271665 Active Role of Carbon Dioxide in the Dehydrogenation of B-N-H Compounds

Tuesday, October 30, 2012: 2:10 PM
305 (Convention Center )
Ran Xiong1, Junshe Zhang2,3 and Jae W. Lee2, (1)Chemical Engineering, CCNY, New York, NY, (2)Department of Chemical Engineering, The City College of New York, New York, NY, (3)Chemical and Biomolecular, KAIST, Daejeon, South Korea

B-N-H compounds including ammonia borane (AB, NH3BH3) and polymeric aminoborane (PAB, (H2BNH2) n) are promising on-board hydrogen storage materials. To satisfy the DOE 2017 target (5.5 wt% H2 based on the total system), about 11 wt% H2 should be usable from a storage material. Thus, the research challenge is to propose a facile and economical method to extract 11 wt% H2 from the starting material of AB at the working temperature of fuel cell (80 – 90 oC). The present study has found that gaseous CO2 environments can enhance the dehydrogenation of AB and PAB. After AB is pre-treated at 70 oC and with 1.38 MPa of carbon dioxide (CO2) for 38 min, the rapid hydrogen release of 1.5 moles H2 per mol of AB was achieved within 1 hour at 85oC. Furthermore, when PAB, the spent fuel of AB with 0.91 equivalent hydrogen release, was exposed to 2.07Mpa of CO2 at 85oC, the rapid hydrogen desorption of 0.84 mol H2 per mol of AB was observed. The total hydrogen release starting from AB is 11.4 wt% based on an initial mass of AB. For both cases, the degree of dehydrogenation is confirmed by ATR-FTIR spectroscopic and elemental analyses of the thermolytic solid products. Based on the IR, Raman, and elemental analyses of the solid products, we will address a possible mechanism for the enhanced dehydrogenation of AB and PAB in CO2 environments.

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