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

Abstract

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 °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.

Plasma-Activated Solid Base Carbon Monolith Catalyst for Continuous Synthesis of High-Density Aviation Fuel Precursors

“…4 The steric hindrance exhibited by cyclopentanone makes its self-condensation difficult to achieve, requiring a high-efficiency catalyst to promote the reaction. 9 Homogeneous catalysts such as NaOH have been studied for the conversion of cyclic ketones to bi-and tricyclic sustainable aviation fuels by self-condensation reactions. 10 NaOH has been reported to have excellent catalytic activity in the aldol condensation of cyclic ketones and furfural.…”

Mesoporous-Layered Double Oxide/MCM-41 Composite with Enhanced Catalytic Performance for Cyclopentanone Aldol Condensation

“…In this field, great efforts have been made by Dumesic [8,9], who first transformed furfural and other platform chemicals into diesel range alkanes via aldol condensation, followed by hydrogenation. These alkanes prepared from furfural were mostly chain alkanes with low density (<0.77 g mL −1 ); therefore, the synthesis of renewable high-density cyclic alkanes is attracting more attention for satisfying the specification of jet fuels [6,7,[10][11][12].…”

“…It possesses a ring structure and two carbon atoms with α-H, making it a promising building block for producing cyclic alkanes [11,12]. To date, various heterogeneous metal oxide catalysts (e.g., MgO, CaO, CeO 2 , ZrO 2 , TiO 2 -ZrO 2 , MgO-ZrO 2 ) have been developed to catalyze the aldol condensation of CPO for producing cyclic fuel precursors [10,[13][14][15]. The acid-base properties of catalyst have great impact on its activity and selectivity.…”