煤基多级孔炭纳米材料的优化制备及性能表征

以低变质粉煤为原料,采用热解活化技术制备煤基多级孔炭纳米材料(CCNM),利用统计学预测分析软件(JMP)设计优化制备实验的正交阵列,主要因素包括煤直接液化残渣(DCLR)的添加量(A)、热解过程升温速率(B)、热解终温(C)和原料粒度(D),每个因素选取三个水平。采用响应面分析法对CCNM的碘吸附值和抗压强度进行评估,确定最佳优化条件为A1B3C1D2,影响因素按显著性由大到小的顺序为CABD,碘吸附值的预测公式为m I=258.26-33.22 x 1-34.88x 2+28.12x 21+1.92x 1x 2+34.12x 22,预测碘吸附值最高为390.51 mg/g,三组平行验证实验测定的碘吸附值平均为394.69 mg/g,实验值与预测值吻合良好。对优化条件下制备的CCNM进行性能表征,材料呈多孔结构;通过图像处理,统计得到孔隙率在40%以上;碘吸附值为398.22 mg/g,抗压强度为4.12 MPa,比表面积为146.181 m 2/g,总孔容为0.0534 cm 3/g,中孔率为71.10%,孔径主要分布在1.5 nm^100 nm,平均孔径为5.254 nm,表明CCNM是一种包含微孔、中孔和大孔的多级孔炭纳米材料。

Optimal Preparation and Performance Characterization of Coal-based Nanomaterials with Multi-stage Pore Structure

A pyrolysis activation technology of low-rank pulverized coal was adopted to prepare high strength coal-based carbon nanomaterials with multi-stage pore structure(CCNM).Statistical predictive analysis software(JMP)was used to give in orthogonal array of L 10(34)in experimental design.The parameters were the addition of coal direct liquefaction residue(DCLR)(A),heating rate in pyrolysis process(B),final temperature(C)and particle size of raw materials(D),each having three levels.According to the response surface analysis method,optimum condition for the iodine number and compressive strength is found to be A1B3C1D2,while the parameters in order of significance are CABD,and prediction formula for iodine number is also obtained as m I=258.26-33.22 x 1-34.88x 2+28.12x 21+1.92x 1x 2+34.12x 22,the highest predicted iodine adsorption value is 390.51 mg/g,the average value of iodine number determined by three parallel verification experiments is in good agreement with the predicted value of 394.69 mg/g.The performance of the CCNM prepared under optimized conditions was characterized.It shows multi-size pore structure in the surface morphology by the scanning electron microscope(SEM)test,and the porosity is more than 40%using image processing statistics.The iodine number is 398.22 mg/g,the compressive strength can reach 4.12 MPa,the specific surface area is 146.181 m 2/g,total pore volume is 0.0534 cm 3/g,the mesoporosity ratio is 71.10%,the pore size distribution is concentrated between 1.5 nm and 100 nm and the average pore diameter is 5.254 nm.These indicate that CCNM is a kind of carbon nanomaterials filled with microporous structure,mesoporous structure and macroporous structure.