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When utilizing industrial exhaust gases for methanol synthesis, catalyst poisoning is an important issue. Long‐term in‐situ poisoning under industrially relevant conditions with sulfur‐containing molecules co‐fed into the feed gas flow and supplemented by extensive post‐mortem characterization of the catalyst bed is an efficient way to deepen the understanding of the poisoning mechanism and the different poisoning strengths of H2S, thiophene, and COS reported in literature. Unfortunately, such studies are rare due to the corrosive effects of sulfur compounds on typical lab‐scale flow setups. Therefore, this communication provides a detailed description of a setup built for poisoning studies using sulfur‐containing molecules under industrially relevant methanol synthesis conditions. [ABSTRACT FROM AUTHOR]

Dielectric barrier discharges (DBDs) are frequently utilized in various gas conversion processes. For industrial applications a low flow resistance and scalability are crucial. In this study a tenfold scaled‐up reactor based on a surface dielectric barrier discharge (SDBD) was employed for the removal of oxygen traces from H2/N2/O2 gas mixtures. The conversion efficiency of the reactor with ten electrode configurations was investigated for different admixtures of O2, and high degrees of conversion were observed that decreased with increasing flow rate, but remained constant when raising the pressure to 2 bar(g). A new generator based on silicon carbide field‐effect transistors (SiC‐FETs) was used and compared to a generator based on classical metal oxide semiconductor field‐effect transistors (MOS‐FETs). [ABSTRACT FROM AUTHOR]

Industrial implementation of the heterogeneously catalyzed CO hydrogenation to higher alcohols is highly desired, but deeper insights into the reaction mechanisms and active sites are still needed. This review summarizes the established and well‐investigated cobalt‐based catalysts and the mechanisms resulting in oxygenate formation. Recently, a cobalt‐based system derived from Mn‐Co‐based Prussian blue analogs by pyrolysis has shown great potential for higher‐alcohol synthesis. In addition to the heterogeneously catalyzed reaction pathways involved in Fischer‐Tropsch synthesis and methanol synthesis, the homogeneously catalyzed reaction pathways like reductive olefin hydroformylation and reductive primary alcohol carbonylation were found to play a key role. [ABSTRACT FROM AUTHOR]

The sustainable synthesis of long carbon chain molecules from carbon dioxide, water and electricity relies on the development of waste‐free, highly selective C−C bond forming reactions. An example for such a power‐to‐chemicals process is the industrial‐scale fermentation for the production of hexanoic acid. Herein, we describe how this product is transformed into 6‐undecanone via decarboxylative ketonization using a heterogeneous manganese oxide/silica catalyst. The reaction reaches full conversion with near‐complete selectivity when carried out in a continuous flow reactor, requires no solvent or carrier gas, and releases carbon dioxide and water as the only by‐products. The reactor was operated for several weeks with no loss of reactivity, producing 7 kg of 6‐undecanone from 10 g of catalyst and achieving a productivity of 1.135 kg per litre of reactor volume per hour. 6‐Undecanone and other long‐chain ketones accessible this way can be hydrogenated to industrially meaningful alkanes, or converted into valuable fatty acids via a hydrogenation/elimination/isomerizing hydrocarboxylation sequence. [ABSTRACT FROM AUTHOR]

Anaerobic thermal-assisted photocatalytic methanol conversion in the gas phase in the presence of water vapor has been suggested as an interesting way to generate formaldehyde as a valuable coupled product in addition to H2 production. Here, the reaction mechanism and photocatalyst deactivation are investigated in detail using in situ diffuse reflectance infrared fourier transform (DRIFTS) and electron paramagnetic resonance (EPR) spectroscopy. EPR shows that paramagnetic oxygen vacancies are not involved in the reaction mechanism over undoped SrTiO3. Instead, on an optimized 0.1 wt% Pt/SrTiO3 photocatalyst, methoxy species are formed by dissociative adsorption of methanol leading to formaldehyde formation while the formation of CO, CO2 (via a formate intermediate) and methyl formate occurs through three concurrent reactions from formyl species. Our findings suggest that CO adsorbed on Pt is a spectator species not perturbing the reaction kinetics, and deactivation is shown to be strongly correlated with the accumulation of formate groups on SrTiO3, which is more pronounced at high reaction temperatures. The mechanistic understanding provided here forms the basis for the further optimization of photocatalysts to increase methanol conversion and improve formaldehyde selectivity. [ABSTRACT FROM AUTHOR]

Continuous methanol photooxidation in the gas phase is a promising method to produce valuable chemicals like formaldehyde or methyl formate in addition to hydrogen under mild conditions. The influence of the reaction conditions on the selectivity of methanol oxidation to formaldehyde is studied using a heated flat‐plate flow photoreactor illuminated by an LED array (λmax = 368 nm) and Pt‐modified SrTiO3. A combination of online analytical methods allowed to quantify all gaseous products during extended time‐on‐stream (> 48 h TOS). The selectivity to formaldehyde is found to be primarily determined by the residence time and the process temperature. At a low methanol to water ratio, methanol conversion and evolution of CO2 are favored, whereas the light intensity primarily influenced the apparent quantum yield from 5.1 to 1.8% at 9.36 to 52.93 mW cm−2, respectively, and the methanol conversion thus determining the economic efficiency of the process. Operation temperatures higher than 110 °C resulted in a strong deactivation of the catalyst while simultaneously the formation of CO at the expense of formaldehyde selectivity is favored. This study demonstrates the importance of understanding the influence of relevant reaction conditions and the potential of selective photocatalytic gas‐phase oxidation of small molecules. [ABSTRACT FROM AUTHOR]