NCSU researchers advance butadiene production

RALEIGH, N.C.—Researchers at North Carolina State University have developed a new catalyst that improves the efficiency of converting butane, a component of natural gas, into butadiene, a building block in synthetic rubber and a variety of plastics.

The new lithium bromide catalyst process will address the existing "tricky" techniques that produce either unwanted by-products or convert only a small fraction of the butane into butadiene, the university said in a July 27 statement.

"This (existing technology) is an expensive process in terms of both energy and money," said Fanxing Li, corresponding author of the work and Alcoa professor of chemical and biomolecular engineering at North Carolina State University.

"Because after every pass through the chemical reactor, you have to separate the butadiene and by-products from the butane—which takes a lot of energy—and run the butane through the reactor again."

As a result, according to Li, there are very few plants devoted to producing butadiene.

Instead, much of the butadiene used in manufacturing comes from plants where butadiene is collected as a by-product of other reactions.

"That's a problem, because the demand for butadiene far outstrips the available supply," Li said.

For the new process, the team investigated developing a more efficient way of converting butane into butadiene, making butadiene production facilities more commercially viable.

Specifically, the researchers engineered a lithium bromide catalyst that converts more butane into butadiene with each pass through the reactor, compared to previous catalysts. The work was done using an oxidative dehydrogenation reaction.

"We were able to convert up to 42.5 percent of the butane into butadiene in a single pass," Li said.

This compares against the previous best performance the team could find, which stood around 30 percent.

"This is a big first step, but we view it as a proof of concept—we think we can still do a lot more to improve the selectivity of this process," Li said.

The catalyst itself is a lithium bromide shell surrounding a core of lanthanum strontium ferrite.

The reaction requires a modular reactor, and conversion takes place at between 450 and 500 degrees Celsius (842 and 932 degrees Fahrenheit).

Li and his team are "open to partnerships" to further explore the potential of the work.