Preparation and characterization of LaCrO3 and Cr2O3 methane combustion catalysts supported on LaAl11O18- and Al2O3-coated monoliths

Structured Perovskite-Based Catalysts and Their Application as Three-Way Catalytic Converters—A Review

“…On the contrary, extensive interaction exists on γ-Al 2 O 3 supported systems, which results, as earlier mentioned, in the formation of less active spinel structures, simple oxides and aluminate phases [66,130]. LaAl 11 O 18 and LaCr 1−x Al x O 3 form upon solid-state reaction between LaCrO 3 and γ-Al 2 O 3 at high temperature [131] while Mn from LaMnO 3 is incorporated in the alumina lattice even at low temperature [129]. Such chemical interactions can be limited by precoating a La 2 O 3 layer on alumina prior to the application of the perovskite phase [66].…”

“…Washcoated supported perovskite-type catalysts can be prepared by impregnation or deposition-precipitation of the active phase on an oxide support powder (e.g., γ-Al 2 O 3 , ZrO 2 , MgO) either before [39] or after [127][128][129][130][131][132] that the latter is washcoated on the structured carrier. This produces a homogeneously distributed active phase [127] on a porous support firmly anchored to the walls of the substrate [66,128].…”

“…Deposition on a porous oxide support significantly increases the dispersion of the perovskite material, which enhances the catalytic performance [128,129,131]. Cimino et al compared fresh unsupported and ZrO 2 -supported LaMnO 3 monolithic catalysts.…”

“…A three times higher specific rate of methane combustion per gram of catalyst (corresponding to a 14-fold increase in the specific rate per gram of active phase) was obtained on the supported system [128]. Activity enhancement is however not always so spectacular [119] and has a limit: large perovskite crystals form upon increase of the perovskite-type oxide loading and exposure to high temperatures, which leads to pore blocking and loss of dispersion [39,[128][129][130][131]. The decrease of activity was reported to be proportional to the loss of specific surface area: a reduction of both these parameters by a factor four was observed after treating a monolithic γ-Al 2 O 3 supported LaMnO 3 catalyst for 9 h at 1100 °C [127].…”

Monoliths: A Review of the Basics, Preparation Methods and Their Relevance to Oxidation

“…It has been shown that perovskite-based catalysts can be deposited onto cordierite monoliths via deposition-precipitation [263]. In addition, it has been reported that LaMnO 3 supported on La-γ-Al 2 O 3 coated cordierite is more active and thermally stable, in the catalytic combustion of methane, than the catalyst in powder form [126,264].…”