Different morphologies of SiO2@Mg-Al-LDH nanocomposites as catalyst for the synthesis of propylene glycol methyl ether

Abstract

Layered double hydroxide (LDH) has been recognized as one type of the most promising shell material. In this contribution, SiO2@Mg-Al-LDH core-shell nanocomposites with different shell morphologies were prepared and characterized via XRD, SEM, TEM, FT-IR, TG-DTA, and BET in detail. The as-prepared SiO2@LDHs exhibit different base catalysis for the synthesis of propylene glycol monomethyl ether (PGME). The results indicate that LDH shell oriented vertically on the core could be generated by the sol-gel method (SG-SiO2@LDH) and displays the highest catalytic activity and stability among three materials. The horizontally oriented shell morphology tends to be formed by the self-assembly method (SA-SiO2@LDH), which maintains the original LDH structure but unstable. The formation of a third morphology called mixed platelet is contributed to the coexistence of horizontally and vertically platelets. It has been seen in the case of co-precipitation (CP-SiO2@LDH). Integrating the experimental result analysis, synthesis methods can significantly influence the nucleation rate, which would fabricate different shell morphologies. Furthermore, core-shell nanomaterials with special morphology may have certain application prospects in solid catalysis.