|
AFI |
CoAPO-5 |
P(51), Al(45), Co(4) |
Contributed by Myriam Uytterhoeven and An Verberckmoes
Verified by S. Ashtekar, by P. Norby, by J. Jänchen, and by H. van Breukelen
Type Material [CoAl11P12O48]: wH2O (w = 0.1 to 0.2)
Method M. G. Uytterhoeven, R A. Schoonheydt [1, 2]
Batch Composition 0.7 TriEA: (Co0.08Al0.92P)O4: 20 H2O
Source Materials
water (doubly distilled)
phosphoric acid (Janssen Chimica, 85% H3PO4)
cobalt nitrate, Co(NO3)2. 6 H2O (Janssen Chimica)
pseudoboebmite (Catapal, Vista, 70% Al2O3
triethylamine (TriEA) (Janssen Chimica 99%)
Batch Preparation (for 27 g product)
(1) [62.6 g water + 23.06 g phosphoric acid], mix; chill to 0¡C
(2) [(1) + 4.66 g cobalt nitrate], stir until dissolved
(3) [(2) + 13.4 g pseudoboehmite], add alumina under continuous stirring
(4) [(3) + 14.3 g TriEA], add amine under continuous stirring;a stir for one additional hour. Initial pH ~3
Crystallization
Vessel: stirred, Teflon-lined autoclave
Temperature: 200¡C
Time: 24 hours
Agitation: Stirring is essential.b Autoclaves were "tumbled" (end-over-end) in the oven
Product Recovery
(1) Filter and wash with distilled water; dry at room temperature
(2) Yield: near 100% on T-atom basis
Product Characterization
XRD: pure AFI, CHA impurity when present is evidenced by a line at 9.5¡(2q )c
Elemental Analysis: 0.10 TriEA. (Co0.086Al0.892P1.000O4) .0.13 H2Od
Crystal Size and Habit: agglomerates formed by hexagonal platelets,
regularly shaped (spherical or diabolo-shaped) with dia. = 55 um e,f
Click here to view XRD pattern
References
[1] M. G. Uytterhoeven, R. A. Schoonheydt, Micropor. Mater. 3 (1994) 265
[2] M. G. Uytterhoeven, R. A. Schoonheydt, Proc. Ninth Int. Zeo. Conf., R von Ballmoos, J. B. Higgins, M. M. J. Treacy (eds.), Butterworth-Heinemann, Boston, 1993, p. 329
Notes
a. TriEA addition causes an exothermic reaction; the preparation should be performed at 0¡ C and TriEA added drop by drop under careful temperature control.
b. Under static conditions, co-crystallization of CHA is more probable.
c. The co-crystallization of CHA can be suppressed by reducing the amine content and/or decreasing the cobalt content. The latter requires an increase of the Al content so that [Al + Co = P].
d. On T-atom basis, the product composition is almost equal to the gel composition. Al + Co = P should be approximately achieved.
e. SEM is suited to distinguish between AFT and much smaller CHA crystals.
f. At low cobalt content (e.g., Co0.02Al0.98P1.00), single crystals are formed, shaped as hexagonal bars. Twinning can occur. Increasing cobalt content causes agglomeration giving larger, regular agglomerates. At high cobalt content (for example, Co0.08Al0.92P1.00) single crystal formation can be achieved by increasing dilution and increasing template content, although the latter favors the co-crystallization of CHA.