Formulation of two monofunctional catalysts for CH4 upgrading

Abstract

Natural gas will play a significant role in the transition from fossil to green(er) energy production. Its major component, methane (CH4) is an attractive resource to co-generate hydrogen (H2) and added value chemicals (important building blocks such as olefins and aromatics) for petrochemistry. We highlight the advantage of using a novel dual catalyst system containing a monofunctional Al-free metallic single site catalyst referred as S-Mo (Si/Al ∼ ∝) where Mo is atomically dispersed in the zeolitic framework and a monofunctional acidic H-ZSM-5 catalyst referred as S-Al (SiAl = 128) to achieve superior yields of high value products. Under severe reaction (850 ºC) and regeneration (700 ºC) conditions, the Mo-S catalyst is stable and does not suffer from irreversible structural damage by losing its Mo atomic dispersion, and deactivation by coke deposition, thus ensuring steady catalytic performances in multi-cycle catalytic tests. Conversely, the current bifunctional catalysts prepared by Mo impregnation on an acidic catalyst suffer from irreversible damage during coke combustion due to the formation of Al₂(MoO₄)₃ or AlMoO6 Anderson entities. This new approach opens novel and promising pathways to develop methane upgrading processes based on the physical separation and operation of a non-deactivating metallic catalyst and a regenerable acidic catalyst.