Coal tar mixing-pyrolysis recovery method taking magnesium oxide as catalyst and template agent

Abstract

The invention provides a coal tar mixing-pyrolysis recovery method taking magnesium oxide as a catalyst and a template agent, which comprises the following steps: carrying out ultrasonic dispersion treatment on magnesium oxide in water, then adding coal tar and dichloromethane, and stirring at normal temperature to obtain a mixed system; stirring at 80 DEG C, evaporating out the solvent to obtain a carbon-containing precursor, grinding, and carrying out thermal cracking to obtain a coarse carbon material after thermal cracking; pyrolysis steam enters an absorption bottle and is collected as pyrolysis oil; uncondensed gas is collected into the gas collecting bag; and carrying out acid pickling, water washing, ethanol washing and drying on the crude carbon material after thermal cracking to obtain the refined mesoporous carbon material. According to the method, the magnesium oxide is used as a catalyst and a template agent for pyrolysis for pyrolysis treatment, and the mixing process of the magnesium oxide and the coal tar is improved, so that efficient resource recycling of the coal tar is realized, the coal tar can be completely eaten, and products are high-surface-area mesoporous carbon and low-molecular-weight aromatic hydrocarbon compounds; and great economic benefits can be brought.

Description

Technical Field

[0001] The invention belongs to the technical field of coal tar processing, and in particular relates to a coal tar mixing-pyrolysis recovery method using magnesium oxide as a catalyst and a template. Background Art

[0002] At present, the main methods for treating coal tar are coal tar hydrocracking process and coal tar pyrolysis process. The coal tar hydrogenation process mainly includes: pretreatment (dehydration and desalination treatment to prevent catalyst poisoning), hydrogenation reaction (reacting with hydrogen under the action of catalyst to convert into low molecular weight hydrocarbon compounds), and product separation (separating products with different boiling points by distillation and condensation). However, this method still has a series of problems, such as catalyst life, high energy consumption, and treatment of wastewater and waste gas, which seriously affect subsequent applications. Pyrolysis, as a simple and promising chemical method, is to pyrolyze and carbonize coal tar under high temperature and inert atmosphere, which can not only collect low molecular weight aromatic compounds, but also obtain carbon materials, which have certain economic value and environmental significance. However, direct pyrolysis of coal tar can only obtain carbon materials such as carbon black with very low specific surface area, and the economic value is not high. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a coal tar mixing-pyrolysis recovery method using magnesium oxide as a catalyst and a template for the above-mentioned deficiencies in the prior art. The method uses magnesium oxide as a pyrolysis catalyst and a template for pyrolysis treatment of coal tar, and improves the mixing process of magnesium oxide and coal tar, thereby realizing efficient resource recovery and utilization of coal tar, which can basically achieve complete recovery. The products are high surface area mesoporous carbon and low molecular weight aromatic compounds, which can bring greater economic benefits.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a coal tar mixing-pyrolysis recovery method using magnesium oxide as a catalyst and a template, the method comprising:

[0005] S1, subjecting magnesium oxide to ultrasonic dispersion treatment in water, then adding coal tar and dichloromethane, and stirring at room temperature to obtain a mixed system;

[0006] S2, stirring the mixed system obtained in S1 at a temperature of 80° C., distilling off the solvent, and obtaining a carbon-containing precursor;

[0007] S3, grinding the carbon-containing precursor obtained in S2, and then performing thermal cracking to obtain a crude carbon material after thermal cracking; in the thermal cracking stage, the pyrolysis steam enters an absorption bottle and is collected as pyrolysis oil; the uncondensed gas is collected in a gas collection bag;

[0008] The thermal cracking reaction procedure was as follows: under nitrogen atmosphere, the temperature was raised from room temperature to 650 °C at a heating rate of 10 °C / min and kept at a constant temperature for 3 h;

[0009] S4. The crude carbon material obtained after thermal cracking in S3 is sequentially acid-washed, water-washed, ethanol-washed, and dried to obtain a refined mesoporous carbon material.

[0010] Preferably, the mass ratio of magnesium oxide, water, coal tar and dichloromethane in S1 is 1:4:1:4.

[0011] Preferably, the absorption bottle in S3 contains ethylene glycol.

[0012] Preferably, the acid washing method in S4 is: adding the crude carbon material after thermal cracking, magnetic particles and 1M hydrochloric acid into a round-bottom flask equipped with a condenser reflux tube, stirring and reacting at a temperature of 90° C. for 1 hour to obtain an acid-treated carbon material.

[0013] Preferably, the drying temperature in S4 is 110° C., and the drying time is 12 h.

[0014] Preferably, the specific surface area of ​​the refined mesoporous carbon material in S4 is 1600 m 2 / g.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] The invention provides a new resource recovery method for coal tar, wherein magnesium oxide is used as a catalyst and template for pyrolysis of coal tar, a solvent is added to dissolve the coal tar, and then magnesium oxide is added thereto and highly dispersed, and then the solvent is evaporated to form a uniformly mixed solid mixture, thereby achieving uniform mixing of magnesium oxide and coal tar, and the solid mixture is subjected to pyrolysis and carbonization treatment to obtain a carbon material with uniform magnesium oxide distribution, and then the magnesium oxide is removed by an acid solution to obtain a mesoporous carbon material with uniform pores and a high specific surface area. The invention can significantly increase the specific surface area of ​​the final synthetic carbon material and reduce the carbonization temperature.

[0017] The present invention is further described in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0018] Example 1

[0019] The coal tar mixing-pyrolysis recovery method using magnesium oxide as a catalyst and template in this embodiment is as follows:

[0020] S1, 5 g of magnesium oxide was subjected to ultrasonic dispersion treatment in 20 g of water, and then 5 g of coal tar and 20 g of dichloromethane were added, and stirred at room temperature to obtain a mixed system;

[0021] S2, stirring the mixed system obtained in S1 at a temperature of 80° C., distilling off the solvent, and obtaining a carbon-containing precursor;

[0022] The specific surface area of ​​the carbon material obtained by simply mixing magnesium oxide as a catalyst and template for pyrolysis with coal tar and then pyrolyzing it is much larger than that of the carbon material obtained by direct pyrolysis without adding magnesium oxide (20m 2 / g or less) has significantly improved (100-200m 2 / g or so), but it is still unsatisfactory. The reason may be that coal tar is still relatively dilute, and direct mixing with magnesium oxide will result in serious uneven mixing problems, resulting in a certain proportion of carbon materials after pyrolysis not forming a whole with magnesium oxide and still being similar to carbonization alone when there is no template, so the final specific surface area is relatively low. Therefore, this embodiment continues to innovate the mixing process of coal tar and magnesium oxide, by adding a solvent (water, dichloromethane) to dissolve the coal tar, and then adding magnesium oxide thereto to highly disperse, and then evaporating the solvent to form a uniformly mixed solid mixture, thereby achieving a uniform mixing of magnesium oxide and coal tar. The solid mixture is subjected to pyrolysis and carbonization treatment to obtain a carbon material with uniform distribution of magnesium oxide, and then the magnesium oxide is removed by an acid solution to obtain a mesoporous carbon material with uniform pores and a high specific surface area;

[0023] S3, grinding the carbon-containing precursor obtained in S2, and then performing thermal cracking to obtain a crude carbon material after thermal cracking (6.7 g); in the thermal cracking stage, the pyrolysis vapor enters an absorption bottle (ethylene glycol, 150 g) and is collected as pyrolysis oil; the uncondensed gas is collected in a gas collection bag;

[0024] The main components of pyrolysis oil are: toluene, xylene, ethylbenzene, etc.

[0025] The main components of the uncondensed gas are C1-C4 alkanes, etc.

[0026] The thermal cracking reaction procedure was as follows: under nitrogen atmosphere, the temperature was raised from room temperature to 650 °C at a heating rate of 10 °C / min and kept at a constant temperature for 3 h;

[0027] Conventional coal tar carbonization temperature mostly needs to be higher than 1000°C, and the optimized temperature of the present invention is 650°C, which indicates that the alkalinity of magnesium oxide has a catalytic effect that is beneficial to the condensation carbonization reaction during the heat treatment of coal tar;

[0028] S4, the crude carbon material after thermal cracking obtained in S3 was acid washed, water washed, ethanol washed, and dried at a temperature of 110°C for 12 hours to obtain a carbon material with a specific surface area of ​​1600m 2 / g of refined mesoporous carbon material (1.6g);

[0029] The acid washing method is as follows: adding the crude carbon material after thermal cracking, a magnet and 150 mL of 1M hydrochloric acid into a round-bottom flask equipped with a condenser reflux tube, stirring and reacting at a temperature of 90° C. for 1 hour to obtain an acid-treated carbon material.

[0030] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A coal tar mixing-pyrolysis recovery method using magnesium oxide as a catalyst and a template, characterized in that: The method is: S1, subjecting magnesium oxide to ultrasonic dispersion treatment in water, then adding coal tar and dichloromethane, and stirring at room temperature to obtain a mixed system; S2, stirring the mixed system obtained in S1 at a temperature of 80° C., distilling off the solvent, and obtaining a carbon-containing precursor; S3, grinding the carbon-containing precursor obtained in S2, and then performing thermal cracking to obtain a crude carbon material after thermal cracking; in the thermal cracking stage, the pyrolysis steam enters an absorption bottle and is collected as pyrolysis oil; the uncondensed gas is collected in a gas collection bag; The thermal cracking reaction procedure was as follows: under nitrogen atmosphere, the temperature was raised from room temperature to 650 °C at a heating rate of 10 °C / min and kept at a constant temperature for 3 h; S4. The crude carbon material obtained after thermal cracking in S3 is sequentially acid-washed, water-washed, ethanol-washed, and dried to obtain a refined mesoporous carbon material.

2. The method for recovering coal tar by mixing and pyrolysis using magnesium oxide as a catalyst and a template according to claim 1, characterized in that: The mass ratio of magnesium oxide, water, coal tar and dichloromethane in S1 is 1:4:1:

4.

3. The method for recovering coal tar by mixing and pyrolysis using magnesium oxide as a catalyst and a template according to claim 1, characterized in that: The absorption bottle in S3 contains ethylene glycol.

4. The method for recovering coal tar by mixing and pyrolysis using magnesium oxide as a catalyst and a template according to claim 1, characterized in that: The acid washing method in S4 is: adding the crude carbon material after thermal cracking, magnetic particles and 1M hydrochloric acid into a round-bottom flask equipped with a condenser reflux tube, stirring and reacting at a temperature of 90° C. for 1 hour to obtain an acid-treated carbon material.

5. The method for recovering coal tar by mixing and pyrolysis using magnesium oxide as a catalyst and a template according to claim 1, characterized in that: The drying temperature in S4 is 110° C. and the drying time is 12 h.

6. The method for recovering coal tar by mixing and pyrolysis using magnesium oxide as a catalyst and a template according to claim 1, characterized in that: The specific surface area of ​​the refined mesoporous carbon material described in S4 is 1600 m 2 / g.