TDI (toluene diisocynate) residue hydrolysis-pyrolysis recovery method taking lanthanum oxide as single treating agent

Abstract

The invention provides a TDI (toluene diisocynate) residue hydrolysis-pyrolysis recovery method taking lanthanum oxide as a single treating agent. The method comprises the following steps: adding ethylene glycol into crushed TDI residues, heating to 180 DEG C, keeping reflux for 0.5 hour, adding lanthanum oxide, cooling to 100 DEG C while stirring, adding deionized water, keeping constant-temperature hydrolysis reaction, cooling, discharging, and separating to obtain filtrate and filter residues; evaporating the filtrate to dryness to obtain an organic liquid phase containing toluenediamine; grinding the filter residue, and performing thermal cracking to obtain a cracked organic matter and a crude carbon material; 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 treating the thermally cracked crude carbon material with 1M hydrochloric acid or sulfuric acid, washing with water, washing with ethanol, and drying to obtain the refined mesoporous carbon material. According to the invention, lanthanum oxide with strong alkalinity is used as a single hydrolysis catalyst, the process is simpler, and the hydrolysis product is easier to detect and separate.

Description

Technical Field

[0001] The invention belongs to the technical field of TDI residue treatment, and in particular relates to a TDI residue hydrolysis-pyrolysis recovery method using lanthanum oxide as a single treatment agent. 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 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. The hydrolysis method can only treat a part of the residue (about 60%), and for the remaining residue that cannot be hydrolyzed (about 40%), it is still simply discarded without an ideal treatment method, resulting in a waste of resources and environmental pollution. The use of a strong alkaline aqueous solution of sodium hydroxide as a catalyst for the hydrolysis reaction makes it difficult to separate the hydrolysis products in the subsequent process, the process is complicated, the procedure is cumbersome, and the energy consumption is high. It also causes great difficulties in the accurate quantitative analysis of the hydrolysis products. At the same time, strong alkaline waste liquids such as sodium hydroxide will also pollute the environment. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a TDI residue hydrolysis-thermolysis recovery method using lanthanum oxide as a single treatment agent in view of the deficiencies of the above-mentioned prior art. The method uses lanthanum oxide with strong alkalinity as a single hydrolysis catalyst, the hydrolysis rate of TDI residue is high, and the hydrolysis product is easier to detect and separate. The main product in the hydrolysis process, toluenediamine, is the raw material for producing TDI.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a TDI residue hydrolysis-pyrolysis recovery method using lanthanum oxide as a single treatment agent, the method is:

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

[0008] S2, add ethylene glycol to the crushed TDI residue obtained in S1, heat to 180°C, keep reflux for 0.5h, add lanthanum oxide, cool down to 100°C while stirring, add deionized water, keep constant temperature for hydrolysis reaction for 1.5h, cool down and discharge, centrifuge or filter to obtain filtrate and residue respectively;

[0009] S3, evaporating the filtrate obtained in S2 at a temperature of 85° C. to obtain an organic liquid phase containing toluenediamine;

[0010] S4, grinding the filter residue 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 the absorption bottle and is collected as pyrolysis oil; the uncondensed gas is collected in a gas collection bag;

[0011] 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 5°C / min and the temperature was maintained for 4 h;

[0012] S5. The crude carbon material obtained after thermal cracking in S4 is sequentially subjected to acid washing to dissolve lanthanum oxide, water washing, ethanol washing, and drying to obtain a refined mesoporous carbon material.

[0013] Preferably, the mass ratio of the crushed TDI residue, ethylene glycol and lanthanum oxide in S2 is 1:(2-10):1.

[0014] Preferably, the absorption bottle in S4 contains ethylene glycol.

[0015] Preferably, the acid washing method in S5 is: adding the crude carbon material after thermal cracking, magnetic particles and 1 mol / L hydrochloric acid into a round-bottom flask equipped with a condenser reflux tube, stirring the reaction at a temperature of 90° C. for 1 hour to obtain an acid-treated carbon material.

[0016] Preferably, the drying temperature in S5 is 110° C., and the drying time is 12 h.

[0017] Preferably, the specific surface area of ​​the refined mesoporous carbon material in S5 is 1420 m 2 / g~1602m 2 / g.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. The present invention uses highly alkaline lanthanum oxide as a single hydrolysis catalyst. The hydrolysis rate of the crushed TDI residue can reach 53.5% to 61.1%. The hydrolysis product is easier to detect (organic mixture, does not contain alkali solution, can be directly analyzed by gas chromatography and liquid chromatography) and separation (can be separated by traditional distillation method). The main product TDA (toluenediamine) in the hydrolysis process is the raw material for producing TDI (toluene diisocyanate), which is more concerned by TDI manufacturers.

[0020] 2. The TDI residue hydrolysis-pyrolysis method of the present invention using lanthanum oxide as a single treatment agent can not only complete the high-yield hydrolysis process and synthesize high-surface-area mesoporous carbon materials, but also avoid the detection difficulties, separation difficulties and pollution problems caused by the sodium hydroxide hydrolysis catalyst, which is a great technical advancement.

[0021] The present invention is further described in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0022] Example 1

[0023] The TDI residue hydrolysis-pyrolysis recovery method using lanthanum oxide as a single treatment agent in this embodiment is as follows:

[0024] S1, grinding and crushing TDI residue to obtain crushed TDI residue;

[0025] S2, add 100g of ethylene glycol to 10g of the crushed TDI residue obtained in S1, heat to 180°C, keep reflux for 0.5h, add 10g of lanthanum oxide, cool to 100°C while stirring, add 10g of deionized water, keep constant temperature for hydrolysis reaction for 1.5h, cool and discharge, centrifuge to obtain filtrate and residue respectively;

[0026] S3, evaporate the filtrate obtained in S2 at 85°C for 12 h to dry the water, and obtain an ethylene glycol solution (106.2 g) containing toluene diamine (TDA) and other organic substances; gas chromatography analysis showed that it contained 5.8 g of TDA;

[0027] S4, grinding the filter residue obtained in S2, and then performing thermal cracking to obtain a crude carbon material after thermal cracking (12.5 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;

[0028] The main components of pyrolysis oil are: toluene, m-xylene, 4-ethyltoluene, etc.

[0029] The main components of the uncondensed gas are methane, ethane, hydrogen, etc.;

[0030] 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 5 °C / min and kept at a constant temperature for 4 h;

[0031] S5, the crude carbon material after thermal cracking obtained in S4 was acid-washed to dissolve lanthanum oxide, washed with water, washed with ethanol, and dried at 110°C for 12 hours to obtain a specific surface area of ​​1602m 2 / g of refined mesoporous carbon material (2.4g);

[0032] The acid washing method is: adding the crude carbon material after thermal cracking, a magnet and 450 mL of 1 mol / L hydrochloric acid into a 500 mL 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.

[0033] This embodiment uses lanthanum oxide with strong alkalinity as the single hydrolysis catalyst. The hydrolysis rate of the crushed TDI residue can reach 61.1% (calculated on the basis of TDI residue), and the hydrolysis product is easier to detect and separate.

[0034] The main product TDA (toluenediamine) in the hydrolysis process of this embodiment is the raw material for producing TDI (toluene diisocyanate), and is more concerned by TDI manufacturers.

[0035] Example 2

[0036] The TDI residue hydrolysis-pyrolysis recovery method using lanthanum oxide as a single treatment agent in this embodiment is as follows:

[0037] S1, grinding and crushing TDI residue to obtain crushed TDI residue;

[0038] S2, add 20g of ethylene glycol to 10g of the crushed TDI residue obtained in S1, heat to 180°C, keep reflux for 0.5h, add 10g of lanthanum oxide, cool to 100°C while stirring, add 10g of deionized water, keep constant temperature for hydrolysis reaction for 1.5h, cool down and discharge, filter and separate, and obtain filtrate and filter residue respectively;

[0039] S3, evaporate the filtrate obtained in S2 at 85°C for 12 hours to dryness, and obtain an ethylene glycol solution (25.5 g) containing toluene diamine (TDA) and other organic substances; gas chromatography analysis showed that it contained 5.1 g of TDA;

[0040] S4, grinding the filter residue obtained in S2, and then performing thermal cracking to obtain a crude carbon material after thermal cracking (12.8 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;

[0041] The main components of pyrolysis oil are: toluene, m-xylene, 4-ethyltoluene, etc.

[0042] The main components of the uncondensed gas are methane, ethane, hydrogen, etc.;

[0043] 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 5 °C / min and kept at a constant temperature for 4 h;

[0044] S5, the crude carbon material after thermal cracking obtained in S4 was acid-washed to dissolve lanthanum oxide, washed with water, washed with ethanol, and dried at 110°C for 24 hours to obtain a specific surface area of ​​1420m 2 / g of refined mesoporous carbon material (2.7g);

[0045] The acid washing method is: adding the crude carbon material after thermal cracking, a magnet and 450 mL of 1 mol / L hydrochloric acid into a 500 mL 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.

[0046] This example uses lanthanum oxide with strong alkalinity as the single hydrolysis catalyst, and the hydrolysis rate of the crushed TDI residue is 53.5% (based on the TDI residue).

[0047] The present invention adopts lanthanum oxide with strong alkalinity as a single hydrolysis catalyst. The hydrolysis rate of TDI residue is equivalent to that of a mixed catalytic system using sodium hydroxide and magnesium oxide (or triethylenetetramine, etc.), but the process is simpler and the hydrolysis product is easier to detect and separate.

[0048] 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 hydrolysis-pyrolysis recovery method using lanthanum oxide as a single treatment agent, characterized in that: The method is: S1, grinding and crushing TDI residue to obtain crushed TDI residue; S2, add ethylene glycol to the crushed TDI residue obtained in S1, heat to 180°C, keep reflux for 0.5h, add lanthanum oxide, cool down to 100°C while stirring, add deionized water, keep constant temperature for hydrolysis reaction for 1.5h, cool down and discharge, centrifuge or filter to obtain filtrate and residue respectively; S3, evaporating the filtrate obtained in S2 at a temperature of 85° C. to obtain an organic liquid phase containing toluenediamine; S4, grinding the filter residue 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 the 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 5°C / min and the temperature was maintained for 4 h; S5. The crude carbon material obtained after thermal cracking in S4 is sequentially subjected to acid washing to dissolve lanthanum oxide, water washing, ethanol washing, and drying to obtain a refined mesoporous carbon material.

2. The TDI residue hydrolysis-pyrolysis recovery method using lanthanum oxide as a single treatment agent according to claim 1, characterized in that: The mass ratio of the crushed TDI residue, ethylene glycol and lanthanum oxide in S2 is 1:(2-10):

1.

3. The TDI residue hydrolysis-pyrolysis recovery method using lanthanum oxide as a single treatment agent according to claim 1, characterized in that: The absorption bottle in S4 contains ethylene glycol.

4. The TDI residue hydrolysis-pyrolysis recovery method using lanthanum oxide as a single treatment agent according to claim 1, characterized in that: The acid washing method described in S5 is: adding the crude carbon material after thermal cracking, magnetic particles and 1 mol / L 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 hydrolysis-pyrolysis recovery method using lanthanum oxide as a single treatment agent according to claim 1, characterized in that: The drying temperature in S5 is 110° C., and the drying time is 12 h.

6. The TDI residue hydrolysis-pyrolysis recovery method using lanthanum oxide as a single treatment agent according to claim 1, characterized in that: The specific surface area of ​​the refined mesoporous carbon material described in S5 is 1420 m 2 / g~1602m 2 / g.