Separation of biobutanol from synthetic fermentation mixtures using unidirectional small pore pure silica zeolites

Abstract

[EN] The adsorptive vapour phase separation of 1-butanol from a synthetic ABE (acetone, 1-butanol, ethanol) mixture has been studied for the first time on a set of unidirectional small pore pure silica zeolites with ITW, MTF, RTH and STT structures with different pore size and topology. With this systematic approach, we provide insight into the structural and surface properties that can improve the vapour phase recovery of biobutanol. The influence of operation parameters, such as the temperature (40-80 degrees C), the total flow, and presence/absence of humidity and CO2 have been studied. For this application, adsorbents need to possess pore openings with one of their di-mensions larger than 4.1 angstrom and cavities with diameters above 7 angstrom. Si-STT zeolite presents a remarkable selec-tivity towards 1-butanol, which is not affected by the presence of water or CO2 in the mixture or by an increase in the temperature. Si-STT results an excellent and robust adsorbent for this separation at conditions close to those of the headspace of the ABE fermenter, achieving purities of 90-93% at recoveries between 90 and 96%.