Synthesis and structure of an ABW type thallium aluminosilicate

Synthesis and structure thallium aluminosilicate

of an ABW type

I.G. Krogh Andersen and E. Krogh Andersen Chemical Institute, Odense University, Odense, Denmark P. Norby* Department

of Chemistry, University

C. Colella Dipartimento di Chimica, Ingeperia di Roio, L’Aquila, Italy

of Oslo, Oslo, Nomay

Chimica e Materiali,

M. de’Gennaro Dipartimento di Scienze della Terra, Napoli,

L’Aquila

University,

Monteluco

Italy

TIABW, TIAISi04 was prepared hydrothermally in presence of Li+, Na+, and K+ ions, and its structure was determined from X-ray powder diffraction data. The unit cell is a = 8.297 (l), b = 9.417 (I), c = 5.413 (1) A, and the space group is PnaP,, No. 33, Z = 4. The structure was refined using powder diffraction data by the Rietveld profile refinement technique. The anion framework has an ordered S/AI distribution. The extraframework cations (TI+) occupy three partially populated positions. The structure is described, and the synthesis of TIABW in presence of lithium, sodium, or potassium ions is discussed. Keywords:

Thallium;

zeolites;

ABW;

synthesis;

structure

INTRODUCTION Taylor’ reported results of preparations of aluminosilicates from alumina and silica gels containing thallium hydroxide. Barrer et al.’ prepared aluminosilicates from metakaolinite and thallium hydroxide. In both investigations, the materials were crystallized under hydrothermal conditions (the former at 22O”C, the latter at 80°C). Several crystalline phases were obtained in these studies, none of them, however, pure. One of Taylor’s specimens, by him called Tl-B, has a composition in reasonable agreement with the formula TlAlSiO+ One of Barrer et al.‘s specimens, by them called TI-C, has an X-ray powder diagram in close agreement with the powder diagram reported for Taylor’s Tl-B material. We have prepared a thallium aluminosilicate that shows an X-ray powder diagram in agreement with the powder diagrams of Taylor and Barrer et al.‘s Tl materials. Chemical analyses show that the material has the chemical composition: TlAlSi04. Structure determination by X-ray powder diffractometry has * Present

address:

Chemical

Institute,

Odense

University,

DK-

5230 Odense M, Denmark. Address Institute, Received

reprint requests to Dr. Krogh Odense University, DK-5230 23 October 1989; accepted

0 1991 Butterworth-Heinemann

Andersen at the Chemical Odense M, Denmark. 11 December 1989

shown that the material is of zeolite structure type ABW.3 Hence, the material is called TlABW in the following. The hydrothermal preparation of zeolite LiA(BW) (LiA1Si04, H20) was reported by Barrer and White in 1951.4 The structure was determined by Kerr.5 The structure was later redetermined by X-ray singlecrystal data6 and by neutron diffraction data obtained from powder.’ All the structure determinations are in agreement (within their stated estimated standard deviations). The ABW framework structure of zeolite LiA(BW) is orthorhombic. It may be seen as built of four-membered rings of Si04 and AlO tetrahedra connected to bands running in the c axis direction. Single four units of such bands are, as shown in Figure 4a, connected to form the 8-ring channels. If the distribution of Si and Al atoms on the available sites were random, the maximum symmetry the anion framework can achieve is Imam. Because of the ordering of the Si and Al tetrahedra, the true symmetry is, however, the lower Pna2l. In zeolite LiA(BW), the extra framework cations (Li+) are four-coordinated by three framework-oxygen atoms and one water molecule. It is renorted in the literatures-” that the ABW anion fra’mework can accommodate the larger ions Rb+ and Cs+, but, then, water is excluded. Here, we

ZEOLITES,

1991, Vol 11, February

149

Synthesis Table weight

of an ABW

of thallium

aluminosilicate:

1 Chemical analyses for TIABW % and molar ratio R (Al,03 = 1) Sample Wt%

SiOz 403 T120 L&O Na,O W

type

19.00 16.40 63.92 0.25 -

1 I? 1.96 1.00 0.93 0.05 -

Sample Wt% 19.10 16.26 64.20 0.38 -

samples;

2 R 2.00 1.00 0.95 0.04

repoit the synthesis, chemical composition, ture of TIABW.

LG.

Krogh

figures

are

Sample

Wt%

3 I?

18.20 15.56 65.50 0.30

1.98 1 .oo 1.01 0.02

and struc-

EXPERIMENTAL Synthesis runs were performed at 200°C at autogenous pressure in sealed Teflon containers, rotated for programmed times in a thermostatted oven. Particular care was taken in avoiding contact of the reaction magma with atmospheric carbon dioxide. The following reagent grade chemicals were used for preparing the reaction mixtures: silica suspension (Ludox, 40%’ SiO?), dried aluminium hydroxide (Serva, 61.35% Al.,O:%), TIZSO., (Fluka), and LiOH.H20 (Merck). Based on the synthesis conditions previously found,” the oxide batch composition for TlABW crystallization is as follows: 1.4 Me20.2. 1 T120.A1.,0:~.2 Si02. 100 HZ0 where Me is Li, Na, or K. At the end of the reaction, the products were separated from the mother liquors by filtration, washed, and dried overnight at 100°C. Curves showing the progress of crystallization of TlABW were obtained by estimating the crystallinity of samples extracted from the reaction mixture during syntheses. As a measure of crystallinity, the integrated intensity of selected diffraction peaks was used. The chosen reference as 100% crystallinity was the well-crystallized product obtained from the reaction involving potassium after 5 d (Sample 3, Table 1). Electron microscope examination of the samples was performed on Au-coated products, using a Cambridge Stereoscan 250 TP apparatus. Chemical analyses have been made using standard procedures: Si and Al have been determined gravimetrically: Tl, Li, Na, and K by atomic absorption spectrophotometry (Perkin-Elmer 370).

X-ray

et al.

Table2 The with powder

indexed patterns

X-ray powder pattern ofTlA8Wcompared ofTI-B (Taylor') and TI-C (Barrer

TIABW

TI-B (Taylor) dabs

ZEOLITES,

1997, Vol I I, February

TI-C (Barrer eta/.) dDbs I

d ohs

hkl

I

6.215 4.700 4.683 4.142' 3.260 3.108 3.103

6.221

110 020 1 011 200 121 220 r 211 ?I*03 130

4

6.5

VW

6.15

w

10 5 10

4.81 4.24 3.31

ms VW ms

4.62 4.09 3.23

vs m ms

20 1 8

3.11

s

3.08

vs

2.96

mw

2.93 2.90 2.83

mw w mw

2.71

m

2.68

ms

2.36 2.28 2.19 2.09

VW w VW m

2.24 2.15 2.07

mw w w

1.985

mw

2.05 2.02 1.97

mw w mw

1.890 1.840 1.780

mw w vvw

1.87 1.81 1.76

mw VW VW

1.705

mw

1.68 1.66

w w

1.645 1.625

mw

1.63

w

VW

1.555 1.520 1.500

VW VW vvw

2 1 1

1.465

vvw

1.415

vvw

3

1.355

VW

1.340

VW

1.285 1.270

VW VW

1.240

VW

1.225

VW

1.130 1.100

VW vvw

4.689 4.143 3.261 3.105 3.038 2.931

2.931

2.710 2.701 2.650 2.342 2.262 2.179 2.086 2.072 2.071 I 2.038 1.986 1.894 1.891 1.834. 1.776 1.768 1.699 1.634 1.644 1.626 1.561 1.551 1.517 1.501 1.481 1.465 1.465 1.436' 1.408 1.350 1.347 1.345 1 1.324 1.321 1.314' 1.288) 1.2881 1.270 1.243 1.243 I 1.238 1.229 1.131 1.130

2.705 2.650 2.342 2.264 2.179 2.086 2.072 2.039 1.986 1.893 1.834 1.777 1.769 1.699

1.644 1.627 1.561 1.552 1.517 1.501 1.480 1.465 1.436 1.409 1.348

1.323 1.314 1.288 1.270 1.243 1.239 1.229 1.130

301 002 310 022 202 321 141 330 400 ‘222 132 411 312 150 051 013 341

8 3 6 8 2 1 1 10

402 332 213 033 422 152 521 161 530 260 323 143 004 352 1 413 611 { 361 541 262 { 532 343 271 550 ‘224 602 404 280

specimen Tl-C.” listed in Table 3.

al.‘s

X-ray powder

I

eta/.‘)

d dF

3 1 6 3

diffraction

The material was characterized by X-ray powder diffractometry. A Guinier-Hsgg diagram (CuKarl = 1.54051 A (Ref. 12), internal standard quartz, lattice constants a = 4.9 1309 A, c = 5.40426 A (Ref. 13)) was indexed, and lattice parameters were refined by least-squares program PARAM.‘” In Table 2, the lattice spacings found for TlABW are compared with spacings of Taylor’s specimen Tl-B’ and Barrer et

150

Andersen

The

unit cell parameters

are

diffraction

X-ray powder diffraction

profiles

of TlABW

(Sam-

Synthesis Table 3 Lattice materials with

constants in A, unit cell ABW structure (numbers

volumes in A”, and framework in parentheses are standard

a LiA(BW) TIABW TIABW RbABW CsABW

sample sample

b

10.313(l) 8.297(l) 8.287( I) 8.741 8.907(2)

1 3

of an ABW

8.194(l) 9.417(l) 9.396(l) 9.226 9.435(l)

X

Al Si O(1)

T!(3)

2043(10) 3154(10) 3(10) 2814(20) 2718(10) 2761(10) -117(4) -1913(20) -9333(20)

R R R R

on on on on

O(2) O(3) O(4) TI(l)

TU)

index index index index

Y 710(10) 4140(10) 651(10) 2440(10) 9513(20) 10117(20) 6906(2) 7317(20) 6870(10)

densities deviations)

aluminosilicate:

FD (number

LG. Krogh

of tetrrahedral

V

4.993(l) 5.413(l) 5.404(l) 5.337 5.435(l)

Determination of the cation positions and refinement of the structure All calculations were made with the XRS-82 program.15 The similarity of the unit cell to that of Rb- and Cs-ABW lead to the assumption that the anion lattice was of ABW-structure type. The coordinates of the framework atoms (from RbABW) were geometrically refined (DALS program) in the unit cell found for TlABW. In these refinements, the space group Pna21 was used and it was assumed that the Si/Al distribution was ordered (i.e., Si-0 distance 1.6 1 A and Al-O distance 1.75 A). Then, a difference Fourier map was calculated. From this, the positions of the thallium ions were found. Three partially occupied positions were detected. Thallium atoms at these positions were now included in the model with population factors constrained so that their sum was in agreement with the cell content calculated from the chemical analysis. In difference maps calculated at this stage, no other significant peaks could be observed. The structure was refined using the

(x

of thallium

C

ple 1, Table I) were recorded with a Siemens D500 diffractometer using CuKal radiation monochromatized by a primary Ge-monochromator. The 28 range covered was from 4 to 106”. The step length was 0.02” in 28, and maximum counting time for each step was 60 s. The data were corrected for background, and a peak shape function was calculated from the observed profile of the 121 reflection (28 = 27.4”). This was done by the program STEPCO and PEAK included in the X-ray Rietveld System XRS-82.”

Table 4 Final atomic coordinates parameters B (A’) and population listed below)

type

Andersen

atoms

per

1000

FD

421.93 420.80 420.78 430.40 457.00

19.0 19.0 19.0 18.6 17.5

et al. A3) in

Ref.

This This

6 investigation investigation 8 9

CRYLSP program. In the refinement, the geometrical restrictions were released gradually. In the final cycles of CRYLSP calculations positional parameters for all atoms and population parameters for thallium ions were refined without constraints. In addition, peak asymmetry, peak half-width, and cell parameters were refined. The final atomic coordinates and other structure parameters are listed in Table 4. The obtained R values are also recorded in this table. In Figure 1, the observed and calculated diffraction profiles and their difference are shown. RESULTS Synthesis runs, performed uncler the conditions referred to in the experimental section, always resulted in crystallization of TlABW. Table I reports the results of the chemical analyses of three samples of the thallium aluminosilicate, obtained from systems containing Li+, Na+, or K+, respectively. If the small amounts of alkalimetal cations in the three samples are disregarded, the chemical analyses are consistent with the formula TlAlSiO.,. Figure 2 shows the progress of crystallization during synthesis. The crystallization rate is higher for systems with Li+ or K+ than for systems where Na+ is present. A temporary co-crystallization of another phase, pre-

IO? isotropic temperature parameters fr, (R values are

z 2500 2487(20) 2476(30) 2887(30) 4796(20) -399(20) 2636(2) 1956(40) 2343(50)

structure factors R(F) = 0.058 intensity values R(I) = 0.078 profile R(P) = 0.095 weighted profile R(wP) = 0.096

B 1.1(4) 4.0(5) 1.6(3) 0.7(5) 2.7(1.2) 4.7(1.3) 1.1(l) 5.0(5) 3.3(2)

PP 1.0 1.0 1.0 1.0 1.0 1.0 0.68 0.20 0.22

-:i 20

Figure 1 Observed, calculated, for TIAISi04, TIABW

ZEOLITES,

and difference

diffraction

7991, Vol 7 1, February

profiles

151

Synthesis

of an ABW

type

of thallium

aluminosilicate:

2

1

Figure 2 Increase of crystailinity 200°C from thallium aluminosilicate K (01, or Na (0)

of TIABW systems

LG. Krogh

Andersen

et al.

567

during synthesis containing Li

at

(A),

sumably of edingtonite type,” was frequently observed during the early stages of crystallization. it is noted that TlABW is unstable in the presence of lithium. It gradually changes into a cancrinite-type phase, in agreement with the observations made on zeolite synthesis in the presence of the cation couple Tl, Li. I1 Figures 3a, b, and c show the prismatic shape of TlABW crystals. They are very stable on heating. They remain unchanged until lOOO”C, when a breakdown occurs.

Lattice

constants

The lattice constants of TlABW are given in Tuble 3 and are there compared with values for LiA(BW) hydrate, RbA1Si04, and CsA1Si04. It is seen that although the a axis is longer than the b axis in LiA(BW), the reverse is the case in the thallium, rubidium, and cesium compounds. The main reason for that is the large radii of the Tl+, Rb+, and Cs+ ions. In LiA(BW), the water molecules situated on the line between the lithium ions release the Coulombic interaction between neighbor cations. In the Tl, Rb, and Cs compounds, there are no water molecules; hence, the electrostatic interaction increases. This is compensated by the lengthening of the b and c axes. One common feature for the unit cells of Tl-, Cs-, and RbABW is the flratio between the b and c axes. This reflects the pseudohexagonal nature of the b, c plane for the expanded ABW framework (Figure 4~).

Description

ZEOLITES,

3 Scanning electron from thallium-silicate

micrographs systems

of TIABW crystals, containing Li (a), Na (b),

of the structure

The TlABW structure is shown in Figure 46 and c. The general description of the ABW anion lattice was given in the Introduction. The average Al-O and Si-0 distances are in favor of a. structure with ordered %/Al distribution. It has been shown by Norby and Jakobsen” that the *‘Si MAS n.m.r. spectrum of TlABW contains only one line. This is clear evidence of an ordered arrangement. The average Al-O distance and the average

152

Figure obtained K (cl

7997, Vol 7 1, February

Si-0 distance are within their accuracy in agreement with commonly accepted values for these bonds (see Table

5).

The surroundings

of the thallium

ions

The positions where the thallium ions are located have rather irregular surroundings. The positions are indicated in Figure 46. The thallium to oxygen

Synthesis

of an ABW

type

of thallium

aluminosilicate:

LG. Krogh

Andersen

et al.

Figure 4 (a) The ABW framework (as found in zeolite LiA(BW) projected along the (001) direction (b) The TIABW framework projected along the (001) direction (c) The TIABW structure projected along the (100) direction

distances are shown in Table 6. The TI(1) and Tl(2) positions have short distances (~3.5 A) to 8 oxygen atoms, the Tl(3) position only to 7. The distances are in the range 2.33-3.49 A. These values are in agreement with distances commonly found in Tl(IJ compounds. In Tl:,PO.,,“, TIPHPO~,‘“, T1aW04,’ HCOOTl,*’ and T1[B90 i(OH)2] 0.5 H20.*’ the Tl-0

Table sphere

5 Bond distances (A) and angles of aluminum and silicon atoms

(“) in the in TIABW

coordination

AI-O(l) AI-O(2) AI-O(3) AI-O(4) Average

1.69(l) 1.76(l) 1.77(2) 1.77(l) 1.75(4)

O(1 )-AI-O(2) Oil )-AI-O(3) Of1 )-AI-O(4) O(2)-AI-O(3) O(2)-AI-O(4) 0(3tAI-O(4) Average

113(l) 10811) 109(l) 113(l) 106(l) 108(l) llO(3)

%-O(l) Si-O(2) Si-O(3) Si-O(4) Average

1.55(l) 1.64(l) 1.66(2) 1.65(2) 1.63(5)

O(1 )-Si-O(2) Oil )-Si-O(3) Of1 )-Si-O(4) O(2)-Si-O(3) O(2)-Si-O(4) O(3)-Si-O(4) Average

107(l) 113(l) 113(l) 104(l) 112(l) 107(l) 109(4)

distances are in the range 2.46-3.55 shorter distance of 2.38 8, has been general feature in all the mentioned the short distances (those below 2.7 three oxygen atoms for each thallium

A. In TL,Os, a found.” It is a compounds that A) only involve ion.

CONCLUSIONS To obtain TlABW crystallization, the hydroxide ion concentration must be very high. Large concentrations of alkali hydroxides have been used. The constancy of the composition of the products shows that it is unimportant which of the hydroxides, LiOH, NaOH, or KOH, is used. The crystallization rate is dependent on the type of alkalimetal ion present. With Li+ and K+, 100% crystallinity is obtained sooner than when Na+ ions are present. Prolonged reaction time when Li+ ions are present results in transformation of TlABW into Li,TlCAN. The structure of TlAlSi04 is of ABW-type with an ordered Si/Al distribution. The similarity between the thallium cation and the larger cations of rubidium and cesium, which also forms ABW-type aluminosilicates, is reflected in the pseudohexagonal nature of

ZEOLITES,

1991, Vol 11, February

153

Synthesis Table

of an ABW 6 TI-0

type

distances

TI(1 )-O(3)’ TI(l )-O(4)* TI(1 )-O(4)’ TI(1 )-0(2)3 TI(1 )-0(3)4 Tl(l)-0(2)5 TI(1 )_O(2)6 TI(ljO(1)’

of thallium

in TIAEW

aluminosilicate:

LG.

Krogh

Andersen

et al.

in 8,

2.53(l) 2.79(l) 3.06(2) 3.24(2) 3.37(2) 3.46(2) 3.46(2) 3.49(2)

Tl(2)-O(2)6 Tl(2)-O(3)’ Tl(2)-O(4)’ Tl(2)-O(4)’ Tl(2)-O(3)’ Tl(2tO(2)7 Tl(2)-O(1 Tl(2)-O(1)“’

2.33(3) 2.36(3) 2.68(3) 2.85(3) 3.23(3) 3.30(3) 3.44(2) 3.49(2)

)6

Tl(3)-O(4)” Tl(3)-O(2)” Tl(3t0(3)13 Tl(3)-O(3)14 Tl(3)-O(3)15 Tl(3)-O(2)16 Tl(3)-O(4)“’

Superscripts refer to following symmetry operations: 1 :x- ‘12, 1% - y, 2; 2: ‘12 - x, y + %, 2 + %; 3: X-x, y + %, z~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ y-‘l&z+ ‘h; 12:-x-‘/Z, y+ %,z+ l/2; 13:-x-%, y-‘/z,z-‘%; 14: x-l%, I’/2-y,z; 15: x-l, y,z; 16:-x-‘/z,

the b,r plane, which is a consequence of the high degree of expansion in the ABW-framework. However, whereas Rb+ and Cs+ are situated at only one position in the structure, the smaller Tl+ may obtain reasonable oxygen coordination at several positions. Thus, three positions partially occupied by Tl+ were found in TlABW, with approximately 70% of the thallium content in one of the positions.

ACKNOWLEDGEMENTS P.N. wishes to thank the Carlsberg Foundation for financial support. C.C. and M. de’G. thank the Italian Board of Education (Minister0 della Pubblica IstruGone) for financial support.

REFERENCES Taylor, H.F.W. J. Chem. Sot. 1949, 1253 Barrer, R.M., Beaumont, R. and Colella, C. J. Chem. Sot., Dalton Trans. 1974, 934 Meier, W.M. and Olson, D.H. At/as of Zeolite Structure Types, Butterworths, London, 1988, p. 12 Barrer, R.M. and White, E.A.D. J. Chem. Sot. 1951, 1267 Kerr, IS. Z. Krist. 1974, 129, 186 Krogh Andersen, E. and Ploug-Sorensen, G. Z. Krist. 1986, 176, 67

154

ZEOLITES,

1997, Vol 17, February

7

2.43(2) 2.77(3) 2.94(2) 3.07(2) 3.29(2) 3.30(3) 3.39(2)

%; 4: l/z-x, y+

l&z+

y-

l/2, ‘/2.

Norby, P., Norlund Christensen, A. and Krogh Andersen, I.G. Acta Chem. Stand. 1986, A40, 500 8 Klaska, R. and Jarchow, 0. Z’. Krist. 1975,142, 225 9 Gallagher, S.A. and McCarthy, G.Y. J. Mat Res. Bull 1977, 12, 1183 10 Colella, C., de’Gennaro, M. and lorio, V. in New Developments in Zeolire Science and Technology (Eds. Y. Mukarami, A. ljima and J.W. Ward) Kodansha, Tokyo 1986, p. 263 11 Colella, C. and de’Gennaro, M, in Zeolites Synthesis (Eds. M. Occelli and H.E. Robson), ACS Symp. Ser. 398, Am. Chem. Sot., Washington, DC, 1989, p. 196 12 International Tables for X-ray Crystallography, Vol. Ill, Kynoch Press, Birmingham, UK, 1962, p. 69 13 International Tables -for X-ray CrystkVlography, Vol. Ill, Kynoch Press, Birmingham, UK, 1962, p. 122 14 The X-ray 76 System, Tech. Rep. TR-446, Computer Science Center, University of Maryland, College Park, MD 15 Baerlocher. Ch. The XRS-82 Svstem. lnstitut fiir Kristallooraphie und’ Petrographie, ETH,‘Zuri& 16 Norby, P. and Jakobsen, H.J., in preparation 17 Zalkin, A., Templeton, D.H. Eimerl, D. and Velsko, P. Acta Crystallogr. 1986, C42, 1686 18 Oddon, Y., Vignalu, I.-R., Tranquard, A. and PBpe, A. Acra Crystallogr. 1979, 035. 2525 19 Okada, K., Ossaka, J. and Iwai, S. Acta Crystallogr. 1979, 835, 2 189 20 Oddon, Y., Tranquard, A. and Menzen, B.F. Inorg. Chim. Acta. 1981, 48, 129 21 Touboul, M., Bois, C. and Mangen, D.Acta Crystallogr. 1983, C39, 685 22 Marchand, R. and Tournoux, M. CR. Acad. Sci. 1973, C277, 863