Microcalorimetric, infrared spectroscopic and DFT studies of CO adsorption on Rh and Rh–Te catalysts

He, Rong; Kusaka, Haruhiko; Mavrikakis, Manos; Dumesic, James A.

doi:10.1016/s0021-9517(03)00020-4

Cited by 5 publications

(6 citation statements)

References 33 publications

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“…He et al 79 The latter is supported by the experimental study by Jansen et al 66 The results obtained with the mechanism of Vincent et al, 18 coupled with the gas phase chemistry of Lindstedt and Skevis, 56 are shown in Figs. 2 and 4.…”

mentioning

confidence: 63%

“…The value depends on the coverage 78 and the geometry of the adsorbed species. 77 A higher initial value of 160 kJ/mol at very low coverages was proposed by He et al 79 The latter is supported by the experimental study by Jansen et al 66 that reports a heat of adsorption of 160 kJ/mol and barrier to desorption of 132 kJ/mol. An UBI−QEP calculation using Q 0̷ C = 350 kJ/mol produces a consistent value of Q CO = 166 kJ/ mol.…”

Section: Comments On Heats Of Adsorptionmentioning

confidence: 73%

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Microkinetic Mechanisms for Partial Oxidation of Methane over Platinum and Rhodium

Kraus

Lindstedt

2017

J. Phys. Chem. C

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A systematic approach for the development of heterogeneous mechanisms is applied and evaluated for the catalytic partial oxidation of methane over platinum (Pt) and rhodium (Rh). The derived mechanisms are self-consistent and based on a reaction class-based framework comprising variational transition state theory (VTST) and two-dimensional collision theory for the calculation of pre-exponential factors with barrier heights obtained using the unity bond index-quadratic exponential potential (UBI-QEP) method. The surface chemistry is combined with a detailed chemistry for the gas phase and the accuracy of the approach is evaluated over Pt for a wide range of stoichiometries (0.3 ≤ φ ≤ 4.0), pressures (2 ≤ P (bar) ≤ 16) and residence times. It is shown that the derived mechanism can reproduce experimental data with an accuracy comparable to the prevalent collision theory approach and without the reliance on experimental data for sticking coefficients. The derived mechanism for Rh shows encouraging agreement for a similar set of conditions and the robustness of the approach is further evaluated by incorporating partial updates via more accurate DFT determined barrier heights. Substantial differences are noted for some channels (e.g. where reaction progress is strongly influenced by early transition states) though the impact on the overall agreement with experimental data is moderate for the current systems. Remaining discrepancies are explored using sensitivity analyses to establish key parameters. The study suggests that the overall framework is well-suited for the efficient generation of heterogeneous reaction mechanisms, that it can serve to identify key parameters where high accuracy ab initio methods are required and that it permits the inclusion of such updates as part of a gradual refinement process.

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mentioning

confidence: 63%

Section: Comments On Heats Of Adsorptionmentioning

confidence: 73%

Microkinetic Mechanisms for Partial Oxidation of Methane over Platinum and Rhodium

Kraus

Lindstedt

2017

J. Phys. Chem. C

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“…Given the importance of maintaining thermodynamic consistency, Jim outlined a general strategy to parametrize the kinetic model. , Pre-exponential factors in rate constants are usually calculated from collision theory or transition state theory. Activation energies are estimated from experimental data, but when reliable data are not available, they are estimated from theoretical calculations or by using empirical correlations based on chemical similarities between elemental surface reactions. ,− With the remarkable development of computational chemistry, Jim actively promoted the use of DFT to determine the structure, stability, and reactivity of adsorbed species and also Monte Carlo (MC) simulations to study nonuniformity effects on the catalyst surface. ,,,− ,− ,,− More recently, a multiscale approach models the essential surface chemistry combining DFT calculations and MC simulations to get further insight about kinetically significant steps. − However, MKA was developed before these computational tools were available, and Jim suggested that the interest to learn deeper details of surface chemistry by using more sophisticated theoretical methods must be balanced by the practical need to solve complex challenges faced by society.…”

Section: Microkinetic Analysismentioning

confidence: 99%

A Career in Catalysis: James A. Dumesic

et al. 2021

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After 43 years as a professor in the Chemical and Biological Engineering Department at the University of Wisconsin-Madison, James A. Dumesic retired in 2019. Jim is one of the most influential researchers in the field of heterogeneous catalysis. In this Account, we discuss the scientific discoveries that he made and the intellectual processes that he followed during his illustrious career to steer the field of heterogeneous catalysis into new frontiers. He began his career by fundamentally probing the nature of active sites on heterogeneous catalysts using in situ Mossbauer spectroscopy, electron microscopy, FTIR, and kinetic analysis. This tool kit was used to elucidate the "strong metal support interaction" (SMSI) effect. He developed new microcalorimetric tools to measure the energetics of adsorbates on catalyst surfaces. Jim pioneered microkinetic analysis as a tool to describe heterogeneous reaction kinetics incorporating the essential surface chemistry into kinetic analysis, thereby providing a novel strategy for kinetic assisted catalyst design. Density functional theory (DFT) was combined with FTIR and microcalorimetry to elucidate catalytic surface reactions which were then incorporated into microkinetic models. In the early 2000s, Jim developed the aqueous-phase catalytic processing of biomass-derived oxygenates into fuels and chemicals. This led to the development of new processes to make diesel fuel, jet fuel, gasoline, aromatics, and oxygenated chemicals from renewable resources, several of these technologies are in the process of being commercialized. Jim tailored nanostructured catalytic materials by atomic layer deposition and controlled surface reactions to withstand harsh aqueous-phase biomass processing conditions. He used careful selection and tuning of the solvent composition to achieve substantial control over the activity and selectivity of various biomass upgrading reactions and developed a theory to explain these solvent effects. Underlying these discoveries was a thought process that used fundamental surface chemistry to explain the relationship between the structure, properties, and performance of the catalytic system. Leveraging this thought process across many different reaction classes helped to establish both new tools for catalysis research and to develop new processes for the sustainable production of fuels and chemicals.

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“…[28][29][30][31] We have calculated the surface energies of the low index (111), (110), and (100) surfaces that are considered to be the basic structures of Rh particles; the surface energy of the Rh(hkl) surface in vacuum is dened as follows: 32,33…”

Section: Surface Modelmentioning

confidence: 99%

“…For metal Rh, the (111) surface is the most abundant surface 27 and has been widely employed to investigate the reaction mechanisms of C 2 oxygenate formation 15,16 as well as the adsorption of diverse atoms and molecules. [28][29][30][31] We have calculated the surface energies of the low index (111), (110), and (100) surfaces that are considered to be the basic structures of Rh particles; the surface energy of the Rh(hkl) surface in vacuum is dened as follows: 32,33…”

Section: Surface Modelmentioning

confidence: 99%

Source and major species of CH_x(x = 1–3) in acetic acid synthesis from methane–syngas on Rh catalyst: a theoretical study

et al. 2014

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Density functional calculations have been carried out to investigate the source and major species of CH x (x ¼ 1-3) involved in acetic acid synthesis from methane-syngas on the Rh(111) surface. All possible formation pathways of CH x (x ¼ 1-3) from methane and syngas have been systematically investigated. For CH x formation from methane, our results show that CH is the most abundant species; for CH x formation from syngas, all CH x (x ¼ 1-3) species form from CHO by CO hydrogenation, and the optimal formation routes of CH x show that CH and CH 3 are the most abundant species rather than CH 2 and CH 3 OH. On the other hand, CH formed by methane is more favourable than CH and CH 3 formed by syngas; meanwhile, CO insertion into CH x species to form C 2 oxygenates as acetic acid precursors is more favourable than CO hydrogenation to CH and CH 3 . As a result, in acetic acid synthesis from methanesyngas, CH x (x ¼ 1-3) species come from methane rather than syngas, and the corresponding primary species is CH. In addition, the CO in syngas is predominantly responsible for insertion reactions that produce CHCO, which is a C 2 oxygenate precursor leading to the formation of acetic acid. Furthermore, microkinetic modelling analysis shows that the major product of acetic acid synthesis from methanesyngas on the Rh(111) surface is CH 3 COOH, and that the production of CH 3 OH cannot compete with that of CH 3 COOH.

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Microcalorimetric, infrared spectroscopic and DFT studies of CO adsorption on Rh and Rh–Te catalysts

Cited by 5 publications

References 33 publications

Microkinetic Mechanisms for Partial Oxidation of Methane over Platinum and Rhodium

Microkinetic Mechanisms for Partial Oxidation of Methane over Platinum and Rhodium

A Career in Catalysis: James A. Dumesic

Source and major species of CH_x(x = 1–3) in acetic acid synthesis from methane–syngas on Rh catalyst: a theoretical study

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Microcalorimetric, infrared spectroscopic and DFT studies of CO adsorption on Rh and Rh–Te catalysts

Cited by 5 publications

References 33 publications

Microkinetic Mechanisms for Partial Oxidation of Methane over Platinum and Rhodium

Microkinetic Mechanisms for Partial Oxidation of Methane over Platinum and Rhodium

A Career in Catalysis: James A. Dumesic

Source and major species of CHx(x = 1–3) in acetic acid synthesis from methane–syngas on Rh catalyst: a theoretical study

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Product

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Source and major species of CH_x(x = 1–3) in acetic acid synthesis from methane–syngas on Rh catalyst: a theoretical study