Sustainable acrolein production from bio-alcohols on spinel catalysts: Influence of magnesium substitution by various transition metals (Fe, Zn, Co, Cu, Mn)

Abstract

Acrolein is a widely used intermediate of synthesis for value-added compounds in a number of domains of application. This work reports on the sustainable synthesis of acrolein by oxidative coupling of bio-alcohols, which constitutes a very promising alternative to fossil fuel-based production. The synthesis is performed in two sequential reactors, using an iron molybdate catalyst for oxidation and then a magnesium aluminate spinel where magnesium is partly or totally substituted by transition metals (Fe, Zn, Co, Cu, Mn) as a catalyst for cross-aldolization. The acid-base properties of the latter catalysts were determined using SO2 and NH3 adsorption microcalorimetry. Adsorption microcalorimetry was also used to study the adsorption properties of the reactants, with formaldehyde, acetaldehyde and propionaldehyde as probe molecules, and was complemented by a FT-IR investigation of reactant adsorption in order to better understand the mechanisms of adsorption and reaction. Acrolein production was found to be correlated to the ionic radius of the transition metals used in the catalysts, indicating that electronic effects are likely a factor influencing the acrolein production.