Carbon capture and storage (CCS) is broadly recognised as having the potential to play a key role in meeting climate change targets, delivering low carbon heat and power, decarbonising industry and, more recently, its ability to facilitate the net removal of CO2 from the atmosphere. However, despite this broad consensus and its technical maturity, CCS has not yet been deployed on a scale commensurate with the ambitions articulated a decade ago. Thus, in this paper we review the current state-of-the-art of CO2 capture, transport, utilisation and storage from a multi-scale perspective, moving from the global to molecular scales. In light of the COP21 commitments to limit warming to less than 2 °C, we extend the remit of this study to include the key negative emissions technologies (NETs) of bioenergy with CCS (BECCS), and direct air capture (DAC). Cognisant of the non-technical barriers to deploying CCS, we reflect on recent experience from the UK's CCS commercialisation programme and consider the commercial and political barriers to the large-scale deployment of CCS. In all areas, we focus on identifying and clearly articulating the key research challenges that could usefully be addressed in the coming decade.

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Carbon capture and storage (CCS): the way forward

: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Development of novel technologies for the efficient and reversible capture of CO2 is highly desired. In the last decade, CO2 capture using ionic liquids has attracted intensive attention from both academia and industry, and has been recognized as a very promising technology. Recently, a new approach has been developed for highly efficient capture of CO2 by site-containing ionic liquids through chemical interaction. This perspective review focuses on the recent advances in the chemical absorption of CO2 using site-containing ionic liquids, such as amino-based ionic liquids, azolate ionic liquids, phenolate ionic liquids, dual-functionalized ionic liquids, pyridine-containing ionic liquids and so on. Other site-containing liquid absorbents such as amine-based solutions, switchable solvents, and functionalized ionic liquid–amine blends are also investigated. Strategies have been discussed for how to activate the existent reactive sites and develop novel reactive sites by physical and chemical methods to enhance CO2 absorption capacity and reduce absorption enthalpy. The carbon capture mechanisms of these site-containing liquid absorbents are also presented. Particular attention has been paid to the latest progress in CO2 capture in multiple-site interactions by amino-free anion-functionalized ionic liquids. In the last section, future directions and prospects for carbon capture by site-containing ionic liquids are outlined.

Active chemisorption sites in functionalized ionic liquids for carbon capture

High cost and high energy penalty for CO2 uptake from flue gases are important obstacles in large-scale industrial applications, and developing efficient technology for CO2 capture from technical a ...

Carbon Dioxide Capture with Ionic Liquids and Deep Eutectic Solvents: A New Generation of Sorbents

The efficient capture of SO2 is of great significance in gas-purification processes including flue-gas desulfurization and natural-gas purification, but the design of porous materials with high adsorption capacity and selectivity of SO2 remains very challenging. Herein, the selective recognition and dense packing of SO2 clusters through multiple synergistic host-guest and guest-guest interactions by controlling the pore chemistry and size in inorganic anion (SiF62- , SIFSIX) pillared metal-organic frameworks is reported. The binding sites of anions and aromatic rings in SIFSIX materials grasp every atom of SO2 firmly via Sδ+ ···Fδ- electrostatic interactions and Oδ- ···Hδ+ dipole-dipole interactions, while the guest-guest interactions between SO2 molecules further promote gas trapping within the pore space, which is elucidated by first-principles density functional theory calculations and powder X-ray diffraction experiments. These interactions afford new benchmarks for the highly efficient removal of SO2 from other gases, even if at a very low SO2 concentration. Exceptionally high SO2 capacity of 11.01 mmol g-1 is achieved at atmosphere pressure by SIFSIX-1-Cu, and unprecedented low-pressure SO2 capacity is obtained in SIFSIX-2-Cu-i (4.16 mmol g-1 SO2 at 0.01 bar and 2.31 mmol g-1 at 0.002 bar). More importantly, record SO2 /CO2 selectivity (86-89) and excellent SO2 /N2 selectivity (1285-3145) are also achieved. Experimental breakthrough curves further demonstrate the excellent performance of these hybrid porous materials in removing low-concentration SO2 .

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Ultrahigh and Selective SO2 Uptake in Inorganic Anion-Pillared Hybrid Porous Materials.

Five kinds of anion-functionalized ionic liquids (ILs) with different basicity and substituent were selected, prepared and applied in the capture of SO2 from flue gas, where the concentration of SO2 is only 2000 ppm. The effect of the anion on SO2 absorption capacity, desorption residue, and available absorption capacity under 2000 ppm was investigated. The relationship between available absorption capacity and absorption enthalpy was also studied. Through a combination of thermodynamic analysis and quantum calculation, the results indicated that the effect of the cation in the IL on absorption enthalpy was significant. However, the effect of chain length in the cation was weak. Hence, a new IL with low molecular weight, [P4442][Tetz], was further designed and applied for the capture of SO2, which shows the high absorption capacity of 0.18 g SO2 per g IL and excellent reversibility for 2000 ppm SO2. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2028–2034, 2015

Designing of anion-functionalized ionic liquids for efficient capture of SO2 from flue gas

Highly efficient SO2 capture by phenyl-containing azole-based ionic liquids through multiple-site interactions

Highly efficient CO2 capture by carbonyl-containing ionic liquids through Lewis acid–base and cooperative C–H⋯O hydrogen bonding interaction strengthened by the anion

Global context information is essential for the semantic segmentation of remote sensing (RS) images. However, most existing methods rely on a convolutional neural network (CNN), which is challenging to directly obtain the global context due to the locality of the convolution operation. Inspired by the Swin transformer with powerful global modeling capabilities, we propose a novel semantic segmentation framework for RS images called ST-U-shaped network (UNet), which embeds the Swin transformer into the classical CNN-based UNet. ST-UNet constitutes a novel dual encoder structure of the Swin transformer and CNN in parallel. First, we propose a spatial interaction module (SIM), which encodes spatial information in the Swin transformer block by establishing pixel-level correlation to enhance the feature representation ability of occluded objects. Second, we construct a feature compression module (FCM) to reduce the loss of detailed information and condense more small-scale features in patch token downsampling of the Swin transformer, which improves the segmentation accuracy of small-scale ground objects. Finally, as a bridge between dual encoders, a relational aggregation module (RAM) is designed to integrate global dependencies from the Swin transformer into the features from CNN hierarchically. Our ST-UNet brings significant improvement on the ISPRS-Vaihingen and Potsdam datasets, respectively. The code will be available at https://github.com/XinnHe/ST-UNet.

Swin Transformer Embedding UNet for Remote Sensing Image Semantic Segmentation

A strategy for improving CO2 capture by imidazolium ionic liquids (ILs) through a reduction in the formation of carbene–CO2 complex was reported. The carbene–CO2 complex content in CO2 capture by imidazolium ILs was determined by a quantitative NMR method, and the carbene–CO2 complex formation was decreased through a reduction in the basicity of the anion and an enlargement in the steric hindrance of the cation. Thus, both enhanced absorption capacity and improved desorption were achieved, where an ideal IL, [Ipmim][Triz], exhibited a very high capacity of 0.21 g of CO2/g of IL and excellent reversibility.

Xi He

Papers

Designing of anion-functionalized ionic liquids for efficient capture of SO2 from flue gas

Highly efficient SO2 capture by phenyl-containing azole-based ionic liquids through multiple-site interactions

Highly efficient CO2 capture by carbonyl-containing ionic liquids through Lewis acid–base and cooperative C–H⋯O hydrogen bonding interaction strengthened by the anion

Swin Transformer Embedding UNet for Remote Sensing Image Semantic Segmentation

Highly Efficient CO2 Capture by Imidazolium Ionic Liquids through a Reduction in the Formation of the Carbene–CO2 Complex