Process design and optimization for etherification of glycerol with isobutene

Surplus glycerol from biodiesel production can be transformed to valuable fuel additives through etherification with isobutene. Our previous work has studied the kinetics and thermodynamics of this reaction. In the present work, a novel process design is proposed. An optimization problem is also formulated to minimize the cost of production of the di-tert-butyl ethers and tri-tert-butyl ether of glycerol. The resulting mixed-integer nonlinear program enables simultaneous determination of values of key decision variables including number of column trays, feed tray location of column, volume of reactor, process flowrates etc. The optimal design leads to a minimal production cost of glycerol ethers of 1.201 $/kg, which is dominated by the cost of isobutene.