Synthesis of sulfated zirconium supported MCM-41 composite with high-rate adsorption of methylene blue and excellent heterogeneous catalyst

Zirconia-based mesoporous MCM-41 was successfully prepared then loaded with different content of sulfate (5, 10, 15, 25, 40 and 50 wt.%) through the wet impregnation method. The prepared samples were characterized by numerous methods like N-2 adsorption (T = -196 degrees C), FT-IR, XRD and TEM images. FTIR spectra of chemically adsorbed pyridine and non-aqueous potentiometric titration were applied to measure the acidity of SO42- / ZrO2@MCM-41 (SZ/MCM-41) catalysts. XRD results showed that the lattice cell parameter (a(0)) is increased from 37.8 to 39.5. with increasing the sulfate content. TEM images of SZ/MCM-41 samples exhibit ordered arrays of mesoporous structure with light and dark contrast and also the formation of nanorods with a diameter of 50 nm. The resulting materials showed a large surface area with a uniform pore diameter distribution. All samples displayed both Lewis and Bronsted acid sites. The catalytic activity of SZ/MCM-41 samples was examined for the preparation of 7-hydroxy-4-methyl coumarin which dramatically enhanced when compared with MCM-41 and Z/MCM-41 and the reaction continued efficiently with a yield of 99.3-89.8 % after reused four times. Furthermore, the adsorption behavior of as-synthesized samples was examined over methylene blue (MB) in the aqueous solution with varying parameters such as dye concentration, pH of the solution and contact time. The prepared samples have a good ability to eliminate the methylene blue from aqueous solution with adsorption capacity equal to 186 mg/g and the equilibrium time of 60 min.

Automated summary

Zirconia-based mesoporous MCM-41 loaded with varying amounts of sulfate were successfully prepared and characterized using various methods. The increase in sulfate content led to an increase in lattice cell parameter and the samples exhibited a large surface area with uniform pore diameter distribution. The materials showed good catalytic activity and high adsorption capacity for methylene blue.