Researchers break down plastic waste under mild conditions

Japanese researchers have developed a highly efficient catalyst for breaking resistant chemical bonds, paving the way for easier recycling of plastic waste.

According to the study, organometallic ruthenium catalysts may break down even the toughest amide bonds effectively under mild conditions. Catalysts are widely used in chemistry to help speed up reactions, but breaking the kinds of amide bonds in plastics, such as nylon, and other materials require harsh conditions and large amounts of energy.

Lead author Takashi Miura from Nagoya University said that this new ruthenium catalyst can hydrogenate difficult substrates under much milder conditions.

Hydrogenation is the key step leading to breakdown of amide bonds. The catalyst features a ruthenium atom supported in an organic framework. This ruthenium atom can adsorb hydrogen and deliver it to the amide bond to initiate the breakdown. The team probed the position of hydrogen on the catalyst in the reaction pathway and modified the shape of the supporting framework.

By making sure that the hydrogen molecule was is the best possible position for interaction with amide bonds, the team achieved much more effective hydrogenation.

Group leader Susumu Saito stated that the changes their team made to the catalyst, allowed some tricky amide bonds to be selectively cleaved for the first time.

This catalyst has great potential for making designer peptides for pharmaceutics and could also be used to recover materials from waste plastics to help realise an anthropogenic chemical carbon cycle, Saito explained.