Method for producing diphosgene or triphosgene from phosgene

Abstract

The invention provides a method for producing diphosgene or triphosgene from phosgene. The method comprises the following steps: preparing a solution, performing solution decontamination, performing catalytic decomposition, performing phosgene refining and recycling a solvent. A diphosgene or triphosgene solution is adopted to contact and react with a catalyst, and the reaction velocity can be flexibility controlled by controlling the concentration of the solution. Before contacting the catalyst, the diphosgene or triphosgene solution is firstly purified, catalyst poisoning is avoided, the service life of the catalyst is prolonged, and the cost is lowered. Moisture and the solvent mixed with phosgene are removed by using a phosgene decomposition refining tower, so that the situations that side reactions and equipment erosion are increased as moisture carried in the solvent and raw materials is fed into a phosgene use unit along with the phosgene can be avoided.

Description

technical field [0001] The invention belongs to the field of phosgene preparation, in particular to a method for producing phosgene from diphosgene or triphosgene. Background technique [0002] As the most economical carbonylation reagent, phosgene has been widely used in the synthesis of medicines, pesticides and new materials, and as one of the main raw materials in the above industries, it has become an indispensable raw material for the modern chemical industry. However, the highly toxic properties of phosgene have become a huge obstacle restricting its application. With the gradual deepening and strengthening of the country's environmental protection and safety management, the industrial synthesis and application of phosgene have gradually concentrated in the production process of isocyanate, PC and main pesticide intermediates. The production of niche carbonylation products mainly relies on diphosgene and triphosgene. In some individual processes, diphosgene and trip...

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Problems solved by technology

[0003] The existing phosgene preparation method has the following disadvantages: 1. Catalyzing and decomposing liquid diphosgene or solid triphosgene at room temperature requires a relatively special catalyst. The screening process of the catalyst is very complicated and long, and the catalyst cost is very high; 2. .In the state of heating and heating, ordinary catalysts can be used to catalyze the decomposition of liquid diphosgene or molten triphosgene, but the toxicity of diphosgene and the violent gasification and sublimation of molten triphosgene will constitute a major source of danger, and the latter is fundamentally Uncontrollable; 3. In the process of directly using ordinary catalysts to catalyze the decomposition of diphosgene and triphosgene, the catalyst will lose its catalytic activity in just 4-6 hours; 4. Since triphosgene has very strong water absorption, it is In the process of catalytic decomposition of triphosgene, phosgene will carry more water, and the amount of water content is related to the storage time of triphosgene. The water content of triphosgene is > 0.5w% when it leaves the factory, and the longer the storage time, the more water content; The carbonylation reaction often produces hydrogen chloride gas, and the presence of moisture will cause large-scale equipment corrosion

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