Zirconium-doped porous magadiite heterostructures upon 2D intragallery in situ hydrolysis–condensation–polymerization strategy for liquid-phase benzoylation

Abstract

Novel zirconium-doped porous magadiite heterostructures (PMH-xZr, x = Zr/Si molar ratio) are fabricated by two-dimensional intragallery cosurfactant-directing in situ hydrolysis–condensation–polymerization method of TEOS and Zr-n-propoxide from synthetic Na-magadiite and characterized systematically by XRD, SEM/(HR)TEM, ²⁹Si MAS NMR, BET, UV-vis DRS, NH₃-TPD, pyridine FT-IR, and XPS techniques. The results indicate that the obtained PMH-xZr materials possess high surface area and high thermal stability upon effective assembly of interlayer Zr-doped meso-structural silica and the layers of magadiite. The PMH-xZr samples with x < 0.2 show successful incorporation of Zr into the lattice of interlayer mesostructural silica framework leading to considerably generated Brønsted sites Zr–O(H)–Si and obviously increased Lewis sites Zr–O–Si along with well-kept layered supermicro-mesostructure, while PMH-0.2Zr shows delaminated layers. PMH-0.1Zr exhibits the highest liquid-phase benzoylation activity of anisole with benzoyl chloride (Conv. 99.5%) and yield for 4-methoxybenzophenone (4-MBP) (94.1%) due to the strongest synergy between the high concentration of surface Brønsted sites and supermicro-mesostructure. PMH-0.1Zr can be reused by no further chemical treatment for at least five runs with a slightly reduced 4-MBP yield. These PMH-xZr materials can serve as a promising solid acid catalyst and/or acidic support with high surface area and thermal stability in broad range of catalysis applications.