ScholarWorks@성균관대학교

초록

An axial-time mapping (ATM) with dual time axes-catalyst-reactant contact time (t(c)) and time on stream (TOS)-is developed to clarify long-term deactivation mechanisms of iron catalysts in CO2 hydrogenation. Treating t(c) and TOS as spatially distributed variables, ex situ datasets reconstruct axial phase gradients and performance shifts. Short t(c) at the reactor inlet promotes carburization to chi-Fe5C2 and Fe7C3 in a CO-rich environment, whereas longer t(c) downstream-where H2O accumulates-favors reoxidation to Fe3O4. Over time, residual Fe3O4 is further carburized, enriching carbide phases, suppressing CO2 activation, and enabling unconverted CO2 to bypass the upper bed, thereby reducing the effective t(c). This leads to downstream migration of the CO formation zone and spatial separation of active and inactive regions. The t(c)-TOS-resolved approach provides a sensitive and practical diagnostic tool for detecting and mitigating deactivation under industrial conditions. The ATM framework offers a generalizable strategy for probing phase evolution and deactivation pathways in complex heterogeneous catalytic systems.

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