Methane oxidation activity and nanoscale characterization of Pd/CeO2 catalysts prepared by dry milling Pd acetate and ceria
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99 GENERAL AND MISCELLANEOUS↗
SEARCH · Engineering Papers
Results for “catalyst characterization”
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Calorimetric metal vapor adsorption energies for characterizing industrial catalyst support materials
Many important catalysts and electro-catalysts for energy and environmental technologies involve late transition metal atoms and nanoparticles dispersed across the surface of high-surface-area support materials, for example, oxide nanoparticles. The surface reactivity and long-term stability against deactivation of these materials depends strongly on the strength of bonding of the metal atom and nanoparticles to the support surface. Here, we introduce a novel calorimetry method that implements a LiTaO 3 crystal for heat detection and extends metal adsorption calorimetry to surfaces of nanomaterials that are deposited from liquid solutions, as is typical when preparing industrial catalyst supports. This allows one to measure the strength of metal atom bonding and the adhesion energy of metal nanoparticles to clean surfaces of technologically relevant catalyst supports. We demonstrate that here by measuring the heat of Ag vapor adsorption onto the clean surfaces of high-surface-area TiO 2 anatase powdered support materials (i.e., 5-nm-diameter nanoparticles). These heats of adsorption show a pulse-to-pulse standard deviation of only 9.3 kJ/mol (3.3%) for pulses containing only 1% of a monolayer of Ag vapor, with potential for a 5-fold reduction in noise if used with another metal evaporator. The calorimeter was also proven to work well measuring heats of Ag adsorption on calcium niobate(001) nanosheets deposited as thin films from liquid solution. Here, this calorimeter opens up the possibility of using metal adsorption calorimetry to screen catalyst support materials for the strengths with which they bind metal atoms and metal nanoparticles, offering new opportunities to discover better support materials or for basic scientific study of structure / function relationships with respect to metal / support bond energies.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Latent Representation Learning for Structural Characterization of Catalysts
Supervised machine learning-enabled mapping of the X-ray absorption near edge structure (XANES) spectra to local structural descriptors offers new methods for understanding the structure and function of working nanocatalysts. We briefly summarize a status of XANES analysis approaches by supervised machine learning methods. We present an example of an autoencoder-based, unsupervised machine learning approach for latent representation learning of XANES spectra. This new approach produces a lower-dimensional latent representation, which retains a spectrum–structure relationship that can be eventually mapped to physicochemical properties. Furthermore, the latent space of the autoencoder also provides a pathway to interpret the information content “hidden” in the X-ray absorption coefficient. Our approach (that we named latent space analysis of spectra, or LSAS) is demonstrated for the supported Pd nanoparticle catalyst studied during the formation of Pd hydride. By employing the low-dimensional representation of Pd K-edge XANES, the LSAS method was able to isolate the key factors responsible for the observed spectral changes.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Synchrotron Catalysis Consortium (SCC) at NSLS-II: Dedicated Beamline Facilities for In Situ and Operando Characterization of Catalysts
The Synchrotron Catalysis Consortium (SCC) was funded and established in September 2005 at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory (BNL). For more than a decade, the SCC was the first of its kind in the United States, with a mission to promote the utilization of synchrotron techniques for cutting-edge catalysis research under in-situ conditions. The consortium consists of three Principal Investigators (Jingguang Chen, Columbia University, Anatoly Frenkel, Stony Brook University/BNL, and Jose Rodriguez, BNL) and scientific staff member Nebojsa Marinkovic. The initial team also included Radoslav Adzic, BNL, and collaborators from academic, national, and industrial laboratories. During the first decade of its operations at three NSLS beamlines (X18A, X18B, and X19A) until the closing of NSLS on September 30, 2014, the primary goal of the SCC team was to provide assistance and to develop new sciences/techniques to the catalysis community...This report outlines a brief history, specifications, techniques, and training and outreach for the facility.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Replication Data for: Latent Representation Learning for Structural Characterization of Catalysts
The data underlying this published work have been made publicly available in this repository as part of the IMASC Data Management Plan. This work was supported as part of the Integrated Mesoscale Architectures for Sustainable Catalysis (IMASC), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0012573.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Latent Representation Learning for Structural Characterization of Catalysts
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99 GENERAL AND MISCELLANEOUS↗
Structural Evolution and Stability of Rh/TiO 2 Catalysts under CO 2 Hydrogenation Conditions: Influence of the Initial Rh Structure
Characterizing catalyst stability by identifying the predominant mechanisms, timescales and driving forces of catalyst reconstruction under relevant reaction conditions is necessary for the design and commercialization of new catalysts. Here, in this paper, we study Rh/TiO 2 catalysts under CO 2 hydrogenation conditions (773 K, 75% H 2 , 25% CO 2 ) at high conversion and utilize reactivity studies along with ex-situ and in-situ spectroscopy and microscopy to characterize changes in catalyst activity and structure as a function of time on stream and the initial catalyst structure. This is a prototypical catalyst for CO 2 hydrogenation where Rh structure and Rh-TiO 2 interactions have been proposed to explain reactivity, selectivity (between CO and CH 4 formation) and catalyst stability. The influence of the initial Rh structure (varying from Rh single atoms to Rh nanoparticles), support stability, regeneration and pretreatment(s), and the chemical potential(s) of the reaction environment on reaction selectivity and catalyst stability were explored. The product selectivity between CO and CH 4 was determined to be dependent on the relative fraction of Rh single atoms and Rh nanoparticle-TiO 2 interfacial sites under reaction conditions, each exhibiting distinct stability under prolonged time on stream. Surprisingly, Rh single atoms exhibited stability for the duration of 90 h reactivity measurements, even at high Rh density (≥ 1.8 Rh atoms/nm 2 ) on the support, while Rh nanoparticles sintered under reaction conditions. As a result, all catalysts exhibited increasing selectivity to CO with increasing time on stream (> 10 h). We conclude the distribution of Rh structures evolved over time under reaction conditions through three distinct reconstruction mechanisms (Rh particle fragmentation, Ostwald ripening, and particle migration and coalescence) that occurred on varying timescales. Catalyst stability on the ~90 h time scale was ultimately controlled by the initial Rh structure.
25 ENERGY STORAGE↗
Nanoscale crystallographic characterization of nanoporous catalyst by TKD
To better understand the structure-reactivity relationships of self-supported nanoporous catalysts, a nanoscale characterization of the materials is required. Transmission Kikuchi Diffraction (TKD), or transmission electron backscatter diffraction (t-EBSD), is a recent technique used to analyze the grain crystallography and morphology of thin films and nanometer-scale materials. Using a conventional EBSD detector in a FIB-SEM instrument, we investigate nanoporous gold (npAu) samples with ligament size in the 50-70 nm range. Grains with diameters below 50 nm can be clearly resolved, but also welldefined grain boundaries extending over 3 to 4 pixels, proving the high resolution of the method. The presence of contaminations during sample preparation by FIB milling is also discussed. We conclude the results provide deeper insight than conventional EBSD technique can alone.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Highly active Ni/CeO2 catalyst for CO2 methanation: Preparation and characterization
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99 GENERAL AND MISCELLANEOUS↗
Operando X-ray absorption spectroscopic investigation of electrocatalysts state in anion exchange membrane fuel cells
Capturing the active state of (electro)catalysts under operating conditions, namely operando, is the ultimate objective of (electro)catalyst characterization, enabling the unraveling of reaction mechanisms and advancing (electro)catalyst development. Operando insights advance our understanding of the correlations between electrochemical tests and device-level performances. However, operando characterization of electrocatalysts is challenging due to the complexity of electrochemical devices and instrumental limitations. As a result, the majority of electrocatalyst characterizations have been limited to half-cell in situ studies. Here, we present an operando X-ray absorption spectroscopic study of Mn spinel oxide electrocatalysts in an operating fuel cell employing a custom-designed cell. Our results reveal that in anion exchange membrane fuel cells, the Mn valence state, within spinel Mn 3 O 4 /C, increases to above 3+, adopting an octahedral coordination devoid of Jahn-Teller distortions. This structural change results in an AEMFC performance equivalent to that of Co 1.5 Mn 1.5 O 4 /C, a composition that outperforms Mn 3 O 4 /C in rotating disk electrode tests. Our results underscore the importance of operando characterizations in elucidating the active state of electrocatalysts and understanding the correlation(s) between electrochemical tests and device performance.
Electrocatalysis↗
Surface-supported cluster catalysis: Ensembles of metastable states run the show
It has recently been demonstrated that the dynamic behaviour of surface-supported nanocluster catalysts in realistic reaction conditions defies conventional models used in catalysis. This opens new doors in catalysis by giving more leverage in catalyst design, but also requires a major revision of the understanding of how dynamic heterogeneous catalytic interfaces operate, as well as of the computational approaches of catalyst modelling, and experimental methods of catalyst characterization. Key aspects of the new paradigm include the collective action of many catalyst states that form a statistical ensemble in reacting conditions, the catalytic activity and selectivity being driven by rare and metastable catalyst states, reaction thermodynamics and kinetics being controlled by different states of the catalyst, broken scaling relationships, non-Arrhenius behaviours, and catalyst dynamic restructuring being an essential part of the reaction mechanism. For computation, this complexity means the departure from the standard DFT calculations of reaction mechanisms on a single catalyst structure. For experiment, it calls for the development of operando characterization tools with the per-site resolution and the ability to find the minority sites that govern the catalytic activity. For catalyst design, the goal becomes the creation of the catalyst state (geometric and electronic) that might not be present in the as-prepared catalyst, but would develop in the reaction conditions and would have the desired activity then. While cluster catalysts are the most dramatic in their dynamic fluxionality, other amorphous interfaces also exhibit some of it, and thus are also subject to similar paradigm revision.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
BETO 2021 Peer Review - Advanced Catalyst Synthesis and Characterization (ACSC) Project WBS 2.5.4.304; 303; 305
The Advanced Catalyst Synthesis and Characterization (ACSC) project, in close collaboration with the Chemical Catalysis for Bioenergy (ChemCatBio) Consortium enabling projects, CatCost, and the Engineering of Catalyst Scale-Up project, (1) provides fundamental insight into working catalysts leading to actionable recommendations for all of the ChemCatBio catalysis projects, (2) addresses overarching catalysis challenges central to the ChemCatBio Consortium, and (3) adapts and applies new synthesis methodologies and in situ/operando characterization capabilities to meet the evolving needs of the catalysis projects. The outcome is a transition from empirical catalyst development to rational design through the prediction of materials with targeted properties based on advanced characterization combined with computational modeling, and the synthesis of next generation catalysts with predicted structures that yield demonstrated improvements in catalytic performance. In FY18, the ACSC helped to demonstrate the utility of the complete catalyst and process development cycle for dimethyl ether to high-octane gasoline over metal-modified zeolite catalysts for the Upgrading of C1 Building Blocks project, and in FY21 will leverage capabilities, expertise, and computational models established for this effort to target next-generation catalysts for ethanol to distillates for the Upgrading of C2 Intermediates project with enhanced performance in half the time.
29 ENERGY PLANNING, POLICY, AND ECONOMY↗
Mesoporous Fe-doped MgO nanoparticles as a heterogeneous photo-Fenton-like catalyst for degradation of salicylic acid in wastewater
Mesoporous Fe-doped MgO nanoparticles were synthesized using a facile sol-gel method and utilized for photo-Fenton-like degradation of salicylic acid (SA). The MgO surface dissolution facilitated an increase in the pH under the reaction conditions that allowed the Fe-MgO catalyst to be active without detectable iron leaching. Under simulated solar radiation, SA was completely degraded with an initial rate constant of 0.048 min -1 at the optimal reaction conditions of 500 ppm loading of 5% Fe-MgO, 20 mM H 2 O 2 concentration, and 50 ppm SA concentration. The catalyst was stable over 5 reaction cycles. The Fe-MgO catalyst was shown to have a surface area up to 171 m 2 /g and contain hematite (Fe 2 O 3 ) nanoparticles with octahedrally coordinated iron catalytic centers, as inferred from diffuse reflectance UV–vis measurements. Post-reaction catalyst characterization showed that some Fe 2+ was present in the catalyst due to the redox cycle during the chain initiation and propagation steps of the reaction.
36 MATERIALS SCIENCE↗
NREL'S Capabilities in Catalyst Development and Characterization
The Thermal and Catalytic Process Development Unit at NREL has state-of-the-art equipment for thermochemical process development and testing, ranging from catalyst and feedstock characterizations to bench-scale reactors to pilot plants. Within this facility is the capability to understand structure-performance relationships for advanced catalytic materials to enable improved carbon yield and reduced costs for the targeted conversion of renewable feedstocks. This fact sheet summarizes the core capabilities and applications.
09 BIOMASS FUELS↗
Atomically Dispersed Supported Metal Catalysts: Understanding Fundamentals and Extending to New Catalyst Classes
We report synthesis, characterization, and catalyst performance data for supported metal catalysts, primarily those consisting of noble metals on metal oxide and zeolite supports.
36 MATERIALS SCIENCE↗
Production of Gaseous Olefins from Syngas over a Cobalt-HZSM-5 Catalyst
Light olefins (C2–C5) are high-value platform chemicals used to produce plastics, lubricants, coating material, and surfactants, and can be intermediates to produce transportation fuels. In this study we report on the development of a Co-based catalyst for direct conversion of fossil as well as biomass derived syngas into light olefins that enables high conversion and olefin/paraffin (O/P) product ratio, minimal selectivity to CO2 (<?1%) and wax formation (C14+ selectivity?<?1%). Over a Co/HZSM-5 bi-functional catalyst 38% CO conversion with C2–C5 olefin selectivity of 48%, and O/P ratio of 4.0 was achieved at 240 °C, 17 bar, and 1.5 L/(g–h). In addition to a gaseous olefin-rich stream a C6–C13 mixed olefin/paraffin liquid byproduct was also produced with 25% selectivity. Both Co loading and the HZSM-5 acidity levels were optimized to maintain the balance between the hydrogenation and the cracking activity to generate high levels of C2–C4 olefins. A suite of catalyst characterization tools were used to correlate the physical and chemical property of the catalyst to the performance of the catalyst towards syngas conversion and C2–C4 olefin selectivity.
Maddi, Balakrishna↗
Microwave-Assisted Syngas Cleanup: Catalytic Reforming of Gasifier Tar Using a Low-Cost Iron Catalyst
In this work, we studied the microwave-assisted catalytic dry reforming of toluene using Fe/Al2O3 as a catalyst, under CO2 at different reaction temperatures. The toluene reforming reaction was conducted using microwave and conventional thermal reactors. The results showed that under microwave irradiation, a higher CO2 and toluene conversions, as well as better hydrogen yield can be observed compared to conventional toluene reforming at the same reaction temperature. The catalyst stability test was also investigated. Three reaction pathways were observed during microwave reaction: the toluene decomposition produces initial hydrogen and carbon deposit on the catalyst; the formation of methane and benzene suggests toluene hydrodemethylation that took place secondly; toluene hydrogenolysis forms light alkanes such as methane, and through reforming reaction under CO2 to syngas. The pre- and post-reaction catalyst characterizations were done to reveal the structure-reactivity relationships and compare the catalyst structure after microwave and conventional reactions.
Bai, Xinwei↗
Multiphysics and Multiscale Simulation Methods for Electromagnetic Energy Assisted Fossil Fuel to Hydrogen Conversion (Final Scientific/Technical Report)
This report summarizes the technical accomplishments of the four-year research project “Multiphysics and Multiscale Simulation Methods for Electromagnetic Energy Assisted Fossil Fuel to Hydrogen Conversion” (Award No. DE-FE0032092), conducted at Howard University and the University of Houston (subawardee) from September 2021 to August 2025. The project successfully achieved all four major objectives: 1. 3D Structural Characterization – Developed 3D optical imaging and mechanical sectioning methods to characterize catalyst distribution and support morphology in nickel foam substrates. Successfully reconstructed 3D geometries and imported them into COMSOL Multiphysics for electromagnetic simulations. 2. EM Hotspot Simulation – Created all-frequency stable electromagnetic formulations and 3D nodal discontinuous Galerkin (NDG) methods for coupled electromagnetic-thermal-fluid problems in multiscale catalytic media. Demonstrated stable solutions from DC to microwave frequencies. 3. Multiphysics Coupling – Developed multiscale simulation methods coupling FEM electromagnetic solvers with thermal transport equations. Reactive molecular dynamics (ReaxFF MD) simulations were performed to investigate catalytic reaction mechanisms at the atomistic level. Demonstrated electromagnetic-thermal co-simulation capabilities for porous catalyst structures. 4. System Optimization – Designed and optimized EM-assisted catalytic systems using nickel foam and carbon foam structures, demonstrating significant temperature increases due to microwave heating. Observed and characterized plasma generation in carbon fiber catalysts. Investigated multiple reaction chamber geometries for improved microwave energy deposition. The project produced significant scientific contributions including 15+ peer-reviewed publications, trained multiple Ph.D. students and undergraduate researchers, and advanced the understanding of microwave-assisted hydrogen production from fossil fuels.
08 HYDROGEN↗