Acrolein production from a mixture of methanol and ethanol : impact of the acid-base properties of spinel catalysts

V. Folliard (1) , G. Postole (1) , Devaux J.F. , Dubois J.L. , Auroy P. , Bonneau L. , A. Auroux (1)

1 ATARI - IRCELYON-Approches thermodynamiques, analytiques et réactionnelles intégrées

Acrolein is widely used as a very good intermediate for numerous syntheses such as methionine, acrylic acid or biocides. Nowadays, acrolein is obtained by oxidation of propylene. Recently, due to the need of reducing greenhouse gas emission and finding more environmental friendly methods of production, new processes have been developed to produce acrolein starting from renewable resources [1-2]. One of these promising ways is the oxidative coupling of biosourced alcohols. In this two-step process, the first stage involves the oxidation of a mixture of methanol and ethanol to formaldehyde and acetaldehyde which is directly followed by an aldolisation and dehydration of aldehydes to get acrolein [3-4]. The goal of the present research was to synthesize acrolein in a single reactor from alcohols oxidative coupling (methanol + ethanol) thanks to the development of catalysts with a good balance between basic and acidic sites. In order to increase selectivity in acrolein without formation of too much CO+CO2, catalysts based on spinels with various Mg/Al ratios were investigated. The basic and acidic properties of the catalysts were determined by adsorption microcalorimetry of SO2 and NH3 respectively, to obtain the number, strength and strength distribution of the active sites. Moreover, to investigate the affinity of catalysts for the reactants, adsorption microcalorimetry of acetaldehyde and formaldehyde have been performed. Then, catalytic reaction were done in presence of oxygen to study how the acidic and basic properties can influence the activity and selectivity towards acrolein. Among spinel catalysts, 1Al2O3 1MgO shows the best acrolein yield and selectivity (respectively 27 and 33%) at 285°C and 5000 h-1 of GHSV and CO+CO2 production of 10%. It has been observed that an increase of basicity was detrimental to the production of acrolein (Fig 1). Interestingly, consecutive adsorption of formaldehyde and acetaldehyde were performed in order to enter more deeply in mechanism of acrolein formation. The role and the influence of the cooperation between acidic and basic sites on the acrolein production will be discussed. Bibliography [1] W.G. Etzkorn, in Kirk-Othmer Encyclopedia of Chemical Technology, 2009, 1 [2] R.K. Grasselli, Top. Catal., 2002, 21, 79 [3] A. Lilić, et al. ChemSusChem 2017, 10, 1916 [4] A. Lilić, et al. ChemSusChem 2017, 10, 3459

Domaines: Catalyse; Environnement et Société

V. Folliard, G. Postole, Devaux J.F., Dubois J.L., Auroy P., et al.. Acrolein production from a mixture of methanol and ethanol : impact of the acid-base properties of spinel catalysts. IUPAC Paris 2019, Jul 2019, Paris, France. ⟨hal-02187613⟩