New catalyst boosts yield on biomass to plastic process to 97%
A process to convert biomass feedstocks into p-xylene, a key ingredient in plastics, has been developed by a team of researchers from four US universities. The researchers used a new zeolite catalyst to gain a 97% yield from the process, whereas previous efforts to produce p-xylene in this way reportedly achieved no more than 75% yield. P-xylene is a chemical used to make polyethylene terephthalate (PET), a polymer used in products such as bottles, food packaging, auto parts and clothing.

A team from the University of Massachusetts Amherst, the University of Minnesota, the University of Pennsylvania and the University of Delaware has developed a new chemical process to make p-xylene, an important ingredient of common plastics. The new method has a 97% yield and uses biomass as the feedstock. P-xylene is currently produced from petroleum. The research is featured in the current issue of the journal ChemCatChem .

Xylene chemicals are used to produce a plastic called PET (polyethylene terephthalate), which is currently used in many products including soda bottles, food packaging, synthetic fibers for clothing and automotive parts. Global market forecasts estimate that the market for plastic products using this chemical will grow by about 5% annually.

The key to the new process, which builds on previous work by the research team, is a new zeolite catalyst that directs the liquid chemical reaction to produce p-xylene and discourages the production of other byproducts. Previous efforts to make p-xylene in this manner have not achieved a yield higher than 75%. The new zeolite was synthesized to contain phosphorous which helps create a much more selective chemical reaction that almost exclusively yields p-xylene.

The phosphorous containing zeolite catalysts exhibit high surface area and well dispersed phosphorous active sites. Different from conventional acid catalysts, the phosphorous containing zeolite catalysts is highly selective for p-xylene production. The selectivity is unique and has not been observed in the past. It can be easily used for many other important catalytic reactions. —Professor Wei Fan, U Mass Amherst

The research team is part of the Catalysis Center for Energy Innovation that seeks to find breakthrough technologies for producing biofuels and chemicals from lignocellulosic biomass. The center is funded by the US Department of Energy as part of the Energy Frontiers Research Center (EFRC) program, which involves more than 20 faculty members with complementary skills to collaborate on solving the world’s most pressing energy challenges.

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