Carboxymethyl cellulose/Zn-based metal organic frameworks membranes for pervaporation-assisted esterification reactor

Abstract

Pervaporation membrane reactors attract much attention as a promising system, in which separation and reaction are carried out simultaneously to overcome the thermodynamic equilibrium limitation and to increase the conversion by removing one or several synthesized products. For this, in this study supported carboxymethyl cellulose (CMC) membranes modified with Zn-based metal organic frameworks (Zn(SEB), Zn(BIM), Zn(BDC)Si) were developed. Transport properties of obtained membranes were evaluated in pervaporation separation of quaternary mixtures (acetic acid (AcOH), ethanol (EtOH), ethyl acetate (EtAc), water) with various compositions. CMC/Zn(BIM) membranes, possessed optimal transport characteristics, were tested in hybrid process “reaction + pervaporation” using batch pervaporation membrane reactor and compared with data obtained in batch reactor without membrane. The changes of structure and physicochemical properties of developed membranes were studied by spectroscopic, microscopic methods, thermogravimetric analysis and measurements of contact angles. To confirm findings obtained, theoretical consideration by computational methods for the CMC/Zn(BIM) membrane was carried out. It was shown that the application of optimal CMC/Zn(BIM)(10 wt%) membrane in pervaporation-assisted esterification reactor led to the formation of more than 5 times larger amount of EtAc in the reactor with decreased AcOH conversion compared to batch reactor without membrane in the separation of esterification reaction AcOH and EtOH (1/1 M) with 5 wt% Amberlyst 15 catalyst at 60 °C.