Precious Metal Based Perovskites for Methanol Partial Oxidation

Palladium, platinum, and rhodium integrated lanthanum-transition metal perovskites were employed in methanol partial oxidation to formaldehyde. The crystallinity of these perovskites remained unchanged by incorporating up to 5 mol% noble metal cations into their frameworks. Such a cation replacement could yield a positive effect on particle size and catalyst reducibility. Under partial oxidation conditions, the reactivity and formaldehyde selectivity of perovskites without cation replacement were relatively low compared to their Pd-, Pt-, and Rh-impregnated counterparts. Most importantly, the reaction mechanism could be promoted diversely. For noble-metal-free perovskites, methanol combustion, oxidation to syngas and water, and dehydrogenation were found to be prominent. In contrast, partial oxidation to formaldehyde and dehydrogenation were the major pathways of precious-metal-integrated catalysts. Both reactions can be attributed to the elevation of formaldehyde selectivity.