Biomass-Based Butadiene Beckons

July 28, 2017
Novel catalyst promises low-cost high-yield synthesis

A three-step process starting from biomass-derived sugars and involving a new catalyst could lead to greener production of butadiene — a key component for manufacturing synthetic rubber and plastics, says a team from three universities that developed the technology.

The research group behind the process hails from the Catalysis Center for Energy Innovation (CCEI) based at the University of Delaware (UD), Newark, and includes members from the University of Minnesota (UM), Minneapolis; and the University of Massachusetts, Amherst.

“This newer technology significantly expands the slate of molecules we can make from lignocellulose,” notes Paul Dauenhauer of UM and co-director of CCEI.

The team first converted sugars to a furfural, which they then transformed into tetrahydrofuran (THF). In the third step, the team developed a new catalyst called “phosphorous all-silica zeolite” to convert THF to butadiene. The selective reaction, dubbed “dehydra-decyclization,” simultaneously removes water and produces yields greater than 95%.

An article in ACS Sustainable Chemistry and Engineering contains more detail.

The phosphorus all-silica zeolite catalyst can transform other materials as well: “We have successfully used this catalyst for the production of bio-paraxylene with very high yield and selectivity for the first time and are evaluating its effectiveness for the production of a number of high-value, next-generation bio-products… We found this catalyst is effective for renewable para-xylene, butadiene and isoprene production that are important chemicals for tires and polymers,” explains Basudeb Saha of UD, and CCEI associate director.

In addition, Saha notes the catalyst’s acidity and ability to avoid side reactions make it a very attractive alternative to existing acid catalysts.

In terms of robustness, the team has evaluated the reusability of the catalyst for bio-paraxylene production. Testing the material under aggressive conditions, over long times, and in repetitive trials will be needed to further evaluate robustness, adds Saha.

In addition, there is some susceptibility to poisoning, including from impurities from biomass feed, starting substrates, trace process-derived byproducts, etc., note the researchers.

The catalyst is easy to produce and inexpensive, making it ideal for scale up, says Saha. “The technologies mentioned have been patented. We are seeking licensing of these technologies to companies for scale up. In case of any scale-up issues, our experts will investigate and mitigate the challenge.”

It will take 5–10 years minimum for commercialization, with several scale-up steps between discovery and having an actual plant, he adds.

Future work will focus on studying the active sites, densities and how the catalyst behaves in different solvents and reactions. “Having a firm understanding will help us introduce this catalyst to other systems,” notes Saha.

The team also is performing process intensification (continuous flow reaction, cascade reaction, reactive extraction, alternate heating, rapid and selective heating) of several bio-based processes using this and other catalysts to improve process efficiency and economics with a downsized reactor requiring minimal capital expenditure.