催化热解C_2H_2制备螺旋形碳晶须

Preparation of Coiled Carbon Whiskers by the Catalytic Pyrolysis of Acetylene

以Ni粉为催化剂,在高温下催化热解乙炔(C2H2),制备出了螺旋形碳晶须材料.实验结果表明:催化热解乙炔(C2H2)制备螺旋形碳晶须的最佳温度范围为450～600℃,恒温时间为60～70min,气体流量比分别为ρ(C2H2)∶ρ(Ar)=7∶6,ρ(C2H2)∶ρ(Ar)=25∶3及ρ(C2H2)∶ρ(Ar)∶ρ(H2)=3∶4∶7.经透射电镜、扫描电镜、X射线衍射仪分析表明,螺旋形碳晶须的螺径为130～1000nm,螺距为100～350nm,晶须直径在100nm左右,晶须长度达几百微米.在加入氢气的情况下,出现了少量的直径在500nm左右的管状碳晶须.将螺旋形碳晶须放入Ar气中,850℃温度下经历1h,成分结构未变,结晶性更好.

Coiled carbon whiskers were prepared by the catalytic pyrolysis using acetylene as a carbon source and Ni catalyst at high temperature. The growth conditions of the coiled carbon whiskers were examined. The results show that the best catalytic pyrolysis temperature for preparing coiled carbon whiskers is 450-600 ℃, and the preparing time is 60-70 min. The proportion of gases is ρ(C_2H_2)∶ρ(Ar)=7∶6,(ρ(C_2H_2)∶)ρ(Ar)=25∶3 and ρ(C_2H_2)∶ρ(Ar)∶ρ(H_2)=3∶4∶7 respectively. Analyzed by XRD, SEM and TEM, it shows that the coiled carbon whiskers are 130-1 000 nm in coil diameter, 100-350 nm in coil pitch, about 100 nm in diameter and several hundreds mm in length. By adding H_2 gas, a few tube\|shaped carbon whiskers having 500 nm coil diameter were obtained. The ingredients and structure of the coiled carbon whiskers remain unchanged after putting in 850 ℃ Ar gas for 1 hour, even with its crystalizability improved.