Journal Article

Cooperative insertion of CO2 in diamine-appended metal-organic frameworks

Kortright, Jeffrey B., Odoh, Samuel O., Pascal, Tod, Planas, Nora, Bordiga, Silvia, Gygi, David, Schnell, Sondre K., Reimer, Jeffrey A., Long, Jeffrey R., Bloch, Eric D., Giordanino, Filippo, Mason, Jarad A., Dani, Alessandro, Poloni, Roberta, Wan, Liwen F., Dzubak, Allison L., Smit, Berend, Crocellà, Valentina, Lee, Kyuho, Neaton, Jeffrey B., Prendergast, David, Vlaisavljevich, Bess, Drisdell, Walter S., Kong, Xueqian, Gagliardi, Laura, McDonald, Thomas M.

2015

Overview

The process of carbon capture and sequestration has been proposed as a method of mitigating the build-up of greenhouse gases in the atmosphere. If implemented, the cost of electricity generated by a fossil fuel-burning power plant would rise substantially, owing to the expense of removing CO 2 from the effluent stream. There is therefore an urgent need for more efficient gas separation technologies, such as those potentially offered by advanced solid adsorbents. Here we show that diamine-appended metal-organic frameworks can behave as ‘phase-change’ adsorbents, with unusual step-shaped CO 2 adsorption isotherms that shift markedly with temperature. Results from spectroscopic, diffraction and computational studies show that the origin of the sharp adsorption step is an unprecedented cooperative process in which, above a metal-dependent threshold pressure, CO 2 molecules insert into metal-amine bonds, inducing a reorganization of the amines into well-ordered chains of ammonium carbamate. As a consequence, large CO 2 separation capacities can be achieved with small temperature swings, and regeneration energies appreciably lower than achievable with state-of-the-art aqueous amine solutions become feasible. The results provide a mechanistic framework for designing highly efficient adsorbents for removing CO 2 from various gas mixtures, and yield insights into the conservation of Mg 2+ within the ribulose-1,5-bisphosphate carboxylase/oxygenase family of enzymes. A cooperative insertion mechanism for CO 2 adsorption is shown to generate highly efficient adsorbents for carbon capture applications. Efficient CO 2 absorption in a metal-organic framework Advanced solid adsorbents are being investigated as potential agents for efficient gas separation technologies that could help make carbon capture technologies more economical. This paper probes the mechanism of carbon dioxide adsorption of a previously reported diamine-appended metal-organic framework. This material demonstrates unusual and potentially practically useful adsorption properties. The authors find that CO 2 adsorbs through insertion into the highly stable metal-amine bonds of the metal-organic framework. As a consequence of the homogenous and perfect spacing of amines, as dictated by the framework's topology, the insertion of a single CO 2 molecule induces neighbouring sites to also adsorb CO 2 in an unprecedented chain reaction process.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 119/118 / 140/131 / 639/638/298/921 / Adsorbents / Adsorption / Amines / Amines - chemistry / Ammonium / Bond strength / Carbon dioxide / Carbon Dioxide - chemistry / Carbon Dioxide - isolation & purification / Carbon Sequestration / Chemical Sciences / Cost control / Effluent streams / Electric power generation / Flue gas / Fossil fuels / Greenhouse Effect - prevention & control / Greenhouse gases / Heat transfer / Humanities and Social Sciences / Ligands / Magnesium - metabolism / Material chemistry / membrane, carbon capture, materials and chemistry by design, synthesis (novel materials), synthesis (self-assembly), synthesis (scalable processing) / Metals / multidisciplinary / Ribulose-Bisphosphate Carboxylase - chemistry / Ribulose-Bisphosphate Carboxylase - metabolism / Science / Temperature / X-Ray Diffraction