Aqueous Mercaptan Extraction for Low-CS2 Sulfide Streams
Solution Overview
Problem
Existing methods are inefficient in removing carbon disulfide impurities from sulfide product streams, particularly in large-scale industrial applications, as they require impractical conditions and fail to achieve low ppmw levels necessary for industrial use.
Innovation Solution
A process involving contacting the product stream with an aqueous solution of a mercaptan and a base to form a mixture, followed by separating an aqueous layer to purify the sulfide stream, and optionally drying it to achieve low CS2 concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to remove carbon disulfide from sulfide product streams, then the process can be implemented, but the removal efficiency is insufficient and cannot achieve low ppmw levels
Solution Approach 1:
The patent introduces an intermediary substance (mercaptan) that mediates the removal of carbon disulfide from the sulfide product stream. The mercaptan reacts with carbon disulfide to form a soluble complex that can be separated from the sulfide product, enabling efficient removal while maintaining high purity levels.
Solution Approach 2:
The patent changes the chemical parameters of the system by introducing a base to deprotonate the mercaptan, creating a thiolate anion that enhances the reaction with carbon disulfide. This parameter change (pH adjustment) significantly improves the removal efficiency and achieves the desired low ppmw levels.
2Manufacturing precision
If harsh conditions are applied to remove impurities, then higher purity can be achieved, but the process becomes commercially impractical for large-scale production
Solution Approach 1:
The mercaptan acts as a selective intermediary that reacts specifically with carbon disulfide under mild conditions. This allows high purity to be achieved without requiring harsh temperatures, pressures, or extreme chemical conditions, making the process commercially feasible for large-scale production.
Solution Approach 2:
The patent optimizes the parameters (concentration of mercaptan, pH level, contact time) to achieve effective impurity removal under mild conditions. By adjusting these parameters, the process achieves high purity while maintaining commercial feasibility and avoiding the need for expensive, complex equipment.
3Manufacturing precision
If extensive purification steps are implemented, then lower CS2 concentrations can be achieved, but the process complexity and time increase
Solution Approach 1:
The patent segments the purification process into two distinct steps: (1) reaction of carbon disulfide with mercaptan to form a soluble complex, and (2) separation of the sulfide product from the aqueous layer. This segmentation simplifies the overall process while achieving the desired low CS2 concentrations without requiring multiple complex purification steps.
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
The process achieves a 100-fold reduction in CS2 concentration, producing a purified sulfide stream with CS2 levels below 100 ppmw, suitable for industrial applications.
Implementation Method 1
contacting the product stream with an aqueous solution of a mercaptan and a base to form a mixture, and removing at least a portion of an aqueous layer from the mixture
Implementation Method 2
contacting the product stream with an aqueous solution of a mercaptan and a base
Data Source
AI summary
Processes for removing carbon disulfide from product streams containing a sulfide compound are performed by contacting the product stream with an aqueous solution comprising a mercaptide to form a mixture, or by contacting the product stream with an aqueous solution comprising a mercaptan and a base to form a mixture. An aqueous layer is removed from the mixture, resulting in a high purity sulfide stream with significantly less carbon disulfide.