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During co-hydroprocessing of petroleum fractions with liquid biomass, carbon monoxide (CO), carbon dioxide (CO 2 ) and water (H 2 O) constitute some of the main by-products which take place due to the oxygen content of biomass. This study focuses on determining the H 2 O and CO effect on HDT reactions, as there is a certain controversy associated with their role. H 2 O and CO are artificially added during gas-oil catalytic hydrotreatment to investigate their influence in the potential biomass (i.e. lipids, bio-oil, tallow oil) catalytic co-hydroprocessing with fossil-based fractions for the production of hybrid fuels. Based on the experimental results, it is clearly inferred that the H 2 O role is neutral on heteroatoms' removal. On the contrary, CO has a suspending role not due to the resulting hydrogen partial pressure reduction, but rather to the inhibition of the catalyst active sites. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the effect of CO2 on catalytic hydrotreatement of gas-oil to evaluate the potential of catalytic co- hydroprocessing of petroleum fractions with liquid biomass. A total of six experiments were conducted under low (330 °C), mild (345 °C) and severe (360 °C) operating conditions employing straight run gas-oil as the petroleum fraction feedstock. During three of these experiments CO2 was artificially added to the reaction system to assess its impact on the associated catalytic reactions over a commercial CoMo/Al2O3 catalyst. The dedicated experiments revealed a suspending role of CO2 on hydro- desulfurization (HDS), hydro-denitrogenation (HDN), and saturation reactions, which is attributed to the subsequent hydrogen partial pressure reduction of the reacting system caused by the competitive water gas-shift and methane reforming reactions. [ABSTRACT FROM AUTHOR]