Abstract

Novel proposed processes for H₂ production and energy generation such as partial oxidation of hydrocarbons (POX-MeO) and chemical looping process (CLP), respectively require the use of solid oxides as oxygen carriers. In POX-MeO the required oxygen for the partial oxidation of methane is provided by a transition metal oxide (MeO). First, H₂ is produced through CH₄+MeO = CO+H₂+Me. Secondly, Me is re-oxidized through Me+O₂ = MeO to regenerate the oxygen carrier. In the CL process, CH₄ is being completely oxidized through CH₂ + MeO = CO₂ + H₂O + Me producing heat and CO₂ ready for sequestration. Finally, Me is re-oxidized using air to regenerate the Me back to MeO. In both processes the regenerated MeO is sent back to the initial step to result in a cyclic operation. Continuous exposure of MeO to Redox cycles frequently produces sinterization and MeO stabilization is needed to avoid loss of activity. The objective of this study is to investigate the stabilization effect of TiO₂ in Co₃O₄ during Redox cycles to be used as an oxygen carrier using Co_xTiO_y type spinnels. Characterization of the synthesized samples included XRD, TPR, and SEM. Co₂TiO₄ and CoTiO₃ spinnels were synthesized by solid state reaction. TGA and TPR Redox performance cycles of Co₃O₄ produced sintering, while results using a Co₂TiO₄ spinnel structure suggest a strong stabilization effect of TiO₂ on Co. Ten Redox cycles using H₂ and CH₄ as reducing agents and a mixture of O₂/N₂ as oxidizer resulted in fixation of Co to TiO₂ avoiding sintering.

Recommended Citation

De los Rios, Thelma; Lardizabal Gutierrez, Daniel; Collins Martínez, Virginia; and López Ortiz, Alejandro (2005) "Redox Stabilization Effect of TiO₂ in Co₃O₄ as Oxygen Carrier for the Production of Hydrogen through POX and Chemical Looping Processes," International Journal of Chemical Reactor Engineering: Vol. 3: A33.
Available at: http://www.bepress.com/ijcre/vol3/A33