Brown and Yale Universities researchers say they have found a cheaper, more sustainable way to use CO2 to make acrylate, an important commodity chemical used to make materials from polyester fabrics to diapers.
Chemical companies churn out billions of tons of acrylate each year, usually by heating propylene, a compound derived from crude oil, Brown researchers say. Currently everything that goes into making acrylate is from relatively expensive, nonrenewable carbon sources, according to Wesley Bernskoetter, assistant professor of chemistry at Brown.
In the joint project by the two universities, researchers combined CO2 with a gas called ethylene in the presence of nickel and other metal catalysts to make the chemical. CO2 is essentially free and something the planet currently has in overabundance. Ethylene is cheaper than propylene and can be made from plant biomass, the universities say.
Researchers have been looking into the possibility of making acrylate from CO2 since the 1980s, but there has been a persistent obstacle to the approach. Instead of forming the acrylate molecule, CO2 and ethylene tend to form a precursor molecule with a five-membered ring made of oxygen, nickel and three carbon atoms (pictured). To finish the conversion to acrylate, that ring needs to be cracked open to allow the formation of a carbon-carbon double bond, a process called elimination.
That step had proved elusive. But the research by Bernskoetter and his colleagues, published in the journal Organometallics, shows that a class of chemicals called Lewis acids can easily break open that five-membered ring, allowing the molecule to eliminate and form acrylate. Lewis acids are basically electron acceptors. In this case, the acid steals away electrons that make up the bond between nickel and oxygen in the ring. That weakens the bond and opens the ring. From here, the team needs to tweak the strength of the Lewis acid used.
The ongoing research is part of a collaboration between Brown and Yale supported by the National Science Foundation’s Centers for Chemical Innovation program. The work is aimed at activating CO2 for use in making many kinds of commodity chemicals.
In September 2011, Canadian company Knowaste announced plans to build the UK’s first diaper-recycling facility as part of a £25 million ($40 million) investment in the country.
In November 2011, Kimberly-Clark signed an agreement aimed at expanding used diaper recycling program into Australia, Ireland, the UK and mainland Europe. The agreement gave the company right of first refusal to sponsor composting facilities by OCS.