Hydrochloric Acid Purification via Catalytic Hydrolysis and Adsorption
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Solution Overview
Problem
Existing methods for purifying hydrochloric acid do not consistently achieve the required purity, particularly in gas streams contaminated with hydrofluoric acid and fluorooxygen compounds like trifluoroacetyl fluoride, which can contaminate the acid solution during adiabatic or isothermal absorption.
Innovation Solution
A process involving successive stages of catalytic hydrolysis, washing with an acid solution, and adsorption on activated carbon, followed by adiabatic or isothermal absorption, using a hydrochloric acid solution to collect a purified hydrochloric acid solution, with optional additional steps involving silica gel for further purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional purification methods (distillation column followed by adiabatic absorption) are used, then the process is simple and cost-effective, but the required HCl purity cannot be achieved due to contamination from hydrofluoric acid and fluorooxygen compounds
Solution Approach 1:
The purification process is divided into distinct functional stages: a washing column for removing fluorooxygen compounds, a hydrolysis unit for converting them to HF, and an adsorption column with activated carbon for final purification. This segmentation allows each unit to target specific contaminants, achieving high HCl purity through coordinated action of specialized subsystems.
Solution Approach 2:
The washing column introduces an intermediate treatment step where fluorooxygen compounds are removed or converted before the main absorption process. This intermediary action prevents these compounds from contaminating the final HCl product, acting as a protective barrier between the crude gas stream and the purification system.
2Manufacturing precision
If multiple purification stages are added to achieve high HCl purity, then contamination is reduced, but the device complexity and operational cost increase
Solution Approach 1:
The hydrolysis unit converts harmful fluorooxygen compounds into hydrofluoric acid through controlled hydrolysis. This transformation turns a difficult-to-remove contaminant into a more manageable substance that can be effectively handled by the subsequent activated carbon adsorption stage, thereby converting a purification challenge into a solvable problem.
Solution Approach 2:
Activated carbon with its highly porous structure is employed in the adsorption column to selectively adsorb HF and other residual contaminants from the HCl gas stream. The vast surface area provided by the porous structure enables efficient removal of trace impurities, achieving high purity levels that would be difficult to obtain with non-porous materials.
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
Effectively separates hydrochloric acid from hydrofluoric acid and fluorooxygen compounds, reducing contamination and achieving high purity of the hydrochloric acid solution, including the removal of trifluoroacetic acid, thereby improving the overall purification efficiency.
Implementation Method 1
the catalytic hydrolysis step is carried out on a bed of activated carbon
Implementation Method 2
a step of adsorption of impurities with activated carbon
Implementation Method 3
an adiabatic or isothermal absorption step of the hydrochloric acid in an aqueous solution
Data Source
Figure 1
AI summary
The invention relates to a process for the treatment of a gas stream containing hydrochloric acid, hydrofluoric acid and fluorinated/oxygenated compounds, in which the gas stream is successively subjected to: -a stage of catalytic hydrolysis; -a stage of washing with an acid solution; -a stage of adsorption of impurities by active charcoal; -a stage of adiabatic or isothermal absorption of the hydrochloric acid in an aqueous solution, making it possible to collect a hydrochloric acid solution.