Acrylic is an incredibly diverse and useful family of chemicals used in all kinds of products, from diapers to nail polish. Now a team describes researchers from UConn and ExxonMobil a new process for making them. The new method will increase energy efficiency and reduce toxic by-products.
The global market for acrylic acid is huge. The world spent nearly 5 million tons in 2013, according to the industrial group PetroChemicals Europe. And no wonder, for acrylic and the closely related acrylates are the building blocks for many kinds of plastics, adhesives, textiles, dyes, paints and papers. Tightened together in long chains, they can make all kinds of useful materials. Acrylate mixed with sodium hydroxide, for example, makes a superabsorbent material used in diapers. Add extra methyl groups (carbon plus three hydrogens) and acrylate makes plexiglass.
Current acrylic industrial processes 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's Materials Science Institute and colleagues at UConn and ExxonMobil, has designed a new way of making acrylic at low temperatures. Their technique can be fine-tuned to avoid unwanted chemicals.
"Researchers from ExxonMobil Research & Engineering, working with Professor Suib's UConn Group, have explored new technologies that can lower energy intensity, step up, improve energy efficiency, and reduce carbon footprint in the acrylic production process," said Chemist Partha Nandi 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 the reactions. Often they give a surface to the molecules to sit on while they react with each other and help them meet in the right configurations to do the deed. In this case, the pores fill that role. The pores are 20 to 500 years wide, large enough for fairly large molecules to fit inside. The manganese atoms in the material can trade their electrons with nearby oxygen, making it easier for the right chemical reactions to occur. Depending on the starting materials, the catalyst can facilitate all kinds of acrylic and acrylates, with very little waste, says Suib.
"We hope this can be scaled up," he says. "We will maximize yield, minimize temperature and make an even more active catalyst," which will help the reaction faster. The group also found that adding a little lithium helped make it too fast. They are currently studying the exact role of lithium and experimenting with ways to improve the manganese and oxygen catalysts.