Pentavalent molybdenum species supported on coal waste derived ZSM-5 enhances the activity and stability of the catalyst for methane dehydroaromatization (MDA) reaction

The modernisation era has brought forth increasing environmental concerns, primarily from the escalating production of coal waste material (CWM) and methane. Our research addresses these challenges by outlining a typical approach to convert CWM into zeolite ZSM-5, achieving an impressive 91% crystallinity. This CWM-derived zeolite then serves as an active support in a catalyst specifically designed for the methane dehydroaromatization (MDA) reaction, demonstrating an efficient pathway for waste utilisation and methane conversion. To enhance catalytic performance, we employed a modified molybdenum precursor (MOP), alongside a temperature-programmed carburisation (TPC) method. The successful incorporation and dispersion of molybdenum into the zeolite was confirmed through BET and HAADF-STEM analysis. The catalyst's high effectiveness is primarily due to the identification of very reactive Mo⁵⁺ species, which are responsible for better catalytic activity during methane activation. The density functional theory (DFT) calculations support the role of Mo⁵⁺ species. In-situ DRIFT analysis further revealed the organic fingerprint of C2 hydrocarbons (ethane and ethylene), cyclohexane, and benzene, indicating significant production of aromatic compounds. The superior activity and stability of the catalyst are attributed to the high dispersion of molybdenum species within the zeolite, as verified by XRD and TEM. The catalytic performance and properties of the synthesised catalysts were compared with those of a conventionally impregnated catalyst.