Claims
- 1. A method for removing HCl from a gas containing less than about 100 ppm HCl, comprising removing said HCl by contacting said gas with a solid composite adsorbent having surface area greater than about 200 m.sup.2 /g and comprising about 50-95 wt % alumina and about 5-50 wt % Y zeolite, said adsorbent being produced by treating Y zeolite particles with an aqueous acid solution to reduce their sodium silicate content, admixing the acid-treated Y zeolite particles with alumina particles, agglomerating the Y zeolite and alumina particles into a composite agglomerate, aging said agglomerate in the presence of water and activating the composite agglomerate at an elevated temperature.
- 2. The method according to claim 1 wherein the Y zeolite particles have sufficiently low sodium silicate content that a 20 wt % aqueous slurry has a pH of less than about 10.42.
- 3. A composite adsorbent useful for adsorbing gaseous HCl, said adsorbent having surface area greater than about 200 m.sup.2 /g and comprising
- (a) about 50-95 wt % alumina, and
- (b) about 5-50 wt % Y zeolite wherein the molar ratio of SiO.sub.2 to Al.sub.2 O.sub.3 is about 4.5-6.0,
- said adsorbent being produced by admixing particles of alumina with particles of Y zeolite treated with an acid solution so that their sodium silicate content is sufficiently low that a 20 wt % aqueous slurry has a pH of less than about 10.42, agglomerating the alumina and Y zeolite particles into a composite agglomerate, aging said agglomerate in the presence of water and activating said agglomerate at an elevated temperature.
- 4. The adsorbent of claim 3 wherein the alumina particles include activated alumina having an average particle size of about 10 microns or less.
- 5. The adsorbent of claim 4 wherein the molar ratio of SiO.sup.2 to A.sup.2 O.sup.3 in the Y zeolite is about 4.8-6.0.
- 6. The adsorbent of claim 4 comprising about 70-80 wt % alumina and about 20-30 wt % Y zeolite.
- 7. The adsorbent of claim 4 wherein said Y zeolite comprises sodium Y zeolite.
- 8. The adsorbent of claim 4 having a surface area of greater than about 300 m.sup.2 /g and an LOI of less than about 6.0 wt %.
- 9. The adsorbent of claim 3 wherein said acid solution is an aqueous solution of an acid having a pK of about 4-7.
- 10. The adsorbent of claim 9 wherein said acid is acetic acid.
- 11. The adsorbent of claim 3 wherein said composite agglomerate is aged at a pH greater than 7 and at a temperature of about 0.degree.-60 C.
- 12. A method for producing a composite adsorbent useful for adsorbing gaseous HCl, said method comprising
- (a) treating particles of Y zeolite with an aqueous acid solution to reduce the sodium silicate content, said Y zeolite particles having an average particle size of less than about 10 microns,
- (b) sizing alumina to an average particle size of about 10 microns or less,
- (c) agglomerating the alumina particles in the presence of water with the Y zeolite particles, thereby to form a composite agglomerate,
- (d) aging the composite agglomerate in the presence of water at pH greater than 7 to strengthen the agglomerate, and
- (e) activating the composite agglomerate by exposure to an elevated temperature of about 420.degree.-550.degree. C.
- 13. The method according to claim 12 further comprising, prior to step (c)
- (f) rapidly activating the sized alumina particles by exposure to an elevated temperature of
- about 300.degree.-1000.degree. C. for less than one minute, thereby to form activated alumina particles having an LOI of about 6-10 wt %.
- 14. The method according to claim 13 wherein step (a) comprises treating said Y zeolite particles with an aqueous solution of an acid having a pK of about 4-7.
- 15. The method according to claim 14 wherein said acid is acetic acid.
- 16. The method according to claim 14 wherein the Y zeolite particles have an average particle size of about 3-5 microns.
- 17. The method according to claim 14 wherein the molar ratio of SiO.sub.2 to Al.sub.2 O.sub.3 in the Y zeolite is about 4.5-6.0.
- 18. The method according to claim 14 wherein step (c) comprises combining about 50-95 wt % activated alumina with about 5-50 wt % sodium Y zeolite.
- 19. The method according to claim 14 wherein step (d) is performed at a temperature of about 0.degree.-60.degree. C.
- 20. The method according to claim 14 wherein step (e) is performed at a temperature of about 420.degree.-475.degree. C.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part application of U.S. Ser. No. 795,907, filed Nov. 7, 1985.
US Referenced Citations (16)
Foreign Referenced Citations (4)
Number |
Date |
Country |
2923117 |
Dec 1979 |
DEX |
84639 |
Jul 1981 |
JPX |
156913 |
Sep 1984 |
JPX |
1491563 |
Nov 1977 |
GBX |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
795907 |
Nov 1985 |
|