Abstract
Co-processing biocrude oils in existing fluid catalytic cracking (FCC) units can significantly expand the use of renewable bioenergy resources with acceptable capital expenditures. Considering the instability and high corrosivity of bio-oils, extensive studies have been done on the aging of bio-oil and corrosion of low-alloy and stainless steels under transportation and storage conditions at temperatures < 80 °C, which is much lower than the FCC feeding temperatures of 100–300 °C. In this work, the thermal stability and corrosivity of pinewood-derived bio-oil were evaluated by aging at 150 °C and immersion experiments at temperatures of 80, 150, and 220 °C. Phase separation was observed in aged samples. Viscosity measurements and thermogravimetric analysis were conducted on the aged bio-oil samples. In parallel, the corrosion modes and extents of two structural materials (UNS K02600 carbon steel and UNS S30403 stainless steel) were evaluated using microscopy and mass change measurements after immersion tests. UNS S30403 exhibited an acceptable corrosion rate of 0.29 mm/y at 80 °C, but its corrosion rate increased by one order of magnitude when increasing the temperature to 150 and 220 °C. UNS K02600 behaved more poorly at each testing temperature. Thermogravimetric analysis of aged bio-oil and bio-oil from immersion tests revealed a combined effect caused by lixiviated metal ions on facilitating bio-oil aging and phase separation on increasing bio-oil corrosivity. Post-characterizations were performed to identify the corroded surface morphology.
