Modeling and Simulation of a New Proposed System for the Elimination of Nitrogen Contained in Natural Gas.

This work presents the modeling and simulation of a new biotechnological system for nitrogen removal from natural gas, based on immobilized diazotrophic microorganisms operating in a packed-bed bioreactor. The model incorporates a first-order apparent reaction rate and a diffusion-reaction formulation within porous supports, coupled with reactor-scale mass balances and pressure-drop effects. Because system-specific kinetic data for gas-solid diazotrophic systems are not yet available, an apparent first-order rate was adopted as a nominal reference value, and its influence on system behavior was evaluated through sensitivity analysis. The reactor was designed to reduce the nitrogen content of the gas stream to ≤4%, a typical specification for commercial natural-gas processing. Biological feasibility is supported by evidence of nitrogen fixation in methane-rich and strictly anoxic environments, as well as by reports of metabolically active immobilized communities under predominantly gaseous conditions. A comprehensive parametric sensitivity analysis was performed over fabrication-feasible ranges of support properties (surface area, porosity, pore radius, and particle radius). The results identify structural conditions that minimize reactor length and support mass while maintaining feasible pressure drops. A perspective for laboratory-scale experimental validation is also outlined. Overall, the proposed system represents a technically viable and environmentally favorable alternative for reducing nitrogen content in natural gas and mitigating emissions associated with flaring.