A simple synthesis method to obtain Ni/carbon catalysis for CNT production

AGUSTÍN E. GALETTI; LUIS A. ARRUA; MARIA CRISTINA ABELLO

Cancún

Congreso; XXI International Materials Research Congress; 2012

Sociedad Mexicana de Materiales

A simple catalyst for carbon nanotubes (CNT) production from ethanol steam reforming is presented. The catalyst is based on high dispersed nickel particles over carbon, produced from thermal decomposition of cellulosic paper impregnated with a nickel solution. Cellulosic paper discs were immersed in an aqueous nickel solution for 30s. Wet discs were dried at 80°C before being placed in a fixed bed reactor and calcined at 500, 600 or 700°C under 300 mL min-1 of 5%H2/N2 at 42°Cmin-1 for 30min. The samples with 7%wt of Ni were identified as N7C500, N7C600 and N7C700, respectively. Analogous Ni free samples were named C500, C600 y C700. Characterization was performed by X-ray diffraction (XRD), superficial area (SBET) and scanning electron microscopy (SEM). Catalytic tests were carried out under ethanol steam reforming conditions [1-2]. High-surface-areas (SBET=300-445m2g-1) were achieved being the highest for the sample calcined at 600°C. SBET of N7C500 was markedly higher than C500 due to the Ni presence favored the organic matrix decomposition at this temperature. XRD patterns of fresh samples confirmed the Ni0 presence. Ni nanoparticles between 5-9nm were obtained. After used XRD of samples revealed Ni sintering (dNi=28nm) and the presence of graphitic carbon suggesting structural changes in carbonaceous phase. SEM images of fresh samples shown hollow and not hollow carbon fibers with diameters among 9-13µm could be distinguished. Internal and external surfaces of the fibers seem to be rough. SEM images of used catalysts revealed the formation of carbon nanofibers and carbon nanotubes. Its amount increased with the sample calcination temperature. The main gaseous reaction products were H2, CO2 and CO. The proposed synthesis method allowed to obtain, in a simple and low-cost way, Ni catalysts supported on carbon for carbon nanotubes production. Carbon nanotubes could be easily isolated and purified from catalysts.