CN111747413B

CN111747413B - Preparation method of pellet molybdenum carbide easy to separate and recycle

Info

Publication number: CN111747413B
Application number: CN201910247575.6A
Authority: CN
Inventors: 林少华; 范舒婷; 刘国华; 陈阳; 肖冬梅; 陈忱
Original assignee: Nanjing Forestry University
Current assignee: Nanjing Forestry University
Priority date: 2019-03-27
Filing date: 2019-03-27
Publication date: 2023-05-30
Anticipated expiration: 2039-03-27
Also published as: CN111747413A

Abstract

The preparation method of the pellet molybdenum carbide easy to separate and recycle comprises the steps of firstly mixing inorganic mineral clay powder and molybdenum carbide powder according to the mass ratio of (0.5-3) to 1, and then mixing the mixture with sodium alginate, polyethylene glycol and methylcellulose according to the mass ratio of: fully mixing the materials according to the ratio of 20:0.5-3.5:0.05-0.15:0.05-1.5:12-20 to form a plastic mixed material; then making into pill and oven drying; roasting for 0.5-2h at 500-800 ℃ under the protection of nitrogen or helium; and finally naturally cooling to room temperature to obtain the pellet molybdenum carbide which is easy to separate and recycle. The pellet molybdenum carbide prepared by the method maintains the catalytic activity of the molybdenum carbide and has the advantages of simple preparation process, mild condition, high mechanical strength of particles, controllable particle size and the like.

Description

Preparation method of pellet molybdenum carbide easy to separate and recycle

Technical Field

The invention relates to a preparation method of pellet molybdenum carbide which is easy to separate and recycle, simple in manufacturing process and high in catalytic activity, and belongs to the technical field of energy and catalytic materials.

Background

In recent years, carbide has attracted considerable attention from researchers as a catalytic material. Molybdenum carbide is a "mesenchymal alloy" formed by embedding smaller-radius C atoms into a larger-radius metallic Mo atom lattice, thereby forming a simple lattice structure. The metal Mo atom transfers electrons to the C atom, and can form three chemical bonds of a metal bond, an ionic bond and a covalent bond, thereby resulting in excellent properties of the metal Mo, which are different from those of the parent metal, after being carbonized. The molybdenum carbide has noble metal-like catalytic properties, has good catalytic properties in hydrogenation reaction, hydrogen production reaction, oxygen reduction reaction, desulfurization reaction, denitrification reaction and other aspects, and also has excellent properties such as high melting point, high stability, roasting resistance and the like, so that the molybdenum carbide has great attention in various high-temperature, abrasion and chemical corrosion resistant mechanical and environmental protection fields. Molybdenum carbide has a strong price advantage over the platinum group noble metals and has good poisoning resistance, and has been favored by researchers in recent years.

The preparation method of the molybdenum carbide mainly comprises the following steps: a temperature programmed reaction method, a thermal decomposition method, a liquid phase reaction method, a chemical vapor deposition method, an organic-inorganic hybridization method, an ultrasonic method, a microwave preparation method and the like. Or modifying molybdenum carbide, such as doping of hetero atoms and adding metal auxiliary agents. The prepared molybdenum carbide is mainly nano-sized particles, and has the problems of large specific surface area, high catalytic efficiency, easy loss, difficult separation and recovery and the like when being applied to some fields, such as environmental protection fields.

Disclosure of Invention

Technical problems: the invention aims to disclose a preparation method of pellet molybdenum carbide which is easy to separate and recycle. The pellet molybdenum carbide prepared by the method maintains the catalytic activity of the molybdenum carbide and has the advantages of simple preparation process, mild condition, high mechanical strength of particles, controllable particle size and the like.

The technical scheme is as follows: the preparation method of the pellet molybdenum carbide easy to separate and recycle comprises the following steps:

firstly, fully mixing inorganic mineral clay powder and molybdenum carbide powder, and then fully mixing the mixture with sodium alginate, polyethylene glycol and methylcellulose; adding deionized water and fully stirring to form a plastic mixed material; then pelleting and granulating the obtained plastic mixture; drying the pellet particles; finally roasting and naturally cooling under the protection of inert gas, thereby obtaining the pellet molybdenum carbide which is easy to separate and recycle.

When the materials are mixed, the mass ratio of the inorganic mineral clay powder to the molybdenum carbide powder is (0.5-3) to 1.

When materials are mixed, the mass ratio of the mixture of inorganic mineral clay powder and molybdenum carbide powder, sodium alginate, polyethylene glycol, methylcellulose and deionized water is as follows: 20:0.5-3.5:0.05-0.15:0.05-1.5:12-20.

The inorganic mineral clay is one or more of montmorillonite, palygorskite and bentonite, and is sieved by a 200-mesh sieve.

The molybdenum carbide powder is nano or micron scale.

The drying temperature of the pellet particles is 60-80 ℃ and the drying time is 12-24 hours.

The inert gas is nitrogen or helium, and the airflow velocity is 100-250 mL/min.

The roasting temperature is 500-800 ℃, the temperature raising program is 2-10 ℃/min, and the roasting time is kept for 0.5-2h at 500-800 ℃.

The beneficial effects are that: the invention has the following advantages:

1. the pellet molybdenum carbide prepared by the invention is easy to separate, and the difficult problems that the molybdenum carbide is easy to run off and difficult to separate and recycle when being applied in some fields are overcome.

2. The pellet heat treatment process has low roasting temperature, low power consumption and simplified technological process.

3. The pellet molybdenum carbide prepared by the invention has high mechanical strength and controllable particle size.

4. The invention has the advantages of easily available raw materials, simple process and equipment, convenient operation and easy mass production.

Drawings

FIG. 1 is a process flow diagram of the present invention

FIG. 2 is an X-ray diffraction analysis of a sample of example 1 of the present invention

FIG. 3 is an X-ray diffraction analysis of a sample of example 2 of the present invention

FIG. 4 is an X-ray diffraction analysis of a sample of example 3 of the present invention

Detailed Description

In order to achieve the purpose, the invention adopts inorganic mineral clay, organic sodium alginate, polyethylene glycol and methylcellulose as adhesives, and organic materials also serve as pore-forming agents. Mixing the powder with molybdenum carbide powder according to a certain proportion, processing the mixture into pellet particles with the required particle size, and roasting the pellet particles under the protection of inert gas to prepare the pellet molybdenum carbide which is easy to separate and recycle. The method specifically comprises the following steps:

first step, mixing materials

Fully mixing inorganic mineral clay powder ground by a 200-mesh sieve and molybdenum carbide powder, and fully mixing the mixture with sodium alginate, polyethylene glycol and methylcellulose; adding deionized water and fully stirring to form a plastic mixed material;

when the materials are mixed, the mass ratio of the inorganic mineral clay powder to the molybdenum carbide powder is (0.5-3) to 1. The mass ratio of the mixture of inorganic mineral clay powder and molybdenum carbide powder, sodium alginate, polyethylene glycol, methylcellulose and deionized water is as follows: 20:0.5-3.5:0.05-0.15:0.05-1.5:12-20.

Second step, making pill

Granulating the obtained plastic mixture by a granulator, wherein the particle size can be adjusted according to the requirement.

Third step, drying

And then the obtained pellet particles are dried in an electrothermal blowing drying oven at 60-80 ℃ for 12-24 hours.

Fourth step, roasting

Under the protection of nitrogen or helium, the temperature is raised to 500-800 ℃ in a muffle furnace at the speed of 2-10 ℃/min, and the temperature is kept for 0.5-2h. The flow rate of the nitrogen or helium gas is 100-250 mL/min.

Fifth step, naturally cooling

Finally, the pellet molybdenum carbide which is easy to separate and recycle is prepared.

The inorganic mineral clay used in the invention is one or a mixture of more of montmorillonite, palygorskite and bentonite. Drying one or more of montmorillonite, palygorskite and bentonite at 105deg.C, grinding into powder, sieving with 200 mesh sieve, and sealing.

The molybdenum carbide is powder prepared by a high-temperature carbothermal reduction method, a program heating pyrolysis method, a chemical vapor deposition method, a liquid phase reaction method and the like.

Example 1:

mixing materials: fully mixing montmorillonite powder and molybdenum carbide powder in a mass ratio of 3:1, and fully mixing and stirring the mixture with sodium alginate, polyethylene glycol, methylcellulose and deionized water in a mass ratio of 20:3:0.09:1:18 to form a plastic material.

Preparing pills: the obtained plastic mixture was granulated by a granulator, and the obtained particle size was 1mm.

And (3) drying: and drying the obtained pellet particles in an electrothermal blowing drying oven at 80 ℃ for 12 hours.

Roasting: under nitrogen protection, the temperature was raised to 750℃in a muffle furnace at a rate of 2℃per minute and maintained for 2 hours. The flow rate of the nitrogen gas stream was 100mL/min.

Finally naturally cooling to room temperature to obtain the pellet molybdenum carbide which is easy to separate and recycle.

Fig. 2 is an X-ray diffraction (XRD) analysis of the sample, and shows that diffraction peaks at 34.5 °, 37.4 °, 39.5 °, 52.1 °, 61.8 °, 69.5 ° are characteristic peaks of molybdenum carbide, which indicates that the prepared pellets retain high-activity molybdenum carbide crystals.

Example 2:

mixing materials: mixing palygorskite powder and molybdenum carbide powder in the mass ratio of 2 to 1, and mixing the mixture with sodium alginate, polyethylene glycol, methyl cellulose and deionized water in the mass ratio of 20 to 2 to 0.1 to 1 to 13 to form plastic material.

Preparing pills: the obtained plastic mixture was granulated by a granulator, and the obtained particle size was 3mm.

And (3) drying: and then drying the obtained pellet particles in an electrothermal blowing drying oven at 60 ℃ for 24 hours.

Roasting: under nitrogen protection, the temperature was raised to 600℃in a muffle furnace at a rate of 5℃per minute and maintained for 2 hours. The flow rate of the nitrogen gas stream was 100mL/min.

Fig. 3 shows sample X-ray diffraction (XRD) analysis, and shows that diffraction peaks at 34.5 °, 37.4 °, 39.5 °, 52.1 °, 61.8 °, 69.5 ° are characteristic peaks of molybdenum carbide, which indicates that the prepared pellets retain high-activity molybdenum carbide crystals.

Example 3:

mixing materials: fully mixing bentonite powder and molybdenum carbide powder according to the mass ratio of 1:1, and fully mixing and stirring the mixture, sodium alginate, polyethylene glycol, methylcellulose and deionized water according to the mass ratio of 20:2.5:0.1:1.5:15 to form a plastic material.

Roasting: under nitrogen protection, the temperature was raised to 500℃in a muffle furnace at a rate of 5℃per minute and maintained for 2 hours. The nitrogen flow rate was 150mL/min.

Fig. 4 is an X-ray diffraction (XRD) analysis of the sample, and shows that diffraction peaks at 34.5 °, 37.4 °, 39.5 °, 52.1 °, 61.8 °, 69.5 ° are characteristic peaks of molybdenum carbide, which indicates that the prepared pellets retain high-activity molybdenum carbide crystals.

Claims

1. A preparation method of pellet molybdenum carbide easy to separate and recycle is characterized by comprising the following steps: the preparation method specifically comprises the following steps:

first step, mixing materials

Firstly, fully mixing inorganic mineral clay powder and molybdenum carbide powder, and then fully mixing the mixture with sodium alginate, polyethylene glycol and methylcellulose; adding deionized water and fully stirring to form a plastic mixed material;

when materials are mixed, the mass ratio of the inorganic mineral clay powder to the molybdenum carbide powder is (0.5-3) to 1, and the mass ratio of the mixture of the inorganic mineral clay powder and the molybdenum carbide powder, sodium alginate, polyethylene glycol, methylcellulose and deionized water is as follows: 20:0.5-3.5:0.05-0.15:0.05-1.5:12-20;

second step, making pill

Granulating the obtained plastic mixture by a pelleting machine, wherein the particle size can be adjusted according to the requirement;

third step, drying

Drying the obtained pellet particles in an electrothermal blowing drying oven at 60-80 ℃ for 12-24 hours;

fourth step, roasting

Under the protection of nitrogen or helium, heating to 500-800 ℃ at a speed of 2-10 ℃/min in a muffle furnace, and keeping the flow speed of the nitrogen or helium at 100-250 mL/min for 0.5-2h;

fifth step, naturally cooling

And under the protection of nitrogen or helium, continuously and naturally cooling to room temperature to obtain the pellet molybdenum carbide which is easy to separate and recycle.

2. The method for preparing the pellet molybdenum carbide easy to separate and recycle according to claim 1, which is characterized in that: the inorganic mineral clay powder is one or more of montmorillonite, palygorskite and bentonite, and is prepared by drying at 105 ℃, grinding into powder, sieving with 200 mesh sieve, and sealing.

3. The method for preparing the pellet molybdenum carbide easy to separate and recycle according to claim 1, which is characterized in that: the molybdenum carbide is powder prepared by a high-temperature carbothermal reduction method, a program heating pyrolysis method, a chemical vapor deposition method or a liquid phase reaction method.