Unveiling the d-Orbital Occupancy Driven Push-Pull Effect on Pathway Selectivity in 1,2-Dichloroethane Catalytic Combustion

Unraveling the link between electronic structure and reaction pathway is key to regulating 1,2-DCE catalytic combustion and reducing toxic byproducts. In this work, we dope the full series of 3d transition metals (Sc to Zn) into SBA-15-supported LaMnO3 perovskite and show that dopant d-orbital occupancy determines the reaction pathway via a directionally polarized push-pull configuration. Low-occupancy dopants (Sc, Ti, V, Cr) withdraw electrons from Mn, forming electron-rich sites that donate electrons to adsorbed 1,2-DCE, moderately activating the C─H bond and driving the dehydrochlorination pathway to produce VC. In contrast, high-occupancy dopants (Fe, Co, Ni, Cu, Zn) push electrons toward Mn, generating electron-deficient sites that strongly extract electrons from 1,2-DCE, thereby promoting C─Cl bond cleavage and oxygen incorporation to yield ECH. Using S-LMO-V (T_90% = 199.7 °C) and S-LMO-Cu (T_90% = 224.8 °C) as representative catalysts, S-LMO-V exhibits higher activity, with a degradation pathway dominated by the less toxic VC, attributed to its moderate adsorption strength and the lower dechlorination barrier provided by electron-rich V sites. Conversely, electron-deficient Cu sites over-stabilize the substrate and steer the reaction toward ECH. This work establishes the d-orbital-mediated push-pull effect as a generalizable descriptor for pathway selectivity, guiding selective combustion of chlorinated VOCs and beyond.