• Title/Summary/Keyword: 압력전달매개체

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Phase Transition of Zeolite X under High Pressure and Temperature (고온 고압 환경에서 합성 제올라이트 X의 상전이 비교연구)

  • Hyunseung Lee;Soojin Lee;Yongmoon Lee
    • Economic and Environmental Geology
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    • v.56 no.1
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    • pp.13-21
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    • 2023
  • X-ray powder diffraction study was conducted on the bulk modulus and phase transition behavior of synthetic zeolite X under high temperature and high pressure. Water and HCO3- solution were used as a PTM. Sample was heated and pressurized up to 250 ℃ and 5.18 GPa. The change of unit cell volume and phase transition were observed by X-ray diffraction. The lattice constants and unit cell volume of zeolite X, gmelinite, natrolite, and smectite were calculated using the GSAS2 program to which Le Bail's whole powder pattern decomposition (WPPD) method was applied. The bulk modulus of each zeolite X and smectite were calculated using the EosFit program to which the Birch-Murnaghan equation was applied. The bulk modulus of zeolite X is 89(3) GPa in water run, and zeolite X is 92(3) GPa in HCO3- solution run. In both run, pressure induced hydration (PIH) occurred due to the inflow of PTM into the zeolite X framework at initial pressure. Zeolite X transited to gmelinite, natrolite, and smectite in water run. Zeolite X, however, transited to smectite in HCO3- solution run. Interzeolite transformation occurred in water run, and did not occur in HCO3- solution run, which is assumed that conflict between the environment to form zeolite and the pH of the HCO3- solution.

Changes in the Linear Compressibility and Bulk Modulus of Natural Stilbite Under Pressure with Varying Pressure-Transmitting Media (천연 스틸바이트의 압력전달매개체에 따른 선형압축률 및 체적탄성률 비교 연구)

  • Hwang, Huijeong;Lee, Hyunseung;Lee, Soojin;Jung, Jaewoo;Lee, Yongmoon
    • Korean Journal of Mineralogy and Petrology
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    • v.35 no.3
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    • pp.367-376
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    • 2022
  • This study is a preliminary step to understand the reaction between various liquids and zeolite in the subduction zone environment. Stilbite, NaCa4(Al9Si27)O72·28(H2O), was selected and high pressure study was conducted on compressional behavior by the pressure-transmitting medium (PTM). Water and NaHCO3 solution that can exist in the subduction zone was used as PTM, and samples were pressurized from ambient to a maximum of 2.5 GPa. Below 1.0 GPa, both experiments show a low linear compressibility in the range of 0.001 to 0.004 GPa-1 and a high bulk modulus of 220(1) GPa. This is presumably because the structure of the stilbite becomes very dense due to insertion of water molecules or cations into the channel. On the other hand, at 1.0 GPa or higher, the trends of the two experiments are different. In the water run, the linear compressibility of the c-axis is increased to 0.006(1) GPa-1. In the NaHCO3 run, the linear compressibility of the b- and c-axis is increased to 0.006(1) GPa-1. The bulk modulus after 1.0 GPa shows values of 40(1) and 52(7) GPa in water and NaHCO3 run, respectively, confirming that stilbite becomes more compressible than that before 1.0 GPa. It is caused by the migration of cations and water molecules inside the channel, as the water molecules in the PTM start to freeze and stop to insert toward the channel at 1.0 GPa or more. In the NaHCO3 run, it is assumed that the distribution of extra-framework species inside the structure is changed by substitution of the Na+ cation. It can be expected from tendency of the relative intensity ratio of the (001) and (020) peaks which show a different from that of the water run.

Comparative Compressional Behavior of Zeolite-W in Different Pressure-transmitting Media (제올라이트-W의 압력전달매개체에 따른 체적탄성률 비교 연구)

  • Seoung, Donghoon;Kim, Hyeonsu;Kim, Pyosang;Lee, Yongmoon
    • Korean Journal of Mineralogy and Petrology
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    • v.34 no.3
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    • pp.169-176
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    • 2021
  • This study aimed to fundamentally understand structural changes of zeolite under pressure and in the presence of different pressure-transmitting media (PTM) for application studies such as immobilization of heavy metal cation or CO2 storage using pressure. High-pressure X-ray powder diffraction study was conducted on the zeolite-W (K6.4Al6.5Si25.8O64× 15.3H2O, K-MER) to understand linear compressibility and the bulk moduli in different PTM conditions. Zeolite-w is a synthetic material having the same framework as natural zeolite merlinoite ((K, Ca0.5, Ba0.5, Na)10 Al10Si22O64× 22H2O). The space group of the sample was identified as I4/mmm belonging to the tetragonal crystal system. Water, carbon dioxide, and silicone-oil were used as pressure-transmitting media. The mixture of sample and each PTM was mounted in a diamond anvil cell (DAC) and then pressurized up to 3 GPa with an increment of ca. 0.5 GPa. Pressure-induced changes of powder diffraction patterns were measured using a synchrotron X-ray light source. Lattice constants, and bulk moduli were calculated using the Le-Bail method and the Birch-Murnaghan equation. In all PTM conditions, linear compressibility of c-axis (𝛽c) was 0.006(1) GPa-1 or 0.007(1) GPa-1. On the other hand, the linear compressibility of a(b)-axis (𝛽a) was 0.013(1) GPa-1 in silicone-oil run, which is twice more compressible than the a(b)-axis in water and carbon dioxide runs, 𝛽a = 0.006(1) GPa-1. The bulk moduli were measured as 50(3) GPa, 52(3) GPa, and 29(2) GPa in water, carbon dioxide, and silicone-oil run, respectively. The orthorhombicities of ac-plane in the water, and carbon dioxide runs were comparatively constant, near 0.350~0.353, whereas the value decreased abruptly in the silicone-oil run following formula, y = -0.005(1)x + 0.351(1) by non-penetrating pressure fluid condition.