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Title: Copper cluster size effect in methanol synthesis from CO 2

Abstract

Here, size-selected Cu n catalysts ( n = 3, 4, 20) were synthesized on Al 2O 3 thin films using mass-selected cluster deposition. A systematic study of size and support effects was carried out for CO 2 hydrogenation at atmospheric pressure using a combination of in situ grazing incidence X-ray absorption spectroscopy, catalytic activity measurement, and first-principles calculations. The catalytic activity for methanol synthesis is found to strongly vary as a function of the cluster size; the Cu 4/Al 2O 3 catalyst shows the highest turnover rate for CH 3OH production. With only one atom less than Cu 4, Cu 3 showed less than 50% activity. Density functional theory calculations predict that the activities of the gas-phase Cu clusters increase as the cluster size decreases; however, the stronger charge transfer interaction with Al 2O 3 support for Cu 3 than for Cu 4 leads to remarkably reduced binding strength between the adsorbed intermediates and supported Cu 3, which subsequently results in a less favorable energetic pathway to transform carbon dioxide to methanol.

Authors:
 [1];  [1];  [1];  [1]; ORCiD logo [1];  [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Argonne National Lab. (ANL), Lemont, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1372481
Grant/Contract Number:
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 121; Journal Issue: 19; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Yang, Bing, Liu, Cong, Halder, Avik, Tyo, Eric C., Martinson, Alex B. F., Seifert, Sonke, Zapol, Peter, Curtiss, Larry A., and Vajda, Stefan. Copper cluster size effect in methanol synthesis from CO2. United States: N. p., 2017. Web. doi:10.1021/acs.jpcc.7b01835.
Yang, Bing, Liu, Cong, Halder, Avik, Tyo, Eric C., Martinson, Alex B. F., Seifert, Sonke, Zapol, Peter, Curtiss, Larry A., & Vajda, Stefan. Copper cluster size effect in methanol synthesis from CO2. United States. doi:10.1021/acs.jpcc.7b01835.
Yang, Bing, Liu, Cong, Halder, Avik, Tyo, Eric C., Martinson, Alex B. F., Seifert, Sonke, Zapol, Peter, Curtiss, Larry A., and Vajda, Stefan. 2017. "Copper cluster size effect in methanol synthesis from CO2". United States. doi:10.1021/acs.jpcc.7b01835.
@article{osti_1372481,
title = {Copper cluster size effect in methanol synthesis from CO2},
author = {Yang, Bing and Liu, Cong and Halder, Avik and Tyo, Eric C. and Martinson, Alex B. F. and Seifert, Sonke and Zapol, Peter and Curtiss, Larry A. and Vajda, Stefan},
abstractNote = {Here, size-selected Cun catalysts (n = 3, 4, 20) were synthesized on Al2O3 thin films using mass-selected cluster deposition. A systematic study of size and support effects was carried out for CO2 hydrogenation at atmospheric pressure using a combination of in situ grazing incidence X-ray absorption spectroscopy, catalytic activity measurement, and first-principles calculations. The catalytic activity for methanol synthesis is found to strongly vary as a function of the cluster size; the Cu4/Al2O3 catalyst shows the highest turnover rate for CH3OH production. With only one atom less than Cu4, Cu3 showed less than 50% activity. Density functional theory calculations predict that the activities of the gas-phase Cu clusters increase as the cluster size decreases; however, the stronger charge transfer interaction with Al2O3 support for Cu3 than for Cu4 leads to remarkably reduced binding strength between the adsorbed intermediates and supported Cu3, which subsequently results in a less favorable energetic pathway to transform carbon dioxide to methanol.},
doi = {10.1021/acs.jpcc.7b01835},
journal = {Journal of Physical Chemistry. C},
number = 19,
volume = 121,
place = {United States},
year = 2017,
month = 5
}

Journal Article:
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  • The effect of the reaction medium (CO + H{sub 2}, CO{sub 2} + H{sub 2}, and CO + CO{sub 2} + H{sub 2}) on the surface composition and valent state of copper at the surface of a commercial copper-zinc-aluminum catalyst SNM-1 for methanol synthesis is studied by XPS for the first time. Upon catalyst reduction in hydrogen, its surface is found to contain only Cu(0). On catalyst exposure to the CO{sub 2} + H{sub 2} mixture, Cu(0), Cu(I), and Cu(II) are shown to coexist at the surface. After treating the catalyst with the CO + H{sub 2} mixture, copper ismore » present in the Cu(0) state, and the addition of CO{sub 2} does not change the valent state of copper. It is concluded that the active sites of the catalysts for methanol synthesis may be Cu(0) and Cu(I). It is shown that the Zn/Cu atomic concentration ratio depends on the gas medium composition. The action of the He + 2% O{sub 2} oxidizing mixture on the reduced catalyst enhances the surface content of copper several times.« less
  • It is shown that in the initial period of catalyst operation at 210 to 220/sup 0/C the rate of methanol formation is independent of the granule size. With an increase in temperature, the effect of internal diffusion retardation becomes stronger and the rate of methanol formation decreases with an increase in the granule size. For catalyst samples which have partially lost activity, the rate of methanol formation at low temperatures is higher on large tablets than on fine granules. At temperatures above 240/sup 0/C the relationship of the rates changes: the rate of methanol formation on large tablets is lessmore » than on fine ones. It is suggested that it is expedient to replace tablets with larger granules at certain points in the reaction zone of an adiabatic shaft reactor. 4 references, 4 figures.« less
  • This article presents the results obtained in a study of the effect of the sulfur compounds found in the starting gas on the low-temperature copper containing SNM-1 catalyst, which is used industrially for synthesis of methanol at a pressure of 5MPa. Experimental results indicate that the rate of absorption of sulfur by an SNM-1 catalyst is proportional to the outside surface of the granules. If catalysts of different granule sizes are poisoned with the same amount of sulfur, the catalyst of the larger granule size has the advantage. Within the investigated limits (sulfur concentration in catalyst to 0.09%), no correlationmore » was found between the specific surface of copper and the activity of the catalyst.« less
  • This paper presents an investigation of the promotional effect of potassium on unsupported copper catalysts for the hydrogenation of carbon monoxide. Using X-ray photoelectron spectroscopy (XPS), the authors determined that under reaction conditions copper exists as a mixture of Cu{sup +} and Cu{sup 0} species. Metallic copper by itself is inactive for the hydrogenation of carbon monoxide, while the authors have found that the addition of potassium to copper forms an active and selective (up to 98 wt %) methanol synthesis catalyst. The initiation of catalytic activity correlated with the stabilization of the Cu{sup +} species. The potassium promoter wasmore » determined to be in the form of the thermodynamically stable carbonate. Potassium promotes this catalyst by stabilizing the Cu{sup +} species, probably in the form of CuKCO{sub 3}.« less
  • Catalytic CO{sub 2} hydrogenation to methanol has received considerable attention as an effective way to utilize CO{sub 2}. In this paper, density functional theory was employed to investigate the methanol synthesis from CO{sub 2} and H{sub 2} on a Mo{sub 6}S{sub 8} cluster. The Mo{sub 6}S{sub 8} cluster is the structural building block of the Chevrel phase of molybdenum sulfide, and has a cagelike structure with an octahedral Mo{sub 6} metallic core. Our calculations indicate that the preferred catalytic pathway for methanol synthesis on the Mo{sub 6}S{sub 8} cluster is very different from that of bulklike MoS{sub 2}. MoS{sub 2}more » promotes the C-O scission of H{sub x}CO intermediates, and therefore, only hydrocarbons are produced. The lower S/Mo ratio for the cluster compared to stoichiometric MoS{sub 2} might be expected to lead to higher activity because more low-coordinated Mo sites are available for reaction. However, our results show that the Mo{sub 6}S{sub 8} cluster is not as reactive as bulk MoS{sub 2} because it is unable to break the C-O bond of H{sub x}CO intermediates and therefore cannot produce hydrocarbons. Yet, the Mo{sub 6}S{sub 8} cluster is predicted to have moderate activity for converting CO{sub 2} and H{sub 2} to methanol. The overall reaction pathway involves the reverse water-gas shift reaction (CO{sub 2} + H{sub 2} {yields} CO + H{sub 2}O), followed by CO hydrogenation via HCO (CO + 2H{sub 2} {yields} CH{sub 3}OH) to form methanol. The rate-limiting step is CO hydrogenation to the HCO with a calculated barrier of +1 eV. This barrier is much lower than that calculated for a comparably sized Cu nanoparticle, which is the prototypical metal catalyst used for methanol synthesis from syngas (CO + H{sub 2}). Both the Mo and S sites participate in the reaction with CO{sub 2}, CO, and CH{sub x}O preferentially binding to the Mo sites, whereas S atoms facilitate H-H bond cleavage by forming relatively strong S-H bonds. Our study reveals that the unexpected activity of the Mo{sub 6}S{sub 8} cluster is the result of the interplay between shifts in the Mo d-band and S p-band and its unique cagelike geometry.« less