Construction of Solely Lewis acidic sites on Zr-MCM-41 and the catalytic activity for the Prins condensation of β-pinene and paraformaldehyde to nopol

This work has firstly constructed purely Lewis acidic sites on MCM-41 successfully, for which Zr-MCM-41 catalysts with different Zr contents are prepared through the hydrolysis of ZrOCl2 on MCM-41, followed by calcination. Thus-prepared materials possess typical hexagonal mesostructures, irregular morphologies, large surface areas, and large pore sizes, as revealed by XRD, SEM, TEM, N-2 adsorption, and DRIFT FTIR. UV-vis, Raman and XPS spectra prove the formation of isolated zr=o species in high dispersion on the surface of MCM-41. NH3-TPD analysis shows that the acid intensity of the catalysts is proportional to the content of Zr, and the acidity of Zr-MCM-41 with the Zr content of <0.5% is very weak. Pyridine-IR spectra show that the surface acidity is mainly consisted of Lewis acidity, and solely Lewis acidic sites are constructed on Zr-MCM-41(550) with a low Zr content < 0.5 wt%. More Lewis acidic sites exposed on the surface of Zr-MCM-41 are considerably important for promoting the titled Prins condensation. (C) 2016 Elsevier Inc. All rights reserved.