烟煤粘结纳米镁基储氢材料的制备及吸放氢性能

摘要

Nanostructured Mg-based hydrogen storage material with bituminous coal as binder and carbonized anthracite coal as milling aid was prepared by hydrogen reaction ball milling and heat treatment.The structure and hydrogen storage properties of the material were investigated,and the hydrogen absorption kinetics param-eter was calculated.Results show that the carbon in the material can react with Mg,and Mg2 C3 was generated when the material gets heat treated at 600℃,while at 500℃ the nano-structured Mg particles are well binded with 15wt% of bituminous coal without the generation of Mg2C3.The hydrogen absorbing rate was enhanced with the increase of temperature,and the hydrogen uptake reached to 3.77wt% at 350℃,2 MPa H2 and a little reduction at 400℃.According to Arrhenius equation,the apparent activation energy for the first order reaction of hydrogen absorbing within 300-350℃ was 56.6kJ/mol H2 .The initial and peak hydrogen desorption temper-atures are 250 and 388℃,respectively.In the hydriding process,the carbon in the material can combine a small amount of hydrogen which can be released in the form of alkane like methane and ethane.%以Mg、烟煤和碳化无烟煤为原料,经 H 2反应球磨、热处理制备了烟煤粘结的纳米镁基储氢材料,研究了储氢材料结构及吸放氢性能,并计算了材料的吸氢动力学参数。结果表明,在600℃热处理时材料中的Mg容易与煤中的 C 发生反应生成 Mg2 C3；添加15%(质量分数)烟煤,经500℃热处理能有效粘结纳米Mg颗粒,且未见Mg2 C3生成。储氢材料的吸氢速率随温度升高而增大,在2MPa H2下吸氢量在350℃达到最大值,约3.77%(质量分数),在400℃时吸氢量略有下降。根据 Arrhenius 公式得出储氢材料在300~350℃下吸氢的一级反应表观活化能为56.6kJ/mol H 2。用TPD测定了储氢材料的放氢温度,表明材料在250℃开始放氢,388℃时达到放氢高峰。储氢材料中的C 可结合少量 H,该类 H 在加热时会以 CH4等烃的形式释放出来。