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Title: The effect of ZnO addition on H 2 O activation over Co/ZrO 2 catalysts

Authors:
; ;
Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1351655
Grant/Contract Number:
FG02-05ER15712
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Catalysis Today
Additional Journal Information:
Journal Volume: 269; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-04 16:17:50; Journal ID: ISSN 0920-5861
Publisher:
Elsevier
Country of Publication:
Netherlands
Language:
English

Citation Formats

Davidson, Stephen D., Sun, Junming, and Wang, Yong. The effect of ZnO addition on H 2 O activation over Co/ZrO 2 catalysts. Netherlands: N. p., 2016. Web. doi:10.1016/j.cattod.2015.10.016.
Davidson, Stephen D., Sun, Junming, & Wang, Yong. The effect of ZnO addition on H 2 O activation over Co/ZrO 2 catalysts. Netherlands. doi:10.1016/j.cattod.2015.10.016.
Davidson, Stephen D., Sun, Junming, and Wang, Yong. 2016. "The effect of ZnO addition on H 2 O activation over Co/ZrO 2 catalysts". Netherlands. doi:10.1016/j.cattod.2015.10.016.
@article{osti_1351655,
title = {The effect of ZnO addition on H 2 O activation over Co/ZrO 2 catalysts},
author = {Davidson, Stephen D. and Sun, Junming and Wang, Yong},
abstractNote = {},
doi = {10.1016/j.cattod.2015.10.016},
journal = {Catalysis Today},
number = C,
volume = 269,
place = {Netherlands},
year = 2016,
month = 7
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.cattod.2015.10.016

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  • The effect of ZnO addition on the dissociation of H2O and subsequent effects on cobalt oxidation state and ethanol reaction pathway were investigated over Co/ZrO2 catalyst during ethanol steam reforming (ESR). Catalyst physical properties were characterized by BET, XRD, and TEM. To characterize the catalysts ability to dissociate H2O, Raman spectroscopy, H2O-TPO, and pulsed H2O oxidation coupled with H2-TPR were used. It was found that the addition of ZnO to cobalt supported on ZrO2 decreased the activity for H2O dissociation, leading to a lower degree of cobalt oxidation. The decreased H2O dissociation was also found to affect the reaction pathway,more » evidenced by a shift in liquid product selectivity away from acetone and towards acetaldehyde.« less
  • A systematic variation of the V{sub 2}O{sub 5} content of the title catalysts reveals a dependence of the activation energy of the selective catalytic reduction of nitric oxide by ammonia on the surface concentration of vanadia. A significant decrease in activation energy (from approximately 80 to 40 kJ/mol) is observed, as the vanadia surface concentration is increased (from 0.3 to 8 {micro}mol/m{sup 2}). The same results were obtained from tests conducted both in the presence and absence of H{sub 2}O and SO{sub 2}. A possible mechanistic explanation is discussed.
  • The apparent activation energies for both the generation of CH{sub 3}{sup {sm_bullet}} radicals and the overall consumption of CH{sub 4} during the oxidative coupling reaction are strongly influenced by the presence of CO{sub 2}. The intrinsic activation energy for the information of CH{sub 3}{sup {sm_bullet}} radicals over Li/MgO catalysts is 26 {plus_minus} 2 kcal/mol, a value that increases to 37 {plus_minus} 3 kcal/mol upon the addition of only 0.04 Torr of CO{sub 2} to the reagents. The activation energy approaches a limiting value of ca. 50 kcal/mol at a CO{sub 2} partial pressure of {ge}1 Torr. Thus, under typical catalyticmore » reaction conditions for the oxidative coupling of methane (e.g., 190 Torr of CH{sub 4}, 95 Torr of O{sub 2}), sufficient CO{sub 2} would be produced to attain this limiting value of E{sub a}. However, by operating at sufficiently low partial pressures and conversion levels, an E{sub a} of 32 kcal/mol was obtained during the oxidative coupling reaction. Temperature-programmed desorption of CO{sub 2} from Li/MgO produces a peak at 630{degrees}C, which is consistent with the role of CO{sub 2} as a poison for the catalytic reactions. 15 refs., 4 figs.« less
  • Supported Pt catalysts were modified by adding a second metal such as Co, Mo, Ni, Re, Ag, and Pd. The effects of a second metal on the sulfur resistance were first investigated by accelerated aging test reactions. The test reactions were hydrogenation of tetralin containing 1,000 ppm sulfur at 280 C, 380 psig, and H{sub 2}/oil (mol) = 2.7. The results indicated that Pd-Pt catalyst had the highest sulfur resistance. Aromatics reduction, hydrodesulfurization, and hydrodenitrogenation of straight run distillate diesel over supported Pt and Pd-Pt catalysts were further examined by long-term stability tests. The operation conditions of these tests aremore » the same as those run in a commercial diesel hydrotreating process. The results again indicated that the Pd-Pt catalyst exhibited much better catalytic performance. These results, together with electronic properties of the metal clusters on the catalysts characterized by FFT-IR spectroscopy, provide a basis to speculate the role of Pd in enhancing sulfur resistance; the Pd-Pt bimetallic interactions decrease the electron density of Pt and thereby inhibit the adsorption of H{sub 2}S.« less
  • The reaction intermediate and the reaction mechanism of deuterium addition and exchange of propene over a bimetallic alloy have been studied by microwave spectroscopy as well as by kinetic measurements. The isotopic distribution pattern of monodeuteropropene formed during the reaction changed considerably by alloying Pd or Pt with Cu and resembled that over Cu metal. However, the turnover frequency and apparent activation energy of the overall reaction did not change appreciably by alloying. These results indicate the change in the relative activity of reaction intermediates and suggest an important role of Cu in modifying the active sites and the reactionmore » mechanism. It is proposed that a new type of active site is formed by alloying Group VIII metals with Group IB metals; the interaction may be called the synergetic ligand effect.« less