Patent of the Month: Solving the “Ammonia Trail” Problem in the Removal of Nitrogen Oxides From Gases

Special Design and Technology Bureau “Catalyst” JSC (Russian Federation) has been granted Eurasian Patent No. 053522 B1 for a dual-action catalyst for industrial gas purification.

The invention is designed to address one of the key environmental problems associated with the removal of nitrogen oxides (NOx) – excess ammonia (NH₃) emissions.

Nitrogen oxides are among the most dangerous air pollutants. They contribute to acid rain, cause respiratory diseases, and play a role in the destruction of the ozone layer. The primary industrial method for removing them is selective catalytic reduction using ammonia. However, this process requires the injection of excess NH₃ (10-15% above the required amount), and this excess inevitably enters the atmosphere.

For a long time, ammonia was considered relatively safe, but modern research has proven otherwise: in the atmosphere, it is re-oxidized to NOx, negating the purification effect and contributing to the formation of toxic aerosols. As a result, environmental regulators in EAEU countries effectively equate the negative impact of NH₃ with that of NOx. Companies find themselves in a difficult situation: they must either under-treat the gases or pay fines and build expensive additional ammonia oxidation units.

The new catalyst solves both problems simultaneously: it reduces NOx and oxidizes residual ammonia in a single reactor.

Key features of the solution:

• a special composition with added manganese, which catalyzes the oxidation of NH₃ into harmless nitrogen and water;
• a bimodal pore structure (small pores for high activity and large pores for rapid gas access), resistant to sulfur and water vapor;
• high mechanical strength (94% abrasion resistance) and a long service life without regeneration.

Tests have shown that at temperatures of 220-360°C, the catalyst achieves NOx conversion rates of 94-99.9% while simultaneously removing 70-97% of residual ammonia.

Thus, this solution eliminates the need for additional purification stages, reduces capital costs, and ensures consistent compliance with environmental standards.