Analysis of Preferred Mechanisms of CO Oxidation with Atomically Dispersed Pt1/TiO2 Using the Energetic Span Model

Mapping Intimacies ◽

10.26434/chemrxiv-2021-vsjnx ◽

2021 ◽

Author(s):

Selin Bac ◽

Shaama Mallikarjun Sharada

Keyword(s):

Low Temperature ◽

Co Oxidation ◽

Density Functional ◽

Co Adsorption ◽

Ab Initio Molecular Dynamics ◽

Functional Theory ◽

Support Materials ◽

Dispersed Catalysts ◽

Active Metal ◽

Low Temperature Co Oxidation

This work examines mechanisms of low-temperature CO oxidation over a single binding site of atomically dispersed Pt on rutile TiO2 (110) using density functional theory and the energetic span model (ESM). Of the 12 distinct pathways spanning Eley- Rideal (ER), termolecular ER (TER), Langmuir-Hinshelwood (LH), Mars-Van Krevelen (MvK) mechanisms as well as their combinations, TER with CO-assisted CO2 desorption yields the highest turnover frequency (TOF). However, this pathway is ruled out because Pt is dynamically unstable in an intermediate state in the TER cycle, determined in a prior ab initio molecular dynamics study by our group. We instead find, depending on reaction conditions, that either H1 is rendered inactive upon CO adsorption or the ER mechanism is preferred if O2 dissociatively adsorbs. ER exhibits the second highest TOF and the TOF-determining state is in qualitative agreement with experiment. TOFs for all MvK pathways are several orders of magnitude lower than ER and LH. By comparing TOFs for Pt1/TiO2 with prior mechanistic studies of various oxide-supported atomically dispersed catalysts in the literature, we identify the most active metal and support materials for low-temperature CO oxidation.

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Analysis of Preferred Mechanisms of CO Oxidation with Atomically Dispersed Pt1/TiO2 Using the Energetic Span Model

10.26434/chemrxiv-2021-v2x7j ◽

2021 ◽

Author(s):

Selin Bac ◽

Shaama Mallikarjun Sharada

Keyword(s):

Co Oxidation ◽

Density Functional ◽

Ab Initio Molecular Dynamics ◽

Turnover Frequency ◽

Mechanistic Studies ◽

Functional Theory ◽

Support Materials ◽

Dispersed Catalysts ◽

Co2 Desorption ◽

Low Temperature Co Oxidation

This work examines the mechanisms of low-temperature CO oxidation with atomically dispersed Pt on rutile TiO2 (110) using density functional theory and the energetic span model (ESM). Of the 13 distinct pathways spanning Eley-Rideal (ER), termolecular ER (TER), Langmuir-Hinshelwood(LH), Mars-Van Krevelen (MvK) mechanisms as well as their combinations, TER with CO-assisted CO2 desorption yields the highest turnover frequency (TOF). However, this pathway is ruled out because Pt is dynamically unstable in an intermediate state in the TER cycle, determined in a prior ab initio molecular dynamics study by our group. We instead find that a previously neglected pathway – the ER mechanism – is the most plausible CO oxidation route based on agreement with experimental TOFs and turnover-determining states. The preferred mechanism is sensitive to temperature, with LH becoming more favorable than ER and TER above 750 K. By comparing TOFs for Pt1/TiO2 with prior mechanistic studies of various oxide-supported atomically dispersed catalysts in the literature, we also attempt to identify the most viable metal and support materials for CO oxidation.

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Unique structure of active platinum-bismuth site for oxidation of carbon monoxide

Nature Communications ◽

10.1038/s41467-021-23696-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Bing Nan ◽

Qiang Fu ◽

Jing Yu ◽

Miao Shu ◽

Lu-Lu Zhou ◽

...

Keyword(s):

Carbon Monoxide ◽

Low Temperature ◽

Co Oxidation ◽

Density Functional ◽

Technology Development ◽

Co Adsorption ◽

Combustion Engines ◽

Advanced Combustion ◽

Surface Metal ◽

Bismuth Cluster

AbstractAs the technology development, the future advanced combustion engines must be designed to perform at a low temperature. Thus, it is a great challenge to synthesize high active and stable catalysts to resolve exhaust below 100 °C. Here, we report that bismuth as a dopant is added to form platinum-bismuth cluster on silica for CO oxidation. The highly reducible oxygen species provided by surface metal-oxide (M-O) interface could be activated by CO at low temperature (~50 °C) with a high CO2 production rate of 487 μmolCO2·gPt−1·s−1 at 110 °C. Experiment data combined with density functional calculation (DFT) results demonstrate that Pt cluster with surface Pt−O−Bi structure is the active site for CO oxidation via providing moderate CO adsorption and activating CO molecules with electron transformation between platinum atom and carbon monoxide. These findings provide a unique and general approach towards design of potential excellent performance catalysts for redox reaction.

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Novel structure of active platinum-bismuth site for oxidation of carbon monoxide

10.21203/rs.3.rs-123932/v1 ◽

2020 ◽

Author(s):

Bing Nan ◽

Qiang Fu ◽

Miao Shu ◽

Lulu Zhou ◽

Wei-Wei Wang ◽

...

Keyword(s):

Carbon Monoxide ◽

Low Temperature ◽

Co Oxidation ◽

Density Functional ◽

Technology Development ◽

Co Adsorption ◽

Advanced Combustion ◽

Novel Structure ◽

Surface Metal ◽

Bismuth Cluster

Abstract As the technology development, the future advanced combustion engines must be designed to perform at a low temperature. Thus, it is a great challenge to synthesize high active and stable catalysts to resolve exhaust below 100 °C. Here, we report that bismuth as a dopant added to form platinum-bismuth cluster on silica for CO oxidation. The highly reducible oxygen species provided by surface metal-oxide (M-O) interface could be activated by CO at low temperature (~ 50 °C) with a high CO2 production rate of 487 µmolCO2·gPt−1·s− 1 at 110 °C. Experiment data combined with density functional calculation (DFT) results demonstrate that Pt cluster with surface Pt−O−Bi structure is the active site for CO oxidation via providing moderate CO adsorption and activating CO molecules with electron transformation between platinum atom and carbon monoxide. These findings provide a novel and general approach towards design of potential outstanding performance catalysts for redox reaction.

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The role of zirconia in cobaltosic oxide catalysts for low-temperature CO oxidation

RSC Advances ◽

10.1039/c6ra23098a ◽

2016 ◽

Vol 6 (112) ◽

pp. 111070-111078 ◽

Cited By ~ 1

Author(s):

Fan Du ◽

Guisheng Wu ◽

Dongsen Mao ◽

Guanzhong Lu

Keyword(s):

Low Temperature ◽

Co Oxidation ◽

Co Adsorption ◽

Oxide Catalysts ◽

Low Temperature Co Oxidation ◽

Cobaltosic Oxide ◽

Adsorption Desorption

A series of Co3O4/ZrO2 catalysts for low-temperature CO oxidation was prepared, and then characterized by low-temperature N2 adsorption/desorption, XRD, TEM, XPS, UV-vis, CO-TPR, CO adsorption and CO2 desorption.

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The Origin of Au/Ce1-xZrxO2 Catalyst’s Active Sites in Low-Temperature CO Oxidation

Catalysts ◽

10.3390/catal10111312 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1312

Author(s):

Izabela Dobrosz-Gómez ◽

Miguel-Ángel Gómez-García ◽

Jacek Michał Rynkowski

Keyword(s):

Low Temperature ◽

Co Oxidation ◽

Active Sites ◽

Surface Composition ◽

Co Adsorption ◽

Gold Catalysis ◽

Support Surface ◽

Oxide Support ◽

Low Temperature Co Oxidation

Gold catalysts have found applications in many reactions of both industrial and environmental importance. Great interest has been paid to the development of new processes that reduce energy consumption and minimize pollution. Among these reactions, the catalytic oxidation of carbon monoxide (CO) is an important one, considering that a high concentration of CO in the atmosphere creates serious health and environmental problems. This paper examines the most important achievements and conclusions arising from the own authorship contributions concerning (2 wt. % Au)/Ce1−xZrxO2 catalyst’s active sites in low-temperature CO oxidation. The main findings of the present review are: (1) The effect of preparing conditions on Au crystallite size, highlighting some of the fundamental underpinnings of gold catalysis: the Au surface composition and the poisoning effect of residual chloride on the catalytic activity of (2 wt. % Au)/Ce1−xZrxO2 catalysts in CO oxidation; (2) The identification of ion clusters related to gold and their effect on catalyst’ surface composition; (3) The importance of physicochemical properties of oxide support (e.g., its particle size, oxygen mobility at low temperature and redox properties) in the creation of catalytic performance of Au catalysts; (4) The importance of oxygen vacancies, on the support surface, as the centers for oxygen molecule activation in CO reaction; (5) The role of moisture (200–1000 ppm) in the generation of enhanced CO conversion; (6) The Au-assisted Mars-van Krevelen (MvK) adsorption–reaction model was pertinent to describe CO oxidation mechanism. The principal role of Au in CO oxidation over (2 wt. % Au)/Ce1−xZrxO2 catalysts was related to the promotion in the transformation process of reversibly adsorbed or inactive surface oxygen into irreversibly adsorbed active species; (7) Combination of metallic gold (Au0) and Au-OH species was proposed as active sites for CO adsorption. These findings can help in the optimization of Au-containing catalysts.

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