Raw glycerol re-valuing through etherification with isobutylene: process design and techno-economical assessment

Abstract

This study evaluates the techno-economic feasibility to produce tert-butyl ethers of glycerol in Colombiausing glycerol obtained from biodiesel production. The major drawback of this process is related to thehigh costs associated to the isobutylene reagent used for this reaction. Three possible scenarios, usingisobutylene: glycerol molar ratios of 2:1 and 4:1, have been evaluated by simulation and technoeconomicalassessment using pure isobutylene, C4 fraction and a mixture of C4 and isobutylene as well asa refining stage for crude glycerol. The desired product, a mixture of di- and tri- ethers of glycerol (h-GTBE) was obtained in high amounts for the three scenarios (92–99 wt.%) and a direct relation betweenproduction cost and raw material cost was established. The prices for h-GTBE were higher than theproposed selling prices; however, the formation of byproduct (C4 fraction) can make the processcompetitive. h-GTBE production did not have a competitive price for any scenario at high isobutylene:glycerol molar ratio. The production price was lowered by around 20% for all scenarios when crudeglycerol was considered. Finally, competitive price of h-GTBE (0.96 $/kg) and NPV positive was obtainedusing a mixture of C4 and isobutylene and crude glycerol.