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Ethanol is a high‐value chemical that can be produced from syngas derived from fossil or renewable resources. Silica‐supported catalysts based on Rh are reported to show the best performance so far. We report a comprehensive investigation for influence of catalyst composition on performance in syngas conversion to ethanol. We evaluate 53 different silica‐supported catalysts with a varying degree of Rh, Mn, Ir, Li and Ti, via high‐throughput testing. Correlation analysis reveals that Li and Ir tend to increase the selectivity to C2+ oxygenates, and catalysts with a 0.95 molar ratio of Rh : Mn show a tendency for high CO conversion. The composition 2.8Rh, 0.45Mn, 1.3Ir, 0.04Li, where the numbers indicate weight percentage, is identified to yield one of the highest C2+ oxygenate values reported in the literature so far. Moreover, combining this catalyst with a hydrogenation catalyst and converting C2+ oxygenates to ethanol, provides one of the highest ethanol yields reported so far in literature. [ABSTRACT FROM AUTHOR]

The direct conversion of synthesis gas could open up economically viable routes for the efficient production of ethanol. RhMn/SiO2 represents one of the most active systems reported thus far. Potential improvements were reported by added dopants, i.e., Ir, Ti, and Li. Yet, combining these elements leads to contradicting results, owing to the complexity of the interactions in a multi-promoted system. This complexity is often encountered in heterogeneous catalysis. We report a systematic data-driven approach for the assessment of complex multi-promoter interactions based on a combination of design-of-experiment, high-throughput experimentation, statistical analysis, and mechanistic assessment. We illustrate this approach for the system RhMn/SiO2 promoted with Ir, Li, and Ti. Using this approach, we investigate the impact of promoters' interactions on a mechanistic level. Our analysis depicts the means to learn hidden correlations in the performance data and, additionally, high performance for ethanol yield for the RhMnIr/SiO2 catalyst. The method presented outlines an efficient way to also elucidate co-promoter interactions in other complex environments. [ABSTRACT FROM AUTHOR]

The direct conversion of syngas to ethanol, typically using promoted Rh catalysts, is a cornerstone reaction in CO2 utilization and hydrogen storage technologies. A rational catalyst development requires a detailed structural understanding of the activated catalyst and the role of promoters in driving chemoselectivity. Herein, we report a comprehensive atomic‐scale study of metal–promoter interactions in silica‐supported Rh, Rh–Mn, and Rh–Mn–Fe catalysts by aberration‐corrected (AC) TEM. While the catalytic reaction leads to the formation of a Rh carbide phase in the Rh–Mn/SiO2 catalyst, the addition of Fe results in the formation of bimetallic Rh–Fe alloys, which further improves the selectivity and prevents the carbide formation. In all promoted catalysts, Mn is present as an oxide decorating the metal particles. Based on the atomic insight obtained, structural and electronic modifications induced by promoters are revealed and a basis for refined theoretical models is provided. [ABSTRACT FROM AUTHOR]

The first molecular carbonyl RhMn cluster Na2[Rh3Mn3(CO)18] 2 with highly labile CO ligands and predefined Rh‐Mn bonds could be realized and successfully used for the preparation of the silica (davisil)‐supported RhMnOx catalysts for the conversion of syngas (CO, H2) to ethanol (StE); it has been synthesized through the salt metathesis reaction of RhCl3 with Na[Mn(CO)5] 1 and isolated in 49 % yields. The dianionic Rh3Mn3 cluster core of 2 acts as a molecular single‐source precursor (SSP) for the low‐temperature preparation of selective high‐performance RhMnOx catalysts. Impregnation of 2 on silica (davisil) led to three different silica‐supported RhMnOx catalysts with dispersed Rh nanoparticles tightly surrounded by a MnOx matrix. By using this molecular SSP approach, Rh and MnOx are located in close proximity on the oxide support. Therefore, the number of tilted CO adsorption sites at the RhMnOx interface increased leading to a significant enhancement in selectivity and performance. Investigations on the spent catalysts after several hours time‐on‐stream revealed the influence of rhodium carbide RhCx formation on the long‐term stability. Catalysts Birth. The first carbonyl RhMn cluster Na2[Rh3Mn3(CO)18] has been synthesized, structurally characterized and utilized as well‐defined molecular single‐source precursor (SSP) for the low‐temperature preparation of selective high‐performance RhMn catalysts for the conversion of syngas to ethanol (StE). Highly dispersed Rh nanoparticles in a tightly surrounded MnOx matrix lead to a superior selectivity towards ethanol. [ABSTRACT FROM AUTHOR]