Carbon Dioxide Capture DOI: 10.1002

Carbon Dioxide Capture DOI: 10.1002/anie.201000431
Carbon Dioxide Capture: Prospects for New Materials
Deanna M. DAlessandro,* Berend Smit,* and Jeffrey R. Long*
Angewandte Chemie
Keywords:
absorbents · adsorption · carbon dioxide ·
membranes ·
metal–organic frameworks
Reviews D. M. D’Alessandro et al.
6058 www.angewandte.org 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Angew. Chem. Int. Ed. 2010, 49, 6058 – 6082
1. Introduction
The prospect of a worsening climatic situation due to
global warming is a subject of widespread public concern,
with annual global emissions of CO2 having escalated by
approximately 80% between 1970 and 2004.[1] This drastic
rise has been attributed to an increasing dependence on the
combustion of fossil fuels (coal, petroleum, and natural gas)
which account for 86% of anthropogenic greenhouse gas
emissions, the remainder arising from land use change
(primarily deforestation) and chemical processing.[2]
The urgent need for strategies to reduce global atmospheric
concentrations of greenhouse gases has prompted
action from national and international governments and
industries, and a number of high-profile collaborative programs
have been established including the Intergovernmental
Panel on Climate Change (IPCC), the United Nations
Framework Commission on Climate Change, and the
Global Climate Change Initiative. The capture and sequestration
of carbon dioxide—the predominant greenhouse
gas—is a central strategy in these initiatives, as it offers the
opportunity to meet increasing demands for fossil fuel energy
in the short- to medium-term, whilst reducing the associated
greenhouse gas emissions in line with global targets.[3] Carbon
capture and storage (CCS) schemes embody a group of
technologies for the capture of CO2 from power plants,
followed by compression, transport, and permanent storage.
CCS will complement other crucial strategies, such as
improving energy efficiency, switching to less carbon-intensive
fuels such as natural gas and phasing in the use of
renewable energy resources (e.g., solar energy, wind, and
biomass).
A critical point is that the deployment of CCS schemes is a
multifaceted problem that requires shared vision and worldwide
collaborative efforts from governments, policy makers
and economists, as well as scientists, engineers and venture
capitalists. From this perspective, it is apparent why the
problem of CO2 capture is regarded as one of the grand
challenges for the 21st century.[3]
A number of recent high-profile reports and comprehensive
articles have considered the engineering feasibility and
economics of CO2 capture, and have sought to estimate the
costs by modeling reference cases of existing postcombustion
capture in coal- and gas-fired power plants.[3–5] Such conventional
technologies for large-scale capture have been commercially
available for over 50 years and are focused on the
separation of CO2 from flue gases by the use of amine
absorbers (“scrubbers”) and cryogenic coolers.[6]
The IPCC estimates that CO2 emissions to the atmosphere
could be reduced by 80–90% for a modern conventional
power plant equipped with carbon capture and storage
technology.[7] A recent analysis has shown that the thermodynamic
minimum energy penalty for capturing 90% of the CO2
from the flue gas of a typical coal-fired power plant is
approximately 3.5% (assuming a flue gas containing 12–15%
CO2 at 40 8C).[8] By comparison, conventional CO2 capture
using amine scrubbers will increase the energy requirements
From the Contents
1. Introduction 6059
2. Conventional Chemical
Absorption 6062
3. Emerging Methods for CO2
Capture 6063
4. New Materials for CO2 Capture 6064
5. Future Prospects 6078
The escalating level of atmospheric carbon dioxide is one of the most
pressing environmental concerns of our age. Carbon capture and
storage (CCS) from large point sources such as power plants is one
option for reducing anthropogenic CO2 emissions; however, currently
the capture alone will increase the energy requirements of a plant by
25–40%. This Review highlights the challenges for capture technologies
which have the greatest likelihood of reducing CO2 emissions
to the atmosphere, namely postcombustion (predominantly CO2/N2
separation), precombustion (CO2/H2) capture, and natural gas
sweetening (CO2/CH4). The key factor which underlies significant
advancements lies in improved materials that perform the separations.
In this regard, the most recent developments and emerging concepts in
CO2 separations by solvent absorption, chemical and physical
adsorption, and membranes, amongst others, will be discussed, with
particular attention on progress in the burgeoning field of metal–
organic frameworks.
[*] Dr. D. M. D’Alessandro
School of Chemistry, The University of Sydney
Sydney, New South Wales 2006 (Australien)
E-mail: deanna@chem.usyd.edu.au
Prof. B. Smit
Department of Chemical Engineering
University of California, Berkeley
Berkeley, CA 94720-1460 (USA)
E-mail: Berend-Smit@berkeley.edu
Prof. B. Smit, Prof. J. R. Long
Department of Chemistry
University of California, Berkeley
Berkeley, CA 94720-1460 (USA)
Fax: (+1) 510-643-3546
E-mail: jrlong@berkeley.edu
Carbon Dioxide Capture Angewandte Chemie
Angew. Chem. Int. Ed. 2010, 49, 6058 – 6082 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 6059
of a plant by 25–40%.[7–9] Other recent cost analysis estimates
based on near-term conventional regenerative amine scrubbing
systems have predicted an increased cost of electricity of
$0.06 kWh, or an “avoided cost of capture” of $57–60/tonne
CO2 (as an alternative measure).[8] Clearly, the existing
methods of capture are energy intensive and are not costeffective
for carbon emissions reduction.[7] These economic
and energy comparisons underscore the immense opportunities
and incentives that exist for improved CO2 capture
processes and materials.
Various components of the CCS process chain including
compression, transportation (by pre-existing pipelines for
instance), and storage of CO2 are technologically mature and
available, and a growing number of fully integrated CCS
projects are reaching the pilot and demonstration phases prior
to commercialization. In addition to three large-scale demonstration
projects which are currently underway in Sleipner
West (Norway), Weyburn (Canada), and In Salah (Algeria),
several smaller projects have commenced on the Dutch
continental shelf (Netherlands), Snøhvit (Norway), La Barge
(Wyoming, United States), Fenn Big Valley (Canada), Ketzin
(Germany), and Schwarze Pumpe (Germany).[9–11] All of the
current projects demonstrate carbon storage or reuse in
enhanced coal-bed methane recovery schemes, although one
project at Schwarze Pumpe in Germany, captures CO2 at a
coal-based plant. A further 40 CCS projects have already
been proposed worldwide between 2008 and 2020.[11]
One explanation for the slow deployment of fully
integrated commercial CCS schemes is the considerable cost
of the capture phase, which represents approximately two
thirds of the total cost for CCS. A recent comprehensive
report on postcombustion CO2 capture technologies has
determined that the regeneration energy, followed by the
capital cost of capture-specific equipment are the two
variables contributing most significantly to the cost of CO2
capture.[8] One significant contributor to the regeneration
energy is the maximum separation efficiency which can be
achieved by a given capture material. Enhancing this
efficiency will have the greatest potential for lowering the
overall cost of capture systems in near-term,[8] with improvements
in the capture phase for new materials representing one
of the foremost challenges.[5] As shown in Figure 1, there
exists a serious need for research on innovative new materials
in order to reduce the time to commercialization.
It is evident that a consideration of the process design
economics and costs are required to assess fully the potential
of any given new material. The challenge arises due to
necessary assumptions which must be made, and the variations
in the technical characteristics (e.g. fuel used, plant
characteristics), scale and application of a given material,
which require that capital costs be balanced with the
efficiency of material. Assessing the economics of CCS is a
nontrivial task which is outside the scope of the present
article. Nevertheless, a number of groups have developed
advanced cost-analysis models, which permit a number of the
aforementioned parameters to be varied.[5]
Here, we focus on the significant challenge of CO2 capture
and highlight recent advances in materials and emerging
concepts. The emphasis is on designed materials in which a
molecular level of control can be achieved as a means of
tailoring their performance in separating relevant gas mixtures.
In this regard, particular attention is directed towards
the latest developments in CO2 separations using microcrystalline
porous solids or metal–organic frameworks. For
more in-depth discussions on materials for CO2 separations,
the reader is directed to a number of excellent authoritative
reviews in the field.[13–21] We also seek to provide some
criteria, measurement parameters and performance standards
in which materials developed in the laboratory can be
Deanna M. D’Alessandro received her PhD
in Chemistry from James Cook University
(Australia) in 2006 for which she received
the RACI Cornforth Medal and a 2007
IUPAC Prize for Young Chemists. She held a
postdoctoral position with Prof. Long at
Berkeley (2007–2009) and was a Dow
Chemical Company Fellow of the American–Australian
Association and an 1851
Royal Commission Fellow. In 2010 she will
commence a University of Sydney Research
Fellowship focusing on energy-related applications
of microporous materials.
Berend Smit received his PhD in Chemistry
from Utrecht University. From 1988 to
1997, he worked as a researcher at Shell
Research. In 1997, he returned to academia
as Professor of Chemistry at the Univ