Syngas for Fischer-Tropsch synthesis by methane tri-reforming using nickel supported on MgAl2O4 promoted with Zr, Ce and Ce-Zr

Highlights: • Zr and CeZr presence increased reactants conversions at 750 °C. • H₂/CO ratio at 750 °C was near 2 and adequate to high chain hydrocarbons production. • Coke formation followed NMA > NCZMA > NZMA ~ NCMA trend, the same of concentration of strong base sites (%). • In situ studies showed Ni⁰ was not oxidized during tri-reforming process. -- Abstract: Nickel catalysts supported on magnesium aluminate promoted with ZrO₂, CeZrO₂ and CeO₂ were evaluated under methane tri-reforming reaction. MgAl₂O₄ synthesis was assisted by P123® surfactant, assuring high porosity. The catalysts were tested at 650 °C and 750 °C. Zr and CeZr promoted catalysts showed less coke deposition and increased conversions, mainly at 750 °C, while the non-promoted catalyst featured lowest reactants conversion due to an unstable performance caused by filamentous coke deposition. The H₂/CO ratio produced at 750 °C was at around 2, suitable to FT synthesis. In situ XPD analysis suggested nickel remained active as Ni⁰ throughout the reaction, even in the oxidant environment, containing water and oxygen, and high-temperature exposure. Considering that nickel oxidation during the process is one of the concerns related to the catalyst deactivation during tri-reforming of methane, along with carbon deposition, these catalysts are promising to active and stable syngas production.