CN104785298B - Solid base catalyst taking metal organic framework material as carrier, preparation method and application thereof - Google Patents

Abstract

The invention discloses a solid base catalyst with a metal organic framework material as a carrier, which can be used as a catalyst for transesterification. The solid base catalyst is prepared by using a metal-organic framework material as a carrier through methods such as wet impregnation and heat treatment, and can catalyze transesterification under mild conditions to synthesize dimethyl carbonate. The solid base catalyst with a metal organic framework material as a carrier of the present invention is composed of a metal organic framework material carrier and an alkaline component, the alkaline component is introduced by an alkali precursor, and the alkali precursor and the metal organic framework The mass ratio of materials is 0.01-0.5:1.

Description

A kind of solid base catalyst with metal organic framework material as carrier, preparation method and its application

technical field

The invention relates to a catalyst, a preparation method and its application, more specifically to a solid base catalyst with a metal organic framework material as a carrier, a preparation method and its application.

Background technique

Solid base catalysts are widely used in the production of petrochemicals and fine chemicals. They can catalyze various reactions under relatively mild conditions. They have high activity, good selectivity, mild reaction conditions, easy separation of products, and recyclability. Take advantage of many other advantages. Especially in the production process, the reaction process can be continuous, the production capacity of the equipment can be enhanced, and the application prospect is very broad.

In recent years, metal-organic frameworks have attracted extensive research as a novel organic-inorganic hybrid porous material. This kind of material is a porous material formed by the self-assembly of different metal ions and organic ligands, which has some special structural characteristics and very strong designability and adjustability. These unique advantages make metal-organic framework materials have very good application prospects in the fields of gas storage, adsorption separation and catalysis. Specific to the field of catalysis, in many industrial catalytic processes, metal-organic framework materials that can be applied in the field of catalysis can be divided into three types: (1) metal-organic framework materials with metal active sites; (2) metal-organic framework materials with reactive activity Functional metal organic framework materials; (3) metal organic framework materials as catalyst supports or as molecular reactors. The materials of institute Lavoisier frameworks (MILs for short) first synthesized by the research group of Professor Férey of the University of Versailles in France can be used as an ideal load due to its large specific surface area and stable structural characteristics. catalyst support.

Dimethyl carbonate (DMC) is a green and environmentally friendly chemical product that has attracted much attention at home and abroad. Because its structure contains methoxy and carbonyl groups, it is expected to replace highly toxic or carcinogenic substances such as phosgene for carbonylation and methylation. And transesterification reactions to prepare many important chemical products. The transesterification method is an important method for the synthesis of dimethyl carbonate, and its mild reaction conditions, non-toxic process and high selectivity have become a method with great application prospects. Solid base catalyst is the core technology for the synthesis of DMC by transesterification. Therefore, the development of new and efficient solid base catalyst materials has attracted much attention.

Based on the above problems, it is of great practical value to prepare solid base catalysts supported by metal-organic framework materials and apply them to the synthesis of dimethyl carbonate by transesterification.

Contents of the invention

The object of the present invention is to provide a solid base catalyst with a metal organic framework material as a carrier, which can be used as a catalyst for transesterification. The solid base catalyst is prepared by using a metal-organic framework material as a carrier through methods such as wet impregnation and heat treatment, and can catalyze transesterification under mild conditions to synthesize dimethyl carbonate.

Another object of the present invention is to provide a preparation method of the above-mentioned solid base catalyst; meanwhile, the present invention also provides the application of the solid base catalyst in transesterification.

The purpose of the present invention is achieved through the following technical solutions:

The solid base catalyst with a metal organic framework material as a carrier of the present invention is composed of a metal organic framework material carrier and an alkaline component, the alkaline component is introduced by an alkali precursor, and the alkali precursor and the metal organic framework The mass ratio of materials is 0.01-0.5:1.

The above-mentioned solid base catalyst of the present invention, its further technical scheme is that described metal organic framework material carrier is model is MIL-100, MIL-101, MIL-53, MIL-47, MIL-96, MIL-110 or MIL -68 to Vasil skeleton material.

The above-mentioned solid alkali catalyst of the present invention, its further technical scheme can also be that described alkali precursor is lithium nitrate, sodium nitrate, potassium nitrate, rubidium nitrate, cesium nitrate, magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate and One or several components of the corresponding acetate.

The preparation method of above-mentioned solid alkali catalyst of the present invention, it comprises the following steps:

(1) Using the wet impregnation method, first dissolve the alkali precursor in deionized water, add the metal-organic framework material, stir at room temperature for 12-24 hours, evaporate to dryness in a water bath at 50-80°C, and place in an oven at 80-100°C Dry for 4-8 hours to obtain the mixture;

(2) activating the mixture prepared in step (1) in an inert gas atmosphere by heat treatment for 1 to 4 hours to generate basic sites to obtain a solid base catalyst supported by metal-organic framework materials.

The preparation method of the above-mentioned solid alkali catalyst of the present invention, its further technical scheme is that described alkali precursor is lithium nitrate, sodium nitrate, potassium nitrate, rubidium nitrate, cesium nitrate, magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate and one or more of the corresponding acetates, the mass ratio of the alkali precursor to the metal-organic framework material is 0.01-0.5:1.

The preparation method of the above-mentioned solid base catalyst of the present invention, its further technical scheme can also be that described metal-organic framework material carrier is model is MIL-100, MIL-101, MIL-53, MIL-47, MIL-96, Levasher frame material of MIL-110 or MIL-68.

The further technical solution of the above-mentioned method for preparing the solid base catalyst of the present invention may be that the inert gas is helium, argon or nitrogen; the activation temperature of the heat treatment method is 200-500°C.

The above-mentioned solid base catalyst of the present invention can be applied in the transesterification reaction; The further technical scheme is the application in the preparation of dimethyl carbonate with ethylene carbonate and methanol as raw materials.

The above-mentioned solid base catalyst of the present invention mainly comprises the following steps in the application of preparing dimethyl carbonate with ethylene carbonate and methyl alcohol as raw material: ethylene carbonate, methyl alcohol and solid base catalyst are put into three-necked flask, ethylene carbonate and methyl alcohol The molar ratio is 1:5, the amount of catalyst used is 0.2-5% of the raw material methanol mass, the reaction temperature is 60-80°C, the pressure is normal pressure, the reaction is 0.5-4h under reflux and stirring conditions, and centrifuged to obtain dimethyl carbonate.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The solid base catalyst prepared by the present invention adopts the metal-organic framework material (MILs) as the carrier for the first time, and activates the base precursor loaded on the carrier by heat treatment to prepare a new type of solid base catalyst. The method combines the characteristics of the higher specific surface area and the larger pore structure of the metal-organic framework material to achieve highly dispersed alkali active sites on the carrier, and at the same time, the activation temperature is lower, which improves the catalytic activity.

(2) The present invention provides a simple and energy-saving catalyst preparation method. On the one hand, due to the high charge density that can be formed by the abundant metal ions in the channels of metal-organic framework materials, the decomposition temperature of the alkali precursor can be greatly reduced, thereby reducing the cumbersome steps in the catalyst preparation process; on the other hand, the alkali precursor The reduction of decomposition temperature can reduce the consumption of energy, thereby also realizing the effect of energy saving.

(3) The solid base catalyst prepared by the present invention can catalyze the transesterification reaction, especially the synthesis of dimethyl carbonate, in a relatively mild environment, with ideal catalytic effect and low operating cost.

detailed description

The present invention is illustrated with the following specific implementation examples, but the present invention is not limited to the following examples. Within the scope of not departing from the purpose described before and after, all changes and implementations are included in the technical scope of the present invention.

Example 1

Weigh 0.2g of NaNO ₃ and dissolve it in deionized water, add 0.8g of metal-organic framework material MIL-100 under stirring state, stir at room temperature for 24h, place in 80°C water bath, evaporate to dryness, and then place in 100°C oven After drying for 8 hours, the obtained sample was placed in a U-shaped tube and activated with nitrogen gas at 350°C for 2 hours to decompose NaNO ₃ .

16g of methanol, 8.7g of ethylene carbonate and 0.08g of catalyst were added to the flask, and stirred at 65°C for 4 hours under normal pressure. The supernatant was obtained by centrifugation and analyzed by gas chromatography. The yield of DMC was 32.0%.

Example 2

Weigh 0.1g of LiNO ₃ and dissolve it in deionized water, add 0.9g of metal-organic framework material MIL-96 under stirring, stir at room temperature for 24h, place it in a water bath at 80°C and evaporate to dryness, and then place it in an oven at 100°C After drying for 8 hours, the obtained sample was placed in a U-shaped tube and activated with nitrogen gas at 300°C for 2 hours to decompose LiNO ₃ .

16g of methanol, 8.7g of ethylene carbonate and 0.08g of catalyst were added to the flask, and stirred at 65°C for 4 hours under normal pressure. The supernatant was obtained by centrifugation and analyzed by gas chromatography. The yield of DMC was 20.1%.

Example 3

Weigh 0.38g of Mg(CH ₃ COO) ₂ ·4H ₂ O and dissolve in deionized water, add 0.75g of metal-organic framework material MIL-68 under stirring state, stir at room temperature for 24h and place in 80°C water bath Evaporate to dryness, and then dry in an oven at 100°C for 8 hours, place the obtained sample in a U-shaped tube and blow nitrogen into it to activate at 400°C for 2 hours, so as to decompose Mg(CH ₃ COO) ₂ .

16g of methanol, 8.7g of ethylene carbonate and 0.08g of catalyst were added into the flask, and stirred at 65°C for 4h under normal pressure. The supernatant was obtained by centrifugation and analyzed by gas chromatography. The yield of DMC was 35.2%.

Example 4

Weigh 0.33g of Ca(CH ₃ COO) ₂ ·H ₂ O and dissolve it in deionized water, add 0.7g of metal-organic framework material MIL-101 under stirring, stir at room temperature for 24h and place in 80°C water bath Evaporate to dryness, then dry in an oven at 100°C for 8h, place the obtained sample in a U-shaped tube and blow nitrogen into it and activate at 250°C for 2h to decompose Ca(CH ₃ COO) ₂ .

16g of methanol, 8.7g of ethylene carbonate and 0.08g of catalyst were added into the flask, and stirred at 65°C for 4h under normal pressure. The supernatant was obtained by centrifugation and analyzed by gas chromatography. The yield of DMC was 36.7%.

Example 5

Weigh 0.2g of CsNO ₃ and dissolve it in deionized water, add 0.8g of metal-organic framework material MIL-110 under stirring state, stir at room temperature for 24h, evaporate to dryness in 80°C water bath, and then place in 100°C oven After drying for 8 hours, the obtained sample was placed in a U-shaped tube and activated with nitrogen gas at 400°C for 2 hours to decompose CsNO ₃ .

16g of methanol, 8.7g of ethylene carbonate and 0.08g of catalyst were added to the flask, and stirred at 65°C for 4 hours under normal pressure. The supernatant was obtained by centrifugation and analyzed by gas chromatography. The yield of DMC was 22.5%.

Example 6

Weigh 0.2g of KNO ₃ and dissolve it in deionized water, add 0.8g of metal-organic framework material MIL-100 under stirring state, stir at room temperature for 24h, place in 80°C water bath, evaporate to dryness, and then place in 100°C oven After drying for 8 hours, the obtained sample was placed in a U-shaped tube and activated with nitrogen gas at 400°C for 2 hours to decompose KNO ₃ .

16g of methanol, 8.7g of ethylene carbonate and 0.08g of catalyst were added into the flask, and stirred at 65°C for 4h under normal pressure. The supernatant was obtained by centrifugation and analyzed by gas chromatography. The yield of DMC was 29.2%.

Example 7

Weigh 0.25g of Ca(NO ₃ ) ₂ and dissolve it in deionized water, add 0.75g of metal-organic framework material MIL-53 under stirring, stir at room temperature for 24h, place in 80°C water bath and evaporate to dryness, and then After drying in an oven at 100°C for 8 hours, the obtained sample was placed in a U-shaped tube and activated with nitrogen gas at 350°C for 2 hours to decompose Ca(NO ₃ ) ₂ .

16g of methanol, 8.7g of ethylene carbonate and 0.08g of catalyst were added into the flask, and stirred at 65°C for 4h under normal pressure. The supernatant was obtained by centrifugation and analyzed by gas chromatography. The yield of DMC was 31.3%.

Example 8

Weigh 0.31g of CH ₃ COOLi·2H ₂ O and dissolve it in deionized water, add 0.8g of metal-organic framework material MIL-47 under stirring, stir at room temperature for 24h, place in 80°C water bath and evaporate to dryness, then Dry in an oven at 100°C for 8 hours, place the obtained sample in a U-shaped tube and blow nitrogen into it to activate at 300°C for 2 hours, so as to decompose CH ₃ COOLi.

16g of methanol, 8.7g of ethylene carbonate and 0.08g of catalyst were added into the flask, and stirred at 65°C for 4h under normal pressure. The supernatant was obtained by centrifugation and analyzed by gas chromatography. The yield of DMC was 28.4%.

Example 9

Weigh 0.4g of Sr(NO ₃ ) ₂ and dissolve it in deionized water, add 0.6g of metal-organic framework material MIL-68 under stirring, stir at room temperature for 24h, place in 80°C water bath and evaporate to dryness, and then Dry in an oven at 100°C for 8 hours, place the obtained sample in a U-shaped tube and blow nitrogen into it to activate at 400°C for 2 hours, so as to decompose Sr(NO ₃ ) ₂ .

16g of methanol, 8.7g of ethylene carbonate and 0.08g of catalyst were added into the flask, and stirred at 65°C for 4 hours under normal pressure. The supernatant was obtained by centrifugation and analyzed by gas chromatography. The yield of DMC was 30.3%.

Example 10

Weigh 0.1g of CH ₃ COOK and dissolve it in deionized water, add 0.9g of metal-organic framework material MIL-101 under stirring, stir at room temperature for 24h, put it in an 80°C water bath, evaporate to dryness, and then place it in an oven at 100°C Dry in the oven for 8 hours, place the obtained sample in a U-shaped tube and pass through nitrogen to activate at 450°C for 2 hours, so as to decompose CH ₃ COOK.

16g of methanol, 8.7g of ethylene carbonate and 0.08g of catalyst were added to the flask, and stirred at 65°C for 4h under normal pressure. The supernatant was obtained by centrifugation and analyzed by gas chromatography. The yield of DMC was 32.6%.

Example 11

Weigh 0.17g of Mg(NO ₃ ) ₂ ·6H ₂ O and dissolve it in deionized water, add 0.9g of metal-organic framework material MIL-96 under stirring, stir at room temperature for 24h, place in 80°C water bath to evaporate After drying, it was dried in an oven at 100°C for 8 hours, and the obtained sample was placed in a U-shaped tube and activated with nitrogen gas at 350°C for 2 hours to decompose Mg(NO ₃ ) ₂ .

16g of methanol, 8.7g of ethylene carbonate and 0.08g of catalyst were added to the flask, and stirred at 65°C for 4h under normal pressure. The supernatant was obtained by centrifugation and analyzed by gas chromatography. The yield of DMC was 21.3%.

Example 12

Weigh 0.33g of CH ₃ COONa·3H ₂ O and dissolve it in deionized water, add 0.8g of metal-organic framework material MIL-96 under stirring, stir at room temperature for 24h, place it in a water bath at 80°C and evaporate to dryness, then Dry in an oven at 100°C for 8h, place the obtained sample in a U-shaped tube and blow nitrogen into it to activate at 300°C for 2h, so as to decompose CH ₃ COONa.

16g of methanol, 8.7g of ethylene carbonate and 0.08g of catalyst were added to the flask, and stirred at 65°C for 4 hours under normal pressure. The supernatant was obtained by centrifugation and analyzed by gas chromatography. The yield of DMC was 23.7%.

Claims (9)

1. a kind of solid base catalyst with metal-organic framework materials as carrier, it is characterised in that the solid base catalyst be by Metal-organic framework materials carrier and basic component are constituted, and described basic component is introduced by alkali presoma, alkali presoma and gold The mass ratio for belonging to organic framework material is 0.01~0.5:1；Described metal-organic framework materials carrier is model MIL- 100th, MIL-101, MIL-53, MIL-47, MIL-96, MIL-110 or MIL-68 carry out Wa Xier framework materials；Described solid The preparation method of base catalyst is comprised the following steps：

(1) wet impregnation method is used, first by the dissolving of alkali presoma in deionized water, metal-organic framework materials is added, at room temperature After 12~24h of stirring, it is evaporated in 50~80 DEG C of water-baths, 4~8h is dried in 80~100 DEG C of baking ovens, obtains mixture；

(2) heat treating process is used, in atmosphere of inert gases, mixture obtained in activation step (1), soak time is 1~4h, Activation temperature is 200~500 DEG C, is allowed to produce basic sites, obtains the catalyzed by solid base with metal-organic framework materials as carrier Agent.

2. solid base catalyst according to claim 1, it is characterised in that described alkali presoma is lithium nitrate, nitric acid One kind or several in sodium, potassium nitrate, rubidium nitrate, cesium nitrate, magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate and corresponding acetate Plant composition.

3. the preparation method of a kind of solid base catalyst as described in claim 1-2 is any, it is characterised in that including following step Suddenly：

(1) wet impregnation method is used, first by the dissolving of alkali presoma in deionized water, metal-organic framework materials is added, at room temperature After 12~24h of stirring, it is evaporated in 50~80 DEG C of water-baths, 4~8h is dried in 80~100 DEG C of baking ovens, obtains mixture；

(2) heat treating process is used, in atmosphere of inert gases, mixture obtained in activation step (1), soak time is 1~4h, Activation temperature is 200~500 DEG C, is allowed to produce basic sites, obtains the catalyzed by solid base with metal-organic framework materials as carrier Agent.

4. the preparation method of solid base catalyst according to claim 3, it is characterised in that described alkali presoma is nitre In sour lithium, sodium nitrate, potassium nitrate, rubidium nitrate, cesium nitrate, magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate and corresponding acetate One or more compositions, the mass ratio of alkali presoma and metal-organic framework materials is 0.01~0.5:1.

5. the preparation method of the solid base catalyst according to claim 3 or 4, it is characterised in that the organic bone of described metal Frame material carrier be model MIL-100, MIL-101, MIL-53, MIL-47, MIL-96, MIL-110 or MIL-68 come watt Xi Er framework materials.

6. the preparation method of solid base catalyst according to claim 3, it is characterised in that described inert gas is helium Gas, argon gas or nitrogen.

7. a kind of application of the solid base catalyst in ester exchange reaction as described in claim 1-2 is any.

8. application of the solid base catalyst according to claim 7 in ester exchange reaction, it is characterised in that be with carbon Vinyl acetate and methyl alcohol prepare the application in dimethyl carbonate for raw material.

9. application of the solid base catalyst according to claim 8 in ester exchange reaction, it is characterised in that it is described Mainly included the following steps that with the application that ethylene carbonate and methyl alcohol prepare dimethyl carbonate as raw material：By ethylene carbonate, first Alcohol and solid base catalyst are put into three-neck flask, and the mol ratio of ethylene carbonate and methyl alcohol is 1:5, catalyst amount is raw material The 0.2~5% of methanol quality, reaction temperature is 60~80 DEG C, and pressure is normal pressure, and 0.5~4h is reacted under the conditions of being refluxed, from The isolated dimethyl carbonate of the heart.