MnxCo3‐x[Co(CN)6]2 Prussian blue analogues were synthesized with Mn : Co ratios in the range from 7 : 10 to 1 : 11 and pyrolyzed at 600 °C to obtain a highly nitrogen‐ and oxygen‐functionalized carbon matrix with embedded reduced Mn and Co species. These catalyst precursors were applied in the CO hydrogenation to higher alcohols at 260 °C and a pressure of 60 bar using a H2/CO ratio of 1. Metallic Co0 formed during pyrolysis was partially transformed into Co2C under reaction conditions. With increasing Co content CO conversion increased up to 10.6 % reaching a total alcohol selectivity of 19 %. Gas chromatograms revealed the expected formation of primary short‐chain alcohols, but also of secondary alcohols, acetic acid and propionaldehyde indicating olefin hydration, carbonylation and hydroformylation as reaction pathways, respectively. The obtained hydrocarbon fractions had a very high olefinicity, which is beneficial for both olefin hydration to secondary alcohols catalyzed by adsorbed carboxylic acids and for hydroformylation. Whereas the carbide‐based reaction pathway and the reductive hydroformylation are assumed to occur at the Co2C/Co0 interface, carbonylation is presumably catalyzed by an additional Co‐based active site. Thus, a unique class of multifunctional catalysts was obtained with highly promising properties bridging the gap between heterogeneous and homogeneous catalysis.
Multi-metal electrocatalysts provide nearly unlimited catalytic possibilities arising from synergistic element interactions. We propose a polymer/metal precursor spraying technique that can easily be adapted to produce a large variety of compositional different multi-metal catalyst materials. To demonstrate this, 11 catalysts were synthesized, characterized, and investigated for the oxygen evolution reaction (OER). Further investigation of the most active OER catalyst, namely CoNiFeMoCr, revealed a polycrystalline structure, and operando Raman measurements indicate that multiple active sites are participating in the reaction. Moreover, Ni foam-supported CoNiFeMoCr electrodes were developed and applied for water splitting in flow-through electrolysis cells with electrolyte gaps and in zero-gap membrane electrode assembly (MEA) configurations. The proposed alkaline MEA-type electrolyzers reached up to 3 A cm À 2 , and 24 h measurements demonstrated no loss of current density of 1 A cm À 2 .
The reaction pathways of higher alcohol synthesis over a bulk CoÀ Cu catalyst (Co : Cu = 2 : 1) were investigated by applying high-pressure pulse experiments as a surface-sensitive operando method at 280 °C and 60 bar. Using high-pressure CO and H 2 pulses in a syngas flow with a H 2 :CO ratio of 1, it was shown that the surface of the working 2CoCu catalyst is saturated with adsorbed CO, but not with adsorbed atomic hydrogen, because only the H 2 pulses increased the yields of all alcohols and alkanes. The reverse water gas shift reaction (WGSR) was investigated by pulsing CO 2 . The CO 2 pulses poisoned the formation of methanol, ethanol, and 1-propanol, and the absence of significant CO and H 2 O responses indicates that the WGSR is not efficiently catalyzed by the applied 2CoCu catalyst excluding the presence of exposed Cu 0 sites. A series of ethylene pulses showed that when a threshold mole fraction of ethylene of about 1 vol % is surpassed, 2CoCu is an active catalyst for the hydroformylation of ethylene to 1-propanol pointing to the presence of highly coordinatively unsaturated Co sites.
Multimetall-Elektrokatalysatoren bieten nahezu unbegrenzte katalytische Möglichkeiten, die sich aus synergistischen Elementwechselwirkungen ergeben. Wir schlagen eine Polymer/Metallsalz-Sprühtechnik vor, die leicht angepasst werden kann, um eine große Vielfalt von Multimetall-Katalysatormaterialien mit unterschiedlicher Zusammensetzung herzustellen. Um dies zu demonstrieren, wurden 11 Katalysatoren synthetisiert, charakterisiert und für die Sauerstoffentwicklungsreaktion (OER) untersucht. Weitere Untersuchungen des aktivsten OER-Katalysators, nämlich CoNiFeMoCr, ergaben eine polykristalline Struktur, und Operando-Raman-Messungen deuten darauf hin, dass mehrere aktive Zentren an der Reaktion beteiligt sind. Darüber hinaus wurden auf Ni-Schaum basierende CoNiFeMoCr-Elektroden entwickelt und für die Wasserspaltung in Durchflusselektrolysezellen mit Elektrolytspalten und in "zero-gap" Membran-Elektroden-Anordnungen (MEA) eingesetzt. Die alkalischen MEA-Elektrolyseure erreichten bis zu 3 A cm À 2 , und 24-Stunden-Messungen zeigten keinen Verlust der Stromdichte von 1 A cm À 2 .
The catalytic effect of minerals on biomass conversion was studied focusing on Fe as well as alkali and alkaline earth metals as the metallic inorganic elements typically present in minerals found in biomass. A mineral-free reference hydrochar and an analogous char material based on cellulose were systematically doped with sulfates of the different metallic inorganic elements in various amounts via impregnation, thereby excluding differences originating from the counterion and the carbon matrix. Thermogravimetric reactivity measurements were performed in diluted O 2 and CO 2 , and the derivative thermogravimetry curves were fitted using the random pore model. This procedure enabled a quantification of the apparent activation energy decrease due to doping as well as the influence of doping on the carbon structural parameter. Fe sulfate was always among the most active minerals, and alkali metal sulfates were typically more active than alkaline earth metal sulfates. The only exception was the high activity of very small Ca sulfate loadings during gasification. A saturation behavior of the kinetic parameter upon increasing the mineral loading was observed. The Langmuirtype modeling of this dependence further revealed that catalytically influenced devolatilization results in a char with higher oxidation reactivity, whereas for gasification, thermal annealing dominates. The systematically derived parameters provide a comprehensive description of catalytic effects, taking into account the type of mineral, the applied loading, the used atmosphere, and the fuel morphology. The derived activation energies can be used to include catalytic effects into combustion models.
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