Carbon black and hydrogen production from upgraded fast pyrolysis bio-oils via high-temperature pyrolysis

The current manufacturing of carbon black (CB) has a high climate impact and must transition to a carbon-neutral process to meet sustainability goals. In this work, fast pyrolysis bio-oil (FPBO) from biomass and four different upgraded bio-oils (represented by synthetic mixtures made from model compounds) were used to produce renewable CB in an entrained flow reactor (EFR) at different temperatures (1100–1700 °C). The aim of this work was to investigate how the composition of bio-oils produced via the following upgrading technologies, catalytic fast pyrolysis (CFP), catalytic hydropyrolysis (CHP), slurry hydroprocessing (SHP), and slurry hydroprocessing followed by fixed bed hydroprocessing (SHP + FBHP) affects the yield and structural properties of CB. The experimental results demonstrated that CB yield from FPBO were 34–45 wt% on a carbon basis, whereas substantially higher yields (67–93 wt%) were obtained from the upgraded bio-oils depending on the specific upgrading technology and temperature of the EFR. Furthermore, the nanostructure of the CB produced at 1300–1500 °C showed similarities to that of conventional rubber-grade CB, whereas the CB produced at 1700 °C exhibited a higher degree of graphitization, with features more similar to those of conductive-grade CB. Considering the entire conversion pathway from raw biomass to CB, upgrading the FPBO prior to its use as feedstock in the CB reactor was found to increase the overall yield from ∼27 wt% for FPBO to ∼40 wt%. The highest CB yield of ∼44% was obtained for the combination of SHP + FBHP as upgrading technology and a process temperature of 1700 °C in the EFR. The results demonstrate that bio-oil upgrading could be a key strategy for maximizing biomass carbon utilization in renewable CB production.