CN109319759B - Carbon molecular sieve for purifying tetrafluoroethane and preparation method thereof - Google Patents

Abstract

The invention discloses a carbon molecular sieve for purifying tetrafluoroethane, which is characterized in that: the specific surface area is 600-700 m²(ii)/g, pore volume of 0.18 to 0.19ccIn which the internal pore diameter is

Description

Carbon molecular sieve for purifying tetrafluoroethane and preparation method thereof

Technical Field

The invention relates to a carbon molecular sieve and a preparation method thereof, in particular to a carbon molecular sieve for purifying tetrafluoroethane and a preparation method thereof.

Background

R-134a refrigerant, namely R134a, HFC134a, HFC-134a and tetrafluoroethane, wherein the tradenames are SUVA 134a, Genetron 134a, KLEA 134a and the like, the Chinese names are tetrafluoroethane, the English names are 1,1,1,2-tetrafluoroethane, the chemical names are 1,1,1,2-tetrafluoroethane and the molecular formula is CH2FCF 3. Because R-134a belongs to HFC Substances (non-ODS Substances, namely Ozone-depleting substatics), the refrigerant does not destroy the Ozone layer at all, is an environment-friendly refrigerant which is accepted and recommended by most countries in the world at present, is also a mainstream environment-friendly refrigerant at present, and is widely used for being added in the initial installation and maintenance process of new refrigeration air-conditioning equipment.

However, the tetrafluoroethane produced by many of the current processes contains some carbon dioxide impurities which can greatly affect its performance.

The Carbon Molecular sieve is a novel adsorbent developed in the seventies of the 20 th century, is an excellent nonpolar Carbon material, is used for separating air and enriching nitrogen, adopts a normal-temperature low-pressure nitrogen making process, and has the advantages of low investment cost, high nitrogen production speed, low nitrogen cost and the like compared with the traditional cryogenic high-pressure nitrogen making process. Similarly, as long as the carbon molecular sieve with proper pores can be prepared, the carbon molecular sieve can also be effectively used for adsorbing carbon dioxide in tetrafluoroethane, thereby realizing the purification of tetrafluoroethane.

Disclosure of Invention

The invention aims to provide a carbon molecular sieve for purifying tetrafluoroethane and a preparation method thereof.

The technical scheme of the invention is as follows: a carbon molecular sieve for purifying tetrafluoroethane is characterized in that: its specific surface area is 600～700m²A pore volume of 0.18 to 0.19cc/g, wherein the inner pore diameter is

The proportion of micropores in the total pore volume is 50-60%.

In the above carbon molecular sieve for tetrafluoroethane purification, further, the inner pore size is

The proportion of the micropores in the total pore volume is 11.7-11.8%, 13.5-13.6%, 27.0-27.1%, 4.1-4.2%, 13.0-13.1%, 15.1-115.2% and 11.3-11.4%, respectively.

The preparation method of the carbon molecular sieve for purifying tetrafluoroethane is characterized by comprising the following steps of:

continuously drying coconut shell carbon and phenolic resin for 4 hours at the temperature of 60-80 ℃;

secondly, stirring and mixing 50-60 parts by mass of coconut shell carbon and 40-50 parts by mass of phenolic resin to obtain a mixed material A;

thirdly, dividing the mixed material A into 1: 2: 1, respectively crushing the three parts to 10-15 nm, 16-20 nm and 22-25 nm, and then mixing the three parts together again to obtain a mixed material B;

soaking the mixed material B in 2-3% hydrochloric acid solution for 1-2 hours, and washing with water to obtain a mixed material C;

drying the mixed material C at the drying temperature of 90-100 ℃ for 0.5-1 hour;

sixthly, adding 2-6 parts by mass of gelatin powder and 2-4 parts by mass of rosin powder into the dried mixed material C, and fully stirring to obtain a mixed material D;

seventhly, processing the mixed material D into particles in a strip extrusion forming machine to obtain particles E;

eighthly, placing the particles E in a combustion furnace liner, and respectively carbonizing at 700-800 ℃, 850-900 ℃ and 950-1000 ℃ for 10 minutes, 15 minutes and 10 minutes under the protection of nitrogen to obtain a product F;

ninthly, placing the F product in a converter, cooling to 650 ℃ under the protection of nitrogen, introducing pure benzene, and cooling to room temperature at the speed of 10 ℃/min to obtain a finished product.

In the above method for preparing a carbon molecular sieve for purifying tetrafluoroethane, in the step (viii), the temperature increase process between the respective carbonization temperatures is performed at a rate of 15 ℃/min.

Compared with the prior art, the carbon molecular sieve has the pore diameter concentrated on

The ratio of the micropores is high, the adsorption rate of carbon dioxide can be improved, and tetrafluoroethane with a large molecular volume is not easy to adsorb, so that the method is extremely effective for purifying tetrafluoroethane. Moreover, the carbon molecular sieve has higher repeatability, and the performance attenuation of the carbon molecular sieve is smaller after the carbon molecular sieve is desorbed, so that the carbon molecular sieve has longer service life.

In addition, the invention also utilizes a large proportion of natural carbon source combined with phenolic resin as raw materials, a small amount of gelatin powder and rosin powder as adhesive additives, and is combined with different proportions of crushed particle size distribution and multi-stage temperature carbonization processes, so that the prepared carbon molecular sieve can be effectively controlled to have stable pore size distribution. The method has the advantages of simple process, less pollution in the preparation process, high process stability and high yield.

Detailed Description

The present invention is further illustrated by the following examples, which are not to be construed as limiting the invention.

Examples are given. The carbon molecular sieve for purifying tetrafluoroethane has a specific surface area of 600-700 m²A pore volume of 0.18 to 0.19cc/g, wherein the internal pore diameter is

The proportion of micropores in the total pore volume is 50-60%. Inner pore diameter of

The proportion of the micropores in the total pore volume is 11.7-11.8%, 13.5-13.6%, 27.0-27.1%, 4.1-4.2%, 13.0-13.1%, 15.1-115.2% and 11.3-11.4%, respectively.

A process for the preparation of a carbon molecular sieve for the purification of tetrafluoroethane comprising the steps of:

continuously drying coconut shell carbon and phenolic resin for 4 hours at the temperature of 60-80 ℃;

secondly, stirring and mixing 50-60 parts by mass of coconut shell carbon and 40-50 parts by mass of phenolic resin to obtain a mixed material A;

thirdly, dividing the mixed material A into 1: 2: 1, respectively crushing the three parts to 10-15 nm, 16-20 nm and 22-25 nm, and then mixing the three parts together again to obtain a mixed material B;

soaking the mixed material B in 2-3% hydrochloric acid solution for 1-2 hours, and washing with water to obtain a mixed material C;

drying the mixed material C at the drying temperature of 90-100 ℃ for 0.5-1 hour;

sixthly, adding 2-6 parts by mass of gelatin powder and 2-4 parts by mass of rosin powder into the dried mixed material C, and fully stirring to obtain a mixed material D;

seventhly, processing the mixed material D into particles in a strip extrusion forming machine to obtain particles E;

eighthly, placing the particles E in a combustion furnace liner, and respectively carbonizing at 700-800 ℃, 850-900 ℃ and 950-1000 ℃ for 10 minutes, 15 minutes and 10 minutes under the protection of nitrogen to obtain a product F;

ninthly, placing the F product in a converter, cooling to 650 ℃ under the protection of nitrogen, introducing pure benzene, and cooling to room temperature at the speed of 10 ℃/min to obtain a finished product.

Examples of the experiments. The carbon molecular sieve was prepared using the following steps and parameters:

continuously drying the coconut shell carbon and the phenolic resin for 4 hours at the temperature of 80 ℃;

secondly, stirring and mixing 60 kg of coconut shell carbon and 40 kg of phenolic resin to obtain a mixed material A;

thirdly, dividing the mixed material A into 1: 2: 1, respectively crushing the three parts to 10-15 nm, 16-20 nm and 22-25 nm, and then mixing the three parts together again to obtain a mixed material B;

soaking the mixed material B in 2-3% hydrochloric acid solution for 1.5 hours, and washing with water to obtain a mixed material C;

fifthly, drying the mixed material C at 85 ℃ for 0.8 hour;

sixthly, adding 4 kg of gelatin powder and 3 kg of rosin powder into the dried mixed material C, and fully stirring to obtain a mixed material D;

seventhly, processing the mixed material D into particles in a strip extrusion forming machine to obtain particles E;

eighthly, placing the particles E in a combustion furnace liner, and respectively carbonizing at 700 ℃, 850 ℃ and 950 ℃ for 10 minutes, 15 minutes and 10 minutes under the protection of nitrogen to obtain a product F;

ninthly, placing the F product in a converter, cooling to 650 ℃ under the protection of nitrogen, introducing pure benzene, and cooling to room temperature at the speed of 10 ℃/min to obtain a finished product.

According to analysis statistics, the pore size distribution of the finished product is as follows:

and (5) performing repeated experiments.

The experimental conditions are as follows: roasting at 180 ℃ for 4 hours under vacuum condition, wherein the temperature is as follows: -20 ℃, pressure: 0.6MPa, tetrafluoroethane mass: 180g, CO₂The content is as follows: 116 PPM.

The experimental results are as follows: the total relative adsorption breakthrough of the carbon molecular sieve is 29.23mg, and the relative adsorption quantity is 0.162 mg/g. The carbon molecular sieve can convert CO₂The content is absorbed to be below 4.5PPM,and can be maintained for about 480 min. The adsorption and desorption are repeated for 9 times, and the same carbon molecular sieve can be used for separating CO₂The adsorption of the content below 5PPM can be maintained for about 480min, and the repeatability is good.

Claims (3)

1. A carbon molecular sieve for tetrafluoroethane purification, characterized in that: the specific surface area is 600-700 m²The specific pore volume is 0.18-0.19 cc/g, wherein the internal pore diameter is 3.2-4A, 4-5A, 5-6.3A, 6.3-8A, 8-10A, 10-12.6A, and the ratio of micropores of 12.6-15.9A to the total pore volume is 11.7-11.8%, 13.5-13.6%, 27.0-27.1%, 4.1-4.2%, 13.0-13.1%, 15.1-115.2% and 11.3-11.4%, respectively.

2. The process for the preparation of a carbon molecular sieve for tetrafluoroethane purification according to claim 1, comprising the steps of:

continuously drying coconut shell carbon and phenolic resin for 4 hours at the temperature of 60-80 ℃;

secondly, stirring and mixing 50-60 parts by mass of coconut shell carbon and 40-50 parts by mass of phenolic resin to obtain a mixed material A;

thirdly, dividing the mixed material A into 1: 2: 1, respectively crushing the three parts to 10-15 nm, 16-20 nm and 22-25 nm, and then mixing the three parts together again to obtain a mixed material B;

soaking the mixed material B in 2-3% hydrochloric acid solution for 1-2 hours, and washing with water to obtain a mixed material C;

drying the mixed material C at the drying temperature of 90-100 ℃ for 0.5-1 hour;

sixthly, adding 2-6 parts by mass of gelatin powder and 2-4 parts by mass of rosin powder into the dried mixed material C, and fully stirring to obtain a mixed material D;

seventhly, processing the mixed material D into particles in a strip extrusion forming machine to obtain particles E;

eighthly, placing the particles E in a combustion furnace liner, and respectively carbonizing at 700-800 ℃, 850-900 ℃ and 950-1000 ℃ for 10 minutes, 15 minutes and 10 minutes under the protection of nitrogen to obtain a product F;

ninthly, placing the F product in a converter, cooling to 650 ℃ under the protection of nitrogen, introducing pure benzene, and cooling to room temperature at the speed of 10 ℃/min to obtain a finished product.

3. The method of claim 2 for the preparation of a carbon molecular sieve for tetrafluoroethane purification, characterized in that: in the step (viii), the temperature rise process between the respective carbonization temperatures is performed at a rate of 15 ℃/min.