Acrylics are an incredibly diverse and useful family of chemicals used in all kinds of products, from diapers to nail polish. Now a team of researchers from UConn and ExxonMobil describes a new way of their production. The new method would increase energy efficiency and reduce toxic by-products.
The global acrylic acid market is huge. The world of industry used nearly 5 million metric tons in 2013, according to the PetroChemicals Europe industrial group. And no wonder acrylics and related acrylates are building blocks for many types of plastics, adhesives, textiles, dyes, paints and papers. Turned together in long strings, they can produce all the useful materials. The acrylate blended with sodium hydroxide is, for example, superabsorbent material used in diapers. Add additional methyl groups (carbon plus three hydrogens) and acrylate forms plexiglass.
Current industrial processes for the manufacture of acrylates require high temperatures close to 450 F and produce undesirable and sometimes harmful by-products such as ethylene, carbon dioxide and hydrogen cyanide.
UConn chemist Steve Suib, director of the University Institute for Materials Engineering, and colleagues from UConn and ExxonMobil have designed a new way to produce acrylates at moderate temperatures. Their technique can be fine tuned to prevent the formation of undesirable chemicals.
"ExxonMobil Research & Engineering scientists, working with Professor Suib's group at UConn, are researching new technologies that can reduce energy intensity, skip steps, improve energy efficiency, and reduce CO2 emissions in the acrylic process," says Partha Nandi chemist at ExxonMobil. "A recent publication, Nature Communications, describes the discovery of a new way to produce a class of acrylic derivatives in potentially fewer steps and less energy."
This technique uses a porous catalyst made of manganese and oxygen. Catalysts are materials used to accelerate reactions. They often provide the surface with molecules to sit while responding to each other and assisting them to meet the correct configurations to do this. In this case the pores fill this role. The pores are from 20 to 500 Angstroms wide, large enough to get relatively large molecules. The manganese atom in the material can trade electrons with nearby oxygen, which facilitates proper chemical reactions. Depending on the starting materials, the catalyst can relieve all kinds of acrylics and acrylates with very little waste, says Suib.
"We hope it can be increased," he says. "We want to maximize yield, minimize temperature and create an even more active catalyst," which will help the reaction faster. The group also found that adding a bit of lithium helped speed things up. They are currently studying the exact role of lithium and experimenting with ways to improve manganese and oxygen catalyst.