CAJ | 학술논문

以SBA-15、六角介孔二氧化硅(HMS)和SnO2为载体,通过浸渍法合成了含钨负载型催化剂,并考察了三种催化剂在环氧环己烷选择氧化制备己二酸反应中的催化性能。通过X射线衍射(XRD),透射电镜/场发射透射电镜(TEM/FETEM),紫外-可见漫反射光谱(UV-Vis DRS),拉曼(Raman)光谱, X射线光电子能谱(XPS)以及傅里叶变换红外(FTIR)光谱等手段对各种催化剂的结构进行表征。结果表明,载体与催化剂的性能有密切的关系。以SnO2为载体的WO3/SnO2催化剂活性最高,其次是WO3/HMS催化剂, WO3/SBA-15催化剂的活性最差。 XRD分析显示WO3/SnO2催化剂中氧化钨物种的晶化程度最低, TEM和XPS结果表明氧化钨物种在WO3/SnO2催化剂表面高度分散并且粒径尺寸很小(约2 nm), UV-Vis DRS结果表明在WO3/SnO2催化剂中存在孤立[WO4]四面体和低聚态的钨物种,这些物种的存在可能是WO3/SnO2催化剂具有高活性的主要原因。此外, WO3/SnO2催化剂可以重复使用多次,6次反应后己二酸(AA)得率仍然保持在80%以上,说明氧化钨物种与SnO2载体间存在强烈的相互作用,从而提高了催化剂的稳定性。
이SBA-15、륙각개공이양화규(HMS)화SnO2위재체,통과침지법합성료함오부재형최화제,병고찰료삼충최화제재배양배기완선택양화제비기이산반응중적최화성능。통과X사선연사(XRD),투사전경/장발사투사전경(TEM/FETEM),자외-가견만반사광보(UV-Vis DRS),랍만(Raman)광보, X사선광전자능보(XPS)이급부리협변환홍외(FTIR)광보등수단대각충최화제적결구진행표정。결과표명,재체여최화제적성능유밀절적관계。이SnO2위재체적WO3/SnO2최화제활성최고,기차시WO3/HMS최화제, WO3/SBA-15최화제적활성최차。 XRD분석현시WO3/SnO2최화제중양화오물충적정화정도최저, TEM화XPS결과표명양화오물충재WO3/SnO2최화제표면고도분산병차립경척촌흔소(약2 nm), UV-Vis DRS결과표명재WO3/SnO2최화제중존재고립[WO4]사면체화저취태적오물충,저사물충적존재가능시WO3/SnO2최화제구유고활성적주요원인。차외, WO3/SnO2최화제가이중복사용다차,6차반응후기이산(AA)득솔잉연보지재80%이상,설명양화오물충여SnO2재체간존재강렬적상호작용,종이제고료최화제적은정성。
A series of tungsten-based catalysts were synthesized via a traditional impregnation method using SBA-15, hexagonal mesoporous silica (HMS), and SnO2 as the support. The supported catalysts were characterized by X-ray powder diffraction (XRD), transmission electron microscopy/field-emission transmission electron microscopy (TEM/FETEM), UV-Vis diffuse reflection spectroscopy (UV-Vis DRS), Raman spectrometry, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. It was found that the support was crucial to the dispersion and nature of the tungsten species on the catalyst. In this study, the catalytic performances of catalysts with different supports were investigated for the synthesis of adipic acid (AA) from the selective oxidation of cyclohexene oxide. The excellent catalytic performance of the catalyst was obtained over WO3/SnO2, followed by WO3/HMS and WO3/SBA-15. The XRD results indicate that the degree of crystallinity of the tungsten species of WO3/SnO2 catalyst was low and the particle size of WO3 was small (~2 nm). TEM and XPS results imply a high dispersion of tungsten species on the SnO2 support. The UV-Vis DRS spectra demonstrate the existence of [WO4] and low-polymeric tungsten species. In addition, the W-based catalyst with SnO2 as the support could retain high activity, even after being reused six times, suggesting that there is strong interaction between tungsten species and the SnO2-support that enhanced the stability of the catalyst. This shows the potential of the WO3/SnO2 as a catalyst for the synthesis of adipic acid.