Synthesis of a magnetic composite of silica with micro and nano-cobalt metallic structures from a spent catalyst (Co3O4)

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Vol. 285; p. 115921
• Main Authors: Pavoski, Giovani, Garjulli, Franco, Renato dos Santos, Caio, Lacerda Moraes, Marcelo, Alberto Soares Tenório, Jorge, Crocce Romano Espinosa, Denise
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.11.2022; Elsevier BV
• Subjects: Catalysts; Chemical synthesis; Cobalt oxides; Magnetic properties; Magnetism; Mixed cobalt oxide catalyst; Recycling; Silicon dioxide; Sol-gel processes; Thermal reduction; Mixed cobalt oxide catalyst; Recycling; Magnetic properties
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/j.mseb.2022.115921

•Obtaining cobalt from secondary sources.•Synthesis of composites from spend catalyst recycling.•Synthesis of composites with high magnetic properties.•Application of circular economy concepts adding environmental and economic values with a catalyst residue. Cobalt is a magnetism metal used in different areas, like catalysts. When these cobalt catalysts are discarded, they must be appropriately disposed of in a suitable place. This work aims to recycle and apply circular economy with the synthesis of a magnetic composite through a spent catalyst (silica/cobalt). The catalyst is composed of 93 % Co3O4 and 7 % CoO. The best parameters to perform the thermal reduction of catalysts were using a CO-CO2 atmosphere were 1 h isothermal period at 350 °C. The single CoO structure was confirmed and encapsulated in silica by the hydrolytic sol–gel method. These composites were subjected to a thermal reduction. The magnetic properties increased from a range of 0.0008–0.001 emu g-1 to 15.86–30.96 emu g-1. Thus, this work presented a viable process for recycling a spent catalyst and synthesis of a composite likely to be applied to materials to improve or add magnetism.