Digital Chemistry as a robust tool for the design of heterogeneous catalysts for direct amination reactions´┐╝

Amines are important building blocks in the chemical industry, serving as intermediates in the manufacture of agrochemicals, surfactants, polymers, pharmaceuticals, solvents and dyes. Among the technologies for amine synthesis, the direct amination of alcohols with ammonia stands out as an atom-efficient and environmentally benign route, since water is generated as the sole by-product. So far, chemical intuition and serendipity have been the drivers of advancements in catalyst discovery for amination reactions. Nevertheless, trial-and-error is inherently limited by time and cost constraints. In this view, it is urgent to develop heterogeneous catalysts where knowledge can drive fast catalyst discovery in an automated/digital fashion.

In this work, we combined first-principles calculations, scaling relations, kinetic simulations and catalysis experiments to unveil the key factors governing the activity and selectivity of metal catalysts for the model amination reaction of 1-octanol with NH3. We show that the loss of selectivity towards primary amines is linked to a surface-mediated C-N bond coupling between two N-containing intermediates: CH3NH and CH2NH. The barrier for this step is low enough to compete with the main surface hydrogenation reactions and can be used as a descriptor for selectivity. The combination of activity and selectivity maps using the C and O adsorption energies as descriptors was used to fast-screen 348 dilute bimetallic catalysts. Among the best theoretical candidates, Co98.5Ag1.5 and Co98.5Ru1.5 (5 wt% Co) were identified as the most promising catalysts and their improved selectivity was confirmed by catalytic experiments using an automated 3-bed flow reactor.

Next, we optimized the preparation of CoRu and CoAg catalysts to access 1-octylamine from the reaction of 1-octanol with NH3. The impregnation protocol was found to be critical with the best results being obtained for sequentially impregnated Ag-Co and co-impregnated Co(Ru) catalysts. Further optimization of the Ag and Ru metal loading led to two formulations affording a comparable activity to that of an Al2O3-supported catalyst containing 2.4 times more Co. At optimized conditions, the best formulation (5wt.%Co, 3 atom%Ag) afforded 90% conversion and 78% yield to 1-octylamine in the gas-phase amination reaction of 1-octanol with NH3 at 200 oC using 21 equiv. of NH3 compared to 1-octanol.

The results presented in this study outline the power of computational tools combined with machine learning algorithms for the rational design of amination catalysis. The methodology presented in this study is transversal and can be applied to other catalysts for industrially relevant reactions, and constitutes a path towards the dream to accomplish the in silico design of heterogeneous catalysts.

Biography

Prof Marc Pera-Titus is Chair of Sustainable Catalytic Chemistry and Director of International (DoI) at the School of Chemistry in Cardiff University (Wales, UK). Marc received a double MSc degree in Chemical Engineering (2001) and Physical Chemistry (2002), and a PhD (2006) from University of Barcelona (Catalonia, Spain). In 2007, he joined Ircelyon/CNRS (France) as postdoc and was further appointed CNRS fellow in 2008. From 2011-2020, Marc was project leader, expert and deputy director at the E2P2L CNRS-Solvay joint laboratory in Shanghai (China), merging industrial and academic research. Marc is author of 136 papers and inventor of 19 patents in the fields of membranes, adsorption, catalysis and process eco-design. Marc has received numerous awards, including the Rh├┤ne-Alpes Foundation Award (2007), the Elsevier Award for highly cited author in Catalysis (2009), the Silver and Gold Medals from the Chinese Academy of Inventions (2016, 2017), the DivCat award from the French Society of Chemistry (2017), a ERC consolidator grant (2018), and personal grants from ANR (2017) and EPSRC (2021). Since 2021, he is fellow of the Royal Society of Chemistry.Prof Marc Pera-Titus is Chair of Sustainable Catalytic Chemistry and Director of International (DoI) at the School of Chemistry in Cardiff University (Wales, UK). Marc received a double MSc degree in Chemical Engineering (2001) and Physical Chemistry (2002), and a PhD (2006) from University of Barcelona (Catalonia, Spain). In 2007, he joined Ircelyon/CNRS (France) as postdoc and was further appointed CNRS fellow in 2008. From 2011-2020, Marc was project leader, expert and deputy director at the E2P2L CNRS-Solvay joint laboratory in Shanghai (China), merging industrial and academic research. Marc is author of 136 papers and inventor of 19 patents in the fields of membranes, adsorption, catalysis and process eco-design. Marc has received numerous awards, including the Rh├┤ne-Alpes Foundation Award (2007), the Elsevier Award for highly cited author in Catalysis (2009), the Silver and Gold Medals from the Chinese Academy of Inventions (2016, 2017), the DivCat award from the French Society of Chemistry (2017), a ERC consolidator grant (2018), and personal grants from ANR (2017) and EPSRC (2021). Since 2021, he is fellow of the Royal Society of Chemistry.

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