响应面优化设计棕榈壳活性炭的制备及储氢性能研究

Preparation of Activated Carbons from Palm Shell by Response Surface Optimization Design and Its Hydrogen Storage Performance

以生物质材料棕榈壳作原料,采用KOH活化方法制备高比面积活性炭,以比表面积和微孔孔容作为考察目标,分别通过单因素试验和响应面法探究不同的制备工艺条件的影响及其最优工艺参数,并考察了最佳工艺条件下制备的活性炭的储氢性能。研究结果表明:活化温度和浸渍比值对比表面积和微孔孔容均具有显著影响,以微孔孔容模型进行预测优化得到的最优工艺参数为活化温度795℃,浸渍比值3.64,制备得到的棕榈壳活性炭的平均比表面积和微孔孔容分别为3491 m^(2)/g和1.08 cm^(3)/g。孔结构分析结果表明:棕榈壳活性炭主要以微孔为主,微孔率最高可到89%,也有中孔并存。从扫描电镜和透射电镜图也可以看出活性炭存在大量微孔和中孔,两者结果一致。同时棕榈壳活性炭的储氢性能优异,在-196℃和4 MPa条件下,其过量储氢量和绝对质量储氢量可分别高达6.4%和6.8%。

The palm shell was used as precursor to prepare activated carbons with high specific surface area by KOH activation method.The specific surface area and micropore pore volume were taken as the inspection targets,the influence of different preparation process conditions was explored through single factor experiments and central composite design methods.The hydrogen storage performance of activated carbons prepared under the optimal conditions was studied.The results showed that the activation temperature and the weight ratio of KOH/palm shell char had significant effects on the surface area and micropore volume.The preparation parameters obtained after optimization were 795℃for activation temperature and 3.64 for impregnation ratio.The average specific surface area and micropore volume of activated carbon prepared under these conditions were 3491 m^(2)/g and 1.08 cm^(3)/g,respectively.The pore structure analysis results showed that palm shell-based activated carbon was mainly composed of micropores and mesopores,with the maximum microporosity of 89%.Furthermore,it could be seen from the SEM and TEM images that there were a large number of micropores and mesopores distributed in activated carbon.Meanwhile,palm shell activated carbon had excellent hydrogen storage performance.The excess and absolute hydrogen storage capacities were as high as 6.4%and 6.8%under the conditions of-196℃and 4 MPa,respectively.