Study On The Preparation Of Carbon Nanotubes And The Catalytic Properties Over CNTs Supported NiB Amorphous Alloy Catalyst

Carbon nanotubes(CNTs) were prepared by catalytic chemical vapor deposition(CCVD) and poros aluminium anodic oxidation templates(PAAO). The effect of preparation condition of catalyst, reaction condition and La content on the growth of CNTs was investigated. Some characteristics of catalysts and CNTs were investigated by XRD, TEM, SEM, BET, XPS. CNTs were purified and opened by HNO3 oxidation. CNTs supported amorphous NiB alloy were prepared by chemical reduction combined with impregnation. Benzene hydrogenation by pulse was used as a probe reaction for the study of effect of pre-treatment to CNTs, nickel salt concentration and supports on the catalytic properties. Catalysts were characterized by XRD, ICP, TEM, SEM, BET, DSC, H2-TPD, TPR, XPS. Experimental results showed that as catalysts precursor were prepared by citric acid method, the concentration of citric acid and the activation temperature would affect the structure of catalysts and the size of catalyst particles, the growth of CNTs were affected afterwards. The reaction conditions played important role in preparation of CNTs. The addition of La in catalysts could make the CNTs thinner, improve the crystallinity and thermal stability of CNTs. The purity of pieces of aluminum affected the properties of aluminum oxide membrane. The aluminum oxide membrane had the function of template only after the nickel were impregnated on the aluminum oxide membrane by alternating current sediment. The control of reaction condition was important when CNTs were purified and opened by HNO3 oxidation. As the support of amorphous NiB alloy, CNTs being opened and thermal pretreated under 373K were good to catalytic activity of hydrogenation. Because opening made the surface of CNTs be fully utilized and thermal pretreatment at low temperature could make the surface oxygen groups on CNTs not be destroyed, so the nickel could be supported on CNTs more effectively; CNTs acted as electronic catalyst-accelerator in catalyst, partial electron transferred from CNTs to metal nickel made Ni electron-rich and improved the catalytic activity of NiB/CNTs; The amorphous alloy particles were hindered to gather due to the unique central-hollow structure of CNTs. It made catalysts maintain the amorphous structure at higher temperature and improved the thermal stability of NiB/CNTs; The strong adsorptive-ability to CS2 of CNTs made the sulfer-resistance ability of NiB/CNTs worse; The chemical inertness of surface and the ability of losing electron of CNTs made amorphous NiB/CNTs be reducted easily; The higher hydrogen-storage ability of CNTs built high concentration hydrogen-atmosphere in the process of hydrogenation, it improved the catalytic activity.