Densification-Induced Structure Changes in Basolite MOFs: Effect on Low-Pressure CH4 Adsorption.

David Ursueguía,Eva Díaz,Salvador Ordóñez

doi:10.3390/nano10061089

Abstract

Metal-organic frameworks’ (MOFs) adsorption potential is significantly reduced by turning the original powder into pellets or granules, a mandatory step for their use at industrial scale. Pelletization is commonly performed by mechanical compression, which often induces the amorphization or pressure-induced phase transformations. The objective of this work is the rigorous study of the impact of mechanical pressure (55.9, 111.8 and 186.3 MPa) onto three commercial materials (Basolite C300, F300 and A100). Phase transformations were determined by powder X-ray diffraction analysis, whereas morphological changes were followed by nitrogen physisorption. Methane adsorption was studied in an atmospheric fixed bed. Significant crystallinity losses were observed, even at low applied pressures (up to 69.9% for Basolite C300), whereas a structural change occurred to Basolite A100 from orthorhombic to monoclinic phases, with a high cell volume reduction (13.7%). Consequently, adsorption capacities for both methane and nitrogen were largely reduced (up to 53.6% for Basolite C300), being related to morphological changes (surface area losses). Likewise, the high concentration of metallic active centers (Basolite C300), the structural breathing (Basolite A100) and the mesopore-induced formation (Basolite F300) smooth the dramatic loss of capacity of these materials.

Highlights

Energy demand estimations for the decades, mainly due to the global population and industrialization process increments, boost the development of techniques and processes able to make the most of available resources [1]
Particles were used in powder form, being the commercial size: Basolite C300 (16 μm, D50), Basolite F300 (5 μm) and Basolite A100 (32 μm, D50)
For Basolite A100, a flexible crystalline Metal-organic frameworks’ (MOFs), a transformation is observed from orthorhombic disposition to monoclinic structure from 55.9 MPa onwards, in addition to high permanent losses of microporosity due to agglomeration

Summary

Introduction

Energy demand estimations for the decades, mainly due to the global population and industrialization process increments, boost the development of techniques and processes able to make the most of available resources [1]. Even when electricity from wind and solar would satisfy the majority of demand, systems need to maintain flexibility in order to be able to ramp up other sources of generation quickly when the pattern of supply shifts, such as when the sun sets. Electricity system operators have to constantly balance demand and supply in real time to prevent blackouts, which in recent times occurred mainly during periods of low demand [2]. In this context, natural gas power plants can quickly ramp generation up or down at short notice, providing in this way flexibility, underlining the critical role of gas in the longed-for clean energy transition

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