Extension and Application of Multivariate Curve Resolution-Alternating
Xi Shibo
Institute of Chemical and Engineering Sciences, A*STAR, Singapore; Singapore Synchrotron Light Source, National University of Singapore, Singapore
EXTENDED ABSTRACT: Large amounts of data are generally produced from high-throughput materials structural characterization, such as in-situ and/or time resolved X-ray Absorption Fine Structure (XAFS). Traditionally, time-dependent XAFS are processed and analyzed using principal component analysis method implemented by software such as SIXPack, WINXAS, ATHENA, etc., and it is very challenging to comprehensively analyze the results due to their large data sizes and highly complex data structures. To overcome these barriers, it is obligatory to develop advanced data analysis approaches to handle the increasingly large time-dependent XAFS data. In this report, we focused on the method development of using Multivariate Curve Resolution- Alternating Least Squares (MCR-ALS) approaches. We aimed to effectively extract the essential information present in the large and complex time-dependent XAFS data. As a case study, XAFS data of in-situ characterization of oxidation/reduction of copper in Cu-CHA SCR catalysts will be analyzed using MCR-ALS [1,2]. This study will also help us to understand the processes that take place in SOx-poisoned Cu-zeolite catalysts. Moreover, the characterization of Cu-species formation in SO2- poisoned Cu CHA catalysts during activation under oxidizing and reducing conditions could lead to further progress in developing poisoning-tolerant catalysts. In this study the interaction of SO2 with the Cu sites of the Cu-SSZ-13 catalyst is examined, using experimental sets of in situ temperature dependent Cu Kedge XAFS spectra. Experimental XAFS data were processed using MCR-ALS algorithm, which was combined with DFTassisted X ray absorption near-edge structure (XANES) calculations. Wavelet transforms were applied in the analysis of extended X-ray absorption fine structure (EXAFS) data. SCR-performance measurements and other characterization methods were also used to determine the correlations between the SCR performance and Cuspeciation behavior of the SO2-poisoned catalyst.
REFERENCES
[1] Bergman, Susanna L., Sandra Dahlin, Vitaly V. Mesilov, Yang Xiao, Johanna Englund, Shibo Xi, Chunhua
Tang, Magnus Skoglundh, Lars J. Pettersson, and Steven L. Bernasek, Applied Catalysis B: Environmental 269,
118722 (2020).
[2] Mesilov, Vitaly, Sandra Dahlin, Susanna L. Bergman, Shibo Xi, Joonsoo Han, Louise Olsson, Lars J.
Pettersson, and Steven L. Bernasek, Applied Catalysis B: Environmental 299, 120626 (2021).
Dr. Xi Shibo obtained his B.S. degree from Sichuan University (P.R. of China), his Ph.D. in OPTICS from Institute of High Energy Physics, Chinese Academy of Sciences (P.R. of China). He joined Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research (Singapore) in 2012. Xi Shibo is the beamline scientist of X-ray Absorption Fine structure for catalysis (XAFCA) beamline of Singapore Synchrotron Light Source (SSLS). His research interest focuses on In-situ X-ray absorption fine structure (XAFS) study on catalysis, XAFS data processing and interpretation, electronic structure study based on combination of DFT and XAFS etc. He has so far published 179 research papers in peer-reviewed academic journals with about 6000 total citations and H index of 40. He has been working intensively with some of the major international synchrotron light sources, such as Diamond Light Source, Beijing Synchrotron Radiation Facility, Shanghai Synchrotron Radiation Facility and National Synchrotron Light Source II. To promote catalytic research in Singapore, in addition to undertaking the research tasks of ICES, he has also been working closely with about twenty research groups at NUS and NTU.