Monochloroacetic Acid Production via Boiling Chlorination and Vacuum Distillation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The industrial production of monochloroacetic acid (MCAA) via direct chlorination of acetic acid with chlorine gas faces challenges including corrosion, complex heat management, and risks associated with reactor cooling systems and agitators, leading to maintenance issues and potential loss of reaction control.
Innovation Solution
Conducting the chlorination process in a flow reactor under boiling conditions at near-atmospheric pressure, where heat is managed through evaporation and condensation, and recovering catalysts via vacuum distillation to eliminate the need for agitators and reactor cooling systems, while maintaining catalyst concentration and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direct chlorination is conducted at increased pressure (3-5 barg) with homogeneous catalyst, then reaction efficiency is improved, but corrosion of apparatus and piping worsens
Solution Approach 1:
The invention changes the pressure parameter from increased pressure (3-5 barg) to atmospheric pressure, and changes the catalyst form from homogeneous to heterogeneous (supported on silica gel or alumina). This resolves the contradiction by maintaining reaction efficiency through the heterogeneous catalyst while eliminating the highly corrosive environment associated with high-pressure homogeneous catalysis.
Solution Approach 2:
The invention replaces the homogeneous catalyst system with a heterogeneous catalyst supported on solid carriers (silica gel or alumina). This substitution eliminates the need for complex pressure control systems and cooling apparatus, reducing mechanical complexity while maintaining catalytic function and reducing corrosion.
2Temperature
If reactor cooling system with jacket and agitator is used, then heat removal is improved, but device complexity and maintenance issues worsen
Solution Approach 1:
The invention extracts and eliminates the complex cooling jacket system and mechanical agitator from the reactor design. Heat removal is achieved passively through the reaction setup itself, simplifying the device while maintaining effective temperature control.
Solution Approach 2:
The reaction system is designed to be self-regulating regarding heat management. The exothermic chlorination reaction's heat is managed through the inherent design of the reaction vessel and catalyst support structure, eliminating the need for external cooling systems and mechanical agitation.
3Temperature
If mechanical agitator is used for heat distribution, then heat distribution is improved, but sealing reliability worsens
Solution Approach 1:
The invention removes the mechanical agitator from the system entirely. Heat distribution is achieved through natural convection and the design of the reaction vessel, eliminating sealing issues associated with mechanical rotating parts in corrosive environments.
Solution Approach 2:
The mechanical agitation system is replaced with a passive heat distribution mechanism relying on natural convection currents and the thermal properties of the catalyst support structure, eliminating the need for seals and moving parts.
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
This approach stabilizes the reaction temperature, reduces corrosion risks, and simplifies heat management, minimizing apparatus damage and maintaining reaction control, achieving efficient production of MCAA with reduced catalyst losses and improved process integrity.
Implementation Method 1
heat is fundamentally taken off to an equal extent from the whole of the volume of the reacting liquid through the evaporation of components of the mixture as a result of its boiling
Implementation Method 2
the gaseous effluents from the chlorination condense in the condenser fed with a refrigerant and return to the chlorination process
Implementation Method 3
the catalyst is recovered from the chlorination with the reaction mixture obtained in stage (a) through distillation under reduced pressure in the vacuum column
Data Source
Figure 1
Figure 2
AI summary
A method of producing monochloroacetic acid (MCAA) has been disclosed encompassing (a) a stage of the direct chlorination of acetic acid with chlorine and (b) a stage of recovery of the catalyst in the form of acid chlorides from the reaction mixture before (c) a hydrodehalogenation stage characterized by the fact that the chlorination process (a) is conducted at the boiling temperature of the mixture under a pressure of 0 - 1.0 barg, in an excess of acetic acid with respect to the dosed chlorine gas, while the heat from the reaction is taken off mainly through the evaporation of volatile components of the mixture, followed by their condensation in the reflux condenser above the reactor and the return to the chlorination reaction, after which the reaction mixture containing monochloroacetic acid, acetic acid, dichloroacetic acid and optionally acid chlorides which are present in the mixture and, optionally, anhydrides of these acids, is feed to the vacuum distillation process (b), which is conducted continuously in the distillation column in a vacuum of 0 to 500 mbar from which volatile components of the mixture, mainly acid chlorides, as well as some acetic acid and some monochloroacetic acid are taken off as distillate and returned to the chlorination process as a result of which the catalyst of the chlorination is almost completely recovered.