Aldol condensation of furfural and acetone on layered double hydroxides

The Aldol condensation of furfural (Fur) with acetone (Ac) to 4-(2-Furyl)-3-buten-2-one (FAc) is one of the most important processes in the aqueous-reforming of oxygen-containing biomass derivatives and has been carried out in the presence of solid-base catalysts, calcined-rehydrated Layered Double Hydroxides (LDH). The Mg-Al Layered Double Hydroxides has been prepared by the coprecipitation, calcination and regeneration from mixed oxides by rehydration. The catalyst prepared with different Mg/Al molar ratios showed different catalytic performance and the best catalyst was with the Mg/Al molar ratio of 2.5. Phenol adsorption showed that the best catalyst had the largest numbers of accessible basic sites. The appropriate rehydration temperature and time for mixed oxides obtained by calcination were also investigated. The Mg-Al LDH catalysts can be regenerated by calcination at 773 K and rehydration in decarbonate water, but the regeneration is complex and incomplete. In addition, the catalyst calcined at high temperature also had activity, which was attributed to the formation of the Mg-Al spinels.