3D printing of catalysts

Article by Neil Clark

CHEMICALLY active catalysts have been 3D printed in a single step, which researchers say could allow the rapid production of customised designs across several industries.

The process can print catalysts in any shape-- in this demonstration the Ames Laboratory logo (Credit: Ames)

While 3D printing has found applications in many areas, its use as a way to control chemical reactions, or catalysis, is relatively new. Current production of 3D catalysts typically involves various methods of depositing the chemically active agents onto pre-printed structures.

Now, a team from the US’ Ames Laboratory and Iowa State University has developed a method using commercial stereolithographic 3D printers, which combines catalyst structure and functional chemistry in one step.

The technique works by shining a laser through a bath of bifunctional resins that polymerise and harden layer-by-layer. Functionalities in resins include a polymerisable vinyl group, to assemble the 3D structures, and a secondary group to provide them with active sites – resulting in a final product with intrinsic catalytic properties.

“The monomers, or building blocks that we start with, are designed to be bifunctional. They react with light to harden into the three-dimensional structure, and still retain active sites for chemical reactions to occur,” said Sebastián Manzano, a researcher from Iowa State.

The catalysts demonstrated success in several reactions common to organic chemistry. In an ACS Catalysis paper, the researchers demonstrated that structures containing accessible carboxylic acid, amine, and copper carboxylate functionalities were catalytically active for the Mannich, aldol, and Huisgen cycloaddition reactions, respectively.

Catalysts can be built in one step by directly shining a laser through a bath of customized resins that polymerize and harden layer-by- layer (Credit: Ames)

The functional groups in the 3D-printed structures were also amenable to postprinting chemical modification, making multi-step reactions possible.

As proof of principle, chemically active cuvette adaptors were 3D printed and used to measure the kinetics of a heterogeneously catalysed Mannich reaction, and 3D-printed millifluidic devices with catalytically active copper carboxylate complexes were also used to promote azide–alkyne cycloaddition under flow conditions.

“We can control the shape of the structure itself, what we call the macroscale features; and the design of the catalyst, the nanoscale features, at the same time”, said Igor Slowing from Ames. “This opens up many possibilities to rapidly produce structures custom designed to perform a variety of chemical conversions.”

ACS Catalysis: http://doi.org/cftj

Article by Neil Clark

Staff Reporter, The Chemical Engineer

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