New process makes butadiene from biomass

ENGINEERS in the US have developed a highly selective process to convert sugars derived from biomass, like wood and grasses, into butadiene, a vital component of synthetic rubbers.

Butadiene is a hugely important commodity chemical. It is one of the main components of styrene-butadiene rubber (SBR), used to make vehicle tyres; of nitrile butadiene rubber (NBR), used to make hoses, seals and nitrile gloves; and of acrylonitrile-butadiene-styrene (ABS), a hard plastic used in games consoles, medical devices, and car parts, amongst other things. It is generally made from petroleum, so many researchers are seeking a sustainable, non-fossil production process. The researchers at the Universities of Delaware, Minnesota and Massachusetts believe their new, renewable process, which exhibits over 95% selectivity for butadiene, could transform butadiene production.

The three-step process makes use of both novel chemistry and a new catalyst. The first step begins with five- or six-carbon sugars, such as glucose or xylose, which can be obtained from biomass. The team first convert this to furfural, before converting the furfural to tetrahydrofuran (THF).

Paul Dauenhauer, Minnesota chemical engineering associate professor, and one of the researchers, told The Chemical Engineer that the real breakthrough came in the third step (dehydra-decyclization) to convert THF to butadiene. The team developed a new type of catalyst, all-silica phosphorous zeolites, which consist of phosphorus-based catalysts supported by silica and zeolites.

“The new reaction combines two chemistries into a single reaction – dehydration and ring-opening. The new catalyst dehydrates more selectively than other solid acids. When these two are put together, it leads to unprecedented selectivity to butadiene,” said Dauenhauer

This high selectivity means that the process is also very economic.

“Each of the steps between xylose and butadiene is highly selective (>90%). Moreover, the major loss in economic value in any chemical process is low selectivity. Therefore, this new technology offers economic benefits beyond existing renewable rubber and plastic processes due to its unprecedented selectivity to butadiene (95–98%),” Dauenhauer said.

ACS Sustainable Chemistry and Engineering doi.org/b6jb