An overview of membrane based NO_x removal technologies and denitrification filters

Air pollution has emerged as a significant global issue, largely due to the increasing demand for energy and industrial processes that release harmful gases into the atmosphere. Among these pollutants, nitrous oxides (NO_x) are particularly concerning. While conventional Nox removal techniques like Selective Catalytic Reduction (SCR), Selective Non-Catalytic Reduction (SNCR), and Non-Selective Catalytic Reduction (NSCR) are effective, they are hindered by high operational costs, catalyst deactivation, ammonia slip, and environmental issues. In contrast, membrane technologies, especially catalytic membranes, offer significant advantages such as low operational costs, high selectivity, and the ability to operate at lower NOx concentrations in environmentally friendly, scalable processes. Membranes like hollow zeolite and activated carbon-based systems have achieved NOx removal efficiencies above 95 %. Moreover, the incorporation of metals into membranes has enhanced their performance by lowering operating temperatures and increasing surface area. A comparative analysis shows that catalytic membranes can achieve similar or better efficiencies than SCR at milder conditions, reducing environmental impact and equipment corrosion. To further improve membrane-based NOx removal, this paper recommends the development of advanced catalysts, further research on multi-component gas systems, and comprehensive techno-economic and environmental assessments. Additionally, pilot-scale studies are needed to evaluate the practical performance and scalability of these technologies for industrial applications.