TY - JOUR
T1 - How to scrutinize adsorbed intermediates observed by in situ spectroscopy
T2 - Analysis of Coverage Transients (ACT)
AU - Ted Oyama, S.
AU - Yun, Gwang Nam
AU - Ahn, So Jin
AU - Bando, Kyoko K.
AU - Takagaki, Atsushi
AU - Kikuchi, Ryuji
N1 - Funding Information:
This work was supported by the Japan Science and Technology Agency under the CREST program, Grant Number JPMJCR16P2, the US Department of Energy under grant DE-FG02-96ER14669, and a Grand-in-Aid for Scientific Research (B) (no. 26289301) of JSPS, Japan. The XAFS measurements were performed under the approval of the Photon Factory Program Advisory Committee (Proposal Nos. 2014G619 and 2016G573).
Funding Information:
This work was supported by the Japan Science and Technology Agency under the CREST program, Grant Number JPMJCR16P2, the US Department of Energy under grant DE-FG02-96ER14669, and a Grand-in-Aid for Scientific Research (B) (no. 26289301) of JSPS, Japan. The XAFS measurements were performed under the approval of the Photon Factory Program Advisory Committee (Proposal Nos. 2014G619 and 2016G573).
Publisher Copyright:
© 2020 Elsevier Inc.
PY - 2021/2
Y1 - 2021/2
N2 - The understanding of catalytic mechanisms is enhanced by the observation of surface intermediates at reaction conditions using spectroscopic techniques, but this is insufficient, as the observed species may not be involved in the reaction. This work describes a general method of analysis of hydrogenation or oxidation reactions which uses transient spectroscopic data to determine whether an adsorbed species is a reactive intermediate or a spectator on the surface. The assumptions and limitations of the method are summarized. Although the technique is approximate, it is easy to implement, and provides order-of-magnitude estimates of the rate of reaction of an intermediate. The method consists of measuring the change of coverage of the species with time, dθ/dt, during adsorption in inert gas or at reaction conditions. An example is given with the hydrodeoxygenation of the model compound γ-valerolactone (GVL) using a Ni2P/MCM-41 catalyst, one of the most effective catalysts reported for the transformation. The reaction is relevant to the upgrading of bio-oil derived from pyrolysis of lignocellulosic feedstocks. The kinetics of the reaction and observation by in situ infrared spectroscopy of adsorbed GVL and its transformation to pentanoic acid are consistent with a Langmuir-Hinshelwood mechanism. Analysis by in situ transient X-ray absorption fine structure shows that the adsorbed GVL is a true reaction intermediate.
AB - The understanding of catalytic mechanisms is enhanced by the observation of surface intermediates at reaction conditions using spectroscopic techniques, but this is insufficient, as the observed species may not be involved in the reaction. This work describes a general method of analysis of hydrogenation or oxidation reactions which uses transient spectroscopic data to determine whether an adsorbed species is a reactive intermediate or a spectator on the surface. The assumptions and limitations of the method are summarized. Although the technique is approximate, it is easy to implement, and provides order-of-magnitude estimates of the rate of reaction of an intermediate. The method consists of measuring the change of coverage of the species with time, dθ/dt, during adsorption in inert gas or at reaction conditions. An example is given with the hydrodeoxygenation of the model compound γ-valerolactone (GVL) using a Ni2P/MCM-41 catalyst, one of the most effective catalysts reported for the transformation. The reaction is relevant to the upgrading of bio-oil derived from pyrolysis of lignocellulosic feedstocks. The kinetics of the reaction and observation by in situ infrared spectroscopy of adsorbed GVL and its transformation to pentanoic acid are consistent with a Langmuir-Hinshelwood mechanism. Analysis by in situ transient X-ray absorption fine structure shows that the adsorbed GVL is a true reaction intermediate.
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U2 - 10.1016/j.jcat.2020.10.029
DO - 10.1016/j.jcat.2020.10.029
M3 - Article
AN - SCOPUS:85101638934
VL - 394
SP - 273
EP - 283
JO - Journal of Catalysis
JF - Journal of Catalysis
SN - 0021-9517
ER -