Separation and purification device and method for preparing methylene diphenyl diisocyanate (MDI) complex product by utilizing pyrolysis of carbamate

A carbamate and refining device technology, which is applied in the field of separation and refining devices for preparing MDI complex products by carbamate pyrolysis, can solve the problems affecting the purity of the target product MDI, coking, and the temperature of the separation system cannot be too high, and achieves the realization of The effect of continuous operation of the process, small investment in equipment and equipment, and simple process

CN102675154BActive Publication Date: 2013-11-06INST OF PROCESS ENG CHINESE ACAD OF SCI
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2013-11-06

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Abstract

The invention relates to a separation and purification device and a method for preparing an MDI complex product by utilizing pyrolysis of carbamate. The separation and purification device comprises a solvent dehydration tower (2), a cooling and crystallization system (4), a heat filter (5) and a de-heavy fractionator (6), reboilers (3) are arranged at the bottoms of the solvent dehydration tower (2) and the de-heavy fractionator (6) respectively, and condensers (1) are arranged at the tops of the solvent dehydration tower (2) and the de-heavy fractionator (6) respectively. The method includes adding a mixing material containing solvents, raw materials, by-products and the MDI product to the solvent dehydration tower (2) for rectification and separation so as to achieve recycling of the solvents, adding the obtained liquid containing the MDI product to the cooling and crystallization system (4) for cooling and crystallization, obtaining a part of the raw materials, by-product solid and filtrate containing the MDI product after the filtration of the heat filter (5), and adding the filtrate to the de-heavy fractionator (6) for separation to obtain the MDI product. The separation and purification device and the method for preparing the MDI complex product by utilizing the pyrolysis of carbamate have the advantages of being simple in process, easy to operate and capable of achieving continuous operation.
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Description

technical field

[0001] The invention relates to the field of separation of MDI, in particular, the invention relates to a separation and refining device and method for preparing complex MDI products by pyrolysis of carbamate. Background technique

[0002] Diphenylmethane diisocyanate (MDI for short) is the main basic raw material of polyurethane industry. According to the different positions of the two -NCO groups on the benzene ring, there can be three isomers of 2,2'-MDI, 2,4'-MDI and 4,4'-MDI.

[0003] At present, the production of MDI at home and abroad mainly adopts the phosgene method to prepare diphenylmethane-based diamines and polyamines through the condensation reaction of aniline and formaldehyde, and then prepare diphenylmethane-based diisocyanates (MDI) through the phosgene reaction. and polyisocyanates. Due to the introduction of phosgene, there are chlorine-containing compounds in the product system, in addition to three isomers of MDI, polyisocyanates and l...

Examples

Embodiment 1

[0036]

[0037] In Example 1, 664g of stream a comprising 2,2'-MDI, 2,4'-MDI, 4,4'-MDI, MMI, MDC, and chlorobenzene was weighed, and the stream was passed through the desolventizer Chlorobenzene content in c is reduced to 3.16%, and stream c is through cooling crystallization and thermal filtration system, and MMI and MDC content are respectively reduced to 13.7%, 4.97% in stream d of gained, after stream d passes through weight-removing tower, gained stream Stream f is composed of chlorobenzene and methanol, which are not detected, and stream g is a mixture of high-purity MDI isomers with a purity of 97%.

Embodiment 2

[0039]

[0040] In Example 2, 616.8 g of stream a comprising 2,2'-MDI, 2,4'-MDI, 4,4'-MDI, MMI, MDC, and chlorobenzene were weighed and passed through the desolventizing tower. The chlorobenzene content in the strand c is reduced to 2.79%, and the stream c is passed through the cooling crystallization and thermal filtration system, and the MMI and MDC contents are respectively reduced to 9.07%, 0.57% in the gained stream d, and after the stream d passes through the weight-removing tower, the obtained Stream f is composed of chlorobenzene and methanol, which are not detected, and stream g is a mixture of high-purity MDI isomers with a purity of 96.8%.

[0041] The invention provides a separation and purification device and method for preparing MDI complex products by pyrolysis of carbamate, which realizes the separation and purification of complex product systems in the process of preparing MDI by pyrolysis of carbamate, and solves the problem of preparing MDI by previous met...