Preparation of niobium-based oxygen carriers by polyol-mediated process and application to chemical-looping reforming

New niobium-based oxygen carriers were prepared adopting polyol-mediated process. Four different polyols were used (diethylene glycol, triethylene glycol, tetraethylene glycol, and 1,2-propanediol) and four different quantities of water (0 mL, 1 mL, 10 mL, 30 mL, with a total volume of 80 mL of solution). Series of bulk and alumina-supported materials were prepared. Different structural and textural properties were obtained, depending on polyol type and hydrolysis ratio. After thermal treatment at 1000 °C, alumina-supported materials were evaluated in a lab-scaled fixed bed reactor. Despite a low conversion of methane due to a low content of active phase AlNbO4, they presented a high selectivity to syngas (a mixture of H2 and CO) during the first few seconds of reaction with CH4, indicating a high selectivity towards chemical-looping reforming process.