• Title, Summary, Keyword: mesoporous alumina

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Synthesis of Thermally Stable Mesoporous Alumina by using Bayberry Tannin as Template in Aqueous System

  • Liu, Jing;Huang, Fuming;Liao, Xuepin;Shi, Bi
    • Bulletin of the Korean Chemical Society
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    • v.34 no.9
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    • pp.2650-2656
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    • 2013
  • Mesoporous alumina was synthesized using bayberry tannin (BT) as template. This novel synthesis strategy was based on a precipitation method associated with aluminum nitrate as the source of aluminum in an aqueous system. $N_2$ adsorption/desorption, XRD, SEM and TEM were used to characterize the as-prepared mesoporous alumina. The results showed that the mesoporous alumina possessed crystalline pore wall, high specific surface area, narrow pore distribution and excellent thermal stability. Moreover, the surface area and pore size of the mesoporous alumina can be tuned by changing the experimental parameters. Further, the mesoporous alumina was investigated as the support of palladium catalyst ($Pd-Al_2O_3{^*}$) for the hydrogenation of propenyl, styrene and linoleic acid. For comparison, the reference catalyst ($Pd-Al_2O_3$) prepared without barberry tannin was also employed for the catalytic hydrogenation. The experimental results showed that $Pd-Al_2O_3{^*}$ exhibited the superior catalytic performance than $Pd-Al_2O_3$ for all the investigated substrates, especially for the hydrogenation of linoleic acid with larger molecular.

Effect of Al Precursor Type on Mesoporous Alumina Particles Prepared by Spray Pyrolysis (분무열분해공정에 의한 메조기공 알루미나 제조에 있어 Al 전구체 영향)

  • Kim, Joo-Hyun;Jung, Kyeong-Youl;Park, Kyun-Young
    • Journal of Korean Powder Metallurgy Institute
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    • v.17 no.3
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    • pp.209-215
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    • 2010
  • Mesoporous alumina particles were prepared by spray pyrolysis using cetyltrimethyl-ammonium bromide (CTAB) as a structure directing agent and the effect of Al precursor types on the texture properties was studied using $N_2$ adsorption isotherms, small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The surface area and the microstructure of alumina particles were significantly influenced by the Al precursor type. The largest BET surface area was obtained when Al chloride was used, whereas alumina particles prepared from Al acetate had the largest pore volume. According to small-angle X-ray scattering (SAXS) analysis, the alumina powders prepared using nitrate and acetate precursors had a clear single SAXS peak around $2{\theta}=1.0{\sim}1.5^{\circ}$, indicating that regular mesopores with sponge-like structure were produced. On the basis of TEM, SAXS, and $N_2$ isotherm results, the chloride precursor was most profitable to obtain the largest surface area ($265\;m^2/g$), whereas, the nitrate precursor is useful for the preparation of non-hollow mesoporous alumina with regular pore size, maintaining high surface area (${\sim}233\;m^2/g$).

Preparation of AlN Powder Using Mesoporous Alumina and Its Characterization (메조포러스 알루미나를 이용한 AlN 분말 제조 및 특성분석)

  • Kim, Eun Bee;Lee, Yoon Joo;Shin, Dong Geun;Kwon, Woo Teck;Kim, Soo Ryong;Kang, Mi Sook;Kim, Young Hee
    • Journal of the Korean Ceramic Society
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    • v.51 no.6
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    • pp.544-548
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    • 2014
  • Aluminum nitride was synthesized using a carbothermal method from mesoporous alumina having a high surface area (> $1,000m^2/g$) as an aluminum source and CNTs (carbon nano tubes) as a carbon source. In this case the mesoporous alumina was used as the starting material instead of ${\alpha}-Al_2O_3$ with the expectation that the mesopores in mesoporous alumina act as channels for N2 gas and elimination of CO generated as by-product. It is also expected that the synthetic temperature should be lower compared to the use of ${\alpha}-Al_2O_3$ as a starting material due to its high surface area. The crystallinity of the produced aluminum nitride was studied by XRD and FT-IR, and the microstructure was investigated by FE-SEM. Also the purity of the aluminum nitride was analyzed through N/O determinator and ICP analysis.

Synthesis and Characterization of Sol-Gel Derived Mesoporous Titania/Alumina Membranes (솔젤법에 의한 메조기공 티타니아/알루미나 막의 제조 및 기체투과 특성)

  • Kwon, Hyuk-Taek;Kim, Jin-Soo
    • Membrane Journal
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    • v.21 no.3
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    • pp.229-235
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    • 2011
  • In this study, mesoporous titania/alumina membranes were prepared by sol-gel method. Pore structure and phase composition of titania/alumina membranes could be changed by calcination temperature. The addition of alumina into titania membranes retarded anatase-to-rutile phase transformation, resulting in stabilization of pore structures. The 5 time dip-coated membrane calcined at $450^{\circ}C$ is about $10.3{\mu}m$ in thickness with an average pore size of 5 nm. Hydrogen and nitrogen permeances through the membrane were $17.1{\times}10^{-7}mol/m^2{\cdot}s{\cdot}Pa$ and $4.7{\times}10^{-7}mol/m^2{\cdot}s{\cdot}Pa$, respectively. These data were explained by the Knudsen diffusion mechanism.

Adsorption of ammonia using mesoporous alumina prepared by a templating method

  • Yeom, Changjoo;Kim, Younghun
    • Environmental Engineering Research
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    • v.22 no.4
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    • pp.401-406
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    • 2017
  • Ammonia, $NH_3$, is a key chemical widely used in chemical industries and a toxic pollutant that impacts human health. Thus, there is a need for the development of effective adsorbents with high uptake capacities to adsorb $NH_3$. An adsorbent with a high surface area and a small pore size is generally preferred in order to have a high capacity for the removal of $NH_3$. The use inorganic nanoporous materials as gas adsorbents has increased substantially and emerged as an alternative to zeolite and activated carbon. Herein, mesoporous alumina (MA) was prepared and used as an $NH_3$ adsorbent. MA showed good pore properties such as a uniform pore size and interlinked pore system, when compared to commercial adsorbents (activated carbon, zeolite, and silica powder). MA has free hydroxyl groups, serving as useful adsorption sites for $NH_3$. In an adsorption isotherm test, MA exhibited 4.7-6.5 times higher uptake capacities for $NH_3$ than commercial adsorbents. Although the larger surface areas of adsorbents are important features of ideal adsorbents, a regular and interlinked adsorbent pore system was found to be a more crucial factor to adsorb $NH_3$.

Oxidative Dehydrogenation of n-Butane over Cr Catalysts Supported on Alumina and SBA-15 (Cr이 담지 된 알루미나, SBA-15 촉매에서 n-부탄의 산화적 탈수소화 반응)

  • Shin, Jin Hyun;Shin, Jin Ho;Cho, Deug Hee;Ko, Moon Kyu
    • Korean Chemical Engineering Research
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    • v.51 no.3
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    • pp.364-369
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    • 2013
  • Oxidative dehydrogenation of n-butane over mesoporous Cr catalysts were studied. Catalysts were prepared by Cr impregnated method over Ti or Zr dispersed mesoporous support such as SBA-15, ${\gamma}$-alumina and characterized by XRD, SEM, TEM, FT-IR UV-Vis and ICP-AES. The effect of high surface area was not noticed appreciably in terms of conversion, but for Cr catalysts with Ti and Zr-incorporated on SBA-15 and ${\gamma}$-alumina. showed high selectivity of trans-2-butene.

Hydrogen Production by Steam Reforming of Liquefied Natural Gas (LNG) over Nickel Catalyst Supported on Surfactant-templated Mesoporous Alumina (계면활성제를 이용하여 제조된 중형기공성 알루미나 담체에 담지된 니켈촉매 상에서 액화천연가스(LNG)의 수증기개질반응에 의한 수소 제조)

  • Seo, Jeong-Gil;Youn, Min-Hye;Song, In-Kyu
    • Clean Technology
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    • v.15 no.1
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    • pp.47-53
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    • 2009
  • Mesoporous aluminas (A-C, A-A, and A-N) were prepared by a templating method using cationic(C), anionic(A), and non-ionic(N) surfactant as a structure-directing agent, respectively. Nickel catalysts supported on mesoporous alumina (Ni/A-C, Ni/A-A, and Ni/A-N) were then prepared by an impregnation method, and were applied to hydrogen production by steam reforming of liquefied natural gas (LNG). Regardless of surfactant type, nickel species were finely dispersed on the surface of mesoporous alumina in the calcined catalysts. It was revealed that interaction between nickel species and support in the reduced catalysts was strongly dependent on the identity of surfactant. LNG conversion and $H_2$ composition in dry gas increased in the order of Ni/A-C < Ni/A-A < Ni/A-N. It was found that catalytic performance increased with increasing nickel surface area in the reduced catalyst. Among the catalyst tested, Ni/A-N catalyst with the highest nickel surface area showed the best catalytic performance.

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Gas transport properties of alumina composite membranes

  • Lee, Hong-Joo;Hiroyuki Yamauchi;Hiroyuki Suda;Kenji Haraya
    • Proceedings of the Membrane Society of Korea Conference
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    • pp.128-131
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    • 2004
  • The composite mesoporous ceramic membranes were prepared with ${\gamma}$-alumina and poly (2, 6-dimethyl-l, 4-pyphenylene oxide) (PPO) on the surface of the macroporous $\alpha$-alumina ceramic membranes and the permeation results were compared with those of the $\alpha$-alumina membrane for large-scale applications. In the results of the transport experiments, the ceramic membranes gave high gas permeances mainly due to Knudsen diffusion and surface diffusion as an additional mechanism. And, the polymer modification increased the permeances of the strongly adsorbing gas components. In this study the modifications of alumina ceramic membranes could increase the gas permeation performances especially for the strongly absorbing gas components.

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Evaluation of Mesoporous Alumina Adsorbent for the Purification of Paclitaxel (Paclitaxel 정제를 위한 메조기공 알루미나 흡착제 평가)

  • Oh, Hyeon-Jeong;Jung, Kyeong Youl;Kim, Jin-Hyun
    • Microbiology and Biotechnology Letters
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    • v.41 no.2
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    • pp.176-182
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    • 2013
  • Several types of mesoporous alumina adsorbents with different physical properties were prepared by spray pyrolysis and were used for the separation/purification of the anticancer agent paclitaxel. The pore diameter of the adsorbents had a greater effect than did the surface area and the pore volume on the removal of plant-derived impurities. An appropriate pore diameter (~10.8 nm) was required for effective impurity removal. At a constant pore diameter, the surface area of the adsorbent affected not only the purity but also the yield of paclitaxel. Also, increasing the surface area of the adsorbent resulted in an increase in the adsorption of paclitaxel and impurities (biomass-derived tar and wax components). Removal of these impurities was confirmed by HPLC analysis of the absorbent after the treatment and TGA of the organic substances that were bound to the adsorbent.