1) Zeolitic imidazolate frameworks (ZIFs) are metal-organic crystals that can selectively capture and store carbon dioxide. One litre of ZIF crystals can store about 83 litres of CO2. 2) The ZIF crystals are non-toxic, require little energy to produce, and are stable at high temperatures and when boiled in water or solvents, making them suitable for carbon capture at power plants. 3) Scientists at UCLA created 25 different ZIF structures that selectively capture carbon dioxide, demonstrating their potential for safely trapping industrial CO2 emissions.

1. Zeolitic imidazolate frameworks (ZIF) are one kind of metal-organic frameworks'
subsidiaries which could be used to keep industrial emissions of carbon dioxide out of the
atmosphere. One litre of the crystals could store about 83 litres of CO2. The crystals are non-
toxic and require little energy to create, making them an attractive possibility for carbon
capture and storage. "The porous structures can be heated to high temperatures without
decomposing and can be boiled in water or solvents for a week and remain stable, making
them suitable for use in hot, energy-producing environments like power plants."[1]
"Twelve zeolitic imidazolate frameworks (ZIFs; termed ZIF-1 to -12) have been synthesized
as crystals by copolymerization of either Zn(II) (ZIF-1 to -4, -6 to -8, and -10 to -11) or
Co(II) (ZIF-9 and -12) with imidazolate-type links. The ZIF crystal structures are based on
the nets of seven distinct aluminosilicate zeolites: tetrahedral Si(Al) and the bridging O are
replaced with transition metal ion and imidazolate link, respectively. In addition, one
example of mixed-coordination imidazolate of Zn(II) and In(III) (ZIF-5) based on the garnet
net is reported. Study of the gas adsorption and thermal and chemical stability of two
prototypical members, ZIF-8 and -11, demonstrated their permanent porosity (Langmuir
surface area = 1,810 m2/g), high thermal stability (up to 550°C), and remarkable chemical
resistance to boiling alkaline water and organic solvents."[2]
Like zeolites and other porous materials, zeolitic imidazolate framework membranes can be
used for the separation of gases because of its highly porous structure, large accessible pore
volume with fully exposed edges and faces of the organic links, pore apertures in the range of
the kinetic diameter of several gas molecules, and high CO2 adsorption capacity. ZIF-8
membranes display high CO2 permeances for equimolar mixtures of CO2 and CH4."[3]
New materials can selectively capture CO2,
scientists say
Last Updated: Friday, February 15, 2008 | 12:48 PM ET
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Piping carbon back into the ground
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Scientists have created metal-organic crystals capable of soaking up carbon dioxide gas like a
sponge, which could be used to keep industrial emissions of the gas out of the atmosphere.
Chemists at the University of California Los Angeles said the crystals — which go by the
name zeolitic imidazolate frameworks, or ZIFs — can be tailored to absorb and trap specific
molecules.
An optical photograph of crystals of zeolitic imidazolate
frameworks (ZIFs). The porous materials can be designed to soak up specific molecules, such
as carbon dioxide, making them potentially useful to trap the greenhouse gas. (Omar Y.
Yaghi/Science)
"The technical challenge of selectively removing carbon dioxide has been overcome," said
UCLA chemistry professor Omar Yaghi in a statement.
"Now we have structures that can be tailored precisely to capture carbon dioxide and store it
like a reservoir, as we have demonstrated. No carbon dioxide escapes. Nothing escapes —
unless you want it to do so. We believe this to be a turning point in capturing carbon dioxide
before it reaches the atmosphere."
Yaghi and his colleagues describe their findings in the Friday issue of the journal Science.
Little energy needed to create crystals
He said the crystals are non-toxic and would require little extra energy from a power plant,
making them an ideal alternative to current methods of CO2 filtering. The porous structures
can be heated to high temperatures without decomposing and can be boiled in water or
solvents for a week and remain stable, making them suitable for use in hot, energy-producing
environments like power plants.

3. The team of scientists created 25 ZIF crystal structures in a laboratory, three of which showed
a particular affinity for capturing carbon dioxide. The highly porous crystals also had what
the researchers called "extraordinary capacity for storing CO2": one litre of the crystals could
store about 83 litres of CO2.
The researchers created all 25 crystals by combining their raw materials in thousands of
chemical reactions, which they say is similar to the high-throughput methods used in
pharmaceutical research.
As concern over climate change grows and its link to human-made carbon dioxide emissions
becomes clearer, governments and businesses around the world are investigating carbon-
capturing technologies.
Past estimates from United Nation's energy and climate experts have pegged the cost of
capturing CO2 between $25 US and $60 US a tonne for conventional coal-fired plants.
Earlier this month, a task force established by the Alberta and federal governments issued a
report calling for $2-billion to get five new carbon capture and storage facilities operating by
2015.