Catalytic baeyer-villiger oxidation over N-doped carbon with aliphatic aldehyde: Mechanism, kinetic modeling, life cycle assessment, and techno-economic analysis

Abstract

ε-Caprolactone (ε-CL) is a key organic chemical intermediate and monomer for polycaprolactone (PCL). Developing a safe and cost-effective process for its efficient synthesis remains challenging. Here, a Baeyer-Villiger oxidation of cyclohexanone (Cy=O) using propionaldehyde (PRA) as a co-oxidant and N-doped carbon loaded carbon nanotubes (NDC@CNTs) as catalysts was conducted with a feature of the radical free reaction. The process achieves 40.14 % Cy=O conversion, 93.41 % ε-CL selectivity, and 0.36 aldehyde efficiency (AE). Good values of TON, STY and E-factor for the NDC@CNTs-catalyzed system showed the good scalability potential. The structure–activity relationship investigation showed that as the nitrogen content in NDC@CNTs increased, reaction activity rose and then declined. The ratio of pyridinic N to graphitic N (N_Py/N_G) was the key factor affecting activity. Mechanistic research revealed that NDC@CNTs boost overall reaction activity by accelerating PRA oxidation to peroxypropionic acid, which was crucial for the reaction. Kinetic studies determined the reaction orders and rate constants for Cy=O oxidation and PRA self-oxidation, establishing a predictable kinetic model through semi-batch reactions. LCA analysis reveals that this reaction system exerts a comparatively low pressure on global environmental reference systems. Moreover, the entire reaction process was meticulously designed and simulated using Aspen Plus software with a 98.77 % likelihood of positive unit profit (622.22 ∼ 2909.06 USD/t), highlighting the good economic value.