processes for thermal conversion of biomass are provided . the processes involve upgrading the pyrolysis vapor from a pyrolysis reactor . the steps include thermally converting a biomass feedstock in a pyrolysis reactor , recovering a pyrolysis vapor from the reactor , passing the pyrolysis vapor in contact with a water - gas shift reaction catalyst and a hydrotreating catalyst , and converting the resulting upgraded pyrolysis vapor into a liquid product . the resulting biooil liquid product is more refined , and the overall processes offer economic and energy efficiency .