Untitled

Choi, Yeongsoo; Futagami, Katsuya; Fujitani, Tadahiro; Nakamura, Junji

doi:10.1023/a:1009074219286

Cited by 59 publications

(45 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This promoting effect found in the present study is not consistent with the findings in the previous studies [2,3], which reported that the specific activity of the Cu surface for the reverse water-gas shift reaction was not affected by Zn deposited on the Cu surface. The present finding suggests that ZnO particles adjacent to Cu particles could play some role in promoting the activity of the catalyst for the reverse water-gas shift reaction, and also that both increasing the Cu surface area of the catalyst and adding ZnO to a Cu-based catalyst should be important for developing a high performance catalyst for the reverse watergas shift reaction.…”

Section: Effects Of Zno Contained In Cu-based Catalysts On Their Acticontrasting

confidence: 99%

“…This promoting effect found in the present study is consistent with the findings in the previous studies on methanol synthesis from CO 2 /H 2 over Cu surface modified with Zn [2,3], which suggested that ZnO added to a Cu-based catalyst could produce active sites which have higher specific activities for methanol synthesis. However, the present results are not consistent with the results in the previous study on methanol synthesis from a feed-gas mixture containing around 10% of CO and of CO 2 over various Cu-based catalysts [4], which reported that their specific activities were almost the same.…”

Section: Effects Of Zno Contained In Cu-based Catalysts On Their Actisupporting

confidence: 93%

See 1 more Smart Citation

Development of high performance Cu/ZnO-based catalysts for methanol synthesis and the water-gas shift reaction

2004

View full text Add to dashboard Cite

Our group's studies on Cu/ZnO-based catalysts for methanol synthesis via hydrogenation of CO 2 and for the water-gas shift reaction are reviewed. Effects of ZnO contained in supported Cu-based catalysts on their activities for several reactions were investigated. The addition of ZnO to Cu-based catalyst supported on Al 2 O 3 , ZrO 2 or SiO 2 improved its specific activity for methanol synthesis and the reverse water-gas shift reaction, but did not improve its specific activity for methanol steam reforming and the water-gas shift reaction. Methanol synthesis from CO 2 and H 2 over Cu/ZnO-based catalysts was extensively studied under a joint research project between National Institute for Resources and Environment (NIRE; one of the former research institutes reorganized to AIST) and Research Institute of Innovative Technology for the Earth (RITE). It was suggested that methanol should be produced via the hydrogenation of CO 2 , but not via the hydrogenation of CO, and that H 2 O produced along with methanol should greatly suppress methanol synthesis. The Cu/ZnO-based multicomponent catalysts such as were highly active for methanol synthesis from CO 2 and H 2 . The addition of a small amount of colloidal silica to the multicomponent catalysts greatly improved their long-term stability during methanol synthesis from CO 2 and H 2 . The purity of the crude methanol produced in a bench plant was 99.9 wt% and higher than that of the crude methanol from a commercial methanol synthesis from syngas. The water-gas shift reaction over Cu/ZnO-based catalysts was also studied. The activity of Cu/ZnO/ZrO 2 /Al 2 O 3 catalyst for the water-gas shift reaction at 523 K was less affected by the pre-treatments such as calcination and treatment in H 2 at high temperatures than that of the Cu/ZnO/Al 2 O 3 catalyst. Accordingly, the Cu/ZnO/ZrO 2 / Al 2 O 3 catalyst was considered to be more suitable for practical use for the water-gas shift reaction. The Cu/ZnO/ZrO 2 /Al 2 O 3 catalyst was also highly active for the water-gas shift reaction at 673 K. Furthermore, a two-stage reaction system composed of the first reaction zone for the water-gas shift reaction at 673 K and the second reaction zone for the reaction at 523 K was found to be more efficient than a one-stage reaction system. The addition of a small amount of colloidal silica to a Cu/ZnO-based catalyst greatly improved its long-term stability in the water-gas shift reaction in a similar manner as in methanol synthesis from CO 2 and H 2 .

show abstract

Section: Effects Of Zno Contained In Cu-based Catalysts On Their Acticontrasting

confidence: 99%

Section: Effects Of Zno Contained In Cu-based Catalysts On Their Actisupporting

confidence: 93%

Development of high performance Cu/ZnO-based catalysts for methanol synthesis and the water-gas shift reaction

2004

View full text Add to dashboard Cite

show abstract

“…(ii) A Cu-Zn alloy forms upon calcinations of the catalyst and this alloy is the active phase for methanol synthesis [8][9][10][11][12]. (iii) Metallic Cu-clusters are the active species [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Growth of Copper on Single Crystalline ZnO: Surface Study of a Model Catalyst

2005

View full text Add to dashboard Cite

Copper, vapor-deposited on the polar, Zn-terminated ZnO(0001) surface is investigated in view of its suitability as model system for the technologically important Cu/ZnO catalyst. The structure and electronic properties of Cu clusters on ZnO(0001)-Zn have been studied with scanning tunneling microscopy (STM), low energy electron diffraction (LEED), ultraviolet photoelectron spectroscopy (UPS), and low-energy He + ion scattering (LEIS). At room temperature copper grows as two-dimensional (2D) clusters only at very low coverages of 0.001-0.05 equivalent monolayers (ML). At coverages greater than 0.01 ML, 3D clusters start to develop. This is contrasted to Cu growth on the oxygen-terminated ZnO(0001bar) surface, where a strong adhesion between Cu and the ZnO substrate results in an initial wetting of the surface by Cu. On ZnO(0001)-Zn, surface roughness and sputter damage change the growth mode to more 2D-like. Annealing in UHV results in well-separated, hexagonal clusters rotationally aligned with the substrate. Annealing of 2-5 ML Cu deposits on the ZnO(0001)-Zn surface in 10 )6 mbar O 2 results in the formation of a (Ö3 · Ö3)R30°superstructure with respect to the ZnO lattice. This superstructure likely contains Cu + sites. The suitability of the different surface morphologies to probe specific sites that are thought to be active for catalytic processes is discussed.

show abstract

“…Embora existam vários estudos teóricos 3-10 e experimentais [11][12][13][14][15][16][17][18][19][20][21][22][23] envolvendo ZnO as faces polares apresentam, comparativamente, um volume de estudos muito maior que faces apolares e, devido a isso, a superfície apolar foi escolhida para análise no presente estudo.…”

Section: Introductionunclassified

Theoretical Study of Modeling Parameters for the Non-Polar Zinc Oxide Surface

Lima¹,

Martins²

2016

Revista Virtual De Química

View full text Add to dashboard Cite

Abstract:Modeling in solid state involves the analysis of a varied number of parameters in order to determine if the proposed model is in accordance with experimental and theoretical results. In general, cut-off energy and k points are used as parameters yielding results that are comparable to experimental data. These data, as shown in this work, should be carefully studied before proceeding to more advanced stages of modeling. In this work we analyzed the cut-off energy, the number of k-points used and their influence on the geometry of solid zinc oxide. The cut-off energy and its relation to a more precise model were also discussed.Keywords: Zinc oxide; modeling; cut-off energy. ResumoA modelagem de sólidos envolve a análise de diversos fatores, para determinar se o modelo em questão está ou não de acordo com os dados obtidos experimentalmente, assim como com demais dados teóricos. De modo geral, valores como a energia de corte e número de pontos k são parâmetros que geram resultados comparáveis aos obtidos experimentalmente. Esses valores, conforme mostrado neste trabalho, devem ser bem avaliados antes de se prosseguir para estágios mais avançados de modelagem. Neste artigo, foram analisados a energia de corte, os pontos k e sua influência em fatores geométricos do óxido de zinco. Também é discutida a energia de superfície, bem como a sua relação com um modelo mais acurado.Palavras-chave: Óxido de zinco; modelagem; energia de corte.

show abstract

Untitled

Cited by 59 publications

References 29 publications

Development of high performance Cu/ZnO-based catalysts for methanol synthesis and the water-gas shift reaction

Development of high performance Cu/ZnO-based catalysts for methanol synthesis and the water-gas shift reaction

Growth of Copper on Single Crystalline ZnO: Surface Study of a Model Catalyst

Theoretical Study of Modeling Parameters for the Non-Polar Zinc Oxide Surface

Contact Info

Product

Resources

About