Atomic-Nanoscale Reassembly of Nanoparticles and Precursors Driven by Nanofluid Feed Flame

The flame-driven reassembly of nanoparticles mixed with precursors via nanofluid feed is demonstrated, and the underlying assembly mechanism is systematically elucidated. A variety of nanoparticles are directly dispersed into Ca-Fe precursor solutions to form nanofluid for liquid-fed flame synthesis of supported catalysts in this approach. Depending on the nanoparticle composition, the flame process yields distinct products, including amorphous Ca-Al-Fe oxides, crystallized Ca₂Fe₂O₅/MgO, and CaTiO₃-amorphous Fe oxides, confirming the occurrence and tunability of nanoparticle-precursor assembly in the flame environment. During assembly, crystalline phases with low melting points and broad compositional ranges are preferentially formed, while confusion criteria can result in amorphous structures. The reassembled Ca₂Fe₂O₅/MgO is applied to the chemical looping reforming of toluene, achieving a syngas yield of 3.36 Nm³/L and a toluene conversion of 92.8%. The resulting syngas exhibits a purity above 90% with an H₂/CO ratio exceeding 2. Flame synthesis enabled by nanofluid feed thus represents an efficient and versatile strategy for producing thermally stable supported catalysts.