Carbonyl Recycling Limits Productive Ethanol Formation during Syngas Conversion on Rh(211): A First-Principles Microkinetic Analysis
- 1School of Innovation and Sustainability
- 2De La Salle University
- 3Center for Quantum Information and Quantum Biology, University of Osaka, 1–2 Machikaneyama-cho, Toyonaka, Osaka, Japan, 560-0043
Abstract
Higher alcohol synthesis from syngas on Rh involves a highly branched and reversible reaction network in which formation of a C–C bond does not necessarily result in productive higher-alcohol synthesis. Here, a thermodynamically consistent first-principles mean-field microkinetic model is constructed to determine how carbon is partitioned among methane, methanol, ethanol, and highercarbon intermediates under steady-state conditions. Across a 100-point temperature–pressure domain, the model exhibits a pronounced activity–selectivity trade-off: conditions that increase turnover progressively favor methane and methanol over ethanol. Reaction-flux analysis reveals that CO insertion provides the dominant entry into the C 2 carbonyl manifold, but 79–94% of this carbonyl flux is recycled toward the C 1 pool across representative kinetic regimes rather than converted productively to ethanol. Consequently, the elementary C–C coupling reactions carry substantial flux while exhibiting relatively small degrees of rate control. Instead, downstream ethoxy hydrogenation becomes increasingly rate controlling, while methane formation and oxygen-removal chemistry strongly influence ethanol productivity. CHO insertion, despite its favorable intrinsic forward barrier, changes from a productive C–C-forming pathway at low activity to a net recycling pathway at high activity, demonstrating that isolated activation barriers do not determine steady-state pathway utilization. Methanol additionally constitutes a major competing sink for oxygenated C 1 carbon. These results show that improving Rh-based higheralcohol synthesis requires not only promoting C–C coupling but also suppressing carbonyl recycling and kinetically trapping C 2 intermediates along the productive ethanol pathway.
Related
- Functional Polymer Catalysts for CO2 Capture and Conversion: Design Principles, Applications, and Future Perspectives
- Excitonic Physics in Emerging 2D Semiconductors: A First-Principles Many-Body Perspective from Photodetection to Solar Energy Conversion
- Lead-free quaternary chalcogenide NaZrCuS3 for efficient thermoelectric energy conversion: insights from first-principles and Boltzmann transport
- Uncovering Heterogeneous Energetic Trajectories in NiFe Oxygen Evolution Electrocatalysis through Integrated Raman, Electrochemical and Microkinetic Analysis
- Aggregation-Driven Self-Inhibition of Grignard Reagents: Insights from DFT and Microkinetic Modeling
BibTeX
@misc{arevalo2026carbonyl,
title = {{Carbonyl Recycling Limits Productive Ethanol Formation during Syngas Conversion on Rh(211): A First-Principles Microkinetic Analysis}},
author = {Ryan Lacdao Arevalo and Hiroshi Nakanishi},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008804/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008804/v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Carbonyl Recycling Limits Productive Ethanol Formation during Syngas Conversion on Rh(211): A First-Principles Microkinetic Analysis
AU - Ryan Lacdao Arevalo
AU - Hiroshi Nakanishi
PY - 2026
DA - 2026/09/14
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008804/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008804/v1
AB - Higher alcohol synthesis from syngas on Rh involves a highly branched and reversible reaction network in which formation of a C–C bond does not necessarily result in productive higher-alcohol synthesis. Here, a thermodynamically consistent first-principles mean-field microkinetic model is constructed to determine how carbon is partitioned among methane, methanol, ethanol, and highercarbon intermediates under steady-state conditions. Across a 100-point temperature–pressure domain, the model exhibits a pronounced activity–selectivity trade-off: conditions that increase turnover progressively favor methane and methanol over ethanol. Reaction-flux analysis reveals that CO insertion provides the dominant entry into the C 2 carbonyl manifold, but 79–94% of this carbonyl flux is recycled toward the C 1 pool across representative kinetic regimes rather than converted productively to ethanol. Consequently, the elementary C–C coupling reactions carry substantial flux while exhibiting relatively small degrees of rate control. Instead, downstream ethoxy hydrogenation becomes increasingly rate controlling, while methane formation and oxygen-removal chemistry strongly influence ethanol productivity. CHO insertion, despite its favorable intrinsic forward barrier, changes from a productive C–C-forming pathway at low activity to a net recycling pathway at high activity, demonstrating that isolated activation barriers do not determine steady-state pathway utilization. Methanol additionally constitutes a major competing sink for oxygenated C 1 carbon. These results show that improving Rh-based higheralcohol synthesis requires not only promoting C–C coupling but also suppressing carbonyl recycling and kinetically trapping C 2 intermediates along the productive ethanol pathway.
ER -