阅读说明：本技术 多金属氧簇-石墨烯泡沫可压缩催化剂的制备方法及其应用 (Preparation method and application of polymetallic oxygen cluster-graphene foam compressible catalyst ) 是由 迟瑛楠 荆晓婷 于 2020-04-22 设计创作，主要内容包括：本发明公开了一种多金属氧簇-石墨烯泡沫可压缩催化剂的制备方法及合成催化剂在催化生物柴油制备方面的应用,属于催化剂材料制备技术领域和催化领域。所述方法为(1)合成多金属氧簇-石墨烯泡沫自组装可压缩催化剂H<Sub>3</Sub>PW<Sub>12</Sub>O<Sub>40</Sub>@Graphene Foam(简称PW<Sub>12</Sub>@GF)；(2)长碳链脂肪酸与短链醇在可压缩催化剂作用下经过酯化反应生成相应酯类化合物。本发明所述方法中制备并使用的可压缩催化剂可以有效地吸附反应物,并且催化结束后,通过压缩催化剂可以实现反应产物与催化剂的快速分离。在整个催化过程中无需机械搅拌,节约能源,且制备的可压缩催化剂可重复使用。(The invention discloses a preparation method of a polymetallic oxygen cluster-graphene foam compressible catalyst and application of a synthetic catalyst in preparation of catalytic biodiesel, and belongs to the technical field of catalyst material preparation and the field of catalysis. The method comprises (1) synthesizing a polymetallic oxygen cluster-graphene foam self-assembly compressible catalyst H 3 PW 12 O 40 @ Graphene Foam (abbreviated as PW) 12 @ GF); (2) the long-carbon-chain fatty acid and the short-chain alcohol are subjected to esterification reaction under the action of a compressible catalyst to generate a corresponding ester compound. The compressible catalyst prepared and used in the method can effectively adsorb reactants, and after the catalysis is finished, the reaction product and the catalyst can be quickly separated by compressing the catalyst. Mechanical stirring is not needed in the whole catalysis process, energy is saved, and the prepared compressible catalyst can be repeatedly used.)

1. A preparation method of a polymetallic oxygen cluster-graphene foam compressible catalyst is characterized by comprising the following specific steps:

adding graphene oxide, phosphotungstic acid and tween-80 into a beaker, violently stirring at normal temperature, and carrying out freeze drying treatment for 3 days; at Ar/H₂After annealing treatment in the atmosphere, the substrate was immersed in a methanol solution to remove the unloaded PW₁₂(ii) a Drying at 100 ℃ to obtain the phosphotungstic acid-graphene foam compressible catalyst PW₁₂@GF。

2. The method of claim 1, wherein: and (3) graphene oxide: phosphotungstic acid: the mass ratio of the Tween-80 is 1:1: 1.5.

3. The method of claim 1, wherein: the vigorous stirring was performed with a magnetic stirrer at 1000rpm for 10min to change the solution from brown to yellow.

4. The method of claim 1, wherein: the annealing treatment is performed at Ar/H₂Annealing at 200 ℃ in an atmosphereAnd (5) performing fire treatment for 2-6 h.

5. A compressible catalyst PW prepared according to claim 1₁₂The application of @ GF in the preparation of catalytic biodiesel is characterized in that: dropwise adding the reaction solution into a catalyst PW₁₂The reaction solution in the @ GF is completely absorbed by the catalyst and reacts for 6 hours at the temperature of 60 ℃ to obtain the product.

6. Use according to claim 5, characterized in that: mechanical stirring is not needed in the whole catalysis process.

7. Use according to claim 5, characterized in that: the catalyst can effectively adsorb reactants, and after the catalysis is finished, the rapid separation of reaction products and the catalyst can be realized by compressing the catalyst.

Technical Field

The invention belongs to the technical field of catalyst material preparation and the field of catalysis, and relates to a preparation technology of a polymetallic oxygen cluster-graphene foam compressible catalyst and application of the catalyst in preparation of catalytic biodiesel.

Background

In order to meet the ever-increasing energy demand, the preparation of biodiesel is an effective solution. Compared with the traditional petroleum diesel, the biodiesel is a renewable, biodegradable and environment-friendly energy source. Usually, vegetable oil, animal fat or free fatty acid is used as raw material and synthesized by esterification or ester exchange reaction. Therefore, the key to catalyst design is how to achieve high conversion under mild conditions. To date, a variety of catalysts, including acids, bases, and biological enzymes, have been used in the production of biodiesel. Among these, acid-catalyzed esterification has attracted considerable attention due to its low cost and the lack of saponification problems during the catalysis. Commonly used acid catalysts are strong bronsted acids such as sulfuric acid, hydrochloric acid, phosphoric acid and organic sulfonic acids. However, these liquid acid catalysts are often highly corrosive and may not be recycled in the catalytic process.

Polyoxometalates (POMs) are a well-known class of anionic metal-oxygen clusters having a variety of structures and excellent properties. POM is widely used as a green solid acid catalyst due to its tunable bronsted acidity and good thermal stability. With conventional mineral acids (e.g. H)₂SO₄，HNO₃) Compared with POM, POM is less corrosive, and side reactions such as sulfonation or nitration cannot occur in the catalysis process. However, POM has a high solubility in polar solvents and a very small surface area, which makes it unusable as a heterogeneous catalyst. Therefore, in order to achieve heterogeneous phase, POM generally needs to be immobilized on a functional support having a high surface area. Currently, a variety of supports have been used in the production of biodiesel, including metal oxides, clays, silica, zeolites, carbon, and Metal Organic Frameworks (MOFs).

However, most of the supported POM is a powder catalyst, so that mechanical stirring is required in the catalytic process, and energy is consumed; and after the catalytic reaction is finished, the separation of the catalyst and the product also needs time-consuming and labor-consuming operation steps such as centrifugation, filtration, washing and the like, which is not beneficial to industrial large-scale mass production.

Based on the current state of development in this field, and according to the potential application requirements, it is necessary to develop a compressible monolithic catalyst. The invention prepares the compressible monolithic catalyst by loading the polyoxometalate on a Graphene Foam (GF) carrier with excellent elasticity. It can effectively adsorb reactant, and can convert it into target product by means of fixed active site, and has no need of stirring in the whole catalytic process. Importantly, rapid separation of the reaction products from the catalyst can be achieved by compressing the catalyst.

Disclosure of Invention

Aiming at the defects of the existing method, the invention aims to provide a preparation method for synthesizing a polymetallic oxygen cluster-graphene foam compressible catalyst. The polymetallic oxygen cluster-graphene foam compressible catalyst has elasticity, can be used for preparing biodiesel, and can effectively solve the problems of quick separation of the catalyst and reaction products and the like.

The purpose of the invention is realized by the following technical scheme:

(1) phosphotungstic acid-graphene foam compressible catalyst PW₁₂Preparation of @ GF

The phosphotungstic acid-graphene foam compressible catalyst PW₁₂The preparation method of @ GF comprises the steps of adding graphene oxide, phosphotungstic acid and tween-80 into a beaker, violently stirring at normal temperature, and carrying out freeze drying treatment for 3 days. Then, at Ar/H₂After annealing treatment in the atmosphere, immersing the substrate in a methanol solution to remove the unloaded PW₁₂. Finally, drying at 100 ℃.

In the above preparation scheme, a preferable scheme is that the mass ratio of the raw materials is graphene oxide: phosphotungstic acid: tween-80 is 1:1: 1.5.

In the above-mentioned preparation, it is preferred that the solution is changed from brown to yellow by vigorous stirring with a magnetic stirrer at 1000rpm for 10 min.

Of the above-mentioned preparation schemes, the preferred scheme is that in Ar/H₂Annealing treatment is carried out for 4h at 200 ℃ under the atmosphere.

(2) Phosphotungstic acid-graphene foam compressible catalyst PW₁₂Preparation of @ GF catalyzed biodiesel

Dropwise adding the reaction solution into a catalyst PW₁₂The reaction solution in the @ GF is completely absorbed by the catalyst and reacts for 6 hours at the temperature of 60 ℃ to obtain the product.

Has the advantages that:

(1) the invention synthesizes the compressible elastic polymetallic oxygen cluster-graphene foam catalyst and uses the catalyst in the preparation of biodiesel.

(2) The catalyst provided by the invention has lipophilicity due to the carrier graphene foam, so that the catalyst is beneficial to contact with an organic substrate, and the catalytic activity is improved.

(3) The catalyst is an integral block catalyst, and mechanical stirring is not needed in the catalysis process, so that the energy is saved.

(4) The catalyst can effectively adsorb reactants, and after the catalysis is finished, the rapid separation of reaction products and the catalyst can be realized by compressing the catalyst, the time-consuming and labor-consuming separation steps such as traditional washing, centrifugation and the like are not needed, and the method is favorable for industrial large-scale production.

Drawings

FIG. 1 is a schematic diagram of the catalyst of the present invention for producing biodiesel.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, but is not limited thereto.

The main reagent information mentioned in the following examples is shown in table 1; the main instrument and equipment information is shown in table 2.

TABLE 1

TABLE 2