 abstract description 2
- 230000015572 biosynthetic process Effects 0.000 abstract 1
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 20
- 239000001257 hydrogen Substances 0.000 description 14
- 229910052739 hydrogen Inorganic materials 0.000 description 14
- 229910000420 cerium oxide Inorganic materials 0.000 description 12
- -1 i.e. Chemical compound 0.000 description 12
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 12
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 description 12
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 11
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 11
- 229910017604 nitric acid Inorganic materials 0.000 description 11
- 229910001451 bismuth ion Inorganic materials 0.000 description 10
- RXPAJWPEYBDXOG-UHFFFAOYSA-N hydron;methyl 4-methoxypyridine-2-carboxylate;chloride Chemical compound Cl.COC(=O)C1=CC(OC)=CC=N1 RXPAJWPEYBDXOG-UHFFFAOYSA-N 0.000 description 10
- 239000000047 product Substances 0.000 description 5
- 150000002431 hydrogen Chemical class 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000012018 catalyst precursor Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000002537 cosmetic Substances 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 239000000539 dimer Substances 0.000 description 1
- 238000004043 dyeing Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 238000004128 high performance liquid chromatography Methods 0.000 description 1
- 238000004255 ion exchange chromatography Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- UKVIEHSSVKSQBA-UHFFFAOYSA-N methane;palladium Chemical group C.[Pd] UKVIEHSSVKSQBA-UHFFFAOYSA-N 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000007639 printing Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000011550 stock solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
- C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
- C07C51/23—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of oxygen-containing groups to carboxyl groups
- C07C51/235—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of oxygen-containing groups to carboxyl groups of —CHO groups or primary alcohol groups
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/56—Platinum group metals
- B01J23/64—Platinum group metals with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
- B01J23/644—Arsenic, antimony or bismuth
- B01J23/6447—Bismuth
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Catalysts (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention provides a method for preparing high-purity glycollic acid by selective oxidation of glycol. The method comprises the following steps: (1) Taking oxygen as an oxidant, and preparing glycollic acid by selectively oxidizing raw materials of glycol and sodium hydroxide in the presence of a solvent and a catalyst; (2) Neutralizing the reaction product with phosphoric acid until the reaction product is acidic to obtain a glycolic acid mixed solution, and continuously evaporating to concentrate the content of glycollic acid to 70-80%; (3) Purifying the glycolic acid concentrated solution obtained in the step (2) by adopting a crystallization method, leaching the separated crystals, leaching, and drying in vacuum to obtain the high-purity glycolic acid. The invention realizes the synthesis of high-purity glycollic acid by high-efficiency selective catalysis of glycol reaction by a one-step method, has simple process, easily obtained raw materials, milder reaction, environmental protection and no pollution.
Description
Technical Field
The invention relates to a method for producing high-purity glycollic acid by using glycol as a raw material.
Background
Glycolic acid, i.e., glycolic acid, is an important organic synthetic raw material and chemical product, and is widely used in the fields of organic synthesis, printing and dyeing, cosmetics, electroplating, petroleum industry, etc., and its polymer can also be used as a biodegradable material in medical treatment, packaging, and other fields.
Glycolic acid was successfully produced by DuPont in 1940 using chemical synthesis, and corresponding production techniques were developed in Japan, germany, etc. Through decades of development, a series of glycollic acid synthesis methods are developed at home and abroad, wherein: the method for preparing the glycollic acid by the selective oxidation of the ethylene glycol has received wide attention in various aspects due to the single and readily available raw materials and simple process. Because of the increasing demand of the market for high-purity glycolic acid crystal products, development of a method for preparing high-purity glycolic acid by selective oxidation of ethylene glycol is of great significance.
Disclosure of Invention
The invention aims to solve the problem of providing a method for preparing high-purity glycollic acid by selective oxidation of glycol.
The method for preparing the high-purity glycollic acid by the selective oxidation of the ethylene glycol comprises the following steps:
(1) Taking oxygen as an oxidant, preparing glycolic acid by selectively oxidizing raw materials of glycol and sodium hydroxide in the presence of a solvent and Pd-Bi-CeO 2/C catalyst, wherein the molar ratio of the raw materials is that the glycol: sodium hydroxide 1.0: (0.25-1.5), wherein the solvent is water; the dosage of the catalyst is 0.5 to 2 weight per mill of ethylene glycol based on the ethylene glycol; the catalyst consists of metal palladium serving as an active component, active carbon serving as a carrier, and metal bismuth and cerium dioxide serving as auxiliary catalysts, wherein the content of the metal palladium is 0.1-1.5% of the weight of the carrier, and the total content of the metal bismuth and the cerium dioxide is 0.25-1.5% of the weight of the carrier;
(2) Neutralizing the reaction product with phosphoric acid until the reaction product is acidic to obtain a glycolic acid mixed solution; continuing evaporating to concentrate the content of the glycollic acid to 70-80%;
(3) Purifying the glycolic acid concentrated solution obtained in the step (2) by adopting a crystallization method, leaching the separated crystals, leaching, and drying in vacuum to obtain the high-purity glycolic acid.
According to the scheme, the reaction pressure for preparing the glycollic acid by selectively oxidizing the glycol in the step (1) is 0.1-0.3 MPa, the reaction temperature is 70-90 ℃, the oxygen airspeed is 1500-2500 h -1, and the reaction time is 4-8 h.
According to the scheme, the raw material molar ratio in the step (1) is ethylene glycol: sodium hydroxide is between 1: (1.0-1.5).
According to the scheme, the dosage of the catalyst in the step (1) is 0.5-1.5 wt%of ethylene glycol.
According to the scheme, the reaction pressure in the step (1) is 0.2-0.3 MPa, the reaction temperature is 70-80 ℃ and the reaction time is 4-6 h.
According to the above scheme, it is preferable to ensure that the conversion of glycolic acid produced by selective oxidation in step (1) is higher than 80%, more preferably higher than 90%, and the selectivity is higher than 80%, and still more preferably higher than 90%.
According to the scheme, the content of the glycollic acid is concentrated to 70-78% by evaporation in the step (2).
According to the scheme, the evaporating and concentrating pressure in the step (2) is minus 0.05-0.1 MPa, and the temperature is 30-40 ℃.
According to the scheme, the crystallization temperature in the step (3) is minus 16 ℃ to minus 5 ℃, and stirring is carried out while cooling.
According to the scheme, the cooling rate in the step (3) is 1-2 ℃/min.
According to the scheme, in the step (3), the glycolic acid crystallization seed crystal is added at the temperature close to the crystallization temperature, the adding amount of the crystallization seed crystal is 1-2.5 wt%, and the seed crystal is added and maintained for 6-12 h in the stirring process.
According to the scheme, the vacuum drying temperature of the glycolic acid crystal in the step (3) is 60-70 ℃.
According to the scheme, in the Pd-Bi-CeO 2/catalyst, the total content of the metal bismuth and the cerium oxide is preferably 0.3-1.2% of the weight of the carrier, wherein the content of the metal bismuth is 0.2-0.9%, and the content of the cerium oxide is 0.1-0.6%.
According to the scheme, in the Pd-Bi-CeO 2/catalyst, the carrier is activated carbon, preferably flaky activated carbon or granular activated carbon.
According to the scheme, in the Pd-Bi-CeO 2/catalyst, the specific surface area of the active carbon carrier is 800-1500 m 2/g, preferably 1000-1200 m 2/g.
According to the scheme, in the Pd-Bi-CeO 2/catalyst, the pore volume of the active carbon carrier is 0.6-0.7 ml/g, the pore diameter is 8-20 nm, the iodine value is 600-1100, the preferred pore volume is 0.5-0.8 ml/g, the pore diameter is 2-30 nm, and the iodine value is 400-1300.
The preparation method of the Pd-Bi-CeO 2/catalyst comprises the following steps:
Dissolving nitrate of metal bismuth and cerium in dilute nitric acid or water to prepare corresponding solution, adding palladium chloride acid solution into the solution to form mixed solution, and then immersing the weighed corresponding carrier in the mixed solution for 3-18 h to obtain the catalyst precursor.
Drying the catalyst precursor at 100-120 deg.c for 2-5 hr, roasting at 200-500 deg.c for 2-5 hr, and reducing with hydrogen at 230-280 deg.c for 2-4 hr to obtain the catalyst.
According to the scheme, the process of impregnating the carrier with the metal mixed solution adopts water bath heating, and the temperature is 40-60 ℃.
According to the scheme, the hydrogen content in the hydrogen reducing atmosphere used for reduction is 1-10%, and the balance is high-purity nitrogen.
The Pd-Bi-CeO 2/C catalyst provided by the invention takes active carbon as a carrier, takes metal palladium as a main catalytic component, takes bismuth and cerium dioxide as a cocatalyst, can achieve the purpose of synthesizing glycollic acid by efficiently and selectively catalyzing glycol reaction under the condition of low metal Pd loading capacity, and therefore, on the basis of ensuring low impurity content of reaction products obtained with high conversion rate and high selectivity, the invention further comprises the following steps of: 1. neutralizing the reaction product with phosphoric acid until the reaction product is acidic to obtain a glycolic acid mixed solution; 2. the concentration of the glycolic acid crystallization stock solution is regulated, and further the concentration temperature is regulated, so that the polymerization of the glycolic acid at high temperature is avoided, and the intermolecular dehydration polymerization of the glycolic acid in water is reduced to form a dimer or a multimer; 3. meanwhile, the high-purity glycolic acid crystal is obtained by further matching with the proper selection of the crystallization temperature range. The glycol is reacted to synthesize the reaction product with high conversion rate and high selectivity and low impurity content, which provides a precondition for obtaining the final high-purity glycolic acid target product and provides a guarantee for the yield of the target product.
The invention has the beneficial effects that:
The method for preparing high-purity glycollic acid by selective oxidation of glycol provided by the invention realizes high-efficiency selective catalysis of glycol reaction to synthesize high-purity glycollic acid by a one-step method, has the advantages of simple process, easily obtained raw materials, milder reaction, environmental protection and no pollution; and the device can realize poly-generation with the existing coal-to-glycol industrial device, so that the surplus production of glycol is solved, and the device is also an effective supplement of a glycol industrial chain.
Detailed Description
The present invention is described in further detail below with reference to examples.
Preparation of Pd-Bi-CeO 2/C catalyst:
Example 1
Bismuth nitrate was dissolved in dilute nitric acid, followed by addition of a palladium chloride solution to form a mixed solution, the concentration of bismuth ions in the mixed solution was 0.022g/mL, and the concentration of Pd was 0.015g/mL. Activated carbon with a specific surface area of 1000m 2/g was immersed in this solution at 60℃for 6 hours, dried at 120℃for 2 hours, calcined at 350℃for 3 hours, reduced at 260℃with 3% hydrogen for 3 hours and then taken out to give catalyst 1. In the obtained catalyst 1, the palladium content was 1.0% by mass of the carrier, and the bismuth content was 1.5% by mass of the carrier.
Example 2
Cerium nitrate and deionized water are prepared into an aqueous solution, then palladium chloride solution is added to form a mixed solution, the concentration of cerium ions in the mixed solution is 0.022g/mL, and the concentration of Pd is 0.015g/mL. Activated carbon with a specific surface area of 1000m 2/g was immersed in this solution at 60℃for 6 hours, dried at 120℃for 2 hours, calcined at 400℃for 3 hours, reduced at 260℃with 3% hydrogen for 3 hours and then taken out to give catalyst 2. Catalyst 2 was obtained. In the obtained catalyst 2, the palladium content was 1.0% by mass of the support, and the cerium content (cerium oxide was calculated as cerium content) was 1.5% by mass of the support.
Example 3
Bismuth nitrate and cerium nitrate were dissolved in dilute nitric acid, followed by addition of a palladium chloride solution to form a mixed solution, the concentration of bismuth ions in the mixed solution being 0.0135g/mL, the concentration of cerium ions being 0.0135g/mL, and the concentration of Pd being 0.015g/mL. Activated carbon with a specific surface area of 1000m 2/g was immersed in this solution at 60℃for 6 hours, dried at 120℃for 2 hours, calcined at 400℃for 3 hours, reduced at 260℃with 3% hydrogen for 3 hours and then taken out to give catalyst 3. In the obtained catalyst 3, the palladium content was 1.0% by mass of the support, the bismuth content was 0.9% by mass of the support, and the cerium content (cerium oxide was calculated as cerium content) was 0.9% by mass of the support.
Example 4
Bismuth nitrate and cerium nitrate were dissolved in dilute nitric acid, followed by addition of a palladium chloride solution to form a mixed solution, the concentration of bismuth ions in the mixed solution was 0.009g/mL, the concentration of cerium ions was 0.009g/mL, and the concentration of Pd was 0.015g/mL. Activated carbon with a specific surface area of 1000m 2/g was immersed in this solution at 60℃for 6 hours, dried at 120℃for 2 hours, calcined at 400℃for 3 hours, reduced at 260℃with 3% hydrogen for 3 hours and then taken out to give catalyst 4. In the obtained catalyst 4, the palladium content was 1.0% by mass of the support, the bismuth content was 0.6% by mass of the support, and the cerium content (cerium oxide was calculated as cerium content) was 0.6% by mass of the support.
Example 5
Bismuth nitrate and cerium nitrate were dissolved in dilute nitric acid, followed by addition of a palladium chloride solution to form a mixed solution, the concentration of bismuth ions in the mixed solution was 0.0135g/mL, the concentration of cerium ions was 0.009g/mL, and the concentration of Pd was 0.015g/mL. Activated carbon with a specific surface area of 1000m 2/g was immersed in this solution at 60℃for 6 hours, dried at 120℃for 2 hours, calcined at 400℃for 3 hours, reduced at 260℃for 3 hours with 3% hydrogen, and taken out to give catalyst 5. In the obtained catalyst 5, the palladium content was 1.0% by mass of the support, the bismuth content was 0.9% by mass of the support, and the cerium content (cerium oxide was calculated as cerium content) was 0.6% by mass of the support.
Example 6
Bismuth nitrate and cerium nitrate were dissolved in dilute nitric acid, followed by addition of a palladium chloride solution to form a mixed solution, the concentration of bismuth ions in the mixed solution was 0.009g/mL, the concentration of cerium ions was 0.0135g/mL, and the concentration of Pd was 0.015g/mL. Activated carbon with a specific surface area of 1000m 2/g was immersed in this solution at 60℃for 6 hours, dried at 120℃for 2 hours, calcined at 400℃for 3 hours, reduced at 260℃with 3% hydrogen for 3 hours and then taken out to give catalyst 6. In the obtained catalyst 6, the palladium content was 1.0% by mass of the support, the bismuth content was 0.6% by mass of the support, and the cerium content (cerium oxide was calculated as cerium content) was 0.9% by mass of the support.
Example 7
Bismuth nitrate and cerium nitrate were dissolved in dilute nitric acid, followed by addition of a palladium chloride solution to form a mixed solution, the concentration of bismuth ions in the mixed solution was 0.003g/mL, the concentration of cerium ions was 0.009g/mL, and the concentration of Pd was 0.015g/mL. Activated carbon with a specific surface area of 1000m 2/g was immersed in this solution at 60℃for 6 hours, dried at 120℃for 2 hours, calcined at 400℃for 3 hours, reduced at 260℃with 3% hydrogen for 3 hours and then taken out to give catalyst 7. In the obtained catalyst 7, the palladium content was 1.0% by mass of the support, the bismuth content was 0.2% by mass of the support, and the cerium content (cerium oxide was calculated as cerium content) was 0.6% by mass of the support.
Example 8
Bismuth nitrate and cerium nitrate were dissolved in dilute nitric acid, followed by addition of a palladium chloride solution to form a mixed solution, the concentration of bismuth ions in the mixed solution was 0.0135g/mL, the concentration of cerium ions was 0.0015g/mL, and the concentration of Pd was 0.015g/mL. Activated carbon with a specific surface area of 1000m 2/g was immersed in this solution at 60℃for 6 hours, dried at 120℃for 2 hours, calcined at 400℃for 3 hours, reduced at 260℃with 3% hydrogen for 3 hours and then taken out to give catalyst 8. In the obtained catalyst 8, the palladium content was 1.0% by mass of the support, the bismuth content was 0.9% by mass of the support, and the cerium content (cerium oxide was calculated as cerium content) was 0.1% by mass of the support.
Example 9
Bismuth nitrate and cerium nitrate were dissolved in dilute nitric acid, followed by addition of a palladium chloride solution to form a mixed solution, the concentration of bismuth ions in the mixed solution was 0.003g/mL, the concentration of cerium ions was 0.0015g/mL, and the concentration of Pd was 0.015g/mL. Activated carbon with a specific surface area of 1000m 2/g was immersed in this solution at 60℃for 6 hours, dried at 120℃for 2 hours, calcined at 400℃for 3 hours, reduced at 260℃with 3% hydrogen for 3 hours and then taken out to give catalyst 9. In the obtained catalyst 9, the palladium content was 1.0% by mass of the support, the bismuth content was 0.2% by mass of the support, and the cerium content (cerium oxide was calculated as cerium content) was 0.1% by mass of the support.
Example 10
Bismuth nitrate and cerium nitrate were dissolved in dilute nitric acid, followed by addition of a palladium chloride solution to form a mixed solution, the concentration of bismuth ions in the mixed solution was 0.003g/mL, the concentration of cerium ions was 0.00075g/mL, and the concentration of Pd was 0.015g/mL. Activated carbon with a specific surface area of 1000m 2/g was immersed in this solution at 60℃for 6 hours, dried at 120℃for 2 hours, calcined at 400℃for 3 hours, reduced at 260℃for 3 hours with 3% hydrogen, and taken out to give catalyst 10. In the obtained catalyst 10, the palladium content was 1.0% by mass of the support, the bismuth content was 0.2% by mass of the support, and the cerium content (cerium oxide was calculated as cerium content) was 0.05% by mass of the support.
Example 11
Bismuth nitrate and cerium nitrate were dissolved in dilute nitric acid, followed by addition of a palladium chloride solution to form a mixed solution, the concentration of bismuth ions in the mixed solution was 0.0015g/mL, the concentration of cerium ions was 0.0015g/mL, and the concentration of Pd was 0.015g/mL. Activated carbon having a specific surface area of 1000m 2/g was immersed in this solution at 60℃for 6 hours, dried at 120℃for 2 hours, calcined at 400℃for 3 hours, reduced at 260℃for 3 hours with 3% hydrogen, and taken out to give catalyst 11. In the obtained catalyst 11, the palladium content was 1.0% by mass of the support, the bismuth content was 0.1% by mass of the support, and the cerium content (cerium oxide was calculated as cerium content) was 0.1% by mass of the support.
The method for preparing the high-purity glycollic acid by selectively oxidizing the ethylene glycol based on the catalyst Pd-Bi-CeO 2/C comprises the following steps of:
(1) Taking oxygen as an oxidant, and preparing glycolic acid by selectively oxidizing raw materials of glycol and sodium hydroxide in the presence of a solvent and a catalyst, wherein the molar ratio of the raw materials is that the glycol is as follows: sodium hydroxide 1.0: (0.25-1.5), wherein the solvent is water, and the catalyst is palladium-carbon catalyst; the dosage of the catalyst is 0.5 to 2 weight per mill based on ethylene glycol, the reaction pressure is 0.1 to 0.3MPa, the reaction temperature is 70 to 90 ℃, the oxygen airspeed is 1500 to 2500h -1, and the reaction time is 4 to 8h;
(2) Neutralizing the reaction product with phosphoric acid until the reaction product is acidic to obtain a glycolic acid mixed solution; continuing evaporating to concentrate the content of the glycollic acid to 70-80%;
(3) Purifying the glycolic acid concentrated solution obtained in the step (2) by adopting a crystallization method, leaching the separated crystals, leaching, and drying in vacuum to obtain the high-purity glycolic acid.
Further description is made of the process for producing glycolic acid, and the catalysts of example 4, example 7, example 8 and example 9 are specifically used in the following processes.
Examples 1 to 10 used the catalyst of example 7, and examples 11 to 13 used the catalysts of example 4, example 8 and example 9, respectively
250G of water is added into a 500mL autoclave with stirring function, and the mol ratio of glycol to sodium hydroxide is 1: (0.75-1.5), the dosage of the Pd-Bi-CeO 2/C catalyst is based on the mass of glycol. Setting a reaction kettle heating program to gradually heat reactants, introducing oxygen into the reaction kettle in the heating process (the oxygen airspeed is 2000h -1) and maintaining the set reaction pressure, stopping introducing oxygen after the reactants reach the preset temperature, and finishing the required reaction time at the set temperature. After the reaction is finished and cooled, decompression is carried out to obtain light yellow liquid, and specific reaction conditions of each example are shown in table 1.
The reaction product composition was analyzed by gas chromatography and ion chromatography, and the ethylene glycol conversion, glycolic acid selectivity and yield were calculated, and the results are shown in table 2.
TABLE 1
TABLE 2
| Examples | Glycol conversion% | Glycolic acid selectivity,% | Glycolic acid yield% |
| 1 | 78 | 65 | 50.7 |
| 2 | 81 | 68 | 55.1 |
| 3 | 89 | 80 | 71.2 |
| 4 | 86 | 86 | 74.0 |
| 5 | 90 | 94 | 84.6 |
| 6 | 93 | 96 | 89.3 |
| 7 | 93 | 90 | 83.7 |
| 8 | 95 | 96 | 91.2 |
| 9 | 97 | 98 | 95.1 |
| 10 | 99 | 89 | 88.1 |
| 11 | 91 | 93 | 84.6 |
| 12 | 98 | 91 | 89.2 |
| 13 | 94 | 90 | 84.6 |
Glycolic acid crystallization and purification process
Examples 14 to 26
The oxidation reaction product was neutralized with phosphoric acid to obtain a glycolic acid mixed solution, the glycolic acid solutions obtained in examples 5 to 10 were mixed (glycolic acid content: about 23 wt%) and 700g of the mixed solution was put into a 1000mL three-necked flask, and distilled under reduced pressure at 30 to 40℃and-0.05 MPa to remove water and concentrate the glycolic acid to a concentration of 70 to 80%.
400G of concentrated ethanol acid solution was added to a 500mL flask equipped with a stirrer and a cooling device, and the flask was cooled to a predetermined crystallization temperature. And (3) when the temperature is reduced to be close to the crystallization temperature of 0.5 ℃, adding glycolic acid seed crystals, wherein the adding amount is 1-2.5 percent, specifically 1 percent, of the content of the glycolic acid in the concentrated solution, and maintaining the temperature and stirring for 6-12 hours to completely separate out the glycolic acid crystals.
And transferring the materials in the flask, filtering, washing and drying in vacuum to obtain high-purity glycolic acid crystals, and measuring the purity of the product by using high performance liquid chromatography.
The glycolic acid content of the concentrated solutions in examples 14 to 26, the crystallization temperature range, the time taken for the crystallization process, and the specific purity of glycolic acid are shown in Table 3.
TABLE 3 Table 3
Claims (10)
1. The method for preparing the high-purity glycollic acid by the selective oxidation of the ethylene glycol is characterized by comprising the following steps of: the method comprises the following steps:
(1) Taking oxygen as an oxidant, preparing glycolic acid by selectively oxidizing raw materials of glycol and sodium hydroxide in the presence of a solvent and Pd-Bi-CeO 2/C catalyst, wherein the molar ratio of the raw materials is that the glycol: sodium hydroxide is 1: (1.0-1.5), wherein the solvent is water; the dosage of the catalyst is 0.5 to 2 weight per mill of ethylene glycol based on the ethylene glycol; the catalyst consists of metal palladium serving as an active component, active carbon serving as a carrier, and metal bismuth and cerium dioxide serving as auxiliary catalysts, wherein the content of the metal palladium is 0.1% -1.5% of the weight of the carrier, and the total content of the metal bismuth and the cerium dioxide is 0.25% -1.5% of the weight of the carrier;
(2) Neutralizing the reaction product with phosphoric acid until the reaction product is acidic to obtain a glycolic acid mixed solution; continuing evaporating to concentrate the content of the glycollic acid to 70-80%;
(3) Purifying the glycolic acid concentrated solution obtained in the step (2) by adopting a crystallization method, adding glycolic acid crystallization seed crystals at the temperature close to the crystallization temperature in the crystallization method, wherein the adding amount of the crystallization seed crystals is 1-2.5wt%, filtering the separated crystals, leaching, and drying in vacuum to obtain the high-purity glycolic acid.
2. The method according to claim 1, characterized in that: the reaction pressure for preparing glycollic acid by the selective oxidation of glycol in the step (1) is 0.1-0.3 MPa, the reaction temperature is 70-90 ℃, the oxygen airspeed is 1500-2500 h -1, and the reaction time is 4-8 h.
3. The method according to claim 1, characterized in that: the conversion rate of glycolic acid prepared by selective oxidation in the step (1) is higher than 80%, and the selectivity is higher than 80%.
4. The method according to claim 1, characterized in that: the molar ratio of the raw materials in the step (1) is glycol: sodium hydroxide is between 1: (1.0 to 1.5).
5. The method according to claim 1, characterized in that: the reaction pressure of the step (1) is 0.2-0.3 MPa, the reaction temperature is 70-80 ℃ and the reaction time is 4-6 h; evaporating in the step (2) to concentrate the content of the glycollic acid to 70-78%.
6. The method according to claim 1, characterized in that: the catalyst dosage in the step (1) is 0.5 to 1.5 weight per mill of the ethylene glycol; the evaporating and concentrating pressure in the step (2) is minus 0.05-0.1 MPa, and the temperature is 30-40 ℃; the crystallization temperature in the step (3) is-16 ℃ to-5 ℃, and stirring is carried out while cooling.
7. The method according to claim 1, characterized in that: and (3) adding seed crystals in the stirring process and maintaining the temperature for 6-12 h.
8. The method according to claim 1, characterized in that: in the Pd-Bi-CeO 2/catalyst, the content of cerium dioxide is calculated by the content of cerium, the total content of metal bismuth and cerium dioxide is 0.3% -1.2% of the weight of the carrier, wherein the content of metal bismuth is 0.2% -0.9%, and the content of cerium dioxide is calculated by the content of cerium is 0.1% -0.6%.
9. The method according to claim 1, characterized in that: in the Pd-Bi-CeO 2/catalyst, the active carbon carrier is flaky active carbon or granular active carbon; the specific surface area of the used active carbon carrier is 800-1500 m 2/g.
10. The method according to claim 1, characterized in that: in the Pd-Bi-CeO 2/catalyst, the pore volume of the active carbon carrier used is 0.6-0.7 mL/g, the pore diameter is 8-20 nm, and the iodine value is 600-1100.
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