Solvent-Free Aldol Condensation of Cyclopentanone with Natural Clay-Based Catalysts: Origin of Activity & Selectivity

The conversion of biomass resources into high-value fuels and chemicals using thermochemical methods has become an attractive method of energy utilization. In this study, natural minerals were used as raw materials; the acidic sites were introduced by ball-milling modification, and the aldol condensation reaction of the biomass-based cyclopentanone molecule was carried out under solvent-free conditions. It was found that the SO3H-APG catalyst-with strong medium-based sites when the -SO3H loading was 4 mmol/g-exhibited excellent acid-base co-activation effects and a significant catalytic effect in the cyclopentanone condensation reaction. The optimization of the reaction conditions showed that the conversion of cyclopentanone reached 85.53% at the reaction temperature of 150 degrees C and reaction time of 4 h. The selectivity of the dimer and trimer was 69.04% and 28.41%, respectively. The investigation of the cyclopentanone condensation mechanism and kinetic analysis showed that the acid-base presence of an acid-base bifunctional catalyst was important to facilitate the condensation reaction. This research route is in line with the concept of sustainable green production and also provides a promising pathway for catalyst design and the synthesis of long-chain hydrocarbons.