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.

Catalytic Properties of Ti-HMS with High Titanium Loadings

안화승,M. J. Kim,J. R. Ko,S. H. Jang 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.8

Ti-HMS samples in which titanium species exist in various forms of isolated tetrahedral state, finely dispersed TiO2 cluster, and some in extra-framework anatase phase were prepared via a direct synthesis route using dodecylamine (DDS) as a structure directing agent by systematically varying the titanium loadings between 2 and 50 mol% Ti/(Ti+Si) in substrate composition. Physicochemical properties of the materials were evaluated using XRD, SEM/TEM, N2 adsorption, UV-vis and XANES spectroscopies. Catalytic properties of Ti-HMS in cyclohexene and 2,6-di-tert-butyl phenol (2,6-DTBP) oxidation using aqueous H2O2, and vapor phase photocatalytic degradation of acetaldehyde were evaluated. High H2O2 selectivity was obtained in cyclohexene oxidation, and cyclohexene conversion was found primarily dependent on the amount of tetrahedrally coordinated Ti sites. For bulky 2,6-DTBP oxidation and photocatalytic oxidation of acetaldehyde, on the other hand, conversions were found dependent on the total amount of Ti sites and maintaining an uniform mesoporous structure in the catalysts was not critical for efficient catalysis.

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.

총설 : 금속유기구조체를 이용한 이산화탄소 흡착 연구

안화승 ( Wha Seung Ahn ),김준 ( Jun Kim ),김희영 ( Hee Young Kim ) 한국화학공학회 2013 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.51 No.2

금속유기구조체(metal-organic frameworks, MOF)는 넓은 비표면적, 규칙적인 구조 및 높게 분산된 금속 성분 등 뛰 어난 물리화학적 특성으로 인해 활발한 연구가 이뤄지고 있는 다공성 물질이며, 특히 가스의 흡착, 분리 매체로서 뛰 어난 성능이 보고되고 있다. MOF를 이용한 온실가스 이산화탄소의 흡착 연구는 상온 고압 영역에서 이산화탄소 저장 공정과 상온 저압 영역에서 이산화탄소 흡착 공정의 두 범주로 나눌 수 있으며, MOF의 넓은 비표면적 외에도 (1) MOF 의 빈 배위결합 자리, (2) MOF의 기능화, (3) MOF의 상호 침투 효과, 및 (4) 이온 교환 효과를 이용한 연구 결과가 보고되고 있다. MOF 물질들은 비교적 낮은 수분 및 열에 대한 안정성이 문제로 제기되고 있으며, 제올라이트 유사 구 조체(zeolitic imidazolate frameworks, ZIF) 또는 유기 골격 구조체(covalent organic frameworks, COF) 물질의 이산화 탄소 흡착 특성이 거론되고 있다. 본 소고에서는 MOF를 이용한 이산화탄소 흡착에 대한 최근의 연구 결과를 본 연구 실의 실험 결과를 중심으로 간략히 소개하고자 한다. Metal organic frameworks (MOFs) are a class of crystalline organic-inorganic hybrid compounds formed by coordination of metal clusters or ions with organic linkers. MOFs have recently attracted intense research interest due to their permanent porous structures, large surface areas and pore volume, high-dispersed metal species, and potential applications in gas adsorption, separation, and catalysis. CO2 adsorption in MOFs has been investigated in two areas of CO2 storage at high pressures and CO2 adsorption at atmospheric pressure conditions. In this short review, CO2 adsorption/ separation results using MOFs conducted in our laboratory was explained in terms of four contributing effects; (1) coordinatively unsaturated open metal sites, (2) functionalization, (3) interpenetration/catenation, and (4) ion-exchange. Zeolitic imidazolate frameworks (ZIFs) and covalent organic frameworks (COFs) were also considered as a candidate material.

Sonochemical Synthesis of Cu_3(BTC)_2 in a Deep Eutectic Mixture of Choline Chloride/dimethylurea

Sun-Hee Kim,Seung-Tae Yang,Jun Kim,안화승 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.8

초음파 합성법을 이용한 UiO-66의 합성 및 이산화탄소 흡착/자일렌 이성체 분리 연구

김희영 ( Hee Young Kim ),김세나 ( Se Na Kim ),김준 ( Jun Kim ),안화승 ( Wha Seung Ahn ) 한국화학공학회 2013 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.51 No.4

초음파-용매열 혼합방법으로 염화지르코늄과 1,4-benzenedicarboxylic acid를 사용하여 다공성 금속유기 구조체인 UiO-66을 1-L 규모로 제조하였다. 합성 개시 2시간 뒤 약 0.2 μm의 작고 고른 형태와 1,375㎡/g의 높은 비표면적을 갖는 결정을 95%의 높은 수율로 얻을 수 있었다. 제조된 UiO-66 물질의 이산화탄소 흡착 거동을 조사한 결과, 1기압 273 K 및 298K에서 각각 198 및 84 mg/g의 흡착량과 32:1 이상의 높은 질소 대비 이산화탄소 흡착 선택성을 갖는 것을 확인하였다. 흡착이 진행됨에 따라 흡착열은 33에서 25 kJ/mol 로 감소하였다. 또한 UiO-66 물질을 사용하여 액상 회분식 조건에서 자일렌 이성체의 분리 연구를 수행하였으며, o-자일렌이 단일성분 최대 흡착능 및 경쟁흡착에서도 m-, p-자일렌 대비 약 2배 이상의 높은 흡착 선호도를 갖는 것을 확인할 수 있었다. Zr-benzendicarboxylate structure, UiO-66 was prepared in 1-L batch scale by using a unique sonochemical-solvothermal combined synthesis method. The produced UiO-66 showed uniform particles of ca. 0.2 μm in size with the BET surface area of 1,375㎡/g in high product yield (>95%). The UiO-66 showed 198 and 84 mg/g CO2 adsorption capacity at 273 K and 298 K, respectively, with excellent CO2 selectivity (CO2:N2=32:1) at ambient conditions. The isosteric heat of CO2 adsorption varied from 33 to 25 kJ/mol as the adsorption progressed. The UiO-66 tested for xylene isomer separation in a liquid-phase batch mode confirmed preferential adsorption of the adsorbent for o-xylene over m-, and p-xylene.

HΒ- zeolite 촉매상에서 Toluene 의 불균등화 반응

박기모,안화승,김건중 ( Gi Mo Park,Wha,Seung Ahn,Geon Joong Kim ) 한국공업화학회 1997 한국공업화학회 연구논문 초록집 Vol.1997 No.0

포스터 발표 - 무기재료분과 / 전기화학분과 / 촉매분과 : HΒ- zeolite 촉매상에서 Toluene 의 불균등화 반응

박기모,안화승,김건중 ( Gi Mo Park,Wha,Seung Ahn,Geon Joong Kim ) 한국공업화학회 1997 한국공업화학회 연구논문 초록집 Vol.1990 No.3

Methyl tert-Butylether 合成에 미치는 HZSM-5 觸媒의 SiO$_2/Al_2O_3$ 比의 영향

김건중,안화승,조병린,권이묵,Geon-Joong Kim,Wha-Seung Ahn,Byung-Rin Cho,Lee-Mook Kwon 대한화학회 1989 대한화학회지 Vol.33 No.1

HZSM-5를 觸媒로 하여 메탄올과 이소부틸렌으로부터 Methyl tertiary butyl ether(MTBE)의 氣相合成實驗을 하였으며, zeolite 觸媒의 SiO$_2/Al_2O_3$ 比 및 反應條件의 영향을 硏究하였다. 각 觸媒들은 pyridine을 吸着시켜 temperature programmed desorption(TPD) 및 IR法으로 酸點의 세기와 特性을 조사하였으며, 승온탈착실험을 통하여 각 反應物 및 生成物의 吸着特性을 검토하였다. HZSM-5의 SiO$_2/Al_2O_3$比가 증가할수록 强한 酸點의 수는 감소하여 메탄올의 脫水反應은 억제되고 MTBE에 대한 선택도가 증가하였다. MTBE에 대한 전환율과 선택도는 $i-C_4H_8$의 細孔內 확산저항에 의하여 큰 영향을 받음을 알 수 있었다. MTBE合成反應은 發熱的이어서, 전반적으로 80$^{\circ}$C의 반응온도가 合成에 적합하였다. 한편 각 觸媒上에 生成된 coke의 特性을 TG, DTA 및 IR spectrum으로 측정하였다. 침착된 coke의 量은 HY > H-Mordenite > HZSM-5順이었으며, H-Mordenite에 있어서는 누적된 coke의 양이 HZSM-5보다 현저하지는 않았으나, 細孔의 配向이 1方向性이므로 반응시간이 길어짐에 따라 심한 活性減退가 일어났다. HY는 큰 細孔을 가지고 있어 M$i-C_4H_8$의 重合이 쉽게 일어났으며, HZSM-5에 비하여 많은 coke의 참착과 빠른 活性減退를 나타내었다. Methyl tert-butyl ether(MTBE) was synthesized from vapor phase reaction of methanol with iso-butylene over HZSM-5 catalysts, and effects of SiO$_2/Al_2O_3$ ratio in the HZSM-5 catalysts and reaction conditions on products distribution have been examined. Acid strength and acid type of each catalyst with different SiO$_2/Al_2O_3$ ratio were measured using pyridine adsorption followed by temperature programmed desorption(TPD) and IR analysis. Reactants and products adsorption characteristics on different acid sites have also been examined. As the SiO$_2/Al_2O_3$ ratio of HZSM-5 catalyst was increased, selectivity to MTBE was improved as a result of decrease in dimethylether(DME) formation at the strong acid sites. Conversion and selectivity to MTBE were also greatly enhanced as $i-C_4H_8/CH_3OH$ reactant ratio was increased, and overall about 80$^{\circ}$C was adequate for the MTBE synthesis. The properties of deposited coke on spent catalysts were examined by TG, DTA and IR spectrum analysis, indicating the amount of the coke deposit in the order of HY > H-Mordenite > HZSM-5. Even if the coke deposited on H-Mordenite was little more in amount than to that on HZSM-5, the former deactivated quickly due to its non-interconnected channel structure. For HY, owing to its lange pore size, significant $i-C_4H_8$ polymerization was occured, and rapid deactivation and severe coke formation has resulted within few hours.

Methyl Isobutyl Ketone 의 촉매소각에 대한 연구

김진식,안화승 ( J . S . Kim,W . S . Ahn ) 한국공업화학회 1995 공업화학 Vol.6 No.4

대표적인 귀금속 및 전이금속 산화물 촉매들을 제조하여 Methyl Isobuthyl Ketone의 연소반응에 대한 활성도를 비교하였다. 이때 Pd/Al₂O₃와 CuCr₂O₄/Al₂O₃의 활성도가 특히 우수하였으며, Co₃O₄를 제외한 나머지의 촉매들은 고온에서 장시간동안 활성을 유지하였다. 403-443 K 범위에서 적분형 반응기를 이용하여 kinetics실험을 수행한 결과, Pd와 CuCr₂O₄의 활성화 에너지는 9.2 및 11.4Kcal/mol이었다. Monolith type 촉매전환장치의 운행조건 및 설계변수의 변화에 따른 정상상태 response를 수학적 모델을 이용하여 계산한 결과 실제공정의 조건에서 대부분의 경우 연소과정이 물질전달 지배영역에서 진행됨을 알 수 있었다. 반응물의 높은 유입온도와 농도 및 낮은 유입속도에서 높은 전환율을 얻을 수 있었으며, cell density가 클수록 유기용매의 제거성능이 우수하였다. 또한 channel의 크기와 모양이 전환율 및 온도분포에 중요한 영향을 미침을 알 수 있었다. Activities of precious metals and selected transition metal oxide catalysts for methyl isobuthyl ketone(MIBK) combustion were measured, and among the catalysts tested, Pd/Al₂O₃ and CuCr₂O₄/Al₂O₃ were found most effective. Kinetic experiments were conducted using an integral reactor for Pd and CuCr₂O₄ catalysts. In the temperature range of 403-443 K, activation energies for Pd and CuCr₂O₄ catalyst on MIBK oxidation were estimated to be 9.2 and 11.4Kcal/gmol, respectively. Steady state responses of a monolith catalytic incinerator to changes in operating conditions or monolith design parameters have been examined on the basis of one dimensional mathematical model. Calculations showed that, under typical operating conditions, the catalyst system is operating under mass transfer controlled conditions. Higher conversion efficiencies were obtained with higher inlet temperatures and higher MIBK concentrations, and with low gas velocities. Monoliths having higher channel densities offer superior performances. It was implicated that channel size and shape can have significant influences on the conversion and temperature profiles along the monolith channels.