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1.
[Pt12(CO)24]2–/NaY and [Pt9(CO)18]2–/NaY exhibited much higher activities in the CO+NO reaction at 473 K compared with Pt/Al2O3. Kinetic study andin-situ FTIR results suggest that NO adsorption is the rate-limiting step in the CO+NO reaction on intrazeolite Pt carbonyl clusters. 相似文献
2.
In order to improve the CO catalytic oxidation performance of a Pt/TiO2 catalyst, a series of Pt/TiO2 catalysts were prepared via an impregnation method in this study, and various characterization methods were used to explore the effect of TiO2 calcination pretreatment on the CO catalytic oxidation performance of the catalysts. The results revealed that Pt/TiO2 (700 °C) prepared by TiO2 after calcination pretreatment at 700 °C exhibits a superior CO oxidation activity at low temperatures. After calcination pretreatment, the catalyst exhibited a suitable specific surface area and pore structure, which is beneficial to the diffusion of reactants and reaction products. At the same time, the proportion of adsorbed oxygen on the catalyst surface was increased, which promoted the oxidation of CO. After calcination pretreatment, the adsorption capacity of the catalyst for CO and CO2 decreased, which was beneficial for the simultaneous inhibition of the CO self-poisoning of Pt sites. In addition, the Pt species exhibited a higher degree of dispersion and a smaller particle size, thereby increasing the CO oxidation activity of the Pt/TiO2 (700 °C) catalyst. 相似文献
3.
High‐Performance Ru1/CeO2 Single‐Atom Catalyst for CO Oxidation: A Computational Exploration
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Fengyu Li Lei Li Prof. Xinying Liu Prof. Xiao Cheng Zeng Prof. Zhongfang Chen 《Chemphyschem》2016,17(20):3170-3175
By means of density functional theory computations, we examine the stability and CO oxidation activity of single Ru on CeO2(111), TiO2(110) and Al2O3(001) surfaces. The heterogeneous system Ru1/CeO2 has very high stability, as indicated by the strong binding energies and high diffusion barriers of a single Ru atom on the ceria support, while the Ru atom is rather mobile on TiO2(110) and Al2O3(001) surfaces and tends to form clusters, excluding these systems from having a high efficiency per Ru atom. The Ru1/CeO2 exhibits good catalytic activity for CO oxidation via the Langmuir–Hinshelwood mechanism, thus is a promising single‐atom catalyst. 相似文献
4.
Supported metallic catalysts were prepared from pyrolysis of the organometallic clusters RuOs3(CO)13(μ-H)2, Os3(CO)10(μ-AuPPh3)2, Os3(CO)12, Ru3(CO)12 and [Ru(CO)4]n, on either silica or titania, and their catalytic performance for CO oxidation has been assessed against a supported catalyst prepared from RuCl3. Ruthenium catalysts prepared from organometallic precursors were found to exhibit better activity, and that supported on TiO2 exhibited activity at the lowest operating temperature. 相似文献
5.
Herein, we report on the synthesis of ultrasmall Pd nanoclusters (∼2 nm) protected by L-cysteine [HOCOCH(NH2)CH2SH] ligands (Pdn(L-Cys)m) and supported on the surfaces of CeO2, TiO2, Fe3O4, and ZnO nanoparticles for CO catalytic oxidation. The Pdn(L-Cys)m nanoclusters supported on the reducible metal oxides CeO2, TiO2 and Fe3O4 exhibit a remarkable catalytic activity towards CO oxidation, significantly higher than the reported Pd nanoparticle catalysts. The high catalytic activity of the ligand-protected clusters Pdn(L-Cys)m is observed on the three reducible oxides where 100 % CO conversion occurs at 93–110 °C. The high activity is attributed to the ligand-protected Pd nanoclusters where the L-cysteine ligands aid in achieving monodispersity of the Pd clusters by limiting the cluster size to the active sub-2-nm region and decreasing the tendency of the clusters for agglomeration. In the case of the ceria support, a complete removal of the L-cysteine ligands results in connected agglomerated Pd clusters which are less reactive than the ligand-protected clusters. However, for the TiO2 and Fe3O4 supports, complete removal of the ligands from the Pdn(L-Cys)m clusters leads to a slight decrease in activity where the T100% CO conversion occurs at 99 °C and 107 °C, respectively. The high porosity of the TiO2 and Fe3O4 supports appears to aid in efficient encapsulation of the bare Pdn nanoclusters within the mesoporous pores of the support. 相似文献
6.
Man Zhou Muhong Li Chujun Hou Zhongyu Li Yongzheng Wang Kun Xiang Xuefeng Guo 《中国化学快报》2018,29(6):787-790
Pt nanocrystallines (~3 nm) covered with controllable carbon layers were synthesized by photochemical reduction method which exhibited extraordinary anti-sintering properties and different CO oxidation activities. 相似文献
7.
Fangyuan Cheng Jie Zhang Prof. Kui Xie 《Angewandte Chemie (International ed. in English)》2023,62(12):e202300480
Introducing pores in single crystals creates a new type of porous materials that incorporate porosity and structural coherence. Herein, we use in situ transmission electron microscopy to disclose the porosity formation by converting KTiOPO4 (KTP) single crystals into porous single-crystalline (PSC) TiO2 monoliths in a solid-solid transformation. The isolated crystalline nuclei of TiO2 clusters with identical lattice orientation on KTP surface moves TiO2/KTP interface toward mother phase for growing PSC TiO2 monoliths. The relative density in PSC TiO2 monoliths dominates porosity while the macroscopic dimensions remain unchanged in the transformation. The single-crystalline nature of porous architecture stabilizes oxygen vacancy to activate lattice oxygen while the three-dimensional percolation enhances species diffusion. PSC TiO2 monoliths with deposited Pt clusters show enhanced and stable catalytic CO oxidation in air at ∼75 °C for 200 hours of operation. 相似文献
8.
采用密度泛函理论探讨了 TiO2 表面负载 Co2B2 和 Co2B2Pt 合金簇可能的负载构型. 结果表明, Co2B2 和 Co2B2Pt 合金簇倾向于以两个 Co 的形式负载在两个氧上. 态密度分析发现, 负载后, Co2B2 合金簇中部分 Co 原子和 B 原子成键加强, Co2B2Pt 合金簇中 Pt 原子和 B 原子成键也加强, 形成新的轨道. CO 和 O2 在 Co2B2/TiO2 和 Co2B2Pt/TiO2 表面吸附的结果表明, Co2B2Pt/TiO2 催化氧化 CO 性能的提高是由于 Pt 原子提高了 Co2B2 合金簇吸附 CO 和 O2 的能力. 相似文献
9.
Jifei Jia Liwu Lin Jianyi Shen Zhusheng Xu Tao Zhang Dongbai Liang Yi Chen 《中国科学B辑(英文版)》1998,41(6):606-615
CO adsorption microcalorimetry was employed in the study of γ-Al2O3-supported Pt, Pt-Sn and Pt-Fe catalysts. The results indicated that the initial differential heat of CO adsorption of the
Pt/γ-Al2O3 catalyst was 125 kJ/mol. As CO coverage increased, the differential heat of adsorption decreased. At higher coverages, the
differential heat of adsorption decreased significantly. 60% of the differential heat of CO adsorption on the Pt/γ-N2O3 catalyst was higher than 100 kJ/mol. No significant effect on the initial differential heat was found after adding Sn and
Fe to the Pt/γ-Al2O3 catalyst. The amount of strong CO adsorption sites decreased, while the portion of CO adsorption sites with differential
heat of 60–110 kJ/mol increased after increasing the Sn or Fe content. This indicates that the surface adsorption energy was
changed by adding Sn or Fe to Pt/γ-N2O3. The distribution of differential heat of CO adsorption on the Pt-Sn(C)/γ-Al2O3 catalyst was broad and homogeneous. Comparison of the dehydrogenation performance of C4 alkanes with the number of CO adsorption sites with differential heat of 60–110 kJ/mol showed a good correlation. These results
indicate that the surface Pt centers with differential heats of 60–110 kJ/mol for CO adsorption possess superior activity
for the dehydrogenation of alkanes.
Project supported by FORD and the National Natural Science Foundation of China (Grant No. 09412302) and the Transcentury Training
Program Foundation for the Talents by The State Education Commission of China. 相似文献
10.
Pt(111)表面上一氧化碳的吸附与氧化反应1)刘金尧(清华大学一碳化工国家重点实验室北京100084)XuMZaeraF(DepartmentofChemistryUniversityofCaliforniaRiversideCA92521)关键词... 相似文献
11.
In view of the high activity of Pt single atoms in the low-temperature oxidation of CO, we investigate the adsorption behavior of Pt single atoms on reduced rutile TiO\begin{document}$ _2 $\end{document} (110) surface and their interaction with CO and O\begin{document}$ _2 $\end{document} molecules using scanning tunneling microscopy and density function theory calculations. Pt single atoms were prepared on the TiO\begin{document}$ _2 $\end{document} (110) surface at 80 K, showing their preferred adsorption sites at the oxygen vacancies. We characterized the adsorption configurations of CO and O\begin{document}$ _2 $\end{document} molecules separately to the TiO\begin{document}$ _2 $\end{document} -supported Pt single atom samples at 80 K. It is found that the Pt single atoms tend to capture one CO to form Pt-CO complexes, with the CO molecule bonding to the fivefold coordinated Ti (Ti\begin{document}$ _{5 \rm{c}} $\end{document} ) atom at the next nearest neighbor site. After annealing the sample from 80 K to 100 K, CO molecules may diffuse, forming another type of complexes, Pt-(CO)\begin{document}$ _2 $\end{document} . For O\begin{document}$ _2 $\end{document} adsorption, each Pt single atom may also capture one O\begin{document}$ _2 $\end{document} molecule, forming Pt-O\begin{document}$ _2 $\end{document} complexes with O\begin{document}$ _2 $\end{document} molecule bonding to either the nearest or the next nearest neighboring Ti\begin{document}$ _{5 \rm{c}} $\end{document} sites. Our study provides the single-molecule-level knowledge of the interaction of CO and O\begin{document}$ _2 $\end{document} with Pt single atoms, which represent the important initial states of the reaction between CO and O\begin{document}$ _2 $\end{document} . 相似文献
12.
Infrared spectra of CO-treated platinum hydrosols subsequently treated with acetylene, hydrogen, and oxygen reveal that v(CO)ads decreases from 2070 cm−1 with increasing gas-treatment time. This has been attributed to a reduction in the coverage of adsorbed CO. In Pt sol/CO/C2H2 systems, v(CO)ads decreases to a limiting value of ca. 2060 cm−1 after exposure to acetylene. In the Pt sol/CO/H2 systems, v(CO)ads decreases to ca. 2050 cm−1 after exposure to hydrogen gas. The lower frequency in the Pt sol/CO/H2 system has been attributed to CO adsorption on more active metal sites formed from the reduction of surface platinum oxides. Exposure of the CO-treated platinum hydrosols to O2 gas was found to cause the eventual disappearance of the v(CO)ads band in infrared spectra, which was attributed to oxidation of adsorbed CO to CO2 by weakly bound surface layers of platinum oxides formed by the oxygen treatment. 相似文献
13.
Dr. Zhaoyu Wang Lijuan Huang Bo Su Junli Xu Prof. Zhengxin Ding Dr. Sibo Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(2):517-523
This work reports the preparation of a La2O3-modified Pt/TiO2 (Pt/La-TiO2) hybrid through an excess-solution impregnation method and its application for CO2 hydrogenation catalysis. The Pt/La-TiO2 catalyst is characterized by XRD, H2 temperature-programmed reduction (TPR), TEM, X-ray photoelectron spectroscopy (XPS), Raman, EPR, and N2 sorption measurements. The Pt/La-TiO2 composite starts to catalyze the CO2 conversion reaction at 220 °C, which is 30 °C lower than the Pt/TiO2 catalyst. The generation of CH4 and CO of Pt/La-TiO2 is 1.6 and 1.4 times greater than that of Pt/TiO2. The CO2 temperature-programmed desorption (TPD) analysis confirms the strengthened CO2 adsorption on Pt/La-TiO2. Moreover, the in situ FTIR experiments demonstrate that the enhanced CO2 adsorption of Pt/La-TiO2 facilitates the formation of the active Pt–CO intermediate and subsequently boosts the evolution of CH4 and CO. The cycling tests reveal that Pt/La-TiO2 shows reinforced stability for the CO2 hydrogenation reaction because the La species can prevent Pt nanoparticles (NPs) from sintering. This work may provide some guidance on the development new rare-metal-modified hybrid catalysts for CO2 fixation. 相似文献
14.
R. C. Binning Meng‐Sheng Liao Carlos R. Cabrera Yasuyuki Ishikawa Hakim Iddir Renxuan Liu E. S. Smotkin Antonio J. Aldykiewicz Deborah J. Myers 《International journal of quantum chemistry》2000,77(2):589-598
B3LYP and SCF‐Xα calculations have been performed on PtnRu(10−n)CO (n = 6–10) clusters. The work aims to simulate the adsorption of CO on the (111) surface of platinum metal and to examine the electronic effects that arise when some Pt atoms are replaced with Ru. Adsorption energies and Pt C and C O stretching frequencies have been calculated for each cluster. Ru does affect the electronic structure of the clusters, the calculated adsorption energies, and frequencies, the Pt C frequency more than the C O. The donation‐backbonding mechanism that accompanies the shift in CO stretching frequency that occurs when CO adsorbs on platinum does not explain the differences in frequency shift observed in CO on various Pt/Ru surfaces. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 77: 589–598, 2000 相似文献
15.
Dong Gun Oh Prof. Hristiyan A. Aleksandrov Haneul Kim Dr. Iskra Z. Koleva Dr. Konstantin Khivantsev Prof. Georgi N. Vayssilov Prof. Ja Hun Kwak 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(49):e202200684
Pd-based catalysts are the most widely used for CO oxidation because of their outstanding catalytic activity and thermal stability. However, fundamental understanding of the detailed catalytic processes occurring on Pd-based catalysts under realistic conditions is still lacking. In this study, we investigated CO oxidation on metallic Pd clusters supported on Al2O3 and SiO2. High-angle annular dark-field scanning transmission electron microscopy revealed the formation of similar-sized Pd clusters on Al2O3 and SiO2. In contrast, CO chemisorption analysis indicated a gradual change in the dispersion of Pd (from 0.79 to 0.2) on Pd/Al2O3 and a marginal change in the dispersion (from 0.4 to 0.24) on Pd/SiO2 as the Pd loading increased from 0.27 to 5.5 wt %; these changes were attributed to differences in the metal-support interactions. Diffuse reflectance infrared Fourier-transform spectroscopy revealed that fewer a-top CO species were present in Pd supported on Al2O3 than those in Pd supported on SiO2, which is related to the morphological differences in the metallic Pd clusters on these two supports. Despite the different dispersion profiles and surface characteristics of Pd, O2 titration demonstrated that linearly bound CO (with an infrared signal at 2090 cm−1) reacted first with oxygen in the case of CO-saturated Pd on Al2O3 and SiO2, which suggests that a-top CO on the terrace site plays an important role in CO oxidation. The experimental observations were corroborated by periodic density functional calculations, which confirmed that CO oxidation on the (111) terrace sites is most plausible, both kinetically and thermodynamically, compared to that on the edge or corner sites. This study will deepen the fundamental understanding of the effect of Pd clusters on CO oxidation under reaction conditions. 相似文献
16.
Bimetallic Ag‐Pt Sub‐nanometer Supported Clusters as Highly Efficient and Robust Oxidation Catalysts
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Dr. Fabio R. Negreiros Dr. Avik Halder Dr. Chunrong Yin Dr. Akansha Singh Dr. Giovanni Barcaro Dr. Luca Sementa Dr. Eric C. Tyo Dr. Michael J. Pellin Dr. Stephan Bartling Dr. Karl‐Heinz Meiwes‐Broer Dr. Sönke Seifert Dr. Prasenjit Sen Dr. Sandeep Nigam Dr. Chiranjib Majumder Dr. Nobuyuki Fukui Dr. Hisato Yasumatsu Dr. Stefan Vajda Dr. Alessandro Fortunelli 《Angewandte Chemie (International ed. in English)》2018,57(5):1209-1213
A combined experimental and theoretical investigation of Ag‐Pt sub‐nanometer clusters as heterogeneous catalysts in the CO→CO2 reaction (COox) is presented. Ag9Pt2 and Ag9Pt3 clusters are size‐selected in the gas phase, deposited on an ultrathin amorphous alumina support, and tested as catalysts experimentally under realistic conditions and by first‐principles simulations at realistic coverage. In situ GISAXS/TPRx demonstrates that the clusters do not sinter or deactivate even after prolonged exposure to reactants at high temperature, and present comparable, extremely high COox catalytic efficiency. Such high activity and stability are ascribed to a synergic role of Ag and Pt in ultranano‐aggregates, in which Pt anchors the clusters to the support and binds and activates two CO molecules, while Ag binds and activates O2, and Ag/Pt surface proximity disfavors poisoning by CO or oxidized species. 相似文献
17.
根据一氧化氮(NO)气体在二氧化钛(TiO2)表面吸附和脱附的实验结果, 揭示了气体脱附量的变化规律. 利用MOPAC 和GAUSSIAN分子轨道理论计算了在TiO2(110)表面上吸附NO分子的原子簇模型, 电荷分布以及原子簇的能级, 推断了NO在TiO2(110)表面吸附的稳定性. 相似文献
18.
N. U. Zhanpeisov 《Kinetics and Catalysis》2010,51(6):849-853
The present theoretical DFT study discusses the structure and chemical activity of transition metal and metal oxide catalysts
within the well-known cluster approach. Selective oxidation of carbon monoxide on gold supported on titania (Au/TiO2 (110)) as well as some key points in understanding the effect of non-metal doping on TiO2 with the aim to increase its photocatalytic
functionality have been briefly discussed. It was shown that Au (with formal oxidation state equal to plus one) stabilized
on water-assisted and vacancy containing TiO2 (110) can explain selective oxidation of CO. Here binding of O2 with the vacancy site is energetically preferable than its adsorption on an Au site. Conversely, CO adsorbs on an Au center
of Au/TiO2 (110) which is energetically much more profitable than its interaction with the oxygen vacancy site. Also, carbon and nitrogen
doping on TiO2 (110) leads to two different structures. Energetically most profitable is that carbon occupies an interstitial position in
deep bulk while nitrogen replaces the protruded oxygen atom and forms a surface N-H group. 相似文献
19.
20.
Catalytically Active Rh Sub‐Nanoclusters on TiO2 for CO Oxidation at Cryogenic Temperatures
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Hongling Guan Dr. Jian Lin Dr. Botao Qiao Dr. Xiaofeng Yang Dr. Lin Li Dr. Shu Miao Prof. Jingyue Liu Prof. Aiqin Wang Prof. Xiaodong Wang Prof. Tao Zhang 《Angewandte Chemie (International ed. in English)》2016,55(8):2820-2824
The discovery that gold catalysts could be active for CO oxidation at cryogenic temperatures has ignited much excitement in nanocatalysis. Whether the alternative Pt group metal (PGM) catalysts can exhibit such high performance is an interesting research issue. So far, no PGM catalyst shows activity for CO oxidation at cryogenic temperatures. In this work, we report a sub‐nano Rh/TiO2 catalyst that can completely convert CO at 223 K. This catalyst exhibits at least three orders of magnitude higher turnover frequency (TOF) than the best Rh‐based catalysts and comparable to the well‐known Au/TiO2 for CO oxidation. The specific size range of 0.4–0.8 nm Rh clusters is critical to the facile activation of O2 over the Rh–TiO2 interface in a form of Rh?O?O?Ti (superoxide). This superoxide is ready to react with the CO adsorbed on TiO2 sites at cryogenic temperatures. 相似文献