• Title/Summary/Keyword: H-ZSM-5

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Investigation of influence of nano H-ZSM-5 and NH4-ZSM-5 zeolites on membrane fouling in semi batch MBR

  • Sajadian, Zahra Sadat;Hazrati, Hossein;Rostamizadeh, Mohammad
    • Advances in nano research
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    • v.8 no.2
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    • pp.183-190
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    • 2020
  • The objectives of this research were the reduction of membrane fouling and improvement of sludge properties by using synthesized H-ZSM-5 and NH4-ZSM-5 zeolites. These two nano zeolites were synthesized and added to the membrane bioreactor (MBR). Three similar MBRs with the same operational condition were used in order to evaluate their effect on the mentioned matters. The evaluated parameters were trans-membrane pressure (TMP), Fourier-transform infrared spectroscopy (FTIR), particle size distribution (PSD), soluble microbial product (SMP), extracellular polymeric substances (EPS) and, excitation-emission matrix (EEM). The MBR0 was without any additional zeolite while 0.4 g/L of H-ZSM-5 and NH4-ZSM-5 were added to MBRHZSM-5 and MBRNH4ZSM-5, respectively. The COD removal of the MBR0, MBRH-ZSM-5 and MBRNH4-ZSM-5 were 87.5%, 93.3% and 94.6%, respectively. The TMP of the MBRH-ZSM-5 was 45% less than MBR0 whereas the reduction for MBRNH4-ZSM-5 was 65.5%. Also results showed that both H-ZSM-5 and NH4-ZSM-5 caused reduction in protein and polysaccharide related EPS but the NH4-ZSM-5 had better performance toward the elimination of organic compounds.

Effect of Temperature on Propylene Aromatization over MFI Type Zeolites (Propylene Aromatization에 미치는 온도 및 촉매의 영향)

  • Park, Jin-U;Kim, Sang-Bum;Kwak, Yun-Cheol;Shin, Ki-Seok;Park, Hong-Soo;Hahm, Hyun-Sik
    • Journal of the Korean Applied Science and Technology
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    • v.19 no.2
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    • pp.123-130
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    • 2002
  • [Ga]-MFI and H-ZSM-5 catalysts were synthesized under atmospheric pressure and used in the propylene aromatization. The effect of temperature on the product distribution was also investigated. The catalytic activities of the prepared catalysts were compared with the commercialized H-ZSM-5 which was converted from $NH_{4}$-ZSM-5. In the propylene aromatization, product distribution does not depend on the ratio of Si/$Ga_{2}$ with [Ga]-MFI catalyst, but depend on the ratio of Si/$Al_{2}$ with H-ZSM-5 catalyst [Ga]-MFI catalyst shows better dehydrogenation and alkylation activities than H-ZSM-5 catalyst The addition of Ga to H-ZSM-5 catalyst increases the conversion of propylene, selectivity to aromatics, and alkylation. In the propylene aromatization, the selectivity to aromatics slightly increased with increasing temperature with [Ga]-MFI catalyst, while slightly decreased with increasing temperature with H-ZSM-5 catalyst.

Dehydration of Methanol to Dimethyl Ether over ZSM-5 Zeolite

  • Jiang, Shan;Hwang, Jin-Soo;Jin, Tai-Huan;Cai, Tianxi;Cho, Wonihl;Baek, Young-Soon;Park, Sang-Eon
    • Bulletin of the Korean Chemical Society
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    • v.25 no.2
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    • pp.185-189
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    • 2004
  • Methanol dehydration to dimethyl ether (DME) has been investigated over ZSM-5 zeolites and compared with that of ${\gamma}-Al_2O_3$. Although the catalytic activity was decreased with an increase in silica/alumina ratio, the DME selectivity increased. H-ZSM-5 and NaH-ZSM-5 zeolites were more active for conversion of methanol to DME than ${\gamma}-Al_2O_3$. $Na^+$ ion-exchanged H-ZSM-5 (NaH-ZSM-5) shows higher DME selectivity than H-ZSM-5 due to the selective removal of strong acid sites.

Esterification of Methacrylic acid with Ethylene glycol over Heteropolyacid supported on ZSM-5 (ZSM-5 위에 지지된 Heteropolyacid 하에서 Methacrylic acid와 Ethylene glycol의 에스테르화 반응)

  • Prabhakarn, A.;Fereiro, J.A.;Subrahmanyam, Ch.
    • Journal of the Korean Chemical Society
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    • v.55 no.1
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    • pp.14-18
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    • 2011
  • Esterification of methacrylic acid with ethylene glycol was carried out over Heteropolyacids [HPA: $H_4SiW_{12}O_{40}$ (STA) and $H_3PW_{12}O_{40}$ (PTA)] supported on ZSM-5. For comparison, the same reaction was carried out over unsupported HPA, $H_2SO_4$, $BF_3$ and PTSA. Among the catalysts studied, HPA showed better activity compared to $H_2SO_4$, $BF_3$ and PTSA. Catalytic activity was compared with HPA supported ZSM-5 catalysts. Typical results indicated that 30 wt% PTA supported on ZSM-5 showed nearly the same activity as that of bulk PTA. It was found that the reaction follows first order kinetics with respect to methacrylic acid. The reaction products were identified by $^1H$-NMR and FT-IR.

Diffusion Controlled Alkylation of Aromatic Compounds in Cation-Exchanged ZSM-5 Zeolites

  • Chon, Hak-Ze;Lee, Kyung-Yul;Park, Dong-Ho;Ahn, Byoung-Joon
    • Bulletin of the Korean Chemical Society
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    • v.12 no.6
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    • pp.625-628
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    • 1991
  • Using uniform flat plate-like samples of ZSM-5 zeolites, diffusion coefficients were measured volumetrically for the diffusion of xylene, ethyltoluene and diethylbenzene by direct measurement of sorption rate. Toluene disproportionation over H(100)-, K(72)-and Cs(82)-ZSM-5 at 773 K and toluene methylation, toluene ethylation and ethylbenzene ethylation over Cs(75)-ZSM-5 at 623 K were carried out. The selective formation of para xylene during the toluene disproportionation, presumably due to the increased tortuosity over Cs-ZSM-5, could be explained by smaller diffusion coefficient in Cs-ZSM-5 than in K-and H-ZSM-5. The para selectivity increased in the order; toluene methylation < toluene ethylation < ethylbenzene ethylation. As the chain length of the alkyl substituent in dialkylbenzenes is increased, the para selectivity of the products was improved. It may be attributed to the differences in the ratios of diffusion coefficient of para products to that of ortho ones. Diffusion coefficient of m-xylene was about 1 order of magnitude smaller than that of o-xylene.

Selective Catalytic Reduction of Nitric Oxide over Metal Exchanged ZSM-5 Catalysts (금속을 이온교환시킨 ZSM-5 촉매 상에서 Nitric Oxide의 환원반응)

  • Ahn, Sung-Hwan;Kim, Tae-Ok;Hahm, Hyun-Sik
    • Journal of the Korean Applied Science and Technology
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    • v.17 no.1
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    • pp.1-5
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    • 2000
  • The selective catalytic reduction(SCR) of nitric oxide by ethane in the presence of oxygen was investigated on Cu-ZSM-5, Co-ZSM-5 and Ga-ZSM-5 catalysts over a range of 400, 450 and $500^{\circ}C$. The catalysts were prepared by ion-exchange method. The composition of the reactant gases were 1000 ppm of NO, 1000 ppm of $C_{2}H_{6}$ and 2.5% of $O_{2}$, and the reaction was conducted in a fixed-bed reactor at 1 atm. For the 20wt% Co-ZSM-5(50) catalyst, the NO conversion reached up to 100%, while the $C_2H_6$ conversion and the CO selectivity were about 50% and 25%, respectively, at $450^{\circ}C$. For the 20wt% Cu-ZSM-5(50) catalyst, the NO conversion and the C2H6 conversion were about 80% and 100%, respectively, but there was no CO produced. The metal ion-exchanged ZSM-5 catalysts exhibited a tendency to increase the NO conversion with the Si/Al ratio of the ZSM-5, that is, NO conversion was inversely proportional to the acidity of the catalysts. But, the effect of the acidity on NO conversion was not so large. From the XRD results of the catalysts before and after SCR reaction it was found that there was no structural change.

Catalytic Cracking of n-Octane over H-ZSM-5 Catalysts: Effect of Calcination and Steam Treatment (H-ZSM-5 촉매에서 n-옥탄의 촉매분해반응: 소성 및 스팀 처리 효과)

  • Lee, Hyun-Ju;Shin, Chae-Ho;Choi, Won Choon;Lee, Chul Wee;Park, Yong Ki
    • Korean Chemical Engineering Research
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    • v.46 no.2
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    • pp.291-300
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    • 2008
  • Catalytic cracking of n-octane was carried out over H-ZSM-5 zeolite catalysts after calcination with air and steaming with 100% steam in the temperature range of $550-750^{\circ}C$ for 24 h and compared with the results of thermal cracking. The increase of calcination and steaming temperature resulted in the decrease of surface area, pore volume, and strong acid sites, which was mainly caused by the dealumination of H-ZSM-5 framework. It was found by $^{27}Al$ and $^{29}Si$ MAS NMR that the dealumination was proceeded through the transformation process of tetrahedral framework Al${\rightarrow}$penta-cordinated Al ${\rightarrow}$ octahedral framework Al and the phenomena was much more severe in steaming conditions than that of calcination. In the catalytic cracking of n-octane, as the temperatures of calcination and steaming were increased, the conversion of n-octane, the selectivity of light olefins and ethylene to propylene ratio were decreased due to the dealumination of framework aluminum resulting the loss of acidic strengths. The conversion, selectivity of light olefins and ethylene to propylene ratio reached almost to the level of thermal cracking after steaming at $750^{\circ}C$ for 24 h.

Modification of H-ZSM-5 and γ-Alumina with Formaldehyde and Its Application to the Synthesis of Dimethyl Ether from Syn-gas

  • Joo, Oh-Shim;Jung, Kwang-Deog;Han, Sung-Hwan
    • Bulletin of the Korean Chemical Society
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    • v.23 no.8
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    • pp.1103-1105
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    • 2002
  • H-ZSM-5 and γ-alumina were treated with formaldehyde and sodium carbonate. The treatment increased the amounts of weak acid sites, removing strong acid sites. The maximum temperature of weak acid sites in their ammonia TPD spectra shifted in the direction of high temperature. The modified H-ZSM-5 and g-alumina were mixed with the methanol synthesis catalyst to perform dimethyl ether synthesis from syn-gas. The modified catalysts showed better selectivity to dimethyl ether, minimizing the reforming reaction to carbon dioxide. The maximum yield of 53.3% to dimethyl ether was achieved under the reaction conditions of 54.4 atm, 523 K, and the feed rate of 4500 Lhr-1 .gcat-1.

Transesterification of Jatropha Oil over Ceria-Impregnated ZSM-5 for the Production of Bio-Diesel

  • Bhagiyalakshmi, Margandan;Vinoba, Mari;Grace, Andrews Nirmala
    • Bulletin of the Korean Chemical Society
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    • v.34 no.10
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    • pp.3059-3064
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    • 2013
  • In this study transesterification of Triglycerides (TG) from Jatropha curcas oil (JCO) with methanol for production of biodiesel was investigated over cerium impregnated ZSM-5 catalysts. NaZSM-5 was synthesized in an alkaline medium and impregnated with cerium oxide by wet method using cerium nitrate as a source for cerium. They were characterized by X-ray diffraction (XRD), Thermogravimeteric analysis (TGA), $CO_2$-temperature programmed desorption, and $N_2$ adsorption/desorption analysis. XRD analysis showed decrease in intensity of the patterns with the increase in the ceria loading but crystallization of ceria to larger size is an evident for 10 and 15% loading. The optimal yield of transesterification process was found to be 90% under the following conditions: oil to methanol molar ratio: 1:12; temperature: $60^{\circ}C$; time: 1 h; catalyst: 5 wt %. Here the yield of fatty acid methyl ester (FAME) was calculated through $^1H$ NMR analysis. The investigation on catalyst loading, temperature, time and reusability illustrated that these ceria impregnated NaZSM-5's were found to be selective, recyclable and could yield biodiesel at low temperature with low methanol to oil ratio due to the presence of both Lewis and Bronsted basicity. Hence, from the above study it is concluded that ceria impregnated ZSM-5 could be recognized as a potential catalysts for biodiesel production in industrial processes.

A Study on Optimization of Alumina and Catalysts Coating on Tube Reactor for Endothermic Reaction of n-Dodecane Under Supercritical Conditions (고온, 고압 조건에서 n-dodecane 액체연료의 흡열분해를 위한 관벽 내 알루미나 및 촉매 코팅 최적화 연구)

  • Kim, Sung Su;Lee, Sang Moon;Lee, Ye Hwan;Lee, Dong Yoon;Gwak, Ji-Yeong
    • Journal of the Korean Society of Propulsion Engineers
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    • v.25 no.3
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    • pp.56-61
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    • 2021
  • In this study, Al2O3 and H-ZSM-5 were coated on the inner wall of the stainless steel tube for the stable use of liquid hydrocarbon fuel and an endothermic catalyst used as coolant for hypersonic flying vehicles. Coke production is inevitable by the endothermic decomposition reaction of the liquid hydrocarbon fuel, and Fe, Ni metals induce the production of the filamentous coke by using a stainless steel tube reactor as a cooling channel. By coating the stainless steel with H-ZSM-5, Fe and Ni metals are prevented from being directly exposed to the liquid hydrocarbon fuel, and the formation of the filamentous coke is inhibited. In addition, Al2O3 is coated between the stainless steel and H-ZSM-5 to enhance adhesion bond strength.