In recent years, Carbon Capture and Storage (Sequestration) (CCS) has been proposed as a potential method to allow the continued use of fossil-fuelled power stations whilst preventing emissions of CO2 from reaching the atmosphere. Gas, coal (and biomass)-fired power stations can respond to changes in demand more readily than many other sources of electricity production, hence the importance of retaining them as an option in the energy mix. Here, we review the leading CO2 capture technologies, available in the short and long term, and their technological maturity, before discussing CO2 transport and storage. Current pilot plants and demonstrations are highlighted, as is the importance of optimising the CCS system as a whole. Other topics briefly discussed include the viability of both the capture of CO2 from the air and CO2 reutilisation as climate change mitigation strategies. Finally, we discuss the economic and legal aspects of CCS.

Carbon capture and storage update

Carbon dioxide (CO2) capture using solid sorbents has been recognized as a very promising technology that has attracted intense attention from both academic and industrial fields in the last decade. It is astonishing that around 2000 papers have been published from 2011 to 2014 alone, which is less than three years after our first review paper in this journal on solid CO2 sorbents was published. In this short period, much progress has been made and the major research focus has more or less changed. Therefore, we feel that it is necessary to give a timely update on solid CO2 capture materials, although we still have to keep some important literature results published in the past years so as to keep the good continuity. We believe this work will benefit researchers working in both academic and industrial areas. In this paper, we still organize the CO2 sorbents according to their working temperatures by classifying them as such: (1) low-temperature ( 400 °C). Since the sorption capacity, kinetics, recycling stability and cost are important parameters when evaluating a sorbent, these features will be carefully considered and discussed. In addition, due to the huge amounts of cost-effective CO2 sorbents demanded and the importance of waste resources, solid CO2 sorbents prepared from waste resources and their performance are reviewed. Finally, the techno-economic assessments of various CO2 sorbents and technologies in real applications are briefly discussed.

Recent advances in solid sorbents for CO2 capture and new development trends

It is generally accepted by the scientific community that anthropogenic CO2 emissions are leading to global climate change, notably an increase in global temperatures commonly referred to as global warming. The primary source of anthropogenic CO2 emissions is the combustion of fossil fuels for energy. As society’s demand for energy increases and more CO2 is produced, it becomes imperative to decrease the amount emitted to the atmosphere. One promising approach to do this is to capture CO2 at the effluent of the combustion site, namely, power plants, in a process called postcombustion CO2 capture. Technologies to achieve this are heavily researched due in large part to the intuitive nature of removing CO2 from the stack gas and the ease in retrofitting existing CO2 sources with these technologies. As such, several reviews have been written on postcombustion CO2 capture. However, it is a fast-developing field, and the most recent review papers already do not include the state-of-the-art research. Notable am...

Amine-Based CO2 Capture Technology Development from the Beginning of 2013—A Review

Dramatically increased CO2 concentration from several point sources is perceived to cause severe greenhouse effect towards the serious ongoing global warming with associated climate destabilization, inducing undesirable natural calamities, melting of glaciers, and extreme weather patterns. CO2 capture and utilization (CCU) has received tremendous attention due to its significant role in intensifying global warming. Considering the lack of a timely review on the state-of-the-art progress of promising CCU techniques, developing an appropriate and prompt summary of such advanced techniques with a comprehensive understanding is necessary. Thus, it is imperative to provide a timely review, given the fast growth of sophisticated CO2 capture and utilization materials and their implementation. In this work, we critically summarized and comprehensively reviewed the characteristics and performance of both liquid and solid CO2 adsorbents with possible schemes for the improvement of their CO2 capture ability and advances in CO2 utilization. Their industrial applications in pre- and post-combustion CO2 capture as well as utilization were systematically discussed and compared. With our great effort, this review would be of significant importance for academic researchers for obtaining an overall understanding of the current developments and future trends of CCU. This work is bound to benefit researchers in fields relating to CCU and facilitate the progress of significant breakthroughs in both fundamental research and commercial applications to deliver perspective views for future scientific and industrial advances in CCU.

Industrial carbon dioxide capture and utilization: state of the art and future challenges

Chemical looping combustion of solid fuels

Zn-based Al2O3-suported materials have been proposed as inexpensive and environmentally friendly catalysts for the direct dehydrogenation of propane (PDH), however, our understanding of these catalysts’ structure and deactivation routes is still limited. Here, we correlate the catalytic activity for PDH of a series of Zn-based Al2O3 catalysts with their structure and structural evolution. To this end, three model catalysts are investigated. (i) ZnO/Al2O3 prepared by atomic layer deposition (ALD) of ZnO onto γ-Al2O3 followed by calcination at 700 °C, which yields a core-shell spinel zinc aluminate/γ-Al2O3 structure. (ii) Zinc aluminate spinel nanoparticles (ZnxAlyO4 NPs) prepared via a hydrothermal method. (iii) A reference core-shell ZnO/SiO2 catalyst prepared by ALD of ZnO on SiO2. The catalysts are characterized in detail by synchrotron X-ray powder diffraction (XRD), Zn K-edge X-ray absorption spectroscopy (XAS), and 27Al solid state nuclear magnetic resonance (ssNMR). These experiments allowed us to identify tetrahedral Zn sites in close proximity to Al sites of a zinc aluminate spinel phase (ZnIV–O–AlIV/VI linkages) as notably more active and selective in PDH relative to the supported ZnO wurtzite phase (ZnIV–O– ZnIV linkages) in ZnO/SiO2. The best performing catalyst, 50ZnO/Al2O3 gives 77% selectivity to propene (gaseous products based) at 9 mmol C3H6 gcat−1 h−1 space time yield (STY) after 3 min of reaction at 600 °C. On the other hand, the core-shell ZnO/Al2O3 catalyst shows an irreversible loss of activity over repeated PDH and air-regeneration cycles, explained by Zn depletion on the surface due to its diffusion into subsurface layers or the bulk. ZnxAlyO4 NPs gave a comparable initial selectivity and catalytic activity as 50ZnO/Al2O3. With time on stream, ZnxAlyO4 NPs deactivate due to the formation of coke at the catalyst surface, yet the extend of coke deposition is lower than for the ZnO/Al2O3 catalysts, and the activity of ZnxAlyO4 NPs can be regenerated almost fully using calcination in air.

Correlating the Structural Evolution of ZnO/Al2O3 to Spinel Zinc Aluminate with its Catalytic Performance in Propane Dehydrogenation

Co-precipitation was employed to synthesize Ca-based, Al2O3-stabilized sorbents for CO2 capture. The chemical composition and morphology of the synthesized sorbents were characterized using scanning electron microscopy, X-ray diffraction and N2 adsorption analysis. The cyclic CO2 uptake of the synthetic sorbent was studied in a thermo-gravimetric analyzer and compared to limestone. It was found that the calcium precursor, precipitation agent as well as the pH value at which the precipitation was performed, strongly influenced the chemical composition and morphology of the precipitated sorbents and, in turn, their cyclic CO2 uptake capabilities. Sorbents which were synthesized using Ca(NO3)2 as the calcium precursor, and precipitated with Na2CO3 at pH 7.0 showed the best cyclic CO2 uptake capability. The CO2 capture capacity of the best synthetic sorbent was 0.32 g CO2/g sorbent after 30 cycles of calcination and carbonation, which compares favourably to the CO2 uptake of limestone of 0.20 g CO2/g sorbent. Correlating the volumes in pores with pore radii narrower than 100 nn with the CO2 uptake capacity of the synthetic sorbents indicated that sorbents which possess a high pore volume equally show high CO2 uptake capabilities.

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DEVELOPMENT OF SYNTHETIC, Ca-BASED SORBENTS FOR CO2 CAPTURE USING THE CO-PRECIPITATION TECHNIQUE

Investigation of K2co3-Modified Cao Sorbents for Co2 Capture Using In-Situ X-Ray Diffraction

One of the most promising approaches for the capture of CO2 from flue gases is the use of CaO-based CO2 sorbents. For CaO-based materials, the capture and release of CO2 follows the reversible reaction: CaO(s) + CO2(g) ↔ CaCO3. However, unmodified CaO derived via calcination of naturally occurring limestone shows a rapid decay of its CO2 uptake capacity with cycle number. Here, we review fundamental aspects of the carbonation and calcination reaction, putting particular emphasis on the morphological changes of CaO over multiple carbonation–calcination cycles. Subsequently, recent attempts to develop synthetic CaO-based CO2 sorbents, viz. unsupported CaO derived via the calcination of complex calcium precursors and CaO supported on a high Tammann temperature (temperature at which sintering starts) matrix, which substantially exceed the cyclic CO2 capture capacity of limestone, are presented.

Synthetic calcium oxide-based carbon dioxide sorbents for calcium looping processes

In chemical looping, Fe-containing oxygen carriers can catalyze as a side reaction the decomposition of methane, which results in the deposition of carbon on their surface with multiple adverse effects. In this work, we propose a strategy to reduce the extent of carbon deposition by using Co as a second redox-active metal that forms a bimetallic phase with Fe during reduction. We show for a perovskite-based oxygen carrier that the formation of the bimetallic Fe–Co phase improves the dispersion and decreases the size of iron within the material, which may influence its catalytic effect on the decomposition of methane (in addition to potential changes in its electronic structure). 

Agnieszka M. Kierzkowska

Papers

Correlating the Structural Evolution of ZnO/Al2O3 to Spinel Zinc Aluminate with its Catalytic Performance in Propane Dehydrogenation

DEVELOPMENT OF SYNTHETIC, Ca-BASED SORBENTS FOR CO2 CAPTURE USING THE CO-PRECIPITATION TECHNIQUE

Investigation of K2co3-Modified Cao Sorbents for Co2 Capture Using In-Situ X-Ray Diffraction

Synthetic calcium oxide-based carbon dioxide sorbents for calcium looping processes

Chemical Looping Partial Oxidation of Methane: Reducing Carbon Deposition through Alloying