A method for preparing dimethyl 2,5-furandicarboxylate by oxidizing esterification of 2,5-furandimethanol with a cobalt-zinc carbon-based material

Abstract

This invention provides a method for synthesizing dimethyl 2,5-furandicarboxylate by oxidative esterification of 2,5-furandiethanol using a cobalt-zinc-based carbon material, belonging to the field of catalytic synthesis technology. This method uses 2,5-furandiethanol as a raw material, molecular oxygen as an oxidant, and a cobalt-zinc-based carbon material as a heterogeneous catalyst to prepare dimethyl 2,5-furandicarboxylate via a one-step oxidative esterification reaction in methanol solvent using high-performance liquid phase. The cobalt-zinc-based material is prepared by mixing a certain amount of cobalt salt, zinc salt, and organic nitrogen-containing compound ligand to obtain a precursor, which is then calcined at 500-1100℃ under an inert atmosphere for 0.5-24 h. The oxidative esterification method provided by this invention is mild and efficient, and the catalyst is inexpensive and readily available, making this method highly practical and applicable.

Description

Technical Field

[0001] This application relates to the field of catalytic synthesis technology, and to a method for preparing dimethyl 2,5-furandicarboxylate by oxidative esterification of 2,5-furandiethanol with cobalt zinc carbon-based materials. Background Technology

[0002] The use of green and renewable bio-based raw materials to replace traditional fossil-based resources has attracted widespread attention. 2,5-Furandicarboxylic acid, as one of 12 high-value-added bio-based chemical substances, can be used to synthesize a variety of fine chemical products, and as an important monomer for corrosion-resistant plastics, it has enormous market potential.

[0003] Dimethyl 2,5-furandicarboxylate, an important derivative compound of 2,5-furandicarboxylic acid, can be used in the production of bio-based polyester polyethylene furandicarboxylate (PEF). PEF is a novel recyclable engineering plastic whose melting temperature, Young's modulus, glass transition temperature, and tensile strength are highly similar to those of the commonly used plastic polyethylene terephthalate (PET). It is also biodegradable, meeting the requirements of green chemistry and green industry development, and possesses enormous application potential. Compared to 2,5-furandicarboxylic acid, dimethyl 2,5-furandicarboxylate is easier to produce due to its good solubility and stability, and it effectively avoids decarboxylation reactions at high temperatures, thereby improving product yield. Therefore, dimethyl 2,5-furandicarboxylate has extremely high application value.

[0004] Currently, dimethyl 2,5-furandicarboxylate is mainly produced using 5-hydroxymethylfurfural (HMF) as a raw material. However, HMF is highly hygroscopic and extremely unstable under alkaline conditions, limiting the industrial production of dimethyl 2,5-furandicarboxylate. 2,5-furandiethanol has a similar structure to HMF, and compared to HMF, 2,5-furandiethanol is more stable under alkaline conditions. Therefore, developing a new, environmentally friendly, inexpensive, and efficient method for preparing dimethyl 2,5-furandicarboxylate via oxidative esterification using 2,5-furandiethanol as a raw material is of great significance.

[0005] This invention uses molecular oxygen as the oxygen source and cobalt-zinc carbon-based materials as catalysts to efficiently oxidize 2,5-furandiethanol to dimethyl 2,5-furandicarboxylate in one step. The reaction conditions are mild, safe and environmentally friendly, and the separation of the heterogeneous catalyst and the product is simple. Summary of the Invention

[0006] The purpose of this invention is to provide a novel method for preparing dimethyl 2,5-furandimethyl acid by oxidative esterification of 2,5-furandimethyl alcohol. This method uses a cobalt-zinc carbon-based material as a catalyst and molecular oxygen as the oxygen source to oxidatively esterify 2,5-furandimethyl alcohol to dimethyl 2,5-furandimethyl acid in a methanol solution.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for synthesizing dimethyl 2,5-furandimethyl ester from 2,5-furandimethyl alcohol using a cobalt-zinc carbon-based material as a catalyst. This method utilizes a cobalt-zinc-based material as a catalyst to oxidize 2,5-furandimethyl alcohol to dimethyl 2,5-furandimethyl ester. Specifically, it includes the following steps:

[0009] (1) Preparation of cobalt-zinc carbon-based catalysts

[0010] Cobalt nitrate, zinc nitrate, and nitrogen-containing organic ligands are mixed and added to a solvent. The mixture is stirred at 25-150℃ for 0.5-8 hours, cooled to room temperature, and the solvent is removed by rotary evaporation. After drying, the mixture is heat-treated in an inert atmosphere at 500-1100℃ for 0.5-24 hours and then cooled to obtain a cobalt-zinc carbon-based catalyst.

[0011] (2) Preparation of dimethyl 2,5-furandicarboxylate

[0012] 2,5-furandiethanol, cobalt-zinc carbon-based catalyst, and methanol are added to a reactor. The amount of methanol is 2-200 times the mass of 2,5-furandiethanol, and the amount of cobalt-zinc-based catalyst is 0.01-2 times the mass of the raw material 2,5-furandiethanol. Molecular oxygen is introduced as an oxygen source, the reactor is sealed, and the reaction temperature is set before stirring.

[0013] The molar ratio of cobalt nitrate to zinc nitrate in step (1) is 1:0.5-1:10; the molar ratio of cobalt nitrate to the total nitrogen-containing organic ligand is 1:1-1:40; and the amount of solvent used is 10-120 times the total mass of the nitrogen-containing organic ligand.

[0014] The nitrogen-containing organic ligand mentioned in step (1) is one or more of polyaniline, dicyandiamide, melamine, aniline, benzylamine, o-phenylenediamine, triazole, pyrrole, pyridine, quinoline, purine, 1,10-phenanthroline, and 2-methylimidazole.

[0015] The inert atmosphere mentioned in step (1) is one or more of nitrogen, argon, and helium.

[0016] The molecular oxygen in the reaction described in step (2) comes from air, oxygen, or a gas containing oxygen, with a partial pressure of 0.02-2 MPa.

[0017] The reaction temperature in step (2) is 25-120℃, and the stirring reaction time is 0.5-72h.

[0018] The beneficial effects of this invention are as follows:

[0019] (1) The present invention uses cobalt zinc carbon-based material as catalyst to efficiently oxidize 2,5-furandiethanol to dimethyl 2,5-furandicarboxylate in one pot.

[0020] (2) Unlike the high-temperature gas phase oxidation reaction process, the present invention adopts a mild oxygen molecule oxidation reaction system coupled under mild conditions.

[0021] (3) Unlike homogeneous catalytic oxidation systems, this invention uses a multiphase cobalt-zinc-carbon-based composite material as a catalyst, which is a composite material composed of four elements: cobalt, zinc, nitrogen, carbon and oxygen. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] Example 1

[0024] 2 mmol cobalt nitrate hexahydrate, 8 mmol zinc nitrate hexahydrate, 32 mmol 2-methylimidazole, and 32 mmol aniline were added to 160 g of water and stirred at 30 °C for 4 h. After drying, the mixture was heat-treated in a tube furnace at 900 °C for 2 h under a nitrogen atmosphere to obtain a cobalt-zinc carbon-based material solid powder, denoted as catalyst A.

[0025] 0.128 g of 2,5-furandiethanol, 0.06 g of catalyst A, and 7.1 g of methanol were added to a reactor, and oxygen was introduced at 0.8 MPa. The mixture was heated to 80 °C with stirring and run for 4 hours. Then, it was cooled to room temperature and carefully reduced to atmospheric pressure. Samples were taken for quantitative analysis of the product by liquid chromatography. The conversion rate of 2,5-furandiethanol was 99%, and the selectivity for dimethyl 2,5-furandicarboxylate was 95%.

[0026] Example 2

[0027] 6 mmol of cobalt nitrate hexahydrate, 3 mmol of zinc nitrate hexahydrate, 3 mmol of 2-methylimidazole, and 3 mmol of benzylamine were added to 5.67 g of methanol and stirred at 25 °C for 6 h. After drying, the mixture was heat-treated in a tube furnace at 500 °C for 24 h under an argon atmosphere to obtain a cobalt-zinc carbon-based material solid powder, denoted as catalyst B.

[0028] 1.28 g of 2,5-furandiethanol, 0.67 g of catalyst B, and 2.56 g of methanol were added to a reactor, and oxygen was introduced at 1.0 MPa. The mixture was heated to 120 °C with stirring and run for 8 hours. Then, it was cooled to room temperature and carefully reduced to atmospheric pressure. Samples were taken for quantitative analysis of the product by liquid chromatography. The conversion rate of 2,5-furandiethanol was 99%, and the selectivity for dimethyl 2,5-furandicarboxylate was 89%.

[0029] Example 3

[0030] 0.5 mmol cobalt nitrate hexahydrate, 5 mmol zinc nitrate hexahydrate, 10 mmol 2-methylimidazole, and 10 mmol quinoline were added to 253.5 g of water and stirred at 40 °C for 8 h. After drying, the mixture was heat-treated in a tube furnace at 900 °C for 2 h under a nitrogen atmosphere to obtain a cobalt-zinc carbon-based material solid powder, denoted as catalyst C.

[0031] 1.28 g of 2,5-furandiethanol, 0.0128 g of catalyst C, and 100 g of methanol were added to a reactor, and oxygen was introduced at 2.0 MPa. The mixture was heated to 120 °C with stirring and run for 0.5 h. Then, it was cooled to room temperature and carefully reduced to atmospheric pressure. Samples were taken for quantitative analysis of the product by liquid chromatography. The conversion rate of 2,5-furandiethanol was 99%, and the selectivity for dimethyl 2,5-furandicarboxylate was 91%.

[0032] Example 4

[0033] 8 mmol of cobalt nitrate hexahydrate, 8 mmol of zinc nitrate hexahydrate, 32 mmol of 2-methylimidazole, and 32 mmol of purine were added to 160 g of water and stirred at 150 °C for 0.5 h. After drying, the mixture was heat-treated in a tube furnace at 1100 °C for 0.5 h under a nitrogen atmosphere to obtain a cobalt-zinc carbon-based material solid powder, denoted as catalyst D.

[0034] 0.128 g of 2,5-furandiethanol, 0.256 g of catalyst D, and 25.6 g of methanol were added to a reactor, and the mixture was stirred at 25 °C in air for 72 h. Samples were taken for quantitative analysis of the product by liquid chromatography. The conversion rate of 2,5-furandiethanol was 99%, and the selectivity for dimethyl 2,5-furandicarboxylate was 94%.

[0035] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for preparing dimethyl 2,5-furandicarboxylate by oxidative esterification of 2,5-furandimethyl alcohol with cobalt-zinc carbon-based materials, specifically comprising the following steps: Step 1: Preparation of cobalt-zinc based catalysts: Cobalt nitrate, zinc nitrate, and nitrogen-containing organic ligands are mixed and added to a solvent. The mixture is stirred at 25-150℃ for 0.5-8h, cooled to room temperature, and the solvent is removed by rotary evaporation. After drying, the mixture is heat-treated in an inert atmosphere at 500-1100℃ for 0.5-24h and then cooled to obtain a cobalt-zinc carbon-based catalyst. Step 2: Preparation of dimethyl 2,5-furandicarboxylate: 2,5-furandiethanol, cobalt-zinc carbon-based catalyst, and methanol were added to the reactor; molecular oxygen was introduced as an oxygen source, the reactor was sealed, and the reaction temperature was set before stirring. The nitrogen-containing organic ligand in the catalyst preparation step is one or more of the following: polyaniline, dicyandiamide, melamine, aniline, benzylamine, o-phenylenediamine, triazole, pyrrole, pyridine, quinoline, purine, 1,10-phenanthroline, and 2-methylimidazole. In the catalyst preparation step, the inert atmosphere is one or a mixture of nitrogen, argon, and helium.

2. The method according to claim 1, characterized in that, In the catalyst preparation step, the molar ratio of cobalt nitrate to zinc nitrate is 1:0.5-1:10; the molar ratio of cobalt nitrate to the total nitrogen-containing organic ligand is 1:1-1:40; and the amount of solvent used is 10-120 times the total mass of the nitrogen-containing organic ligand.

3. The method according to claim 1, characterized in that, In the preparation steps of dimethyl 2,5-furandicarboxylate, the molecular oxygen comes from air, oxygen, or a gas containing oxygen, and the partial pressure of oxygen is 0.02-2 MPa.

4. The method according to claim 1, characterized in that, In the preparation steps of the 2,5-furandicarboxylic acid dimethyl ester, the reaction temperature is 25-120℃ and the stirring reaction time is 0.5-72h.

5. According to the method of claim 1, the amount of methanol used is 2-200 times the mass of 2,5-furandiethanol, and the amount of cobalt-zinc based catalyst used is 0.01-1 times the mass of the raw material 2,5-furandiethanol.