Optimal Simultaneous Production of Hydrogen and Liquid Fuels from Glycerol: Integrating the Use of Biodiesel Byproducts

In this paper, we present the optimization of the production of hydrogen and/or liquid fuels from glycerol. We propose a limited superstructure embedding a number of alternative technologies. Glycerol is first reformed using either aqueous phase reforming, steam reforming, or autoreforming. The gas obtained is cleaned, and its H 2 to CO ratio is adjusted (bypass, PSA, and/or water gas shift). Next, the removal of CO 2 is performed by means of PSA, and the syngas is fed to the Fischer–Tropsch reactor. The products obtained are separated while the heavy fraction is hydrocracked. The optimization of the system is formulated as a mixed integer nonlinear programming (MINLP) that is solved first for the optimal production of hydrogen alone and next for the simultaneous production of liquid fuels and hydrogen. The production of hydrogen is competitive with that obtained from switchgrass as long as the glycerol price is below $0.05/lb ($0.110/kg) using aqueous phase reforming. For the liquid fuels to be attractive, the glycerol price must be below $0.025/lb ($0.055/kg) using autoreforming. The option of integrating this facility with a biodiesel one is promising from an economical point of view.