BEA

[Ti,Al] Beta

Si(95), Ti(3), Al(2)

Contributed by Dilson Cardoso

Verified by M. Camblor and by W. S. Ahn

Type Material (TEA) 1.5[Ti2.0Al1.5Si60.5O128] (TEA = tetraethylammonium)

Method S. Jahn, D. Cardoso [1,3], M. A. Camblor, A. Corma, J. Pérez-Pariente [2]

Batch Composition 0.033 TiO2 : SiO2 : 0.0026 A12O3 : 0.269 (TEA)2O : 15.5 H2O

Source Materials

tetraethylammonium hydroxide (Aldrich, 35% TEA-OH aqueous solution)
tetraethylorthotitanate (Aldrich, 99%)
silica (Degussa Aerosil 380, 99+%)
aluminum nitrate (Al(NO3)3 9 H2O) deionized water

Batch Preparation (for ~1 g product)

(1) [13.24 g tetraethylammonium hydroxide solution + 0.44 g tetraethylortho-titanate], mix in a glove box; stir for 10 minutes a
(2) [(1) + 3.52 g silica], stir for 15 minutes
(3) [0.11 g aluminum nitrate + 7.69 g water], stir until dissolved
(4) [(3) + (2)], stir until homogenized (10 minutes minimum) b

Crystallization

Vessel: 50 mL stainless steel autoclave with Teflon liner
Time: 60-96 hours
Temperature: 1400C
Agitation: optional
Final pH: ~12.5

Product Recovery

(1) Quench autoclave in cold water
(2) Centrifuge (7000 rpm) and wash until pH is about 9
(3) Dry overnight at 800C
(4) Yield: 3-4 g/100 g batch (about 90% based on Al, 40% on Ti and 25% on Si)

Product Characterization

XRD: zeolite beta (no other phases)
Elemental analyses: Ti2.0Al1.5Si60.5O128 (for material with 96 hours crystallization. As synthesized material contains TEA+ cations)
Crystal size and habit: round-shaped particles with average size 0.28 um (for 96 hours crystallization) and a narrow size distribution
Click here to view XRD pattern

References

[1] S. L Jahn, P. A. P. Nascente, D. Cardoso, Zeolites 19 (1997) 416
[2] M. A. Camblor, A. Corma, J. Pérez-Pariente, Zeolites 13 (1993) 82
[3] S. L Jahn, D. Cardoso, in Proceedings of 12th International Zeolite Conference, Vol. III, M. M. J. Treacy, B. K. Marcus, M. F. Bisher, J. B. Higgins (eds.), Materials Research Soc., Warrendale, PA, USA (1998), pp 1885-1892,

Notes

a Tetraethylorthotitanate hydrolyses very rapidly under normal atmospheric conditions forming extra framework TiO2. Using this Ti-source, the gel must be prepared in a glove box.

If this equipment is not available, the gel can be prepared under normal atmosphere using a solution of tetraethylortho-titanate in isopropyl alcohol (TEOTi/iPrOH molar ratio of 1/10). This results in a small loss in solid yield.

b. It is difficult to synthesize the beta structure in total absence of aluminum. This recipe employs the minimum content of this element (Si/Al ~400).

c. The solid particles formed during synthesis are very small, and it is very difficult to filter them. Unfortunately the appropriate method for purification is by centrifugation.