采用化学氧化法，以粒径为180 μm的天然鳞片石墨为原料，在混酸（乙酸酐-磷酸-高氯酸）混合固体助氧化剂（高锰酸钾-重铬酸钾）体系下制得无硫可膨胀石墨。确定最佳合成条件为：m（鳞片石墨）∶V（混酸）∶m（高锰酸钾）∶m（重铬酸钾）=1（g）∶4（mL）∶0.1（g）∶0.1（g），50 ℃反应60 min，40 ℃干燥2 h。在此条件下得到初始膨胀温度为 200 ℃的无硫可膨胀石墨，在500 ℃下的最大膨胀体积高达665 mL/g。通过SEM、FT-IR、XRD及TGA测试对鳞片石墨、可膨胀石墨和膨胀石墨进行结构、形貌、官能团分析。结果表明：可膨胀石墨片层间距增大，成功插入高氯酸、磷酸、乙酸酐；且经膨化后，得到纯度较高、孔隙较发达且片层晶体结构未改变的无硫高膨胀体积膨胀石墨。

By using nature flake graphite of 180 μm as raw material，sulfurfree expandable graphite was synthesized via che mical oxidation method in the mixed acid（acetic anhydride phosphoric acid perchloric acid） and mixed solid assistant oxi dant（potassium permanganatepotassium dichromate） system.The optimum preparing conditions were as follows：m（flake graphite）∶V（mixed acid）∶m（potassium permanganate）∶m（potassium dichromate）=1（g）∶4（mL）∶0.1（g）∶0.1（g），reacted at 50 ℃ for 60 min and dried at 40 ℃ for 2 h.Under these conditions，the sulfurfree expandable graphite with an initial expansion temperature of 200 ℃ was obtained，meanwhile the maximum expanded volume of which could reach up to 665 mL/g when exfoliated at 500 ℃.The structure，morphology and functional groups of flake graphite，expandable graphite and expanded graphite were characterized by SEM，FT-IR，XRD and TGA.Results showed that perchloric acid，phosphoric acid and acetic anhydride successfully inserted into the graphite layers as a result of the expansion of interlaminar spacing of expandable graphite，and after puffing，sulfurfree expanded graphite was obtained，which had large expanded volume，high purity，rich space structure and the same slice layer crystal structure as flake graphite.