Enhanced electrorheological activity of various alkaline earth metal-doped hollow silica/titania particles via synergetic effect of anti-sedimentation and dielectric property

윤창민,장정식 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

Various alkaline earth metal-doped hollow silica/titania particles (EMHST)are successfully fabricated via sol-gel method followed by sonication- mediated etching and re-deposition (SMER) method to study the effect of metal doping on electrorheological (ER) performance. Particularly, three kinds of alkaline earth metal hydroxides are used to synthesize alkaline earth metal (Ca, Sr, Ba)-doped hollow silica/titania particles. Noticeably, this simple etching method successfully increases both anti-sedimentation and dielectric property of ER fluids in one-step process. In particular, the EM-HST-based ER fluids exhibits higher shear stress compared to the non-metal doped hollow silica/titania- and non-hollow silica/titania-based ER fluids. This experiment suggests a simple method to increase the ER performance by facile etching method.

Preparation of 27Ni6Zr4O143M(M=Mg, Ca, Sr, or Ba)O/70 Zeolite Y Catalysts and Hydrogen-rich Gas Production by Ethanol Steam Reforming

김동진,Jun Su Lee,이가영,Byung-Hyun Choi,Mi-Jung Ji,SunminPark,강미숙 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.7

In this study the effects of adding alkaline-earth (IIA) metal oxides to NiZr-loaded Zeolite Y catalysts were investigated on hydrogen rich production by ethanol steam reforming (ESR). Four kinds of alkaline-earth metal (Mg, Ca, Sr, or Ba) oxides of 3.0% by weight were loaded between the Ni6Zr4O14 main catalytic species and the microporous Zeolite Y support. The characterizations of these catalysts were examined by XRD, TEM, H2- TPR, NH3-TPD, and XPS. Catalytic performances during ESR were found to depend on the basicity of the added alkaline-earth metal oxides and H2 production and ethanol conversion were maximized to 82% and 98% respectively in 27(Ni6Zr4O14)3MgO/70Zeolite Y catalyst at 600 oC. Many carbon deposits and carbon nano fibers were seen on the surface of 30Ni6Zr4O14/70Zeolite Y catalyst but lesser amounts were observed on alkaline-earth metal oxide-loaded 27(Ni6Zr4O14)3MO/70Zeolite Y catalysts in TEM photos after ESR. This study demonstrates that hydrogen yields from ESR are closely related to the acidities of catalysts and that alkaline-earth metal oxides reduce the acidities of 27(Ni6Zr4O14)3MO/70Zeolite Y catalysts and promote hydrogen evolution by preventing progression to hydrocarbons.

Preparation of 27Ni₆Zr₄O₁₄3M(M=Mg, Ca, Sr, or Ba)O/70 Zeolite Y Catalysts and Hydrogen-rich Gas Production by Ethanol Steam Reforming

Kim, Dongjin,Lee, Jun Su,Lee, Gayoung,Choi, Byung-Hyun,Ji, Mi-Jung,Park, Sun-Min,Kang, Misook Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.7

In this study the effects of adding alkaline-earth (IIA) metal oxides to NiZr-loaded Zeolite Y catalysts were investigated on hydrogen rich production by ethanol steam reforming (ESR). Four kinds of alkaline-earth metal (Mg, Ca, Sr, or Ba) oxides of 3.0% by weight were loaded between the $Ni_6Zr_4O_{14}$ main catalytic species and the microporous Zeolite Y support. The characterizations of these catalysts were examined by XRD, TEM, $H_2$-TPR, $NH_3$-TPD, and XPS. Catalytic performances during ESR were found to depend on the basicity of the added alkaline-earth metal oxides and $H_2$ production and ethanol conversion were maximized to 82% and 98% respectively in 27($Ni_6Zr_4O_{14}$)3MgO/70Zeolite Y catalyst at $600^{\circ}C$. Many carbon deposits and carbon nano fibers were seen on the surface of $30Ni_6Zr_4O_{14}$/70Zeolite Y catalyst but lesser amounts were observed on alkaline-earth metal oxide-loaded 27($Ni_6Zr_4O_{14}$)3MO/70Zeolite Y catalysts in TEM photos after ESR. This study demonstrates that hydrogen yields from ESR are closely related to the acidities of catalysts and that alkaline-earth metal oxides reduce the acidities of 27($Ni_6Zr_4O_{14}$)3MO/70Zeolite Y catalysts and promote hydrogen evolution by preventing progression to hydrocarbons.

Side reaction in the hydrogen and carbothermal reductions of BaO and BaCO3: The role of an infinitesimal amount of water

오주현,박지훈,강미정,정성철,Takeuchi Ichiro,정정현,이승훈 한국물리학회 2022 Current Applied Physics Vol.34 No.-

Alkaline earth (AE) metals are irreplaceable ingredients in the synthesis of AE metal-based antiperovskite oxides, and it can be achieved by a chemical reduction of a stable AE metal compound. In this study, hydrogen and carbothermal reduction of BaO and BaCO3 were attempted, and we here report an undesirable side reaction creating barium hydroxide (Ba(OH)2) as the product of the reaction with the small amount of water in ultra-high purity inert gas used in the reduction processes. Such side reaction pathways and products are hardly identifiable in a high-temperature reaction; yet, systematic investigations on phase evolutions using X-ray diffraction, IR spectroscopy, and thermogravimetric analysis enabled the detection of Ba(OH)2⋅xH2O. Unintentional creation of alkaline earth metal oxides in intermediate and subsequent hydration even under a negligible amount of H2O may lead to an unexpected loss of alkaline earth metal element and, consequently, its deficiency in a desired final product.

Effects of alkali- and alkaline-earth-metals on hydrogen generation during fluidized bed gasification of artificial waste

Tzu-Huan Peng,Chiou-Liang Lin,Hsien Chen 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.2

We evaluated the effects of Na, K, Ca, and the steam-to-biomass (S/B) ratio on gasification efficiency duringsyngas production. The results show that H2 production was positively correlated with the S/B ratio. However, increasesin the S/B ratio were limited because excessive steam decreased the reactor temperature and hampered the gasificationprocess. Regarding the effects of alkali metals on syngas composition, we found that the addition of either Na or Kincreased the molar percentages of H2 and CO, but decreased CH4 and CO2. The results also clearly show that the additionof Na or K improved the yield of syngas, the carbon conversion efficiency, and the cold gas efficiency. Improvementswere especially pronounced with K. Furthermore, Ca had different interactions with Na and K during gasification. WhenNa and Ca existed simultaneously, H2 production was enhanced.

Effect of Cation Substitution on the Lattice Vibration and Crystal Structure of Magnetic RuSr1.9A0.1GdCu2O8 (A = Ca, Sr, and Ba) Superconductors

Tae Woo Kim,양인상,황성주 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.11

The lattice vibration and crystal structure of alkaline earth metal-substituted RuSr1.9A0.1GdCu2O8 (A = Ca, Sr, and Ba) have been investigated with micro-Raman spectroscopy. The present RuSr1.9A0.1GdCu2O8 materials show not only several weak Raman peaks corresponding to the vibrations of OCu and ORu but also strong characteristic phonon lines related to OSr vibration mode. A comparison between the frequency of OSr vibration and the bond distances of (Ru‒OSr) and (Cu‒OSr) in the present ruthenocuprates reveals that the vibration energy of OSr is mainly dependent on the bond distance of (Ru‒OSr). The peak splitting of the OSr phonon lines was observed for the unsubstituted RuSr2GdCu2O8, suggesting the existence of two different (Ru‒OSr) bond distances. Such a peak splitting caused by the appearance of low-energy shoulder reflects the presence of internal charge transfer pathway from the RuO2 plane to the superconductive CuO2 one. After the substitution of Sr with Ca or Ba, the low-energy shoulder peak of OSr vibration becomes suppressed, underscoring the depression of internal charge transfer between the RuO2 and CuO2 planes. The weakened role of RuO2 layer as charge reservoir in the RuSr1.9A0.1GdCu2O8 (A = Ca, Ba) would be responsible for the depression of Tc upon the Ca/Ba substitution.

Effect of Cation Substitution on the Lattice Vibration and Crystal Structure of Magnetic RuSr_1.9A_0.1GdCu₂O₈ (A = Ca, Sr, and Ba) Superconductors

Kim, Tae-Woo,Yang, In-Sang,Hwang, Seong-Ju Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.11

The lattice vibration and crystal structure of alkaline earth metal-substituted $RuSr_{1.9}A_{0.1}GdCu_{2}O_{8}$ (A = Ca, Sr, and Ba) have been investigated with micro-Raman spectroscopy. The present $RuSr_{1.9}A_{0.1}GdCu_{2}O_{8}$ materials show not only several weak Raman peaks corresponding to the vibrations of $O_{Cu}$ and $O_{Ru}$ but also strong characteristic phonon lines related to $O_{Sr}$ vibration mode. A comparison between the frequency of $O_{Sr}$ vibration and the bond distances of (Ru$O_{Sr}$) and (Cu‒$O_{Sr}$) in the present ruthenocuprates reveals that the vibration energy of $O_{Sr}$ is mainly dependent on the bond distance of (Ru‒$O_{Sr}$). The peak splitting of the $O_{Sr}$ phonon lines was observed for the unsubstituted $RuSr_{1.9}A_{0.1}GdCu_{2}O_{8}$, suggesting the existence of two different (Ru‒$O_{Sr}$) bond distances. Such a peak splitting caused by the appearance of low-energy shoulder reflects the presence of internal charge transfer pathway from the $RuO_2$ plane to the superconductive $CuO_2$ one. After the substitution of Sr with Ca or Ba, the low-energy shoulder peak of $O_{Sr}$ vibration becomes suppressed, underscoring the depression of internal charge transfer between the $RuO_2$ and $CuO_2$ planes. The weakened role of $RuO_2$ layer as charge reservoir in the $RuSr_{1.9}A_{0.1}GdCu_{2}O_{8}$8 (A = Ca, Ba) would be responsible for the depression of $T_c$ upon the Ca/Ba substitution.

Physico-mechanical behaviour of alkali and alkaline earth metal-containing mica glass–ceramics: a comparative evaluation

Amit Mallik 한국세라믹학회 2020 한국세라믹학회지 Vol.57 No.5

Mica glass–ceramics are known for their superior mechanical strength, fracture toughness and machinability. Crystallization, microstructure and mechanical behaviour of alkali and alkaline earth metal-containing mica glasses based on K 2 O/SrO/ BaO·4MgO·Al 2 O 3 ·6SiO 2 ·2MgF 2 composition were investigated by diff erential thermal analysis, X-ray diff raction, scanning electron microscopy and microhardness indenter. A distinct crystallization exotherm was observed in the diff erential thermal analysis curve.The crystallization peak corresponded to the formation of K-fl uorphlogopite for K-glass, Sr-fl uorphlogopite for Sr-glass, and Ba-fl uorphlogopite for Ba-glass. XRD results revealed that the above-mentioned formations were the major phases, while alpha hexacelsian, enstatite, and mullite were the minor phases in K-, Sr-, and Ba-glass–ceramics. SEM results indicated that the “house of cards” microstructure appeared in Sr-glass–ceramics at lower crystallization temperature than in the K- and Ba-glass–ceramics. The physico-mechanical properties of Ba- and Sr-glass–ceramics were compared with K-glass ceramics, and it was found that Ba-glass–ceramics possessed superior crystallization, microstructure and mechanical strength than the other two glass ceramics.

Effect of alkali and alkaline earth metal on Co/CeO₂ catalyst for the water-gas shift reaction of waste derived synthesis gas

Lee, Yeol-Lim,Jha, Ajay,Jang, Won-Jun,Shim, Jae-Oh,Rode, Chandrashekhar V.,Jeon, Byong-Hun,Bae, Jong Wook,Roh, Hyun-Seog Elsevier 2018 Applied Catalysis A Vol.551 No.-

<P><B>Abstract</B></P> <P>We prepared a series of alkali (Na and K) and alkaline earth metal (Ca and Ba) promoted Co/CeO<SUB>2</SUB> catalysts to investigate the effect of the promoter on the catalytic performance of the catalyst in the high-temperature water-gas shift (WGS) reaction of waste derived synthesis gas. Interestingly, alkali metal promoted catalysts deactivated rapidly compared to alkaline earth metal promoted catalysts. Alkaline earth metal promoted catalysts showed relatively higher stability (> 50 h) even at a very high gas hourly space velocity of 143,000 h<SUP>−1</SUP>. X − ray diffraction (XRD) and transmission electron microscopy (TEM) results reveal that the higher stability of the alkaline earth metal promoted catalysts was due to the strong resistance to sintering, showing a relatively small crystallite size of metallic cobalt compared to the alkali metal promoted catalysts after WGS reaction.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Alkali and alkaline earth metal promoted Co/CeO<SUB>2</SUB> catalysts were tested for WGS. </LI> <LI> The alkaline earth metal promoted catalyst showed higher stability than others. </LI> <LI> The alkaline earth metal promoted catalyst maintained small crystallite size of Co°. </LI> <LI> The alkaline earth metal enhanced the sintering resistance of Co/CeO<SUB>2</SUB> catalyst. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A DFT Study on Alkali and Alkaline Earth Metal Encapsulated Fullerene-Like BeO Cluster

Ravaei, Isa,Beheshtian, Javad Korean Chemical Society 2017 대한화학회지 Vol.61 No.6

By using Density Functional Theory (DFT), we have performed alkali metal and alkaline earth metal inside fullerene-like BeO cluster (FLBeOC) in terms of energetic, geometric, charge transfer, work function and electronic properties. It has been found that encapsulated processes of the alkali metal are exothermic and thermodynamically more favorable than alkaline earth metal encapsulation, so that interaction energy ($E_{int}$) of the alkali metal encapsulation FLBeOC is in the range of -0.02 to -1.15 eV at level of theory. It is found that, the electronic properties of the pristine fullerene-like BeO cluster are much more sensitive to the alkali metal encapsulation in comparison to alkaline earth metal encapsulation. The alkali and alkaline earth metal encapsulated fullerene-like BeO cluster systems exhibit good sensitivity, promising electronic properties which may be useful for a wide variety of next-generation nano-sensor device components. The encapsulation of alkali and alkali earth metal may increase the electron emission current from the FLBeOC surface by reducing of the work function.