Industrial Deep Tech · Refinery Decarbonisation · TRL 4–5

Redox-Mediated
H₂S Splitting
Proprietary Sulfur Separation · Green H₂ · Zero SO₂

Every refinery burns its hydrogen sulfide in a Claus unit — destroying the embedded hydrogen and emitting SO₂. ElementalS replaces this century-old combustion process with a redox-mediated catalytic platform that recovers green hydrogen and high-purity elemental sulfur from the same acid gas stream. No combustion. No SO₂. No CO₂.

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~80%
Less electricity
vs. PEM water electrolysis
Zero
SO₂ emissions —
no combustion step
TRL 4–5
Sulfur separation validated
Full TEA completed
The Problem

Refineries burn the hydrogen they should be recovering

The Claus process — standard in every refinery worldwide — combusts H₂S to recover sulfur. In doing so, it destroys embedded hydrogen, emits SO₂, and forces the same refinery to purchase SMR hydrogen at significant cost and carbon penalty. This is a structural inefficiency hiding in plain sight.

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Claus Process — A Century of Wasted Hydrogen H₂S is combusted as fuel. The hydrogen inside is destroyed, SO₂ is emitted, and tail gas must be incinerated. The gold standard — but one that destroys value on every barrel processed.
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Liquid Redox Systems — Zero SO₂, Zero Value Creation Technologies like LO-CAT, SulFerox, and Unisulf eliminate SO₂ without combustion — but they still destroy the hydrogen and produce low-quality sulfur that cannot be sold commercially.
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Water Electrolysis — Wrong Feedstock, High Cost Green H₂ from water requires ~50–55 kWh/kg and ignores the H₂S stream entirely. Claus keeps running. SO₂ keeps flowing. Two separate cost centres where one should replace both.
ElementalS — Process Architecture
INPUT — H₂S Acid Gas Stream + Renewable Electricity
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Redox-Mediated Oxidation ReactorH₂S → Elemental Sulfur + Reduced Mediator
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Proprietary Sulfur Separation Unit
↓
Electrochemical Mediator Regeneration← electricity input here only
Heterogeneous Catalyst HER ReactorH₂ evolves off-field, no CO₂
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🟡 Saleable SulfurHigh-purity product
🟢 Green HydrogenRefinery H₂ network
No combustion · No SO₂ · No CO₂ · Closed-loop mediator
Technology

A Three-Stage Platform Built Around Proprietary Sulfur Separation

ElementalS decouples H₂S oxidation, sulfur recovery, and hydrogen evolution into three distinct, optimised unit operations. H₂S oxidation chemistry is established in literature. The breakthrough is a proprietary sulfur separation system that solves the electrode fouling problem — enabling continuous industrial operation where competing systems cannot.

01
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H₂S Oxidation & Proprietary Sulfur Separation
H₂S contacts an oxidising redox mediator — chemistry established in peer-reviewed literature — producing elemental sulfur and a reduced mediator. Sulfur is continuously removed from the system through a proprietary separation architecture — eliminating the electrode fouling failure mode that prevents competing H₂S electrolysis systems from operating continuously. Bench-validated by the founder: elemental sulfur confirmed, separation demonstrated. The reduced mediator exits to the electrochemical stack.
02
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Electrochemical Mediator Regeneration
The two spent mediators — anodic and cathodic — are simultaneously regenerated in a redox flow electrochemical cell powered by renewable electricity. Because H₂S oxidation is thermodynamically far easier than water splitting, the cell operates at significantly lower voltage — targeting ~10–15 kWh/kg H₂ at system level versus ~53 kWh/kg for commercial PEM water electrolysis: approximately 80% less electricity. All electricity input is confined to this step only.
03
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Catalytic H₂ Evolution — Off-Field
The cathodically regenerated mediator flows over a fixed-bed heterogeneous catalyst reactor where hydrogen evolves entirely off-field — driven by catalysis, not electrochemical potential. No electricity required here. ElementalS is actively developing low-PGM and non-PGM heterogeneous catalysts for this step — eliminating platinum-group metal dependency, reducing system cost, and building proprietary IP advantage over the published system architecture.
Technology Comparison — Industrial H₂S Management Pathways
Technology H₂ Recovery Saleable Sulfur SO₂ Emissions CO₂ Reduction Feedstock Cost
Claus Process
Standard SRU		 None — H₂ destroyed Yes High — combustion None Waste stream
Liquid Redox SRU
Unisulf, LO-CAT, SulFerox, Sulfolin, Hiperion		 None — H₂ not recovered Low quality — unsaleable Zero — no combustion None — SMR unchanged Waste stream
Claus + Green H₂
Claus SRU + PEM Water Electrolysis		 No recovery — H₂ from water, not H₂S Yes (Claus) High — Claus still runs Partial — SMR displaced Pure water + high electricity
SMR + CCS + Claus
Conventional refinery baseline		 No — H₂ from methane, not H₂S Yes (Claus) High — Claus combustion Reduced — CCS partial Natural gas + CCS cost
ElementalS
Redox-Mediated Catalytic H₂S Splitting		 Yes — catalytic H₂ evolution Yes — proprietary separation Zero — no combustion Yes — SMR displaced Waste stream + low energy
The conventional baseline (SMR + CCS + Claus) produces hydrogen from methane while Claus continues destroying the embedded hydrogen in acid gas. Liquid redox systems eliminate SO₂ but recover no hydrogen and produce low-quality unsaleable sulfur. ElementalS is among the first platforms combining zero SO₂, catalytic green H₂ recovery from H₂S, and high-purity saleable sulfur from a single acid gas feed — enabled by a proprietary sulfur separation system that liquid redox competitors cannot match.
Roadmap

Scale Path to Industrial Deployment

From validated bench science to licensed refinery technology — a 3–5 year pathway built for industrial partner collaboration.

2025 — 2026
Catalyst Development & System Validation
Heterogeneous catalyst optimisation for H₂ evolution rate and long-term stability. Redox mediator selection and cycling durability testing. Proprietary sulfur separation architecture development. Full techno-economic assessment and reactor modelling completed.
2026 — 2027
5–25 kW Integrated Pilot Skid
Continuous-operation pilot unit integrating all three stages. System-level energy efficiency validation targeting ~32 kWh/kg H₂ near-term baseline, with roadmap toward 10–15 kWh/kg. Sulfur product quality certification for industrial commodity markets. Catalyst turnover frequency and deactivation characterisation.
2027 — 2028
Refinery Pilot — Modular SRU Replacement
Integration into a live refinery acid gas stream in partnership with industrial EPC and refinery operators. Drop-in SRU replacement demonstrated at operational scale. Hydrogen quality validation for direct injection into refinery H₂ network.
2029 — 2030
Technology Licensing & Commercial Deployment
Licensing model for global refinery operators. Catalyst manufacturing scale-up. Long-term optimisation pathway toward <15 kWh/kg H₂ through advanced catalyst formulation and reactor integration improvements.
Contact

Let's talk refinery decarbonisation

Whether you are a refinery operator, EPC engineering partner, accelerator programme, or investor — we would be glad to hear from you.

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