Molybdenum-Containing Dendritic Mesoporous Silica Nanospheres as Effective Catalysts for Synthesis of Propylene Glycol Methyl Ether Acetate.

A series of Molybdenum-containing dendritic mesoporous silica nanosphere (Mo-DMSN) catalysts were prepared by a one-step synthesis method and used as highly efficient catalysts for the transesterification of propylene glycol monomethyl ether (PM) and methyl acetate (MA) to propylene glycol methyl ether acetate (PMA). The nMo-DMSN catalysts were characterized by XRD, SEM, XPS, FT-IR, N2 adsorption–desorption and NH3-TPD. The results of FT-IR and XPS confirmed that Mo species enter into the framework of DMSN. Compared with those of the DMSN catalyst, the pore diameters and the acid density of the catalysts increased after the introduction of Mo. According to the results of NH3-TPD, the nMo-DMSN had both weak and medium acid sites, and the acid density increased with the increase of Mo content. The catalytic performance of these catalysts increases in the order of 0.075Mo-DMSN≈0.053Mo-DMSN≈0.036Mo-DMSN > 0.017Mo-DMSN > DMSN, which is consistent with the acid density of the catalysts. The 0.036Mo-DMSN catalyst still had excellent catalytic activity after 5 cycles. Therefore, the Mo-DMSN had significant activity and stability in the transesterification of PMA. [ABSTRACT FROM AUTHOR]