Dehydrogenation of Ammonia Borane Confined by Low-Density Porous Aromatic Framework

详细信息    查看全文

• 作者：Ye Peng ; Teng Ben ; Yi Jia ; Dongjiang Yang ; Huijun Zhao ; Shilun Qiu ; Xiangdong Yao
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：December 13, 2012
• 年：2012
• 卷：116
• 期：49
• 页码：25694-25700
• 全文大小：422K
• 年卷期：v.116,no.49(December 13, 2012)
• ISSN：1932-7455

文摘

Ammonia borane (AB) has been considered as an outstanding candidate material for on-board hydrogen storage due to its high stoichiometric hydrogen content (19.6 wt %) and moderate dehydrogenation temperature. However, slow dehydrogenation kinetics below 100 掳C and release of volatile byproducts (ammonia, borazine, and diborane) limited its practical applications. In this work, low-density and highly porous aromatic framework (PAF-1; BET, 4657 cm² g^鈥?; pore volume, 2.55 cm³ g^鈥?) was utilized as a template for the first time to nanoconfine AB molecules. The dehydrogenation behavior of the confined AB was studied by temperature-programmed desorption mass spectrometry (TPD-MS) and pressure鈥揷omposition鈥搕emperature (PCT) analyses. It was found that the AB molecules can be fully confined within the nanopores when the weight ratio of AB/PAF-1 is around 1:1. More importantly, AB started to dehydrogenate at very low temperature (around 50 掳C) with the peak of 77 掳C in the absence of any volatile byproducts such as ammonia, borazine, or diborane. Furthermore, about 4 wt % of hydrogen was evolved in the first 25 min at 75 掳C which is 27 times higher than the pristine AB, displaying higher kinetics at low temperatures. Compared with other porous supports such as MOFs, the PAF-1 has a very low framework density because it is built up only by light C and H elements. This could significantly improve the hydrogen systemic gravimetric capacity of the AB-confined system and thus increase feasibility in practical applications.