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Page 2 of 21 Sun et al. Microstructures 2023;3:2023032 https://dx.doi.org/10.20517/microstructures.2023.32

the atmosphere, with its warming effect accounting for about 60% of the total warming effect among all
[5,6]
greenhouse gases . Therefore, it is urgent to work out an environment-friendly CO capture technology to
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alleviate the greenhouse effect .
[7,8]
In recent years, the development of carbon capture and separation (CCS) technology has attracted social
attention. Adsorbents that can be used for CO capture include activated carbon, zeolite, alumina, metal
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oxides (CaO, MgO, K O, Li O), metal-organic frameworks (MOFs), and other surface-modified porous
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media [9-12] . Compared to traditional inorganic porous materials, MOFs have many advantages and show
great application potential in CO adsorption and sequestration. One is the modifiability of its secondary
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building units (SBUs) and organic ligands. Through the modification of inorganic/organic nodes on
functionality groups, the fine-tuning of the pore size and channel environment in MOFs can be precisely
achieved, and then MOFs oriented to CO capture can be synthesized [13-15] . On the other hand, due to their
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high density of active sites, high stability, and rich topological structures, MOFs have distinct advantages,
such as mild reaction conditions and easy adsorption and sequestration of CO 2 [16-18] .

A large number of relevant papers and reviews have been published [19,20] . In contrast to the published
reviews, this paper presents the current CO capture technology and related adsorbents. Then, the
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parameters for evaluating the performance of CO capture adsorbents are presented to achieve the best
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capture capacity and reduce costs and energy expenditure. In addition, recent advances in MOF-based CO
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capture methods and ways to improve the capture performance of the materials are explored. The strategies
and methods described in this review will not only provide new propositions for the construction of
CO -oriented capture MOFs but also contribute to the mitigation of industrial consumption to achieve
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carbon neutrality and thus slow down the process of global warming.

CO CAPTURE
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In September 2020, the “Address at the General Debate of the 75th Session of the United Nations General
Assembly” and the “Address at the United Nations Biodiversity Summit” proposed that China should aim
to achieve CO peak emissions by 2030 and carbon neutrality by 2060. In addition, many countries around
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the world have enacted policies or legislation to advance the goal of carbon neutrality. So far, 29 countries
and regions have pledged to be carbon neutral . The prevailing view is that CCS may be the cheapest
[21]
technology to reduce emissions in the long term and will gain time to develop new technologies such as
alternative energy sources [22,23] .

CO capture technology
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CCS technology refers to the separation of CO from industrial and energy-related production activities and
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its long-term sequestration in natural underground reservoirs in order to reduce CO emissions to the
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atmosphere [24,25] . There are three main components to CCS technology: (1) CO capture from fixed carbon
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sources (e.g., power plants); (2) CO compression and transport; and (3) CO storage.
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In terms of the capture process, there are three main types of CO capture technologies: pre-combustion
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capture, post-combustion capture, and oxy-fuel combustion [Figure 1]. Pre-combustion capture uses new
[26]
gasification technology to convert fossil fuels into H and CO , which are then captured before combustion.
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Compared with direct coal combustion, this technology has higher fossil fuel utilization, less waste disposal,
and less water consumption. In addition, due to high CO /H gas pressure and CO concentration, the
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energy consumption of pre-combustion CO capture is only 10%-16% of the total energy consumption,
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which is about half of the energy consumption of post-combustion capture. However, the high energy
consumption of the fuel conversion step limits its further development [27-29] . Oxy-fuel combustion is based