Study of carbon micro-coils prepared by a vapor phase catalytic cracking process

Carbon micro-coils were prepared by. a vapor phase catalytic cracking (VCC) process, using commercial acetylene as the carbon source, a nickel plate as catalyst and a sulfur compound as impurity. Reaction conditions which affected the growth of carbon micro-coils were investigated. The nickel plate was located in the center of quartz tube with carbon micro-coils growing on both sides. The carbon yield for the nickel plate is higher than that for nickel powder. The optimum reaction conditions for carbon micro-coil formation were as follows: reaction temperature 710 degreesC 800 degreesC, the ratio of C2H2, to H-2 1: 3, the flow rate of impurity 1.0 mL/min similar to 1.2 mL/min. Carbon micro-coils with different coil diameters were obtained by regulating the N-2 flow rate. Carbon micro-coils with coil diameter about 4 rim and about 20 rim were obtained with total gas flow rates of 150 mL/min and 200 mL/min respectively. The microstructures of the carbon micro-coils were examined by SEM. It was found that most of carbon micro-coils were double helical forms with villiform tips composed of curved nanofibers.