Thermally stable mesoporous tetragonal zirconia through surfactant-controlled synthesis and Si-stabilization

Thermally stable, highly mesoporous Si-stabilized ZrO₂ was prepared by sol–gel-synthesis. By utilizing the surfactant dodecylamine (DDA), large mesopores with a pore width of ∼9.4 nm are formed. Combined with an NH₃-treatment on the hydrogel, a high specific surface area of up to 225 m² g⁻¹ and pore volume up to 0.46 cm³ g⁻¹ are obtained after calcination at 973 K. The individual contributions of Si-addition, DDA surfactant and the NH₃-treatment on the resulting pore system were studied by inductively coupled plasma with optical emission spectrometry (ICP-OES), X-ray diffraction (XRD), N₂ sorption, and transmission electron microscopy (TEM). Electron tomography was applied to visualize and investigate the mesopore network in 3D space. While Si prevents the growth of ZrO₂ crystallites and stabilizes the t-ZrO₂ phase, DDA generates a homogeneous mesopore network within the zirconia. The NH₃-treatment unblocks inaccessible pores, thereby increasing specific surface area and pore volume while retaining the pore width distribution

Harte Röntgen‐Nanotomographie zur 3D‐Analyse der Verkokung in Nickel‐basierten Katalysatoren

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/Al2O3-Katalysatoren für die CO2-Methansierung und CH4-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

Hard X-Ray Nanotomography for 3D Analysis of Coking in Nickel-Based Catalysts

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/Al2O3 catalysts for CO2 methanation and CH4 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

Hard X‐ray Nanotomography for 3D Analysis of Coking in Nickel‐based Catalysts

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

Evolution of Hierarchically Porous Nickel Alumina Catalysts Studied by X‐Ray Ptychography

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) sample 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

Porosity and Structure of Hierarchically Porous Ni/Al₂O₃ Catalysts for CO₂ Methanation

CO$_{2}$ methanation is often performed on Ni/Al$_{2}$O$_{3}$ catalysts, which can suffer from mass transport limitations and, therefore, decreased efficiency. Here we show the application of a hierarchically porous Ni/Al$_{2}$O$_{2}$ catalyst for methanation of CO$_{2}$. 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., N$_{2}$ 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 H$_{2}$-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/Al$_{2}$O$_{3}$ catalyst is highly active in CO$_{2}$ methanation, showing comparable conversion and selectivity for CH$_{4}$ to an industrial reference catalyst

Digitization in Catalysis Research: Towards a Holistic Description of a Ni/Al2O3 Reference Catalyst for CO2 Methanation

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 diverse research groups from different fields is recognized as essential to deliver meaningful progress towards the digital future of catalysis research

Porosity and Structure of Hierarchically Porous Ni/Al₂O₃ Catalysts for CO₂ Methanation

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

Multiple novel prostate cancer susceptibility signals identified by fine-mapping of known risk loci among Europeans

Genome-wide association studies (GWAS) have identified numerous common prostate cancer (PrCa) susceptibility loci. We have fine-mapped 64 GWAS regions known at the conclusion of the iCOGS study using large-scale genotyping and imputation in 25 723 PrCa cases and 26 274 controls of European ancestry. We detected evidence for multiple independent signals at 16 regions, 12 of which contained additional newly identified significant associations. A single signal comprising a spectrum of correlated variation was observed at 39 regions; 35 of which are now described by a novel more significantly associated lead SNP, while the originally reported variant remained as the lead SNP only in 4 regions. We also confirmed two association signals in Europeans that had been previously reported only in East-Asian GWAS. Based on statistical evidence and linkage disequilibrium (LD) structure, we have curated and narrowed down the list of the most likely candidate causal variants for each region. Functional annotation using data from ENCODE filtered for PrCa cell lines and eQTL analysis demonstrated significant enrichment for overlap with bio-features within this set. By incorporating the novel risk variants identified here alongside the refined data for existing association signals, we estimate that these loci now explain ∼38.9% of the familial relative risk of PrCa, an 8.9% improvement over the previously reported GWAS tag SNPs. This suggests that a significant fraction of the heritability of PrCa may have been hidden during the discovery phase of GWAS, in particular due to the presence of multiple independent signals within the same regio