Design and optimization of novel heterogeneous catalysts by 3D printing

The increasing environmental consciousness of modern society challenges the chemical community to develop catalytic systems that enable chemical processes with a reduced environmental impact (E-factor). Transition metal-catalyzed reactions (TMCR) occupy a prominent position among modern synthetic methods in industrial and academic laboratories. The excellent selectivity and functional group compatibility of TMCR offer robust and mild synthetic alternatives for the synthesis of natural products, pharmaceuticals, agrochemicals or polymers. Nevertheless, leaching of the metal into the reaction medium is a critical problem that hampers the application of TMCR in the pharmaceutical industry. The strict safety guidelines of regulatory agencies limit the acceptable levels of most transition metals within drugs to the low ppb range. In this context, catalyst immobilization is an appealing strategy that, in addition to facilitating catalyst recovery and operation in a continuous-flow format, has proven to give higher catalytic performance, since the solid support usually imparts chemical, thermal, and mechanical stability to the catalytic species.



The emergence of 3D printing methods has impacted almost all areas of research and industry. This revolutionary technology stands out due to the key advantage of the fabrication of three-dimensional physical objects from a digital model by taking a virtual design from computer-aided design (CAD) software and reproducing it layer by layer until the physical definition of the layers gives the designed product. The 3D printing technique enables the fabrication of monoliths with different cross sections, pore sizes, and wall thicknesses, thus maximizing the catalytic surface. More importantly, the fabrication parameters can be tuned to obtain parts with excellent mechanical properties. In the context of catalysis, 3D printing offers plentiful unexplored avenues in the field of heterogeneous catalysts. In addition to the possibility of exquisite modulation of shape, size and metal loading of the catalytic system, 3D printing enables fine tuning of other critical parameters that influence both the macro- and microscopic aspects of catalysts.

The Sotelo laboratory, in collaboration with the Galician Ceramic Institute, pioneered the use of 3D printing concepts in the development of environmentally friendly heterogenous catalysts based on ceramic materials. These efforts provided the first 3D printed heterogeneous (copper) catalyst on an alumina support, new catalytic systems obtained by surface functionalization and metal (palladium or copper) heterogenization on a 3D printed silica support.

Three-Dimensional Printing in Catalysis: Combining 3D Heterogeneous Copper and Palladium Catalysts for Multicatalytic Multicomponent Reactions

Díaz-Marta, A.S. Tubío, C.R., Carbajales, C., Fernandez, C., Escalante, L., Sotelo, E., Guitián, F., Barrio, V. L., Gil, A., Coelho, A.

3D-Printing of a Heterogeneous Copper-Based Catalyst

Tubio, C. R., Azuaje, J., Escalante, L., Coelho, A., Sotelo, E. Gil, A.