Abstract
Hydrogen has long been touted as a replacement energy vector for fossil fuels in transport applications, as it boasts a number of benefits: it is abundant; relatively easy to produce; has the highest gravimetric energy density of any known chemical fuel; and is a ‘zero carbon’ fuel as it only produces water upon full combustion. However, hydrogen is a very sparse gas under standard conditions, and as such has a very low volumetric energy density. Therefore, one of the great issues to overcome in creating a ‘hydrogen economy’ is how to store this elemental fuel. The current industrial standard is compress the gas to 70 MPa in type III or type IV carbon fibre composite tanks. However, this method requires high strength, low density materials to be suitable for safe automotive applications, which are expensive. One alternative method for densifying hydrogen is the use of physisorption, in which the gas molecules interact with the surfaces of high surface area materials, allowing similar density rises but at lower pressures.
This study is focussed on synthesising, characterising and modelling a novel adsorbent composite made from the polymer of intrinsic porosity PIM-1 and the metal organic framework MIL-101, around which a conceptual hydrogen tank will be designed. PIM-1 is a very interesting adsorbent as it is a fully soluble in polar aprotic solvents and can therefore be cast into films, without losing much of its porosity. This is due to its kinked and rigid molecular chains, which are incapable of relaxing fully and therefore maintain free volume within the material [1]. PIM-1 typically shows BET surface areas of ~ 800 m2 g-1, and a hydrogen uptake of 1.45 wt% at 77 K and 10 bar [2], which are low values and require improvement for use in an effective storage system. This study looks to perform this by embedding MIL-101 in a mixed matrix membrane-style film. MIL-101 is a popular and well-studied MOF, offering surface areas in excess of 3000 m2 g-1 and hydrogen uptakes as high as 6 wt% at 77 K and 8 MPa [3]. It is also thermally and hydrolytically stable.
This study presents the synthesis of both materials and a number of composites of the two in varying quantities. These materials are then characterised for their adsorptive (N2, CO2, H2 isotherms) and thermal (TG-MS, DSC) properties, and the hydrogen adsorption behaviour modelled in preparation for a conceptual design. The relationship between composite composition and these properties will also be presented in a rule-of-mixtures style analysis.
References:
[1] Budd PM, Elabas ES, Ghanem BS, et al. Solution-Processed, Organophilic Membrane Derived from a Polymer of Intrinsic Microporosity. Adv Mater., 2004, 16, 456–459.
[2] McKeown NB, Budd PM & Book D. Microporous Polymers as Potential Hydrogen Storage Materials, Macromol. Rapid Commun. 2007, 28, 995–1002
[3] Latroche M, Surblé S, Serre C et al. Hydrogen Storage in the Giant-Pore Metal-Organic Frameworks MIL-100 and MIL-101, Angew. Chem. Int. Ed. 2006, 45, 8227–8231
Original language | English |
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Publication status | Unpublished - 13 Dec 2016 |
Event | H2FC: Hydrogen & Fuel Cell SUPERGEN Researcher Conference - University of Ulster, Jordanstown Campus, Belfast, UK United Kingdom Duration: 12 Dec 2016 → 14 Dec 2016 http://www.h2fcsupergen.com/conference/ |
Conference
Conference | H2FC: Hydrogen & Fuel Cell SUPERGEN Researcher Conference |
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Abbreviated title | H2FC SUPERGEN Conference |
Country/Territory | UK United Kingdom |
City | Belfast |
Period | 12/12/16 → 14/12/16 |
Internet address |
Keywords
- hydrogen
- storage
- adsorption
- PIM
- MOF
- composite