The global market for acrylic acid is enormous. Back in 2013, the world used close to five million metric tonnes of it, according to industry group PetroChemicals Europe. And no wonder – for acrylics and the closely related acrylates are the building blocks for many kinds of plastics, glues, textiles, dyes, paints, and papers.
Strung together in long chains, they can make all kinds of useful materials. Acrylate mixed with sodium hydroxide, for example, makes a super absorbent material used in diapers. Add extra methyl groups and acrylate makes plexiglass.
Yet, current industrial processes for making acrylics require high temperatures close to 450°F, and produce unwanted and sometimes harmful by-products, such as ethylene, carbon dioxide, and hydrogen cyanide.
But now, a team of researchers from the University of Connecticut, US, and ExxonMobil describe a new process for making acrylics that could increase energy efficiency and reduce toxic by-products.
Steve Suib, a chemist at the University of Connecticut and director of the university’s Institute for Materials Science, along with colleagues from the university and ExxonMobil have designed a new way of making acrylics at mild temperatures. Their technique can be finely tuned to avoid producing unwanted chemicals.
“Scientists at ExxonMobil Research and Engineering, partnering with professor Suib’s group in UConn, have been probing new technologies that can lower energy intensity, skip steps, improve energy efficiency, and reduce CO2 footprint in the production process of acrylics,” says Partha Nandi, a chemist at ExxonMobil.
“The recent publication in Nature Communications describes the discovery of a new route to produce a class of acrylate derivatives in potentially fewer steps and with less energy.”
The technique uses a porous catalyst made of manganese and oxygen – catalysts are materials used to speed up reactions.
Often, they provide a surface for the molecules to sit on while they react with each other, helping them to meet up in the right configurations to do the deed. In this case, the pores fill that role. The pores are 20-500 Angstroms wide, big enough for fairly large molecules to fit inside.
The manganese atoms in the material can trade their electrons with nearby oxygens, which makes it easier for the right chemical reactions to happen.
Depending on the starting ingredients, the catalyst can facilitate all different kinds of acrylics and acrylates, with very little waste.
“We hope this can be scaled up,” Suib says. “We want to maximise yield, minimise temperature, and make an even more active catalyst that will help the reaction go faster.”
The group also found adding a little bit of lithium helped speed things up, too. The researchers are currently studying the exact role of lithium and experimenting with ways of improving the manganese and oxygen catalyst.
This research was funded by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical, Biological, and Geological Sciences under grant DE-FG02-86ER13622.A000, as well as ExxonMobil.
The report was published in the 8 February 2019 issue of Nature Communications.
