Unveiling the Active Aluminum Sites and Confinement Effects of Zeolites for N2O Decomposition

The development of sustainable catalysts for nitrous oxide (N2O) decomposition remains a significant challenge in environmental chemistry and is traditionally reliant on transition-metal-based active sites. Herein, we establish that aluminosilicate zeolites themselves are highly effective catalysts for this reaction. The activity originates from extra-framework penta-coordinated aluminum (EFAlV) species generated through controlled dealumination, rather than from conventional Brønsted acidity or residual metals. Crucially, we demonstrate that the zeolite framework topology imposes confinement effects that govern catalytic activity. Small-pore zeolites exhibit superior performance by not only facilitating the formation of EFAlV sites but also stabilizing these sites within their narrow 8-membered-ring (8-MR) channels. This confinement optimizes the local active-site geometry. Density functional theory (DFT) calculations further reveal that the transition state is stabilized by a synergistic combination of dispersion forces and a specific hydrogen-bonding network within the confined pores, which lowers the activation barrier for the rate-determining step. These findings elucidate a direct two-step reaction mechanism over the EFAlV site. This work fundamentally shifts the design paradigm for catalytic N2O decomposition, moving from the introduction of extrinsic metal species to the rational engineering of the aluminosilicate framework itself to create and stabilize the optimal EFAlV configuration. This principle provides a foundational strategy for developing economically viable, highly active, and durable catalysts for greenhouse gas mitigation.