Converting plastic to lubricating oil

USA Today (Society for the Advancement of Education), April, 2006

Recycled plastic bottles could be used to lubricate car engines one day, relate researchers at Chevron Energy Technology Company, Richmond, Calif., and the University of Kentucky, Lexington, who converted waste plastic into lubricating oil in laboratory experiments. These polyethylene-derived oils could help improve fuel economy and reduce the frequency of oil changes.

"This technology potentially could have a significant environmental impact. It could make a difference in communities that want to do something positive about their waste plastic problem, especially if there is a refinery nearby that could do all of the processing steps," says Stephen J. Miller, senior consulting scientist and Chevron Fellow.

Americans use about 25,000,000 tons of plastic each year. However, only about 1,000,000 tons of it are recycled, reports the Environmental Protection Agency. The remainder ends up in landfills. Some researchers have tried to use recyclable plastic to produce fuels, but commercial interest in this application has been limited. Most of this plastic is polyethylene, which the researchers demonstrated can be broken down by heat into a wax that can be converted into a high-quality lubricating oil.

Of the plastic employed in the pilot study, about 60% was converted into a wax with the right molecular properties for further processing to make lubricating oil for uses such as motor oil or transmission fluid. These high-quality oils derived from wax can assist auto manufacturers in meeting mandated fuel economy specifications, Miller declares.

The process for converting wax to lubricating oil was put into commercial use by Chevron in the early 1990s with waxy petroleum-derived sources. In the future, superior lubricating oils will be produced with wax extracted from a catalytic process known as Fischer-Tropsch, which starts with natural gas. It will be used commercially overseas, primarily in the Middle East, where natural gas is less costly than in the U.S. However, the study suggests that using wax originating from recyclable plastic can produce lubricants that are of equal quality compared to those derived from Fischer-Tropsch wax.