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Synthesis of metal-organic frameworks: A mini review
안화승,Yu-Ri Lee,Jun Kim 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.9
Metal organic frameworks (MOFs) are porous crystalline materials of one-, two-, or three-dimensional networks constructed from metal ions/clusters and multidentate organic linkers via coordination bonding, which are emerging as an important group of materials for energy storage, CO2 adsorption, alkane/alkene separation, and catalysis. To introduce newcomers in chemical engineering discipline to the rapidly expanding MOF research works, this review presents a brief introduction to the currently available MOFs synthesis methods. Starting from the conventional solvothermal/hydrothermal synthesis, microwave-assisted, sonochemical, electrochemical, mechanochemical, ionothermal, drygel conversion, and microfluidic synthesis methods will be presented. Examples will be limited to those representative MOF structures that can be synthesized using common organic ligands of 1,4-benzenedicarboxylic acid (and its functionalized forms) and 1,3,5-benzenetricarboxylic acid, in conjunction with metal nodes of Zn2+, Cu2+, Cr3+, Al3+,Fe3+ and Zr4+. Synthesis of widely-investigated zeolitic imidazolate framework (ZIF) structure, ZIF-8 is also included.
Hydrothermal synthesis of zeolite L in a Na+/K+ mixed alkali system
안화승,Yong Sig Ko 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.6
Zeolite L was prepared from the substrate system of Na2O-K2O-Al2O3-SiO2-H2O at temperatures of 373- 443 K by hydrothermal crystallization. The influence of various synthesis parameters such as the concentration ratios of the components, starting raw materials, synthesis temperature, gel aging, and stirring on the crystallization was investigated. Investigations revealed that the crystallinity of zeolite L crystals depends on molar ratios of the components such as SiO2/Al2O3, (K2O+Na2O)/SiO2, Na2O/(K2O+Na2O), and H2O/(K2O+Na2O). Pure and highly crystalline zeolite L could be obtained from a gel with the molar composition 5.4K2O-5.7Na2O-Al2O3-30SiO2-500H2O after 24 h at 443 K. It was found that the silica source affected the crystal size of zeolite L, and as the synthesis temperature increased, the average crystal size became larger. The crystal size could be decreased significantly by stirring the gel or subjecting the substrate mixture to an aging treatment at room temperature prior to the hydrothermal treatment. Thermal stability of the zeolite L crystals obtained was also briefly investigated.
Synthesis, Characterization, and Applications of Organic-Inorganic Hybrid Mesoporous Silica
안화승,정원조,정진성,고정호,Dong-Jun Kim 한국화학공학회 2004 Korean Journal of Chemical Engineering Vol.21 No.1
Organic-inorganic hybrid mesoporous materials composed of homogeneously distributed ethane group in a silica framework were prepared by using 1,2 bis(trimethoxysilyl) ethane (BTME) as a precursor and alkyltrimethylammonium- chloride or -bromide surfactant as a structure directing agent with or without the presence of a swelling agent, mesitylene. Characterization of the materials was performed by XRD, TEM/SEM, 29Si-/13C-solid state NMR, and N2-adsorption. Testing of the hybrid material as a reversed phase HPLC column stationary phase after C18 surfacefunctionalization demonstrated a promising result, which closely approaches the performance of a commercial product. Mn-salen complex tethering on the hybrid material produced a catalyst with somewhat enhanced performance in liquid phase etherification with tert-butyl hydroperoxide as oxidant.
안화승,고용식 한국화학공학회 1993 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.31 No.6
국산 왕겨를 이용하여 활성탄 제조에 관한 연구를 수행하였다. 왕겨를 탄화하여 얻은 char는 탄화온도가 증가함에 따라 비표면적이 증가하였으며, char를 끓는 물로 세척하거나 가성소다 용액을 이용하여 왕겨 char로부터 실리카를 용출시켜 비표면적을 증대시킬 수 있었다. 왕겨 char로부터 실리카를 용출시킨 경우. 비표면적과 제거된 실리카의 양은 NaOH의 첨가가 단계적으로 이루어질 때 증가하였다. 또한 왕겨로부터 인산을 활성화제로 사용하여 활성탄을 제조하고, 제조조건에 따른 비표면적과 흡착능을 검토하였다. 회분식 흡착실험을 통하여 페놀을 흡착시킨 결과, 활성탄의 흡착능은 비표면적이 클수록 증가하였으며, 페놀의 흡착량과 평형농도 사이에는 Freundlich의 흡착평형관계식이 성립하였다. 일본 Calgon F300 활성탄과 비교하여 페놀에 대한 흡착능을 시험한 결과 인산으로 활성화하여 제조한 활성탄의 흡착성능이 다소 우수하였다. A study was conducted to make activated carbon adsorbents using local rice hull ashes. As the carbonization temperature of the rice hull was increased, the specific surface area of the char increased steadily. The specific surface area of the char was enhanced either by boiling water washing, or by silica leaching using sodium hydroxide. When sodium hydroxide was used to leach out silica from the char, the specific surface area and the amount of silica removed increased most when the sodium hydroxide leaching was conducted in several stages. Activated carbon was also prepared from the rice hull by chemical activation method using phosphoric acid. The adsorption characteristics of phenol onto the activated carbons prepared were measured in a batch reactor. These results showed that as the specific surface areas of the activated carbons increased, better adsorptivities to phenol were obtained. The relationship between the amount of phenol adsorbed and equilibrium concentration was found to be well represented by the Freundlich isotherm. The adsorption capacity of the activated carbon prepared through chemical activation method was slightly better than that of the commercial product of Calgon F300.