| 1. |
Tamao Ishida, Tetsuo Honma, Kengo Nakada, Haruno Murayama, Tetsuya Mamba, Kurumi Kume, Yusuke Izawa, Masaru Utsunomiya, Makoto Tokunaga, Pd-catalyzed decarbonylation of furfural Elucidation of support effect on Pd size and catalytic activity using in-situ XAFS, Journal of Catalysis, 10.1016/j.jcat.2019.04.041, 374, 320-327, 2019.06, Palladium (Pd) clusters on zirconia (ZrO
2
) and single Pd atoms on ceria (CeO
2
) exhibited high catalytic activity and selectivity for decarbonylation of furfural to furan without additives in the liquid phase. To study the active size of Pd and changes in chemical states or structures during the reaction, in-situ X-ray absorption fine structure (XAFS) measurements were conducted. The size of Pd clusters consisting of less than 10 Pd atoms was maintained on ZrO
2
during the reaction. In contrast, single Pd atoms were aggregated during heating and only Pd clusters consisting of 13 atoms were present after the reaction. According to the in-situ XAFS results, the size of Pd particles did not gradually increase to Pd
13
clusters. Instead, Pd
13
clusters were partly formed from the beginning of the reaction, and the proportion of Pd
13
clusters increased with time while keeping the size of Pd
13
clusters. This result suggests that a single Pd atom is inactive, but Pd clusters are active for decarbonylation. Ab-initio calculation revealed that ZrO
2
(1 1 1) surface had lower adsorption and migration energies than CeO
2
(1 1 1), implying that Pd was easily diffused on the surface and stabilized as small Pd clusters.. |
| 2. |
Selective adsorption of 1,3-dimethyltrisulfane (DMTS) responsible for aged odour in Japanese sake using supported gold nanoparticles. |
| 3. |
Haruno Murayama, Takayuki Hasegawa, Yusuke Yamamoto, Misaki Tone, Moemi Kimura, Tamao Ishida, Tetsuo Honma, Mitsutaka Okumura, Atsuko Isogai, Tsutomu Fujii, Makoto Tokunaga, Chloride-free and water-soluble Au complex for preparation of supported small nanoparticles by impregnation method, JOURNAL OF CATALYSIS, 10.1016/j.jcat.2017.07.002, 353, 74-80, 2017.09, A novel simple and easy impregnation method for preparation of small gold (Au) nanoparticle (NP) catalysts (<3 nm) deposited on various supports including silica, which is difficult to be applied for conventional methods, has been developed. Chloride-free and water-soluble precursor, Au complexes coordinated with beta-alanine, were successful for the preparing Au NPs, which exhibited an average diameter less than 3 nm. Thermal behavior of the Au complex was investigated by TG-DTA and in situ XAFS. XAFS analyses and DFT calculations revealed a molecular structure of the Au complex to be square-planar coordination structure and mononuclear complex of Au3+. Lower decomposition and reduction temperature of the chloride-free Au complex prevented Au atoms from aggregating and from following growth of Au particles. The prepared Au/SiO2 showed high selectivity for hydrogenation of 1-nitro-4-vinylbenzene into 1-ethyl-4-nitorobenzene and good performance for removal of unpalatable aroma by means of adsorption of polysulfide molecules. (C) 2017 Elsevier Inc. All rights reserved.. |
| 4. |
Koji Kitada, Haruno Murayama, Katsutoshi Fukuda, Hajime Arai, Yoshiharu Uchimoto, Zempachi Ogumi, Effect of Potential Profile on Battery Capacity Decrease during Continuous Cycling, JOURNAL OF PHYSICAL CHEMISTRY C, 10.1021/acs.jpcc.6b12937, 121, 11, 6018-6023, 2017.03, The origin of the capacity decrease of lithium ion batteries during continuous charge/discharge cycling, as typified by battery operation in electric vehicles, is elucidated using LiNi1/3Co1/3Mn1/3O2 (NCM)-based composite electrodes. Electrochemical cycling tests without any rest process show the capacity decrease only during discharging. Reaction distribution analysis by operando energy -scanning confocal Xray diffraction indicates that considerable reaction inhomogeneity occurs on the lithiation of NCM during discharging, whereas the delithiation during charging proceeds homogeneously. It is shown that the reaction inhomogeneity caused by limited Li' transportation in the composite electrode is relaxed during charging owing to the potential profile of the NCMbased electrode, whereas no such relaxation occurs during discharging. This result demonstrates that the optimization of the electrode potential profile is important for good cydability of the batteries continuous charge/discharge cycling, in addition to improving Li+ transportation within the battery.. |
| 5. |
Tamao Ishida, Kurumi Kume, Kota Kinjo, Tetsuo Honma, Kengo Nakada, Hironori Ohashi, Takushi Yokoyama, Akiyuki Hamasaki, Haruno Murayama, Yusuke Izawa, Masaru Utsunomiya, Makoto Tokunaga, Efficient Decarbonylation of Furfural to Furan Catalyzed by Zirconia-Supported Palladium Clusters with Low Atomicity, CHEMSUSCHEM, 10.1002/cssc.201601232, 9, 24, 3441-3447, 2016.12, Decarbonylation of furfural to furan was efficiently catalyzed by ZrO2-supported Pd clusters in the liquid phase under a N-2 atmosphere without additives. Although Pd/C and Pd/Al2O3 have frequently been used for decarbonylation, Pd/ZrO2 exhibited superior catalytic performance compared with these conventional catalysts. Transmission electron microscopy and Xray absorption fine structure measurements revealed that the size of the Pd particles decreased with an increase in the specific surface area of ZrO2. ZrO2 with a high surface area immobilized Pd as clusters consisting of several (three to five) Pd atoms, whereas Pd aggregated to form nanoparticles on other supports such as carbon and Al2O3 despite their high surface areas. The catalytic activity of Pd/ZrO2 was enhanced with a decrease in particle size, and the smallest Pd/ZrO2 was the most active catalyst for decarbonylation. When CeO2 was used as the support, a decrease in Pd particle size with an increase in surface area was also observed. Single Pd atoms were deposited on CeO2 with a high surface area, with a strong interaction through the formation of a Pd-O-Ce bond, which led to a lower catalytic activity than that of Pd/ZrO2. This result suggests that zero-valent small Pd clusters consisting of more than one Pd atom are the active species for the decarbonylation reaction. Recycling tests proved that Pd/ZrO2 maintained its catalytic activity until its sixth use.. |
| 6. |
Koji Kitada, Haruno Murayama, Katsutoshi Fukuda, Hajime Arai, Yoshiharu Uchimoto, Zempachi Ogumi, Eiichiro Matsubara, Factors determining the packing-limitation of active materials in the composite electrode of lithium-ion batteries, JOURNAL OF POWER SOURCES, 10.1016/j.jpowsour.2015.09.105, 301, 11-17, 2016.01, The factors limiting the capacity of highly dense electrodes are elucidated by using composite electrodes for lithium-ion batteries, which consist of active materials LiNi(1/3)Co(1/3)Mni(1/3)O(2) (NCM), conductive additives and binders. Electrochemical tests of such 100-mu m-thick electrodes in 1 M LiPF6 electrolyte indicate that a highly dense electrode (with 18% porosity) shows a capacity density significantly lower than the other sparse electrodes on 1C charging/discharging. Detailed analysis using position sensitive in situ X-ray diffraction indicates that, unlike the other sparse electrodes, NCM on the current-collector side barely functions for this dense electrode, due to the poor accessibility of Li+ to the inner part of the electrode. Interestingly, 2 M and 0.3 M electrolytes promote the discharge and charge reactions, respectively, over the entire area of the electrode, although they exhibit lower conductivity than the 1 M electrolyte, which indicates the importance of the initial amount of Li+ in the electrolyte impregnated in the electrode pores. Thus, for a high-energy-density cell, the initial amount of Li+ and the Li+ transport significantly affect the rate capability, which governs the practical capacity of the cell under constant-current operation. (C) 2015 Elsevier B.V. All rights reserved.. |
| 7. |
Haruno Murayama, Koji Kitada, Katsutoshi Fukuda, Akio Mitsui, Koji Ohara, Hajime Arai, Yoshiharu Uchimoto, Zempachi Ogumi, Eiichiro Matsubara, Spectroscopic X-ray Diffraction for Microfocus Inspection of Li-Ion Batteries, JOURNAL OF PHYSICAL CHEMISTRY C, 10.1021/jp5029273, 118, 36, 20750-20755, 2014.09, We developed spectroscopic X-ray diffraction (XRD) analysis to visualize electrochemical reactions occurring at various locations in Li-ion batteries (LIBs). Continuous irradiation with monochromatic X-rays in an energy region using a confocal setup provided a fixed observation position on the order of several tens of microns. Unlike three-dimensionally position sensitive XRD analyses, e.g., angle-scanning XRD and energy-dispersive XRD, this energy-scanning XRD analysis with angle-scanning of the monochromator instead of the detector-scanning has the advantage of profile resolution, position sensitivity, and time-resolution for mapping concentration gradients and diffusion of Li+ associated with the electrochemical properties of LIBs. The microscopic structural inhomogeneity in a sheet-like composite electrode of LiNi1/3Co1/3Mn1/3O2 with a thickness of 150 mu m was successfully determined with a depth resolution of 50 mu m during cell operation. This work demonstrates the potential of spectroscopic XRD as a nondestructive and pinpoint analysis method, thus contributing to the development of high-performance LIBs.. |
| 8. |
Haruno Murayama, Naomi Hashimoto, Hideki Tanaka, Ag triangular nanoplates synthesized by photo-induced reduction: Structure analysis and stability, CHEMICAL PHYSICS LETTERS, 10.1016/j.cplett.2009.10.015, 482, 4-6, 291-295, 2009.11, Ag triangular nanoplates were synthesized by photoirradiation to AgNO(3) ethanol solution in the presence of polyvinylpyrrolidone (PVP) under anaerobic conditions at room temperature. High-resolution SEM and TEM observations revealed that thin Ag equilateral triangular nanoplates, each of which was a single crystal with sharp corners and flat faces presented by {1 1 1} planes, were produced. Analyses of XAFS and XPS have shown that these nanoplates are protected by coordination of O atoms in PVP molecules, not being oxidized as Ag(2)O. The nanoplates are inherently stable, though they were easily truncated and dissolved if mixed with oxygen or water. (C) 2009 Published by Elsevier B. V.. |
| 9. |
H. Murayama, D. Vitry, W. Ueda, G. Fuchs, M. Anne, J. L. Dubois, Structure characterization of orthorhombic phase in MoVTeNbO catalyst by powder X-ray diffraction and XANES, Applied Catalysis A: General, 10.1016/j.apcata.2006.10.050, 318, 137-142, 2006.12, The structure of the pure orthorhombic phase of the MoVTeNbO catalyst used for propane selective oxidation to acrylic acid was characterized by a combination of XANES and XRD. The vanadium K absorption pre-edge peak position due to 1s–3d transition obtained by XANES shows that average oxidation state of Vis 4.1+. The Rietveld XRD analysis refined the unit cell parameters, chemical formula, and geometric arrangement of the catalyst, particularly the positions and fractional occupancies of metal atoms. The unit cell is Pba2 with a = 2.1116 nm, b = 2.6594 nm, c = 0.4007 nm. The unit formula is Mo0.55(5+)Mo6.76
(6+)V1.52(4+)V0.17(5+)Te0.69(4+)Nb1.00(5+)Ox(2-) (28.34 < x < 28.69). The structure refinement of five-, six-, and seven-membered rings ofMO6 (M = Mo or V) determined that Nb5+ is localized in the pentagonal channel surrounded byMO6 octahedra, that Te4+ is localized in the hexagonal channel surrounded by MO6, and that the heptagonal channel is not occupied. Results revealed that Te4+ is only localized in the hexagonal channel at 70% occupancy. Te in the catalyst proves to be highly stable.. |
