Polyarylene Sulfide Scrubbing Recycles Hydrogen Sulfide
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Solution Overview
Problem
The formation of polyarylene sulfides is hindered by significant sulfur loss during the complex formation step, leading to undesirable side reactions, variations in molecular weight and mechanical properties, and toxicity issues due to hydrogen sulfide by-products in the waste stream.
Innovation Solution
A method involving the reaction of an organic amide solvent with an alkali metal sulfide in the presence of water to form a complex, followed by scrubbing the hydrogen sulfide by-product with a mixture of organic amide solvent and alkali metal hydroxide to capture and recycle it, thereby reducing sulfur loss and improving process efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If water is present during complex formation, then the reaction proceeds, but sulfur loss increases and hydrogen sulfide toxicity occurs
Solution Approach 1:
The patent converts the harmful hydrogen sulfide byproduct into a beneficial recycled reactant. The scrubbing system captures H2S from the waste stream and converts it back to alkali metal sulfide, which is then fed back into the reactor. This transforms the harmful gas into a valuable resource, eliminating sulfur loss while maintaining reaction productivity.
Solution Approach 2:
The patent implements a feedback loop where the waste stream containing hydrogen sulfide is continuously monitored and fed back into the reaction system after scrubbing treatment. The recycled sulfur-containing stream is combined with fresh reactants and returned to the reactor, creating a closed-loop system that maintains sulfur balance and prevents loss.
2Quantity of substance
If sulfur input is increased to compensate for loss, then polymerization can proceed, but waste stream toxicity increases
Solution Approach 1:
The scrubbing system captures toxic hydrogen sulfide from the waste stream and converts it back into useful alkali metal sulfide. This transformation turns the harmful waste gas into a valuable reactant that can be recycled, eliminating the need to increase sulfur input while preventing waste stream toxicity.
Solution Approach 2:
The patent recovers sulfur from the waste stream through the scrubbing system instead of discarding it. The H2S captured in the scrubber is converted back to sulfide and fed back into the reactor, creating a recovery loop that prevents both sulfur loss and waste stream contamination.
3Productivity
If sulfur loss is not prevented, then process continues, but product quality deteriorates
Solution Approach 1:
The feedback loop ensures that sulfur is continuously recovered and returned to the reaction system, maintaining consistent sulfur levels throughout the process. This prevents the quality deterioration that would result from sulfur loss while allowing continuous operation without interruption.
Solution Approach 2:
By converting the harmful hydrogen sulfide waste into a beneficial recycled reactant, the system maintains consistent sulfur availability for polymerization. This ensures stable product quality with consistent molecular weight and mechanical properties while maintaining continuous productivity.
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 effectively recovers and recycles hydrogen sulfide, reducing sulfur loss to less than 1% and enhancing the consistency of the polyarylene sulfide formation process while minimizing environmental and health hazards.
Implementation Method 1
scrubbing the stream with a scrubbing mixture to capture the hydrogen sulfide
Implementation Method 2
reacting an organic amide solvent with an alkali metal sulfide in the presence of water to form a complex
Data Source
AI summary
A method and system for formation of a polyarylene sulfide is described. The method includes a first stage in which a complex is formed in a reactor. The complex includes the hydrolysis product of an organic amide solvent and an alkali metal hydrosulfide. The complex formation reaction also forms hydrogen sulfide as a by-product. The method also includes treating a fluid stream that is pulled off of the reactor. The treatment includes scrubbing the fluid stream to recover hydrogen sulfide from the stream and return the hydrogen sulfide to the reactor. The recovery and recycle of the hydrogen sulfide can prevent loss of sulfur from a polyarylene sulfide formation process.