The effect of copper catalyst reducibility on low temperature carbon fiber synthesis

A temperature programmed reduction (TPR) investigation of copper supported catalysts was undertaken to establish the role of reduction temperature on copper and its effect on the synthesis of shaped carbonaceous material (spiral, straight or formless carbon nanofibers) produced by the CCVD method. Catalyst reducibility was found to be strongly related to the type of support used (TiO2 < MgO < CaO), the copper precursor (Cu(NO3)2 < CuCl2 < Cu(acac)2) and to a lesser extent solvent utilized. The most favorable yields of carbon fibers were obtained by reducing catalysts at temperatures inferred from TPR data. The reduction temperatures used impacted upon the morphology of the carbon fibers produced (straight, spiral or curled). We have found that carbon fibers synthesized from copper catalysts at low temperature (250 °C) utilizing Cu(NO3)2/TiO2/water gave the best mass yield (340%) and selectivity towards carbon material with helical morphology (70%).