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Journal of the Korean Ceramic Society Vol. 46, No., pp. 288~294, 2009. DOI:10.4191/KCERS.2009.46..288 Synthesis of AlO(OH) Nano Colloids from γ-al 2 O via Reversible Process Hyun Ran Cho, Sook Hyun Kim, and Byung Ki Park Energy Materials Research Center, Korea Research Institute of Chemical Technology, Daejeon 05-600, Korea (Received March 17, 2009; Accepted April 1, 2009) γ-al 2 O l ƒ w AlO(OH) ù g w x Á½ xá» w yw l (2009 17 ; 2009 4 1 ) ABSTRACT The platelet AlO(OH) nano colloids were prepared by hydrothermal reaction of the γ-al 2 O obtained with dehydration of γ-alo(oh) and dilute CH COOH solution. In hydrothermal reaction process, reversible reaction was accompanied between γ-al 2 O and AlO(OH), and hydrothermal reaction temperature, hydrothermal reaction time and CH COOH concentration had an effect on the crystal structure, surface chemical property, surface area, pore characteristics and crystal morphology of the AlO(OH) nano colloid particles. In this study, it was investigated to the hydrothermal reaction condition of the AlO(OH) nano colloid for using catalyst support, heat resisting agent, adsorbents, binder, polishing agent and coating agent. The crystal structure, surface area, pore volume and pore size of the platelet AlO(OH) nano colloids were investigated by XRD, TEM, TG/DTA, FT-IR and N 2 BET method in liquid nitrogen temperature. Key words : Aluminum salts, AlO(OH), Colloids, Catalysts, Coating materials 1. Al 2 O 2,040 o C š, ƒ 9 ƒ š. w yw w Ÿ w š. 1950 l yw, š» w š, 1960 l yw w ƒ»w ù t. ù κ, χ, ρ, η, γ, δ x ù θ, α, β š x ùƒ, ù w e. 1,5,11) Farkas, Gado boehmite (AlO(OH)) (AlO(OH)) 2d Al 2 O 1 1.0 ~ 1.8 swwš. 2-4,7) ù j» t ƒ jš, t ƒ w w p y»w. p» ù g Corresponding author : Byung Ki Park E-mail : bkpark@krict.re.kr Tel : +82-42-860-7022 Fax : +82-42-861-4245 v ƒ, ù ù t wƒ w e w»» w š. AlO(OH) w xk, t»œ vƒ jš, ƒwš w g ƒ. 6,9,10,12,1) AlO(OH) ½ pù p w w» w, ½ p w mw ù y g w w ƒ wwš w w ye, š» ƒ w g w g ƒ. 8,14-16) q AlO(OH) ù g e AlO(OH)ù ù γ-al 2 O š š w,, w. q AlO(OH) ù w š w ƒ w, ü p wš t ƒ f, ü,, ù,,, v, üy, 288

289 x Á½ xá», (Ž ),, y t š. 2) q AlO(OH) ù, w, t ywp, t,»œj» š xk j» yw p y w. 17-20) 2. x 2.1. x e AlO(OH) ù g w w» w pseudoboehmite(γ-alo(oh)) (Sasol, North America Inc.), CH COOH(Jin chemical pharmaceutical Co. LTD. 99%) w, e Muffle Furnace(VULCAN TM -550 ) w w lv g q š» w. 2.2. x e γ-alo(oh)» 500 o C 2 k w q AlO(OH) ù g γ- Al 2 O w. CH COOH q AlO(OH) ù g p w» w γ- Al 2 O 4g 16 g š» š CH COOH ƒƒ 0g, 0.4g, 0.8g, 1.2g, š 1.6 g ƒw 200 o C w. y w» w γ-al 2 O 4g 16 g š» š CH COOH 0.8 g ƒw 200 o C ƒƒ 1, 2,, 4 š 5 w. ƒ 200 o C w peptization w g x š, 200 o C w w š» w x ƒ w. CH COOH ƒ 1.6 g q AlO(OH) ù g yw yƒ, 1 w g ƒ x š, 5 xk» œp yƒ. 2.. e AlO(OH) ù g yw p w» w 110 o C 24 w. y w» w X- z»(xrd, Rigaku D/MAX-2200V X-Ray Diffractometer) w, interval 0.02, scan speed 5 o /min w 5 o = 2θ 80 o w. g e < = < O-H, Al-O-Al, Al-OH H-O-H w w» w Ÿ»(FT-IR, EQUINOX55) Fig. 1. XRD patterns of (a) γ-al 2 O as precursor and (b) γ- AlO(OH). w 400 ~ 4,000 cm -1 q rp w. w w» w œ»» 5 o C/min 1,200 o C¾ ƒ w (TG/DTA, TA Instruments SDT 2960) w š, xk y n x (TEM, TECNAI G 2 ) w. t,»œ v»œj» y N 2 BET (TriStar 000, Micro. Inst. Corp.) d w, w w AlO(OH) g 110 o C 24 k z agate mortar w w.. š Fig. 1 q AlO(OH) ù g γ- Al 2 O w» w γ-alo(oh) 500 o C 2 k w XRD ql š, Fig. 2 k ùkü. 400 o C γ-al 2 O w. γ- AlO(OH) topotactic transformation [AlO(OH)] 2 d w OH k Al + y γ-al 2 O. 4) γ-alo(oh) xk Fig. ƒ š ¼ e ùkü..1. t p y Fig. 4 XRD AlO(OH) ù g w CH COOH ƒ e w w. ƒ AlO(OH) ùkü, AlO(OH) CH COOH w w. w wz

로부터 가역과정을 경유한 AlO(OH) 나노콜로이드의 합성 γ-al2o Fig. 2. TGA/DTA curves of γ-alo(oh) used as precursor. Fig. 5. Fig.. 290 XRD patterns of the colloid as a function of the hydrothermal reaction time: (a) 1 h, (b) 2 h, (c) h, (d) TEM micrograph of γ-alo(oh) used as precursor. Fig. 6. DTA curves of the colloid as a function of the CH COOH concentration: (a) 0 g, (b) 0.4 g, (c) 0.8 g, 1,650cm 은 H-O-H기 이고,,200~,400cm 은 Al-OH기 의 신축진동인데, 모두 AlO(OH)의 화학적 결합구조를 나 타내는 것을 알 수 있다. 따라서 CH COOH의 첨가량에 관계없이 AlO(OH) 결정이 생성되고 그 구조도 유사하였 다. 이것은 결정구조와 화학적 결합구조는 수열합성에 따 라 변할 뿐 CH COOH의 첨가량에는 영향을 받지 않는다 는 것을 의미한다. Fig. 6의 DTA에서 알 수 있듯이 450 C 부근의 온도에서 동일한 흡열피크가 나타나는데, 이것은 AlO(OH) 결정 내부의 OH 이온이 응축되어 물로 이탈됨 으로써 γ-al O 로 상전이 한 것이다. Fig. 5의 XRD에서 보는바와 같이 1시간 수열합성 하였 1 1 o Fig. 4. XRD patterns of the colloid as a function of the CH COOH concentration: (a) 0 g, (b) 0.4 g, (c) 0.8 g, Fig. 8의 FT-IR에서 1,060~1,080cm 의 1 피크는 Al-OH기, 14,19) 2 을 경우에는 수열합성하기 전과 비교하여 상변화가 발생 제 46 권 제 호(2009)

291 x Á½ xá» Fig. 7. DTA curves of the colloid as a function of the hydrothermal reaction time: (a) 1 h, (b) 2 h, (c) h, (d) Fig. 9. FT-IR spectra of the colloid as a function of the hydrothermal reaction time: (a) 1 h, (b) 2 h, (c) h, (d) 4h, and (e) 5h. Fig. 8. FT-IR spectra of the colloid as a function of the CH COOH concentration: (a) 0 g, (b) 0.4 g, (c) 0.8 g, w γ-al 2 O w, 2 z x x š AlO(OH) j» w wì w z ƒ ƒw. Fig. 7 DTA š 2 z l 450 o C vjƒ ùkù, w ƒw γ-al 2 O ƒ ƒw w ùkü. Fig. 9 w ƒw -1,500cm Al- O-Al» t OH» ƒ ƒ,200~,400cm 1 Al-OH» OH» rp ùküš8), r p»ƒ ƒw Al + OH AlO(OH) t yw w ƒ yw. Fig. 10. N 2 ads./des. isotherm of the colloid as a function of the CH COOH concentration: (a) 0 g, (b) 0.4 g, (c) 0.8 g,.2. t œ y Fig. 10 CH COOH k ùkü. CH COOH ƒw t»œ vƒ ûš, CH COOH ƒ 0.8 g ¾ t»œ vƒ ƒw z l w w ùkü. CH COOH ƒw Al + CH COO x x w š š [Al(H 2 O)OH] xk 2+ aquohydroxo complex gel w z l ü y AlO(OH) w. 8) t phƒ OH ƒ ƒ AlO(OH) w» w y y ƒ f w wz

γ-al 2 O l ƒ w AlO(OH) ù g w 292 Fig. 11. N 2 ads./des. isotherm of the colloid as a function of the hydrothermal reaction time: (a) 1 h, (b) 2 h, (c) h, (d) Fig. 12. Pore size distributions of the colloid as a function of the CH COOH concentration: (a) 0 g, (b) 0.4 g, (c) 0.8 g, y j j», Fig. 12» œj» s 100 ~ 200ç»œ š 200 ~ 400ç»œ w l. ù AlO(OH) t CH COO w ü t w x g ƒ. w CH COOH ƒ 100 ~ 200ç»œ w, t phƒ û OH ƒ - γ Al 2 O l AlO(OH) w y y ƒ w». Fig. 11 w ƒ k y ùkü. Fig. 1. Pore size distributions of the colloid as a function of the hydrothermal reaction time: (a) 1 h, (b) 2 h, (c) h, (d) BDDTƒ w 5ƒ mesopore p ùkü S x ù kû. hysteresis xk de Boerƒ w 5ƒ 1~2 w w œ ù k š w j»œ ùkü Type E xk š,»œ ùkü Type A ƒà. 14) 1~2 w w k š j Fig. 1 0 ~ 50ç»œ swwš». Fig. 1 0 ~ 50ç»œ 100 ~ 200ç»œ w w ùkü, w»œ v ƒwš z l»œj» ƒw»œ v t w w ùkü... xk y Fig. 14 CH COOH xk y ùkü TEM. k OH s ww γ-al 2 O + Al w œ ùkü. CH COOH ƒw w Al + 1 OH [Al(H 2 O)OH] x 2+ wš, ƒ a c w w Fig. 14 xk q w. ù CH COOH sww CH COO γ-al 2 O Al 2 x wš ƒ + epitaxial w s š ¼ ƒ ¼ q k. ù ) CH COOH CH COOH 0.4 g w g ƒ e x w š, 0.8 g 46«y(2009)

조현란 김숙현 박병기 29 의 첨가량과 시간을 조절하여 수열반응 하였을 때, 가역반 응이 수반되면서 판상 AlO(OH) 나노 콜로이드가 합성되었 다. 그리고 CH COOH을 0.8 g 첨가하고 시간 수열반응 하 였을 때 기공부피가 가장 높았으며, CH COOH의 첨가량이 증가할수록 길이가 긴 판상입자가 합성되었고, 수열반응시 간이 증가할수록 판상입자의 두께가 증가하는 경향을 나타 내었다. REFERENCES Fig. 14. TEM micrographs of the colloid as a function of the CHCOOH concentration: (a) 0 g, (b) 0.4 g, (c) 0.8 g, 1. B.C. Lippins and J.H. Dcboer, Study of Phase Transformations during Calciantion of Aluminum Hydoxides by Selected Area Electron Diffraction, Acta Crystallogr., 112-21 (1964). 2. B.E. Yoldas, Alumina Sol Preparation from Alkoxides, Ceram. Bull., 289-90 (1975).. Wells, A. F.: Structural Inorganic Chemistry, 5th Ed., Oxford (1984). 4. M. Bellotto, B. Rebours, and P. Euzen, Mechanism of Pseudo-boehmite Dehydration:Influence of Reagent Structure and Reaction Kinetics on the Transformation Sequence, Materials Science Forum, [2] 572-77 (1998). 5. K. H. Lee and B. H. Ha, Preparation and Characteristic for γ-alumina, J. Kor. Institute. Chem. Eng., [1] 28-5 (1996). 6. R. I. Zakharchenya, Influence of Peptization on the Properties of Alumina Produced from Boehmite Sols, J. Sol-Gel Sci. Tech., 179-86(1996). 7. K. Okada and T. Nagashima, Relationship between Formation Conditions, Properties, and Crystalline Size of Boehmite, J. Kor. Chem. Eng., [1] 28-5 (1996). 8. B. K. Park, J. K. Suh, J. M. Lee, and D. S. Suhr, The Rehydration Properties of Aphous Alumina Powder in Low Water/Alumina Ratio(in Korean), J. Kor. Ceram. Soc., [10] 1085-9 (1998). 9. S. J. YOO, W. S. Baek, H. J. Park, J. W. Lee, S. G. Kim, U. Y. Hwang, H. S. Park, and H. S. Yoon, Synthesis of Alumina Sol from Al Metal and Effect of Surface Characterization by Aging in the Sol Preparation, HWAHAK KONGHAK, [] 71-76 (2002). 10. B. K. Park, J. K. Suh, J. M. Lee, and D. S. Suhr, Preparaton of High-capacity Ceramic Catalytic Support from Gibbsite (in Korean), J. Kor. Ceram. Soc., [] 245-51 (2002). 11. R. Petrovic, S. Milonjic, V. Jokanvic, Lj. Kostic-Gvozdennovic, I. Petrovic-prelevic, and Dj. Janackovic, Influence of synthesis parameters on the structure of boehmite sol particles, Powder Tech., 185-89 (200). 12. B. K. Park, J. M. Lee, and D. S. Suhr, Preparation of Fe2O Supported γ-alumina Catalyst by Hydrothermal Method(in Korean), J. Kor. Ceram. Soc., [7] 68-89 (200). 1. B. K. Park, J. M. Lee, and D. S. Suhr, Effect of CHCOOH Concentration on Characteristics of Fe2O Supported γ-alumina Catalyst by Hydrothermal Method(in Korean), J. Kor. Ceram. Soc., [8] 758-64 (200). 14. B. K. Park, H. S. Lee, Y. H. Kim, and J. M. Lee, Prep17 54 271 4 6 4 Fig. 15. TEM micrographs of the colloid as a function of the hydrothermal reaction time: (a) 1 h, (b) 2 h, (c) h, (d) 때부터 콜로이드가 형성되었지만 CH COOH의 첨가량이 증가함에 따라 콜로이드 용액의 점도는 증가하는 경향을 보였다. Fig. 15의 TEM 사진에서 보는바와 같이 수열반응시간 이 증가함에 따라 CH COOH 용액에서 침상입자는 용해 되어 판상형태로 재결정하는 것을 알 수 있다. Fig. 5의 XRD 및 Fig. 15의 TEM 사진을 통해 2시간 까지는 침상 의 γ-al O 가 서서히 용해하여 대부분 무정형의 겔과 소 량의 AlO(OH) 결정을 석출하기 시작하여 시간 이후부 터 판상 AlO(OH)로 재결정된다. 4시간까지는 결정이 성 장하여 입자의 크기가 증가하며, 5시간부터는 판상입자의 두께가 증가하는 경향을 나타내었다. 2 4. 결 론 침상의 γ-alo(oh)를 소성하여 얻은 γ-al O 를 CH COOH 2 한국세라믹학회지 5 40 9 1 40 40

γ-al 2 O l ƒ w AlO(OH) ù g w 294 aration of Porous Boehmite Gel from Waste AlCl Solution(in Korean), J. Kor. Ceram. Soc., 40 [11] 864-71 (2004). 15. B. K. Park, J. M. Lee, D. S. Suhr, and K. S. Lim, Preparation of γ-al 2 O Platelets from Aluminum Hydroxides Gel(in Korean), J. Kor. Ceram. Soc., 41 [8] 610-17 (2004). 16. J. W. Lee, H. S. Yoon, U S. Chae, H. J. Park, U. Y. Hwang, H. S. Park, D. R. park, and S. J. Yoo, A Comparison of Structural Characterization of Composite Alumina Powder Prepared by Sol-Gel Method According to the Promoters, Korean Chem. Eng. Res., 4 [4] 50-10 (2005). 17. D. U. Choe, B. K. Park, J. K. Suh, and J. M. Lee, Effect of Aging Time of AlO(OH) Gel Precipitated by Hydrolysis of Aluminum Sulfate on Crystal Growth of the Flaky α- Al 2 O (in Korean), J. Kor. Ceram. Soc., 4 [9] 575-81 (2006). 18. D. U. Choe, B. K. Park, and J. M. Lee, Effect of Water and Aluminum Sulfate Mole Ratio on Pore Characteristics in Synthesis of AlO(OH) Nano Gel by Homogeneous Precipitation(in Korean), J. Kor. Ceram. Soc., 4 [9] 564-68 (2006). 19. B. K. Park, D. U. Choe, and J. R. Lee, Effect of ph on Pore Characteristics in Synthesis of High Porous AlO(OH) Gel by Hydrolysis of Al 2 (SO 4 ) and Na 2 SO 4 Mixed Solution, J. Kor. Ceram. Soc., 44 [6] 25-0 (2007). 20. D. U. Choe, B. K. Park, J. K. Suh, and J. M. Lee, Effect of ph on Pore Characteristics in Synthesis of High Porous AlO(OH) Gel by Hydrolysis of Al 2 (SO 4 ) and Na 2 SO 4 Mixed Solution(in Korean), J. Kor. Ceram. Soc., 44 [6] 25-0 (2007). 46«y(2009)