Highly selective synthesis of trans-stilbene oxide over mesoporous Mn-MCM-41 and Zr–Mn-MCM-41 molecular sieves

Abstract

trans-Stilbene oxide have been synthesized under liquid phase reaction conditions using trans-stilbene in the presence of different oxidants and different solvents over synthesized and characterized Zr–Mn-MCM-41 and Mn-MCM-41 as catalysts. On increasing the Si/(Zr + Mn) ratios of Zr–Mn-MCM-41 and Si/Mn ratios of Mn-MCM-41 catalysts from 49 to 327 and 15 to 102, respectively, the conversion of trans-stilbene, yield and selectivity of trans-stilbene oxide decreased. This may be due to the number of Lewis acid sites in Zr–Mn-MCM-41 and Mn-MCM-41 are found to decrease almost linearly with increasing ratios of Si/(Zr + Mn) and Si/Mn, respectively. Both the Zr–Mn-MCM-41(49) and Mn-MCM-41(31) possesses stronger affinity with trans-stilbene and TBHP, but, the conversion of trans-stilbene, yield and selectivity of trans-stilbene oxide decreased in only recyclable Mn-MCM-41. This may be due to decreasing the catalytic activity on the surface of catalysts. In the context, the Si/(Zr + Mn) ratio of 49 is found to be more suitable for the epoxidation of trans-stilbene to highly selective synthesis of trans-stilbene oxide. Thus the yield (76.3%) and selectivity of trans-stilbene oxide (84.58%) are higher in Zr–Mn-MCM-41(49) than that in other Zr–Mn-MCM-41 and Mn-MCM-41 catalysts.