Materials and Processes for Carbon Capture and Sequestration

The field of sustainability in chemistry is largely dedicated to development of energy and chemical sources that do not rely on fossil-based carbon. Renewable power efforts based on solar, wind, geothermal, tidal, and biomass-derived energy are all under rapid development. In parallel, renewable chemicals based on biomass feedstocks are being developed. Nonetheless, the world today is dominated by fossil power (coal, petroleum, gas) and most chemicals and materials that drive modern society are also derived from fossil resources. This profile is not expected to change rapidly, and given the effects of fossil-derived CO2 on the global climate, there is increased emphasis, today, on the development of technologies for the capture and sequestration of carbon dioxide. Carbon capture and sequestration (CCS) is a relatively new term that is usually applied to describe processes for capturing anthropogenic CO2 from large point sources, with the prototypical target being a large, coal-fired power plant. From this point source, materials and processes for capturing and concentrating CO2 are needed, followed by compression and pipelining, ultimately allowing for sequestration, for example, in underground geological formations. Of course, there are many possible iterations on this base strategy, including development of novel power plant designs that are more amenable to carbon capture [e.g., oxycombustion, integrated gasification combined cycle (IGCC) processes] and disposition of the CO2, to a small degree, in other ways, such as feedstocks for fuel (e.g., algae production), chemical, or material synthesis. A whole host of technical challenges must be overcome to make CCS practical and cost effective. These include the development of materials that enable the separation of CO2 from combustion gases to be carried out in an efficient manner, the design of CCS processes that can be integrated with existing power generation infrastructure, and safe and verifiable methods for sequestering CO2. All of these needs have mobilized the chemical science and engineering communities to both develop the basic science of carbon capture and sequestration, as well as provide novel, practical solutions to the grand challenge of global carbon management. In this special issue dedicated to CCS, we have collected an array of invited and contributed papers that address the challenges of CCS, with a strong emphasis on carbon capture. The issue includes 13 contributions, including 2 Minireviews, 1 Communication, and 10 Full Papers. The first contribution, by Sholl and co-workers, highlights the emerging field of metal–organic-framework (MOF) materials, and the roles they may play in carbon capture. In particular, the authors highlight key areas relevant to CCS where relatively important questions remain unanswered and key work remains to be done. The second Minireview, by Grande et al., assesses the potential of electric-swing adsorption processes for CCS. The Minireviews are followed by a Communication by Jones and co-workers that addresses the issue of sorbent regeneration and concentration of CO2 after capture by adsorption. This is followed by the first Full Paper, which is the only contribution in this issue that focuses exclusively on carbon sequestration. In this work, House and co-workers compare the mobility and footprint of CO2 in marine sediments and terrestrial reservoirs, considering the possibility of CO2 storage in such formations. The remaining articles focus on carbon capture, primarily by means of absorption in solvents or adsorption with solids. Rochelle and co-workers characterize the utility of aqueous ethylenediamine solutions, alternatives to benchmark monoethanolamine solvents, for CO2 capture. Perry et al. describe their work on aminosilicone mixtures as new solvents for CO2 absorption. Mindrup and Schneider use density functional theory (DFT) to characterize the interactions of CO2 with a variety of different amine structures. Of course, not all functional CO2 solvents are based on amines, and Nijmeijer and co-workers describe their work on use of amino acid salt solutions in gas–liquid membrane contactors for carbon capture, in the next contribution. Supported amines are useful solid materials for the adsorptive separation of CO2 from gas streams. Kitchin and co-workers describe their work on activated carbon supported amidines for CO2 adsorption, and present a thermodynamic analysis of the Gibbs energy of capture. Tanthana and Chuang investigate the role of polyethylene glycol (PEG) in stabilizing silica-supported tetraethylpentamine adsorbents via in situ FTIR spectroscopy. Luo et al. describe the use of metal-substituted layered double hydroxides for CO2 adsorption, demonstrating how the use of different metals in the layered structure requires different processing conditions to obtain sorbents with optimal adsorption capacities. A contribution on use of high surface area carbon molecular sieves for CO2 adsorption by Silvestre-Albero is the next article. The final article in the issue describes a molecular simulation study, by Chen and Jiang, of amine-containing MOFs for CO2 adsorption, thus ending the issue on the same class of materials described in the first contribution, metal–organic frameworks. On behalf of the ChemSusChem editorial team, we hope that you enjoy this issue, and that the future will see many exciting new contributions from chemical science aimed at solving the problems facing CCS.1 1 Atlanta, Georgia, USA and Notre Dame, Indiana, USA, September, 2010.