• Title/Summary/Keyword: composite catalysts

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Effects of Manganese Precursors on MnOx/TiO2 for Low-Temperature SCR of NOx (NOx제거용 MnOx-TiO2 계 저온형SCR 촉매의 Mn전구체에 따른 영향)

  • Kim, Janghoon;Shin, Byeong kil;Yoon, Sang hyeon;Lee, Hee soo;Lim, Hyung mi;Jeong, Yongkeun
    • Korean Journal of Metals and Materials
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    • v.50 no.3
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    • pp.201-205
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    • 2012
  • The effects of various manganese precursors for the low-temperature selective catalytic reduction (SCR) of $NO_x$ were investigated in terms of structural, morphological, and physico-chemical analyses. $MnO_x/TiO_2$ catalysts were prepared from three different precursors, manganese nitrate, manganese acetate(II), and manganese acetate(III), by the sol-gel method. The manganese acetate(III)-$MnO_x/TiO_2$ catalyst tended to suppress the phase transition from the anatase structure to the rutile or the brookite after calcination at $500^{\circ}C$ for 2 h. It also had a high specific surface area, which was caused by a smaller particle size and more uniform distribution than the others. The change of catalytic acid sites was confirmed by Raman and FT-IR spectroscopy and the manganese acetate(III)-$MnO_x/TiO_2$ had the strongest Lewis acid sites among them. The highest de-NOx efficiency and structural stability were achieved by using the manganese cetate(III) as a precursor, because of its high specific surface area, a large amount of anatase $TiO_2$, and the strong catalytic acidity.

Process optimization for biodiesel production from indigenous non-edible Prunus armeniaca oil

  • Singh, Deepak;Kumar, Veerendra;Sandhu, S.S.;Sarma, A.K.
    • Advances in Energy Research
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    • v.4 no.3
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    • pp.189-202
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    • 2016
  • This work emphasized optimum production of biodiesel using non-edible Prunus armeniaca (Bitter Apricot) oil via transesterification collected from the high altitude areas of Himachal Pradesh, India. In this study the author produced biodiesel through the process of transesterification by using an alkali catalyst with alcohol (methanol and ethanol), under the varying molar ratio (1:6, 1:9, 1:12), variable catalyst percentage (1% and 2%) and temperature ($70^{\circ}C$, $75^{\circ}C$, $80^{\circ}C$, $85^{\circ}C$). Furthermore, a few strong base catalysts were used that includes sodium hydroxide, potassium hydroxide, sodium metal and freshly prepared sodium methoxide. After screening the catalyst, response surface methodology (RSM) in connection with the central composite design (CCD) was used to statistically evaluate and optimize the biodiesel production operation using NaOH as catalyst. It was found that the production of biodiesel achieved an optimum level biodiesel yield with 97.30% FAME conversion under the following reaction conditions: 1) Methanol/oil molar ratio: 1:6, 2) Reaction time: 3h, 3) Catalyst amount: NaOH 2 wt. %, and 4) Reaction temperature: $85^{\circ}C$. The experimental results showed that the optimum production and conversion of biodiesel through the process of transesterification could be achieved under an optimal set of reaction conditions. The biodiesel obtained showed appropriate fuel properties as specified in ASTM, BIS and En- standards.

Synthesis of CdxZn1-xS@MIL-101(Cr) Composite Catalysts for the Photodegradation of Methylene Blue

  • Yang, Shipeng;Peng, Siwei;Zhang, Chunhui;He, Xuwen;Cai, Yaqi
    • Nano
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    • v.13 no.10
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    • pp.1850118.1-1850118.17
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    • 2018
  • Nanoparticles of the semiconductor catalyst $Cd_xZn_{1-x}S$ were embedded into the metal organic framework MIL-101(Cr) to obtain $Cd_xZn_{1-x}S@MIL-101$(Cr) nanocomposites. These materials not only possess high surface areas and mesopores but also show good utilization of light energy. The ultraviolet-visible diffuse reflectance patterns of $Cd_xZn_{1-x}S@MIL-101$(Cr) nanocomposites showed that $Cd_{0.8}Zn_{0.2}S@MIL-101$(Cr) possessed good visible light response ability among the synthesized nanocomposites. The photocatalytic performance of the $Cd_xZn_{1-x}S@MIL-101$(Cr) nanocomposites were tested via degradation and mineralization of methylene blue in neutral water solution under light irradiation using a 300W xenon lamp. As a result, using $Cd_{0.8}Zn_{0.2}S@MIL-101$(Cr) as a catalyst, 99.2% of methylene blue was mineralized within 30 min. Due to the synergistic effect of adsorption by the MIL-101(Cr) component and photocatalytic degradation provided by the $Cd_{0.8}Zn_{0.2}S$ component, the $Cd_{0.8}Zn_{0.2}S@MIL-101$(Cr) catalyst displayed superior photocatalytic performance relative to $Cd_{0.8}Zn_{0.2}S$ and MIL-101(Cr). Furthermore, $Cd_{0.8}Zn_{0.2}S@MIL-101$(Cr) possessed excellent stability during photodegradation and exhibited good reusability. The remarkable photocatalytic performance of $Cd_{0.8}Zn_{0.2}S@MIL-101$(Cr) is likely due to the effective transfer of electrons and holes at the heterojunction interfaces.

Fabrication and Evaluation Hydrogenation Absorbing on Mg2NiHx-10 wt% CaF2 Composites (Mg2NiHx-10wt% CaF2 수소저장합금의 제조와 수소화 흡수평가)

  • YU, JE-SEON;HAN, JUNG-HUM;SIN, HYO-WON;HONG, TAE-WHAN
    • Journal of Hydrogen and New Energy
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    • v.31 no.6
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    • pp.553-557
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    • 2020
  • It is possible that hydrogen could replace coal and petroleum as the predominant energy source in the near future, but several challenges including cost, efficiency, and stability. Mg and Mg alloys are attractive hydrogen storage materials because of their lightweight and high absorption capacity. Their range of applications could be further extended if their hydrogenation properties could be improved. The main emphasis of this study was to investigate their hydrogenation properties for Synthesis of 10wt.% CaF2 in Mg2NiHx systems. The effect of BCR (66:1) and MA time (96 hours) on the hydrogenation properties of the composite was investigated. also, Mg2NiHx-10wt% CaF2 composites prepared by Mechanical Alloying are used in this work to illustrate the effect of catalysts on activation energy and kinetics of Magnesium hydride.

Optimization and Packed Bed Column Studies on Esterification of Glycerol to Synthesize Fuel Additives - Acetins

  • Britto, Pradima J;Kulkarni, Rajeswari M;Narula, Archna;Poonacha, Sunaina;Honnatagi, Rakshita;Shivanathan, Sneha;Wahab, Waasif
    • Korean Chemical Engineering Research
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    • v.60 no.1
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    • pp.70-79
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    • 2022
  • Biodiesel production has attracted attention as a sustainable source of fuel and is a competitive alternate to diesel engines. The glycerol that is produced as a by-product is generally discarded as waste and can be converted to green chemicals such as acetins to increase bio-diesel profitability. Acetins find application in fuel, food, pharmaceutical and leather industries. Batch experiments and analysis have been previously conducted for synthesis of acetins using glycerol esterification reaction aided by sulfated metal oxide catalysts (SO42-/CeO2-ZrO2). The aim of this study was to optimize process parameters: effects of mole ratio of reactants (glycerol and acetic acid), catalyst concentration and reaction temperature to maximize glycerol conversion/acetin selectivity. The optimum conditions for this reaction were determined using response surface methodology (RSM) designed as per a five-level-three-factor central composite design (CCD). Statistica software 10 was used to analyze the experimental data obtained. The optimized conditions obtained were molar ratio - 1:12, catalyst concentration - 6 wt.% and temperature -90 ℃. A packed bed reactor was fabricated and column studies were performed using the optimized conditions. The breakthrough curve was analyzed.

Hydrogen production using CdS-TiO2 composite photocatalysts (CdS-TiO2 복합 광촉매계에 의한 수소제조)

  • Kim, Soo-Sun;Jang, Jum-Suk;So, Won-Wook;Kim, Kwang-Je;Moon, Sang-Jin
    • Journal of Hydrogen and New Energy
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    • v.11 no.4
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    • pp.161-169
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    • 2000
  • In the case of photocatalytic hydrogen production from water, the performance-property relationships of CdS-TiO2 film type composite catalysts were investigated. To control the physical properties of the primary particles, the mixture of CdS and TiO2 nano-sols prepared by the sol-gel method at room temperature was hydrothermally treated at 240oC for 12hr. The film electrodes were prepared by the casting method. The photocurrents measured by a photoelectrochemical method and the hydrogen production rates measured by a photochemical method were closely dependent on the physical properties such as crystalline form, primary particle size and CdS/TiO2 mole ratio, and these varied in the range of 1.2~2.6 mA/cm2 and $1.0{\sim}1.6{\times}10-3mol/hr$, respectively.

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An Improved Manufacturing Method of p-Dicyclopentadiene (DCPD) using Tungsten Type Catalyst in Air Condition (대기 조건에서 경화가 가능한 텅스텐계 p-DCPD의 개선된 성형 방법)

  • Kwon, Dong-Jun;Shin, Pyeong-Su;Kim, Jong-Hyun;Park, Joung-Man
    • Composites Research
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    • v.29 no.4
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    • pp.216-222
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    • 2016
  • Ring-opening metathesis polymerization of p-dicyclopentadiene (DCPD) can be performed using the tungsten type catalyst. This reaction usually progresses in nitrogen condition, because the catalysts are extremely sensitive in air condition. To solve this problem, DCPD resin with tungsten (W) was cured using hot press after stirring of DCPD A and B liquid in air condition. Mechanical properties of DCPD were improved by reducing microvoid occurrence successfully by using hot press method. It might be because hot press could provide sufficient press on DCPD specimen. Addition of catalyst was not effective for the curing of resin in a short time. During polymerization, pressure and temperature had a great influence on the mechanical properties of DCPD.

Synthesis of Co3O4 Nanocubes as an Efficient Electrocatalysts for the Oxygen Evolution Reacitons (물 분해 과정에서 효율적인 촉매 특성을 보이는 Co3O4 nanocubes 합성)

  • Choi, Hyung Wook;Jeong, Dong In;Wu, Shengyuan;Kumar, Mohit;Kang, Bong Kyun;Yang, Woo Seok;Yoon, Dae Ho
    • Composites Research
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    • v.32 no.6
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    • pp.355-359
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    • 2019
  • The high efficient water splitting system should involve the reduction of high overpotential value, which was enhanced by the electrocatalytic reaction efficiency of catalysts, during the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) reaction, respectively. Among them, transition metal-based compounds (oxides, sulfides, phosphides, and nitrides) are attracting attention as catalyst materials to replace noble metals that are currently commercially available. Herein, we synthesized optimal monodisperse Co3[Co(CN)6]2 PBAs by FESEM, and confirmed crystallinity by XRD and FT-IR, and thermal behavior of PBAs via TG-DTA. Also, we synthesized monodispersed Co3O4 nanocubes by calcination of Co3[Co(CN)6]2 PBAs, confirmed the crystallinity by XRD, and proceeded OER measurement. Finally, the synthesized Co3O4 nanocubes showed a low overpotential of 312 mV at a current density of 10 mA·cm-2 with a low Tafel plot (96.6 mV·dec-1).

Characteristics of CL-SPEEK/HPA Membrane Electrodes with Pt-Ni and Pt-Co Electrocatalysts for Water Electrolysis (전극 촉매 Pt-Ni 및 Pt-Co를 이용한 수전해용 공유가교 CL-SPEEK/HPA 막전극의 특성)

  • Woo, Je-Young;Lee, Kwang-Mun;Jee, Bong-Chul;Chung, Jang-Hoon;Moon, Sang-Bong;Kang, An-Soo
    • Journal of Hydrogen and New Energy
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    • v.21 no.1
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    • pp.26-34
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    • 2010
  • The electrocatalystic prperties of Pt-Co and Pt-Ni with heteropolyacids (HPAs) entrapped in covalently cross-linked sulfonated poly(ether ether ketone) (CL-SPEEK)/HPA membranes were investigated for water electrolysis. The HP As, including molybdophosphoric acid (MoPA), and tungstophosphoric acid (TPA) were both used as membrane additives and electrocatalysts. The membrane electrode assembly (MEA) was prepared by a nonequilibrium impregnation-reduction (I-R) method. $Pt(NH_3)_4Cl_2$, $NiCl_2$ and $CoCl_2$ as electrocatalytic materials and $NaBH_4$ as reducing agent were used. I order to enhance electrocatalytic activity, the catalyst layer prepared above was electrodeposited (Dep) with HP A. Surface morphologies and physico-chemical properties of MEA were investigated by means of SEM, EDX and XRD. The electrocatalytic properties of composite membranes such as the cell voltage and coulombic charge in CV were in the order of magnitude: CL-SPEEK/MoPA40 (wt%) > CL-SPEEK/TPA30 > Nafion117. In the optimum cell applications for water electrolysis, the cell voltage of Pt/CL-SPEEK-MoPA40/Pt-Co (Dep-MoPA) and Pt/CL-SPEEK-TPA30/Pt-Co (Dep-TPA) was 1.75 Vat $80^{\circ}C$ and $1\;A/cm^2$ and voltage efficiency was 87.1%. Also, the observed activity of Pt-Co (84:16 atomic ratio by EDX) is a little higher than that of Pt-Ni (86: 14). The current density peak of electrodeposited electrodes were better a little than those of unactivated electrodes based on the same membranes.

Immobilization of Homogeneous Catalyst on Functionalized Carbon Nanotube via 1,3-Dipolar Cycloaddition Reaction and its Ethylene Polymerization (1,3-Dipolar cycloaddition 반응을 통해 기능화된 carbon nanotube 표면 위에 균일계 촉매 담지 및 에틸렌 중합)

  • Lee, Jeong Suk;Lee, Se Young;Lee, Jin Woo;Ko, Young Soo
    • Korean Chemical Engineering Research
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    • v.54 no.4
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    • pp.574-581
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    • 2016
  • In this study, CNT functionalized with pyrrolidine ring via 1,3-dipolar cycloaddition reaction with various amino acid and aldehyde was synthesized. Metallocene was subsequently immobilized on the functionalized CNT and CNT/polyethylene composite was prepared via in-situ ethylene polymerization. The polymerization activities of metallocene supported on CNT functionalized with glycine and benzaldehyde (Gly+BA-CNT) were similar to those of metallocene supported on CNT functionalized with N-benzyloxycarbonylglycine and paraformaldehyde (Z-Gly+PFA-CNT) although its Zr content was lower than that of Z-Gly+PFA-CNT. In the case of metallocene supported on Z-Gly+PFA-CNT, the even distribution of active sites hindered the diffusion of ethylene monomer and cocatalyst MAO due to steric hindrance during ethylene polymerization. Compared to polyethylene produced from homogeneous metallocene catalysts, CNT/PE composites had a higher initial degradation temperature ($T_{onset}$) and maximum mass loss temperature ($T_{max}$). It suggests that pyrrolidine functionalized CNT is uniformly dispersed and strongly interacted with the PE matrix, enhancing the thermal stability of PE.