Electrolyzer Off-Gas Combustion
Catalytic off-gas treatment for hydrogen and CO₂ electrolysis systems
As electrolyzer deployments scale globally, the safe and compliant treatment of combustible off-gas is becoming an increasingly important design requirement. Off-gas conditions can vary significantly depending on the electrolyzer technology and operating mode, from transient hydrogen peaks during startup and shutdown to continuous CO streams in CO₂ electrolysis.
These different operating conditions place high demands on the combustion system. It must handle rapid changes in flow, gas composition and energy content while maintaining reliable conversion across a wide operating range, ideally without the need for support fuel.
Transient hydrogen off-gas treatment
During startup and shutdown of an electrolyzer, hydrogen is produced in significant peaks before the system reaches steady-state operation. This gas cannot yet be directed to downstream processes or storage and must be safely handled on-site. The challenge is that these transient streams can vary rapidly in flow, concentration and energy content, placing high demands on the system’s ability to respond immediately across a wide operating window.
Hydrogen has an exceptionally wide flammability range of 4 to 75% in air, which makes variable-concentration streams particularly difficult to manage with conventional flame-based burners. Maintaining stable ignition across rapidly changing concentrations typically requires support fuel, adding system complexity and cost. Catalytic combustion addresses this, enabling complete oxidation of transient hydrogen streams from ultra-lean to energy-rich compositions, without a flame to stabilize and without auxiliary fuel.
Hydrogen emission compliance
In a growing number of markets, venting hydrogen to the atmosphere is not permitted. Regulations already in place in markets such as Taiwan require that hydrogen off-gas be treated before release, and emerging regulatory frameworks governing the indirect greenhouse gas effects of hydrogen emissions are expected to extend these requirements further.
ATEX-approved fans offer a conventional approach for venting hydrogen safely during transient operation, but ventilation alone does not oxidize the gas and provides no solution where atmospheric release is regulated. For electrolyzer operators, compliance requires a combustion solution that functions reliably across the variable flows and concentrations characteristic of real-world operation, not only under ideal steady-state conditions. Catalytic systems provide this reliability, maintaining complete conversion across the full operating range without the flame stability limitations of conventional burners.
Off-gas treatment in CO₂ electrolysis systems
In CO₂ electrolysis systems, carbon monoxide is produced as a product gas for syngas and synthetic fuel applications. Where off-gas streams contain residual or vented CO, safe treatment is critical. Carbon monoxide is both toxic and flammable, and regulatory emission limits require complete oxidation with no unburned residual.
Unlike the transient hydrogen scenarios above, CO off-gas in CO₂ electrolysis systems is more continuous in nature. Stable, long-term performance and consistent conversion efficiency at varying flow rates are the primary requirements. Catalytic systems meet these requirements while operating within the compact footprints typical of electrolyzer installations.
CataLite® Burners for Electrolyzer Off-Gas Combustion
CataLite® Burners from Catator are designed for catalytic combustion of off-gas streams with highly variable and transient concentrations of combustible gases, making them well suited for the full range of electrolyzer off-gas applications. With a turndown ratio of up to 1:50 based on the energy content of the off-gas, the burners handle everything from startup hydrogen peaks to steady-state CO treatment without the need for support fuel.
Based on Catator’s patented multi-stage CataLite® Coating technology, the burners feature a highly porous and active catalytic layer applied directly to metallic substrates. This ensures strong adhesion, efficient heat transfer, and stable combustion performance under the transient and variable conditions characteristic of electrolyzer operation.
CataLite® Burners are trusted by leading electrolyzer developers and system integrators, with applications spanning hydrogen production systems and CO₂ electrolysis systems producing carbon monoxide for synthetic fuel applications. Systems are dimensioned to match applicable emission regulations or customer-specific requirements, and are available in standard configurations for faster delivery and pre-validated performance.