Methane conversion to ethylene over GaN catalysts. Effect of catalyst nitridation

Article abstract of DOI:10.1016/j.apcata.2020.117430

Vast availability of natural and shale gases makes methane a reliable source for synthesizing valuable chemical building blocks such as ethylene. A new stable supported GaN/SBA15 catalyst from an emerging class of nitride catalysts was reported for the direct non-oxidative methane coupling to ethylene. The effect of nitridation on the catalyst properties and activity was investigated. The optimum nitridation temperatures were 700 °C and 750 °C for the GaN/SBA15 and the unsupported GaN catalyst, respectively. Supported catalysts were more stable and had 5–10 times higher product (ethylene) formation rates per gram of gallium than the unsupported catalysts due to the higher surface area (>320 vs. <20 m² g^?1) and Ga-dispersion inside the pores. Compared to the oxide precursors, the nitrides exhibited a higher atom conversion efficiency for the CH₄ carbon leading to higher ethylene selectivity (71 % for GaN/SBA15, <58 % for Ga₂O₃/SBA15) and lower coke selectivity (27 % for GaN/SBA15, 40 % for Ga₂O₃/SBA15).