Modified Catalyst Simplifies Manufacture Of Myriad Goods

October 01, 1997

By tweaking the structure of a class of increasingly popular chemical catalysts known as metallocenes, chemists at the University of Rochester have uncovered a much simpler way to make the material that forms the basis of a wide range of consumer goods, including soaps, detergents, oils, and plastics. If the procedure can be scaled up for industrial use -- a question the research team is now investigating -- goods made out of billions of tons of plastics and petroleum-based products should become less expensive and safer to produce. The findings are discussed in the October 1 issue of the Journal of the American Chemical Society.

"This is a spectacularly interesting finding," says Rick Kemp, a senior research scientist at the Union Carbide Corporation and an expert in the class of materials known as alpha-olefins, which form the chemical backbone of many consumer products. "The new catalyst appears to yield products that are virtually 100 percent pure, a trait that's increasingly desirable in industry."

Scientists making alpha-olefins typically need temperatures of 400 to 500 degrees Fahrenheit and pressures of 100 to 200 atmospheres. That's because they use aluminum or nickel catalysts, which require extreme pressures and temperatures to work.

"It's costly to attain these conditions and build the reactors needed to make alpha-olefins with aluminum or nickel catalysts," says Guillermo Bazan, associate professor of chemistry and primary author of the JACS article.

Bazan's modified metallocene catalyst, bis(ethoxyboratabenzene) zirconium dichloride (BEZD), is capable of churning out alpha-olefins at only one atmosphere of pressure and temperatures just slightly above room temperature. BEZD strings ethylene molecules end-to-end to form alpha-olefins just as quickly as traditional aluminum and nickel catalysts, Bazan says. It also gives scientists precise control over just how long the chains grow. Under varying pressure, BEZD can produce carbon chains ranging from ethylene dimers, with just four carbons atoms, all the way up to full-fledged polymers containing many thousands.

"There are a million and one uses for alpha-olefins," Kemp says. "In addition to serving as precursors for detergents, synthetic lubricants, and octane enhancers, they're used to produce a significant fraction of the 150 billion pounds of polyethylene and polypropylene produced each year -- plastics found in products ranging from ice cube trays to textiles to bottle caps to trash bags."

To make the new catalyst, Bazan put a new spin on metallocenes, a class of catalysts currently taking the world of plastics by storm. Scientists have known for more than 40 years that these materials have potent catalytic properties, but it's only recently that the plastics industry has begun to take advantage of them to create polymers.

The catalyst molecule Bazan created bears a striking structural and electronic resemblance to metallocenes, which typically include two five-carbon rings bracketing a single atom of the transition metal zirconium. Bazan's molecule features six- membered rings containing five carbons and an added boron atom to regulate zirconium's reactivity. But the molecules that grow in the presence of the two catalysts are dramatically different. While traditional metallocenes yield long polymers of ethylene, BEZD leads to alpha-olefins, which are much shorter, versatile, and easily modified organic chains. While research by Shell in the Netherlands has shown limited success making alpha-olefins using metallocene-like catalysts, Kemp believes Bazan's approach is more sophisticated and leads to far better products.

By working with chemical companies, Bazan hopes to determine within the next year whether BEZD is an industrially feasible means of producing alpha-olefins.

Graduate students Jonathan Rogers and Caroline Sperry joined Bazan in the research, which was funded by the Alfred Sloan Foundation and the Henry and Camille Dreyfus Foundation.

University of Rochester

Related Plastics Articles from Brightsurf:

Bioplastics no safer than other plastics
Bioplastics contain substances that are as toxic as those in ordinary plastics.

A first-of-its-kind catalyst mimics natural processes to break down plastics
A team of scientists led by the U.S. Department of Energy's Ames Laboratory has developed a first-of-its-kind catalyst that is able to process polyolefin plastics, types of polymers widely used in things like plastic grocery bags, milk jugs, shampoo bottles, toys, and food containers.

Plastics, waste and recycling: It's not just a packaging problem
Discussions of the growing plastic waste problem often focus on reducing the volume of single-use plastic packaging items such as bags, bottles, tubs and films.

'Critical' questions over disease risks from ocean plastics
Key knowledge gaps exist in our understanding of how ocean microplastics transport bacteria and viruses -- and whether this affects the health of humans and animals, researchers say.

Plastics, pathogens and baby formula: What's in your shellfish?
The first landmark study using next-generation technology to comprehensively examine contaminants in oysters in Myanmar reveals alarming findings: the widespread presence of human bacterial pathogens and human-derived microdebris materials, including plastics, kerosene, paint, talc and milk supplement powders.

Chemists make tough plastics recyclable
MIT chemists have developed a way to modify thermoset plastics with a chemical linker that makes it much easier to recycle them, but still allows them to retain their mechanical strength.

The many lifetimes of plastics
Many of us have seen informational posters at parks or aquariums specifying how long plastics bags, bottles, and other products last in the environment.

Recycling plastics together, simple and fast
Scientists successfully blended different types of plastics to be recycled together, providing a solution to the environmental problem of plastic waste and adding economic value to plastic materials.

Water replaces toxins: Green production of plastics
A new way to synthesize polymers, called hydrothermal synthesis, can be used to produce important high-performance materials in a way which is much better for the environment.

Untwisting plastics for charging internet-of-things devices
Scientists are unraveling the properties of electricity-conducting plastics so they can be used in future energy-harvesting devices.

Read More: Plastics News and Plastics Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to