A "sponge" that absorbs carbon dioxide

Plastics that are very similar to plastics used in food packaging could play an important role in President Obama's plan to reduce carbon dioxide emissions by 30% by 2030.

[Translation by Dr. Nachmani Moshe]
A sponge made of plastic that absorbs the greenhouse gas carbon dioxide could facilitate our transition from polluting fossil fuels to new energy sources such as hydrogen.

A plastic that is very similar to plastic materials used in food packaging could play an important role in President Obama's plan to reduce carbon dioxide emissions by 30% by 2030. The material itself could be embedded in the chimneys of power plants. The report on the material is one of nearly 12,000 presentations to be given at the 248th National Meeting and Exposition of the American Chemical Society (ACS), the world's largest scientific society.

"The main features of this polymer are its stability, its cheap production and its ability to absorb carbon dioxide in a particularly efficient manner. The material is ready and willing to function in a real-world environment," says Dr. Andrew Cooper. In the near future when fuel cell technology will be used, this adsorbent will be able to advance us significantly towards zero emission technologies."

The most common use of materials that absorb carbon dioxide is done in the context of the removal of greenhouse gas pollutants that come from the chimneys of power plants, where fossil fuels, such as coal or gas, are burned to produce electricity. However, the team of researchers plans that the adsorbent - a microporous organic polymer - that comes from other applications, will be able to reduce the contamination resulting from these gases.

The new material will be part of a new technology known as the "integrated gasification combined cycle (IGCC)" capable of converting fossil fuels into hydrogen gas. Hydrogen holds great promise for use in cars powered by fuel cells and in electricity generation facilities, since it creates almost no pollution. The new technology (IGCC) is a bridging technology designed to drive the economy based on hydrogen gas, or the transition to hydrogen fuel, while still using the fossil fuel infrastructure. However, the new technology produces a mixture of hydrogen and carbon dioxide, which must be separated.

Dr. Cooper, from the University of Liverpool, says that the sponge works best under conditions of high pressures that exist in any case during the process carried out with the help of the IGCC technology. Similar to a kitchen sponge that swells up after swallowing water, the absorbent material swells slightly when it traps carbon dioxide in tiny spaces between its molecules. When the pressure drops, explains the lead researcher, the absorbent material contracts and releases the carbon dioxide which can be collected and stored for future use, or converted directly into useful carbon compounds.

The new absorbent material, in the form of a brown, sand-like powder, is produced by connecting masses of small carbon-based molecules to form a network. The researcher explains that the inspiration to use this structure came from polystyrene, a plastic used in packaging materials and plastic foams. It is known that polystyrene is capable of adsorbing small amounts of carbon dioxide with the same adsorption action. One of the advantages of using polymers is that they are very stable. The material can be stable even when boiled in acid, proving that it can operate in the harsh conditions of power plants and their stacks where carbon dioxide absorbents are much needed. Other carbon dioxide adsorption systems - whether they consist of plastic materials or metals or in liquid form - are not as efficient as the new system.

Another advantage of the new absorbent material lies in its ability to selectively absorb carbon dioxide without also absorbing water vapor, which could damage other materials and reduce their effectiveness. The low price of the new sponge also makes it an attractive polymer. "Compared to other adsorbents, our polymers are cheap," the researcher notes, mainly due to the fact that the carbon molecules used to produce them are cheap. "And basically, they can also be reused and they have a long shelf life due to their great chemical stability."

The researchers also describe the ways in which their microporous polymer could be adapted for use in chimneys and other exhaust streams (such as car exhausts). The researcher explains that it would be quite simple to insert the adsorbing polymers into the membranes and filters that are already used today to remove carbon dioxide in the chimneys of power plants. A combination of two adsorption systems could promote better adsorption by utilizing the strengths of each of the separate systems, explains the lead researcher.

The news about the study