CO2 Absorption Made Easier

Researchers at the Georgia Institute of Technology (GIT) have discovered a new material capable of absorbing carbon dioxide (CO2) from the smokestacks of coal-fired power plants and other generators of greenhouse gases. According to the scientists, the new substance, which is formally known as “hyperbranched aluminosilica” (HAS), can be produced in a simple and cost-effective chemical process. Moreover, the material can be used repeatedly, and when combined with novel heat management techniques, can absorb large quantities of carbon dioxide from coal-burning facilities.
 Georgia Tech graduate student Jeffrey Drese displays a tubular reactor filled with the HAS adsorbent dispersed in sand. The reactor will be used to test the new material for its ability to capture carbon dioxide. (Georgia Tech Photo: Gary Meek)
Georgia Tech graduate student Jeffrey Drese
displays a tubular reactor filled with the
HAS adsorbent dispersed in sand. The reactor
will be used to test the new material for
its ability to capture carbon dioxide.
(Credit: Georgia Tech/Gary Meek)

With the new material, the GIT team has overcome two main obstacles facing developers of carbon absorption techniques – the lack of stability in solid materials often limits them to a one-time use, while the liquid absorbents are expensive and require a lot of energy. “This is something that you could imagine scaling up for commercial use,” said Christopher Jones, a Professor in the School of Chemical and Biomolecular Engineering at the Georgia Institute of Technology. “Our material has the combination of high capacity, easy synthesis, low cost, and a robust ability to be recycled – all the key criteria for an adsorbent that would be used on an industrial scale.”

The research, which was conducted in collaboration with the U.S. Department of Energy, provides a method that uses covalent bonding to add C02-absorbing amine polymer groups to a solid silica substrate. Due to the strength of these chemical bonds, the material can withstand multiple cycles of usage. “Given the volumes involved, you must be able to recycle the adsorbent material for the process to be cost-effective,” said Jones. “Otherwise, you would be creating large and expensive waste streams of adsorbent.”
The production of HAS requires a relatively simple process, in which the silica substrate is mixed with a precursor of the amine polymer in solution; the amine polymer is initiated on the silica surface, producing a solid material that can be filtered out and dried. The researchers tested the new material by passing simulated flue gases through tubes containing a mixture of sand and HAS. The findings showed that CO2 is absorbed at temperatures ranging from 50 to 75 degrees Celsius. HAS must then be heated to 100-120 degrees Celsius to drive off the gas in order to be used again.  The scientists performed as many as twelve absorption-desorption cycles, measuring no significant losses in capacity.

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Since the process of CO2 absorption generates considerable amounts of heat, it is imperative to develop efficient heat management and thermal recycling techniques. “How to manage this heat is one of the most critical issues controlling the economics of a potential large scale process,” Jones added. “You must control the production of heat by the adsorption step, and you don’t want to put any more energy into the desorption process than necessary.”

 Georgia Tech graduate student Jeffrey Drese assembles a fixed-bed flow system by loading a tubular reactor into a heating chamber. The equipment is used to test the new adsorbent material. (Georgia Tech Photo: Gary Meek)
Georgia Tech graduate student
Jeffrey Drese assembles a
fixed-bed flow system by loading
a tubular reactor into a
heating chamber.
The equipment is used to test
thenew adsorbent material.
(Credit: Georgia Tech/Gary Meek)

According to the researchers, further improvements of the material and other components of the separation and sequestration process must be made before the technique can become practical for removing CO2 from flue gases. “There are many pieces that must fit together to make the overall economics of carbon dioxide capture and sequestration work,” Jones added. “The biggest challenge for this whole field of research right now is to do this as inexpensively as possible. We think that our class of materials – a hyperbranched amine polymer bound to a solid support – is potentially ideal because it is simple to make, reusable and has a high capacity.”
in an article which provides an overview of many efficient and eco-friendly techniques used in modern computing industry.TFOT has previously covered a number of innovative “green” technologies including “Carbon Hero” – a device, which by tracking users’ traveling distance, enables them to keep track of their carbon dioxide generation. TFOT also covered the topic of “green computing”, in an article which provides an overview of many efficient and eco-friendly techniques used in modern computing industry.

More information on the newly developed material can be found here.

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