Phosgene Production with Low-Oxide Chlorine Feed
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Solution Overview
Problem
Chlorine oxides in the chlorine feed stream cause rapid deactivation of activated carbon catalysts used in phosgene production, leading to reduced catalyst lifespan and production outages.
Innovation Solution
A process to prepare phosgene using a chlorine feed stream with a chlorine oxide content of not more than 130 ppm by volume, achieved by electrolyzing sodium chloride solution, subjecting chlorine to workup processes, or mixing chlorine streams to meet this threshold, followed by a catalytic reaction with carbon monoxide over an activated carbon catalyst in a shell and tube reactor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chlorine feed stream with high chlorine oxide content is used, then phosgene production can proceed, but activated carbon catalyst deactivates rapidly
Solution Approach 1:
The patent applies preliminary action by removing chlorine oxides from the chlorine feed stream before the catalytic reaction. This is achieved through pre-treatment steps such as washing with water or other liquids, or passing through absorption columns, which eliminate the harmful chlorine oxide component prior to it reaching the activated carbon catalyst, thereby preventing catalyst deactivation while maintaining phosgene production capability.
2Duration of action of stationary object
If chlorine oxide content in feed stream is reduced to below 130 ppm, then catalyst service life is extended, but additional purification steps are required
Solution Approach 1:
The patent applies the extraction principle by removing chlorine oxides from the chlorine feed stream through specific purification steps. The chlorine stream is treated with water or other liquids to extract and remove chlorine oxides, or passed through absorption columns that selectively extract chlorine oxides from the gas stream, thereby reducing the chlorine oxide content to below 130 ppm and extending catalyst service life.
Solution Approach 2:
The patent uses water or other liquids as intermediary substances to remove chlorine oxides from the chlorine feed stream. These intermediaries facilitate the removal process by absorbing or reacting with chlorine oxides, making the purification step more effective and enabling extended catalyst operation without requiring overly complex purification systems.
3Reliability
If chlorine feed stream is treated to remove chlorine oxides, then catalyst deactivation is prevented, but production downtime may increase due to treatment requirements
Solution Approach 1:
The patent applies continuity of useful action by implementing chlorine oxide removal steps that can be performed continuously or in a manner that minimizes interruption to phosgene production. The purification processes are designed to maintain continuous operation or require minimal downtime, ensuring that catalyst stability is improved without significant loss of production time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Extends the service life of the activated carbon catalyst, reducing catalyst deactivation and minimizing production downtime, while maintaining phosgene quality.
Implementation Method 1
the catalytic reaction of carbon monoxide with chlorine over an activated carbon catalyst
Implementation Method 2
On account of the strong exothermicity of the reaction, primarily shell and tube reactors with activated carbon catalysts present therein are used
Data Source
AI summary
The present invention relates to a process for preparing phosgene by reacting chlorine with carbon monoxide over an activated carbon catalyst, wherein the content of chlorine oxides in the chlorine feed stream is low, to an apparatus for preparation of phosgene and to the use of the phosgene prepared by the process of the invention.