【摘要】 采用回流法合成氧化锰八面体分子筛(OMS-2),并采用浸渍法负载Ce制备Ce-OMS-2催化剂,以分子氧为氧化剂考察了催化剂对苯甲醇液相氧化制苯甲醛的活性。当Ce含量为30%(质量分数)时,Ce-OMS-2催化剂的活性最高。100℃下反应1 h时,苯甲醇转化率为50.3%,催化剂的质量比活性达10.1 mmol.(g.h)-1。采用X射线衍射(XRD)、透射电镜(TEM)、X射线光电子能谱(XPS)、红外光谱(FT-IR)、程序升温还原(H2-TPR)对催化剂进行了表征。结果表明:所制备的催化剂具有结晶良好的八面体结构,当Ce含量小于30%时,Ce以高分散形式存在,但当Ce含量大于30%时,将出现聚集态CeO2结晶;高分散CeO2促进了OMS-2中MnOx的还原,改善了活性中心的电子传递,从而显著提高了催化剂活性。更多还原

【Abstract】 The manganese oxide octahedral molecular sieves(OMS-2) were synthesized by a reflux method.Ce-OMS-2 catalysts with different Ce loadings were prepared by the impregnation method.The catalytic performance of Ce-OMS-2 for the oxidation of benzyl alcohol to benzaldehyde with molecular oxygen in liquid-phase was studied.The catalytic activity of Ce-OMS-2 with a Ce-loading of 30%(mass fraction) was the highest,and the benzyl alcohol conversion was 50.3% with the mass specific activity of 10.1 mmol ·(g · h)-1 at 100 ℃ in 1 h.The XRD,TEM,XPS,FT-IR,and H2-TPR were used to characterize Ce-OMS-2 catalysts.The synthesized catalysts possessed good crystalline structure of octahedral molecular sieve.The highly dispersed CeO2 species could be obtained with a Ce-loading up to 30%,whereas large amount of Ce resulted in aggregated CeO2 crystalline clusters.The highly dispersed CeO2 species on OMS-2 played an important role in catalytic performance of the Ce-OMS-2 catalyst,promoting the reduction of MnOx,favoring the electrical transfer of active sites,and thus remarkably enhancing the catalytic activity.更多还原