CO2活化对聚硅氧烷裂解SiC衍生炭孔结构的影响

Effect of the CO2 activation parameters on the pore structure of silicon carbide-derived carbons

    摘要
  • 摘要: 经聚硅氧烷裂解转化得到碳化硅粉体，然后对其进行氯化处理得到炭，再通过CO2活化处理得到具有高比表面积（1 316.8~1 929.0 m2·g-1）的微孔炭（SiC-DC）材料。研究了CO2活化温度、时间对SiC衍生多孔炭结构的影响。采用氮气吸附法、X-ray衍射光谱（XRD）、扫描电镜（SEM）及透射电镜（TEM）等技术对SiC-DC样品微观结构随活化温度、时间演变进行表征分析。结果表明，CO2活化处理可以有效调控SiC-DC的孔结构，而对其结晶性影响很小，且活化处理后样品保持着SiC粉体或未活化SiC-DC样品的原有形态和微观结构（如石墨带）。对于已活化SiC-DC样品，比表面积（SSA）、总孔容（Vtot）及微孔孔容都随活化温度、时间增加而增加，但同时活化产率逐渐降低。相比未活化样品，SiC-DC在950℃条件下活化处理2 h后，SSA和Vtot值分别增加了46.5%、86.4%，主要原因是经活化处理，微孔孔容明显增加。

     

    Abstract: A silicon carbide derived carbon (SiC-DC) with a high specific surface area (SSA) fabricated by chlorination of a silicon carbide derived from polysiloxane was activated by CO2. The effect of activation temperature and time on the microstructure of the activated samples was investigated by N2 sorption, XRD, SEM and TEM. Results showed that CO2 activation effectively changed the pore structure of the SiC-DC and had little impact on carbon crystallinity. The activated samples retained the morphology of the SiC powder or the non-activated SiC-DC. The SSA, total pore volume (Vtot) and micropore volume of the activated SiC-DCs all increased and the yield decreased with increasing activation temperature or time. The SSA and Vtot increased by 46.5% (from 1 316.8 to 1 929.0 m2·g-1) and 86.4% (from 0.560 to 1.044 cm3·g-1), respectively after the SiC-DC was activated at 950℃ for 2 h, mainly as a result of the increased micropore volume.

     

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