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.

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

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 CODH_Ni, 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 CORR in favour of the latter. Such experiments can thus serve as model reactions to elucidate a potential catalyst within gas diffusion electrodes.

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

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 Fe_4.5Ni_4.5S₈ (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 Fe_4.5Ni_4.5S₈‐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 Fe_4.5Ni_4.5S₄Se₄ revealing the highest activity for CO formation. Under galvanostatic conditions in acetonitrile, Fe_4.5Ni_4.5S₄Se₄ 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.

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

A manganese pincer complex Mn-2 for the homogeneously catalysed conversion of CO/H2 to methanol was developed using a novel PNP ligand design. Compared to the previous state-of-the-art catalyst system Mn-1, the presented Mn-2 with different substituents at the P-atoms led to a significant increase of the reaction rate (TOF up to >1600 h−1).

Gordon Neitzel, Dr. Rauf Razzaq, Dr. Anke Spannenberg, Kenta Stier, Dr. Marek P. Checinski, Dr. Ralf Jackstell, Prof. Dr. Matthias Beller