Heteropolyoxometalate which are included in microporous silica,Cs_xH_(3-x)PMo_(12)O_(40)/SiO_2 and Cs_yH_(5-Y)PMo_(10) V_2o_(40)/SiO_2,as insoluble solid bifunctional catalysts:synthesis and selective oxidation of benzyl alcoholin liquid-solid systems

摘要

Heteropolyoxometalates (HPOMs) which are included in microporous silica,Cs_xH_(3-x)PMo_(12)O_(40)/SiO_2 and Cs_yH_(5-y)PMo_(10)V_2O_(40)/SiO_2,have been synthesized by a sol-gel technique and characterized by IR,UV-VIS,X-ray and N-2 adsorption isotherms.IR and UV-VIS data indicate that the identities of Cs_xH_(3-x)PMo_(12)O_(40) and Cs_yH-(5-y)PMo_(10)V_2O_(40) are preserved within these synthesized compounds.TEM image and BET adsorption isotherms confirm the presence of nanometer particles and microporous structures.X-ray powder patterns prove that the cesium salts of the HPOMs are uniformly dispersed in the silica network.As insoluble solid bifunctional catalysts,they show high catalytic activity and selectivity for selective oxidation of benzyl alcoholinto benzyl aldehyde by H_2O_2 in liquid-solid systems.The highest activity is observed at x=1.5 or y=2.5 in Cs_xH_(3-x)PMo_(12)O_(40)/SiO_2 or Cs_yH_(5-y)PMo_(10)V_2O_(40)/SiO_2,respectively.