Morphology-Controlled Synthesis of Three-Dimensional Hierarchical Flowerlike Mg–Al Layered Double Hydroxides with Enhanced Catalytic Activity for Transesterification

• Published in: Industrial & engineering chemistry research 2019-05, Vol.58 (19), p.7937-7947
• Main Authors: Sun, Yongli, Gao, Xiang, Yang, Na, Tantai, Xiaowei, Xiao, Xiaoming, Jiang, Bin, Zhang, Luhong
• Format: Article
• Language: English
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/acs.iecr.9b00703

With the aim of simultaneously achieving synthesis and morphology control of three-dimensional (3D) hierarchical layered double hydroxide (LDH) by more efficient and environmentally friendly methods, a facile and cost-efficient double-drop coprecipitation method was creatively applied to fabricate 3D flowerlike microstructures (Al2O3-MgAl-LDHs) using γ-Al2O3 as a sacrificial template. The morphology evolution process and growth characteristics of Al2O3-MgAl-LDHs were investigated in detail, revealing that γ-Al2O3 not only provides an effective support for the crystal growth of LDH but also is involved in the LDH layer formation process through self-decomposition. More importantly, LDH morphologies can be regulated by varying the reaction conditions, such as the γ-Al2O3 concentration, Mg2+/Al3+ molar ratio, and pH. Additionally, a possible formation mechanism for 3D hierarchical flowerlike Al2O3-MgAl-LDHs was illustrated. Remarkably, owing to the high specific surface area and low/medium/high-strength basic sites, the as-obtained LDH after calcination exhibited excellent catalytic activity and reusability in the transesterification of glycerol with dimethyl carbonate.