Vol. 19, No. 14

Dec. 9, 1999

DuPont donates 'green'
manufacturing method

Chemical manufacturers could use two-thirds less energy on many processes, while saving up to 10 percent in starting-material costs and capital investment for a host of products, thanks to DuPont Co. technology donated to UD. By reducing unwanted byproducts, the environmentally friendly technique "also could potentially save up to a million dollars in annual disposal costs for certain processes," said T.W. Fraser Russell, chemical engineering. "DuPont's gift of technology should benefit the environment and chemical manufacturers, as well as Delaware students, who will explore strategies for adding value to the patent," University President David P. Roselle said. Already successful in pilot-scale demonstrations, the technology is nearly ready to be licensed to industrial firms, said Russell, the University's A.P. Colburn Professor of Chemical Engineering. DuPont Fellow Vincent G. Witterholt, one of the company's three Distinguished Scientists, said the "green" manufacturing technique will be "very useful for making a wide variety of chemical intermediates, which are then used to create specialty products, including pharmaceuticals, agrichemicals and plastics." Why would DuPont give up valuable technology? Every year, DuPont researchers generate many more promising ideas than they could ever hope to commercialize, and maintaining "idle patents" can be costly, explained Thomas Woods, special projects manager within the company's Crop Protection Products business. Still, the green approach to making chemical intermediates "is absolutely viable and useful," Woods said, adding that "UD is well-positioned to fully exploit the technology," developed for use in a material DuPont currently doesn't sell. Costel D. Denson, vice provost for research at UD, said corporate gifts of patented technology are on the rise. "It's definitely a trend in higher education," Denson said. "Leading corporations like DuPont own so many patents, some of those disclosures inevitably will lie on a shelf, particularly if the company reinvents itself to enhance competitiveness. The legal upkeep on patents is very expensive, so smart managers look for ways to share that knowledge. At the same time, corporations are increasingly interested in collaborative research." Before they can produce a broad range of plastic materials, fungicides, certain medicines or the food preservative, benzoic acid, chemical makers must first generate the right raw materials and intermediates. Producing the common plasticizer, butyl benzyl phthalate, for example, requires a chemical intermediate known as benzyl chloride. Herbicide production often involves similar intermediates and derivatives of fluoroalkyl aromatics. Two important types of intermediates-hydrocarbons and silane compounds-"usually are produced today by bubbling chlorine through a hot, raw material," so that chlorine atoms latch onto other molecules, Russell said. The problem with this approach, Witterholt said, is that "you have to stop the reaction halfway through the process to avoid overchlorinating everything. It's a scatter-shot strategy, and you can easily wind up with four chlorine atoms where you wanted two." The result, he said, is a lower product yield and too many byproducts, which then must be distilled or otherwise separated from the product and distilled. By comparison, the DuPont/UD technology selectively chlorinates starting materials, offering greater control over the process. "You get very high yields of the desired product, up to 95 percent, compared to maybe 50 percent for the more traditional approach," Witterholt said. By harnessing light to trigger the chemical reaction, and then quickly separating the chlorinated product from the starting material, DuPont researchers increased efficiency, while reducing waste. In the new "photochlorination/reactive distillation" system, Russell explained, "Light induces a very fast reaction, and heavier, chlorinated molecules are separated in a distillation column, which prevents further chlorination. It's poetically simple!" Laboratory and pilot-scale experiments to date have been extensive, and will allow a commercial-scale design to be prepared for a wide variety of critical chemicals, Russell added. While UD faculty will spearhead commercialization efforts, senior undergraduate students are expected to learn from the DuPont technology in one of Russell's courses. "DuPont's generous gift clearly will reduce energy use and chemical waste in industry," Russell said. "It also will provide hands-on learning opportunities for the next generation of engineers."