| Popis: |
Abstract Methane decomposition is a promising route to synthesize COx‐free hydrogen and carbon nanomaterials (CNMs). In this work, the impregnation method was employed for the preparation of the catalysts. Systematic investigations on the activity and stability of Fe‐based catalysts were carried out in a packed‐bed micro‐activity reactor at 800 °C with a feed gas flow rate of 18 mL/min. The effect of doping Y2O3, MgO, SiO2 and TiO2 over ZrO2 on the catalytic performance was also studied. BET revealed that the specific surface areas and pore volumes are increased after SiO2, TiO2, and Y2O3 are added to ZrO2 while MgO had a negative impact and hence a little decrease in specific surface area is observed. The catalytic activity results showed that the Fe‐based catalyst supported over TiO2‐doped ZrO2 that is, Fe−TiZr, demonstrated the highest activity and stability, with a maximum methane conversion of 81.3 % during 180 min time‐on‐stream. At 800 °C, a maximum initial methane conversion of 73 %, 38 %, 64 %, and 69 % and a final carbon yield of 121 wt. %, 55 wt. %, 354 wt. %, and 174 wt. % was achieved using Fe−MgZr, Fe−SiZr, Fe−TiZr and Fe−YZr catalysts, respectively. Moreover, bulk deposition of uniform carbon nanotubes with a high degree of graphitization and different diameters was observed over the catalysts. |
