H2S Decomposition via Two-Phase Electrochemical Cell
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Solution Overview
Problem
Existing methods for decomposing hydrogen sulfide (H2S) into hydrogen gas and elementary sulfur, such as the Claus process, suffer from energy wastage, environmental hazards, and issues like sulfur storage, catalyst surface poisoning, and gummy sulfur formation, especially in acidic or basic media.
Innovation Solution
A system and method involving an aqueous acidic phase with a pH below 4, an organic phase immiscible with water, and a photo-/electrochemical cell, where H2S is oxidized at an interface between the two phases, allowing elementary sulfur to dissolve in the organic phase and be crystallized, and H+ ions are reduced to hydrogen gas, avoiding mixing and subsequent storage issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the Claus process is used to decompose H2S into sulfur and water, then H2S is almost completely decomposed, but energy stored in H2S is partially wasted and environmentally hazardous gases (SO2 and CO2) are emitted
Solution Approach 1:
The invention extracts the harmful oxidation step that produces SO2 and CO2 from the decomposition process. By using a two-phase system where H2S is decomposed into sulfur and hydrogen without complete oxidation, the harmful gas emissions are eliminated while maintaining high decomposition efficiency.
Solution Approach 2:
The invention changes the chemical parameters of the decomposition process by controlling the oxidation state. Instead of complete oxidation to SO2, the process is modified to produce elementary sulfur in a two-phase system, fundamentally changing the reaction pathway to eliminate harmful emissions.
2Productivity
If photo-/electrochemical methods are performed in acidic medium, then H2S decomposition can proceed, but solubility of H2S gas is very low causing sulfur storage, catalyst surface poisoning, and gummy sulfur formation
Solution Approach 1:
The invention introduces a two-phase system with an organic phase as an intermediary medium. This organic phase mediates between the acidic aqueous phase and the H2S gas, providing a suitable environment for decomposition while preventing the formation of gummy sulfur and catalyst poisoning by controlling sulfur precipitation.
Solution Approach 2:
The invention utilizes phase transitions by implementing a two-phase system where sulfur precipitates from the aqueous phase into the organic phase. This phase transition mechanism prevents sulfur storage issues and maintains operational stability by continuously removing sulfur from the reaction medium.
3Productivity
If photo-/electrochemical methods are conducted in basic medium, then H2S ionization occurs, but stability problems of elementary sulfur arise
Solution Approach 1:
The invention changes the pH parameter control strategy by maintaining acidic conditions (pH below 4) rather than basic conditions. This parameter change ensures both H2S ionization for decomposition and stability of elementary sulfur, avoiding the instability problems that occur in basic media.
Solution Approach 2:
The two-phase system with organic phase acts as an intermediary that stabilizes elementary sulfur. The organic phase provides a stable environment for sulfur precipitation, preventing the stability issues that would otherwise occur in basic aqueous media.
4Productivity
If acidic phase is used for H2S decomposition, then H2S ionization is achieved, but sulfur storage and catalyst surface poisoning occur
Solution Approach 1:
The organic phase serves as an intermediary that resolves the contradiction between acidic conditions and sulfur storage problems. It provides a separate phase for sulfur precipitation, preventing sulfur accumulation in the aqueous phase and eliminating catalyst poisoning while maintaining efficient H2S ionization.
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 enables long-lasting, low-cost, and efficient decomposition of H2S into hydrogen gas and elementary sulfur, preventing sulfur storage and catalyst poisoning, and facilitating smooth removal of elementary sulfur, resulting in uninterrupted and sustainable processes.
Implementation Method 1
an aqueous acidic phase with a pH below 4, providing the ionization of H2S gas in water and comprising at least one redox couple
Implementation Method 2
an oxidation reaction takes place in the interface by which the H2S bubbles carried into the organic phase through the pump are converted into elementary sulfur
Implementation Method 3
an organic phase, which is immiscible in aqueous phase, with a density above the density of water and capable to dissolve elementary sulfur
Implementation Method 4
at least one cooling unit to which the elementary sulfur generated in the column reactor is transferred and is crystallized to be taken out of the system
Implementation Method 5
the oxidation of the redox couple and the reduction reaction of H+
Implementation Method 6
at least one photo-/electrochemical cell comprising at least one first chamber comprising at least one anode electrode, at least one second chamber comprising at least one cathode electrode
Data Source
Figure 1
AI summary
A decomposition system is developed with the present invention for decomposing gaseous hydrogen sulfide (H2S), this system comprising at least one pump (1) supplying H2S gas in the form of bubbles; an aqueous acidic phase (2a) having at least one redox couple which do not mix with each other because of density difference and thus form an interface (2c) where they contact each other; and at least one column reactor (2) comprising an organic phase (2b) with a density above the density of water and capable to dissolve elementary sulfur, wherein an oxidation reaction takes place in the interface (2c) by which the H2S bubbles carried into the organic phase (2b) through the pump (1) are converted into elementary sulfur; at least one cooling unit (3) which provides the crystallization of elementary sulfur to be taken out of the system; at least one photo-/electrochemical cell (5) comprising a first chamber (5A) comprising an anode electrode, a second chamber (5B) coprisingg a cathode electrode, and a membrane (5C) separating the first chamber (5A) from the second chamber (5B), and to which the aqueous acidic phase (2a) in the reactor is transferred and in which the oxidation of the redox couple and the reduction reaction of H+ to H2 take place, wherein following the reduction reaction, the aqueous acidic phase (2a) is transferred back to the column reactor (2); and an energy source (6) generating the required potential difference to be conducted to one of the electrodes for the oxidation of the redox couple and the reduction reaction of H+ to H2.