Fluidized bed reforming of methane by chemical looping with cerium oxide oxygen carriers

Abstract

Methane reforming is an industrial process for hydrogen production having a high CO2 footprint that can be mitigated either by using renewable methane, or by recycling carbon dioxide from capture. Methane reforming assisted by an oxygen carrier was currently investigated, being an attractive option for production of hydrogen and carbon monoxide mixtures. The distinctive aspect of present research was the development of three different granular materials based on CeO2 to be used in fluidized beds, obtained by pelletization and calcination at 900 and 1200 °C of CeO2 or CeO2/Al2O3 powder. Fluidization and abrasion tests were performed at cold and hot conditions, showing the best attrition resistance of materials calcined at the highest temperature, with attrition rate equal to 0.3 %/h. Conversely, thermogravimetric tests at 900 °C revealed the best performance of CeO2 granules sintered at lower temperature with respect to the others in terms of oxygen supply capacity, achieving 0.55 of conversion degree. Reforming and regeneration cycles were performed in fluidized bed at 940 °C with CeO2/Al2O3 granules, providing instantaneous methane conversion up to 37 %, high carrier conversion (0.87) and low carbon deposition (2.9 mg/g) during the reforming step.