Thermal
deoxygenation (TDO) is a promising reaction scheme for
producing low oxygen bio-oil from biomass carbohydrate. The primary
step in bio-oil production involves pyrolysis of alkaline earth metal-neutralized
biomass hydrolysates at 723 K yielding bio-oil, chars, carbonates,
and light gases. Reactor scaling from bench to floor-scale, however,
reduced carbon yields from 80% to 48% of theoretical, respectively.
This paper details a two-stage process to intensify the TDO process,
improving carbon yields to 79% of theoretical. The scheme involves
a 523 K thermal pretreatment (stage I) to yield a polysalt and transition
of a melt-phase. The resulting solid polysalt is reduced to powder
to improve material handling and reaction rates during decomposition
at 723 K (stage II). Resulting bio-oil yield is shown to improve from
0.082 to 0.16 kg-oil/kg-feed. A two-step reaction model is developed
detailing the reaction rates and regimes which can guide continuous
process design efforts.