Effect of H3PW12O40 impregnation on Sn-MCM-41 mesoporous molecular sieves and their physico-chemical properties

• To enhance the total acidity of Sn-MCM-41 TPA is impregnated.
• FT-IR and 31P MAS NMR confirms the HPWA intact on Sn-MCM-41.
• EDAX shows the presence of W and P on Sn-MCM-41.
• In ODS formation of sulfone was confirmed by FT-IR and 1H NMR.
• The order of the catalytic activity of the catalysts are 18HSnM > 28HSnM > 8HSnM.

Si-Sn-MCM-41 (Si/Sn = 110) mesoporous molecular sieve was synthesized by hydrothermal sol–gel method using cetyltrimethylammonium bromide (CTAB) as surfactant and SnCl4·5H2O as a metal source. To generate surface acidity of Si-Sn-MCM-41, 12-tungstophosphoric acid (HPWA) is impregnated on it. The acidity of HPWA loading on Sn-MCM-41 was investigated by temperature programmed desorption of NH3. The diffused reflectance spectra of ultraviolet radiation, Raman spectra, FT-IR, 29Si-MAS NMR and 31P-MAS NMR techniques revealed the intact of α-Keggin anions on Sn-MCM-41. The wide angle XRD results showed that the HPWA is well dispersed on the support. The total acidity was enhanced with increase in loading of H3PW12O40. The catalytic activity was examined in desulfurization of dibenzothiophene in vapor phase system. Among the catalysts 18% HPWA loaded Sn-MCM-41 showed good catalytic activity in desulfurization at 325 °C. The HPWA/Sn-MCM-41 are a suitable solid acid catalyst for converting organic sulfur into insoluble sulfone.

The wide angle XRD shows the well dispersion of HPWA in Sn-MCM-41. It enhances the total acidity of the material. The acidity of the material is correlated with sulfone selectivity. The FT-IR of dibenzothiophene and product shows the formation of sulfone (DBTO2).Figure optionsDownload as PowerPoint slide