Wanhua Chemical (ningbo) Co., Ltd.

Beijing University of Chemical Tehcnology

Wanhua Chemical Group Co., Ltd.

Ningbo Wanhua Polyurethanes Co., Ltd.

Wanhua Chemical Co., Ltd.

Shuchang Sun

Weiqi Hua

Jianfeng Chen

Hongke Zhang

Guangwen Chu

Jiansheng Ding

Haikui Zou

Limin Xu

Pengyuan Zhang

Yuan Li

Yonghua Shang

Qiang Li

Jing Li

Xiaogao Liu

Wenbin Li

Jingxu Wang

Jinping Han

Tonghe Li

Zhenhua Zhao

Pengfei Wang

A method for preparing an isocyanate in a gaseous phase by feeding, in the presence or absence of an inert gas, an amine-containing gas stream and a phosgene-containing gas stream into a reaction region, allowing the amine and the phosgene to contact in gaseous forms and undergo a phosgenation reaction in the reaction region, thus preparing the target isocyanate in a gaseous form in the reaction region. The phosgene-containing stream is subjected to preheating and warming before being fed into the reaction region, and the phosgene-containing stream comprises a substance A at a mass fraction of &#x3c;1% before being subjected to the preheating and warming up. Substance A is a NCO group-containing substance and/or an olefinic double bond-containing substance. The method reduces the formation of clogging matter in a heat exchanger and a vessel during the preheating and warming of the phosgene and during the reaction process.

Method for preparing isocyanate in gaseous phase

The invention relates to a method of circular use of waste brine produced in the manufacture process of MDI, comprising the following steps: (1) the waste brine produced in the manufacture process of MDI is subjected to a high-gravity extraction and then to a column extraction, wherein said waste brine contains aniline, diaminodiphenylmethane and polyamine; (2) the waste brine from step (1) is transmitted to a stripping tower for steam stripping; (3) the waste brine from the stripping tower of step (2) and a chemical oxidant are transmitted to an oxidation reactor to which air is blown for aeration; (4) the waste brine after the treatment of step (3) is transmitted to an absorption tower for absorption. The invention makes the salt water have TOC of less than 8 ppm and TN of less than 2.5 ppm and achieves regeneration of resources in the waste brine such as sodium chloride and water and the like for circular use.

Method for treating waste saline water produced in production process of diphenylmethane diisocyanate (MDI)

The present invention provides a method of preparing polymethylene-polyphenyl-polyamine (briefly referred to as polyamine, DAM), in which a high gravity rotating bed is used as the mixing reactor of formaldehyde and aniline hydrochloride, the mixing solution of aniline hydrochloride and circulation solution and the formaldehyde are fed into the high gravity rotating bed reactor proportionally to carry out mixing and condensation reaction under a condition of a very high gravity; the materials leaving the high gravity rotating bed reactor is introduced into a stirred vessel to proceed with the pre-condensation reaction and obtain a condensation solution; and the process steps of heating, molecular rearrangement, neutralization, water washing and purification, etc. are completed to obtain the refined DAM. With the method according to the present invention, the main by-products is obviously reduced in the condensation process, the phenomenon of deposit attaching to the inner walls of circulation pipes and heat exchanger and blockage are prevented in the condensation process, the impurity content is low in the refined DAM, and the subsequent product MDI has a lighter color, the product quality is stable and may be improved to a certain extent.

Method of preparing polymethylene-polyphenyl-polyamine

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Zhejiang, China

Shuchang Sun