Catalytic decomposition of methane over Fe2O3-Al2O3 catalysts with high iron contents and at high CH4 space velocities

1. Five Fe 2 O 3 -Al 2 O 3 catalysts with 50-90% iron oxide were prepared for methane decomposition. 2. Catalytic tests were conducted at high CH 4 space velocities from 7500 to 30000 ml/h/g-cat. 3. Temperature and CH 4 velocity are two influential parameters of dominating CNFs productivity. 4. 80% Fe 2 O 3 -Al 2 O 3 catalyst enables production of CNFs with a purity of >95%. 5. CNFs are highly electric-conductive for formulation of anti-static CNFs-reinforced plastics. Catalysts Fe 2 O 3 -Al 2 O 3 with high Fe 2 O 3 contents (50-90wt%) were prepared by co-precipitation method and tested for methane decomposition and production of high-purity carbon nanofibers (CNFs). Catalytic tests were conducted in a fixed-bed reactor at atmospheric pressure, different temperatures and high CH 4 space velocities. The catalytic tests performed at 700 °C showed that Fe 2 O 3 -Al 2 O 3 catalysts containing 60-80wt% Fe 2 O 3 enable a maximal CH 4 conversion of around 56% and production of CNFs with a purity above 95%. Further, the catalytic results recorded over 80% Fe 2 O 3 -Al 2 O 3 catalyst at varied temperatures and space velocities revealed the following: (1) increasing temperature leads to an increased maximum CH 4 conversion but a reduced CNFs productivity per unit weight of catalyst, and (2) CNFs productivity can be maximized at each temperature by lowering CH 4 space velocity to an appropriate rate through reducing CH 4 feed rate or increasing the amount of catalyst fed in the reactor. Moreover, typical SEM, Raman and TEM characterization results confirmed that the CNFs obtained are of a relatively narrow diameter distribution of 20-40 nm and graphitic nanostructure in appearance. Furthermore, electroconductivity measurement of typical CNFs products confirmed their good electrical conductivity, suggesting their potential direct use for formulation of anti-static CNFs reinforced plastic composites.