With more than 600 electrochemical projects planned and implemented worldwide – including over 40 turnkey EPC projects – thyssenkrupp nucera combines unrivaled technology expertise with six decades of project execution experience. From small-scale units to some of the world’s largest Chlor-Alkali plants with capacities of more than 1.000.000mt/year of NaOH, we deliver proven performance at scale. We not only offer you the three market-leading technologies for chlor-alkali electrolysis, we also offer an all-round package as a one-stop-shop supplier. ®

Chlor-Alkali Electrolysis

Technology expertise and EPC competence from your one-stop shop

Feedstocks

NaCl Sodium chloride salt

Alternative feedstock

Salt storage and handling

Sulphate removal

Chlorate decomposition

Brine Treatment

Purification

Filtration

Precipitation and clarification

Saturation

Ultra Pure brine

Anolyte dechlorination

Membrane electrolysis

2 NaCl

2 H₂O

Cl₂

2 NaOH

H₂

Depleted brine

Membrane electrolysis

2 NaCl + 2 H₂O

Cl₂ + 2 NaOH + H₂

Chlorine treatment

Compression

Liquefaction

Storage

Evaporation

Absorption and safety system

HCl synthesis

Products

Hypochlorite*

Dry chlorine

Liquid chlorine

Hydro chlorid acid

Hydrogen

Caustic 32 %**

Caustic 50 %**

Worldwide, we have planned and implemented some 600 electrochemical projects, over 40 of them as turnkey engineering, procurement and construction (EPC) plants.

In all these projects, we have worked side by side with customers and extensively proven our expertise in implementing projects from small facilities to huge chlor-alkali plants with capacities of over 800,000 mt/year of NaOH. From the licensing business through engineering and procurement projects to very complex, turnkey projects we have demonstrated our ability to implement projects on time, to the highest standards of quality, and to our customers’ complete satisfaction.

Added value and complete process chains

thyssenkrupp nucera® can cover the scope of a total chlor alkali plant starting from feedstock preparation up to product treatment. Together with thyssenkrupp Uhde, we can offer integration of chlor-alkali plants with EDC, VCM and PVC plants which can use the chlorine directly for EDC production.

Proven quality

At thyssenkrupp nucera® we offer state-of-the-art products that feature engineering of the highest quality while taking economic, ecological and safety considerations into account. The expertise we have gained in the field of electrochemical plants is also the fruit of long-lasting collaboration with important industrial partners and customers.

Chlor-Alkali Electrolysis

The BiTAC family: Setting standards in low power consumption

The latest BiTAC generation in our portfolio is based on more than two decades of expertise and experience in filter press technology.

First marketed in 1994, the pioneering filter press bipolar ion-exchange membrane process electrolyzer, BiTAC, set a new power consumption benchmark of 2,200kWh/t at 6kA/m2. Such a high current density had also never before been achieved by a zero-gap cell. Moreover, BiTAC minimized damage to the ionexchange membranes, which tend to be more vulnerable in a zero-gap environment. These BiTAC design features have been maintained in each subsequent generation, with each one having the same active area of 3.276m2. The n-BiTAC introduced in 2005 further reduced power consumption to 2,060kWh/t and featured a 0.15mm fine cathode mesh. In 2013 the launch of the nx-BiTAC marked another milestone in energy savings with a consumption of 2,010–2,025kWh/t. It was also the first ever cell to include a fine anode mesh. Within three years of first being marketed, nx-BiTAC had achieved record sales of 20 projects worldwide. Then, in 2019 e-BiTAC v7 started commercial operation, pushing energy consumption to a new record low of 1,960-1,979kWh/t NaOH at 6kA/m2.

e-BiTAC v7 benefits

Fine anode mesh reduces cell voltage (minimized gas stagnation).
Smooth anode surface with no dents thanks to unique spot-welding tip.
Superior separation of gas and liquid.
Single piece of cathode mesh to fill gap losses and maximize active surface.
Elastic MWX springs with a large number of contact points to decrease IR drop and make homogeneous distribution of current density possible.
Superior inner circulation to ensure uniform concentration and brine supply.

The design of the e-BiTAC v7 elements brings the following benefits:

The filter press technology utilized in the BiTAC series has specific advantages

Low sealing force required for gaskets, no bolts needed
Fast remembraning of complete electrolyzer
Smaller maintenance area required
Lower power consumption through joining anode and cathode compartments by explosion bonding

Woven mesh cathode with MWX spring

The entire active area of the cathode side is covered with a high density woven mesh with activated cathode coating. Woven mesh conducts current without dampening the advantageous effect of the cathode spring and anode mesh. A spring conductor – MWX spring – fixed underneath the woven cathode mesh gently pushes the cathode mesh and the ion-exchange membranes against the anode at optimum pressure to protect the ion-exchange membranes from any mechanical damage. The MWX spring is a key feature of today’s zero-gap technology. It is designed to maintain optimum elasticity at all levels of spring compression, which ensures a better operating environment for ion-exchange membranes. At the same time, current conductivity is optimized by creating 30,000 contact points per element, thus contributing to a lower cell voltage.

Fine anode mesh with smooth surface

The semi-fine anode mesh allows smoother gas release from the anode mesh surface and contributes to voltage reduction. A superior current distribution as well as less voltage drop across the metallic structure are the result. The new “no-dent spot welding” technique ensures a completely flat face over the whole anode mesh surface – for uniform contact with the ion-exchange membrane and an extended membrane lifespan.

Downcomer

The downcomer has a special V-shape and utilizes the gas lift effect to create a high degree of internal brine circulation. This ensures an ideal distribution with uniform density and temperature within the anode compartment. The cathode compartment has no downcomer as caustic soda and hydrogen are easily separated and the difference between the inlet and outlet concentrations of the caustic soda are very small.

By electrolyzing an aqueous solution of sodium chloride, the electrolyzer produces gaseous chlorine and sodium hydroxide as well as hydrogen, the principal by-product. Chlorine is produced at the anodes, sodium hydroxide and hydrogen at the cathodes. The overall reaction is as follows:

Chlor-Alkali Electrolysis

The BM 2.7 single-element series

Major energy savings from zero-gap technology

Nearly 30 years after the single-element membrane cell was first marketed, the highly successful BM2.7 series is now available in generation “6plus”. However, cells from every generation are compatible, having identical dimensions that fit in the electrolyzer racks.

Since the introduction of the BM2.7v3 in 1997, the first laser-welded cell with anode-side internals enabling acidified operation, the BM series has continuously set new standards in chlor-alkali electrolysis. This development culminated in the BM2.7v6plus launched in 2019, a full zero-gap cell featuring a flexible elastic element in the proven BM single-element design, reducing power consumption to below 1,980 kWh per metric ton of NaOH at 6 kA/m².

single-element + Elastic element = Zero gap

The defining feature of the BM2.7v6plus is a zero gap over the entire active membrane area. This is achieved by combining a single-element with an elastic element. With the woven mesh cathode design and a state-of-the-art coating, high resistance to reverse pressure and pressure upsets is also ensured. The combination of the single and elastic elements brings key benefits.

Generation 6plus & further development

Since 2012 when the first full zero gap cell with generation 6 was launched, a new high point has been reached as the generation 6plus of the BM family was released offering optimized design features and thus breaking the barrier of 1,980kWh per metric ton of NaOH at 6kA/m2. Highlights are an accessible active area of 2.85m2 and longer membrane life time under high current density operation beyond 6kA/m2. And the next generation is already under development.

The BM 2.7 single-element series

Key benefits of the BM2.7 single-element series

Energy savings: Significantly lower energy consumption through increased membrane utilization and a full zero-gap design.
Enhanced efficiency: More uniform current distribution and improved gas bubble release, minimizing gas stagnation within the cell.
Leak-proof design: Unique single-element design ensuring 100% leak-tight operation.
Independent pressure control: Direct control of pressure on elastic elements and membranes, independent of flange bolt torque.
Extended membrane life: Zero-gap operation across the full active area extends membrane service life.

Every BM2.7 single-element is fully assembled and tested before inserting it into the electrolyzer stack.

Zero gap

Combining an expanded-metal current distributor with a woven mesh cathode and an elastic element enables a “zero gap” over the whole membrane area. The whole membrane area is active, and significant energy savings as well as a longer membrane life are the results.

Cathode (NaOH and H2 production)

Anode (Cl2 production)

Cathode as woven mesh

Elastic element

Current distributor

Shoulder and inner collecting channel

Anode from expanded metal

Ion-exchange membrane

Downcomer

The downcomer has a special V-shape and utilizes the gas lift effect to create a high degree of internal brine circulation. This ensures an ideal distribution of brine with uniform density and temperature within the anode compartment. The cathode compartment has no downcomer as caustic soda and hydrogen are easily separated and the difference between the inlet and outlet concentrations of the caustic soda are very small.

Smooth, safe operation

Brine and chlorine (anode side) as well as caustic soda and hydrogen (cathode side) are continuously transported from feed pipes at the bottom to the upper end of the compartments. This ensures that the membrane works optimally. Gas and liquid are separated completely in the collecting channel, ensuring two homogeneous outlet phases and minimizing internal differential pressure fluctuations. This enhances membrane life even further. For maximum safety, both compartments remain flooded even in stand-by mode so hydrogen and chlorine gases cannot meet.

BM2.7v6 benefits

Unique sealing and hose system, 100 % leakproof up to 4.7 barg (operating pressure: below 0.5 barg)
Roller suspension of each single-element ensures precise adjustment of contact pressure
Hard, long-wearing PTFE gaskets
Assembly and testing of elements in clean area outside cell house
Assembled elements can be stored for many months
Fast and simple replacement of elements with fully pre-tested elements
Only one type of element in one electrolyzer (no special end elements required)

Chlor-Alkali Electrolysis

Oxygen-depolarized cathode: Quantum leap in sustainability

In countries where electricity is expensive, the NaCl-ODC electrolysis technology developed in collaboration with Covestro offers distinct advantages: for example, up to 25% less energy consumption than conventional membrane-based technology.

Hydrogen formation suppressed

NaCl-ODC electrolysis technology is based on oxygen-depolarized cathodes (ODCs) integrated into the single-element electrolysis technology (BM2.7 design). The decisive difference between NaCl-ODC electrolysis and conventional membrane based technology is in the cathode; the anode remains unchanged. The oxygen introduced into the cathode compartment suppresses the formation of hydrogen, which results in a reduction in cell voltage from around 3 V to 2 V. This in turn enables ODC technology to cut power consumption by up to 25%, for example, 1,550 kWH/mt NaOH at 6 kA/m2. Alternatively, the same power input can be used to achieve a corresponding increase in production capacity. By saving energy, ODC technology indirectly helps customers to improve their carbon foot print and enhance their sustainability.

Easy upgrades, fully compatible

What’s more, a plant running on conventional membrane technology can be partly or entirely converted to NaCl-ODC technology, if required. Since the electrolysis cells and brine cycle are fully compatible, NaCl-ODC and conventional membrane technologies can be easily combined in a single plant.

The ODC process

The ODC structure itself consists of a current distributor (woven metal mesh), a catalyst and a binder. The current distributor acts as a support structure for the catalyst and the binder. The reaction proceeds in several steps: It starts with permeation of oxygen into the porous ODC structure followed by a second step, in which oxygen dissolves in the caustic electrolyte and diffuses to the catalyst surface. Oxygen is then chemically reduced and the reaction products are removed by convective transport.

Characteristic for the process is the 3-phase boundary of liquid, gas and the solid catalyst surface where the reaction occurs. This is essential to bring oxygen, caustic and catalyst in contact for the reaction and it sets our cell design apart from other technologies.

ODC benefits

Up to 25% less energy consumption than conventional membrane based technology
Ecologically valuable solution thanks to lower CO2 emissions
BM2.7 and ODC technologies combinable in a single plant thanks to full compatibility of electrolysis cells and brine cycle
Reliable, well-proven technology
Higher degree of site flexibility with regard to electricity and hydrogen supplies

Several innovations in our contract-execution concepts are specifically designed to make cost-effective, space-saving chlorine production possible.

Compact cell-house design

Our standardized compact cell-house design minimizes investment costs, reduces space requirements, and simplifies maintenance. Its space-saving layout optimizes equipment placement, reducing steel structures and using the area beneath electrolyzers for tanks, pumps, and heat exchangers. The design features no pits and includes an integrated catholyte system.

Skid-mounted technology

To meet growing demand for small-capacity chlorine plants, we offer skid-mounted solutions based on our proven process expertise. Available in capacities of 5,000 or 15,000 mt/year Cl₂, these standardized, pre-assembled modules fit into standard containers for easy transport. Solutions include brine filtration and purification, NaCl electrolysis, Chlorine cooling and chilling, Chlorine Drying, Waste gas dechlorination and sodium hypochlorite production. Individual skids can also be added to existing plants for modernization or debottlenecking.

Benefits of skid-mounted plants

Standardized engineering for optimized costs
Process simplification to reduce costs
Fewer civil and erection works on site
Lower capital expenditure risks
Much faster project schedule than conventional plants

Chlor-Alkali Electrolysis

Worldwide service - everything from a single source

Our ongoing aim is to enter into long-term partnerships with our customers. Therefore, our world-leading technologies and solutions for high-efficiency electrolysis plants are rounded off by a comprehensive service portfolio to meet all your operational needs – wherever in the world your plant may be located.

Digital plant monitoring and optimization

nucera evaluator

The nucera evaluator measures single-element voltages and operating parameters 125 times per second with 3 mV accuracy. It analyzes equipment condition and predicts future performance, enabling safer operation, targeted maintenance, clear reporting, and faster troubleshooting.

Remote condition monitoring

Remote condition monitoring collects plant data from systems such as the nucera evaluator and nucera administrator and sends it to our Technology Service Center for analysis. Our specialists use this data to optimize performance, improve reliability, and enable targeted preventive maintenance, increasing overall plant availability.

Chlor-Alkali Electrolysis

Long-term partnership

Full service - maximum service, minimal downtime

Our full-service maintenance minimizes electrolyzer downtime and ensures high-quality work through a single point of responsibility, extensive expertise, and highly qualified service technicians.

Long-term partnership

As your long-term partner, we help maximize efficiency, safety, plant availability, and product quality throughout the plant lifecycle. Our modular service portfolio supports reduced power consumption and best-in-class operational performance.

Spare parts

Our electrolyzers are designed for minimal maintenance. When replacements are needed, certified and thoroughly tested spare parts ensure reliable, efficient operation, while proven supply chains help minimize delivery times.

Upgrades & retrofits

Our upgrade and retrofit solutions improve plant performance and reduce energy consumption per metric ton of NaOH. They can be implemented across an entire cell room or on individual electrolyzers, while maximizing the use of existing equipment.

Customer

thyssenkrupp nucera

Element Manufacturer
Membrane Supplier
Logistics Partner
Coating Supplier
Assembly Partner
Spare Parts Supplier
Leasing of Elements

Asset Managment
Spare Parts Supply & Management
Revamps
Service Center & Fields Services

Chlor-Alkali Electrolysis

Contact

We shape the new era. Contact If you are interested in our green hydrogen and chlor-alkali solutions, or would like more information about our services, please contact us via our contact form. Copyright 2026 thyssenkrupp nucera | Imprint | Legal Notes | Data Protection | Compliance | Global P rocurement ©

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