Production of high content of N-methyldiethanolamine di-ester via heterogeneous transesterification

Abstract A heterogeneous transesterification over a Zn-doped CaO catalyst was developed as a new alternative route to conventional homogeneous catalysis for the production of N-methyldiethanolamine-based esterquats. In this study, the optimum heterogeneous transesterification conditions for the production of N-methyldiethanolamine di-ester, a precursor of esterquats, in high yield were determined. At a temperature of 143 °C, a vacuum of 288 mbar, a molar ratio of 2:1 (methyl ester:N-methyldiethanolamine) and a catalyst dosage of 6 %, a maximum N-methyldiethanolamine di-ester yield of 83 % was obtained. The reused catalyst showed consistent activity in three consecutive runs, demonstrating the robustness of the Zn-doped CaO catalyst in the transesterification process. This route can reduce production costs due to the reusability of the catalyst and the elimination of water consumption in the neutralisation process for catalyst removal.