Читать книгу Carbon Nanofibers - Группа авторов - Страница 78

In the co-precipitation method, the metal catalysts with different compositions are prepared according to the ratio of the metal content required. Solution A was composed of aluminum nitrate, which helps to generate alumina (Al₂O₃) to serve as a supporter for the transition metal catalysts in the transition metal nitrate, dissolved in distilled water. The coagulation phenomenon occurs when the temperature is increased. To control the interparticle coagulation of transition metals, such as Fe, Co, and Ni, which all have catalytic activity against the reaction gas during high-temperature reaction, another Solution B, composed of ammonium molybdate and distilled water was added with Solution C made of ammonium carbonate, which serve as a precipitator to precipitate the transition metals and the aluminum included in Solution A. Precipitation was induced by gradual blending of the mixture composed of Solutions A and B and the mixture of Solution C. This step was followed by agitation for stability of the precipitation. These solutions were sufficiently stirred to stabilize the precipitates; moisture was removed by filtering; and they were dried for more than 12 h in a 110 °C oven. Fully dried precipitates were made into powder, and this powder of a metal catalyst was used as the catalyst in the synthesis of carbon nanofibers.