Mesoporous zeolites and methods of making the same
A method of making a mesoporous zeolite may include combining an initial zeolite with cetyltrimethylammonium bromide to form an initial zeolite mixture. The method may also include adding ammonium hexafluorosilicate and ammonium hydroxide to the initial zeolite mixture to form a treated zeolite mixture. The method may also include heating the treated zeolite mixture to form the mesoporous zeolite.
1 . A method of making a mesoporous zeolite, the method comprising:
combining an initial zeolite with cetyltrimethylammonium bromide to form an initial zeolite mixture;
adding ammonium hexafluorosilicate and ammonium hydroxide to the initial zeolite mixture to form a treated zeolite mixture; and
heating the treated zeolite mixture to form the mesoporous zeolite.
2 . The method of claim 1 , wherein the initial zeolite mixture is not exposed to steam prior to forming the treated zeolite mixture.
3 . The method of claim 1 , wherein the method does not comprise one or more of drying, filtering, or calcining the initial zeolite mixture prior to forming the treated zeolite mixture.
4 . The method of claim 1 , wherein the initial zeolite comprises a Y zeolite.
5 . The method of claim 1 , wherein the ammonium hexafluorosilicate and ammonium hydroxide added to the initial zeolite are in an aqueous solution.
6 . The method of claim 5 , wherein the concentration of the ammonium hexafluorosilicate in the aqueous solution is from 0.1 M to 2.0 M.
7 . The method of claim 5 , wherein the concentration of the ammonium hydroxide in the aqueous solution is from 0.01 M to 1.0 M.
8 . The method of claim 1 , wherein the method further comprises combining the ammonium hexafluorosilicate and the ammonium hydroxide before adding them to the initial zeolite mixture.
9 . The method of claim 1 , wherein the ammonium hexafluorosilicate is added to the initial zeolite mixture before the ammonium hydroxide is added; or
the ammonium hydroxide is added to the initial zeolite mixture before the ammonium hexafluorosilicate is added.
10 . The method of claim 1 , wherein nothing is added to the initial zeolite mixture prior to adding the ammonium hexafluorosilicate and the ammonium hydroxide.
11 . The method of claim 1 , wherein the mesoporous zeolite has a total pore volume of at least 0.5 ml/g.
12 . The method of claim 1 , wherein the mesoporous zeolite has a total surface area of at least 650 m 2 /g.
13 . The method of claim 1 , wherein the mesoporous zeolite has a molar ratio of SiO 2 to Al 2 O 3 of from 8.5 to 15.
14 . The method of claim 1 , wherein the mesoporous zeolite comprises less than 0.05 wt. % of Na 2 O.
15 . The method of claim 1 , wherein the heating of the treated zeolite mixture is at a temperature of from 35° C. to 99° C. for from 1 hour to 24 hours.
16 . The method of claim 1 , wherein the ammonium hexafluorosilicate and the ammonium hydroxide are added to the initial zeolite mixture gradually over a period of time from 1 minute to 180 minutes.
17 . The method of claim 1 , further comprising ion-exchanging the initial zeolite prior to the combining of the initial zeolite with cetyltrimethylammonium bromide.
18 . The method of claim 1 , further comprising heating the initial zeolite mixture to a temperature of from 30° C. to 99° C. prior to adding the ammonium hexafluorosilicate and ammonium hydroxide to the initial zeolite mixture.
19 . The method of claim 1 , wherein the concentration of cetyltrimethylammonium bromide in the initial zeolite mixture is from 0.01 M to 1.0 M.
20 . The method of claim 1 , wherein the combining of the initial zeolite with the cetyltrimethylammonium bromide and the adding of the ammonium hexafluorosilicate and the ammonium hydroxide to the initial zeolite mixture occurs in a single vessel.