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samuhu

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[交流] [求助]关于合成NAY型分子筛的导向剂问题

最近在做NAY型分子筛的时候，出现了一个问题：导向剂的制备过程中出现导常现象。
现简单介绍下导向剂的制备过程：
1、制作25#标准水玻璃（SiO2：250g/l Na2O:88g/l）
2、制作偏铝酸钠（Al2O3:42.5g/l Na2O:283g/l）
3、量取300ML 标准水玻璃置于斜圆底烧瓶，并搅拌
4、量取200ML偏铝酸钠溶液缓慢加入到同一圆底烧瓶中
5、搅拌30分钟
6、把混合液置于32度恒温水浴中，老化16小时。

配方的合成分比例为：SiO2：Al2O3：Na2O：H2O=15：1：16：319（mol比）

正常情况下：在第五步过程中，溶液呈透明状态，在老化第2-3个小时，开始出现乳白色胶体，16小时后，胶体变稠。

现在的情况：在第五步的过程中，第三分钟后，溶液迅速变胶（非常稠，甚至成块状）

为了解决此问题，我是这样做的：
1、换水玻璃（没成效）
2、重新制作偏铝酸钠（无成效）
3、冷却水玻璃，偏铝酸钠（怀疑环境温度升高，无成效）

现在想向兄弟们请教：

1、兄弟们在做Y型分子筛导向剂的时候，在制作是个什么的现象？
2、能否提供你们做导向剂的方法？

回复此楼

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1楼 2008-05-31 20:13:38

已阅回复此楼关注TA 给TA发消息送TA红花 TA的回帖

dj_king

铁杆木虫 (著名写手)

应助: 9 (幼儿园)
金币: 13018.2
散金: 780
红花: 3
帖子: 2260
在线: 190.6小时
虫号: 497723
注册: 2008-02-02
性别: GG
专业: 污染控制化学

★ ★
samuhu(金币+2,VIP+0):谢谢，最想知道的是，你在做导向剂的时候，在搅拌过程中会不会产生乳白色胶体。

FAU
Linde Type Y
Si(71), Al(29)

Contributed by David Ginter

Verified by G. Price andby C. Kuntz

Type Material Na56[Al56Si136O384] : 250 H2O

Method D. M. Ginter, A. T. Bell and C. J. Radke [1]

Batch Compositiona

Seed Gel (5% of Al): 10.67 Na2O : Al2O3 :10 SiO2 : 180 H2O
Feed Stock Gel (95% of Al): 4.30 Na2O : Al2O3 : 10 SiO2:180 H2O
Overall Gel: 4.62 Na2O : Al2O3 : 10 SiO2 : 180 H2O

Source Materials

deionized water
sodium aluminate solid (Strem Chemicalb 1.27 Na/Al, 6.1% H2O)
sodium hydroxide pellets (J. T.Baker, 99% NaOH)
sodium silicate solution (PQ Corp, N Brand, 28.7 wt% SiO2, 8.9 wt% Na2O)c

Batch Preparation (for 32 g anhydrous product)

Seed Gel

(1) [19.95 g water + 4.07 g sodium hydroxide + 2.09 g sodium aluminate], stir in 50 mL plastic bottle until dissolved
(2) ((1) + 22.72 g sodium silicate solution], stir moderately for at least 10 minutes; after stirring, cap the bottle and let the solution age at room temperature for 1 dayd

Feedstock Gele

(3) [130.97 g water + 0.14 g sodium hydroxide + 13.09 g sodium aluminate], stir in a 500 mL plastic beaker until dissolved
(4) [(3) 142.43 g sodium silicate solution], stir vigorously with a high-shear turbine mixerf until the gel appears somewhat smooth; cover the beaker until the addition of the seed gel

Overall Gel

(5) [(4) + 16.50 g of (2)], slowly add seed gel (2) to feedstock gel (4) under high shear;f move the beaker during mixing to ensure the entire gel volume encounters the high shear from the turbine (up to 20 minutes)g

Crystallization

Vessel: 300 mL polypropylene bottle (sealed)
Incubation: One day at room temperature g Temperature: 1000C g
Time: After about 5 h, the gel will separate into a solid (containing the NaY Zeolite) that will settle to the bottom, and a hazy supernatant liquid. Continue heating until the supernatant is clear indicating complete crystallization (no more than 2 additional hours)g

Product Recovery

(1) Centrifuge; decant supernatant
(2) Filter the wet solid product; wash with distilled water until pH of filtrate is below 9
(3) Dry at ll0¡C
(4) Yield: approximately 32 g of anhydrous NaY (about 98% on Al2O3)

Product Characterization

XRD FAU; characteristic strong reflections at d = 14.28, 8.75 and 7.46 Å, a0 = 24.72 Å.
Competing phases (if present): GIS, GME, CHA
Elemental Analysis; NaAlO2. 2.43 SiO2
Crystal Size and Habit: octahedral crystals, <1 um
Click here to view XRD pattern

References

[1] D. M. Ginter, A. T. Bell, C. J. Radke, in Synthesis of Microporous Materials, Vol. 1, Molecular Sieves, M. L Occelli, H. E Robson (eds.), Van Nostrand Reinhold, New York, 1992, p 6
[2] T. Linder, C. Kurtz, personal communications

Notes

a. This procedure is reliable only for the production of submicron NaY crystals and is limited in the range of sizes and compositions that can be produced using slight procedural modifications.

b. Also available as solutions with this Na/Al ratio from Alcoa and U. S. Aluminate.

c. It should be clear of precipitated material.

d. Solution is clear when prepared; during aging, a loose gel forms which contains the NaY seeds.

e. May be prepared concurrently with the seed gel or just prior to mixing the overall gel.

f. 1600 rpm with 2.5 inch diameter, 4 paddle radial mixer (minimum) recommended.

g. If a GIS (NaP) impurity is produced, it can be eliminated by reducing the Na aluminate in (1) to 1.40 g and aging the seed gel for 1 to 5 days prior to blending it into the feedstock. Further aging of the composite is optional with this seed, and pure product has been obtained after crystallization at 900C for 22 hours [2]