Volume 68

Research on Enhancing Conversion Performance of Medium-Temperature Ammonia Decomposition Membrane Reactors Based on Metal Foam Heat Transfer Enhancement Kewei Ma, Qi Xia, Zihan Lin

Abstract

Against the background of global low-carbon energy transition, the storage and transportation of hydrogen remain challenging. Ammonia has become an ideal hydrogen carrier due to its high hydrogen density and easy liquefaction. However, conventional medium-temperature ammonia decomposition reactors suffer from low conversion efficiency, poor heat transfer performance, and thermodynamic equilibrium limitations. To address these issues, this study proposes a novel reactor design that integrates metal foam for heat transfer enhancement and hydrogen-selective permeable membrane to break the thermodynamic equilibrium. Experimental results show that metal foam significantly improves the heat transfer performance of the reactor. The 40 PPI copper foam reduces the maximum radial temperature difference to 61.55 °C and greatly increases the overall heat transfer coefficient. In the temperature range of 450-600 °C, the metal foam-packed membrane reactor exhibits much higher conversion than conventional reactors. It achieves nearly complete conversion at 600 °C, and reaches 65.18% at 500 °C, which is 36.93% and 20.43% higher than that of the traditional packed-bed reactor and single membrane reactor, respectively. After parameter optimization, the conversion is further improved to 82.89%, and the reactor shows better stability under high gas hourly space velocity. This work provides a feasible scheme and experimental support for efficient medium-temperature ammonia decomposition for hydrogen production.

Keywords medium-temperature ammonia decomposition, metal foam, hydrogen-selective permeable membrane, heat transfer enhancement