Emission characteristics and operational stability of an industrial-scale pure-ammonia ceramic kiln under long-term operation

• Long-term industrial-scale pure ammonia combustion in ceramics. • NOₓ reduced >91% via staged combustion and tailored SCR/SNCR. • Identified and mitigated catalyst sulfur-alkali poisoning mechanism. • Produced high-quality tiles meeting national standards without carbon emission. This study presents a long-term (3-month) industrial demonstration of pure ammonia (NH 3 ) as the sole fuel in a 150-meter long and 1.6-meter-wide ceramic roller kiln for continuous tile production. Addressing the urgent need for decarbonizing high-temperature industries, we retrofitted a commercial kiln with a dedicated ammonia supply system (30-ton storage, 1200 kg/h capacity) and 276 staged-combustion burners. Comprehensive operational data confirmed stable combustion across preheating (500-950°C), sintering (1250°C), and cooling zones, with exceptional cross-sectional temperature uniformity (±2°C). NOx emissions were primarily controlled through staged combustion and selective catalytic reduction (SCR), achieving >91% reduction (residual NOx ≤ 52 mg/m 3 @18% O 2 ) with minimal supplemental SNCR reagent demand, resulting in the N 2 O emissions remained below 3.0 ppm. Test on SNCR efficiency improved from 8.8% to 86% using nitrogen-diluted ammonia reagent. Post-operation analysis identified potential synergistic sulfur poisoning (9.95% SO 3 on catalysts) and alkali deposition (0.44% K 2 O on the SCR system, with XRD-confirmed sulfate crystallization (CuSO 4 /MgSO 4 ) on Cu-SSZ-13 catalysts. Ceramic tiles produced exhibited high quality (0.074% water absorption, 56.3 ± 0.5 MPa flexural strength) and excellent microstructure, exceeding Chinese standards (GB/T 4100-2015). Mechanistic analysis is provided for the observations and preliminary techno-economic and environmental analysis on this ammonia fired production line is given. This work validates ammonia’s technical viability for zero-carbon ceramic manufacturing and provides critical insights for future industrial deployment.