During the MAVO project functionalized MOF materials will be developed and produced and their application as storage materials for reactive gases will be demonstrated.
Furthermore, innovative composite material products will be developed, which have a high thermal conductivity, good mass transport properties of sponge-like structures in combination with a high adsorption capacity of the adsorbents. Following the established techniques for the production of metal foams, a more open sponge-like structure made from an adsorbent and heat conducting components, will be generated.
Metal-Organic frameworks have shown through their large specific pore volume and their large internal surface, a very good characteristic for gas adsorption, which, in turn can be used for example as a gas storage. This can in principle be any gas. The storage of reactive gases in particular offers a delightful application perspective. Utilising this technique the logistical, safety and economic costs in the safe storage and handling of reactive gases during the operations in chemical process can be significantly reduced.
The field of reactive gas storage was put into effect at the Fraunhofer ICT using special measuring equipment for the qualitative and quantitative characterization of MOF substances in the presence of reactive gases. MOF substances can thus be characterized in detail in reactive gas impingement in terms of their chemical compatibility and stability, and to their sorption behaviour.
For selected reactive gases, such as sulphur dioxide SO2, promising MOF substances have been identified which allow a quantitative loading. In addition, works for post synthetic modification of MOF substances are currently carried out, with the aim to achieve a stronger chemical inerting and an increase of storage capacity for the selected reactive gases.
The subproject “Storage of Fuels” focusses on the development of a MOF-based composite for methane storage applications with optimized heat transmitting properties.
MOFs are being considered as excellent candidates for storing gaseous fuels like methane or hydrogen. However, the practical implementation of MOFs is still limited since they feature only poor heat conducting characteristics which are attended by emerging thermal effects at charging/discharging processes. Therefore, MOF-based materials with enhanced thermal conductivity are needed, especially with regard to automotive applications.
Within the scope of the subproject “Storage of Fuels” Fraunhofer Institute UMSICHT succeeded to develop a MOF-composite material combining both high adsorption capacities and good heat conducting properties.
For fabrication of this composite a common MOF with high methane storage capacity is used. A highly heat conductive material as well as a binding agent are added to the MOF before this mixture is transferred into a porous shaped body by molding.
Analysis of the composite shows, that the effective thermal conductivity is enhanced significantly by the additive. Furthermore, as adsorption measurements confirm, neither pore structure nor pore-accessibility of the processed MOF are influenced negatively by molding. Thus, methane adsorption capacity of the MOF remains constantly high.
Moreover, macro-pores respectively inter-particle spaces in the composite are likewise of high importance, since they affect the gas flow through the material and are therefore crucial for an optimal and fast mass transport. First analytic results show here, too, that the characteristics of the composite are beneficial on this aspect as well.
The objective of further investigations is to analyze the developed composite regarding its mechanical stability as well as the long-term adsorption characteristics.