Understanding Separation Mechanisms and Recovery of Nitrous Oxide (N 2 O) from Nitric Acid Plant Tail Gases Using Computational Molecular Modeling
Year: 2026
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Separation and recovery of nitrous oxide (N 2 O) from nitric acid tail gases is a pressing environmental challenge due to the dual role of N 2 O as a potent greenhouse gas and as the leading ozone-depleting substance. While catalytic destruction is the current industrial practice, it often lacks selectivity and generates secondary emissions, overlooking the added value of recovering N 2 O as a chemical feedstock. In this work, we employ atomistic nonequilibrium Molecular Dynamics (MD) simulations to investigate the selective retention and transport of N 2 O in zeolitic membranes. Three zeolite types all-silica Linde Type A (LTA), all-silica CDO-type zeolite, and calcium-exchanged Linde Type A (Ca-LTA, Si/Al = 1.0) were examined, and our results show that Ca-LTA exhibits superior recovery performance. Simulations were conducted across a wide range of temperatures (300–600 K) and pressures (100–932 atm) for equimolar binary, ternary, and quaternary mixtures, as well as five cases closely matching industrial gas composition (N 2 mole fraction ≈ 0.4–0.8), providing direct insight into realistic operating conditions. Our results demonstrate that Ca-LTA retains N 2 O through strong interactions with Ca 2+, while N 2, NO, and NO 2 permeate more readily. N 2 O permeation was negligible under most conditions, but trace breakthrough appeared in equimolar binary mixtures at 500 K, in ternary and quaternary mixtures at 450 K, and under industrial-like feeds with N 2 mole fraction = 0.8 at 400 K, where only very few molecules of N 2 O permeated. In contrast, NO exhibited the highest mobility, while N 2 and NO 2 showed modest to intermediate permeability, both increasing systematically with temperature. Importantly, our results capture the experimentally observed transport behavior of pure gases in Ca-LTA membranes, and also predict the separation factors (SF), permeability, diffusion coefficients, and adsorption/permeation selectivity. Finally, our results provide the first molecular-level predictions for binary, ternary, quaternary, and industrial-composition mixtures in the absence of experimental data. Together, these findings establish Ca-LTA as a robust recovery medium for N 2 O, maintaining high selectivity across diverse feed compositions, ranging from simple gases to industrial-like mixtures, and aligning with experimental expectations for zeolitic membranes.
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
OpenAlex ID: W7126192928