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.
Description
Master
Keywords
Science Chemistry , sno2 nanoparticles , nickel nanoparticles , catalytic activities , hydrogenation , styrene