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  Wissenschaftliche Artikel aus der Fachliteratur.

3 Einträge
Abstract

Methanol synthesis from syngas (CO/H2 mixtures) is one of the largest manmade chemical processes with annual production reaching 100 million tons. The current industrial method proceeds at high temperatures (200–300 °C) and pressures (50–100 atm) using a copper–zinc-based heterogeneous catalyst. In contrast, here, we report a molecularly defined manganese catalyst that allows for low-temperature/low-pressure (120–150 °C, 50 bar) carbon monoxide hydrogenation to methanol. This new approach was evaluated and optimized by quantum mechanical simulations virtual high-throughput screenings. Crucial for this achievement is the use of amine-based promoters, which capture carbon monoxide to give formamide intermediates, which then undergo manganese-catalyzed hydrogenolysis, regenerating the promoter. Following this conceptually new approach, high selectivity toward methanol and catalyst turnover numbers (up to 3170) was achieved. The proposed general catalytic cycle for methanol synthesis is supported by model studies and detailed spectroscopic investigations.

Autoren

Pavel Ryabchuk, Kenta Stier, Kathrin Junge, Marek P. Checinski, Matthias Beller

Quelle

Pavel Ryabchuk, Kenta Stier, Kathrin Junge, Marek P. Checinski, and Matthias Beller; Journal of the American Chemical Society 2019 141 (42), 16923-16929, DOI: 10.1021/jacs.9b08990

Abstract

The electrocatalytic reduction of carbon dioxide (CO2RR) to valuable bulk chemicals is set to become a vital factor in the prevention of environmental pollution and the selective storage of sustainable energy. Inspired by structural analogues to the active site of the enzyme CODHNi, we envisioned that bulk Fe/Ni sulfides would enable the efficient reduction of CO2. By careful adjustment of the process conditions, we demonstrate that pentlandite (Fe4.5Ni4.5S8) electrodes, in addition to HER, also support the CO2RR reaching a peak faradaic efficiency of 87% and 13% for the formation of CO and methane, respectively at 3 mA cm−2. The choice of solvent, the presence of water/protons and CO2 solubility are identified as key-properties to adjust the balance between HER and CO2RR in favour of the latter. Such experiments can thus serve as model reactions to elucidate a potential catalyst within gas diffusion electrodes.

Autoren

Stefan Piontek, Kai junge Puring, Daniel Siegmund, Mathias Smialkowski, Ilya Sinev, David Tetzlaff, Beatriz Roldan Cuenya und Ulf-Peter Apfel

Quelle

Piontek, K. junge Puring, D. Siegmund, M. Smialkowski, I. Sinev, B. Roldan Cuenya, U.-P. Apfel, „Bio-Inspired Design: Bulk Iron-Nickel Sulfide Allows for Efficient Solvent-dependent CO2 Reduction.“, Chem. Sci. 2019, 10, 1075–1081, DOI: 10.1039/C8SC03555E

Abstract

The electrochemical reduction of CO2 is an attractive strategy towards the mitigation of environmental pollution and production of bulk chemicals as well as fuels by renewables. The bimetallic sulfide Fe4.5Ni4.5S8 (pentlandite) was recently reported as a cheap and robust catalyst for electrochemical water splitting, as well as for CO2 reduction with a solvent‐dependent product selectivity. Inspired by numerous reports on monometallic sulfoselenides and selenides revealing higher catalytic activity for the CO2 reduction reaction (CO2RR) than their sulfide counterparts, the authors investigated the influence of stepwise S/Se exchange in seleno‐pentlandites Fe4.5Ni4.5S8‐YSeY (Y=1–5) and their ability to act as CO2 reducing catalysts. It is demonstrated that the incorporation of higher equivalents of selenium favors the CO2RR with Fe4.5Ni4.5S4Se4 revealing the highest activity for CO formation. Under galvanostatic conditions in acetonitrile, Fe4.5Ni4.5S4Se4 generates CO with a Faradaic Efficiency close to 100 % at applied current densities of −50 mA cm−2 and −100 mA cm−2. This work offers insight into the tunability of the pentlandite based electrocatalysts for the CO2 reduction reaction.

Autoren

Kevinjeorjios Pellumbi, Mathias Smialkowski, Dr. Daniel Siegmund, Prof. Dr. Ulf‐Peter Apfel

Quelle

K. Pellumbi, M. Smialkowski, D. Siegmund, U.-P. Apfel, „Enhancing the CO2-electroreduction of Fe/Ni-pentlandite Catalysts by S/Se exchange“, Chem. Eur. J. 2020, DOI: 10.1002/chem.202001289

Patente

  Eingetragene Patente.

1 Eintrag
Zusammenfassung

Die Erfindung betrifft ein Verfahren zur katalysierten Umsetzung von CO und H2. Der Katalysator enthält ein Übergangsmetall als zentrales Ion und mindestens einen Lewis-basischen Liganden. Zusammen mit mindestens einem nukleophilen Promotor werden CO und H2 zu dem Produkt Methanol umgewandelt.

Autoren

M. Checinski, M. Beller, P. Ryabchuk, K. Junge

Quelle

DE102018133689A1, WO002020136003A1