A review of the current and prospective technologies for nitrogen removal in LNG production

Global demand for Liquefied Natural Gas (LNG) continues to increase as energy consumption rises and lower carbon energy systems are pursued. However, many natural gas resources contain significant nitrogen (N₂) that must be removed to meet heating value specifications, ensure safe operation, and enable efficient LNG production. While several studies examine individual N₂‑removal technologies, existing reviews often consider them in isolation, with limited benchmarking under LNG‑relevant conditions and little coverage of emerging hybrid or intensified concepts. This review delivers the first comprehensive, criteria‑driven comparison of conventional, hybrid, and emerging N₂‑removal technologies, explicitly benchmarking their technical readiness, energy intensity, and economic trade‑offs for LNG production. Established processes such as cryogenic distillation, membranes, adsorption, and absorption are systematically evaluated using key performance criteria, including achievable N₂ removal, operating conditions, pretreatment demands, hydrocarbon losses, energy use, and indicative costs. Cryogenic distillation remains the most mature and widely deployed technology for large scale LNG applications, as it is currently the only approach capable of reducing nitrogen concentrations to below 1 mol% while simultaneously producing on specification LNG. In contrast, membrane and adsorption technologies offer modular and flexible alternatives but are constrained by limited nitrogen selectivity and methane recovery, while absorption-based processes are hindered by solvent losses and methane recompression requirements, highlighting the need for improved N 2 selective solvents. A technology mapping framework was established to identify the optimal operating “sweet spot” for each technology as a function of feed‑gas N₂ content and processing rate. Recent efforts to overcome limitations of conventional N 2 ‑removal methods have shifted toward hybrid and intensified technologies. Rotating Packed Bed (RPB) systems offer a promising alternative to cryogenic columns through enhanced mass transfer, compact design, and lower energy use, with demonstrated performance in Nitrogen Oxides (NOₓ) and Carbon Dioxide (CO₂) separations. This review examines the readiness, economics, and research gaps of conventional, hybrid, and emerging N₂‑removal technologies to guide future innovation and LNG commercialization.