Perkin Medal winner reflects on her role in the science of keeping cool

Barbara Minor, a corporate fellow at Chemours, works in a world of cool chemicals. She designs and tests molecules that keep food from spoiling and people from overheating in hot weather.

She was part of a team that developed the first refrigerants with low global-warming and no ozone-depleting potential. She also developed several refrigerants that extended the technology to supermarket refrigeration systems, refrigerated trucks, and large-building chillers.

In recognition of these achievements, Minor will receive the Perkin Medal, which acknowledges outstanding work in applied chemistry, at a dinner in her honor on Sept. 25 at the Bellevue Hotel in Philadelphia. Sponsored by the America Group of London-based Society of Chemical Industry, the award first went in 1906 to William Henry Perkin, who launched a textile dye revolution with the discovery of mauve in 1856.

This year’s Perkin Medal recipient participated in an upheaval of a different sort, brought about by the Montreal Protocol on Substances That Deplete the Ozone Layer. When the protocol entered into force in 1989, it mandated the phaseout of halogenated hydrocarbons that deplete Earth’s protective upper atmospheric ozone layer.

That year, Minor joined a new research group at Chemours’s predecessor, DuPont, that worked to find alternatives to ozone-depleting refrigerants. While she had earlier worked in a variety of roles, including as a process engineer at DuPont’s Chambers Works site in New Jersey and as an engineering supervisor in the firm’s fluorochemical business, the new job brought her to a refrigerant research lab. “I’ve been there ever since,” she says.

During Minor’s first few years in the lab, she and her colleagues focused on developing hydrochlorofluorocarbon and hydrofluorocarbon refrigerants that had significantly lower impact on upper atmospheric ozone levels. One of the results was the automotive refrigerant hydrofluorocarbon-134a (HFC-134a).

However, scientists soon realized that some of the agents with low ozone-depleting potential, including HFC-134a, were also powerful global warming gases.

The DuPont researchers then adopted a new goal: refrigerants that combine no ozone-depleting and low global-warming potential. Beginning in 2004, Minor says, she and her group homed in on hydrofluoroolefins (HFOs) as the best candidate to achieve that goal. Another firm, Honeywell International, was pursuing a similar line of research.

“We were working independently of Honeywell on HFO refrigerants,” Minor recalls. Then in 2006, the European Union issued a ban on the use of HFC-134a. Beginning with the 2011 model year, new cars could not use HFC-134a, which has a global-warming potential (GWP) 1,300 times as great as that of carbon dioxide. Replacements would need to have a GWP rating of 150 or less.

To meet the deadline, DuPont and Honeywell scientists began to work together in 2007 to do all the work necessary to settle on and qualify a low-GWP replacement for HFC-134a for use in cars. “New chemicals take years to develop,” Minor says. In addition to making certain the chemical does what it needs to do, researchers had to run a battery of tests, including toxicological and flammability checks, she says.

The companies collaborated for about a year. “It made sense to share the work,” Minor says, so the two chemical makers could offer car manufacturers an alternative in time to qualify air-conditioning equipment that could work efficiently with a new refrigerant.

In the effort, Minor worked with Honeywell research leader Ian Shankland to find the right molecule. Shankland won the 2008 Perkin Medal for his role in developing environmentally friendly refrigerants. The two groups settled on HFO-1234yf, a molecule with a GWP less than that of carbon dioxide.

After identifying HFO-1234yf, “my role was to oversee safety and flammability testing,” Minor says. In addition, her group examined the basic properties of the molecule, such as its thermal stability and compatibility with materials used in air-conditioning equipment.

Minor and her group used gas chromatography/mass spectrometry (GC/MS) to analyze refrigerant samples for impurities that could compromise effectiveness. To test for stability, for instance, she might seal a refrigerant and associated lubricant in a glass tube and then heat the mixture. GC/MS analysis would reveal degradation products. “It all goes back to defining a problem and looking at it from a technical perspective,” she says.

Automakers ultimately adopted HFO-1234yf as a replacement for HFC-134a. European regulators soon pushed for climate-friendly refrigerants in other applications, such as freezers and ice makers.

Minor developed several blends, many based on HFO-1234yf, which could do the job. Blends she developed include Opteon XP40 for supermarket refrigeration systems and Opteon XP44 for refrigerated trucks and trailers.

Minor didn’t start out with a desire to be a chemical engineer. Growing up in northern New Jersey, she was more interested in biology. For one, her mother was a biology major and worked for the pharmaceutical firm Merck & Co. before leaving her job to raise a family. Also, her favorite teacher at Northern Highlands Regional High School in Allendale, N.J., was her biology teacher, Vince Herold.

“When I went to college, I started out as a biology major,” Minor says. There, many of the students in her biology classes aspired to become medical doctors, but she didn’t find that path appealing.

What did appeal were the courses her friends in engineering were taking because they were solving problems, she says. Minor also liked her organic chemistry class because of “the symmetry of the subject, the rules, and the concrete nature of the discipline.”

Also at that time, job prospects were good for college graduates with chemical engineering degrees, Minor says. Two weeks after graduating in 1981 from Bucknell University with a chemical engineering degree, she went to work for DuPont.

Minor’s years of experience at DuPont led to her 2014 appointment as a corporate fellow, the highest technical professional level in the firm. She remains a corporate fellow at Chemours, where her experience, technical proficiency, and leadership abilities help her guide younger colleagues.

She worries that many young chemical engineers may not get the support in developing their careers that she had. She got such help from Donald Bivens, a technology fellow at DuPont who retired in 2009. A refrigerants expert who developed many of the HFCs used in the 1990s, Bivens “was supportive and challenged me to work with customers. I owe a lot of my success to his mentorship,” she says.

Minor advises early-career chemical engineers to take charge of their careers, seek out mentors, and do the best job they can on their current assignments. “That’s the best way to get a new and more challenging assignment,” she says. If they’re lucky, it will be an assignment that could solve important global problems.