Adsorption is the answer

Hayley Everett

An innovative smart gas cleaning technology using natural adsorber materials is going mobile.

By definition, adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This surface phenomenon is present in many natural, physical, biological and chemical systems, and is widely used in industrial applications such as heterogeneous catalysts, activated charcoal, capturing and using waste heat to provide cold water for air conditioning and other process requirements, synthetic resins, and water purification, among other purposes.

Austrian gas purification and fermentation specialist Krajete develops adsorber-based purification technologies for emission gases and biological methane production which build on these successful adsorption processes from nature. Based on natural raw materials, the company’s Advanced Adsorption Technology can remove numerous gaseous emissions for waste gas streams, including nitrogen oxide, and reuse them in line with circular economy principles.


Krajete’s physisorption-based Advanced Adsorption Technology has already proven its potential for the almost complete removal of nitrogen oxides from exhaust gases for large cities, car manufacturers, waste disposal firms and mining companies, says Dr. Alexander Krajete, the company’s CEO.

“We specialise in converting problematic emissions as completely as possible into valuable resources through natural processes,” he explains. “To do this, we use a principle known as physisorption – the reversible binding of harmful gas emissions such as nitrogen oxides to natural adsorber materials such as silica, zeolite or aluminium oxide. The advantages of this technology for the circular economy are obvious: all bound pollutants can be removed from the adsorber by simple means, collected, refined, and used commercially.”

While the use of such adsorber materials for gas purification is well known, the reversible binding of the pollutants – and therefore their subsequent use as a valuable material – has not yet been achieved, he adds. In recent years, though, Krajete has achieved this feat in cooperation with several ‘major companies’. In particular, the principle has proved successful in the case of nitrogen oxides; by simply heating the advanced adsorber, the bound nitrogen oxide can be collected and refined into valuable fertiliser by means of simple chemical processes. The adsorber material is then 100% reusable.


Following multiple successful applications of the technology in a variety of industries – such as automotive, waste management and mining – demand for the company’s Advanced Adsorption Technology has grown steadily over the past year. To meet this demand, the technology is now available for the first time in a transportable test unit to allow cost-effective testing of the technology for individual industrial needs directly at the point of emission.

“In order to meet this gratifying interest, we have reacted flexibly and developed a mobile test plant,” says Dr. Krajete. “This can be connected and tested by any interested party directly to its emission stream in the stack. Thus, the potential of our technology can be tested directly and comprehensively without any adaptation of existing processes.”

In this way, the technology’s potential for neat recovery and subsequent commercial use of the captured emissions can be verified, while its potential can also be built upon. For example, the removal of nitrogen oxides is not only important for cleaning up emissions, but also for future CO2 storage technologies. Additionally, other impurities such as carbon monoxide, sulphur dioxide, hydrogen sulphide and hydrocarbons can be captured and utilised with Advanced Adsorption Technology.

“We are further developing the technology into a versatile gas fractionation and recovery system,” adds Dr. Krajete. “Finally creating a commercially attractive alternative to today’s ‘disposable’ processes that collect contaminants but do not allow further utilisation. This is no longer in-keeping with the times.”

The mobile test unit is essentially designed to serve as a bridge-builder between the laboratory, where initial tests prove the suitability of the technology, and the later large-scale plant. The test unit has exactly the same design as the latter, and features a capacity of 400 m3/h.

“Until now, interested parties could either test the technology in the laboratory or not at all – both of which were fraught with risk for subsequent upscaling,” Dr. Krajete says. “With the mobile test facility, we have eliminated this risk. It is a confidence-building measure between us and our prospects and will have a catalytic function for the use of the Advanced Adsorption Technology.

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