Non-oxidative coupling of methane via selective passivized catalysis

Methane activation remains a grand challenge in catalysis science and reaction engineering. Under nonoxidative conditions, this is likely not due to the intrinsic inertness of CH₄ molecules, but because activity must be balanced with selectivity and long-term stability of catalysts. We clarify that the C-H bond dissociation enthalpy (BDE) of methane, while large, is a poor metric for the catalytic reactivity of methane: BDE is a gas-phase quantity that neither dictates the reaction free energy nor the site-specific activation free energy relevant to reaction pathways. Guided by thermodynamic analysis of non-oxidative coupling of methane (NOCM) and kinetic evidence on Pt-based catalysts, we show that rapid deactivation via deep dehydrogenation and coking dominates catalytic performance limits. We advance selective passivized catalysis (SPC) as a differentiated catalyst design strategy in which a fraction of overly active sites is deliberately shielded, ex situ (e.g., alloying, support modification, geometric confinement) or in situ (reaction-induced passivation), to suppress undesired pathways while preserving sites that promote desired products. SPC reconciles activity with stability and has delivered sustained NOCM performance with C₂ selectivities >90% on Pt-Bi/ZSM-5 and stable operation using Pt nanolayers on Mo₂TiC₂T_x MXene. We outline mechanistic scenarios for solely heterogeneous NOCM and highlight operando characterization (EPR, MBMS) to resolve radical vs. surface-mediated routes. In this Feature Article, we review that selective passivized catalysis provides a rational blueprint to stabilize methane activation and bring NOCM closer to practical relevance.