Rubber, for many years could be considered as a bio-based product. However, this natural rubber couldn’t be sustainable enough for long as there was a limit to the range of properties available to it. After the Second World War, refinements were added to the process for creating synthetic rubber. Now the rubber-based products that we use every day from car tyres, to toys, flooring and even the soles on our shoes, are made from synthetic materials. However, this man-made substance is manufactured using butadiene, a molecule made from petroleum or natural gas; until now. A team of scientists from three US research universities at the University of Delaware believe they have a new discovery which could transform industries. They have invented a process to make butadiene from renewable sources like trees, grasses and corn.
"The past ten years have seen a shift toward an academic research focus on renewable chemicals and butadiene, in particular, due to its importance in commercial products."
Butadiene is the chief chemical component in a broad range of materials found throughout society. When this four-carbon molecule undergoes a chemical reaction to form long chains called polymers, styrene-butadiene rubber (SBR) is formed, which is used to make abrasive-resistant automobile tyres. When blended to make nitrile butadiene rubber (NBR), it becomes the key component in hoses, seals and the rubber gloves.
The Catalysis Centre for Energy Innovation (CCEI) based at the University of Delaware is an Energy Frontier Research Centre funded by the US Department of Energy. “Our team combined a catalyst we recently discovered with new and exciting chemistry to find the first high-yield, low-cost method of manufacturing butadiene," says CCEI Director Dionisios Vlachos, the Allan and Myra Ferguson Professor of Chemical and Biomolecular Engineering at UD and a co-author of the study. "This research could transform the multi-billion-dollar plastics and rubber industries."
The past ten years have seen a shift toward an academic research focus on renewable chemicals and butadiene, in particular, due to its importance in commercial products, Vlachos says. The invention of renewable rubber is part of CCEI's larger mission. Initiated in 2009, CCEI has focused on transformational catalytic technology to produce renewable chemicals and biofuels from natural biomass sources.
"Our team's success came from our philosophy that connects research in novel catalytic materials with a new approach to the chemistry," says Vlachos. "This is a great example where the research team was greater than the sum of its parts."
Using technology developed within CCEI, the team converted sugars to a ring compound called furfural. In the second step, the team further processed furfural to another ring compound called tetrahydrofuran (THF).
It was in the third step that the team found the breakthrough chemical manufacturing technology. Using a new catalyst called "phosphorous all-silica zeolite," developed within the centre, the team was able to convert THF to butadiene with high yield (greater than 95 percent). The team called this new, selective reaction "dehydra-decyclization" to represent its capability for simultaneously removing water and opening ring compounds at once.
"We discovered that phosphorus-based catalysts supported by silica and zeolites exhibit high selectivity for manufacturing chemicals like butadiene," says Professor Wei Fan of the University of Massachusetts Amherst. "When comparing their capability for controlling certain industrial chemistry uses with that of other catalysts, the phosphorous materials appear truly unique and nicely complement the set of catalysts we have been developing at CCEI."
"This newer technology significantly expands the slate of molecules we can make from lignocellulose," says Prof. Paul Dauenhauer of the University of Minnesota, who is co-director of CCEI and a co-author of the study.
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