CN110511132A - A kind of TDI residue hydrolysis method using dolomite as catalyst - Google Patents

Abstract

The invention provides a method for hydrolyzing TDI residue using dolomite as a catalyst, comprising the following steps: S1, pulverizing the solid residue of TDI; S2, using ethylene glycol as the reaction medium, adding the TDI residue, wherein the TDI residue and ethylene The mass ratio of diol is 1:20～1:25, and then heated to reflux, wherein the reflux temperature is 180-200°C, and the reflux time is 0.5～2h to dissolve the TDI residue to obtain the TDI residue ethylene glycol mixture; S3, to TDI Add dolomite and sodium hydroxide solution to the residue ethylene glycol mixture to carry out hydrolysis reaction; S4, filter, dry and weigh the reaction product, and calculate its hydrolysis yield. Compared with the traditional conditions for the decomposition of TDI residues in a supercritical state, the present invention can complete the decomposition reaction of TDI residues under mild conditions, which reduces the loss of equipment and improves the safety of equipment at the same time The catalyst of this method is cheap and common, and the hydrolysis yield is also higher than the traditional method, which is convenient for the environmental protection hydrolysis treatment of TDI residue.

Description

A kind of TDI residue hydrolysis method using dolomite as catalyst

technical field

The invention belongs to the technical field of hydrolysis of TDI residues, and in particular relates to a method for hydrolysis of TDI residues using dolomite as a catalyst.

Background technique

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 the high level of science and technology, it is also internationally recognized as "two big and one high" products. Its products are widely used in home, Construction, automotive, coatings. Polyurethane is one of the six promising synthetic materials in the world. It has the functions of wear resistance, low temperature resistance, oil resistance and ozone resistance. It has achieved rapid development in my country in recent years. Toluene diisocyanate (TDI), as one of the main raw materials in 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.

Isophthalic acid is mainly used in unsaturated polyester resin, PET copolymer resin, alkyd resin and other applications. my country's consumption of unsaturated polyester resins reaches 440,000 tons, of which about 50,000 tons of isophthalic acid-type unsaturated polyesters require about 10,000 tons of isophthalic acid.

During the reaction process of synthesizing TDI, TDI is very prone to polymerization reaction to generate a kind of tar mainly composed of urea compounds. This kind of tar has certain heat sensitivity, especially when the TDI contained in the tar is evaporated, it is more prone to puffing, that is, it instantly becomes a solid with honeycomb voids. At present, in the TDI production process, a rectification tower is used to distill the product from the top of the tower, and the bottom of the tower bottom containing a certain amount of TDI and tar is discharged from the bottom of the rectification tower. At the bottom of the rectifying tower, new tar will be further generated due to reasons such as high operating temperature and long residence time. In order to ensure the continuous and stable operation of the reboiler at the bottom of the distillation column, at least 50% TDI must be kept in the bottom tar, otherwise the reboiler is easy to coke and block, resulting in accidental shutdown.

However, in the production process of toluene diisocyanate, tar waste is generated as a by-product, and in the past, it was landfilled or thrown into the ocean, causing soil pollution and water pollution. In addition, incineration is the treatment method for misplaced waste, and the production of nitrogen oxides, sulfur oxides, and dioxins during incineration causes environmental problems second only to landfill or dumping into the ocean, which affects the decomposition and treatment of TDI residues.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for hydrolysis of TDI residue using dolomite as a catalyst to solve the problem of environmental pollution caused by TD residue treatment proposed in the background technology above.

For solving the problems of the technologies described above, the technical solution adopted in the present invention is: a kind of TDI residue hydrolysis method using dolomite as catalyzer, comprises the following steps:

S1, pulverizing the solid residue of TDI;

S2. Using ethylene glycol as the reaction medium, add TDI residue, wherein the mass ratio of TDI residue to ethylene glycol is 1:20 to 1:25, and then heat to reflux, wherein the reflux temperature is 180-200°C, and the reflux time is Dissolve the TDI residue in 0.5-2 hours to obtain the TDI residue ethylene glycol mixture;

S3, adding dolomite and sodium hydroxide solution to the TDI residue ethylene glycol mixture to carry out hydrolysis reaction;

S4. Filter, dry and weigh the reaction product, and calculate its hydrolysis yield.

Preferably, in S3, the dolomite is specifically calcined at 800° C. for 3 hours.

Preferably, the sodium hydroxide solution in S3 is specifically prepared by dissolving 5 g of sodium hydroxide in 20 ml of distilled water.

Preferably, the reaction temperature in S3 is 90-100° C., and the reaction time is 5-7 hours.

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

Compared with the traditional conditions for the decomposition of TDI residues in a supercritical state, the present invention can complete the decomposition reaction of TDI residues under mild conditions, which reduces the loss of equipment and improves the safety of equipment at the same time The catalyst of this method is cheap and common, and the hydrolysis yield is also higher than the traditional method, the hydrolysis yield can reach 69%, and the raw material of high industrial value, TDI, is also included in the hydrolysis product. It can realize waste reuse and recycling to a greater extent, and facilitate the environmental protection hydrolysis of TDI residue.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Embodiment 1, the present invention provides a kind of technical scheme: a kind of TDI residue hydrolysis method using dolomite as catalyst, comprises the following steps:

S1, take by weighing 5g of TDI distillation residue after crushing and 100g of ethylene glycol for subsequent use;

S2. Using ethylene glycol as the reaction medium, add the TDI residue into a reactor with a capacity of 250mL equipped with a stirrer, a reflux condenser and a thermometer, and heat it to reflux. h, after the reflux, the temperature dropped to 90°C to obtain the TDI residue ethylene glycol mixture;

S3. Add dolomite and sodium hydroxide solution to the TDI residue ethylene glycol mixture for hydrolysis reaction, wherein the reaction temperature is 90°C, the reaction time is 7h, and the dolomite is specifically calcined at 800°C for 3h. The sodium hydroxide solution is specifically prepared by dissolving 5g of sodium hydroxide in 20ml of distilled water;

S4. Filter, dry and weigh the reaction product, and calculate its hydrolysis yield to be 64%.

Comparative Example 1, different from Example 1, in S3, add 3g of triethylenetetramine and 20ml of sodium hydroxide solution to the TDI residue ethylene glycol mixture, then the same reaction product is filtered, dried and weighed , Calculate its hydrolysis yield to be 60%.

Comparative Example 2, different from Example 1, in S3, sodium hydroxide solution is added to the TDI residue ethylene glycol mixed solution, the same reaction product is filtered, dried and weighed, and its hydrolysis yield is calculated to be 30 %.

Comparing the final hydrolysis yield of Comparative Example 1 with Example 1, the traditional triethylamine catalyst and sodium hydroxide mixed catalyst, although the hydrolysis yield can reach 60%, the cost of triethylamine is higher than that of dolomite. Expensive a lot, use triethylamine catalyst to increase the cost input of hydrolysis process, inconvenient to use in large quantities; The hydrolysis yield that can obtain independent sodium hydroxide catalyst only has 30% by comparing the final hydrolysis yield of comparative example 1 with embodiment 1 , the hydrolysis efficiency is low, which is not conducive to the hydrolysis treatment of TDI residue.

Embodiment 2, the present invention provides a kind of technical scheme: a kind of TDI residue hydrolysis method using dolomite as catalyst, comprises the following steps:

S1, take by weighing 5g of TDI distillation residue after crushing and 110g of ethylene glycol for subsequent use;

S2. Using ethylene glycol as the reaction medium, add the TDI residue into a reactor with a capacity of 250mL equipped with a stirrer, a reflux condenser and a thermometer, and heat it to reflux. h, after the reflux, the temperature dropped to 90°C to obtain the TDI residue ethylene glycol mixture;

S3. Add dolomite and sodium hydroxide solution to the TDI residue ethylene glycol mixture for hydrolysis reaction, wherein the reaction temperature is 100°C, the reaction time is 7h, and the dolomite is specifically calcined at 800°C for 3h. The sodium hydroxide solution is specifically prepared by dissolving 5g of sodium hydroxide in 20ml of distilled water;

S4. Filter, dry and weigh the reaction product, and calculate its hydrolysis yield to be 69%.

Embodiment 3, the present invention provides a kind of technical scheme: a kind of TDI residue hydrolysis method using dolomite as catalyst, comprises the following steps:

S1, take by weighing 5g of TDI distillation residue after crushing and 120g of ethylene glycol for subsequent use;

S2. Using ethylene glycol as the reaction medium, add the TDI residue into a reactor with a capacity of 250mL equipped with a stirrer, a reflux condenser and a thermometer, and heat it to reflux. h, after the reflux, the temperature dropped to 90°C to obtain the TDI residue ethylene glycol mixture;

S3. Add dolomite and sodium hydroxide solution to the TDI residue ethylene glycol mixture to carry out hydrolysis reaction, wherein the reaction temperature is 100°C, the reaction time is 5h, and the dolomite is specifically calcined at 800°C for 3h. The sodium hydroxide solution is specifically prepared by dissolving 5g of sodium hydroxide in 20ml of distilled water;

S4. Filter, dry and weigh the reaction product, and calculate its hydrolysis yield to be 62%.

Embodiment 4, the present invention provides a kind of technical scheme: a kind of TDI residue hydrolysis method using dolomite as catalyst, comprises the following steps:

S1, take by weighing 5g of TDI distillation residue after crushing and 125g of ethylene glycol for subsequent use;

S2. Using ethylene glycol as the reaction medium, add the TDI residue into a reactor with a capacity of 250mL equipped with a stirrer, a reflux condenser and a thermometer, and heat it to reflux. h, after the reflux, the temperature dropped to 90°C to obtain the TDI residue ethylene glycol mixture;

S3. Add dolomite and sodium hydroxide solution to the TDI residue ethylene glycol mixture for hydrolysis reaction, wherein the reaction temperature is 90°C, the reaction time is 5h, and the dolomite is specifically calcined at 800°C for 3h. The sodium hydroxide solution is specifically prepared by dissolving 5g of sodium hydroxide in 20ml of distilled water;

S4. Filter, dry and weigh the reaction product, and calculate its hydrolysis yield to be 59%.

In conjunction with Examples 1, 2, 3 and 4, it can be obtained that in the hydrolysis reaction process, the reaction temperature is 100°C, and the reaction time is 7h under the hydrolysis reaction conditions, the hydrolysis yield of TDI residue is the highest, reaching 69%, which is the best Implementation conditions.

It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is a relationship between these entities or operations. any such actual relationship or order exists between them. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or device.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (4)

1. a method for hydrolysis of TDI residue with dolomite as catalyzer, it is characterized in that: comprise the following steps: S1, pulverizing the solid residue of TDI; S2. Using ethylene glycol as the reaction medium, add TDI residue, wherein the mass ratio of TDI residue to ethylene glycol is 1:20 to 1:25, and then heat to reflux, wherein the reflux temperature is 180-200°C, and the reflux time is Dissolve the TDI residue in 0.5-2 hours to obtain the TDI residue ethylene glycol mixture; S3, adding dolomite and sodium hydroxide solution to the TDI residue ethylene glycol mixture to carry out hydrolysis reaction under normal pressure; S4. Filter, dry and weigh the reaction product, and calculate its hydrolysis yield. 2 . A method for hydrolyzing TDI residue using dolomite as a catalyst according to claim 1 , wherein the dolomite in S3 is specifically calcined at 800° C. for 3 h. 3 . 3. A kind of TDI residue hydrolysis method using dolomite as catalyzer according to claim 1, is characterized in that, in S3, described sodium hydroxide solution is specifically made by dissolving 5g sodium hydroxide in 20ml distilled water. 4. A method for hydrolyzing TDI residue using dolomite as a catalyst according to claim 2, characterized in that the reaction temperature in S3 is 90-100°C, and the reaction time is 5-7h.