Renewable dimethyl carbonate for tertiary amine quaternisation: kinetic measurements and process optimisation

Reaction Chemistry & Engineering Pub Date: 2021-08-09 DOI: 10.1039/D1RE00191D

Abstract

Quaternary ammonium salts (QAS) are an important part of the increasing surfactant market. Conventional production processes employ toxic alkyl halides in a Menshutkin reaction with a tertiary amine (DMDA). Dimethyl carbonate (DMC) can provide a renewable route, while also leading to more benign, and non-corrosive products. This work aims to use linear ramp-flow in a plug flow reactor (PFR), combined with in-line 1H NMR spectroscopy to determine reaction kinetics. These kinetics will be used to further optimise the production process with a computational model. Solvent effects were first studied in a batch reactor. Methanol (MeOH) was found most suitable as a solvent. Subsequently, the reaction kinetics were measured in a PFR set-up. The used ramp-flow was successfully validated with data from batch and steady-state experiments. Arrhenius parameters were determined with the ramp-flow method, which proved to be an accurate and efficient technique. The kinetic data was implemented in a computational model. After validation of the model with experimental data, it was employed to extrapolate this data and optimise the reaction. The optimum QAS productivity was predicted at 122 kg h?1 L?1, obtained at 270 °C, 0.25 min residence time, and a molar ratio of 1?:?2.5?:?10 (DMDA?:?DMC?:?MeOH). These conditions would provide significant intensification of the QAS production processes.

Graphical abstract: Renewable dimethyl carbonate for tertiary amine quaternisation: kinetic measurements and process optimisation
Recommended Literature