Synthesis and Catalytic Application of Mesoporous Molecular Sieves MCM-41 Containing Niobium and Tantalum
Niobium- and tantalum-containing mesoporous molecular sieves MCM-41 have been synthesized, and applied as a catalyst for vapor phase Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam. NbMCM-41 catalyst exhibited high catalytic performance in the vapor phase Beckmann rearrangement of cyclohexanone oxime. The oxime conversions were almost 100% and the lactam selectivities were around 80%. The lactam selectivities of NbMCM-41 catalyst were higher than those of AlMCM-41 catalyst. However, TaMCM-41 catalyst exhibited lower catalytic performance than AlMCM-41 catalyst, and it was fast deactivated with time. These results may be due to the acidity difference among the catalysts. The results from NH3-TPD showed that NbMCM-41 catalyst possessed weak and medium acid sites, while TaMCM-41 catalyst possessed only very weak acid sites. AlMCM-41 catalyst also exhibited only weak acid sites.
Byung Tae Ahn, Hyeongtag Jeon, Bo Young Hur, Kibae Kim and Jong Wan Park
H. Jung et al., "Synthesis and Catalytic Application of Mesoporous Molecular Sieves MCM-41 Containing Niobium and Tantalum", Solid State Phenomena, Vols. 124-126, pp. 1761-1764, 2007