Sunday, September 14, 2008

A High-Capacity CO2 Trap

A porous material created by a team led by Gérard Férey at Institut Lavoisier in Versailles1 has an unparalleled ability to capture carbon dioxide, a major challenge in the ongoing fight against global warming.

This recent study2 co-authored by several laboratories associated with CNRS3 has shown that MIL101, a mesoporous4 Metal-Organic Framework (MOF), could store close to 400 m3 of CO2 at 25°C per m3 of solid, almost double the capacity of the best materials commercially available today.

Yet when Férey initially set out to create porous frameworks, he had no specific application in mind. His goal was to move beyond trial and error and devise a logical approach to create tailored porous solids. Using a personal computer simulation program, he found extraordinary virtual results. They eventually led to the creation of MIL101, the largest crystalline porous solid to date, with pores of 3.4 nm and a huge cubic cell volume.

The next issue was to figure out what to trap in such large cages and, given the increased focus on the reduction of greenhouse gas emissions, CO2 was a prime candidate. Férey also gives credit to his colleagues who demonstrated MIL101’s record CO2 adsorption properties. “We now know why and where the CO2 molecules attach,” he points out. “This is essential information if we want to find even better products.”

The study also shows that the method chosen to activate MIL101 is crucial in optimizing its CO2 adsorption capability, the most effective method being a combination of hot ethanol and ammonium fluoride treatments. CO2 storage is only one of many potential applications for a large-pore MOF and the possibilities are practically endless. “You can fill it with pretty much anything,” concludes Férey, “hydrogen, drugs, or even use the cages as a nanoreactor to produce materials directly inside them.”

Fabien Buliard

Notes :
1. CNRS / Université de Versailles.2. P. L. Llewellyn et al., “High Uptakes of CO2 and CH4 in Mesoporous Metal-Organic Frameworks MIL-100 and MIL-101,” Langmuir, 2008. DOI 10.1021/1a800227x.3. Institut Lavoisier (CNRS / Université de Versailles), Institut Charles Gerhardt (CNRS / Université de Montpellier-II / ENSCM), Laboratoire chimie Provence (CNRS / Universités Aix-Marseille-I, II and III), Laboratoire catalyse et spectrochimie (CNRS / Ensi Caen / Université de Caen).4. A material with pore diameters of 2 to 50 nm in size.

Contacts : Gérard Férey, Institut Lavoisier,

Courtesy: Dr S Vasudevan

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