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The surprising discovery by chemists of nanoconfined reactions may aid catalytic design



  The surprising discovery of chemists for nanoconfined reactions may aid catalytic design
Credit: Georgia

Chemistry researchers at Georgia State University have unlocked one of the mysteries of catalytic reactions on a microscopic scale, allowing the design of more efficient industrial processes.


Catalysts ̵

1; which accelerate chemical reactions in everything from digestion of food to combustion engines in vehicles – are essential for the transformation of raw materials into useful products in industry, including oil, plastics, paper, pharmaceuticals and brewing. Understanding reactions can help scientists develop better catalysts that are more energy efficient and environmentally sustainable.

Researchers have created a new imaging strategy that can track single molecules as they change through small pores in shells of silicon spheres and observe the dynamics of chemical reactions at catalytic centers in the core, producing the first quantitative measurements of how retention on the nanoscale really accelerates the catalytic reactions.

Understanding this surprising "nanofinancing effect" could help guide the precise design of more efficient, energy-saving, industrial catalysts.

"You want to make a specific product and have a choice of different porous materials that can do different things. Which one will give you the best conversion rate and the highest speed?" says Ning Fang, an associate professor of chemistry in the state of Georgia who published research findings in Nature Communications . "We now have a theory based on experimental evidence that we add to the simulations to better predict what might be the result of using certain catalysts."

The study of catalytic reactions has previously been limited to theoretical and computational models. A one-molecule imaging system developed by Georgia Post-Doctoral Research Fellow and published in by Nature Catalysis allows researchers to first see and measure reactions occurring in a small multilayer porous sphere created by a collaborative porous sphere from the University of Iowa, led by Professor Wenyu Huang and PhD student Yuhen Pei.

Reagent molecules must be oriented in a particular direction to fit through nanopores – openings that are approximately 100 times smaller than the width of the hair strand. The nanopores are comparable in diameter to the size of the reagent molecule, and when its tip reaches the active nucleus, it immediately triggers the first contact reaction step. However, the generated intermediate is captured by the nanopore while the reaction proceeds through three steps to form the molecule of the final product.

Contrary to conventional theory, this "nanoporous barrier" accelerates the reaction rather than slows it down based on the experimental measurement of the Fang activation energy Although molecular motion is limited by the presence of the porous shell, the process is actually magnified by the closed, open-ended study.

"Instinctively, one would expect diminishing activity when catalytic centers are protected by nanoporous shell reagent molecules," said Fang. "However, our experimental evidence tells a different story. And more surprisingly, catalytic activities are further enhanced for catalysts with longer and narrower structures than nanopores, until the benefits of nanoconfiguration are outweighed by limited molecular transport in the nanoporous shell. "

This finding can have major implications in the design of new catalysts. For example, the equivalent of more than 500 million barrels of gasoline is used annually to convert ethane and propane into alkenes, which are used to produce plastics, cleaning products and other products. Implementing more efficient large-scale catalysts can save a lot of energy in the process.


Chemists Track Molecules Down 'Nanoscale', Track Catalytic Nanofinancing Reactions


More information:
Bin Dong et al. Deciphering the Effects of Nanoconciliation on Molecular Orientation and Reaction Intermediate by Single Molecule Imaging, Nature Communications (2019). DOI: 10.1038 / s41467-019-12799-x

Bin Dong et al. Deciphering the Effects of Nanoconciliation on Molecular Orientation and Reaction Intermediate by Single Molecule Imaging, Nature Communications (2019). DOI: 10.1038 / s41467-019-12799-x

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Georgia State University
Reference :
The surprising discovery by chemists of nanoconfined reactions may aid catalytic design (2019, November 6)
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