Growth of carbon nanofibers from methane on a hydroxyapatite-supported nickel catalyst

Abstract

Carbon nanofibers (CNFs) were grown using catalytic chemical vapor deposition (CCVD) with methane as the carbon source and a hydroxyapatite-supported nickel catalyst (Ni/HAp). The catalyst, which contained approximately 14 wt% Ni, was prepared using the incipient wetness method with an aqueous nickel nitrate solution. Temperature-programmed reduction and X-ray diffraction were used to characterize the active phase of Ni/HAp. Three variables were evaluated to optimize the CNF growth process, including the temperature and the time of catalyst reduction as well as the reaction time, at 650°C. Regardless of the applied CCVD process conditions, herringbone bamboo-like CNFs were grown during methane decomposition over Ni/HAp, which was confirmed using transmission electron microscopy. A high CNF yield of nearly 10 g CNF g cat -1was achieved at 650°C after a reaction time of 3 h when the catalyst was subjected to a reduction at the same temperature for 2 h under a hydrogen flow prior to synthesis. As the reduction temperature increased from 450 to 650°C, both the yield and diameters of the CNFs increased. The beneficial effects of including hydrogen in the reaction mixture on the catalytic performance of Ni/ HAp and the purity of the grown CNFs were demonstrated.

Propanol Amination over Supported Nickel Catalysts: Reaction Mechanism and Role of the Support

“…The large reduction peak at 590 K corresponds to the reduction of bulk NiO species, while the shoulder peak at 490 K is due to the reduction of very small NiO particles. 24 The high-temperature peak at 750 K is indicative of the reduction of isolated Ni 2+ species stabilized by the HAP framework, likely as a result of the substitution of two protons or Ca 2+ in HAP by Ni 2+ . 25 Propanol Amination over Supported Ni Catalysts.…”

Infiltrate Mesoporous Silica-Aluminosilicate Structure Improves Hydrogen Production via Methane Decomposition over a Nickel-Based Catalyst

“…Two distinct temperature rangesbelow 100 °C and one above 400 °Cclearly emerge in the weight loss curve of each of the Ni/SAS­( x ) and Ni/MCM-41 catalysts. Weight loss below 100 °C corresponded to the moisture removal on the catalyst, whereas the second weight loss in the temperature range of 450–800 °C is attributable to the decomposition of carbon nanotubes (CNTs). , The carbon products of Ni/SAS­( x ) and Ni/MCM-41 catalysts formed through the CH 4 decomposition reaction at 500, 550, and 600 °C calculated in terms of the relative carbon yield are shown in Table . It was found that the relative carbon yield of Ni/SAS(50) and Ni/SAS(100) catalysts increased with an increasing reaction temperature, whereas the relative carbon yield of Ni/SAS(25) and Ni/MCM-41 catalysts increased only when the reaction temperature was increased from 500 to 550 °C but decreased when the temperature was increased again to 600 °C.…”

The Production of Carbon Nanofiber on Rubber Fruit Shell-Derived Activated Carbon by Chemical Activation and Hydrothermal Process with Low Temperature

“…As a result, CNFs involve three main components: gases, an underlayer, and a catalyst. It is well known that the transition metals Fe, Ni, and Co have been used as a catalyst for CNF synthesis and significantly impact the morphology and performance of CNFs [ 55 ]. It is also known that biomass materials as activated carbon precursors can act as catalysts in the synthesis of carbon nanomaterials since some mineral elements are widespread in biomass matrices as essential trace elements for plant growth.…”