Tag Archives: CO2

turner

Green Chemistry at Virginia Tech Part II

For my second interview in the Virginia Tech series, I had the privilege of interviewing Dr. Richard Turner. Like Dr. Long, he worked in the chemical industry and saw that most of the companies that practice green chemistry do so for regulatory and financial reasons. While working in the private sector Dr. Turner worked on plastics made without solvents – in ‘melt phase reactions.’ Melt phase processes eliminate energy consuming steps or the need to add something else to the waste stream.  They are inherently more environmentally friendly. They work by placing solids (which don’t react very fast) into solution so that the molecules can have the mobility to find each other and react.

In his own labs on campus, Dr. Turner has a few projects in melt phase rather than in solution as described above. His lab is also trying to make polymers that capture carbon dioxide. He describes:

“Carbon dioxide build-up in the atmosphere is going to be an increasingly large issue – we have to invest in the research now to learn how to capture and sequester the carbon dioxide. Polymer particles have huge surface areas, with ligands that can capture CO2. The sorbent (“a material used to absorb liquids or gases,” according to Wikipedia; yes, I had to look it up) and ligands capture CO2 and then moves it to reactor where it releases it, concentrating the CO2.”

Dr. Turner is also on the science advisory board of the company, Novomer, which was featured in a previous article on converting oranges to plastic. He works on biodegradability and reducing the overall energy footprint. “We have to make sure we do really tough and detailed analysis of our choices.”

In the classroom, Dr. Turner teaches a course called: “Future Industrial Professionals in Science and Engineering”. The course caters to scientists and engineers who want to go into industry. He divides the class into groups who run individual projects; this year all the projects were sustainability driven. There were three projects in total: the first worked to extend the shelf life of food; the second worked to improve battery life; the third worked to make a better membrane for reverse osmosis.

Outside of his own class, Dr. Turner was impressed with Tech’s sustainability. He discussed the accomplishments of the College of Natural Resources and the Environment, while also noting the strong Renewable Resources Group.

AGC applauds Dr. Turner’s hard work with sustainable chemistry, and hopes it serves as inspiration to other chemists.

 

Oranges to Plastic

Green Chemistry: Oranges to epoxide to polymer to plastic?

Lately we have been reading the green chemistry headlines about turning orange into plastic. But what does this really mean? What is the chemistry behind it? How does my orange peel become plastic? Read more for answers:

 

Step 1: Why oranges? Orange rinds have a ringed compound called limonene that gives citrus fruits their smell.

 

Above is the structure of limonene, courtesy of toxipedia.

 

Step 2: The limonene can be turned into an epoxide with the addition of an oxygen atom.

 

Above is the structure of limonene oxide, with the epoxide structure shown in red. Image courtesy of Santa Cruz Biotechnology.

 

The compound from step 2 is not very unstable since the epoxide structure (as seen in red) has angular strain and potential strain from sterics (having many components of a structure taking up the same space and being too close to one another). The epoxide creates bond angles that are not ideal as they are too small. The small bond angles are unstable and reactive – doing whatever they can to remove that strain.

 

Step 3: This is where carbon dioxide comes in. With the help of a zinc complex as a catalyst, the CO2 reacts with the epoxide structure to relieve the strain, allowing the epoxide to react with other epoxides to produce a polymer structure. This polymer structure is called polylimonene carbonate.

 

Step 4: Now we have a polymer (a compound with repeating units) which can be used to make plastic products through research and design. Currently there are no products on the market using this technology, but we hope to see that change in the near future!

 

Reaction is described as seen in JACS.

 

Power plant exhaust recycled in the lab.

Synopsis by Wim Thielemans, Oct 25, 2011

Stevens, JG, P Gomez, RA Bourne, TC Drage, MW George and M Poliakoff. 2011. Could the energy cost of using supercritical fluids be mitigated by using CO2 from carbon capture and storage (CCS)Green Chemistry http://dx.doi.org/10.1039/c1gc15503b.

The potential to reuse captured carbon dioxide from power plant exhaust/emissions as a mixer for other chemical reactions is shown in a unique study.

In the future, coal and natural gas fired power plants may be able to provide an abundant supply of liquid carbon dioxide (CO2) – a valuable agent used in chemical reactions in a growing number of industrial applications.

A preliminary study of this unique way to recycle and reuse carbon dioxide finds the main impurities in the power plant CO2 won’t prohibit its commercial use. The results are explained in the journal Green Chemistry.

Carbon dioxide is commonly known as the greenhouse gas formed by burning fossil fuels. Energy producers intend to capture and store the carbon dioxide they produce. To do this, they’ll convert the CO2 gas into its supercritical state – that is, changing the gas into a liquid by using extreme heat and pressure.

Converting carbon dioxide gas into a liquid is one way power plants can meet the anticipated tougher emissions standards in an effort to counteract climate change. As a liquid, carbon dioxide is also a safe solvent in other chemical production processes. It has already found applications in decaffeinating coffee and in dry cleaning.

A main advantage of supercritical carbon dioxide is that it helps produce a purer end product without toxic residue. In a typical chemical reaction with it, lowering the pressure at the end of the reaction turns the supercritical carbon dioxide fluid back into a gas. The chemical product produced during the reaction is immediately recovered. If all starting material is converted to the final product, no further purification of the end product is needed.

The supercritical state is reached by heating and compressing carbon dioxide to above its critical point of 88oF and 1071 pounds per square inch (psi). Supercritical fluids behave as liquids for dissolving chemicals but allow the chemicals to move around at high speeds as they would in gases.

Unfortunately, compressing carbon dioxide to above its critical point is energy-intensive. This makes it usually too costly for industrial-scale reactions.

However, coal and natural gas fired power plants provide a cheap source of compressed carbon dioxide. To reduce their carbon dioxide emissions, energy producers intend to capture and store the carbon dioxide they produce. Because large power plants easily produce more than half a ton of carbon dioxide per second, compressing it reduces the required space for storage. It is this compressed carbon dioxide that could be used as a solvent in industrial processes.

Researchers in the United Kingdom investigated the effect of impurities found in carbon dioxide from power plants on a chemical reaction. They tested the supercritical carbon dioxide in a reaction at a modern industrial production facility. The facility does not use supercritical carbon dioxide because the high compression costs proved uneconomical.

In this work, none of the major impurities – nitrogen, water and carbon monoxide – posed insurmountable problems at the concentration likely to be found in power plant exhaust. Water and carbon monoxide did reduce the activity of the catalyst metal used to speed up the reaction. Increasing the temperature restored the catalyst’s activity.

This work is very relevant to industry and is a very promising first step toward reusing captured carbon dioxide. But, as the authors pointed out, it is only preliminary, and only one reaction was studied. Also, many impurities found in power plant carbon dioxide in very small quantities were not investigated.

Read more science at Environmental Health News.

 

Include key green chemistry ideas when covering polymer science.

Posted by Wim Thielemans, Sep 28, 2011

A recent article in Chemical & Engineering News leaves out key points reporters should include when explaining the pitfalls for new polymers vying for market share.

A cover story in Chemical & Engineering News describes a variety of new polymers – commonly called plastics – that are vying for current market share in a crowded field. Author Alexander H. Tullo focuses on how companies are avoiding the pitfalls of previous attempts to break into markets dominated by the long-used polymers – such as polyethylene, polypropylene and nylon – that were developed prior to 1960.

The long article covers a lot of ground but misses some important aspects of materials science and green chemistry, which should also be considered.

Tullo expertly describes a variety of polymers with varying chemical properties. He clearly states the market potential of these polymers, emphasizing their improved properties. While this is obviously important, cost  – especially for bulk polymer applications – is not mentioned. Many new polymers tend to be more expensive than those currently used. Existing polymers tend to be cheaper because of economies of scale – larger volumes are cheaper to produce. Yet, producing large amounts at a reasonable price is a major hurdle for new polymers in trying to find inroads to these low-cost and high-volume applications.

The author did not specifically mention which markets would be the most receptive to the new polymers. Yet, the examples clearly show that niche, high-value and new-technology applications present the most important inroads. This is especially true where existing polymers do not do a perfect job and improvement is easily achieved.

Some final hints may help journalists to collect and report more detailed information on the environmental impact of materials. As an example, the environmental benefit of the Novomer polymer mentioned in the article is extraordinary. It is a real feat to make a polymer with 40 percent of its total weight derived from carbon dioxide (CO2), which is removed from the atmosphere to make the polymer.

Reporters, though, need to dig deeper and ask about key points to help readers better understand a product’s overall impact. For example, if a point is made about removing CO2 from the atmosphere, ask how much material needs to be made to sequester the CO2 from a single power plant’s emissions, whether there is a market for all the material and whether the chemical reaction to make the polymer could cope with the quantities and required reaction rates to keep up with CO2 supply.

If environmental benefits are mentioned, ask for life cycle analysis results. Life cycle analyses describe the start-to-finish environmental effects from making a material to disposing of the finished product. The analysis results will make it clear if a real environmental benefit exists. Also, ask whether the preparation of the material conforms to the Principles of Green Chemistry. In the case of the Novomer polymer, the use of ethylene oxide – a well-known neurotoxin – in the polymer preparation would certainly raise questions about its environmental credentials.

The article is very interesting and an enjoyable read, but is at times rather narrowly focused. I would have liked the author to more broadly question the reasons why new polymers have such a difficult time entering and expanding into the marketplace.

Read more science at Environmental Health News.

 

Carbon dioxide can be a chemical building block.

Synopsis by Evan Beach, Mar 17, 2011

Beckman, EJ, and P Munshi. 2011. Ambient carboxylation on a supported reversible CO2 carrier: ketone to b-keto ester. Green Chemistry http://dx/doi.org/10.1039/c0gc00704h.

Laboratory trials of a coated silicone material may pave the way for the use and reuse of carbon dioxide in the chemical industry. Carbon dioxide can be used as a raw material for ingredients found in pharmaceuticals, pesticides and other specialty chemical products. The landmark process is explained in a recent article in the journal Green Chemistry.

The discovery won’t significantly impact global carbon dioxide emissions, but it will make it easier for chemists to work with an inexpensive, abundant source of carbon that’s widely available as a waste material.

Carbon dioxide has been widely used in the preparation of larger molecules, but the need for high pressure to make the reactions go is a major limitation. The scientists found that by using a specially designed carrier material, carbon dioxide can be used at room pressure.

The carrier material is based on silicone with a permanent chemical coating that absorbs the carbon dioxide. The carbon dioxide binds at room temperature, but is only released if the material is heated to 120 degrees Celsius (about 250 F). These properties allow the bound carbon dioxide to be used within a wide range of temperatures.

The material can be easily separated from reaction mixtures, making it easy to purify the chemical products. This represents a major improvement over liquid-based carbon dioxide absorbents, which require extra steps to separate. The solid carrier is also easily recycled: the researchers saw no loss of activity after five cycles of carbon dioxide binding and release.

The material was tested for its ability to promote chemical reactions that add carbon dioxide to other molecules. Good efficiency was found at room temperature and pressure. No silicon was found in the chemical products, indicating that the carrier material is very stable.

The researchers also showed the carrier material could improve the reactivity of other molecules besides carbon dioxide, so it could be more widely useful. Future work might explore a wider variety of carbon dioxide chemistry, including manufacturing of plastics.

Carbon-absorbent foam triumphs at 2010 Earth Awards

By Shanta Barley, guardian.co.uk

Thursday 16 September 2010

The Earth Awards: Revolutionary artificial foam
A revolutionary artificial foam which captures and converts the Sun’s energy more effectively than living organisms has won the Earth Awards 2010. Illustration: The Earth Awards

An artificial foam inspired by the meringue-like nest of a South American frog has won the 2010 Earth Awards. The foam, which could help to tackle climate change, soaks up carbon dioxide from the atmosphere and generates sugars that can be converted into biofuel.

The Earth Awards were set up in 2007 to bring together green start-ups strapped for cash with investors. Between March and May, over 500 designs were submitted to a panel of judges that included Richard Branson, Jane Goodall, David de Rothschild and Diane von Furstenberg.

The panel awarded $10,000 each to six finalists in August. Tonight, the winning design – a photosynthetic foam developed by David Wendell and Carlo Monetmagno of the University of Cincinnati – was awarded $50,000 at Marlborough House, London, as part of the Prince of Wales’ Start Festival.

The foam, which will be installed in the flues of coal-burning power plants, captures carbon dioxide and locks it away as sugar before it has a chance to enter the atmosphere and contribute to climate change. Due to its frothy structure, the foam can be up to five times more efficient than plants at converting carbon dioxide into sugar.

Wendell knows that the foam is manufacturing sugar – glucose – but he hasn’t yet managed to extract the sugar in order to convert it into biofuel. Wendell says creating a biofuel like this is desirable as it reduces the pressure to grow biofuel crops on land for crops, and keeps the price of staple foods like cereal and rice down.

The secret to the foam’s success is a protein that the Tungara frog uses as scaffolding in its foamy nests. “I read about a protein that the frog uses that allows bubbles to form in the nest, but doesn’t destroy the lipid membranes of the eggs that the females lay in the foam, and realised that it was perfect for our own foam. The foam contains a mixture of over 11 different enzymes harvested from bacteria, plants and fungi. It fixes carbon dioxide as sugars like fructose and glucose at a rate that exceeds that found in plants,” Wendell said.

According to Rick Fedrizzi, chief executive of the United States Green Building Council, one of the award judges, Wendell’s idea and those of the other finalists were “amazing but wouldn’t necessarily have seen the light of day without the Earth Awards”.

“Cash prizes are great but the real benefit of the Earth Awards is that your idea or technology is recognised by your peers,” says Fedrizzi. “Plus you get to network with venture capitalists, who might choose to invest in you at a later stage when your idea is more tangible.”

Fedrizzi’s favourite entry was the Sustainable Shell, a biodegradable home that can be built from the soil on which it sits. “You might be living in the Serengeti in Africa with access to nothing but mud and water, but by using these design principles anyone can build a strong, sustainable shelter,” he says.

Designed by Michael Ramage of the Department of Architecture at Cambridge University, the home will probably be a hit among NGOs seeking to rebuild regions like Haiti that have been devastated by natural disasters. It’s also very beautiful, says Fedrizzi: “It brings to mind centuries-old Moorish temples.”

Among the other finalists is Jamie Lim, a Malaysian ethical designer who has created a range of sunglasses hand-crafted from bamboo – a fast-growing, biodegradable and low-carbon alternative to plastic. For every pair of “KAYU” sunglasses bought, Lim donates $20 towards surgery that restores sight in the developing world.

Another design recognised by the awards was Arthur Huang’s Polli Bricks – a low-carbon form of cladding made from recycled plastic bottles that can be wrapped around buildings to insulate them. They come studded with solar-power LED lights and cost around ten times less than conventional cladding.

Not all of the entries into the Earth Awards were tangible structures, however. The Biomimicry Institute in Missoula, Montana, submitted Ask Nature – an open source digital library that allows people to find out how nature has solved problems that now confront humanity.

See original article here.

Dream of plastics from carbon dioxide is a reality.

Dream of plastics from carbon dioxide is a reality.

Jun 01, 2010

Zhang, Y and J Young Gerentt Chan. 2010. Sustainable chemistry: imidazolium salts in biomass conversion and CO2 fixation. Energy and Environmental Science http://dx.doi.org/10.1039/b914206a.

Synopsis by Adelina Voutchkova
Certain classes of organic molecules can be instrumental in both capturing carbon dioxide from the air and incorporating it into new plastic materials, which could lessen the need for raw petroleum.

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Chemists have made progress in finding environmentally friendly ways to capture and reuse carbon dioxide (CO2). Specifically, significant new advances have been made in the ability to absorb CO2 from the atmosphere and incorporate it into new raw materials – including benign alternatives to BPA-based plastics.

Certain classes of organic molecules have been discovered to be instrumental in capturing carbon dioxide from the air and incorporating it into new plastic materials. This process eliminates petroleum as an input, and generates more benign materials in the process.

In this and several other recent articles, researchers report how a class of chemicals – called “ionic liquids” – can efficiently capture and incorporate CO2 into chemicals, which can then be turned into a plastic. Such plastics can contain about 40 percent by weight of incorporated CO2.

CO2 is an excellent chemical building block; it is renewable, abundant and considered environmentally friendly. Plants efficiently convert CO2 into food through photosynthesis. Scientists, however, have long struggled to reproduce this process at an industrial scale. Before recent advances, the methods that existed were very inefficient, rendering them economically unviable.

Two research groups may have stumbled on a much more efficient method. Using chemicals called imidazoliums and N-heterocyclic carbenes (NHCs), researchers in Singapore report they were able to couple CO2 with molecules called “epoxides” to form polycarbonates – plastics used in everything from water bottles to compact disks. Importantly, in addition to finding a new use for carbon dioxide, these polycarbonates do not contain bisphenol A. It turns out that while virtually all commercial polycarbonate plastics today are made using bisphenol A as the basic building block, there are alternatives, as demonstrated by this research.

The imidazolium salts are stable chemicals that can repeatedly “grab” CO2 molecules and hand them over to be incorporated into bigger molecules. This makes them valuable in processes that convert CO2 to other chemical products as well. In addition, they are more benign and the reactions less severe than the metals typically used.

In sum, this research demonstrates two significant advances, first in demonstrably moving forward the capacity to harness and use CO2 in industrial applications, second in its successful application in developing a benign alternative to a problematic chemical.

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1 June Dream of plastics from carbon dioxide is a reality. Chemists have made progress in finding environmentally friendly ways to capture and reuse carbon dioxide. New advances have been made in the ability to absorb CO2 from the atmosphere and incorporate it into new raw materials – including benign alternatives to BPA-based plastics. Environmental Health News.

16 December How to make plastic with less petroleum–just add CO2. Using technology developed at Cornell University, Novomer gets additional funding to develop a plastic-manufacturing process that requires less oil by folding in carbon dioxide. Scientific American.

10 April New process converts C02 into plastic products. If plans to remove carbon dioxide–the primary greenhouse gas –from smokestacks succeed, the gas could be harnessed and turned into plastic products, new research claims. Xinhua News Agency, China.

9 April CDs and DVDs to be made with CO2 emissions. Scientists have devised a new way to enable pop groups and film stars with a conscience to save the planet: Their CDs and DVDs can now be made from carbon dioxide. London Daily Telegraph, United Kingdom.

6 May What can we do with carbon dioxide? Scientists are trying to find ways to convert the plentiful greenhouse gas into fuels and other value-added products, some saying that target areas should focus on using CO2 to replace large-volume starting materials derived from petroleum and natural gas. Chemical & Engineering News.