Cooperative Catalysis Between Metal Single Atoms and Nanoparticles – COMET
Cooperative Catalysis Between Metal Single Atoms and Nanoparticles
Single metal atoms can be present in many supported catalysts (including commercial ones) in combination with metal particles, and have certainly played a role in many catalytic processes, but they have rarely been recognized as active sites.<br />The project aims to develop a new generation of catalysts, combining in a controlled manner isolated atoms and metallic particles, in order to achieve cooperative catalysis.
Study of cooperative catalysis between isolated metal atoms and metal nanoparticles
Supported metal catalysts dominate the production technology of chemicals, fuels and polymers, and help protect the environment. Since the active phases are often composed of noble metals, expensive and for the most part identified as critical elements, a logical step is to optimize their dispersion on the support. The supported single atoms allow the maximum dispersion of the metal to be achieved. Aided by recent advances in synthetic methodologies, characterization techniques and modeling, catalysis on single atoms has become the most active new frontier of heterogeneous catalysis. A supported metal single atom catalyst (SAC) contains only single atoms integrated on a supported. The absence of ensemble effects, and the presence of strong electronic effects of the support, which modify the electronic structure of a metal atom in the SAC, significantly affect the adsorption, and induce a different reactivity compared to metal nanoparticles (NPs). Therefore, SACs exhibit distinct performance from metallic NPs for a wide variety of chemical reactions, and industrial applications have already been reported. The fact that this type of catalyst is already installed on industrial units reflects their potential stability. Of course, depending on the catalytic reaction, these marked differences in reactivity with NPs can be positive or negative, and as with any catalyzed reaction, a reaction/catalyst match must be found. Single atom can coexist with NPs in many catalysts, including, as recently observed, in commercial catalysts. They probably play an important role in many catalytic processes, but they have rarely been recognized as active sites; either because it was not possible to detect them, or because they were supposed to be inactive.<br />The concept of SAC-NP cooperative catalysis is new. However, it should be noted that the deposition of isolated atoms, which are active for the activation of hydrogen on non-active or not very active metallic NPs has already been carried out in Fischer-Tropsch synthesis several years ago. A few years later, the concept of a single atom alloy was introduced, in which a single atom isolated on a metal NP can drastically influence the catalytic properties of the less reactive metal of the NP. However, it should be noted that this approach is limited to very low metal loads for SACs, as they are localized only on metal NPs, and not on the support.<br />In this context, the COMET project aims to develop a new generation of supported catalysts combining both SAC metal and NP in a controlled manner, in order to achieve cooperative catalysis for industrially relevant reactions in continuous flow.
The COMET project aims to develop a new generation of supported catalysts combining both isolated metallic atoms (SA) and metallic nanoparticles (NP) in a controlled manner, in order to achieve cooperative catalysis for industrially relevant reactions in continuous flow. In SA-NP cooperative catalysis, SAs and NPs facilitate reaction pathways that would be less favorable with a single type of site (SA or atoms on NPs). For this, experimental studies (to validate the concept and quantify the effects) and theoretical calculations (to understand the phenomenon) will be undertaken. Within the framework of the COMET project, with different active metals (Ni, Co, Pt and Ru), and three stimulating reactions: the selective hydrogenation of a, ß-unsaturated aldehydes, Fischer-Tropsch synthesis (FTS) and coupling dehydrogenating. For each of the three reactions studied, the best catalytic systems will be integrated into porous metal foams allowing very low pressure drops, and improved mass and heat transfers, for efficient continuous flow operation. Finally, DFT studies will support the experimental work to allow a rational development of these new catalytic systems, and to understand the cooperativity between SAs and NPs.
Different catalysts were prepared by a method that allows preparing both single atoms (SAs) and SA/nanoparticles (NPs) mixtures For each metal, we prepared catalysts with only SAs, only NPs, and different SA/NP ratio. A large variety of techniques (TEM, STEM-HAADF, EDX, HREM, N2 adsorption, chemisorption, XPS, EXAFS and XRD) were used for the characterization of these catalysts. The prepared catalysts were investigated for various reactions including the selective hydrogenation of cinnamaldehyde, 4-nitrophenol, acetophenone, 4-phenyl-2-butanone and R-(-)-carvone. The best compromise between SA/NP ratio, H-spillover and support activity was evaluated for each catalysts. We also aimed at performing CO2-FTS by combining SAs to perform RWGSR and NPs to perform the FTS. To transpose the selective hydrogenation to to flow process, a continuous gas-liquid system (tubular reactor with a catalytic internal) was designed from the kinetic results obtained in the stirred tank reactor. Solid metal foams on which the catalysts of interest are deposited limit the system’s pressure losses and ensure thermal homogeneity within the reactor.
We also performed DFT calculations, which have focused on three main goals: (i) computational design of a supported metal catalyst that includes both NPs and SAs; (ii) H-spillover process on carbon-based materials; and (iii) reaction mechanism for the catalytic hydrogenation of molecules of interest.
Poursuite du projet et recherche de partenaires industriels
1. Cooperativity in supported metal single atom catalysis, P. Serp, Nanoscale, 2021, 13, 5985-6004.
2. Stabilization of metal single atoms on carbon and TiO2 supports for CO2 hydrogenation: the importance of regulating charge transfer, C. Rivera-Cárcamo, C. Scarfiello, O. Ersen, C. Le Berre, P. Serp, Adv. Mater. Interf., 2021, 8, 2001777.
3. Control of the single atoms/nanoparticles ratio in Pd/C catalysts to optimize the cooperative hydrogenation of alkenes, C. Rivera-Cárcamo, I. C. Gerber, I. del Rosal, B. Guicheret, R. Castro Contreras, L. Vanoye, A. Favre-Réguillon, B. F. Machado, J. Audevard, C. de Bellefon, R. Philippe, P. Serp, Catal. Sci. Technol., 2021, 11, 984-999.
4. Procédé de préparation d’atomes métalliques isolés ou d’un mélange d’atomes métalliques isolés et de nanoparticules métalliques sur matériau carboné, P. Serp, C. Rivera Carcamo, R. Philippe, B. Guicheret, FR3100723A1, 2021-03-19, Ecole Superieure De Chimie Physique Electronique De Lyon Cpe Lyon Centre National de la Recherche Scientifique CNRS Universite Claude Bernard Lyon 1 UCBL Institut National Polytechnique de Toulouse INPT
In recent years, single-atom catalysis has become a major research focus in heterogeneous catalysis. In these systems, the absence of ensemble effect and the existence of strong electronic effects of the support induce a reactivity very different from that of the metal particles.
Single-atom catalysts can be present in many supported catalysts (including commercial ones) in combination with metal nanoparticles, and have certainly played an important role in many catalytic processes, but they have rarely been recognized as active sites.
In this context, the COMET project aims at developing a new generation of supported catalysts, combining in a controlled manner isolated atoms and metal particles, in order to achieve a cooperative catalysis for continuous flow reactions. In this cooperative catalysis, isolated atoms and particles participate in the facilitation of reactions that would be less favorable on a single type of site. Preliminary results obtained by COMET project partners strongly support this innovative approach.
Monsieur Philippe SERP (Laboratoire de chimie de coordination)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
LPCNO-NCO LABORATOIRE DE PHYSIQUE ET CHIMIE DES NANO-OBJETS
LCC Laboratoire de chimie de coordination
LPCNO-MPC LABORATOIRE DE PHYSIQUE ET CHIMIE DES NANO-OBJETS
LGPC - CNRS LABORATOIRE DE GENIE DES PROCEDES CATALYTIQUES
RAPSODEE CENTRE DE RECHERCHE D'ALBI EN GENIE DES PROCEDES DES SOLIDES DIVISES, DE L'ENERGIE ET DE L'ENVIRONNEMENT
Help of the ANR 552,108 euros
Beginning and duration of the scientific project: October 2019 - 42 Months