TDI (toluene diisocynate) residue dissolution-pyrolysis recovery method taking magnesium oxide as catalyst and template agent

Abstract

The invention provides a TDI (toluene diisocynate) residue dissolution-pyrolysis recovery method taking magnesium oxide as a catalyst and a template agent, which comprises the following steps: grinding and crushing TDI residues, adding ethylene glycol into the crushed TDI residues, heating to 180 DEG C, keeping reflux for 1 hour, adding magnesium oxide, continuously keeping reflux for 1.5 hours at the temperature of 180 DEG C, and after the temperature of a reaction system is reduced to room temperature, cooling to room temperature to obtain a TDI residue solution; filtering, washing a filter cake with deionized water, and drying to obtain a carbon-containing precursor; after grinding, performing thermal cracking to obtain a coarse carbon material after thermal cracking; in the thermal cracking stage, pyrolysis steam enters an absorption bottle and is collected as pyrolysis oil; uncondensed gas is collected into the gas collecting bag; and sequentially 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 disclosed by the invention, the TDI residues are subjected to pyrolysis treatment by singly taking magnesium oxide as a catalyst and a template agent for pyrolysis, so that efficient resource recycling of the TDI residues is realized, and the aim of completely eating the TDI residues can be basically achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of TDI residue treatment, and in particular relates to a TDI residue dissolution-pyrolysis recovery method using magnesium oxide as a catalyst and a template. Background Art

[0002] TDI is the abbreviation of toluene diisocyanate. TDI is an important basic chemical material for the manufacture of polyurethane. Due to the large production and investment of TDI and its high technological level, it is also recognized as a "two major and one high" product internationally. Its products are widely used in home, construction, automobiles, and coatings. Polyurethane is one of the six most promising synthetic materials in the world. It has the functions of wear resistance, low temperature resistance, oil resistance, and ozone resistance. In recent years, it has achieved rapid development in my country. Toluene diisocyanate (TDI), as one of the main raw materials of the polyurethane industry, has become one of the most widely used varieties of isocyanate compounds due to its excellent performance and wide range of uses.

[0003] The heavy solvent process produces 5% (by mass of TDI) of tar residue. Currently, there are two ways to treat this residue, namely landfill and incineration. Both methods do not meet the requirements of today's green environmental protection, because landfill requires the occupation of land, and incineration produces a large amount of CO2 and nitrogen oxides, increasing environmental pollution. Therefore, the development of energy-saving and environmentally friendly residue treatment methods is of great significance to the clean production of the TDI industry.

[0004] At present, the hydrolysis method for treating the tar waste generated in the TDI preparation process is a well-known technology in the art. For example, the hydrolysis is carried out at a temperature of 350°C or lower, in a gas-liquid state or a liquid state, and an aqueous ammonia solution, an aqueous solution containing an alkali such as an alkaline earth metal hydroxide, or an aqueous solution containing an acid such as an inorganic or organic acid is added. Superheated steam of 200-400°C can also be used for hydrolysis at a pressure as low as 1-5 atmospheres. For tar, it shows fluidity at a temperature of 100°C or lower due to its high content of low-boiling components such as toluene diisocyanate, so it can be decomposed to a limited extent with supercritical water or subcritical water. The hydrolysis method can only treat a part of the residue (about 60%), and the remaining residue that cannot be hydrolyzed (about 40%) is still simply discarded without an ideal treatment method, resulting in waste of resources and environmental pollution. In addition, the hydrolysis products of the hydrolysis method in previous studies cannot be completely separated and fully utilized, making research and industrial application difficult. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a TDI residue dissolution-pyrolysis recovery method using magnesium oxide as a catalyst and template in view of the deficiencies of the above-mentioned prior art. The method uses magnesium oxide alone as a pyrolysis catalyst and template to pyrolyze TDI residue, thereby realizing efficient resource recovery and utilization of TDI residue, which can basically achieve complete recovery.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a TDI residue dissolution-pyrolysis recovery method using magnesium oxide as a catalyst and template, the method is:

[0007] S1, grinding and crushing TDI residue to obtain crushed TDI residue;

[0008] S2, adding ethylene glycol to the crushed TDI residue obtained in S1, heating to 180°C, maintaining reflux for 1 hour, adding magnesium oxide, and continuing to maintain reflux at 180°C for 1.5 hours. After the temperature of the reaction system drops to room temperature, filtering, washing the filter cake with deionized water, and drying, to obtain a carbon-containing precursor;

[0009] 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;

[0010] The thermal cracking reaction procedure was as follows: in a nitrogen atmosphere, the temperature was raised from room temperature to 500°C to 650°C at a heating rate of 10°C / min and the temperature was maintained for 4 h;

[0011] 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.

[0012] Preferably, the mass ratio of the crushed TDI residue, ethylene glycol and magnesium oxide in S2 is 1:(2-10):1.

[0013] Preferably, the absorption bottle in S3 contains ethylene glycol.

[0014] 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.

[0015] Preferably, the drying temperature in S4 is 110° C., and the drying time is 12 h.

[0016] Preferably, the specific surface area of ​​the refined mesoporous carbon material in S4 is 1300 m 2 / g~1600m 2 / g.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. The present invention uses magnesium oxide as a single catalyst and template for pyrolysis to pyrolyze TDI residue, thereby realizing efficient resource recovery and utilization of TDI residue, which can basically achieve complete utilization. The products are nitrogen-containing mesoporous carbon with high specific area and benzene organic substances such as toluene and meta-xylene, which can bring greater economic benefits.

[0019] 2. The present invention adopts the method of ethylene glycol dissolution-mixing-filtration-direct pyrolysis. The whole process is completely an organic system without alkali or salt. The product is very easy to separate by distillation and very easy to perform chromatographic analysis, thereby solving the problem of product separation and analysis. At the same time, the yield of mesoporous carbon material obtained by this process can reach 33% to 35% (based on TDI residue).

[0020] The present invention is further described in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0021] Example 1

[0022] The TDI residue dissolution-pyrolysis recovery method using magnesium oxide as a catalyst and template in this embodiment is as follows:

[0023] S1, grinding and crushing TDI residue to obtain crushed TDI residue;

[0024] S2, add 10g of ethylene glycol to 5g of the crushed TDI residue obtained in S1, heat to 180°C, keep reflux for 1h, add 5g of magnesium oxide, continue to keep reflux at 180°C for 1.5h, after the temperature of the reaction system drops to room temperature, filter, wash the filter cake with deionized water, and dry to obtain a carbon-containing precursor, which is a uniform mixture of TDI residue and magnesium oxide;

[0025] S3, grinding the carbon-containing precursor obtained in S2, and then performing thermal cracking to obtain a crude carbon material after thermal cracking (6.8 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;

[0026] The main components of pyrolysis oil are: toluene, m-xylene, 4-ethyltoluene, etc.

[0027] The main components of the uncondensed gas are small molecular hydrocarbons, etc.

[0028] 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 4 h;

[0029] S4, the crude carbon material after thermal cracking obtained in S3 was acid washed, water washed, ethanol washed, and dried at 110°C for 12h to obtain a specific surface area of ​​1600m 2 / g of refined mesoporous carbon material (1.75g); the acid washing method is: adding the crude carbon material after thermal cracking, magnetron and 1M hydrochloric acid into a round-bottom flask equipped with a condenser reflux tube, stirring the reaction at a temperature of 90°C for 1h to obtain the acid-treated carbon material.

[0030] Example 2

[0031] The TDI residue dissolution-pyrolysis recovery method using magnesium oxide as a catalyst and template in this embodiment is as follows:

[0032] S1, grinding and crushing TDI residue to obtain crushed TDI residue;

[0033] S2, add 50g of ethylene glycol to 5g of the crushed TDI residue obtained in S1, heat to 180°C, keep reflux for 1h, add 5g of magnesium oxide, continue to keep reflux at 180°C for 1.5h, after the temperature of the reaction system drops to room temperature, filter, wash the filter cake with deionized water, and dry to obtain a carbon-containing precursor, that is, a uniform mixture of TDI residue and magnesium oxide;

[0034] 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;

[0035] The main components of pyrolysis oil are: toluene, m-xylene, 4-ethyltoluene, etc.

[0036] The main components of the uncondensed gas are small molecular hydrocarbons, etc.

[0037] The thermal cracking reaction procedure was as follows: under nitrogen atmosphere, the temperature was raised from room temperature to 500 °C at a heating rate of 10 °C / min and kept at a constant temperature for 4 h;

[0038] S4, the crude carbon material after thermal cracking obtained in S3 was acid washed, water washed, ethanol washed, and dried at 110°C for 12h to obtain a specific surface area of ​​1500m 2 / g of refined mesoporous carbon material (1.65g); the acid washing method is: adding the crude carbon material after thermal cracking, magnetron and 1M hydrochloric acid into a round-bottom flask equipped with a condenser reflux tube, stirring the reaction at a temperature of 90°C for 1h to obtain the acid-treated carbon material.

[0039] 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 TDI residue dissolution-pyrolysis recovery method using magnesium oxide as a catalyst and template, characterized in that: The method is: S1, grinding and crushing TDI residue to obtain crushed TDI residue; S2, adding ethylene glycol to the crushed TDI residue obtained in S1, heating to 180°C, maintaining reflux for 1 hour, adding magnesium oxide, and continuing to maintain reflux at 180°C for 1.5 hours. After the temperature of the reaction system drops to room temperature, filtering, washing the filter cake with deionized water, and drying, to obtain 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: in a nitrogen atmosphere, the temperature was raised from room temperature to 500°C to 650°C at a heating rate of 10°C / min and the temperature was maintained for 4 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 TDI residue dissolution-pyrolysis recovery method using magnesium oxide as a catalyst and template according to claim 1, characterized in that: The mass ratio of the crushed TDI residue, ethylene glycol and magnesium oxide in S2 is 1:(2-10):

1.

3. The TDI residue dissolution-pyrolysis recovery method using magnesium oxide as a catalyst and template according to claim 1, characterized in that: The absorption bottle in S3 contains ethylene glycol.

4. The TDI residue dissolution-pyrolysis recovery method using magnesium oxide as a catalyst and 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 TDI residue dissolution-pyrolysis recovery method using magnesium oxide as a catalyst and 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 TDI residue dissolution-pyrolysis recovery method using magnesium oxide as a catalyst and template according to claim 1, characterized in that: The specific surface area of ​​the refined mesoporous carbon material described in S4 is 1300 m 2 / g~1600m 2 / g.