(477h) Life Cycle Assessment of Methane Pyrolysis through a 3-Stage Catalytic Membrane System

A new methane catalytic pyrolysis system was proposed using a 3-stage catalytic membrane system to produce hydrogen and carbon nanotubes (CNTs) from natural gas. In the designed process, the methane catalytic decomposition was conducted at a temperature of 550 °C using a nickel catalyst, which is significantly lower than the steam reforming temperature range of 700 to 1000 °C. Moreover, pressure swing adsorption (PSA) is avoided by applying a membrane to separate the hydrogen from the flue gas. The produced CNTs can act as carbon materials, such as activated carbon. Based on this, a series of studies were conducted to investigate the environmental friendliness of the proposed system. Aspen Plus V14 was first used to simulate the proposed system, and the results were used to conduct a cradle-to-grave life cycle assessment (LCA) to compare the environmental impacts of the 3-stage catalytic membrane system and the commercial steam reforming process. The LCA was conducted using SimaPro 9.5 with the ReCiPe 2016 Midpoint (H) method. The results showed that the global warming potential of producing 1 kg of hydrogen through the 3-stage catalytic membrane system and steam reforming in Singapore was 9.46 and 11.7 kg CO2-eq, respectively. Based on the results, it is of interest to further optimize the process experimentally and build a demonstration plant to investigate the feasibility of the proposed system.