Washington [US]May 29 (ANI): According to research conducted by the Institute for Cooperative Upcycling of Plastics (iCOUP), the created catalysts for breaking down plastics continue to drive plastic upcycling processes.
The findings of the study have been published in the Journal of the American Chemical Society.
In 2020, a team of researchers developed the first processive inorganic catalyst to deconstruct polyolefin plastics into molecules that can be used to make more valuable products. Now the team has developed and validated a strategy to accelerate transformation without sacrificing desired products.
The catalytic converter was originally designed by Wenyu Huang. It consists of platinum particles supported on a solid silica core and surrounded by a silica shell with uniform pores that provide access to catalytic sites. The total amount of platinum required is quite small, which is important due to the high cost and limited supply of platinum. During deconstruction experiments, the long polymer chains are threaded into the pores and come into contact with the catalytic sites, after which the chains are broken into smaller pieces that are no longer plastic (see image for more details).
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Aaron Sadow, a scientist at Ames Lab and director of the Institute for Cooperative Upcycling of Plastics (iCOUP), explained that the team created three variants of the catalyst. Each variant had identically sized cores and porous shells, but different platinum particle diameters, from 1.7 to 2.9 to 5.0 nm.
The team hypothesized that the differences in platinum particle size would affect the length of the product chains, so large platinum particles would make longer chains and small ones would make shorter chains. However, the group found that the lengths of the product chains were the same for all three catalysts.
“In the literature, the selectivity for carbon-carbon bond cleavage reactions usually varies with the size of the platinum nanoparticles. By placing platinum at the bottom of the pores, we saw something very unique,” Sadow said.
Instead, the rate at which the chains were broken into smaller molecules was different for the three catalysts. The larger platinum particles reacted more slowly with the long polymer chain, while the smaller ones reacted faster. This increased velocity may be due to the higher percentage of edge and corner platinum sites on the surfaces of the smaller nanoparticles. These sites are more active in cleaving the polymer chain than the platinum contained in the planes of the particles.
According to Sadow, the results are important because they show that the activity can be adjusted independently of the selectivity in these reactions. “Now we are confident that we can make a more active catalyst that would eat the polymer even faster, while using catalyst structural parameters to set specific product chain lengths,” he said.
Huang explained that this type of reactivity of larger molecules in porous catalysts is generally not widely studied. So the research is important for understanding basic science and how it performs for plastics upcycling.
“We really need to understand the system better because we’re still learning new things every day. We’re exploring other parameters that we can fine-tune to further increase production speed and shift product distribution,” said Huang. “So there are a lot of new things on our list waiting to be discovered.” (ANI)
(This is an unedited and auto-generated story from the syndicated news feed, the Laatstely staff may not have changed or edited the content)
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