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Title: Structural Identification of Zn xZr yO z Catalysts for Cascade Aldolization and Self-Deoxygenation Reactions

Here, complementary characterizations, such as nitrogen sorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), visible Raman, scanning transmission electron microscopy (STEM) coupled with elemental mapping, NH 3/CO 2 temperature programmed desorption (NH 3/CO 2-TPD), infrared spectroscopic analysis of adsorbed pyridine (Py-IR), and CO 2-IR, have been employed to identify the structure and surface chemistry (i.e., acid-base) of mixed Zn xZr yO z oxide catalysts of varied ratios of Zn/Zr. Atomically dispersed Zn 2+ species are present in the framework within a thin surface shell (1.5-2.0 nm) of ZrO 2 particles when the Zn/Zr ratio is smaller than 1/10; when the ratio is above this, both atomically dispersed Zn 2+ and ZnO clusters coexist in mixed Zn xZr yO z oxide catalysts. The presence of ZnO clusters shows no significant side effect but only a slight increase of selectivity to CO 2, caused by steam reforming. The incorporation of atomic Zn 2+ into the ZrO 2 framework was found to not only passivate strong Lewis acid sites (i.e., Zr-O-Zr) on ZrO 2, but to also generate new Lewis acid-base site pairs with enhanced Lewis basicity on the bridged O (i.e., Zr—o$$\curvearrowleft\atop{e\atop—}$$Zn). In the mixed ketone (i.e., acetone and methyl ethyl ketone (MEK)) reactions, while the passivation of strong acid sites can be correlated to the inhibition of side reactions, such as ketone decomposition and coking, the new Lewis acid-base pairs introduced enhance the cascade aldolization and self-deoxygenation reactions involved in olefin (C 3 =-C 6 =) production. More importantly, the surface acid-base properties change with varying Zn/Zr ratios, which in turn affect the cross- and self-condensation reactivity and subsequent distribution of olefins.
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [1] ;  [1] ;  [3] ;  [4]
  1. Washington State Univ., Pullman, WA (United States). The Gene and Linda Voiland School of Chemical Engineering and Bioengineering
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Inst. for Integrated Catalysis and Environmental Molecular Sciences Lab.
  3. Archer Daniels Midland Company, Chicago, IL (United States)
  4. Washington State Univ., Pullman, WA (United States). The Gene and Linda Voiland School of Chemical Engineering and Bioengineering; Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Inst. for Integrated Catalysis
Publication Date:
Grant/Contract Number:
AC05-76RL01830; FWP-47319; WSU002206
Type:
Accepted Manuscript
Journal Name:
Applied Catalysis. B, Environmental
Additional Journal Information:
Journal Name: Applied Catalysis. B, Environmental; Journal ID: ISSN 0926-3373
Publisher:
Elsevier
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division; USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 09 BIOMASS FUELS; 10 SYNTHETIC FUELS; 36 MATERIALS SCIENCE; Lewis acid-base pairs; aldolization; ketonization; mixed-metal oxide; oxygenates; olefins
OSTI Identifier:
1434662