CN113996280B - Solid base catalyst for hydrolyzing TDI tar residues and application thereof - Google Patents

Abstract

The invention discloses a solid base catalyst for hydrolyzing TDI tar residues and application thereof. The solid base catalyst is prepared by combining an impregnation method and an ultrasonic technology, and the general formula of the solid base catalyst is M ₂ O ₃ CaO, wherein M is lanthanum, cerium or zirconium. The method for recovering Toluenediamine (TDA) by hydrolyzing Toluene Diisocyanate (TDI) tar residues by adopting the solid base catalyst comprises the following steps: after the TDI tar residue is ground, glycol is used as a solvent, a solid base catalyst is adopted for hydrolysis under normal pressure, and the TDI tar residue can be hydrolyzed and important industrial raw material TDA can be recycled without any additional high pressure, so that more effective comprehensive recycling treatment is achieved, and the reduction and harmless treatment targets are achieved.

Description

A kind of solid base catalyst of hydrolysis TDI tar residue and application thereof

technical field

The invention belongs to the technical field of TDI tar residue treatment, and in particular relates to a solid base catalyst for hydrolyzing TDI tar residue and its application as an atmospheric pressure hydrolysis catalyst in treating TDI tar residue and recovering TDA.

Background technique

Toluene diisocyanate (TDI) is one of the main raw materials in the polyurethane industry. It is mainly used to prepare polyurethane soft foam, hard foam, adhesives, coatings and elastomers. It is also used for surface processing of natural rubber and textile processing, etc. aspect. It is mainly produced by the toluene diamine (TDA) phosgene method. The isocyanate functional group of TDI has quite high reactivity and can react with various substances containing active hydrogen (such as water, alcohol, amine, etc.), resulting in the generation of a large amount of tar residue by-products. The by-products of TDI tar residue have complex components, the main components are polyurea and polybiuret, and contain a small amount of TDI and tar, as well as a small amount of carbodiimide and allophanate.

The simple ways to deal with TDI tar residue are landfill and incineration, but these two methods do not meet the requirements of today's green environmental protection. Landfill needs to occupy land, while incineration will produce a large amount of _CO2 and nitrogen oxides, which are harmful to the environment. produce secondary pollution.

Distillation treatment of TDI residue to recover some chemical raw materials is a widely used method to solve the residue. It has been reported that methyl o-phenylenediamine is extracted from TDI hydrogenated organic residues by dissolving TDI organic residues and vacuum purification rectification, then reacting it with excess sodium nitrite solution, and then acidifying, rinsing, vacuum dehydrating, refining Distillation and purification to make tolutriazole products. There is also effective treatment of TDI tar residue by mixing TDI tar residue with diphenylmethane diisocyanate and converting part of it into polyurethane by distillation. However, the method of distillation treatment has higher requirements on equipment, temperature and pressure.

Hydrolysis treatment of TDI residue is a more advanced method at present. It has been reported that under the condition of caustic soda catalyzed hydrolysis, adding a high boiling point solvent, the residue of TDI under normal pressure can be hydrolyzed to obtain 2,4-diaminotoluene product; Diethyl formate (DEIP) yields isophthalic acid (IPA) product.

The existing TDI tar residue hydrolysis technology to prepare TDA mostly uses liquid alkali catalysts, and is carried out under high temperature and high pressure conditions, which requires a pressure-resistant closed reactor, high production equipment costs, and also consumes a large amount of soluble inorganic alkali, which is easy to corrode production The equipment produces a large amount of waste water, which is difficult to separate and recycle in the later stage. So far, the hydrolysis and chemical industrial treatment has not been realized, so that most of the TDI tar residue is still deeply buried.

Therefore, according to the characteristics of the main components of TDI tar residue, how to solve the problems of high temperature and high pressure conditions for hydrolysis, large hydrolysis mass transfer resistance under normal pressure conditions, large amounts of waste water, and difficult recycling of catalysts have become the key to the hydrolysis chemical industry. .

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, provide a solid base catalyst for hydrolyzing TDI tar residue and its application, solve the problem of harsh conditions in the method for processing TDI tar residue in the above-mentioned background technology, and also solve the problem of liquid The problems in the application of alkali catalysts have realized the hydrolysis and chemical industrial treatment of TDI tar residue.

One of the technical solutions adopted by the present invention to solve the technical problems is: a solid base catalyst for hydrolyzing TDI tar residue is provided, the general formula of the solid base catalyst is M ₂ O ₃ /CaO, wherein M is lanthanum, cerium or zirconium.

In a preferred embodiment of the present invention, the preparation method comprises the following steps:

(1) CaO is placed in the Erlenmeyer flask, add deionized water and stir;

(2) Configure the aqueous nitrate solution of M, pour it into the Erlenmeyer flask containing CaO in (1) and stir to obtain a mixed liquid; wherein, the M:Ca molar ratio is 0.05 to 0.5;

(3) Place the mixed liquid obtained in (2) in an ultrasonic cleaner for 20 to 30 minutes;

(4) Place it in an oven at 80°C for overnight drying, then place it in a constant temperature muffle furnace for calcination for 3 hours at a calcination temperature of 700-950°C, and collect the product, namely M ₂ O ₃ /CaO solid base catalyst.

In a preferred embodiment of the present invention, the M:Ca molar ratio in the step (2) is 0.1-0.25.

In a preferred embodiment of the present invention, the calcination temperature in the step (4) is 800-900°C.

The second technical solution adopted by the present invention to solve the technical problem is to provide the application of the above-mentioned solid base catalyst for recovering TDA by hydrolyzing TDI tar residue under normal pressure conditions. Specifically include the following steps:

(1) Grind the TDI tar residue raw material into powder, weigh the TDI tar residue powder and place it in an oil bath with a stirring device, add ethylene glycol solvent at a solid-to-liquid ratio of 1:1-20kg/L, and heat at 180°C Condensate and reflux for 70 minutes to obtain a solid-liquid mixture A containing TDI tar residue;

(2) Cool down the solid-liquid mixture A to 80-140°C, add a solid base catalyst for hydrolysis reaction for 3-11 hours to obtain the hydrolyzed solid-liquid mixture B, and cool to normal temperature;

(3) Separating the hydrolyzed solid-liquid mixture B into solid-liquid to obtain the hydrolyzed filtrate and the solid base catalyst respectively, washing the solid base catalyst several times with absolute ethanol, and recovering after drying.

In a preferred embodiment of the present invention, in the step (2), the temperature of the solid-liquid mixture A is lowered to 100-120°C.

In a preferred embodiment of the present invention, the solid base catalyst is in powder form, and the dosage is 10-90% of the TDI tar residue powder.

In a preferred embodiment of the present invention, the amount of the solid base catalyst is 30-70% of the TDI tar residue powder.

In a preferred embodiment of the present invention, in the step (2), the hydrolysis reaction time is 5-9 hours.

Compared with the background technology, this technical solution has the following advantages:

1. The present invention is based on the principle of alkaline hydrolysis of TDI tar residue, that is, the nucleophilic addition reaction of oxygen-containing anions (hydroxide ions or alkoxy anions) to specific functional groups (urea groups or ester groups), using heterogeneous solids The basic catalyst replaces the traditional homogeneous soluble alkali catalyst, optimizes the hydrolysis process, and overcomes the defects of harsh conditions, high cost, complicated process, and secondary pollution caused by the treatment process in the existing methods for treating TDI tar residue.

2. The solid base catalyst of the present invention is easy to separate from the product, does not generate a large amount of waste water during the treatment process, and can be recycled multiple times, showing obvious advantages for continuous industrial production. While effectively hydrolyzing TDI tar residue into TDA, it can realize The recycling of the catalyst reduces the difficulty and cost of the process.

3. The present invention can not only realize the low-cost, rapid, gentle and effective hydrolysis of TDI tar residue, but also realize the environmental protection concept of no waste water discharge and catalyst recycling.

detailed description

Example 1

In this example, a La ₂ O ₃ /CaO solid base catalyst, the preparation method is as follows:

Weigh 2g of CaO and place it in a conical flask, add deionized water and stir; configure La(NO ₃ ) ₃ aqueous solution to meet the La:Ca molar ratio of 0.2, pour La(NO ₃ ) ₃ aqueous solution into the above-mentioned Stir in a Erlenmeyer flask of CaO at room temperature; place the obtained white turbid liquid in a 100w power ultrasonic cleaner for 30 minutes; put it in an oven at 80°C and dry it overnight, then place it in a constant temperature muffle furnace at 850°C for calcination for 3 hours, and collect the product. That is, La ₂ O ₃ /CaO solid base catalyst, which is ground into powder and stored in an airtight container.

Using the solid alkali catalyst of this embodiment to hydrolyze the TDI tar residue to reclaim TDA, the specific steps are as follows:

Grind the TDI tar residue into a powder with a particle size of 80 mesh. Weigh 1g of TDI powder and place it in an oil bath with a reflux device, add ethylene glycol solvent at a solid-to-liquid ratio of 1:20 (kg/L), condense and reflux at 180°C for 70 minutes, and obtain a mixture containing TDI tar residue a. The temperature of the oil bath was lowered to 110° C., and 0.5 g (50%, mass fraction) of La ₂ O ₃ /CaO solid base catalyst was added, and the hydrolysis reaction was carried out for 7 hours to obtain a hydrolysis mixture B. After the reaction was completed, it was cooled to room temperature and centrifuged to obtain the hydrolysis filtrate and catalyst. The yield of toluenediamine was 31.02% as detected by liquid chromatography. Use a small amount of absolute ethanol to wash the catalyst for 3 to 5 times, dry it and set it aside. After the catalyst is recycled three times, the yield of TDA still maintains the initial 86%, which has good cycle performance.

Example 2

In this example, La(NO ₃ ) ₃ was replaced by Ce(NO ₃ ) ₃ during the preparation of the solid base catalyst, and other preparation conditions were the same as in Example 1 to prepare the Ce ₂ O ₃ /CaO solid base catalyst. The hydrolysis conditions of TDI tar residue are the same as in Example 1, and the yield of p-toluenediamine was quantitatively tested, and the yield was measured to be 21.78%.

Example 3

In this example, La(NO ₃ ) ₃ was replaced by Zr(NO ₃ ) ₃ during the preparation of the solid base catalyst, and other preparation conditions were the same as in Example 1 to prepare the Zr ₂ O ₃ /CaO solid base catalyst. The hydrolysis conditions of TDI tar residue are the same as in Example 1, and the yield of p-toluenediamine was quantitatively tested, and the yield was measured to be 20.79%.

Example 4

In this example, the La:Ca molar ratio was changed to 0.15 during the preparation of the solid base catalyst, and other preparation conditions were the same as in Example 1. The hydrolysis conditions were the same as in Example 1, and the yield of p-toluenediamine was quantitatively tested, and the measured yield was 25.52%.

Example 5

In this example, the La:Ca molar ratio was changed to 0.25 during the preparation of the solid base catalyst, and other preparation conditions were the same as in Example 1. The hydrolysis conditions were the same as in Example 1, and the yield of p-toluenediamine was quantitatively tested, and the measured yield was 26.75%.

Example 6

In this example, the calcination temperature was changed to 800° C. during the preparation of the solid base catalyst, and other preparation conditions were the same as in Example 1. The hydrolysis conditions were the same as in Example 1, and the yield of p-toluenediamine was quantitatively tested, and the measured yield was 30.44%.

Example 7

In this example, the calcination temperature was changed to 900° C. during the preparation of the solid base catalyst, and other preparation conditions were the same as in Example 1. The hydrolysis conditions were the same as in Example 1, and the yield of p-toluenediamine was quantitatively tested, and the measured yield was 30.51%.

Example 8

In this embodiment, the solid base catalyst of Example 1 is used, and when the TDI tar residue is hydrolyzed, the cooling temperature of the oil bath is changed to 90° C., and other conditions are the same as in Example 1. The yield of p-toluenediamine is quantitatively tested. The yield was 22.46%.

Example 9

In this example, the solid base catalyst of Example 1 is used, and when the TDI tar residue is hydrolyzed, the cooling temperature of the oil bath is changed to 130° C., and other conditions are the same as in Example 1. The yield of p-toluenediamine is quantitatively tested. The yield was 28.01%.

Example 10

This embodiment adopts the solid base catalyst of embodiment 1, when the hydrolysis of TDI tar residue, the catalyst addition is changed into 0.3g, other conditions are the same as embodiment 1, the productive rate quantitative test of p-toluenediamine, records the yield The rate is 28.65%.

Example 11

This embodiment adopts the solid base catalyst of embodiment 1, when the hydrolysis of TDI tar residue, the catalyst addition amount is changed into 0.7g, other conditions are the same as embodiment 1, the productive rate quantitative test of p-toluenediamine, records the yield The rate is 29.84%.

Example 12

This embodiment is adopting the solid base catalyst of embodiment 1, when the hydrolysis of TDI tar residue, the holding time is changed into 5h, other conditions are the same as embodiment 1, the productive rate quantitative test of p-toluenediamine, record productive rate as 26.46%.

Example 13

This embodiment adopts the solid base catalyst of embodiment 1, when the hydrolysis of TDI tar residue, change the holding time to 9h, other conditions are the same as embodiment 1, the productive rate quantitative test of p-toluenediamine, record productive rate as 28.20%.

The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be applied to the foregoing embodiments Modifications are made to the recorded technical solutions, or equivalent replacements are made to some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (8)

1. The application of a solid base catalyst, characterized in that: it is used to hydrolyze TDI tar residue under normal pressure conditions to reclaim TDA, the general formula of the solid base catalyst is M ₂ O ₃ /CaO, wherein M is lanthanum, cerium or zirconium; The preparation method of described solid base catalyst comprises the steps: (1) CaO is placed in the Erlenmeyer flask, add deionized water and stir; (2) Configure the aqueous nitrate solution of M, pour it into the Erlenmeyer flask containing CaO in (1) and stir to obtain a mixed liquid; wherein, the M:Ca molar ratio is 0.05 to 0.5; (3) Place the mixed liquid obtained in (2) in an ultrasonic cleaner for 20 to 30 minutes; (4) Place it in an oven at 80°C for overnight drying, then place it in a constant temperature muffle furnace for calcination for 3 hours at a calcination temperature of 700-950°C, and collect the product, namely M ₂ O ₃ /CaO solid base catalyst. 2. The application of a solid base catalyst according to claim 1, characterized in that: in the step (2), the molar ratio of M:Ca is 0.1-0.25. 3. The application of a solid base catalyst according to claim 2, characterized in that: the calcination temperature in the step (4) is 800-900°C. 4. the application of a kind of solid base catalyst according to claim 1, is characterized in that: comprise the steps: (1) Grind the TDI tar residue raw material into powder, weigh the TDI tar residue powder and place it in an oil bath with a stirring device, add ethylene glycol solvent at a solid-to-liquid ratio of 1:1-20kg/L, and heat at 180°C Condensate and reflux for 70 minutes to obtain a solid-liquid mixture A containing TDI tar residue; (2) Cool down the solid-liquid mixture A to 80-140°C, add a solid base catalyst for hydrolysis reaction for 3-11 hours to obtain the hydrolyzed solid-liquid mixture B, and cool to normal temperature; (3) Separating the hydrolyzed solid-liquid mixture B into solid-liquid to obtain the hydrolyzed filtrate and the solid base catalyst respectively, washing the solid base catalyst several times with absolute ethanol, and recovering after drying. 5. The application of a solid base catalyst according to claim 4, characterized in that in the step (2), the temperature of the solid-liquid mixture A is lowered to 100-120°C. 6. The application of a solid base catalyst according to claim 4, characterized in that: the solid base catalyst is in powder form, and the dosage is 10-90% of the TDI tar residue powder. 7. The application of a solid base catalyst according to claim 4, characterized in that: the amount of the solid base catalyst is 30-70% of the TDI tar residue powder. 8. The application of a solid base catalyst according to claim 4, characterized in that: in the step (2), the hydrolysis reaction time is 5-9 hours.