At Nationwide Boiler, we’ve spent more than four decades helping industries meet demanding emissions requirements with solutions that deliver reliability, performance, and proven results. Our CataStak™ Selective Catalytic Reduction (SCR) System is one of those solutions—engineered to achieve ultra-low, single-digit NOx emissions on package boilers and a wide range of fired equipment. As air-quality regulations continue to tighten, understanding NOx and the importance of emissions control is more critical than ever.
What Is NOx?
NOx, or nitrogen oxides, represents a group of highly reactive gases formed when nitrogen and oxygen combine during high-temperature combustion. These emissions are common in industrial boilers and fired equipment, including:
- Package boilers
- Fired heaters
- Gas turbines
- Heat recovery steam generators
The amount of NOx produced depends on several operational factors:
- Fuel type
- Burner design
- Peak combustion temperature
- System configuration
- Use of emissions-control technology such as an SCR
Why Reducing NOx Emissions Matters
Once released into the atmosphere, NOx contributes to a series of reactions that impact both environmental quality and human health. Even at low concentrations, these gases can significantly affect regional air quality.


