scholarly journals Identification of single Ru(II) ions on ceria as a highly active catalyst for abatement of NOx pollutants

2021 ◽  
Author(s):  
Konstantin Khivantsev ◽  
Nicholas R. Jaegers ◽  
Hristiyan A. Aleksandrov ◽  
Libor Kovarik ◽  
Inhak Song ◽  
...  
Keyword(s):  
Noble Metals ◽  
No Reduction ◽  
Supported Catalyst ◽  
No Oxidation ◽  
Single Atom ◽  
No Reduction By Co ◽  
Highly Active ◽  
Ceria Support ◽  
Potential Applicability

Atom trapping allows to prepare catalysts with atomically dispersed Ru ions anchored to the ceria support. The resulting catalysts free of expensive noble metals such as Pt, Pd, Rh (whose prices are ~8-60 times higher than Ru on the per-molar basis) with Ru loadings of only 0.25-0.5 wt% show excellent activity in industrially important catalytic NO oxidation reaction, a critical step that requires use of relatively large loadings of expensive noble metals in diesel aftertreatment systems. Ru1/CeO2 catalysts are stable during continuous cycling, ramping and cooling as well as presence of moisture. Furthermore, Ru1/CeO2 shows excellent NOx storage properties during cold start, with improved NO adsorption compared with the best described Pd/Zeolite NO adsorbers with ~2-3 times higher Pd loadings. We clarify the location of Ru(II) ions on the ceria surface and identify mechanism of NO oxidation (as well as reactive storage) using DFT calculations and in-situ DRIFTS/Mass-spectroscopy measurements. Furthermore, we show the possible applications of Ru1/CeO2 in gasoline engines for NO reduction by CO: only 0.1 wt% of atomically dispersed Ru is sufficient to achieve high activity at low temperatures. With the aid of excitation-modulation in-situ infra-red measurements, we uncover the elementary steps of NO reduction by CO on an atomically dispersed ceria-supported catalyst. Our study highlights the potential applicability of single-atom catalysts to industrially relevant NO and CO abatement.

scholarly journals A Cobalt-Iron Double-Atom Catalyst for the Oxygen Evolution Reaction

2019 ◽  
Author(s):  
Lichen Bai ◽  
Chia-Shuo Hsu ◽  
Duncan Alexander ◽  
Hao Ming Chen ◽  
Xile Hu
Keyword(s):  
Oxygen Evolution ◽  
Active Site ◽  
Oxygen Evolution Reaction ◽  
Active Sites ◽  
Single Atom ◽  
X Ray ◽  
Highly Active ◽  
Cobalt Iron ◽  
X Ray Absorption

Single atom catalysts exhibit well-defined active sites and potentially maximum atomic efficiency. However, they are unsuitable for reactions that benefit from bimetallic promotion such as the oxygen evolution reaction (OER) in alkaline medium. Here we show that a single atom Co precatalyst can be in-situ transformed into a Co-Fe double atom catalyst for OER. This catalyst exhibits one of the highest turnover frequencies among metal oxides. Electrochemical, microscopic, and spectroscopic data including those from operando X-ray absorption spectroscopy, reveal a dimeric Co-Fe moiety as the active site of the catalyst. This work demonstrates double-atom catalysis as a promising approach for the developed of defined and highly active OER catalysts.

scholarly journals Effect of Precious Metals on NO Reduction by CO in Oxidative Conditions

2020 ◽  
Vol 10 (9) ◽  
pp. 3042
Author(s):  
Joudia Akil ◽  
Stéphane Siffert ◽  
Pirault-Roy Laurence ◽  
Damien P. Debecker ◽  
François Devred ◽  
...  
Keyword(s):  
Noble Metals ◽  
No Reduction ◽  
Rapid Development ◽  
Precious Metals ◽  
Value Added ◽  
Pt Nanoparticles ◽  
Bet Surface Area ◽  
Hydrogen Chemisorption ◽  
Heterogeneous Catalytic ◽  
No Reduction By Co

Carbon dioxide has become an environmental challenge, where the emissions have reached higher level than can be handled. In this regard, conversion of CO2 to value-added chemicals and thus recycling of CO2 appear a viable option. Prior to valorization, CO2 must be purified. Among several opportunities, oxyfuel combustion is a process in rapid development. However, the gases resulting from this process contain some traces of impurities that can hinder the recovery of CO2 such as NO and CO. This work has, therefore, focused on the study of the NO-CO reaction in an oxidizing medium, using heterogeneous catalytic materials based on various supported noble metals. These materials were extensively characterized by a variety of methods including Brunauer–Emmett–Teller (BET) surface area measurements, hydrogen chemisorption, transmission electron microscopy (TEM) and H2 temperature programmed reduction (H2-TPR). The results obtained show that the catalytic behavior of M/Al2O3 catalysts in CO oxidation and NO reduction with CO in oxidative conditions depends mainly on the nature of the metal. The best result for both reactions is obtained with Pt/Al2O3 catalyst. The Pt nanoparticles in their metallic form (Pt°) as evidenced by TPR could explain the activity.

In Situ Characterization of Highly Dispersed, Ceria-Supported Fe Sites for NO Reduction by CO

2015 ◽  
Vol 119 (8) ◽  
pp. 4224-4234 ◽  
Author(s):  
Charles A. Roberts ◽  
Dario Prieto-Centurion ◽  
Yasutaka Nagai ◽  
Yusaku F. Nishimura ◽  
Ryan D. Desautels ◽  
...  
Keyword(s):  
No Reduction ◽  
In Situ Characterization ◽  
No Reduction By Co ◽  
Highly Dispersed ◽  
Fe Sites

scholarly journals A Cobalt-Iron Double-Atom Catalyst for the Oxygen Evolution Reaction

2019 ◽  
Author(s):  
Lichen Bai ◽  
Chia-Shuo Hsu ◽  
Duncan Alexander ◽  
Hao Ming Chen ◽  
Xile Hu
Keyword(s):  
Oxygen Evolution ◽  
Active Site ◽  
Oxygen Evolution Reaction ◽  
Active Sites ◽  
Single Atom ◽  
X Ray ◽  
Highly Active ◽  
Cobalt Iron ◽  
X Ray Absorption

Single atom catalysts exhibit well-defined active sites and potentially maximum atomic efficiency. However, they are unsuitable for reactions that benefit from bimetallic promotion such as the oxygen evolution reaction (OER) in alkaline medium. Here we show that a single atom Co precatalyst can be in-situ transformed into a Co-Fe double atom catalyst for OER. This catalyst exhibits one of the highest turnover frequencies among metal oxides. Electrochemical, microscopic, and spectroscopic data including those from operando X-ray absorption spectroscopy, reveal a dimeric Co-Fe moiety as the active site of the catalyst. This work demonstrates double-atom catalysis as a promising approach for the developed of defined and highly active OER catalysts.

scholarly journals A Cu–Pd single-atom alloy catalyst for highly efficient NO reduction

2019 ◽  
Vol 10 (36) ◽  
pp. 8292-8298 ◽  
Author(s):  
Feilong Xing ◽  
Jaewan Jeon ◽  
Takashi Toyao ◽  
Ken-ichi Shimizu ◽  
Shinya Furukawa
Keyword(s):  
Noble Metal ◽  
Low Temperatures ◽  
No Reduction ◽  
Single Atom ◽  
Minimum Amount ◽  
Highly Efficient ◽  
Highly Active ◽  
Alloy Catalyst ◽  
Single Atom Alloy

Highly active and selective NO reduction was achieved at low temperatures using a minimum amount of noble metal Pd.

NO reduction by CO over Pd/Ce0.6Zr0.4O2Al2O3 catalysts: in situ FT-IR studies of NO and CO adsorption

2002 ◽  
Vol 334 ◽  
pp. 318-326 ◽  
Author(s):  
R. Di Monte ◽  
J. Kaspar ◽  
P. Fornasiero ◽  
M. Graziani ◽  
C. Pazé ◽  
...  
Keyword(s):  
No Reduction ◽  
Co Adsorption ◽  
No Reduction By Co ◽  
Ir Studies ◽  
No And Co Adsorption ◽  
Ft Ir

scholarly journals Effect of Precious Metals on NO Reduction by CO in Oxidative Conditions

2020 ◽  
Author(s):  
Joudia Akil ◽  
Stephane Siffert ◽  
Pirault-Roy Laurence ◽  
Damien P. Debecker ◽  
François Devred ◽  
...  
Keyword(s):  
Noble Metals ◽  
No Reduction ◽  
Precious Metals ◽  
Value Added ◽  
Pt Nanoparticles ◽  
Bet Surface Area ◽  
Hydrogen Chemisorption ◽  
Global Challenge ◽  
No Reduction By Co ◽  
Temperature Programmed

Carbon dioxide has become a global challenge, where the emissions have become more than what could be handled. In this regard, conversion of CO2 to value added chemicals and thus recycling CO2 became a viable option. One of these options is the use of a process in strong development: oxycombustion. However, the gases resulting from this process contain some traces of impurities that can hinder the recovery of CO2 such as NO and CO. This work has therefore focused on the study of the reaction of NO reduction by CO in an oxidizing medium, using catalytic materials based on various supported noble metals. These materials were extensively characterized by a variety of methods including BET surface area measurements, hydrogen chemisorption, Transmission Electron Microscopy (TEM) and H2 temperature programmed reduction (H2-TPR). The obtained results show that the catalytic behaviour of M/Al2O3 catalysts in CO oxidation and NO reduction with CO in oxidative conditions depends mainly on the nature of the metal. The best result for these both reactions is obtained with Pt/Al2O3 catalyst. The Pt nanoparticles existing in the metallic form (Pt°) showed by TPR could explain the activity.

scholarly journals An ultrafast and facile nondestructive strategy to convert various inefficient commercial nanocarbons to highly active Fenton-like catalysts

2022 ◽  
Vol 119 (3) ◽  
pp. e2114138119
Author(s):  
Junhui Wang ◽  
Qi Fu ◽  
Jiaxing Yu ◽  
Huangsheng Yang ◽  
Zhengping Hao ◽  
...  
Keyword(s):  
Negative Charge ◽  
Single Atom ◽  
High Catalytic Activity ◽  
Metal Free ◽  
Highly Active ◽  
Activation Efficiency ◽  
Noncovalent Functionalization ◽  
Persulfate Activation ◽  
Harsh Conditions

The Fenton-like process catalyzed by metal-free materials presents one of the most promising strategies to deal with the ever-growing environmental pollution. However, to develop improved catalysts with adequate activity, complicated preparation/modification processes and harsh conditions are always needed. Herein, we proposed an ultrafast and facile strategy to convert various inefficient commercial nanocarbons into highly active catalysts by noncovalent functionalization with polyethylenimine (PEI). The modified catalysts could be in situ fabricated by direct addition of PEI aqueous solution into the nanocarbon suspensions within 30 s and without any tedious treatment. The unexpectedly high catalytic activity is even superior to that of the single-atom catalyst and could reach as high as 400 times higher than the pristine carbon material. Theoretical and experimental results reveal that PEI creates net negative charge via intermolecular charge transfer, rendering the catalyst higher persulfate activation efficiency.

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