Revealing
the catalytic oxidation mechanism of volatile organic
compounds (VOCs) is insightful for the development of efficient catalysts.
However, because of the complicated interactions and a large number
of intermediate species during the reactions, the analysis of the
entire reaction mechanism (including the activation modes of reactant
molecules and the rate-limiting step) remains a great challenge. Herein,
the YMn2O5 mullite catalyst was proposed to
demonstrate how to distinguish the deep oxidation difference among
C3–C4 alkanes and olefins via combining experiments and theoretical
calculations. The YMn2O5 catalyst prepared via
the hydrothermal method displayed a superior catalytic behavior with
a low T90 temperature (C3H8 at 250
°C; C3H6, C4H10,
and C4H8 less than 200 °C) (1000 ppm of
C3–C4 and 10% O2 balanced with He, WHSV = 30 000
mL/g·h). The catalytic activity remained the same after continuous
reaction for 100 h at 275 °C for each reactant. Overall, the
YMn2O5 mullite catalyst exhibits excellent durability
with no activity declines for 400 h. Combined with TPD, DRIFTS, XPS,
and DFT analysis, surface oxygen species were found to be active for
the oxidation. Owing to the difference of the HOMO induced partial
charge distributions between alkanes and alkenes, the dehydrogenation
of the end-site C–H of propane is the first step prior to the
crucial conversion of acrylate over surface labile oxygen in an octahedral
ligand unit. For propene oxidation, the CC double bond is
preferentially attacked by two surface oxygen atoms belonging to the
octahedral and pyramid ligand units with the crucial step of acetate
decomposition. These findings provide insights into the oxide catalyst
design toward the complicated VOCs oxidation from a fundamental point
of view.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.