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AEI |
SAPO-18 (TEA method) |
P(50), Al(48), Si(02) |
Contributed by Rune Wendelbo
Verified by E Dumitriu and by C. Round
Type Material [Al23.2 SiO0.8 P24O96] b
Method: R Wendelbo, D. Akporiaye, A. Andersen, I. M. Dahl, H. B. Mostad [1]
Batch Composition Al2O3: 0.98 P2O5: 0.015 HCl: 0.075 SiO2: (TEA)2O: 70 H2O : 2.8 i-C3H7OH c (TEA = tetraethylammonium)
Source Materials
distilled water
aluminum isopropoxide (Jansen, 98+%)
phosphoric acid (85%)
hydrochloric acid (3 7%)
silica sol (DuPont Ludox LS-30, 30% Si02)
tetraethylammonium hydroxide (Aldrich, 40 % (TEA)OH) d
Batch Preparation: (for 13.8 g dry product)
(1) [108 g water + 81.6 g aluminum isopropoxide], mix in a one liter poly-propylene bottle and shake for 1 minute
(2) [(1) + 45 g phosphoric acid], shake for 1 minute then cool under running tap water
(3) [(2) + 0.6 g hydrochloric acid], shake bottle e
(4) [(3) + 3.0 g silica sol], shake bottle. filter gel for 10 minutes (water suction).
About 100 g filtrate is removed and discarded. Transfer one-third of filter cake gel to a 250 mL plastic bottle
(5) [One-third (4) + 49 g tetraethylammonium hydroxide solution], shake
Crystallization
Vessel: 200 mL stainless steel, Teflon-lined autoclave (Berghof)
Incubation: 12 hours at room temperature
Time: 120 hours
Temp: 2150C
Agitation: gentle f
Product Recovery
(1) Recover solid product by centrifugation. g
(2) Wash once with distilled water; recover product by centrifugation g
(3) Dry overnight at 1000C
(4) Calcine for 4 hours at 5500C in flowing, dry air
(5) Store under nitrogen. Yield near 100%
Product Characterization
XRD: fully crystalline AEI; competing phase AFI and CHA h
Elemental Analyses: 0.84% Si, 19.9% Al, 26.6% P i
Crystal size and habit: square platelets, 0.1-2.0 um x 0.1 um thick j
Click here to view XRD pattern
Reference
[1] R Wendelbo, D. Akporiaye, A. Andersen, I. M Dahl, H. B. Mostad, Appi. Catal. A: General 142 (1996) L197
Notes
a. Mg AIPO-18 and Zn APO-18 were synthesized like SAPO-18 by using Mg and Zn nitrates in place of colloidal silica in equivalent amounts on a molar basis. The Mg and Zn nitrates were dissolved in the phosphoric acid 20 m prior to mixing with the other reagents. Products showed 0.14 Mg and 0.10 Zn (nmol/g).
b. Based on Si content; excess P is unexplained.
c. It is assumed that water, HC1 and isopropanol are lost in equal proportions and no other components are lost in gel filtration.
d. This product is now traded as 35% (TEA)OH solution. I would use the same volume of the 35% solution, since the synthesis is not sensitive to a variation of the template concentration of this order. It is important that the (TEA)OH source have minimum K+ and Na+ concentrations.
e. Addition of HCl has previously been found to allow better control of Si substitution in SAPO-34 and has been used in this case for the same purpose.
f. Standing autoclaves in a heated block on a "shaking table" rotated at about 60 rpm.
g. Filtration leads to loss of fine material or goes very slowly depending on the filter.
h. At lower water content, AFI appears as a contaminant; at higher water content, CHA appears.
i. Analysis by XRF.
j. Micropore volume 0.25 mL/g (by N2 sorption)