ORCID Profile
0000-0002-8205-2714
Current Organisations
University of Oslo
,
Universität Leipzig
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Publisher: Wiley
Date: 25-04-2018
Abstract: The possibility of efficient water electrooxidation sustained by continuous (re)generation of catalysts derived from the oxidative electrodeposition of transition-metal contaminants is examined herein for three natural water s les from Australia and China. The metal composition of the solutions has been determined by inductively coupled plasma optical emission spectrometry, and a range of strategies to produce water-splitting catalysts by means of in situ electrodeposition have been applied. The performance of the resulting electrocatalysts is below the state-of-the-art level owing to large amounts of impurities in the solutions and non-optimal concentrations of naturally available catalyst precursors. Nevertheless, these studies have identified the FePb-based system as a rare ex le of an electrocatalyst for water oxidation that forms in situ and maintains reasonable activity (≥4.5 mA cm
Publisher: Wiley
Date: 2022
Publisher: Wiley
Date: 31-08-2021
Abstract: Das Verständnis der Katalysatordesaktivierung durch Verkokung ist entscheidend für ein wissensbasiertes Katalysator‐ und Prozessdesign bei Reaktionen mit Kohlenstoffverbindungen. Die Katalysatorverkokung wird dabei typischerweise durch Post‐Mortem‐Analyse untersucht. In der vorliegenden Arbeit wird ptychographische Röntgentomographie (PXCT) zur Analyse von künstlich verkokten Ni/Al 2 O 3 ‐Katalysatoren für die CO 2 ‐Methansierung und CH 4 ‐Trockenreformierung verwendet. PXCT liefert dabei 3D‐Informationen der lokalen Elektronendichte mit ca. 80 nm Auflösung und ermöglicht somit die Visualisierung und Untersuchung der Ausprägung der Verkokung in Katalysatorpartikeln mit einem Durchmesser von ca. 40 μm. Die Verkokung wurde hauptsächlich im nanoporösen Festkörper identifiziert und konnte nicht in den aufgelösten Makroporen gefunden werden. Die Kohlenstoffbildung wurde unabhängig dazu mittels operando Raman‐Spektroskopie bestätigt. PXCT wird als aufkommende Charakterisierungstechnik hervorgehoben, die eine nanoskalige Identifizierung, Lokalisierung und möglicherweise Quantifizierung von verschiedenen Desaktivierungsphänomenen mit 3D‐Auflösung in kompletten Katalysatorpartikeln ermöglicht.
Publisher: Wiley
Date: 31-08-2021
Abstract: Understanding catalyst deactivation by coking is crucial for knowledge‐based catalyst and process design in reactions with carbonaceous species. Post‐mortem analysis of catalyst coking is often performed by bulk characterization methods. Here, hard X‐ray ptychographic computed tomography (PXCT) was used to study Ni/Al 2 O 3 catalysts for CO 2 methanation and CH 4 dry reforming after artificial coking treatment. PXCT generated quantitative 3D maps of local electron density at ca. 80 nm resolution, allowing to visualize and evaluate the severity of coking in entire catalyst particles of ca. 40 μm diameter. Coking was primarily revealed in the nanoporous solid, which was not detectable in resolved macropores. Coke formation was independently confirmed by operando Raman spectroscopy. PXCT is highlighted as an emerging characterization tool for nanoscale identification, co‐localization, and potentially quantification of deactivation phenomena in 3D space within entire catalyst particles.
Publisher: Wiley
Date: 20-01-2022
Abstract: The synthesis of hierarchically porous materials usually requires complex experimental procedures, often based around extensive trial and error approaches. One common synthesis strategy is the sol–gel method, although the relation between synthesis parameters, material structure and function has not been widely explored. Here, in situ 2D hard X‐ray ptychography (XRP) and 3D ptychographic X‐ray computed tomography (PXCT) are applied to monitor the development of hierarchical porosity in Ni/Al 2 O 3 and Al 2 O 3 catalysts with connected meso‐ and macropore networks. In situ XRP allows to follow textural changes of a dried gel Ni/Al 2 O 3 s le as a function of temperature during calcination, activation and CO 2 methanation reaction. Complementary PXCT studies on dried gel particles of Ni/Al 2 O 3 and Al 2 O 3 provide quantitative information on pore structure, size distribution, and shape with 3D spatial resolution approaching 50 nm, while identical particles are imaged ex situ before and after calcination. The X‐ray imaging results are correlated with N 2 ‐sorption, Hg porosimetry and He pycnometry pore characterization. Hard X‐ray nanotomography is highlighted to derive fine structural details including tortuosity, branching nodes, and closed pores, which are relevant in understanding transport phenomena during chemical reactions. XRP and PXCT are enabling technologies to understand complex synthesis pathways of porous materials.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2RA01459A
Abstract: Schematic representation of ZrO 2 crystallites (a) monoclinic ZrO 2 , (b) tetragonal ZrO 2 following Si-stabilization, (c) mesoporous t-ZrO 2 following Si-stabilization and use of surfactant dodecylamine.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0SE00570C
Abstract: The ability of a polypyridyl cobalt( ii ) complex containing a redox-active tetradentate ligand to assist the electroreduction of CO 2 has been investigated in DMF.
Publisher: Wiley
Date: 09-03-2022
Abstract: There is considerable motivation in the catalysis community and chemical industry to envision a future where rational catalyst design and targeted chemical process optimization become standard. Achieving this goal for heterogeneous catalysis requires a cultural shift centered around effective research data management. The core elements of modern catalysis research are synthesis, characterization, and testing, while all can be elevated by effective collection, correlation, interoperation, and exploitation of data between disciplines and stakeholders. Here, first steps are made towards a holistic picture of an industrial Ni/Al 2 O 3 reference catalyst for CO 2 methanation. A range of conventional and advanced characterization tools are applied to probe metal particle size and pore characteristics of the support, selected as crucial parameters for catalyst performance. Challenges are shown with respect to current reporting of characterization data and metadata, which ultimately influences the development and reliability of digital twins in catalysis research. Furthermore, the cooperation and combined expertise of erse research groups from different fields is recognized as essential to deliver meaningful progress towards the digital future of catalysis research.
Publisher: Wiley
Date: 22-06-2022
Abstract: Cylindrical, cm‐sized monolithic Al 2 O 3 xerogels with hierarchical meso‐/macropore system were prepared by sol‐gel synthesis. The influence of both solvent exchange and drying on monolith stability and the resulting pore system was studied following mass and volume of the monolith as well as by porosimetry and electron microscopy. Crack‐free drying of the monoliths requires a proper management of drying stress. This is achieved by adjusting the drying rate and solvent exchange procedure applied to the intermediate lyogels. Moreover, mainly through differences in capillary pressure, changing the pore fluid allows an adjustment of the mesopore width from 7.6 nm to 10.5 nm. Neither solvent exchange nor drying affect the macropores, the width of which stays at 1.5 μm. Finally, CO 2 methanation over Ni‐impregnated Al 2 O 3 monoliths reveals CO 2 conversion and CH 4 selectivity comparable to an industrial Ni/Al 2 O 3 benchmark catalyst.
Publisher: MDPI AG
Date: 16-12-2020
Abstract: CO2 methanation is often performed on Ni/Al2O3 catalysts, which can suffer from mass transport limitations and, therefore, decreased efficiency. Here we show the application of a hierarchically porous Ni/Al2O3 catalyst for methanation of CO2. The material has a well-defined and connected meso- and macropore structure with a total porosity of 78%. The pore structure was thoroughly studied with conventional methods, i.e., N2 sorption, Hg porosimetry, and He pycnometry, and advanced imaging techniques, i.e., electron tomography and ptychographic X-ray computed tomography. Tomography can quantify the pore system in a manner that is not possible using conventional porosimetry. Macrokinetic simulations were performed based on the measures obtained by porosity analysis. These show the potential benefit of enhanced mass-transfer properties of the hierarchical pore system compared to a pure mesoporous catalyst at industrially relevant conditions. Besides the investigation of the pore system, the catalyst was studied by Rietveld refinement, diffuse reflectance ultraviolet-visible (DRUV/vis) spectroscopy, and H2-temperature programmed reduction (TPR), showing a high reduction temperature required for activation due to structural incorporation of Ni into the transition alumina. The reduced hierarchically porous Ni/Al2O3 catalyst is highly active in CO2 methanation, showing comparable conversion and selectivity for CH4 to an industrial reference catalyst.
No related grants have been discovered for Ken Luca Abel.