Enhancing of catalytic properties of vanadia via surface doping with phosphorus using atomic layer deposition

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in J. Vac. Sci. Technol. A 34, 01A135 (2016) and may be found at https://doi.org/10.1116/1.4936390.Atomic layer deposition is mainly used to deposit thin films on flat substrates. Here, the authors deposit a submonolayer of phosphorus on V2O5 in the form of catalyst powder. The goal is to prepare a model catalyst related to the vanadyl pyrophosphate catalyst (VO)2P2O7 industrially used for the oxidation of n-butane to maleic anhydride. The oxidation state of vanadium in vanadyl pyrophosphate is 4+. In literature, it was shown that the surface of vanadyl pyrophosphate contains V5+ and is enriched in phosphorus under reaction conditions. On account of this, V2O5 with the oxidation state of 5+ for vanadium partially covered with phosphorus can be regarded as a suitable model catalyst. The catalytic performance of the model catalyst prepared via atomic layer deposition was measured and compared to the performance of catalysts prepared via incipient wetness impregnation and the original V2O5 substrate. It could be clearly shown that the dedicated deposition of phosphorus by atomic layer deposition enhances the catalytic performance of V2O5 by suppression of total oxidation reactions, thereby increasing the selectivity to maleic anhydride.DFG, 53182490, EXC 314: Unifying Concepts in Catalysi

A New Synthetic Amphidiploid in Cucumis from a C. sativus x C. hystrix F1 Interspecific Hybrid

CT. A synthetic amphidiploid was developed through organogenesis in tissue culturefrom an interspecific F1hybrid betweenCucumis sativus L. andC. hystrix Chakr. The resultsfrom flow cytometry indicated that, on average, 7.3% of the regenerants with unique morphology were chromosome-doubled F1hybrids. The 2C DNA content of the original F1hybrid was1.17 pg, and the 4C DNA content was 2.35 pg. Frequency of chromosome doubling between thetwo genotypes used in this study varied considerably

In situ electrochemical cells to study the oxygen evolution reaction by near ambient pressure x-ray photoelectron spectroscopy

In this contribution, we report the development of in situ electrochemical cells based on proton exchange membranes suitable for studying interfacial structural dynamics of energy materials under operation by near ambient pressure X-ray photoelectron spectroscopy. We will present both the first design of a batch-type two-electrode cell prototype and the improvements attained with a continuous flow three-electrode cell. Examples of both sputtered metal films and carbon-supported metal nanostructures are included demonstrating the high flexibility of the cells to study energy materials. Our immediate focus was on the study of the oxygen evolution reaction, however, the methods described herein can be broadly applied to reactions relevant in energy conversion and storage devices

Phase coexistence of multiple copper oxides on AgCu catalysts during ethylene epoxidation

Alloy catalysts under reaction conditions are complex entities. In oxidizing atmospheres, multiple phases can coexist on a catalyst s surface as a result of phase segregation and preferential oxidation. Such a scenario can result in unusual substoichiometric and metastable phases that could play important roles in catalytic processes. For instance, AgCu alloys known to exhibit enhanced epoxide selectivity in partial oxidation of ethylene form an oxide like surface structure under reaction conditions. Under these conditions, copper oxides are stable, while silver oxides are not. Consequently, copper segregates to the alloy s surface and forms an oxide overlayer. Little is known about the structure or function of such overlayers, and it is unknown whether they play an active role in the catalyst s enhanced selectivity. In order to develop a clearer picture of such catalysts, the current work utilizes several in situ spectroscopic and microscopic techniques to examine the copper oxide phases that form when AgCu is exposed to epoxidation conditions. It is found that several forms of oxidic Cu coexist simultaneously on the active catalyst s surface, namely, CuO, Cu2O, and some previously unreported form of oxidized Cu, referred to here as CuxOy. Online product analysis, performed during the in situ spectroscopic measurements, shows that increased epoxide selectivity is correlated with the presence of mixed copper oxidation states and the presence of the CuxOy species. These results support previous theoretical predictions that oxidic copper overlayers on silver play an active role in epoxidation. These results furthermore emphasize the need for in situ spectromicroscopic methods to understand the complexity of alloy catalyst

Quorum Sensing Primes the Oxidative Stress Response in the Insect Endosymbiont, Sodalis glossinidius

quorum sensing system relies on the function of two regulatory proteins; SogI (a LuxI homolog) synthesizes a signaling molecule, characterized as N-(3-oxohexanoyl) homoserine lactone (OHHL), and SogR1 (a LuxR homolog) interacts with OHHL to modulate transcription of specific target genes. and SOPE. and SOPE indicates the potential for neofunctionalization to occur during the process of genome degeneration

Influence of the method of heat input in carrot drying on the kinetics of the process

Badano wpływ sposobu doprowadzania ciepła (strumieniem gorącego powietrza o temperaturze 70, 100 i 150°C przez 4 min lub promieniowania mikrofalowego ok. 250 W przez 0,5 i 1 minutę) do pojedynczych plastrów marchwi przed procesem suszenia w warunkach konwekcji naturalnej na kinetykę procesu. Określono zależność szybkości suszenia w temperaturze 70 i 106°C w funkcji zawartości wody po zastosowaniu różnych metod wstępnego ogrzewania oraz określono statystycznie charakter tych zmian w przedziałach zawartości wody.Influence of the method of heat input (stream of hot air at temperature 70, 100 and 150°C for 4 minutes or microwave radiation circa 250 W for 0.5 and 1 minute) to single carrot slices before the drying process in natural convection conditions on the process kinetics was analysed. The relation between drying speed at temperature 70 and 106°C as function of water content after application of various methods of preliminary heating was determined and character of these changes in water content ranges was determined