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205. Support effect of Ni/mesoporous silica catalysts for CO2 reforming of CH4.

Author

Chen, Jing, Piao, Wen Xiang, Jin, Long Yi, Li, Zhenghua, Zhang, Fan, Kim, Ji Man, and Jin, Mingshi

Subjects
MESOPOROUS silica, CATALYSTS, CATALYSIS, X-ray diffraction, ELECTRON microscopy
Abstract

Abstract: Mesoporous silica KIT-6-, SBA-15-, and MCM-41-supported Ni catalysts (Ni/KIT-6, Ni/SBA-15, and Ni/MCM-41) were prepared via impregnation method and studied for CO2 reforming of CH4. The catalysts were characterized by X-ray diffraction analysis, N2 physisorption measurements, scanning electron microscopy, transmission electron microscopy, and temperature-programmed oxidation (O2-TPO). The Ni/KIT-6 catalyst exhibited higher catalytic activity and long-term stability compared with Ni/SBA-15 or Ni/MCM-41. The conversion of CH4 and CO2 over Ni/KIT-6 was 99 and 99 %, respectively. The superior catalytic behavior of Ni/KIT-6 is closely related to the large-pore cubic Ia3d structure of KIT-6, which enhanced dispersion of Ni nanoparticles, reduced carbon deposition, and increased diffusion of reactant and products.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Published
2018
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206. Highly efficient mesoporous WOx/KIT-6 catalysts for oxidative desulfurization of dibenzothiophene with hydrogen peroxide.

Author

Li, Zhenghua, Li, Chengbin, Park, Su Bin, Hong, Gyoung Hee, Park, Jin Seo, Song, Byung Jin, Lee, Chul Wee, and Kim, Ji Man

Subjects
MESOPOROUS silica, MESOPORES, TUNGSTEN oxides, DESULFURIZATION, ORGANIC compounds
Abstract

Oxidative desulfurization (ODS) of organic compounds containing sulfur element from a model oil was performed using tungsten oxide catalysts supported on mesoporous silica with cubic Ia3d mesostructure, well-defined mesopores (7.2 nm), high surface area (719 m2/g), and three-dimensional pore network (WOx/KIT-6). The prepared WOx/KIT-6 catalysts (5-20 wt% WOx) were characterized by X-ray diffraction analysis, N2 sorption measurements, electron microscopy, H2-temperature programmed reduction, Raman spectroscopy, and thermogravimetric analysis. Among the mesoporous catalysts, 10 wt% WOx/KIT-6 exhibited the best catalytic performance. Sulfur-containing organic compounds, such as dibenzothiophene, 4,6-dimethyldibenzothiophene, and benzothiophene, were completely (100 %) removed from the model oil over 10 wt% WOx/KIT-6 catalyst in 2 h. In addition, the catalyst could be reused several times with only slight decrease in catalytic activity. [ABSTRACT FROM AUTHOR]

Published
2018
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207. Mild hydrodeoxygenation of phenolic lignin model compounds over a FeReOx/ZrO2 catalyst: zirconia and rhenium oxide as efficient dehydration promoters.

Author

Sirous-Rezaei, Pouya, Jae, Jungho, Ha, Jeong-Myeong, Ko, Chang Hyun, Kim, Ji Man, Jeon, Jong-Ki, and Park, Young-Kwon

Subjects
ZEOLITES, PHENOLS, DEHYDRATION reactions
Abstract

Strong adsorption of phenolics on zeolite acid sites causes high trapping inside zeolite channels and low catalytic activity of zeolite-supported catalysts in atmospheric pressure hydrodeoxygenation (HDO) of lignin-derived phenolics. This adsorption is more severe at low temperatures, and restricts the atmospheric HDO of phenolics to high reaction temperatures. The purpose of this research was to develop a catalyst with low phenolic trapping potential and high HDO efficiency under mild reaction conditions. Among the tested catalysts (Fe/HBeta, FeReOx/HBeta, Fe/MCM-41, ReOx/MCM-41, FeReOx/MCM-41, Fe/ZrO2 and FeReOx/ZrO2), the novel catalyst of FeReOx/ZrO2 exhibited the highest catalytic efficiency for mild-condition (pressure: 1 atm and temperature ＜350 °C) HDO of phenolics (guaiacol, m-cresol and anisole), and led to the selective production of BTX aromatics. Compared to Fe/HBeta(38) as a zeolite-supported catalyst, FeReOx/ZrO2 displayed remarkably enhanced performance, and its catalytic activity for the HDO of m-cresol at 350 °C was almost twice higher than that of Fe/HBeta(38) at 500 °C. Importantly, FeReOx/ZrO2 revealed a high HDO efficiency (BTX yield of 50.5 wt% with phenolic trapping below 5 wt%) at a low temperature of 250 °C, while Fe/HBeta(38) almost lost its entire catalytic activity at this temperature, and gave a low BTX yield of 3.0 wt% with a high trapped phenolic yield of 83.1 wt%. The remarkable catalytic activity of FeReOx/ZrO2 in the HDO of phenolics at atmospheric pressure and temperatures as low as 250 °C is a result of its mesoporosity and oxophilicity as well as its well-balanced acidity induced by both rhenium oxide and zirconia support causing a high dehydration efficiency. [ABSTRACT FROM AUTHOR]

Published
2018
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225. New Insight into the Reaction Mechanism for Exceptional Capacity of Ordered Mesoporous SnO2 Electrodes via Synchrotron-Based X-ray Analysis

Author

Kim, Hyunchul, primary, Park, Gwi Ok, additional, Kim, Yunok, additional, Muhammad, Shoaib, additional, Yoo, Jaeseung, additional, Balasubramanian, Mahalingam, additional, Cho, Yong-Hun, additional, Kim, Min-Gyu, additional, Lee, Byungju, additional, Kang, Kisuk, additional, Kim, Hansu, additional, Kim, Ji Man, additional, and Yoon, Won-Sub, additional

Published
2014
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232. Metal–Organic Framework@Microporous Organic Network: Hydrophobic Adsorbents with a Crystalline Inner Porosity

Author

Chun, Jiseul, primary, Kang, Sungah, additional, Park, Nojin, additional, Park, Eun Ji, additional, Jin, Xing, additional, Kim, Kwang-Dae, additional, Seo, Hyun Ook, additional, Lee, Sang Moon, additional, Kim, Hae Jin, additional, Kwon, Woo Hyun, additional, Park, Young-Kwon, additional, Kim, Ji Man, additional, Kim, Young Dok, additional, and Son, Seung Uk, additional

Published
2014
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237. Exceptional Lithium Storage in a Co(OH)2Anode: Hydride Formation

Author

Kim, Hyunchul, Choi, Woon Ih, Jang, Yoonjung, Balasubramanian, Mahalingam, Lee, Wontae, Park, Gwi Ok, Park, Su Bin, Yoo, Jaeseung, Hong, Jin Seok, Choi, Youn-Suk, Lee, Hyo Sug, Bae, In Tae, Kim, Ji Man, and Yoon, Won-Sub

Abstract

Current lithium ion battery technology is tied in with conventional reaction mechanisms such as insertion, conversion, and alloying reactions even though most future applications like EVs demand much higher energy densities than current ones. Exploring the exceptional reaction mechanism and related electrode materials can be critical for pushing current battery technology to a next level. Here, we introduce an exceptional reaction with a Co(OH)2material which exhibits an initial charge capacity of 1112 mAh g–1, about twice its theoretical value based on known conventional conversion reaction, and retains its first cycle capacity after 30 cycles. The combined results of synchrotron X-ray diffraction and X-ray absorption spectroscopy indicate that nanosized Co metal particles and LiOH are generated by conversion reaction at high voltages, and CoxHy, Li2O, and LiH are subsequently formed by hydride reaction between Co metal, LiOH, and other lithium species at low voltages, resulting in a anomalously high capacity beyond the theoretical capacity of Co(OH)2. This is further corroborated by AIMD simulations, localized STEM, and XPS. These findings will provide not only further understanding of exceptional lithium storage of recent nanostructured materials but also valuable guidance to develop advanced electrode materials with high energy density for next-generation batteries.

Published
2018
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