Combined Reaction System for NH3 Decomposition and CO2 Methanation Using Hydrogen Permeable Membrane Reactor in 1D Model Analysis.

Abstract

In a previous study, we developed an integrated reaction system combining NH₃ decomposition and CO₂ methanation within a membrane reactor, significantly enhancing reactor performance through efficient H₂ separation. Ru/Ba/γ-Al₂O₃ and Ru/ZrO₂ were employed as catalysts for each reaction. To ensure the accuracy and reliability of our results, they were validated through 1D models using FlexPDE Professional Version 7.21/W64 software. Key parameters such as reactor arrangement, catalyst bed positioning, overall heat transfer coefficient, rate constants, and H₂ permeance were investigated to optimize system efficiency. The study revealed that positioning the NH₃ decomposition on the shell side and CO₂ methanation on the tube side resulted in a better performance. Additionally, shifting the methanation catalyst bed downward by approximately one-eighth (10 mm from 80 mm) achieves the highest CO₂ conversion. A sensitivity analysis identified the rate constant of the NH₃ decomposition catalyst and the H₂ permeance of the membrane as the most influential factors in enhancing CO₂ conversion. This highlights the priority of improving membrane H₂ permeance and catalytic activity for NH₃ decomposition to maximize system efficiency.