Syn thesis and Character iza tion of CoAPO -11 M olecular Sieve from a Non-aqueous System 3

Transcription

1 V o l. 15 N o Chem ical R esearch in Ch inese U niversities Syn thesis and Character iza tion of CoAPO -11 M olecular Sieve from a Non-aqueous System 3 J IAO X iu2ling, YAO You2w ei, PAN G W en2qin 3 3 and XU R u2ren (D ep artm ent of Chem istry, J ilin U niversity, Chang chun, ) (R eceived Sep ṫ 9, 1998) CoA PO 211 mo lecular sieve w ith a h igh crystallinity w as p repared by hydro therm al synthesis from a non2aqueous system (EG) in the p resence of E t2n H o r i2p r2n H as a structure2directing agen ṫ T he X2ray diffraction (XRD ) pattern s and scann ing electron m icrograph s (SEM ) revealed that the p roduct pow der w as pure and homogenous in particle2size. T he X2ray pow der diffraction data, com po sitional analysis, therm al stability analysis and UV 2V is diffuse reflectance spectro scop ic analysis show ed that Co ( g ) ions w ere inco rpo rated in the alum inopho sphate fram ew o rk and tetrahedrally coo rdinated in the lattice of as2p repared samp les. Ke yw o rds H ydro therm al synthesis, CoA PO 211, N on2aqueous system, M o lecular sieve In troduction Fo llow ing the syn theses of alum inopho sphate fam ily of mo lecu lar sieves (A lpo 42n ) in 1982 [1 ], a series of M ea PO 2n (M e= M g, M n, Co o r Fe, etc. ), the fram ew o rk sub stitu ted analogues, w as first repo rted in 1985 [2 ]. To inco rpo rate tran sition m etal ion s in to the fram ew o rk of alum inopho sphate mo lecu lar sieves can increase the stab ility of the m etal ion fo r catalytic reaction s and con tro l the acidity of the mo lecu lar sieves. Several papers availab le discu ssed the syn thesis condition s in relation to the structu re types ob tained [3_ 7 ], and the Co2con tain ing m icropo rou s alum inopho sphates have been the sub ject of m any investigation s [7_ 10 ]. How ever, there has been little info rm ation on m icropo rou s cobalt sub stitu ted alum inopho sphate mo lecu lar sieves syn thesized from non2aqueou s system ṡ T he p resen t paper covers the hydro therm al syn thesis of pure CoA PO 211 mo lecu lar sieve from an alcoho l system and gives som e details on the syn thesis and characterization of the p roduct. Exper im en tal Cobalt acetate w as added to a m ix tu re of alum in ium iso2p ropox ide and ethylene glyco l under stirring. A fter cobalt acetate w as w ell distribu ted, pho spho ric acid w as added to the m ix tu re w ith additional stirring. F inally, also under stirring, a temp late w as added drop by d rop. T he resu lted gel w a s fu rther st irred fo r 1 _ 2 h and reacted in a sta in less steel au toclave w ith a T eflon liner under au togeneou s p ressu re fo r abou t 14 d at T he samp les w ere filtered and w ashed w ith an excess of deion ized w ater, then dried at room temperatu re. T he XRD pattern s w ere reco rded on a R igaku D gm A X2g A diffractom eter w ith Cu K Α 3 Suppo rted by the N ational N atural Science Foundation of Ch ina and the State Key L abo rato ry of C rystal of Shandong U niversity. 3 3 To w hom co rrespondence should be addressed.

2 N o. 2 J IAO X iu2ling, YAO You2w ei, PAN G W en2qin et al. 97 tendency to fo rm hydrogen2bonding of the o rgan ic mo lecu les. 2 Character iza tion T he X 2ray pow der d iffract ion da ta of the p roduct a re listed in T ab le 2. T he inco rpo ration of cobalt in to A lpo 4211 fram ew o rk led to an increase in b and a axes, w hereas it led to a decrease in c ax is. F rom the A EL structu re, w e can calcu late that the sub stitu tion of A l 3+ by Co 2+ can lead a and b axes a sign ifican t increase. A s a resu lt, it resu lts in an increase of un it cell vo lum e. Since the radiu s of Co 2+ is larger than that of A l 3+, the inco rpo ration of Co 2+ in to the alum inopho sphate fram ew o rk m akes the un it cell vo lum e larger. W ith the increase of n (CoO ) gn (A l2o 3) value in the p roduct, the vo lum e gradually increa sed. Table 2 The un it cell parameters P roduct n (CoO ) gn (A l2o 3) a n (CoO ) gn (A l2o 3) b cgnm bgnm agnm V gnm 3 A lpo CoA PO CoA PO a. In gel m ixture; b. in p roduct and based on ICP analysis. F ig. 1 show s the XRD pattern s of as2p repared and calcined samp les w ith differen t n (CoO ) gn (A l2o 3) ratio ṡ It can be seen that the therm al stab ility decreased w ith the increase of n (CoO ) gn (A l2o 3) in the p roduct. A fter calcined at 700 fo r abou t 5 h, the samp le w ith h igher n (CoO ) gn (A l2o 3) [n (CoO ) gn (A l2o 3) = in the p roduct ] tran sferred to A lpo 42tridym ite, w h ile the samp le w ith low er n (CoO ) gn (A l2o 3) [n (CoO ) gn (A l2o 3) = in the p roduct ] also rem ained to be the A lpo 4211 structu re. T he radiu s of Co 2+ is larger than that of A l 3+ and the Co_ O bond length is longer than that of A l_ O, the sub stitu tion of A l 3+ by Co 2+ w ill resu lt in the disto rtion of the lattice, w h ich m igh t lead to the decrease of the therm al stab ility [12 ]. T hen, it s suggested that the decrease of the therm al stab ility of the p roduct w ith the increase of the n (CoO ) gn (A l2o 3) value confirm s that Co (g ) has been inco rpo rated in to the fram ew o rk of the alum inopho sphate mo lecu lar sieve. T hu s, the fram ew o rk of as2p repared CoA PO 211 has the negative charge fo r the rep lacem en t of A l 3+ by F ig. 1 XRD patterns of as2p repared (a) and calcined CoA PO 211 (b. 600 fo r 5 h, c. 700 fo r 5 h) w ith different n (CoO ) gn (A l2o 3) ratio ṡ (A ) n (CoO ) gn (A l2o 3) = 0; (B) n (CoO ) gn (A l2o 3) = ; (C) n (CoO ) gn (A l2o 3) =

3 N o. 2 J IAO X iu2ling, YAO You2w ei, PAN G W en2qin et al. 99 system, and the m ain conclu sion s are as fo llow s. (1) R eaction condition s, such as reaction temperatu re and n (CoO ) gn (A l2o 3) ratio w e investigated, and the op tim al condition s have been given the reaction s w ere carried ou t at fo r 12_ 14 d w ith n (CoO ) gn (A l2o 3) < (2) T he UV 2V is diffu se reflectance spectrum confirm ed that Co 2+ had been inco rpo rated in to the fram ew o rk of A lpo 4211 mo lecu lar sieve and w as tetrahedrally coo rdinated, and the X2ray pow der diffraction data show ed that the un it cell w as expanded w ith the increase of n (CoO ) gn (A l2o 3) in the p roduct. W ith the increase of the cobalt con ten t in the p roduct, the therm al stab ility of the samp les greatly decreased. Re fe re nce s [ 1 ] W ilson, S. T., L ok, B. M., M essina, C. A. et al., J. Am. Chem. Soc., 104, (1982) [ 2 ] W ilson, S. T. and F lanigen, E. M., Eur. Paṫ A (1985) [ 3 ] F lanigen, E. M., Patton, R. L. and W ilson, S. T., Stud. Surf. Sci. Catal., 37, 13 (1988) [ 4 ] O jo, A. F. and M ocusker, L. B., Zeo lites, 11, 460 (1991) [ 5 ] W ilson, S. T., Stud. Surf. Sci. Catal., 58, 460 (1991) [ 6 ] U ytterhoeven, M. G., Schoonheydt, R. A., M icropo rous M aterials, 3, 265 (1994) [ 7 ] Q iu, S., T ian, W., Pang, W. et al., Zeo lites, 11, 371 (1991) [ 8 ] M ontes, C., D avis, M. E., M urray, B. et al., J. Phys. Chem., 94, (1994) [ 9 ] K raushaar2czarnetzk i, B., Hoogervo rst, W. G. M., A ndrea, R. R., et al., J. Chem. Soc. Faraday T ranṡ, 87 (6), 891 (1991) [10 ] H an, H. S. and Chon, H., M icropo rous M aterials, 3, 331 (1994) [11 ] P luth, J. J., Sm ith, J. V. and R ichardson, J. W. J ṙ, J. Phys. Chem., 92, (1988) [12 ] H an, S. Y., Yan, C. C., Guo, Y. et al., A cta Scientiarum N aturalium U niv. J ilinensis, (1), 104 (1989) [13 ] Co tton, F. A. and W ilk inson, G., A dv. Ino rg. Chem., John W iley, N ew Yo rk, 1982, 725 [14 ] L ever, A. B. P., Ino rgnic E lectronic Spectro scopy, E lsevier, Am sterdam, 1984, 479 [15 ] P izarro, T. L., V illeneuve, G. and H agenm uller, P., J. So lid State Chem., 92, 273 (1991)

4 V o l. 15 N o Chem ical R esearch in Ch inese U niversities Prepara tion and Character iza tion of Ternary Europ ium Com plex-d oped Th in Sol-Gel Hybr id F ilm by Fluorescence Spectroscopy 3 FU L ian2she, ZHAN G Hong2jie 3 3, W AN G Shu2b in M EN G Q ing2guo, YAN G Ku i2yue and N I J ia2zuan (L aboratory of R are E arth Chem istry and P hy sics, Chang chun Institu te of A pp lied Chem istry, Ch inese A cad em y of S ciences, Chang chun, ) (R eceived O cṫ 15, 1998) T ernary europ ium comp lex w ith dibenzoylm ethane (DBM ) and 1, 102phenanth ro line (phen ) w as in2situ synthesized in th in SiO 2gpo lyvinyl butyral (PVB ) hybrid film s by a tw o2step so l2gel p rocess and characterized by m eans of fluo rescence spectro scopy. T he lum inescence spectra, fluo rescence lifetim es and pho to stability w ere all investigated. T he results show ed that the hybrid film s exh ibited the characteristic em ission bands of the central rare earth Eu 3+. In addition, Eu 3+ p resented longer fluo rescence lifetim e than in an ethano l so lution and the comp lex had a h igher pho to stability in the hybrid film than in the PVB film containing the co rresponding pure comp lex. Ke yw o rds R are earth comp lex, In2situ synthesis, Tw o2step so l2gel p rocess, H ybrid film, F luo rescence spectro scopy In troduction T he low 2temperatu re p rocessing of the so l2gel m aterial m akes it po ssib le to en trap o rgan ic species easily w ith in a rigid glass m atrix [1 ]. So far th is m ethod has received con siderab le atten tion fo r the p reparation of so lid2state tunab le dye laser m edia u sing o rgan ic dye dop an t ṡ How ever, the key p rob lem s a ssocia ted w ith the dyes a re o rgan ic dyes p ho todecom po sit ion and lum inescence quench ing, w h ich lim it their app lica t ion lifet im e. Pho toactive rare earth o rgan ic comp lexes u sually exh ib it ex ten sive lum inescence due to the strong ab so rp tion of the o rgan ic ligands and efficien t energy tran sfer from the trip let state of the ligands to the cen tral rare earth ion s. Fu rthermo re, rare earth comp lexes show a h igher stab ility w ith respect to the o rgan ic dyes. In fact, som e w o rk has already been carried ou t abou t the p reparation and lum inescence p roperties of Eu 3+, T b 3+ and o ther rare earth comp lexes in so l2gel derived silica m atrix [2 15 ]. Specifically, M attew s et a l. [3 ] demon strated that the lum inescen t in ten sity of Eu (T T FA ) 3 w as greatly increased by app rox im ately an 3 Suppo rted by the N ational Key P ro ject fo r Fundam ental R esearch, the N ational N atural Science Foundation of Ch ina and N ational N oble Youth Fund of Scienceṡ 3 3 To w hom co rrespondence should be addressed.

5 102 Chem ical R esearch in Ch inese U niversities V o l. 15 pure comp lex and PVB w as dropped to the p late and operated as above. Fo llow ing th is p rocess, the p lates w ere removed, put in air fo r som etim e and then dried in a drying box. 4 Spectroscop ic M ea surem en t T he fluo rescence excitation and em ission spectra w ere reco rded on a SPEX F luo ro log2 2T 2 Spectrofluo rom eter equ ipped w ith a 450 W xenon lamp as the excitation sou rce. T he lum inescence lifetim e m easu rem en ts w ere perfo rm ed on a SPEX 1934D pho spho rom eter. Fo r pho to stab ility experim en ts, the slides w ere moun ted in a samp le ho lder. T he slides w ere irradiated by a 250 W h igh2p ressu re m ercu ry lamp w ith a ligh t filter w h ich tran sm itted the 365 nm spectral line of the lamp. T he distance betw een the slide and the cen ter of the lamp w as 6. 5 cm. T he m easu rem en ts w ere all carried ou t at room temperatu re (R T ). Results and D iscuss ion 1 Prepara tion of Hybr id F ilm Con ta in ing Europ ium Com plex in situ Syn thesized in Sol-gel M a tr ix T he film p reparation w as perfo rm ed by sp in2coating m ethod, in w h ich the so l w as ob tained by u sing a tw o2step so l2gel p rocesṡ A fter the comp lete hydro lysis of T EO S, (CH 2) 6N 4 w as added to the so l. (CH 2) 6N 4 w as u sed as the hydroxyl group s generato r to adju st the ph value [17 ]. H ydroxyl group s are gradually released th rough the reaction betw een w ater and (CH 2) 6N 4. A s a resu lt, the ph value of the system w as enhanced. T h is reaction m edium is su itab le no t on ly fo r rap id gelation bu t also fo r the fo rm ation of the rare earth comp lex. T he experim en tal resu lts indicated that eu rop ium comp lex w ith DBM and phen w as syn thesized in gel m atrix. Fu rthermo re, the inco rpo ration of PVB served to seal and coat the po res, resu lting in a h igher capacity of heat tran sm ission and low er scattering effects of the m arrix. Fo r th is reason, the lum inescence in ten sity w as increased. 2 Fluorescence Exc ita tion and Em ission Spectra F ig. 1 show s the excita t ion and em ission sp ect ra of the so l2gel derived hyb rid film. T he excita t ion sp ect rum (Κem = 612 nm ) con sists of a very b road band ranging from 260 nm to abou t 430 nm cen tered a t 360 nm in stead of the narrow band u sually peaked at around 395 nm fo r Eu 3+, suggesting that eu rop ium comp lex w as syn thesized in SiO 2gPVB m a t rix. T he em ission spectrum con tain s the characteristic tran sition s 5 D 0 7 F J (J = 0, 1, 2, 3, 4) of Eu 3+ peaked at 580, 592, 612, 651, 704 nm, respectively. F ig. 1 Excitation and em ission spectra of europ ium com p lex w ith DBM and phen synthesized in SiO 2gPVB m atrix. a. Excitation spectrum, Κem = 612 nm; b. em ission spectrum, Κex= 370 nm.

6 104 Chem ical R esearch in Ch inese U niversities V o l. 15 lum inescence lifetim e of Eu 3+ in SiO 2gPVB m atrix than in ethano l so lu tion. It is rem arkab le to no tice that the lifetim e fo r the comp lex in SiO 2gPVB m atrix is abou t th ree2fo ld long compared w ith that fo r the comp lex in ethano l so lu tion. Conclus ion s T ernary eu rop ium comp lex w ith DBM and phen can be in2situ syn thesized in th in hyb rid film s by a tw o 2step so l2gel p rocesṡ T he hyb rid film s exh ib it the cha racterist ic em ission bands of the cen tral rare earth Eu 3+. In addition, Eu 3+ p resen ts a longer fluo rescence lifetim e and the comp lex exh ib ite a h igher pho to stab ility in the hyb rid film ṡ T h is m ethod p rovides a new rou te fo r rap id p reparation of ino rgan icgpo lym er hyb rid m aterials. Re fe re nce s [ 1 ] Sakka, S., SP IE, 1758, 2 (1992) [ 2 ] Fu, L. S., Zhang, H. J., Shao, H. et al., Ch in. R are. Earth., 19 (2), 49 (1998) [ 3 ] M atthew s, L. R. and Knobbe, E. T., Chem. M ateṙ, 5, 1697 (1993) [ 4 ] M atthew s, L. R., W ang, X. and Knobbe, E. T., J. N on2crysṫ So lids, 178, 44 (1994) [ 5 ] J in, T., T sutsum i, S., D eguch i, Y. et al., J. E lectrochem. Soc., 142, L 195 (1995) [ 6 ] J in, T., T sutsum i, S., D eguch i, Y. et al., J. A lloys and Compounds, 252, 59 (1997) [ 7 ] J in, T., T sutsum i, S., D eguch i, Y. et al., J. E lectrochem. Soc., 143, (1996) [ 8 ] J in, T., Inoue, S., D eguch i, Y. et al., J. N on2c rysṫ So lids, 223, 123 (1998) [ 9 ] Su, Q. D., Gao, K. X., T ao, Y. et al., Chem. J. Ch inese U niversities, 19 (4), 526 (1998) [10 ] L in, J., L i, B., Zhang, H. J. et al., Ch in. J. Chem., 15 (4), 327 (1997) [11 ] Yan, B., Zhang, H. J., W ang, S. B. et al., M ateṙ Chem. and Phys., 51, 92 (1997) [12 ] Yan, B., Zhang, H. J., W ang, S. B. et al., J. Pho tochem. Pho tobio l. A : Chem., 112, 231 (1998) [13 ] Yan, B., Zhang, H. J., W ang, S. B. et al., Ch in. Chem. L etṫ, 8 (7), 633 (1997) [14 ] Q ian, G. D., W ang, M. Q., W ang, M. et al., J. M ateṙ Sci. L etṫ, 16, 322 (1997) [15 ] Q ian, G. D. and W ang, M. Q., J. Phyṡ Chem. So lids, 58, 375 (1997) [16 ] Sam elson, H. and L emp ick i, A., J. Chem. Phys., 39, 110 (1963) [17 ] Kan, H. H., Zhang, D. H., Yang, H. et al., J. M ateṙ Sci. L etṫ, 16, 190 (1997) [18 ] A vnir, D., Kaufm an, V. R. and R eisfeld, R., J. N on2c rysṫ So lids, 74, 395 (1985)

7 96 Chem ical R esearch in Ch inese U niversities V o l. 15 (Κ= nm ). T he X2ray pow der diffraction data w ere m easu red on it u sing KC l as the inner standard at a scann ing rate of (1g8) m in - 1. A H itach i X2650B scann ing electron m icro scope w as u sed to ob serve the particle size and mo rpho logy of the p roducṫ T he compo sitional analysis w as perfo rm ed on a Baivd PS23 induction coup led p lasm a em ission spectrom eter. T he UV 2V is diffu se reflectance spectrum w as reco rded on a UV UV 2 V is2n IR reco rding spectrom eter u sing BaSO 4 pellet techn ique. Results and D iscuss ion 1 Syn thesis of CoAPO -11 T he gel compo sition and crystallization condition s of CoA PO 211 in the p resence of E t2n H o r i2p r2n H as a temp lating agen t are listed in T ab le 1. It indicates that the amoun t of cobalt is an impo rtan t facto r that affects the crystallization of the p roduct. T he purity of the p roduct decreased w ith increasing the mo lar ratio of cobalt to alum in ium, w h ich w as show n by the XRD pattern s. T he su itab le ratio of CoO to A l2o 3 fo r syn thesizing pure CoA PO 211 mo lecu lar sieve w as less than 012. W ith a h igher CoO ga l2o 3 value, amo rphou s p roduct fo rm ed. Fo r syn thesizing pure CoA PO 211, the favo rab le temperatu re ranged from 180 to 200. A t low er temperatu res, it w as difficu lt to ob tain the crystal, w h ile at h igher temperatu res, it easily resu lts in the fo rm ation of A lpo 42tridym ite. T he effect of reaction tim e on syn thesizing pure CoA PO 211 w as investigated and the su itab le reaction tim e w as found to be 12_ 16 days. 3 N o. T able 1 T yp ical gel compo sitions and crystallization conditions fo r the synthesis of CoA PO 211 mo lecular sieve 3 Compo sition in gel n (CoO ) n (P2O 5) n temp late n (EG) tg tgd P roduct Et2N H CoA PO E t2n H CoA PO 211+ Am E t2n H CoA PO 211+ Am Et2N H CoA PO E t2n H CoA PO 211+ Am E t2n H CoA PO 211+ Am Et2N H CoA PO Et2N H CoA PO E t2n H CoA PO 211+ Am i2P r2n H CoA PO i2P r2n H CoA PO 211+ Am i2P r2n H CoA PO i2P r2n H CoA PO i2P r2n H CoA PO 211+ Am i2P r2n H CoA PO i2P r2n H CoA PO 211+ Am i2P r2n H CoA PO 211 Gel compo sition is based on n (A l2o 3) = Am deno tes amo rphous p roducṫ Fo r comparison, triethylene glyco l ( T EG ) w as u sed as a so lven t fo r syn thesizing CoA PO 211, and a pow der p roduct of CoA PO 211 w as ob tained. How ever, no m atter how the reaction condition s w ere changed, there w as alw ays som e amo rphou s phase in the p roduct and pure CoA PO 211 cou ld no t fo rm. It seem s that the so lven t p layed an impo rtan t ro le in the crysta lliza t ion of CoA PO 211, w h ich m igh t be resu lted from the po la r and the d ifferen t

8 98 Chem ical R esearch in Ch inese U niversities V o l. 15 Co 2+, w h ich is balanced by the p ro tonated o rgan ic am ine occluded in the open2fram ew o rk of the mo lecu lar sieve. T he scann ing electron m icrograph s of as2p repared CoA PO 211 co rresponding to N o s. 10, 13 and 17 in T ab le 1 a re show n in F ig. 2. It revea ls tha t the p roduct w a s p u re and homogenou s in particle size. U nder variou s reaction condition s, the crystal particles had differen t sizes from 5 to 40 Λm and differen t mo rpho logies, such as rhom bu s, sp indle2like mo rpho logy w ith a h igh agglom eration and p rism single crystal. It seem s that the reactan t compo sition and reaction temperatu re greatly affected bo th mo rpho logy and particle size of CoA PO 211 pow der. W h ile E t2n H w as u sed as the temp late, the crystal particles had a h igh agglom eration w ith sphere2like mo rpho logy and differen t sizes from 5 to 60 Λm. T he resu lt reveals that the temp late greatly affected the nucleation and grain grow th th rough the reaction p rocedu re. F ig. 2 Scanning electron m icrograph s of as2p repared CoA PO 211. F ig. 3a g ives the d iffu se reflectance sp ect rum of the p roduct. It show s a st rong t rip let p eak a t 542, 580 and 624 nm. A cco rding to Co tton et a l., th is is the characteristic of tetrahedrally coo rdinated Co ( g ) w ith a d 7 configu ration [13 ] and greatly differen t from the pen ta2coo rdinated [14 ] and octahedrally coo rdinated Co ( g ) [15 ]. T he th ree m ax im a at 542, 580 and 624 nm are cau sed by J ahn2t eller d isto rt ion andgo r by sp in2o rb it coup ling du ring the sp in2allow ed 4 A 2 4 T 1 tran sition. Compared to that of as2 a, b, c co rresponding to N o s. 10, 13, 17 respectively in Table 1. F ig. 3 UV 2V is spectra of as2synthesized p roduct (a) and Co (A c) 2 (b). p repared CoA PO 211, the UV 2V is spectrum of cobalt acetate (F ig. 3b) is b roader and can no t show the fine structu re w ith the th ree distinct m ax im a. T herefo re, the DR S spectrum indicates a tetrahedral coo rdination of Co (g ) in the lattice of A lpo 4211 mo lecu lar sieves. T he b righ t b lue co lo r of the samp le also confirm s th is po in t. Conclus ion s CoA PO 211 mo lecu lar sieve has been hydro therm ally syn thesized from an alcoho l