Oxidative coupling of a mixture of bio-alcohols to produce a more sustainable acrolein: An in depth look in the mechanism implying aldehydes co-adsorption and acid/base sites

Review on Alternative Route to Acrolein through Oxidative Coupling of Alcohols

“…In a first series of spinels, where Al 2 O 3 /MgO ratios were varying, they obtained the best acrolein production with 1Al 2 O 3 ,1MgO with 27% acrolein (at 285 • C and GHSV 5000 h −1 ). Calculation of the number of strong basic to strong acidic sites ratio confirmed the previous results obtained by Lilic et al ( [38,39]), underlining the detrimental effect of an excess of strong basicity compared to strong acidity [40].…”

“…Experimental work to validate the proof of concept has been carried out over several years by Dubois, Auroux, Capron and co-workers [23,[36][37][38][39][40][41][42]. As explained above, the ultimate goal in this reaction is to have a single reactor to minimize the capital cost (at least not higher than the propylene oxidation process).…”

“…For the oxidative coupling of alcohols, where aldol condensation of formaldehyde and acetaldehyde is the consecutive step, influence of acid/base properties of catalysts has been studied by Lilic et al and Folliard et al [38][39][40][41][42]. In these experiments, the goal was to better understand the reaction mechanism, not to get the best results.…”

“…Scales of acidic and basic strength based on the average heat of probe molecule adsorption measured at the plateau of the differential heat curve, or at half coverage when no plateau is observed. See references [39,40] for more details on experimental conditions. Bold: best catalytic systems.…”

“…In 2020, Folliard et al studied the same reaction in the same conditions using spinel catalysts [40]. In a first series of spinels, where Al 2 O 3 /MgO ratios were varying, they obtained the best acrolein production with 1Al 2 O 3 ,1MgO with 27% acrolein (at 285 • C and GHSV 5000 h −1 ).…”