Abstract:The lack of selectivity for the direct amination of alcohols with ammonia, a modern and clean route for the synthesis of primary amines, is an unsolved challenge. Here, we combine first-principles calculations, scaling relations, kinetic simulations and catalysis experiments to unveil the key factors governing the activity and selectivity of metal catalysts for this reaction. We show that the loss of selectivity towards primary amines is linked to a surface-mediated C-N bond coupling between two N-containing i… Show more
“…1d , we are able to perform an efficient screening of potential active catalysts for alcohol dehydrogenation. Following a similar strategy as in our recent work on alcohol amination 54 , we computed the C and O adsorption energies for 294 dilute alloys and evaluated their credentials for dehydrogenation (Supplementary Table 9 ). As shown in Supplementary Fig.…”
Acceptorless dehydrogenation into carbonyls and molecular hydrogen is an attractive strategy to valorize (biobased) alcohols. Using 2-octanol dehydrogenation as benchmark reaction in a continuous reactor, a library of metal-supported catalysts is tested to validate the predictive level of catalytic activity for combined DFT and micro-kinetic modeling. Based on a series of transition metals, scaling relations are determined as a function of two descriptors, i.e. the surface binding energies of atomic carbon and oxygen. Then, a volcano-shape relation based on both descriptors is derived, paving the way to further optimization of active catalysts. Evaluation of 294 diluted alloys but also a series of carbides and nitrides with the volcano map identified 12 promising candidates with potentially improved activity for alcohol dehydrogenation, which provides useful guidance for experimental catalyst design. Further screening identifies β-Mo2N and γ-Mo2N exposing mostly (001) and (100) facets as potential candidates for alcohol dehydrogenation.
“…1d , we are able to perform an efficient screening of potential active catalysts for alcohol dehydrogenation. Following a similar strategy as in our recent work on alcohol amination 54 , we computed the C and O adsorption energies for 294 dilute alloys and evaluated their credentials for dehydrogenation (Supplementary Table 9 ). As shown in Supplementary Fig.…”
Acceptorless dehydrogenation into carbonyls and molecular hydrogen is an attractive strategy to valorize (biobased) alcohols. Using 2-octanol dehydrogenation as benchmark reaction in a continuous reactor, a library of metal-supported catalysts is tested to validate the predictive level of catalytic activity for combined DFT and micro-kinetic modeling. Based on a series of transition metals, scaling relations are determined as a function of two descriptors, i.e. the surface binding energies of atomic carbon and oxygen. Then, a volcano-shape relation based on both descriptors is derived, paving the way to further optimization of active catalysts. Evaluation of 294 diluted alloys but also a series of carbides and nitrides with the volcano map identified 12 promising candidates with potentially improved activity for alcohol dehydrogenation, which provides useful guidance for experimental catalyst design. Further screening identifies β-Mo2N and γ-Mo2N exposing mostly (001) and (100) facets as potential candidates for alcohol dehydrogenation.
“…This network involving many possible reaction pathways imposes a great challenge for the selective synthesis of primary amines. Moreover, different from simple hydrogenation, reductive amination requires the catalyst to be able to survive in the presence of excess ammonia and amine, which are usually strongly adsorbed on metal catalysts and become a possible poison for hydrogenation reactions 20 . Fig.…”
Single-atom catalysts (SACs) have emerged as a frontier in heterogeneous catalysis due to the well-defined active site structure and the maximized metal atom utilization. Nevertheless, the robustness of SACs remains a critical concern for practical applications. Herein, we report a highly active, selective and robust Ru SAC which was synthesized by pyrolysis of ruthenium acetylacetonate and N/C precursors at 900 °C in N2 followed by treatment at 800 °C in NH3. The resultant Ru1-N3 structure exhibits moderate capability for hydrogen activation even in excess NH3, which enables the effective modulation between transimination and hydrogenation activity in the reductive amination of aldehydes/ketones towards primary amines. As a consequence, it shows superior amine productivity, unrivalled resistance against CO and sulfur, and unexpectedly high stability under harsh hydrotreating conditions compared to most SACs and nanocatalysts. This SAC strategy will open an avenue towards the rational design of highly selective and robust catalysts for other demanding transformations.
“…For instance, exchanging 2H-MoS 2 for 1T-MoS 2 results in a marked increase toward the hydrogen evolution reaction ( 18 , 19 ). Considering the advantage of TMDs being able to control the atomic-scale structure, phase engineering may also open possibilities to control the selectivity of multielectron/proton reactions with multiple possible products, such as CO 2 reduction ( 20 – 23 ), denitrification (NO 3 − /NO 2 − reduction) ( 24 – 26 ), and the electrosynthesis of functional molecules ( 27 – 30 ). Selectivity is a critical requirement for cascade catalysis, one-pot reaction systems, and multistep catalytic processes, and strategies to guide the complex chemical reaction network toward the desired end product are necessary ( 31 , 32 ).…”
Molybdenum sulfide (MoS2) is the most widely studied transition-metal dichalcogenide (TMDs) and phase engineering can markedly improve its electrocatalytic activity. However, the selectivity toward desired products remains poorly explored, limiting its application in complex chemical reactions. Here we report how phase engineering of MoS2 significantly improves the selectivity for nitrite reduction to nitrous oxide, a critical process in biological denitrification, using continuous-wave and pulsed electron paramagnetic resonance spectroscopy. We reveal that metallic 1T-MoS2 has a protonation site with a pKa of ∼5.5, where the proton is located ∼3.26 Å from redox-active Mo site. This protonation site is unique to 1T-MoS2 and induces sequential proton−electron transfer which inhibits ammonium formation while promoting nitrous oxide production, as confirmed by the pH-dependent selectivity and deuterium kinetic isotope effect. This is atomic-scale evidence of phase-dependent selectivity on MoS2, expanding the application of TMDs to selective electrocatalysis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
