NEW ORLEANS: A new boxed set season of Grey's Anatomy could help combat climate change according to research suggesting that waste carbon dioxide could be used to make the plastic in CDs and DVDs.

Scientists have found a new chemical pathway that turns carbon dioxide (CO2) into plastics such as polyurethane or polycarbonate, the most widely used plastics in the world, found in tennis racket grips, iPod cases, and especially CDs and DVDs.

Toshiyasu Sakakura, a chemist with the Japanese National Institute of Advanced Industrial Science and Technology in Tokyo, presented the new method last week at the annual meeting of the American Chemical Society in New Orleans, USA.

According to Sakakura, previous attempts to use CO2 to make dimethyl carbonate (DMC), a preliminary phase in the production of plastics, involved a two-step process with a liquid catalyst that had to be removed and recycled.

"As far as I know there are several processes using carbon dioxide to make cyclic carbonate [a precursor to DMC], but there is no process that makes DMC directly from carbon dioxide," said Sakakura.

So, Sakakura set out to find a new chemical technique. The result was a single-step process with a very robust solid catalyst.

Surprise catalyst

The catalyst that Sakakura created combines inorganic silica with phosphonium, which is surprising because alone, neither of them speeds up the reaction.

"When we put silica and phosphonium together we found that one plus one is not two, but equals two hundred," said Sakakura. "The combination boosts the catalytic activity much [more] than expected."

The new process has other advantages, including the fact that the raw materials can simply be placed in a tube and the product pops out the other end.

"The process is more straightforward, and another good point is it does not produce much waste," said Sakakura. "The waste is just water, so it is a simple and clean process now."

Another major advantage is that DMC is often produced using phosgene, a toxic chemical that was used in World War I as a chemical weapon. The new solid catalyst could do away with some of the millions of tonnes of phosgene produced each year for the chemical industry.

Challenges ahead

Although power stations and chemical plants are not currently forced to remove CO2 from their smokestacks, Sakakura believes that many would if there were a financial incentive such as being able to produce plastics.

The market for polymers or plastics around the world is massive. According to Thomas Muller, a chemist at the Centre for Catalysis Research in Germany who also presented on CO2 capture and storage in plastics, there were 240 million tonnes produced in 2005.

However, only a percentage of those could be made with captured CO2. And as Jeff Tester, a chemist at the Massachusetts Institute of Technology in Cambridge pointed out, "the scale is all wrong."

"The chemistry isn't wrong, and it's not that you can't do it, but what would you do with all that polycarbonate?" he said. "You'd need to do it in the gigatonnes category for carbon sequestration to do anything [to slow climate change]."

Added to that challenge, Sakakura's reaction requires methanol, a chemical commonly produced by burning coal. This could dramatically reduce the net amount of CO2 offset by the process.