Olefin Production Via Plasma Non-Oxidative Coupling of Methane Using Porous and Hollow Silica Catalysts
2025 AIChE Annual Meeting
Olefin Production Via Plasma Non-Oxidative Coupling of Methane Using Porous and Hollow Silica Catalysts
Non-oxidative coupling of methane (NOCM) has attracted growing attention as an alternative source of producing valuable hydrocarbons to prevent reliance on crude oil. Non-thermal plasma (NTP) technology can be used to drive NOCM reaction at low temperatures, offering an alternative to the harsh conditions required for traditional thermal NOCM. In NTP NOCM, methane is activated with plasma and in the presence of a catalyst to form methyl radicals whose coupling form value-added hydrocarbons, such as C2 (ethane, ethylene, and acetylene), C3 (propane and propylene), and even C4+ molecules. The combination of Na2WO4 and Mn2O3 (NWMO) has been shown as one of the promising catalysts for this reaction. Na2WO4 facilitates the formation of carbon radicals, while Mn2O3 provides a surface for carbon coupling.
Herein, we present a comparison of two high-performing catalysts using Na2WO4/Mn2O3 supported on morphologically varied silica supports. The first catalyst was synthesized by stepwise depositing of NWMO on a mesoporous silica support (mSiO2), while the second was prepared using hollow silica spheres (HSS) as the support. Under plasma conditions, the mSiO2-based catalyst achieved C2+ selectivity of nearly 94% and a C2+ yield of 20%, consistent with the performance of many reported catalysts. The HSS-based catalyst, however, delivered even higher C2+ yields due to its ability to confine carbon radicals within the silica spheres, enhancing coupling efficiency and reducing side reactions through a shielding effect provided by its hollow cavity.
