Sustainability Sustains Its Appeal

Chemical companies continue to foster a switch to green technology.

By Seán Ottewell, Editor at Large

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A recent ranking of the 500 greenest companies in America by Newsweek ( put Eastman Chemical Co. at 95, making the Kingsport, Tenn., firm one of the chemical companies cited highest.

"Unlike many of its peers, [Eastman Chemical Co.] has largely avoided environmental controversies. Has also done an excellent job reporting on emissions and waste and has set concrete targets and goals to reduce air, greenhouse gases, and hazardous waste emission levels," noted the judges in their citation.

"This recognition is further reinforcement of the sound practices and systems we have in place throughout the company to ensure a sustainable future for our employees, our communities and our environment," noted Theresa Lee, Eastman's senior vice president with responsibility for environmental, health, safety and security programs.

One of the reasons behind Eastman's success is its breakthrough green biocatalytic process that already has won a 2009 Presidential Green Chemistry Challenge Award.

The new process uses enzymes and closely controlled conditions to make esters, eliminating the high temperature and strong acids traditionally required.

The cosmetic and personal-care industry in North America annually consumes an estimated 50,000 tons of esters for a variety of uses including emollients, emulsifiers and specialty performance ingredients. Eastman targeted its first biocatalytic venture here because the sector tends not to follow the cyclical nature of the chemicals market and also was growing very quickly when the project started three years ago.

Commenting on driving forces behind the new process, Eastman research associate Stephanie Clendennen said, "Until recently we had a fairly stable, low-cost petrochemical supply and less emphasis on sustainability issues. This has changed so much in the last three years. Now there is a wonderful emphasis on sustainability. Along with that, technological advances such as lower-cost enzyme catalysts and membrane-based separation technologies are maturing and can be applied to more green processes."

"Generally it's all about cost. We don't deal directly with consumers much, but our customers do. And that will be where the big push forward comes from," added Eastman technology fellow Neil Boaz.

Eastman now has synthesized a variety of esters using enzymes at mild temperatures. Esterifications are driven to high conversion by removing co-product, usually water from esterification of an acid or a lower alcohol from transesterification of an ester. Filtration easily removes the immobilized enzyme, e.g., lipase. Specificity of the enzymatic conversions and relatively low reaction temperatures minimize formation of byproducts (some of which could affect color and odor), increase yield and cut energy consumption. The process reportedly can save more than 10 liters of organic solvent per kilogram of product.

"We performed an internal evaluation using published data and methods. This estimates that when this process is compared with a traditional synthetic route that uses high-temperature distillation/separation post-reaction steps, it saves up to 86% of energy usage and the same percentage of greenhouse gas emissions," noted Boaz.

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