Synthesis of Glycerin Carbonate by an Environmentally Friendly Novel Catalytic Membrane of Poly(vinyl alcohol)/Deep Eutectic Solvent

A novel and eco-friendly catalytic material, poly-(vinyl alcohol)-supported deep eutectic solvent (PVA/DES) catalytic membrane, was prepared and used to produce value-added glycerin carbonate (GLC) from glycerin and dimethyl carbonate (DMC) for the first time. The heterogeneous form of catalytic membrane was prepared in the form of a film using PVA polymer as a support and an environmentally friendly DES, consisting of potassium hydroxide (KOH) and poly-(ethylene glycol) (PEG), as the catalyst. Fourier-transform infrared (FTIR) and thermogravimetric analysis (TGA) characterizations were performed to assess the functional groups and thermal stability of the PVA/DES catalytic membrane. Moreover, the change in the chemical structure of the catalytic membrane after the reaction was investigated by FTIR. The interaction between the catalytic membrane and glycerin is described by contact angle measurements. The relationship between reaction time, amount of catalyst, temperature, DMC/glycerin initial molar ratio, and reaction yield in batch reactions with PVA/DES catalytic membrane was discussed. The maximum GLC yield of 65.4% was obtained at 33% catalyst amount, 85 °C, DMC/glycerin: 3:1, and a reaction time of 4 h. The additional membrane reactor study increased the 3 h GLC yield to 74.0%. Furthermore, the effects of catalyst amount and DMC/Glycerin ratio on the reaction yield in the Response Surface Methodology (RSM) study with a central composite design were compared. It was found that the PVA/DES catalytic membrane is a suitable and green catalytic material for GLC synthesis from DMC.