NMR for Catalyst Studies
EMSL Project ID
9103
Abstract
A detailed understanding of the mechanisms involved in a catalytic reaction requires that we identify the nature of the active sites and of reaction intermediates, and that we probe dynamic processes starting when reactants enter the reaction zone until final products elute from the system. For reactions involving simple species, in-situ techniques such as UV-visible and IR spectroscopies are typically used to probe the nature of adsorbed intermediates. For many important reactions, especially selective oxidations of organics, reaction products and intermediates are complex and difficult to identify using a single spectroscopic tool. Nuclear magnetic resonance spectroscopy at high field and under simulated reaction conditions can contribute in critical ways to the required analysis. Several well established surface-sensitive solid-state NMR techniques will be used to investigate the catalytic systems of interest. For example, singly- or doubly- labeled (13C or 2H) organic molecules can be adsorbed at ~5% monolayer coverage. The absorbed species mobility can be quenched by dropping the temperature to 50K or lower. The purpose of these experiments is simple: are the data consistent with proposed reaction mechanisms? Is there a single species on the surface or multiple forms? The results of these experiments (shielding tensors, bond distances and angles) can be used as boundary conditions for calculations and for comparison of analogous experiments using IR and other methods. Another experiment of particular interest is the adsorption of 15N-labelled NOx molecules on NOx conversion catalyst materials as probed by 15N NMR. Already, we have performed what we believe to be the first experiments to provide specific detail on the nature of the adsorbed NOx species on these important materials.
There are two specific current catalysis programs of interest as this EMSL use begins:
1) Early Transition Metal Oxides as Catalysts: Crossing Scales from Clusters to Single Crystals to Functioning Materials, a program funded by the DOE/OS/Basic Energy Sciences/Chemical Sciences; and
2) Fundamental Studies of NOx Adsorber Materials; a program funded by the DOE/EE/Office of FreedomCar and Vehicle Transportation.
Project Details
Start Date
2004-08-30
End Date
2006-10-11
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
An isotropic chemical shift–chemical shift anisotropic correlation experiment
using discrete magic angle turning
Jian Zhi Hu-, Jesse A. Sears, Ja Hun Kwak, David W. Hoyt, Yong Wang, Charles H.F. Peden
Institute for Interfacial Catalysis, Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, MS K8-98, Richland,
WA 99352, USA
Cheng Y, J Hoard, C Lambert, JH Kwak, and CHF Peden. 2008. "NMR Studies of Cu/zeolite SCR Catalysts Hydrothermally Aged with Urea." Catalysis Today 136(1-2):34-39. doi:10.1016/j.cattod.2008.01.019
Coordinatively Unsaturated Al3+ Centers as Binding Sites for Active Catalyst Phases of Platinum on g-Al2O3
Ja Hun Kwak, Jianzhi Hu, Donghai Mei, Cheol-Woo Yi, Do Heui Kim, Charles H. F. Peden, Lawrence F. Allard, Janos Szanyi
18 May 2009; accepted 24 July 2009 10.1126/science.1176443
Direct Observation of the Active Center for Methane Dehydroaromatization Using an Ultrahigh Field 95Mo NMR Spectroscopy
Heng Zheng, Ding Ma, Xinhe Bao, Jian Zhi Hu, Ja Hun Kwak, Yong Wang, and Charles H. F. Peden
Publication Date (Web): March 1, 2008 | doi: 10.1021/ja7110916
Herrera JE, JH Kwak, JZ Hu, Y Wang, and CHF Peden. 2008. "Effects of novel supports on the physical and catalytic properties of tungstophosphoric acid for alcohol dehydration reactions." Topics in Catalysis 49(3-4):259-267. doi:10.1007/s11244-008-9081-4
Kwak, J.H.; Hu, J.Z.; Kim, D.H.; Szanyi, J.; Peden, C.H.F. "Penta-coordinated Al3+ Ions as Preferential Nucleation Sites for BaO on γ-Al2O3: an Ultra-High Magnetic Field 27Al MAS NMR Study." J. Catal. 251 (2007) 189-194.
Kwak JH, JZ Hu, AC Lukaski, DH Kim, J Szanyi, and CHF Peden. 2008. "The Role of PentaCoordinated Al3+ Ions in the High Temperature Phase Transformation of γ-Al2O3." Journal of Physical Chemistry C 112(25):9486–9492. doi:10.1021/jp802631u
Mei D, JH Kwak, JZ Hu, SJ Cho, J Szanyi, L Allard, and CHF Peden. 2010. "The Unique Role of Anchoring Penta-coordinated Al3+ Sites in the Sintering of ? Al2O3-supported Pt Catalysts ." The Journal of Physical Chemistry Letters 1:2688–2691. doi:10.1021/jz101073p
New approaches for characterizing sensor and other modern complex materials
D. R. Baer, M. H. Engelhard, A. F. Felmy, J. J. Ford, A. S. Lea, P. Nachiumthu, L. Saraf, J. A. Sears and S.Thevuthasan
Studies of the Active Sites for Methane Dehydroaromatization Using Ultrahigh-Field Solid-State 95Mo NMR Spectroscopy
Jian Zhi Hu,-,? Ja Hun Kwak,? Yong Wang,? Charles H. F. Peden,-,? Heng Zheng,?,§ Ding Ma, and Xinhe Bao?
Institute for Interfacial Catalysis, Pacific Northwest National Laboratory, P.O. Box 999, MS K8-98, Richland, Washington 99352, U.S.A., State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P.R. China, and Southwest Research & Design Institute of Chemical Industry in Chengdu, China
Journal of Physical Chemistry C 113 (2009) 2936-2942.
Understanding the nature of surface nitrates in BaO/γ-Al2O3 NOx storage materials: A combined experimental and theoretical study
Ja Hun Kwak a, Donghai Mei a,∗, Cheol-Woo Yi a,1, Do Heui Kima, Charles H.F. Peden a, Lawrence F. Allard b,
János Szanyi a,∗
a Institute for Interfacial Catalysis, Pacific Northwest National Laboratory, P.O. Box 999, MSIN K8-80, Richland, WA 99352, USA
b High Temperature Materials Laboratory, Oak Ridge National Laboratory, TN, USA
Journal of Catalysis 261 (2009) 17-22.