(南京工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，南京 210009)
摘 要: 采用機(jī)械球磨法在LiAlH4+MgH2體系中添加不同種類催化劑，以提高復(fù)合體系的放氫性能。運(yùn)用XRD、SEM、EDS、XPS以及Sieverts法研究復(fù)合體系的結(jié)構(gòu)以及放氫性能，并探討TiF3 的催化機(jī)理。結(jié)果表明：TiF3催化劑的添加顯著降低了復(fù)合體系的起始放氫溫度，提高了放氫動(dòng)力學(xué)性能，該體系在84.1 ℃開(kāi)始脫氫，放氫量(質(zhì)量分?jǐn)?shù))達(dá)8.0%。熱脫附過(guò)程中TiF3參與了反應(yīng)，并生成含Tix+的未知化合物，有效地促進(jìn)了LiAlH4和MgH2之間的協(xié)同放氫。復(fù)合體系摻雜TiF3后，其熱脫附反應(yīng)的活化能Ea為79.1 kJ/mol，與未添加TiF3的復(fù)合體系的活化能(91.3 kJ/mol)相比，TiF3的添加極大地降低了放氫反應(yīng)動(dòng)力學(xué)勢(shì)壘。
關(guān)鍵字: LiAlH4；MgH2；TiF3；催化機(jī)理
（College of Materials Science and Engineering, Nanjing University of Technology, Nanjing 210009, China）
Abstract:The LiAlH4+MgH2 composites doped with different catalysts were prepared by mechanical milling to improve the hydrogen desorption properties. Structural and dehydrogenation properties of the composites were investigated by XRD, SEM, EDS, XPS and Sieverts method. The catalytic mechanism of TiF3 was also discussed. The results show that doping with TiF3 decreases effectively the onset hydrogen desorption temperature, and increases the dehydrogenation kinetics of the composite. The TiF3-doped system exhibits the onset hydrogen desorption temperature of 84.1 ℃ and hydrogen desorption capacity (mass fraction) of 8.0%. The unknown Tix+-containing compound forms during thermal desorption of the composite, which promotes effectively the synergetic dehydrogenation of LiAlH4 and MgH2. In addition, the dehydrogenation activation energy Ea of the composite doped with TiF3 is calculated by JMA equation to be 79.1 kJ/mol, which is much lower than that of the composite without TiF3 addition (91.3 kJ/mol), indicating that TiF3 addition decreases greatly the kinetic barrier for dehydrogenation.
Key words: LiAlH4; MgH2; TiF3; catalytic mechanism
