This work proposes an innovative catalytic pyrolysis process that converts bio-refinery residues, such as spent grains, into intermediate bio-oil with improved properties compared to traditional bio-oils, which allows the use of existing crude-oil refinery settings for bio-oil upgrading into fuels. The integration of bio-oil into a crude-oil refinery would decrease the economic disadvantage of biomass compared to fossil fuels. The catalytic pyrolysis was able to produce bio-oil with a lower O and N content and high levels of aliphatics and H by using activated serpentine and olivine at 430–460 °C. The activated materials seem to be beneficial to the bio-oil energy content by increasing it from less than 20 MJ kg−1 in the original biomass to 26 MJ kg−1. Approximately 70–74 % of the starting energy remains in the bio-oil using activated olivine (ACOL) and activated serpentine (ACSE) at 430 °C, whereas only 52 % is retained using alumina (ALU) at the same temperature. There was a strong reduction of the O content in the bio-oils, and the deoxygenation power decreased in the following order: ACOL>ACSE>ALU. In particular, ACOL at 430–460 °C was able to reduce the O content of the bio-oil by 40 %. The oxygenated bio-oil macromolecules interact in the catalyst’s active sites with the naturally present metallic species and undergo decarboxylation with the formation of C5–C6 O-depleted species.