• Title/Summary/Keyword: 4A zeolite

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The Effect of Pore Structure of Zeolites on their Product Distribution and Deactivation in the Catalytic Cracking of n-Octane (n-옥탄의 촉매 분해반응에서 제올라이트의 세공구조가 생성물 분포와 활성저하에 미치는 영향)

  • Min, Byung Goo;Lee, Jae Youl;Song, Yo Soon;Seo, Gon
    • Korean Chemical Engineering Research
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    • v.45 no.6
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    • pp.547-553
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    • 2007
  • The catalytic cracking of n-octane over FER, MFI, MOR and BEA zeolites was studied by the protolytic cracking mechanism in order to understand the effect of pore structure of zeolites on their product composition and deactivation. The selectivities for $C_3$ and $C_3{^=}$ were high over the zeolites with medium pores due to additional cracking, while those for $C_4$ and $C_4{^=}$, the initial products, were high over the zeolites with large pores. MFI zeolite showed slow deactivation due to small carbon deposit, while FER zeolite with small pores deactivated rapidly with severe carbon deposit. The deactivation of BEA zeolite was slow even with a large amount of carbon deposit, but MOR zeolite showed a rapid deactivation even with a small amount of carbon deposit. The conversion measured along with the time on stream on these zeolite catalysts was simulated by a mechanism based on the simplified reaction path of n-octane cracking and the deactivation related to the pore blockage by carbon deposit.

Influence of Continious Application of Gypsum, Popped Rice Hull, and Zeolite on Soil Aggregation of Reclaimed Sandy Loam Soils (석고, 팽화왕겨 및 제오라이트 연속시용이 간척지 세사양토의 입단화에 미치는 영향)

  • Baek, Seung-Hwa;Kim, Jae-Young;Lee, Sang-Uk;Kim, Seong-Jo
    • Korean Journal of Soil Science and Fertilizer
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    • v.43 no.5
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    • pp.764-769
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    • 2010
  • We investigated influence of continious application of gypsum (G: $CaSO_4{\cdot}2H_2O$), popped rice hulls (H) and zeolite (Z) on soil aggregation of reclaimed sandy loam soils. The application rates amended to fine sandy loam from reclaimed soils at Kyehwado were varied as follows:1550 (G1), 3100 (G2), 6200 (G3), 1000 (H1), 2000 (H2), 3000 (H3), and 200 (HZ1), 400 (HZ2) and 800 (HZ3) added to 1500(H) kg $10a^{-1}$, respectively. Soil aggregates were analyzed for 60, 90 and 120 days after treatments (DAT). At 60 DAT, The amount of aggregate from soil samples treated with gypsum was slightly increased with G1 while the aggregation was decreased by 4.66% for G3 for soil aggregates than thar of control. The treatments of H or HZ were effective in soil aggregation. The effect of treatment was in the order of H > HZ > G. At 90 DAT, increasing amount of gypsum attributed to decrease in soil aggregates. Therefore, we could conclude that suitable amounts of gypsum for soil aggregation in fine sandy loam might be 1550 kg $10a^{-1}$ or less. H1 increased aggregation by 7% for aggregate size between 1.0 and 2.0 mm. HZ1 was most effective in aggregation by 52.78% among the treatments while H2 and HZ3 51.50% and 48.51% at 120 DAT, respectively. As a result, we found that the effect of the treatment for soil amendments was in order of H > HZ > G.

Effects of Zeolite Application on Yield and Yield Components in Rice (Zeolite 시용에 의한 벼의 증수효과 및 요인해석)

  • Kae, Bong-Myung;Sol, Kwon-Sok;Cho, Chang-Hwan
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.32 no.4
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    • pp.403-408
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    • 1987
  • The milled rice yield of the fertilized Zeolite in the sandy loam as 542 Kg/10a was increased by 11% compared with the check plat as a standard cultivation. Significant positive correlations of that were found between grain yield/plant and panicle/total weight ratio or average weight of panicle, while lower correlations between ratio of riqened grains and grain yield/ plant. But significant negative correlations were found between 1,000-grain weight of rough and 4th. 5th internode/culm length ratio. It was reavealed that there were higher direct effects for ratio of ripened grains and spikelets/panicle affecting grain yield/plant through path analysis among the yield components. Moreover, organic dry matter production at 35 days after heading were heavier by 26% in active leaves, 19% in stem + leaf sheath, and 5% in panicle, respectively. Ratio of settled spikelets on the terminal of primary rachis-branch was 47% to total spikelets, and 37% in half-upper of that, moreover many spikelets settled on the terminal of rachis. Therefore, it was recognized that there were a dominant effect of apical glumous flower by fertilized Zeolite.

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Synthesis of P-type Zeolite Using Melting Slag from Municipal Incineration Ash (도시 소각재 용융슬래그로부터 P형 제올라이트 합성)

  • Lee Sung-Ki;Jang Young-Nam;Chae Soo-Chun;Ryu Kyoung-Won;Bae In-Kook
    • Journal of the Mineralogical Society of Korea
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    • v.19 no.1 s.47
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    • pp.7-14
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    • 2006
  • Melting slag generated from the lots of municipal incineration ash, which causes the one of big urban problems in modern industrial society, was used as starting material for the hydrothermal synthesis of zeolite. P-type zeolite has been successfully synthesized by the combined process of both 'hydrogelation' and 'clay conversion' method. Commercial sodium silicate was used as Si source, and $NaAlO_2$ was prepared by the reaction in a $Na_{2}O/Al_{2}O_{3}$ molar ratio of 1.2. The optimum conditions for zeolite synthesis was found to be the $SiO_{2}/Al_{2}O_{3}$ ratio in the 3.2 and 4.2 range, the $H_{2}O/Na_{2}O$ ratio in the 70.7 and 80.0 range, and more than 15-hour reaction time at $80^{\circ}C$, In the synthesized zeolite, inhomogeneous melting slag particles were disappeared and homogeneous P-type zeolite crystal was grown. The cation exchange capacity of the synthesized zeolite was determined to be approx. 240 cmol/kg.

A Study on Dealumination of NaY Zeolite and its VOCs Adsorption Properties (Dealumination에 의한 NaY zeolite의 개질과 VOCs 흡착특성에 관한 연구)

  • Kang, Shinchoon;Lee, Hwayeol;Park, Yeungho
    • Korean Chemical Engineering Research
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    • v.53 no.3
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    • pp.339-349
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    • 2015
  • In this work, DAY (Dealuminated Y-type) zeolites were prepared to be used as easily regenerable and thermally stable adsorbent substituting activated carbon. NaY zeolites were transformed into DAY zeolites through ion exchange, calcination, steaming, and acid leaching. Calcination temperature and time, and steaming time were changed to increase the Si/Al ratio and maintain crystallinity. Adsorption of VOCs were done for prepared DAY, commercial NaY and Hisiv 1000 in air with relative humidity of 50%. The DAY zeolite prepared by calcination at $520^{\circ}C$ for 4 hrs and steaming for 7 hrs had a same structure and a Si/Al ratio of 80.4. Its adsorption capacity for water vapor was 10% of NaY, indicating its hydrophobicity. Its adsorption capacity for MEK was 0.8 times of Hisiv 1000, that for toluene 1.6 times, and that for EA 1.3 times.

Study of nitrate concentration in Najaf Abad aquifer using GIS

  • Tabatabaei, Javad;Gorji, Leila
    • Membrane and Water Treatment
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    • v.11 no.2
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    • pp.167-172
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    • 2020
  • The effectiveness of in situ sediment capping as a technique for heavy metal risk mitigation in Hyeongsan River estuary, South Korea was studied. Sites in the estuary were found previously to show moderate to high levels of contamination of mercury, methylmercury and other heavy metals. A 400 m x 50 m section of the river was selected for a thin layer capping demonstration, where the total area was divided into 4 sections capped with different combinations of capping materials (zeolite, AC/zeolite, AC/sand, zeolite/sand). Pore water concentrations in the different sites were studied using diffusive gradient in thin film (DGT) probes. All capping amendments showed reduction in the pore water concentration of the different heavy metals with top 5 cm showing %reduction greater than 90% for some heavy metals. The relative maxima for the different metals were found to be translated to lower depths with addition of the caps. For two-layered cap with AC, order of placement should be considered since AC can easily be displaced due to its relatively low density. Investigation of methylmercury (MeHg) in the site showed that MeHg and %MeHg in pore water corresponds well with maxima for sulfide, Fe and Mn suggesting mercury methylation as probably coupled with sulfate, Fe and Mn reduction in sediments. Our results showed that thin-layer capping of active sorbents AC and zeolite, in combination with passive sand caps, are potential remediation strategy for sediments contaminated with heavy metals.

Effects of Operating Conditions on Adsorption and Desorption of Benzene in TSA Process Using Activated Carbon and Zeolite 13X (활성탄과 제올라이트 13X 충진탑을 사용한 TSA 공정에서 조업조건이 벤젠의 흡착 및 탈착에 미치는 영향)

  • Jung, Min-Young;Suh, Sung-Sup
    • Applied Chemistry for Engineering
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    • v.29 no.5
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    • pp.594-603
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    • 2018
  • The effects of operating conditions such as benzene concentration, nitrogen flow rate, steam flow rate, and bed temperature on TSA process were experimentally investigated as a potential VOC removal technology using two kinds of beds packed with activated carbon and zeolite 13X. The TSA cycle studied was composed of the adsorption step, steam desorption step, and drying and cooling step. At 2% benzene concentration, the total adsorption amounts of zeolite 13X and activated carbon were 4.44 g and 3.65 g, respectively. Since the zeolite 13X has a larger packing density than that of the activated carbon, the larger benzene amount could be adsorbed in a single cycle. Increasing the water vapor flow rate to 75 g/hr at 2% benzene concentration reduced the desorption time from 1 hr to a maximum of 33 min. If the desorption time is shortened, the drying and cooling step period can be relatively increased. Accordingly, the steam removal and bed cooling could be sufficiently performed. The desorption amounts increased with the increase of the bed temperature. However, the energy consumption increased while the desorption amount was almost constant above $150^{\circ}C$. In the continuous cycle process, when the amount of remained benzene at the completion of the regeneration step increased, it might cause a decrease in the working capacity of the adsorbent. The continuous cycle process experiment for zeolite 13X showed that the amount of remained benzene at the end of regeneration step maintained a constant value after the fourth cycle.

A Study on the Hydrated and Dehydrated $Mn^{2+}$-Exchanged Zeolite A ($Mn^{2+}$-치환 제올라이트 A 의 수화 및 탈수 구조에 관한 연구)

  • Jong Yul Park;Yang Kim;Un Sik Kim;Sang Gu Choi
    • Journal of the Korean Chemical Society
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    • v.33 no.6
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    • pp.623-632
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    • 1989
  • The positions and interaction energies of framework atoms and water molecules of $Mn^{2+}$-exchanged zeolite A were calculated using some potential energy functions and an optimization program. The sum of interaction energies of framework atoms in dehydrated $Mn_{4,5}Na_3-A$ was approximately the same as those of thermally stable $Ca^{2+}$-or $Mg^{2+}$-exchanged zeolite A. Since $Mn^{2+}$ ions can form good coordination bonds with framework oxygens even in dehydrated state, $Mn^{2+}$-exchanged zeolite A is considered to be thermally stable. The optimized positions of framework atoms and ions in this work are agreed well with the crystallographic data. Three groups of water molecules are found in hydrated $Mn^{2+}$-exchanged zeolite A; W(I) group of water molecules having only hydrogen bonds, W(II) group coordinated to $Na^+$ ion, and W(III) group coordinated to $Mn^{2+}$ ion. The average binding energy of each group of water molecules decrease in the order of W(III) > W(II) > W(I). The activation energies in the dehydration reaction of each group of water molecules increased in accordance with their binding energy.

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Recovery of nitrogen from high strength waste stream by using natural zeolite (Clinoptilolite) (천연 제올라이트를 이용한 고농도 질소 회수)

  • Choi, Oh Kyung;Lee, Kwanhyoung;Dong, Dandan;Lee, Jaewoo
    • Journal of Korean Society of Water and Wastewater
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    • v.30 no.1
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    • pp.105-111
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    • 2016
  • This paper presents the applicability of natural zeolite (Clinoptilolite) for recovery of ammonium nitrogen from high-strength wastewater stream. Isotherm experiments showed the ammonium exchange Clinoptilolite followed Freundlich isotherm and its maximum exchange capacity was $18.13mg\;NH_4{^+}-N/g$ zeolite. The X-ray photoelectron spectroscopy (XPS) analysis indicated that a significant amount of nitrogen was adsorbed to the Clinoptilolite. Optimal flowrate for recovery of high concentration ammonium nitrogen was determined at 16 BV/d (=19.2 L/min) throughout the lab-scale column studies operated under various flowrate conditions. This study also provided a method to determine the recovery rate of final product of nitrogen fertilizer based on the model application to the lab-scale continuous data.

Heavy Metal Wastewater Treatment (Batch Mode) by Domestic Zeolite (국산(國産) Zeolite를 이용(利用)한 중금속(重金屬) 폐수(廢水) 처리공정(處理工程) 연구(硏究) - Batch Test를 중심(中心)으로 -)

  • Shin, Eung Bai
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.2 no.1
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    • pp.63-68
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    • 1982
  • This study was aimed ultimately to develop an adsorption process treating heavy metal industrial wastewater by utilizing domestically abundant natural zeolite and the study was conducted in a series of investigations. Presented if1 this paper are the results of the preliminary batch mode test. Factors affecting an adsorption process of heavy metals of aqueous waste stream by zeolite are numerous. Factors such as hydrogen ion concentration and temperature are taken into consideration in the investigation to evaluate adsorptive capacity. The mechanisms of adsorption may better be described by an evaluation of adsorption isotherm andi of adsorption kinetics. It is observed from the preliminary investigation that an optimum adsorption occurs at higher pH's than 4. It is further demonstrated that $Cd^{+2}$ adsorption by zeolite follows the BET model better than the Freundlich and the Langmuir model and that the reaction time of at least 10 minutes is required. It is interesting to note that higher adsorptive capacity was found at higher temperature, suggesting that the adsorption is not only due to simple physisorption but also due to chemisorption.

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