According to the European Environment Agency, 48,000 Europeans died prematurely in 2022 from chronic nitrogen-dioxide exposure—about one every eleven minutes. Numbers like these moved TechNews180 to sit down with an innovator tackling the problem head-on.
Dr. Alexander Krajete is the Austrian chemist behind Krajete GmbH, a cleantech firm that treats exhaust gases as resources. Using mineral adsorbers and microbial reactors, the company removes NOx, SOx and CO₂ from industrial streams and “upcycles” the captured molecules. Public references range from Skydiamond’s carbon-negative diamond plant in the UK to a roadside air-cleaning pilot in Heilbronn, Germany, and corrosion-control units for an Austrian oil-and-gas operator.
In this interview, we ask Dr. Krajete why nitrogen oxides matter, how his Regenerative NOx Removal stacks up against SCR and SNCR, and where the technology is headed.
Q: First, let's clarify—what exactly are NOx gases, and where do they originate?
NOx stands for nitrogen oxides, primarily nitric oxide (NO) and nitrogen dioxide (NO₂). They're produced whenever air is heated to extremely high temperatures, common in engines, industrial kilns, boilers, and gas turbines. This is why major sources typically include road traffic, power plants, and heavy industries.”
In more technical terms, NO forms through the high-temperature reaction known as the thermal or Zeldovich mechanism. Once released, NO oxidizes into NO₂ over time, either within exhaust systems or upon contact with ambient air. Typical untreated emissions range widely: diesel engines emit between 200–1,500 mg/Nm³ NOx, while gas turbines typically produce 300–800 mg/Nm³. Regulations usually focus on NO₂ because of its known direct health impacts, thus limits are typically expressed as total NOx concentrations in NO₂ equivalent.
Q: Why exactly are nitrogen oxides considered so harmful to human health and the environment?
NOx irritates respiratory systems, contributes significantly to smog formation, and damages ecosystems through acid rain. The fact that around 48,000 EU citizens died prematurely due to NOx-related issues in 2022 alone highlights the severity of its impact.
Technically speaking, NO₂ reacts with volatile organic compounds and sunlight, forming ground-level ozone—a major respiratory irritant linked to asthma and other lung conditions. Additionally, when NOx combines with moisture inside exhaust pipes or flue systems, it forms nitric acid. This can rapidly corrode metals like steel, as well as concrete structures. As a result, regulators continuously tighten permissible emission limits, currently around 50 mg NOx/Nm³, with proposed EU regulations pushing this benchmark even lower.
Q: With all that in mind, why should businesses urgently act to reduce NOx emissions?
There are three compelling reasons why businesses need to prioritize NOx reduction: tightening EU regulations imposing fines of up to 3% of turnover, costly hidden maintenance issues caused by nitric acid corrosion, and growing ESG expectations from investors and customers. Addressing NOx emissions proactively protects both company finances and public health.”
To elaborate, recent changes in the EU’s Industrial Emissions Directive, effective from August 2024, dramatically lowered permissible NOx emissions. Companies now face penalties starting at 3% of their annual EU revenue for serious violations and even risk operational shutdowns. National laws add even more financial pressure—for instance, Germany can impose fines up to €10 million for demonstrable financial gain linked to violations. Beyond compliance costs, unchecked NOx emissions mix with water vapor to create nitric acid, silently corroding equipment and causing costly downtime. Additionally, investors and customers now factor NOx performance into ESG assessments, influencing investment decisions and supplier relationships.
Q: What are the primary technologies available to businesses for controlling NOx emissions, and how does your regenerative method differ?
There are traditionally two main methods companies use—SNCR and SCR. SNCR involves injecting ammonia directly into very hot exhaust gases for moderate reduction (around 30–50%). SCR involves passing exhaust gases through a heated catalyst combined with ammonia, achieving over 90% removal. Our regenerative NOx removal provides a newer, more efficient alternative. It captures NOx using mineral filters at regular stack temperatures—no ammonia or chemicals involved—and recovers a concentrated stream that can be sold.”
Technically, SNCR introduces ammonia or urea into flue gases at temperatures between 850–1,100 °C, offering partial reduction but with risks of ammonia leaks. SCR operates at lower temperatures (200–300 °C) using ammonia and catalyst surfaces, achieving better results but increasing maintenance and reagent costs significantly. By contrast, our regenerative adsorption captures NOx on reusable zeolite-based minerals at ambient conditions and subsequently releases a highly concentrated product through moderate heating cycles. This method significantly reduces energy demands, eliminates chemical usage, and produces valuable nitric acid or fertiliser-grade outputs.
Q: Specifically compared with SCR technology, why would a business prefer your regenerative approach?
SCR typically requires heating exhaust gas to around 250 °C, relies on costly precious-metal catalysts, and consumes considerable amounts of ammonia. Our method operates at normal stack temperatures, is dry, chemical-free, and typically saves businesses around €100,000 annually on operating costs for medium-sized installations. We inverse the role of NOx, it becomes a resource for a product while keeping compliance.
Simply put, SCR’s process involves reheating flue gases to activate vanadium-titanium catalysts and continuously injecting ammonia or urea. Catalyst poisoning from dust or sulfur compounds frequently necessitates costly replacements. Our regenerative NOx removal technology is integrated after heat recovery systems, requiring no reheating and completely avoiding ammonia handling. Consequently, ongoing maintenance and operational complexity are substantially reduced while turn NOx emissions into a product.
Q: How about when compared to SNCR—why might businesses choose your regenerative method instead?
SNCR sprays ammonia directly into very hot exhaust gas (850–1,100 °C). Although relatively low-cost upfront, it rarely achieves reductions below 200 ppm and can lead to ammonia leaks. Our regenerative adsorption consistently achieves reductions to below 10 ppm at standard exhaust temperatures. Many plants, therefore, use SNCR for initial bulk reduction and then our technology as the finishing step.”
In other words, SNCR typically functions as an initial broad reduction measure, effective within a limited temperature window but not suitable for strict emission regulations. Our regenerative approach offers a precise and reliable finish, ideal for meeting stringent NOx limits without additional chemicals or complex process controls, making it the preferred technology where tight compliance is essential.
Q: You mentioned turning captured NOx into revenue. Is monetizing NOx emissions really feasible for most businesses?
Absolutely. The rich stream becomes fertiliser-grade acid, so many clients sell it and offset the heater’s power bill. What was pollution turns into a product you can invoice.
Because the mineral lasts for years, running cost is mainly electricity for heating. Add revenue from acid sales and avoided corrosion repairs, and the pay-back is clear—especially as emission taxes tighten.
Q: How does the deployment process look for new customers?
Deployment typically involves three straightforward steps: gas sampling, feasibility analysis, and installing our container-based solution. Most projects progress smoothly from initial sampling to full operational handover within one year.”
To clarify further, we first perform comprehensive gas sampling to understand the emission profile precisely. Next, feasibility studies determine the exact design of the mineral beds and regeneration heaters needed. Finally, the installation involves containerized units delivered and integrated directly on-site. Connection points are minimal—just the exhaust stack and a power line—ensuring minimal disruption to your existing processes.
Finally, how does regenerative NOx removal fit into your broader vision of gas purification?
Regenerative NOx removal is the first step. In a bigger picture, all emission gas components shall be treated in the same way. Adsorption, saturation of the mineral adsorber, followed by completion of the cycle with desorption and product generation. This principle shall be rigidly applied also to SOx, slipping hydrocarbons and also CO2.
Conclusion
Controlling nitrogen oxides isn’t just about meeting stricter EU emission rules or avoiding hefty fines—it's also a strategy that makes clear business sense. With NOx linked directly to thousands of preventable deaths every year and quietly corroding pipelines from within, managing emissions has become both a moral imperative and an economic necessity. Businesses now face the choice: see NOx as an ongoing liability or transform it into an asset.
Regenerative NOx removal technology offers exactly this transformation. By capturing NOx on reusable mineral adsorbers and recovering it as valuable nitric acid, companies can protect their reputation, extend the life of critical infrastructure, and create new revenue streams all at once. Rather than treating emissions as waste, forward-thinking operators are seizing the opportunity to turn compliance into competitive advantage because waste becomes an asset as feedstock.
