Preparation and characterization of sno2 nanoparticles and sno2 supported nickel nanoparticles and the study of their catalytic activities on the hydrogenation of styrene

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Date
2007
Authors
Razana, Nur Ariesma
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Abstract
In this research, nanosize tin oxide, SnO2 was prepared using sol gel method by varying the reaction parameters such as ammonia concentration, ammonia feed rate, reaction temperature and calcination temperature. To study the effect of complexing agent, citric acid with different ratio of acid to tin was used. Tin oxide supported nickel, Ni/SnO2, were prepared using two different chemical reduction methods i.e.; impregnation and simultaneous reduction. Reactions were carried out using different experimental temperatures (70, 80, 90 and 100 oC), different nickel loadings (2.5, 5, 7.5 and 10 wt %) and different pH. The influences of these parameters on the particles size, particles distribution and surface area were investigated using Fourier Transform Infrared (FTIR), Transmission Electron Microscopy (TEM), Scanning Electron Microscope (SEM), Energy Dispersive X-ray Analysis (EDX), X-ray Diffraction (XRD) and Brunauer-Emmett-Teller (BET) Analysis. It was found that calcination temperature of 400 °C was needed to produce high purity tin oxide. The addition of higher concentration of ammonia led to a faster hydrolysis rate and condensation process thus, resulting in bigger tin oxide nanoparticles. In general, the particles size for SnO2 obtained were in the range of 4.0 ± 0.9 to 7.1 ± 2.4 nm. This study successfully produced SnO2 particles with larger surface area which is around 75 to 114 m2/g compared to the value reported in the literature. It was also observed that the slower ammonia feed rate produced small and well-distributed particles. However, a very slow feed rate (0.01 mL/min) led to bigger particle. Higher reaction temperature resulted smaller but highly aggregated tin oxide particles. The addition of citric acid resulted in good particles distribution, but larger particle size was observed. It was observed that the increase of reaction temperature led to bigger Ni/SnO2 particles in impregnation method, in contrast to the particles produced using simultaneous reduction method. Analysis showed that nickel was evenly distributed on the support in impregnation method while the latter method contains less evenly distributed particles. The catalytic activities of SnO2 and Ni/SnO2 were later investigated in the hydrogenation process of styrene. It was revealed that tin oxide prepared in high alkaline condition exhibited high catalytic activity. The conversion of styrene to ethyl benzene between 25 to 75 % was obtained depending on the preparation method and experimental parameters especially on pH and experimental temperature.
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Master
Keywords
Science Chemistry , sno2 nanoparticles , nickel nanoparticles , catalytic activities , hydrogenation , styrene
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