CAJ | 학술논문

以柠檬酸燃烧法制备的Ni/MgO,Ni/CeO2-MgO和Ni/CeO2为催化剂,CH4为碳源,采用化学气相沉积法制备多壁碳纳米管(MWCNTs),通过N2吸附、X射线衍射、H2程序升温还原和X射线光电子能谱对催化剂进行表征,并运用热重和透射电镜表征了碳纳米管的质量和形貌.结果表明,CeO2的加入可有效地降低还原温度和增加易还原Ni物种的含量,并使电子发生转移,还原后的Ni/CeO2-MgO催化剂中,Ni晶粒尺寸较小.这表明CeO2的加入使得Ni物种的化学环境发生改变,导致它和载体间的相互作用减弱,从而促进Ni物种的还原,且还原后,高度分散在CeO2-MgO载体上,从而催化剂的催化活性增加.相比Ni/MgO催化剂,Ni/CeO2-MgO为催化剂上生长的CNTs质量更高.另外,由CeO2助Ni/MgO催化剂制备出基本没有无定形碳、结晶度好的碳纳米管.
이저몽산연소법제비적Ni/MgO,Ni/CeO2-MgO화Ni/CeO2위최화제,CH4위탄원,채용화학기상침적법제비다벽탄납미관(MWCNTs),통과N2흡부、X사선연사、H2정서승온환원화X사선광전자능보대최화제진행표정,병운용열중화투사전경표정료탄납미관적질량화형모.결과표명,CeO2적가입가유효지강저환원온도화증가역환원Ni물충적함량,병사전자발생전이,환원후적Ni/CeO2-MgO최화제중,Ni정립척촌교소.저표명CeO2적가입사득Ni물충적화학배경발생개변,도치타화재체간적상호작용감약,종이촉진Ni물충적환원,차환원후,고도분산재CeO2-MgO재체상,종이최화제적최화활성증가.상비Ni/MgO최화제,Ni/CeO2-MgO위최화제상생장적CNTs질량경고.령외,유CeO2조Ni/MgO최화제제비출기본몰유무정형탄、결정도호적탄납미관.
Ni/MgO,Ni/CeO2-MgO,and Ni/CeO2 catalysts were prepared by the citric acid combustion method.Their catalytic properties forthe synthesis of multi-walled carbon nanombes (MWCNTs) by chemical vapor deposition using CH4 as carbon source were evaluated.The catalysts were characterized with N2 adsorption,X-ray diffraction (XRD),H2 temperature-programmed reduction (H2-TPR),and X-ray photoelectron spectroscopy (XPS).The quality and structure of the CNTs were characterized by thermogravimetry (TG) and transmission electron microscopy (TEM).H2-TPR showed that CeO2 helped decrease the reduction temperature and increase the content of an easily reducible Ni species.XPS showed an energy shift of the Ni catalyst that was modified by CeO2.XRD showed that the reduced nickel maintained their small particle sizes in the Ni/CeO2-MgO catalysts.These findings suggested that the addition of CeO2 changed the chemical environment of the nickel species,which resulted in a weaker interaction between the nickel and the support and increased the reducibility of the Ni species.Moreover,the reduced nickel was highly dispersed on the CeO2-MgO support.The change enhanced the catalytic activity for the growth of carbon nanotubes (CNTs).Characterization by TG and TEM showed that the quality of the CNTs grown on Ni/CeO2-MgO was better than those grown on Ni/MgO catalyst.