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- 주제어 : Structure zeolite catalysts (검색결과 4 건)
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Fe 이온이 담지된 BEA 제올라이트 촉매의 열처리 온도에 따른 N2O 분해반응에 대한 영향
정기림 ( Gi Rim Jeong ),이승재 ( Seung Jae Lee ),유인수 ( In Soo Ryu ),문승현 ( Seung Hyun Moon ) 한국화학공학회 2013 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.51 No.5
철 이온을 담지시킨 BEA 제올라이트에서 N2O가 분해되는 반응을 조사하여 열처리 온도가 촉매의 활성에 미치는 영향을 고찰하였다. N2O 분해 반응 실험 결과, Fe/BEA 촉매에 대한 열처리 온도가 증가함에 따라 N2O 분해 활성이 현저히 줄어들었다. 열처리 온도의 증가에 따른 Fe/BEA 촉매의 입자모양 및 크기의 변화는 크지 않았지만, 열처리 온도 증가에 따라 비표면적이 크게 줄어들었다. 또한 열처리온도가 증가함에 따라 β 구조의 결정성이 크게 낮아지는 것을 확인하였고, 열처리 온도가 높아질수록 SiO 구조는 증가하거나 크게 변화가 없는 반면, Fe가 골격구조와 결합된 구조는 감소하는 것으로 판단되었다. 이와 같은 결과로 열처리 온도의 증가에 따라 알루미늄과 Fe가 결합된 β 구조가 붕괴되어 N2O 분해활성이 크게 저하되는 것으로 사료된다. The effect of heat-treatment temperature on the activity of catalysts was studied by investigating N2O decomposition reaction in Fe ion-supported BEA Zeolite. As a result of N2O decomposition reaction experiment, N2O decomposition activity significantly decreased as heat-treatment temperature of Fe/BEA catalyst increased. the shape and size of the particles of Fe/BEA catalyst following the rise of heat-treatment temperature did not display a significant change. But following the rise of the heat-treatment temperature, its surface area was significantly reduced. Also it was confirmed that as the heat-treatment temperature rose, the crystallization of β structure was greatly reduced. And as heattreatment temperature rose, while SiO structure either increased or did not exhibit much change, the structure of Fe bonded with lattice structure was speculated to decrease. From the stated results, it was concluded that the increase of heat-treatment temperature became the cause of the declined activity of catalysts by destruction of its β structure of bonding aluminium and Fe atoms.
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Jeon, Yukwon,Chi, Won Seok,Hwang, Jusoon,Kim, Do Hyun,Kim, Jong Hak,Shul, Yong-Gun Elsevier 2019 Applied Catalysis B Vol.242 No.-
<P><B>Abstract</B></P> <P>We developed a new class of acid-base bifunctional heterogeneous catalyst, which can be used in the transesterification of rapeseed oil for highly efficient biodiesel production. A simple Keggin-type HPA (heteropoly acid) functionalization on the surface of zeolitic imidazolate framework-8 (ZIF-8) nanoparticles, through an imidazolium medium, results in the bifunctional heterogeneous catalysts. The hybrid materials exhibit a novel hierarchically core-shell nanostructure, which provides a large surface area and interconnectivity, leading to a thin-wrinkled HPA shell at the surface of rhombic dodecahedral ZIF-8 core crystals. A strong ON hybrid bonding through an electrostatic effect in the hybrid materials demonstrates a strong interaction between the Keggin and imidazole units, which is one of the main driving forces of hybrid materials formation. Additionally, the transformation of the HPA/ZIF-8 ratio in the hybrid materials changes the acidity and basicity, thereby affecting catalyst activity. We used these bifunctional core-shell materials as environmentally friendly heterogeneous catalysts in the transesterification of rapeseed oil with methanol to produce a high-quality biodiesel. Of particular interest, the HPA-functionalized ZIF-8 catalyst with a proper HPA/ZIF-8 ratio shows a high FAME conversion of 98.02% along with high recyclability because of the sufficiently large surface area and bi-functionality of strong acidity. Furthermore, the HPA-functionalized ZIF-8 catalyst shows a high reaction efficiency of the benzyl alcohol oxidation process, indicating a great potential of our catalyst to a wide range of applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bifunctional heterogeneous catalyst was prepared using HPA functionalization on ZIF-8 nanoparticles. </LI> <LI> HPA/ZIF-8 materials showed core-shell structure with large surface area and interconnectivity. </LI> <LI> A high FAME conversion of 98.02% along with high recyclability was obtained. </LI> <LI> A high reaction efficiency of the benzyl alcohol oxidation process was also achieved. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>The core-shell structured heteropoly acid (HPA)-functionalized zeolitic imidazolate frameworks-8 (ZIF-8) nanoparticles were used as acidic and basic bifunctional, highly-porous, heterogeneous catalysts for efficient biodiesel production.</P> <P>[DISPLAY OMISSION]</P>
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Andrii Kostyniuk,David Bajec,Anze Prašnikar,Blaz Likozar 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.101 No.-
Producing bio-based aromatic substrates is becoming increasingly of (industrial) interest. In this mechanisticwork, the gas phase conversion of the biomass tar chemical model compounds (5 wt% naphthalene/95 wt% 1-methylnaphthalene) over the different pristine/metal-modified zeolites in acontinuous flow fixed bed reactor was investigated. Bifunctional redox acid process catalysts were synthesizedby wet impregnation method. The effect of the W (/Ni) metal formulation additives to the pristineH-beta, H-USY, H-Y, and H-ZSM-5 in the hydrocracking, hydrogenation, and isomerizationtransformation reactions of the mixture under applied ambient pressure was firstly studied. Structure,texture, morphology, acidity, composition and properties were determined by various analytical techniques. Results showed that the highest catalytic activity with a comparison to others was establishedover the 20 wt% W-beta with 96.0 mol% of the selectivity to 2-methylnaphthalene, the 93.3 mol% reactedtotal reactant after the 24 h time on stream, where ethylene/propane were predominating (80.5 wt%), andfacile manufacturing scalability. Detailed characterization methodologies have revealed that after theloading of W onto H-beta_support, a uniform functional distribution of particles, the dealumination offramework and strong interaction phenomena were observed, which led to an increase in the amountof Brønsted/Lewis/reduction surface sites, and hence, increase stability of the catalyst. In addition,equilibrium coke formation was detected, decreasing all estimated rates, undergoing also consequentexternal deactivation, blocking pores, and its burning-off regeneration being needed. While both spentW-modified (20 wt%)/unmodified H-beta/ZSM-5 exhibited the lowest carbon quantity, the same freshmaterials possessed the uppermost hierarchy factors.
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Anti-poisoning core-shell metal/ZIF-8 catalyst for selective alkene hydrogenation
Yin, H.,Choi, J.,Yip, A.C.K. Elsevier Science Publishers 2016 CATALYSIS TODAY - Vol.265 No.-
<P>We report a synthesis strategy for preparing a core-shell zeolitic imidazolate framework-8 (ZIF-8)-supported metal (gold or palladium) composite with catalytic selectivity and anti-poisoning properties. The catalytic performance of this ZIF-8/metal/ZIF-8 composite was investigated in catalytic alkene hydrogenation. The prepared ZIF-8/Pd/ZIF-8 composites exhibited high catalytic selectivity for 1-hexene over cis-cyclooctene and effectively protected the Pd particles from poisoning by thiophene during hydrogenation. The spent catalyst was almost fully regenerated after removing the adsorbed sulfur impurities. The reported core-shell catalyst design could be applicable to reactions in which the reactants to be processed contain components that could potentially poison the active sites. (C) 2015 Elsevier B.V. All rights reserved.</P>
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