Clear microstructure–performance relationships in Mn-containing perovskite and hexaaluminate compounds prepared by activated reactive synthesis

Abstract

Microstructural properties of mixed oxides play essential roles in their oxygen mobility and consequently in their catalytic performances. Two families of mixed oxides (perovskite and hexaaluminate) with different microstructural features, such as crystal size and specific surface area, were prepared using the activated reactive synthesis (ARS) method. It was shown that ARS is a flexible route to synthesize both mixed oxides with nano-scale crystal size and high specific surface area. Redox properties and oxygen mobility were found to be strongly affected by the material microstructure. Catalytic activities of hexaaluminate and perovskite materials for methane oxidation were discussed in the light of structural, redox and oxygen mobility properties.

Reactive Grinding synthesis of La(Sr,Ce)CoO3 and their properties in toluene catalytic total oxidation

“…Calculated values are in the range of 15 to 20 nm, the unsubstituted sample having the lowest value of 15 nm. Those values are consistent with already reported perovskite synthesized by reactive grinding…”

“…The gain from the low energy ball milling process is dependent of the perovskite composition and substitution is commonly found to increase specific surface area up to a certain extent . The absence of change in SSA underlines the key role of the medium, ethanol instead of water, used during the LEBM process for the particle deagglomeration and affording a constant value of surface area whatever the perovskite composition.…”

“…Reactive Grinding (RG), as a synthesis method commonly used in metallurgy, shows attractive features including a synthesis in the absence of aqueous solution step during synthesis. RG has been proved to be a sustainable and efficient synthesis method to produce catalysts such as MnO 2 , hexaaluminates and perovskites …”

Remarkable Enhancement of O2 Activation on Yttrium‐Stabilized Zirconia Surface in a Dual Catalyst Bed

“…Simultaneously an increase of the 18 O 16 O partial . [11] The enhanced ionic conductivity of YSZ is not related to the redox couple of the yttrium and zirconium cations, which are considered to be irreducible, but results from the presence of oxygen vacancies created by the doping of zirconia with lower valence Y 3+ ions. For YSZ, the exchange between molecular oxygen and lattice atoms remains a process that requires high temperature since equilibrium is not achieved even at 973 K. To construct the dual catalyst bed, we introduced into the reactor the same amounts of solids as used previously: 13.3 mg and 20 mg for LaMnO 3 and YSZ, respectively, which corresponds to 40 wt % LaMnO 3 and 60 wt % YSZ (justification for the composition is given in the Supporting Information, Figure S2).…”

Study of Lanthanum Manganate and Yttrium‐Stabilized Zirconia‐Supported Palladium Dual‐Bed Catalyst System for the Total Oxidation of Methane: A Study by 18O2/16O2 Isotopic Exchange

“…[13,17] On the contrary,t he ratio obtained for the dual bed is higher than 1( P 32 > P 34 )u ntil 510 8Ca tw hich P 32 > 3 P 34 in the 420-450 8Ct emperature range.A tt he beginningo ft he exchange, 16 O 2 is first observed, which indicates that the oxygen exchange results rather from two successive simple exchange reactions or from an heterolytic exchangem echanism with two Oa toms ( 18 [13,17] On the contrary,t he ratio obtained for the dual bed is higher than 1( P 32 > P 34 )u ntil 510 8Ca tw hich P 32 > 3 P 34 in the 420-450 8Ct emperature range.A tt he beginningo ft he exchange, 16 O 2 is first observed, which indicates that the oxygen exchange results rather from two successive simple exchange reactions or from an heterolytic exchangem echanism with two Oa toms ( 18 …”