Key Benefits

  • Meet strict environmental standards
  • Low OPEX and CAPEX
  • Easy integration

Beat your toughest emissions challenges – and reduce costs

Control gaseous emissions and dust in a single step solution

CataFlex® is a patent-pending filter bag built with embedded catalyst, specifically designed to treat off-gasses in high-dust factory environments.

This breakthrough in filter bag design is the result of a partnership between FLSmidth’s Airtech fabric filters and Haldor Topsøe, a world leader in catalysis and surface science. Not only have we succeeded in merging two advanced technologies into one – we have also gained the know-how to ensure complete control through all stages of development. Because the AFT® filter bags are manufactured by FLSmidth, and the catalyst is produced in partnership, quality control and continuous technological improvements are carried out fully in-house.

Cataflex® catalytic filter in 3D
We have always invested considerably in developing and implementing new, innovative technology to improve productivity and reduce environmental impact. At the cement industry’s largest research centre, FLSmidth R&D Centre Dania in Denmark, new technology is constantly developed and refined through computational fluid dynamics (CFD) and validated through field research and R&D pilot-scale modelling. It’s just what you can expect from an industry leader in catalytic solutions.

How Does the CataFlex Work?

A CataFlex bag consists of up to three layers of woven fiberglass. Each layer can feature its own unique catalytic formula, enabling the bag to remove multiple gaseous compounds and dust in a one-step process. This eliminates the need for costly and space demanding tail-end gas removal equipment, and ensures future compliance.


Highly effective and customisable for demanding industrial operations, CataFlex solutions are based on a universal design with a unique catalytic formula. Using selective catalytic reduction (SCR) technology to remove NOx, NH₃, dioxins/furans, and a wide range of volatile organic compounds (VOCs), the CataFlex will help your factory adhere to the most stringent environmental standards.


With its ePTFE membrane, the CataFlex removes dust prior to the catalytic reaction at the highest possible rates. By removing contact between the catalyst and potentially harmful particles, CataFlex catalytic filter bags provide exceptional resistance to catalyst poisoning.




Air pollution control using the best of ceramic cleaning technology.

The CataMax catalytic solution is constructed similarly to a traditional bag filter, but with porous ceramic elements. This enables it to remove NOx, NH₃, dioxins/furans and a wide range of volatile organic compounds (VOCs) from the flue gas in a single step.


Gas distribution in the filter is optimised to reduce the velocity profiles near the ceramic elements. This extends the lifetime of these elements and allows for a more compact design and trouble-free operation.


The filter can be easily maintained while online using the SmartPulse Controller®, a new-generation controller that uses microprocessor technology to optimise the control of bag filters. First, dust from the gas stream is captured on the surface of the ceramic elements by pulsed, pressurised air. Then inside the filter, the harmful gases are trapped and removed in the matrix of the ceramics through a specially designed catalyst that converts and removes volatile organic compounds (VOCs), dioxins, NOx and NH3 emissions. The initial removal of dust prevents it from deactivating the embedded catalyst.


Clear the air with CataFlex and CataMax catalytic filters

Meet strict environmental standards 

The CataFlex helps the industry achieve compliance with the latest regulations, including the US NESHAP regulations, in which restricting o-HAPS (organic hazardous air pollutants) is vital. 



Extremely effective in a high temperature range, CataFlex provides the most durable catalytic filtration solution available. However, by using separately thermal oxidizers, SCR, and filtration technologies, CataFlex also delivers unique cost-saving benefits, offering significantly lower CAPEX and OPEX while still meeting the strictest regulations.

Easy integration

A CataFlex catalytic filter bag can be easily integrated into existing operations, typically in one of three ways:


  • New installation
  • Conversion from ESP
  • Upgrading existing fabric filters


Due to its design similarities to conventional filter bags, the CataFlex can in many cases be easily installed in an existing filter. This eliminates the need to invest in new or upgraded ID fans, compressors, or other auxiliaries when upgrading your existing fabric filter to a catalytic fabric filter. 


Catalytic filter for efficient removal of hazardous pollutants 

Optimal catalyst performance

Our catalytic filtration solutions offer a range of other important advantages that improve their effectiveness. This includes optimised conditions for chemical reaction, thanks to a design enabling cross-flow instead of by-flow. This allows the contaminated air – after dust has been removed – to be forced into deep contact with the catalyst reagents.

Our catalytic filtration solutions turn your ordinary bag filters into a powerful dust filtration and gaseous emissions control system. The highly effective filters remove all harmful pollutants, in accordance with the demands of local authorities around the world.

Dust, NOx, NH₃ 

The filtration process starts with the removal of dust. Not only does it comply with the highest emission standards – it also protects the catalyst from dust, just as in a low-dust catalytic environment.

Selective catalytic reduction (SCR) in the catalytic bags makes use of ammonia to remove NOx from the off-gas, converting it into harmless nitrogen and water.

At the same time, NH₃ emission levels are minimised using highly effective ammonia slip control technology.

Hazardous air pollutants, VOC

The catalyst technology oxidises a wide range of volatile organic compounds (VOC) into carbon dioxide and water. This includes all seven species defined by the US National Emissions Standards for Hazardous Air Pollutants (NESHAP), including cyclic, aliphatic and aromatic hydrocarbons. 

Dioxins and furans

These harmful substances are easily removed and transformed into harmless compounds. For some applications, CO can also be removed in the same temperature range as the other catalytic reactions with some integrations.

CataFlex® catalytic filter bags
CataMax™ catalytic solution 
Woven glass bags (1 or more layers)   Rigid ceramic element
Few mm thickness, medium to high catalyst load  2 cm thickness, high catalyst load
ΔP as standard fabric filters   ΔP higher than standard fabric filters
200 - 260°C temperature window   200 - 400°C temperature window
Possible sensitivity to high SO₂ concentration 
within the operational temperature range
 Low or no sensitivity to SO₂ in the 
 higher temperatures range

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