The Bimetallic Effects of Catalysts on the Syntheses of Thin Carbon Nanofibers

Abstract

Thin carbon nanofibers with less than 100 nm diameter were variously prepared over MgO-supported nickel and bimetallic nickel catalysts with iron, copper, and molybdenum. The second metal effects on the carbon yield and structure were investigated by using electron microscopic and gas chromatographic methods. Further, the active catalysts were examined by powdered X-ray diffraction to elucidate correlation between the catalyst and nanofiber growth. The surface composition of catalysts appeared to govern the catalyst activity and the resulting CNF structure. The second metal effects on the catalyst activity and resulting nanofiber structure is discussed in terms of the formation mechanism of carbon nanofibers, on the basis of the results.

Direct Synthesis and Structural Analysis of Nitrogen-Doped Carbon Nanofibers

“…In a previous study, thin CNFs have been successfully synthesized from an ethylene/hydrogen mixture over a bimetallic nickel−iron catalyst supported on MgO . Figure shows SEM and TEM images of CNFs synthesized from ethylene/hydrogen 1/1 (v/v) at 530 °C over NiFeMgO.…”

“…In a previous study, thin CNFs with less than 100 nm diameter were successfully prepared over a MgO supported nickel−iron catalyst, which was used as the catalyst for preparation of N-doped CNFs in this study. The catalyst was prepared following the procedure used by Chen et al and Pang et al Magnesium nitrate and catalyst precursor salts of corresponding metals were completely dissolved in distilled water, and then a prescribed amount of citric acid was added to the aqueous solution. The solution was boiled to evaporate water until the liquid became pasty and some part turned into an incandescent solid.…”

“…Synthesis of CNFs was based on the method used by Pang et al, except for introducing the nitrogen source chemicals by vapor. CNFs were synthesized in a fixed-bed reactor (quartz tube of 5 cm ϕ × 80 cm equipped in a horizontal electrical furnace).…”

“…In this study, CNFs containing nitrogen in the structure were synthesized directly from acetonitrile or acrylonitrile vapors over MgO-supported nickel−iron catalysts at low temperatures of 400−600 °C, with the purpose of exploring advanced surface functions and new structural properties of CNFs. The synthetic route was based on preparation of herringbone CNF with 30 nm diameter . The focus of this study was put on control of the nitrogen content, CNF growth rate, and the chemical state of nitrogen in CNFs, as well as the structural change of CNF by N-doping.…”

Formation and catalytic performance of supported ni nanoparticles via self‐reduction of hybrid NiAl‐LDH/C composites

“…Although the supported catalysts may be fragmented by the mechanical stress in the fluidized‐bed reactor, the resulting subagglomerates of catalysts can expand into large agglomerates combined with CNTs formed in the CCVD process 28. On the other side, the synthesis parameters for catalysts, such as compositions, loading amounts, and loading ways of catalysts have significant effects on the microstructures and the shapes of obtained carbon nanostructures 29–31. Recently, the catalytic growth of carbon nanostructures has been achieved using LDH‐derived catalysts via CCVD 32–38.…”