The effects of cerium addition on the physical-chemical properties and CO oxidation activity of nanocomposite MnCeOx catalysts (0<=?Ce<=1) have been assessed. The kinetics of the CO oxidation on a typical nanocomposite MnCeOx catalyst (M5C1) were probed by temperature programmed catalytic reaction tests in the range of 293-533K. A systematic study of the interaction pattern of the catalyst with reagent and product molecules shows easy reactivity of surface oxygen to CO, low mobility of lattice oxygen and weak surface affinity to CO2. Systematic evidences on mechanism and intermediates signal an extrafacial redox path, triggered by the abstraction of oxygen atoms in the neighbouring of surface-active MnIV sites, and sustained by O2 species adsorbed on the resulting O-vacancies. A Langmuir-Hinshelwood (L-H) type reaction mechanism leads to a formal kinetic model fully predicting the CO oxidation functionality of the MnCeOx catalysts.
A New Class of MnCeOx Materials for the Catalytic Gas Exhausts Emission Control: A Study of the CO Model Compound Oxidation
ARENA, FRANCESCO;PALELLA, ALESSANDRA;FAZIO, BARBARA;SPADARO, LORENZO
2019
Abstract
The effects of cerium addition on the physical-chemical properties and CO oxidation activity of nanocomposite MnCeOx catalysts (0<=?Ce<=1) have been assessed. The kinetics of the CO oxidation on a typical nanocomposite MnCeOx catalyst (M5C1) were probed by temperature programmed catalytic reaction tests in the range of 293-533K. A systematic study of the interaction pattern of the catalyst with reagent and product molecules shows easy reactivity of surface oxygen to CO, low mobility of lattice oxygen and weak surface affinity to CO2. Systematic evidences on mechanism and intermediates signal an extrafacial redox path, triggered by the abstraction of oxygen atoms in the neighbouring of surface-active MnIV sites, and sustained by O2 species adsorbed on the resulting O-vacancies. A Langmuir-Hinshelwood (L-H) type reaction mechanism leads to a formal kinetic model fully predicting the CO oxidation functionality of the MnCeOx catalysts.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
