Method for preparing methylation reaction catalyst and tetramethylammonium methyl carbonate

Abstract

The present invention discloses a method for preparing a methylation reaction catalyst and tetramethylammonium methyl carbonate. The present invention uses boron nitride ceramic as a carrier, and under the action of polyether, anchors metal sites, and realizes functionalization reaction of C-H bonds by adjusting the steric hindrance of transition metals and long-chain hydrocarbons; surface grafting is performed with organic amines, so that the surface of the boron nitride ceramic is grafted to form a catalytic surface of -N-Fe- functional groups, and the orbital hybridization between Fe-N-C provides a unique catalytic effect, and anchoring Fe by N is conducive to improving the single-atom dispersibility of Fe, further improving the catalytic effect. The addition of co-catalyst Al, as a Lewis acid, can adjust the selectivity and reaction rate of the reaction. The present catalytic system has high selectivity, greatly improving the spatiotemporal benefit of TMAC, and the catalyst structure is stable, acid and alkali resistant, and as a heterogeneous catalyst, it is easy to separate, does not introduce impurities into the system, and can maintain the stability of catalytic performance for a long time.

Description

Technical Field

[0001] The invention relates to the fields of catalysts and organic synthesis, and in particular to a catalyst for methylation reaction and a method for preparing tetramethylammonium methyl carbonate. Background Art

[0002] Tetramethylammonium bicarbonate (TMAC) is a raw material for the electrolytic production of tetramethylammonium hydroxide (TMAH). TMAH is used as a catalyst and surfactant, particularly as a cleaning agent for circuit boards and electronic chips. The current mainstream process for producing TMAH involves preparing TMAC from trimethylamine (TMA) and dimethyl carbonate (DMC), followed by electrolysis to produce TMAH.

[0003] The production of TMAC adopts the method of methylating TMA and DMC in methanol solvent. The reaction is a first-order reaction of TMA and DMC, which has severe reaction tailing, takes a long time to reach the end point, and requires a large reactor design size.

[0004] For example, CN107417539A discloses a method for synthesizing tetramethylammonium bicarbonate by connecting a kettle reactor in series with a tubular reactor. This invention features low operating pressure, simple synthesis methods and equipment, and a small footprint. Current optimization efforts for the preparation of tetramethylammonium bicarbonate have primarily focused on reactor selection and process optimization, but the time and space efficiency remains low.

[0005] TMCA products on the market are generally required to be electronic grade, thus avoiding the addition of foreign substances, such as catalysts, during the synthesis process. However, only CN113735713A discloses a one-step synthesis of TMAC using an organic amine-modified molecular sieve as a catalyst, providing a solution for improving space-time yield. This invention conducts the reaction in aqueous solution, where DMC undergoes hydrolysis, achieving a maximum yield of 96%. Summary of the Invention

[0006] The present invention aims to overcome the above technical problems and provides a method for preparing a methylation reaction catalyst and tetramethylammonium methylcarbonate. The boron nitride ceramic of the present invention has excellent catalytic performance, high selectivity, and low side reaction selectivity, greatly improving the time and space benefits of TMAC. In addition, the catalyst has a stable structure and is acid and alkali resistant. As a heterogeneous catalyst, it is easy to separate and does not introduce impurities (especially metal impurities) into the system, thereby maintaining the stability of the catalytic performance for a long time.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing a methylation reaction catalyst comprises the following steps:

[0009] (1) pickling the boron nitride ceramic, washing with water until neutral, and drying;

[0010] (2) Under nitrogen protection, soaking the product of step (1) in a solvent, adding a surfactant and a pore-forming agent, and then adding organic iron and organic aluminum, reacting for 2 to 8 hours, and drying to obtain a metal-loaded catalyst;

[0011] (3) heating the product of step (2) to 120-240° C. for 4-12 hours, and then drying naturally to obtain a porous catalyst;

[0012] (4) After the product of step (3) is added to an organic amine solution and soaked for 1 to 6 hours, the boron nitride ceramic is taken out, washed with ethanol, dried, and stored in an oxygen-free environment to obtain an amino-modified supported metal catalyst.

[0013] The boron nitride ceramics described in the present invention include gas-pressed boron nitride ceramics and / or hot-pressed boron nitride ceramics.

[0014] Preferably, the boron nitride ceramic in step (1) is in granular or block form.

[0015] The acid used in the pickling in step (1) of the present invention includes one or more of HCl, H2SO4, and HNO3, preferably with a molar ratio of any two of the acids being 0.2 to 5:1. Pickling can activate the support surface while cleaning the surface, making it easier to functionalize.

[0016] As a preferred solution, the acid in step (1) is H2SO4 and / or HNO3, preferably the molar ratio of H2SO4:HCl is 0.2 to 3:1.

[0017] Preferably, the pickling temperature in step (1) is 40-80° C., and the pickling time is 2-6 hours, preferably 2-4 hours.

[0018] Preferably, the solvent used in step (2) is THF, and the amount used is suitable for immersing the boron nitride ceramic.

[0019] Preferably, the surfactant used in step (2) is selected from one or more of polyether F127 (Mn ~ 13000, Nantong Runfeng), F188 (Mn: 8000 ~ 10000, Haian Petrochemical), P123 (Mn ~ 5800, Shanghai Yien Chemical Technology), etc., and the amount used is 0.01 ~ 1wt% of the boron nitride ceramic in step (1).

[0020] Preferably, the pore-forming agent used in step (2) is one or more of urea pore-forming agent (Inokai, 99%), PMMA pore-forming agent (Kemai New Materials, 800nm), etc., and the amount used is 0.2-2wt% of the boron nitride ceramic in step (1).

[0021] Preferably, the organic iron used in step (2) comprises one or more of ferrous lactate, ferric citrate, ferric glycinate, and ferrocene.

[0022] Preferably, the organic aluminum used in step (2) comprises one or more of triethylaluminum, triisobutylaluminum, and diethylaluminum chloride.

[0023] Preferably, in step (2), the mass ratio of organic iron to organic aluminum is 0.1 to 5:1.

[0024] Preferably, in step (2), the total mass of organic iron and organic aluminum is 0.5 to 20% of the boron nitride ceramic in step (1).

[0025] Preferably, the temperature of step (3) is 150-240° C., and the reaction time is 2-6 hours.

[0026] The function of step (3) of the present invention is to solidify and form pores.

[0027] The function of step (4) of the present invention is grafting.

[0028] Preferably, the organic amine used in step (4) includes aliphatic amines (monomethylamine, ethylamine, trimethylamine, ethylenediamine, etc.), alcohol amines (ethanolamine, methyldiethanolamine, etc.), amides (caprolactam, etc.), alicyclic amines (isophoronediamine, etc.), aromatic amines (o-toluenediamine, m-phenylenediamine, etc.), naphthyl amines (naphthylamine, etc.), etc., and the amount used is 2 to 10 wt% of the boron nitride ceramic in step (1).

[0029] Preferably, the soaking time in step (4) is 4 to 6 hours.

[0030] A method for preparing tetramethylammonium methyl carbonate comprises the following steps: using the methylation reaction catalyst of the present invention, reacting trimethylamine (TMA) and dimethyl carbonate (DMC) at 70-150 DEG C.

[0031] The present invention uses boron nitride as a ceramic substrate as an example. By precipitating metal on the surface of the ceramic membrane, the metal sites are anchored under the action of polyether (polyether surfactants have excellent surface activity and adjustable HLB values). This patent preferably uses organic metals to provide active sites. By adjusting the steric hindrance between the transition metal and the long-chain hydrocarbon, a functionalization reaction of the C-H bond is achieved. Subsequently, organic amines are grafted onto the surface to form a catalytic surface with -N-Fe- functional groups on the surface of the boron nitride ceramic. The orbital hybridization between Fe-NC provides a unique catalytic effect. The anchoring of Fe by N is conducive to improving the single-atom dispersion of Fe, further enhancing the catalytic effect. At the same time, the addition of co-catalyst Al as a Lewis acid can adjust the selectivity and reaction rate of the reaction.

[0032] The catalyst has a simple synthesis process, uniform metal site distribution, large specific surface area, and high catalytic activity.

[0033] The boron nitride ceramic of the present invention has excellent catalytic performance and high selectivity. The selectivity of the decomposition product CO2 from DMC hydrolysis is low, which greatly improves the time and space benefits of TMAC. In addition, the catalyst structure is stable and acid and alkali resistant. As a heterogeneous catalyst, it is easy to separate and does not introduce impurities (especially metal impurities) into the system, and can maintain the stability of the catalytic performance for a long time. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described below through specific embodiments.

[0035] In the present invention, unless otherwise specified, the raw materials and equipment used can be purchased from the market or are commonly used in the art.

[0036] Unless otherwise specified, the methods in the embodiments are conventional methods in the art.

[0037] Example 1

[0038] (1) 100 g of silicon nitride ceramic (99%, Bio New Materials) was pickled (molar ratio of HCl:H2SO4=1:1) at a temperature of 40°C for 2 h; washed with water until neutral, and dried;

[0039] (2) The product of step (1) was immersed in 200 g of methanol (99.5%, Aladdin) solvent, and nitrogen atmosphere was passed through. Polyether F127 (1 g, Mn-13000, Nantong Runfeng) and urea pore former (99.5%, 2 g, Aladdin) were added, followed by ferrous lactate (5 g, 99%, Jiangsu Ruicheng Biotechnology) and triethylaluminum (5 g, 1 M, Aladdin). After reacting for 6 h, the mixture was taken out and dried;

[0040] (3) heating the product of step (2) to 240° C. for curing and pore formation, reacting for 6 hours, and then naturally drying to obtain a porous structure;

[0041] (4) Add trimethylamine methanol solution (25wt%, 200g, TCI) for soaking and grafting. After reacting for 6 hours, take out the boron nitride ceramic, wash and dry it with ethanol, and store it in an oxygen-free environment to obtain an amino-modified supported metal catalyst.

[0042] Example 2

[0043] (1) 100 g of silicon nitride ceramic (99%, Bio New Materials) was pickled (molar ratio of HCl:H2SO4=1:5) at a temperature of 60°C for 4 h; washed with water until neutral, and dried;

[0044] (2) The product of step (1) was immersed in 200 g of methanol (99.5%, Aladdin) solvent, and nitrogen atmosphere was passed through. Polyether F188 (0.5 g, Mn: 8000-10000, Haian Petrochemical) and PVB pore former (99%, 0.5 g, Aladdin) were added, followed by ferric citrate (0.02 g, Aladdin) and triisobutylaluminum (0.03 g, 95%, Jiangsu AIMOU Broadcasting and Electronic Materials). After reacting for 6 h, the mixture was taken out and dried;

[0045] (3) heating the product of step (2) to 180° C. for curing and pore formation, reacting for 4 hours, and then naturally drying to obtain a porous structure;

[0046] (4) Add triethanolamine methanol solution (25wt%, 200g, TCI) to soak the grafted material. After reacting for 4 hours, take out the boron nitride ceramic, wash and dry it with ethanol, and store it in an oxygen-free environment to obtain an amino-modified supported metal catalyst.

[0047] Example 3

[0048] (1) 100 g of silicon nitride ceramic (99%, Bio New Materials) was pickled (molar ratio of HCl:H2SO4=5:1) at a temperature of 60°C for 6 h; washed with water until neutral, and dried;

[0049] (2) The product of step (1) was immersed in 200 g of methanol (99.5%, Aladdin) solvent, and nitrogen atmosphere was passed through. Polyether F127 (0.01 g, Mn ~ 13000, Nantong Runfeng) and PVB pore former (99%, 2 g, Aladdin) were added, followed by ferric citrate (1.8 g, Aladdin) and diethylaluminum chloride (18 g, 99%, Jiangsu Aimou Broadcasting and Electronic Materials). After reacting for 3 h, the mixture was taken out and dried;

[0050] (3) heating the product of step (2) to 140° C. for curing and pore formation, reacting for 2 h, and then naturally drying to obtain a porous structure;

[0051] (4) Add trimethylamine methanol solution (25wt%, 200g, TCI) to soak the grafted material. After reacting for 4 hours, take out the boron nitride ceramic, wash and dry it with ethanol, and store it in an oxygen-free environment to obtain an amino-modified supported metal catalyst.

[0052] Example 4

[0053] (1) 100 g of molecular sieve (3A, Guangzhou Xinci Environmental Protection Materials Co., Ltd.) was acid-washed (molar ratio of HCl:H2SO4 = 2:1) at a temperature of 70°C for 5 h; washed with water until neutral, and dried;

[0054] (2) The product of step (1) was immersed in 200 g of methanol (99.5%, Aladdin) solvent, and nitrogen atmosphere was passed through. Polyether P123 (0.03 g, Mn-5800, Shanghai Yien Chemical Technology) and urea pore former (99.5%, 1 g, Aladdin) were added. Then, ferrocene (15 g, 98%, Aladdin) and triethylaluminum (3 g, Aladdin) were added. After reacting for 4 h, the mixture was taken out and dried;

[0055] (3) heating the product of step (2) to 150° C. for curing and pore formation, reacting for 5 h, and then naturally drying to obtain a porous structure;

[0056] (4) Add trimethylamine methanol solution (25wt%, 200g, TCI) to soak the grafted material. After reacting for 5 hours, take out the boron nitride ceramic, wash and dry it with ethanol, and store it in an oxygen-free environment to obtain an amino-modified supported metal catalyst.

[0057] Example 5

[0058] (1) 100 g of silicon nitride ceramic (99%, Bio New Materials) was pickled (molar ratio of HCl:H2SO4=3:1) at 80°C for 3 h; washed with water until neutral, and dried;

[0059] (2) The product of step (1) was immersed in 200 g of methanol (99.5%, Aladdin) solvent, and nitrogen atmosphere was passed through. Polyether F188 (0.3 g, Mn: 8000-10000, Haian Petrochemical) and urea pore former (99.5%, 2 g, Aladdin) were added, followed by ferrous lactate (0.5 g, 99%, Jiangsu Ruicheng Biotechnology) and triisobutylaluminum (0.6 g, Jiangsu Aimou Broadcasting and Electronic Materials). After reacting for 6 h, the mixture was taken out and dried;

[0060] (3) heating the product of step (2) to 200° C. for solidification and pore formation, reacting for 6 h, and then naturally drying to obtain a porous structure;

[0061] (4) Add triethanolamine methanol solution (25wt%, 200g, TCI) to soak the grafted material. After reacting for 7 hours, take out the boron nitride ceramic, wash and dry it with ethanol, and store it in an oxygen-free environment to obtain an amino-modified supported metal catalyst.

[0062] Comparative Example 1

[0063] Except for ferrous lactate (10 g) and triisobutylaluminum (0 g), the rest is the same as Example 5.

[0064] Comparative Example 2

[0065] Except for ferrocene (0 g) and triethylaluminum (5 g), the rest is the same as Example 4.

[0066] Comparative Example 3

[0067] The same procedures as in Example 3 were followed except that no amine was used for modification.

[0068] Comparative Example 4

[0069] Except that the polyether surfactant is not used, the rest is the same as Example 1.

[0070] Comparative Example 5

[0071] Except that the iron salt is replaced by FeCl3, the rest is the same as Example 1.

[0072] Comparative Example 6

[0073] Except that the aluminum salt is replaced by CuSO4, the rest is the same as Example 2.

[0074] Comparative Example 7

[0075] The product obtained in step (1) of Example 1 was directly used as a catalyst.

[0076] The catalysts prepared in Examples 1-5 and Comparative Examples 1-5 were evaluated for their methylation performance. The reaction evaluated was the reaction of trimethylamine (TMA) and dimethyl carbonate (DMC) to produce tetramethylammonium methyl carbonate. The ratio of TMA:DMC was 1:1, the reaction temperature was 120°C, and the reaction time was 1 hour. The results (based on DMC) are shown in Table 1 below:

[0077] Table 1

[0078]

Claims

1. A method for preparing a methylation reaction catalyst, comprising the following steps: (1) pickling the boron nitride ceramic, washing with water until neutral, and drying; (2) Under nitrogen protection, soaking the product of step (1) in a solvent, adding a surfactant and a pore-forming agent, and then adding organic iron and organic aluminum, reacting for 2 to 8 hours, and drying to obtain a metal-loaded catalyst; (3) heating the product of step (2) to 120-240° C. for 4-12 hours, and then drying naturally to obtain a porous catalyst; (4) After the product of step (3) is added to an organic amine solution and soaked for 1 to 6 hours, the boron nitride ceramic is taken out, washed with ethanol, dried, and stored in an oxygen-free environment to obtain an amino-modified supported metal catalyst.

2. The method according to claim 1, characterized in that The acid used for pickling in step (1) includes one or more of HCl, H2SO4, and HNO3.

3. The method according to claim 1, characterized in that The acid used for pickling in step (1) has a molar ratio of H2SO4:HCl of 0.2 to 3:

1.

4. The method according to claim 1, wherein The pickling temperature in step (1) is 40-80° C., and the pickling time is 2-6 hours.

5. The method according to claim 1, wherein The pickling time in step (1) is 2 to 4 hours.

6. The method according to claim 1, characterized in that The surfactant used in step (2) is selected from one or more of polyether F127, polyether F188, and polyether P123, and the amount used is 0.01 to 1 wt% of the boron nitride ceramic in step (1).

7. The method according to claim 1, characterized in that The pore-forming agent used in step (2) is selected from one or more of urea pore-forming agent and PMMA pore-forming agent, and the amount used is 0.2-2 wt% of the boron nitride ceramic in step (1).

8. The method according to claim 1, characterized in that The organic iron used in step (2) comprises one or more of ferrous lactate, ferric citrate, ferric glycinate, and ferrocene.

9. The method according to claim 1, characterized in that The organic aluminum used in step (2) comprises one or more of triethylaluminum, triisobutylaluminum, and diethylaluminum chloride.

10. The method according to claim 1, characterized in that In the step (2), the mass ratio of organic iron to organic aluminum is 0.1 to 5:1; and the total mass of the organic iron and organic aluminum is 0.5 to 20% of the boron nitride ceramic in step (1).

11. The method according to claim 1, wherein The organic amine used in step (4) includes one or more of aliphatic amines, alcohol amines, amides, alicyclic amines, and aromatic amines.

12. A method for preparing tetramethylammonium methyl carbonate, comprising the following steps: The methylation reaction catalyst prepared by the method according to any one of claims 1 to 11 is used, and trimethylamine and dimethyl carbonate are reacted at 70 to 150° C.

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