State‐of‐the‐Art<scp>X</scp>‐Ray Spectroscopy in Catalysis

Bokhoven, Jeroen A. van; Lamberti, Carlo

doi:10.1002/9783527699827.ch39

Cited by 6 publications

(4 citation statements)

References 109 publications

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“…The active sites are amenable to kinetic and spectroscopic characterization techniques, thereby providing opportunities for systematic investigation of the roles of the metal and the supporting ligand in the catalytic cycle. In this regard, advancement in spectroscopic techniques, such as solid-state dynamic nuclear polarization (DNP) nuclear magnetic resonance (NMR) − spectroscopy, X-ray absorption spectroscopy (XAS), − and periodic and cluster model calculations has played a pivotal role in the progress of SOMC. Recent advances in predictive modeling of various spectroscopic signatures in well-defined catalysts represents a synergy between these two areas and enables previously inaccessible molecular level characterization of the supported organometallic fragments. − Pioneering works from the groups of Marks, − Basset, − Copéret, − Gates, − Tilley, − Scott, − and others − have demonstrated effective tuning of the activity and selectivity of single-site catalysts through precursor engineering and control over support platforms, harnessing fundamental structural and mechanistic insights into catalytic species for chemical processes which include polymerization/oligomerization, metathesis, hydrogenolysis, hydrogenation, dehydrogenation, and hydroelementations (Si, B).…”

Section: Introductionmentioning

confidence: 99%

Nontraditional Catalyst Supports in Surface Organometallic Chemistry

et al. 2020

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The field of Surface Organometallic Chemistry (SOMC) aims to blend the positive attributes of homogeneous and heterogeneous catalysis. Significant insight into heterogeneous systems has been gained over the years through the synthesis, characterization, and application of well-defined surface organometallic catalysts, predominantly supported on silica and alumina. Considerable research efforts have focused on the application of homogeneous methods to the synthesis and characterization of these systems. Homogeneous catalysis has thrived on its ability to electronically and sterically tune ligands to yield desired reactivity and selectivity. Efforts in SOMC, however, have only recently turned to harnessing the stereoelectronic diversity of potential inorganic support materials beyond silica and alumina in order to exert similar control on the reactivity of the organometallic active site. The support material is intrinsically linked to electronic structure and reactivity of heterogeneous organometallic systems in the same way that ligands exert control over homogeneous catalyst systems. The ability to tune the reactivity of heterogeneous catalysts by changing the support is of great value, and it is anticipated that this will represent an area of significant growth in the field. In this Perspective, the use and future of nontraditional catalyst supports, such as sulfated metal oxides, modified silicas, and redox active supports are discussed.

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Section: Introductionmentioning

confidence: 99%

Nontraditional Catalyst Supports in Surface Organometallic Chemistry

et al. 2020

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“…These, in turn, are tuned by the local coordination environment of the Cu center. X-ray spectroscopy provides a valuable tool for investigating the geometric and electronic structure of catalytic transition-metal centers. − In particular, K-edge X-ray absorption spectroscopy (XAS) probes transitions from the metal 1s core orbital to unoccupied electronic states that depend both on the oxidation state of the metal center and the local coordination environment. , In the past years, high-energy resolution fluorescence detection XAS (HERFD-XAS) methods have been established − that remove the lifetime broadening and thus reveal additional spectral features, in particular, in the pre-edge region, which is due to transitions into chemically relevant low-lying unoccupied electronic states. , In combination with other spectroscopic methods as well as quantum-chemical calculations, XAS and HERFD-XAS have been successfully applied for investigating catalytic reaction mechanisms, for example, of SCR catalysis with Cu-doped zeolites. − …”

Section: Introductionmentioning

confidence: 99%

Revisiting the Dependence of Cu K-Edge X-ray Absorption Spectra on Oxidation State and Coordination Environment

Rudolph

Jacob

2018

Inorg. Chem.

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X-ray absorption spectroscopy (XAS) at the Cu K-edge is an important tool for probing the properties of copper centers in transition-metal chemistry and catalysis. However, the interpretation of experimental XAS spectra requires a detailed understanding of the dependence of spectroscopic features on the local geometric and electronic structure, which can be established by theoretical X-ray spectroscopy. Here, we present a systematic computational study of the Cu K-edge XAS spectra of selected Cu complexes based on time-dependent density-functional theory in combination with a molecular orbital analysis of the relevant transitions. For a series of Cu ammine model complexes as well as a comprehensive test set of 12 Cu(I) and 5 Cu(II) complexes, we revisit the dependence of the pre-edge region in Cu K-edge XAS spectra on oxidation state and coordination geometry. While our calculations confirm earlier experimental assignments, we can also reveal additional signatures of the ligand orbitals and identify the underlying orbital interactions. The comprehensive picture revealed by this study will provide a reliable basis for the interpretation of in situ Cu K-edge XAS spectra of catalytic intermediates.

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“…The method used is precipitation with HCl 5M. Aluminium shows rich variations in coordination depending on temperature, moisture content, and zeolite [6].…”

Section: Introductionmentioning

confidence: 99%

Zeolite Synthesis Based Silica from Saccharum officinarum L. with Black Stem Using the Hydrothermal Method

Redi,

Astuti,

Ramadhani

et al. 2024

J. Pijar.MIPA

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Saccharum officinarum L. has a high amount of silica content, which can be used as the main component of zeolite synthesis. Silica was isolated from Saccharum officinarum L. bagasse with NaOH and HCl. This research aims to synthesize zeolite using silica from Saccharum officinarum L. with black stem and alumina from aluminium foil. The Saccharum officinarum L. used in this research was sourced from Lombok Island, West Nusa Tenggara Province, Indonesia. Silica was sourced from Saccharum officinarum L. using the sol-gel method. The silica from the isolation of dregs ash obtained 20 g of silica with a high percentage (yield) of 50%. This study found that 5.29 g of aluminium foil produced 14.29 g of alumina with the addition of 22.50 g of Na2CO3. The zeolite obtained was 3.88 g with a SiO2:Al2O3 ratio of 5:3. From this study, the percent (%) of obtained zeolite was 48.5% from the weight of the silica and alumina produced. The zeolite results synthesized from Saccharum officinarum L. ash were characterized using FTIR. Based on the FTIR results, absorption was found at wave numbers (cm-1) 960, 729, and 668. The zeolite obtained was pure white and had a FTIR spectrum similar to that of Zeolite X from previous research. It can be predicted that the zeolite obtained from this research has been formed. This research is expected to be useful in increasing the effectiveness of the silica extraction process from Saccharum officinarum L. with black stem. Further analysis using XRD and SEM is needed to determine the characteristics of the zeolite produced.

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State‐of‐the‐ArtX‐Ray Spectroscopy in Catalysis

Cited by 6 publications

References 109 publications

Nontraditional Catalyst Supports in Surface Organometallic Chemistry

Nontraditional Catalyst Supports in Surface Organometallic Chemistry

Revisiting the Dependence of Cu K-Edge X-ray Absorption Spectra on Oxidation State and Coordination Environment

Zeolite Synthesis Based Silica from Saccharum officinarum L. with Black Stem Using the Hydrothermal Method

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