Avaliação cinética da síntese de carbeto de tungstênio (WC) via reação gás-sólido entre paratungstato de amônio (APT) e a mistura gasosa CH4-H2 em reator de leito fixo
The application of tungsten carbide (WC) stands out in the mechanical, chemical and aerospace industries for presenting a unique combination of properties, such as high hardness, high melting point, high wear resistance, great chemical and thermal stability. Traditionally, its production occurs v...
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| Formato: | bachelorThesis |
| Idioma: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/39574 |
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| Resumo: | The application of tungsten carbide (WC) stands out in the mechanical,
chemical and aerospace industries for presenting a unique combination of properties,
such as high hardness, high melting point, high wear resistance, great chemical and
thermal stability. Traditionally, its production occurs via a carburization reaction
between a tungsten source and a carbon source at high temperatures (1400°C and
1800°C) and long reaction time. Several WC synthesis methods have been
investigated in order to obtain powders with high purity and high surface area, and to
optimize processing. The Department of Chemical Engineering at UFRN (DEQ)
developed a synthesis route via gas-solid reaction between ammonium paratungstate
(APT) and the CH4-H2 mixture capable of producing pure tungsten carbide after one
hour of reaction at a temperature of 850 °C in a fixed bed reactor. Various processing
conditions were studied, but kinetic data analysis was not performed. This type of
analysis is a fundamental step in evaluating the feasibility of implementing the
synthesis process on a large scale. Thus, the present work aims to carry out a kinetic
evaluation of the WC synthesis developed by DEQ from methane conversion data
available in the literature. The synthesis data were obtained using the "Digitalize" tool
of the Origin® software, and modeled to verify which kinetic model best fits the
reaction: the Power Law Model (first order reaction) or the Avrami Model. The results
indicate that the 1st order model fits the analyzed experimental data (R2 > 0.90). Kinetic
constant of k= 0.0017 min-1 with R² = 0.935 was determined for synthesis reactions at
T=850°C, Q=17L/h and 1 hour of isotherm. |
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