阅读说明：本技术 一种HRP/Co3O4@ZIF-8复合催化剂及其制备方法 (HRP/Co3O4@ ZIF-8 composite catalyst and preparation method thereof ) 是由 张国亮 李畅 于 2019-08-29 设计创作，主要内容包括：本发明公开了一种HRP/Co_3O_4@ZIF-8复合催化剂及其制备方法,所述的制备方法为：将四水合乙酸钴溶于乙醇溶剂中,然后加入氨水,置于高压反应釜中,在120～150℃条件下反应3～6h,得到Co_3O_4纳米粒子分散到去离子水中得到Co_3O_4纳米粒子的分散液,然后向Co_3O_4纳米粒子的分散液中加入聚乙烯吡咯烷酮,搅拌6～12h,得到改性的Co_3O_4纳米粒子；将二水合乙酸锌溶于去离子水中,得到浓度为0.1～0.2mol/L的二水合乙酸锌水溶液；将二甲基咪唑溶于去离子水中,得到浓度为0.4～0.8mol/L的二甲基咪唑水溶液；将HRP与改性的Co_3O_4纳米粒子一起加入到二甲基咪唑水溶液中,再加入二水合乙酸锌水溶液,置于0～4℃条件下反应12～h,得到HRP/Co_3O_4@ZIF-8复合催化剂。本发明所述的HRP/Co_3O_4@ZIF-8复合催化剂可应用于邻苯二胺的催化转化。(The invention discloses an HRP/Co3O4@ ZIF-8 composite catalyst and a preparation method thereof, wherein the preparation method comprises the following steps: dissolving cobalt acetate tetrahydrate in an ethanol solvent, adding ammonia water, placing the mixture in a high-pressure reaction kettle, reacting for 3-6 hours at 120-150 ℃ to obtain Co3O4 nanoparticles, dispersing the Co3O4 nanoparticles in deionized water to obtain a dispersion liquid of Co3O4 nanoparticles, adding polyvinylpyrrolidone into the dispersion liquid of the Co3O4 nanoparticles, and stirring for 6-12 hours to obtain modified Co3O4 nanoparticles; dissolving zinc acetate dihydrate in deionized water to obtain a zinc acetate dihydrate water solution with the concentration of 0.1-0.2 mol/L; dissolving dimethyl imidazole in deionized water to obtain a dimethyl imidazole aqueous solution with the concentration of 0.4-0.8 mol/L; adding HRP and modified Co3O4 nanoparticles into a dimethyl imidazole aqueous solution, adding a zinc acetate dihydrate aqueous solution, and reacting at 0-4 ℃ for 12-h to obtain the HRP/Co3O4@ ZIF-8 composite catalyst. The HRP/Co3O4@ ZIF-8 composite catalyst can be applied to catalytic conversion of O-phenylenediamine.)

1. An HRP/Co3O4@ ZIF-8 composite catalyst is characterized in that: the composite catalyst is prepared by the following method:

(1) Dissolving cobalt acetate tetrahydrate in an ethanol solvent, carrying out ultrasonic dissolution, adding 25% ammonia water by mass while carrying out vigorous stirring, fully stirring, placing in a high-pressure reaction kettle, reacting for 3-6 h at 120-150 ℃, washing and drying the obtained reaction solution to obtain Co3O4 nanoparticles; the volume dosage of the ethanol solvent is 50-60 mL/g calculated by the mass of cobalt acetate tetrahydrate; the volume usage of the ammonia water with the mass fraction of 25% is 5-15 mL/g based on the mass of the cobalt acetate tetrahydrate;

(2) Dispersing the Co3O4 nanoparticles prepared in the step (1) into deionized water to obtain a dispersion liquid of Co3O4 nanoparticles, adding polyvinylpyrrolidone into the dispersion liquid of the Co3O4 nanoparticles for ultrasonic dispersion, stirring for 6-12 h to obtain a reaction liquid B, and washing and drying to obtain modified Co3O4 nanoparticles; the mass ratio of the Co3O4 nanoparticles to the polyvinylpyrrolidone is 0.4-1.2: 1; the volume dosage of the deionized water is 50-100 mL/mg based on the mass of the Co3O4 nano particles;

(3) Dissolving zinc acetate dihydrate in deionized water, and uniformly mixing by ultrasonic waves to obtain a zinc acetate dihydrate water solution with the concentration of 0.1-0.2 mol/L; dissolving dimethyl imidazole in deionized water, and uniformly mixing by ultrasonic waves to obtain a dimethyl imidazole aqueous solution with the concentration of 0.4-0.8 mol/L; adding horseradish peroxidase and the modified Co3O4 nano particles obtained in the step (2) into the dimethyl imidazole aqueous solution, adding the zinc acetate dihydrate aqueous solution, performing ultrasonic dispersion uniformly, and reacting at 0-4 ℃ for 12-h to obtain a reaction solution C, and washing and drying to obtain an HRP/Co3O4@ ZIF-8 composite catalyst; the mass ratio of the horseradish peroxidase to the modified Co3O4 nanoparticles is 1: 1-5; the volume dosage of the zinc acetate dihydrate aqueous solution is 2-10 mL/mg based on the mass of the horseradish peroxidase; the volume dosage of the dimethyl imidazole aqueous solution is 2-10 mL/mg based on the mass of the horseradish peroxidase.

2. The HRP/Co3O4@ ZIF-8 composite catalyst of claim 1, wherein: in the step (1), the post-treatment method of the reaction solution A comprises the following steps: and centrifugally washing the obtained reaction solution A with deionized water for three times, and drying in a vacuum drying oven at 60 ℃ for 4 hours to obtain the Co3O4 nanoparticles.

3. The HRP/Co3O4@ ZIF-8 composite catalyst of claim 1, wherein: in the step (2), the post-treatment method of the reaction solution B comprises the following steps: and centrifugally washing the obtained reaction solution B with deionized water for three times, and drying in a vacuum drying oven at 60 ℃ for 4 hours to obtain the modified Co3O4 nanoparticles.

4. The HRP/Co3O4@ ZIF-8 composite catalyst of claim 1, wherein: in the step (3), the post-treatment method of the reaction solution C comprises the following steps: and centrifugally washing the obtained reaction solution C with deionized water for three times, and drying at room temperature or by freeze drying to obtain the HRP/Co3O4@ ZIF-8 composite catalyst.

5. the HRP/Co3O4@ ZIF-8 composite catalyst as defined in claim 1 is applied to catalytic conversion of O-phenylenediamine.

(I) technical field

The invention relates to a simple, efficient, mild-condition and low-cost HRP/Co3O4@ ZIF-8 composite catalyst and a preparation method thereof, belonging to the technical field of biological catalytic materials.

(II) background of the invention

The enzyme is used as an efficient biocatalyst, and is widely applied to various fields such as fine chemical production, biopharmaceuticals, renewable energy preparation, food processing and the like by virtue of the advantages of high chemical selectivity, regioselectivity, stereoselectivity and the like. However, the industrial application of enzymes is often limited by low operational stability, difficult recovery, and low reusability, and the enzyme immobilization is one of effective means for solving the above problems. Enzyme immobilization work has been developed to date, and the choice of immobilization support and method has a direct impact on the immobilization effect and may result in corresponding changes in the physical and chemical properties of the enzyme. In principle the immobilization method must keep the enzyme activity intact and not impede the diffusion of the substrate freely into and out of the enzyme active site. With the rapid development of material science, the diversity of carrier materials provides the possibility of meeting the immobilization work of enzymes with different sizes and properties. Conventional porous materials having a certain specific surface area and pore space, such as sol-gel matrix, hydrogel, organic microparticles, mesoporous silica, etc., have gained much attention as carriers for enzyme immobilization. However, there are adverse effects such as leaching, denaturation, and mass transfer limitation of the enzyme.

In contrast, due to the openness of the structure and the diversity of the material chemistry, the novel Metal Organic Frameworks (MOFs) can create stable micro-environments for different enzyme molecules through specific host/guest interactions and domain-limited effects, thereby being excellent in maintaining high enzyme loading rate and low enzyme loss rate, and even maintaining enzyme activity in extreme environments. These phenomena all indicate that MOFs can provide a very characteristic high-efficiency carrier for immobilization of different enzymes. However, since the synthesis of MOFs materials generally uses organic solvents and reacts at higher temperatures, which may have an effect on the activity of enzymes, it is necessary to synthesize the MOFs materials in advance. Although enzyme immobilization can be effectively achieved by simply attaching the enzyme to the MOFs carrier or by linking the enzyme and the MOFs carrier by peptide bonds, both of the two ways result in the enzyme on the surface of the complex being exposed to the environment without protection and easily losing activity. Therefore, if the enzyme can be fixed in the pores of the MOFs material and can be effectively prevented from being denatured in the synthesis process, the macromolecular enzyme can be effectively prevented from leaking and leaching from the fixed matrix, and the method is not influenced by environmental conditions, and has a great research significance for the application of enzyme immobilization in industry.

Disclosure of the invention

In order to overcome the defects in the prior art, the invention aims to provide an HRP/Co3O4@ ZIF-8 composite catalyst and a preparation method thereof, wherein Co3O4 nano particles are prepared and modified to improve the dispersibility, and then the nano particles and HRP are added into a precursor solution of ZIF-8 together to form the HRP/Co3O4@ ZIF-8 composite catalyst.

the technical scheme of the invention is as follows:

an HRP/Co3O4@ ZIF-8 composite catalyst is prepared by the following steps:

(1) Dissolving cobalt acetate tetrahydrate in an ethanol solvent, carrying out ultrasonic dissolution, adding 25% ammonia water by mass while carrying out vigorous stirring, fully stirring, placing in a high-pressure reaction kettle, reacting for 3-6 h at 120-150 ℃, washing and drying the obtained reaction solution to obtain Co3O4 nanoparticles; the volume dosage of the ethanol solvent is 50-60 mL/g calculated by the mass of cobalt acetate tetrahydrate; the volume usage of the ammonia water with the mass fraction of 25% is 5-15 mL/g based on the mass of the cobalt acetate tetrahydrate;

(2) dispersing the Co3O4 nanoparticles prepared in the step (1) into deionized water to obtain a dispersion liquid of Co3O4 nanoparticles, adding polyvinylpyrrolidone (PVP) into the dispersion liquid of the Co3O4 nanoparticles for ultrasonic dispersion, stirring for 6-12 h to obtain a reaction liquid B, and washing and drying to obtain modified Co3O4 nanoparticles; the mass ratio of the Co3O4 nanoparticles to the polyvinylpyrrolidone is 0.4-1.2: 1; the volume dosage of the deionized water is 50-100 mL/mg based on the mass of the Co3O4 nano particles;

(3) Dissolving zinc acetate dihydrate in deionized water, and uniformly mixing by ultrasonic waves to obtain a zinc acetate dihydrate water solution with the concentration of 0.1-0.2 mol/L; dissolving dimethyl imidazole in deionized water, and uniformly mixing by ultrasonic waves to obtain a dimethyl imidazole aqueous solution with the concentration of 0.4-0.8 mol/L; adding horseradish peroxidase (HRP) and the modified Co3O4 nano particles obtained in the step (2) into the dimethyl imidazole aqueous solution, adding the zinc acetate dihydrate aqueous solution, performing ultrasonic dispersion uniformly, and reacting at 0-4 ℃ for 12-h to obtain a reaction solution C, washing and drying to obtain an HRP/Co3O4@ ZIF-8 composite catalyst; the mass ratio of the horseradish peroxidase (HRP) to the modified Co3O4 nanoparticles is 1: 1-5; the volume dosage of the zinc acetate dihydrate aqueous solution is 2-10 mL/mg calculated by the mass of horseradish peroxidase (HRP); the volume consumption of the dimethyl imidazole aqueous solution is 2-10 mL/mg based on the mass of horseradish peroxidase (HRP).

Further, in the step (1), the post-treatment method of the reaction solution A comprises the following steps: and centrifugally washing the obtained reaction solution A with deionized water for three times, and drying in a vacuum drying oven at 60 ℃ for 4 hours to obtain the Co3O4 nanoparticles.

Further, in the step (2), the post-treatment method of the reaction solution B comprises the following steps: and centrifugally washing the obtained reaction solution B with deionized water for three times, and drying in a vacuum drying oven at 60 ℃ for 4 hours to obtain the modified Co3O4 nanoparticles.

Further, in the step (3), the post-treatment method of the reaction solution C comprises: and centrifugally washing the obtained reaction solution C with deionized water for three times, and drying at room temperature or by freeze drying (about 20 ℃) to obtain the HRP/Co3O4@ ZIF-8 composite catalyst.

the HRP/Co3O4@ ZIF-8 composite catalyst can be applied to catalytic conversion of O-phenylenediamine.

compared with the prior art, the invention has the beneficial effects that:

(1) the preparation method is simple and the operation condition is mild;

(2) HRP and Co3O4 nanoparticles are embedded in ZIF-8 together, so that the catalytic activity and stability are improved;

(3) Can effectively reduce secondary pollution and improve the reusability of the catalyst.

(IV) description of the drawings

FIG. 1 shows the results of an o-phenylenediamine catalysis experiment using the catalyst of example 1 of the present invention;

FIG. 2 shows the results of an o-phenylenediamine catalysis experiment with the catalyst of example 2 of the present invention;

FIG. 3 shows the results of an o-phenylenediamine catalysis experiment using the catalyst of example 3 of the present invention.

(V) detailed description of the preferred embodiments

The present invention will be described in detail below with reference to specific examples, but the present invention is not limited to the following examples, and various modifications and implementations are included within the technical scope of the present invention without departing from the content and scope of the present invention.

the analysis and evaluation method of each embodiment of the invention comprises the following steps:

O-phenylenediamine catalysis experiment procedure: weighing 1.0mg of HRP/Co3O4@ ZIF-8 composite catalyst, adding the HRP/Co3O4@ ZIF-8 composite catalyst into 1mL of 50mmol/L NaCl aqueous solution, performing ultrasonic dispersion uniformly, adding 1mL of toluene, and performing shaking dispersion for 30s to obtain Pickering emulsion. 1mL of 10mmol/L o-phenylenediamine substrate solution is added into the prepared Pickering emulsion and uniformly shaken. 100 μ L of 5% H2O2 solution was added and samples were taken immediately at 20s,40s,1min,2min,3min,5min,10min,15min,20min,30min intervals. 50. mu.L of each sample was added to 2.45ml of toluene (corresponding to 50-fold dilution). Then, the absorbance value is measured at the wavelength of 450nm, and the conversion rate of o-phenylenediamine is obtained.