Innovations and Sustainability Metrics for Nitric Acid Production: Emission Control and Process Optimization

Nitric acid production is a cornerstone of the chemical industry, yet it presents considerable environmental challenges, primarily due to greenhouse gas emissions such as nitrous oxide (N2O) and nitrogen oxides (NOx). This manuscript critically examines the key performance indicators (KPIs) that define the gate-to-gate environmental sustainability of nitric acid plants. Quantitative metrics and related benchmarks achieved in modern plants, e.g., energy efficiency (ca. 2 GJ exported per ton of HNO3) and NOx/N2O reduction (95–99%), are presented. Strategies to enhance these KPIs are discussed, including process integration, intensification, advanced emission control technologies, and operational optimization. Special attention is given to the chemical conversion processes of NOx and N2O, highlighting their roles in minimizing overall emissions. The review also synthesizes recent literature to showcase emerging trends, regulatory developments, and technological innovations that facilitate the transition toward more sustainable nitric acid production. Finally, the article identifies current research gaps and outlines future directions for the field.