无硫高倍膨胀石墨的制备及影响因素探讨

Preparation of sulfur-free highly expanded graphite

以鳞片石墨、硝酸、乙酸酐、高锰酸钾为原料,采用化学法经氧化酸化插层、水洗、干燥、高温膨胀过程制备膨胀石墨,利用正交试验方法确定最佳工艺条件,并对相关影响因素及插层机理作了初步探讨。结果表明:按鳞片石墨∶硝酸∶乙酸酐∶高锰酸钾(质量比)=1∶0.7∶1.5∶0.4,反应时间90min,反应温度30℃～40℃的条件可以制备出膨胀体积达478mL/g的高倍无硫膨胀石墨。相关影响因素的大小依次为:高锰酸钾、硝酸、乙酸酐、反应时间,其中高锰酸钾的影响程度远大于其他三个因素。

Expanded graphite was prepared by a chemical method using natural flake graphite, concentrated nitric acid and acetic anhydride as intercalation agent, and potassium permanganate as oxidant. The conditions for preparing the expanded graphite was optimized by an orthogonal test method and factors affecting expanded volume and intercalation mechanism were obtained. Results showed that sulfur-free and expanded graphite of 478mL/g could be produced under the optimum conditions with the weight ratio of natural flake graphite: nitric acid: acetic anhydride: potassium permanganate being 1:0.7:1.5:0.4, reaction time of 90 min, and reaction temperature 30-40 degreesC. The descending order of affecting factors is KMnO4, nitric acid, acetic anhydride and reaction time.