Ceria promoted deoxygenation and denitrogenation of Thalassiosira weissflogii and its model compounds by catalytic in-situ pyrolysis

• Thalassiosira weissflogii and its model compounds were pyrolysed over ceria catalysts.
• The highest liquid yield (25.8%) was obtained in presence of CeO2 at 500 °C.
• Ceria catalysts increased aliphatics and decreased oxygenate compounds.
• Dehydration and decarboxylation were the main deoxygenation reactions.
• Ceria catalysts consistently reduced N-content in bio-oil.

Pyrolysis of microcrystalline cellulose, egg white powder, palm-jojoba oils mixtures Thalassiosira weissflogii model compounds was performed with CeO2 at 500 °C, to evaluate its catalytic upgrading mechanism. Light organics, aromatics and aliphatics were originated from carbohydrates, proteins and lipids, respectively. Dehydration and decarboxylation were the main reactions involved in the algae and model compounds deoxygenation, while nitrogen was removed as NH3 and HCN. CeO2 increased decarbonylation reactions compared to in absence of catalyst, with production of ketones. The results showed that the catalysts had a significant effect on the pyrolysis products composition of T. weissflogii. CeO2, NiCeAl2O3 and MgCe/Al2O3 catalysts increased the aliphatics and decreased the oxygen content in bio-oils to 6–7 wt% of the algae starting O2 content. Ceria catalysts were also able to consistently reduce the N-content in the bio-oil to 20–38% of that in the parent material, with NiCe/Al2O3 being the most effective.