Growth mechanism and process intensification of Ni‐Al‐layered double hydroxide synthesized via coprecipitation

Abstract This work systematically investigated the crystallization process of NiAl‐layered double hydroxide (NiAl‐LDH) with a Ni(II)/Al(III) ratio of 3 under different crystallization conditions. The results showed that the prepared NiAl‐LDH first exhibits sheet‐like morphology, which transforms into a hexagonal platelet with further growth. The lateral size and thickness of the prepared NiAl‐LDH are ~10–284 nm and ~2–31 nm, respectively. Based on the evolution of morphology, particle size and crystallinity, the growth mechanism of NiAl‐LDH was first proposed. The growth of NiAl‐LDH in the lateral dimension was governed by Ostwald ripening, while the increase in c direction was dominated by oriented particle attachment before precipitation and dissolution equilibrium. Afterward, the growth of NiAl‐LDH was dominated by the oriented particle attachment, leading to further growth of NiAl‐LDH. Moreover, a rotating packed bed (RPB) was first adopted to crystallize NiAl‐LDH. The results show that RPB can greatly enhance the growth of NiAl‐LDH.