Solvent effects in liquid-phase dehydration reaction of ethanol to diethylether catalysed by sulfonic-acid catalyst

The liquid-phase dehydration of ethanol to diethylether over heterogeneous sulfonic-acid catalysts was carried out in a stirred batch reactor. The different Amberlyst catalysts were found to have similar activities for this reaction; even though Amberlyst 70 showed a lower acid capacity compensated by a higher specific activity. By comparing the conversion of ethanol as a function of reaction mixture composition, it was found that reaction rates greatly depended on ethanol concentration but also on reaction mixture polarity. The swelling of the used resins could not explain the observed variations of initial reaction rate since this effect was observed both with resins and with homogeneous catalyst, i.e. p-toluenesulfonic acid. The initial ethanol concentration has a complex effect on initial reaction rates that could not be correlated by usual kinetic models. Taking account of the intrinsic reactivity trends of the SN2 etherification reaction, a strong dependence was found between solvent properties and initial reaction rate.

Figure optionsDownload high-quality image (124 K)Download as PowerPoint slideResearch highlights▶ The dehydration of ethanol to diethylether over heterogeneous sulfonic-acid catalysts. ▶ A strong dependence was found between solvent properties and initial reaction rate. ▶ Ethanol concentration has a very complex effect on the reaction rate. ▶ Such properties can be evaluated using an α scale of solvent hydrogen-bond donor (HBD). ▶ A good fit is observed using solvent scale from Kamlet–Taft.