CO 2 Capture with Terpenoid‐based Deep Eutectic Solvents: Effects of Molecular Thermodynamics and Topology

ABSTRACT This study systematically investigates the impact of molecular isomerism on CO capture using hydrophobic deep eutectic solvents composed of DBU and four stereoisomeric terpenes: Geraniol, nerol, linalool, and L‐menthol. Experimental results demonstrate that the linear trans‐configured geraniol‐based DES exhibits superior performance (0.59 mol/mol) and favorable hydrodynamics due to lower viscosity, whereas sterically hindered isomers show reduced capacity. DFT calculations reveal a base‐promoted concerted mechanism strictly governed by steric hindrance. Consequently, activation free energy barriers follow the order: Geraniol < Menthol < Nerol < Linalool. Furthermore, microwave‐assisted regeneration achieved 86% capacity recovery within 30 s, ensuring rapid cyclability. This work establishes a rigorous structure‐activity relationship, highlighting the pivotal role of stereochemical topology in designing efficient, water‐tolerant non‐aqueous absorbents.