Methane decomposition with a minimal catalyst: An optimization study with response surface methodology over Ni/SiO₂ nanocatalyst

Nowadays, methane cracking in the presence of an efficient catalyst is one of the most investigating areas aiming hydrogen and nanocarbon synthesis. This research contribution systematically investigated the influence of methane partial pressure (P_CH4), decomposition temperature, and weight of Ni/SiO₂ nanocatalyst (n-Ni/SiO₂) on carbon nanotube (CNT) yield. The optimum reaction condition for optimal methane cracking resulted in maximum CNT yield is derived using Design Expert Software. A series of experiments conducted to develop a quadratic polynomial model for CNT yield using response surface methodology. Surprisingly, the optimum catalyst quantity was the lowest (0.30 g) in the experimented parameter range, which exhibited the highest CNT production at 610 °C temperature and 0.8 atm P_CH4. The minimal catalyst quantity for the optimum CNT production, which needs only 0.26% of the total volume of the pilot plant reactor, is a breakthrough finding in methane cracking research. It could help to overcome the reactor blockage limitation issues of the process in large scale applications. Thanks to the uniquely supported n-Ni/SiO₂ catalyst prepared via co-precipitation cum modified Stöber method. The fresh and used catalysts investigated using different types of characterization techniques such as XRD, BET, Raman spectra, HRTEM, and FESEM-EDX. Characterization results evidenced the presence of differently structured CNTs formed at optimum reaction conditions.