Upgrading bio-oils obtained from bio-ethanol and bio-diesel production residues into bio-crudes using vis-breaking

Abstract

Upgrading of bio-oils obtained from rape seed meal and wheat spent grains was carried out by a Thermo-t process similar to vis-breaking at 350, 400 and 410 °C at pressure ranging from 10 to 40 bars of nitrogen. About 35–40% of the energy contained in the virgin biomasses was converted into bio-crudes with 3–7 wt% oxygen. The effect of temperature on yield and quality of the bio-crudes from the Thermo-t process was studied. Overall, the process generates two different upgraded products, a liquid called bio-crude and a solid namely bio-coke. The experimental data show an effective upgrading of pyrolytic oils leading to the formation of 10–20 wt% of bio-crude with oxygen contents below 10 wt% and volatiles distribution close to conventional crude oil. The energy needed by the overall processes is estimated to be about 17% of the feedstock energy content and this value is comparable to a crude oil refinery where the energy need is about 15%. An important chemical transformation of bio-crude functionality from mostly aromatic pyrolytic bio-oil to a mainly aliphatic bio-crude has been assessed, representing a low cost solution for the high oxygen content of bio-oils. Furthermore, the addition of water was evaluated in order to enhance the deoxygenation of pyrolytic bio-oil in comparison to work done on upgrading crude-oil heavy vacuum residues.