PSEUDO SOLID STATE CRYSTALLIZATION OF ZEOLITES AND USES THEREIN
Presented is a process for the preparation of zeolitic material through condensed gel crystallizations. The present disclosure describes methods for improved preparation of zeolites by preparing an aqueous precursor mixture; removing at least 5 wt % of the total water from the aqueous precursor solution to create a solution with greater solids content; crystallizing the solution of step (b) to create a zeolite product. The resulting zeolites can show improved mesoporosity without any post-treatment to create mesoporosity. This effect is particularly prominent in ZSM-5 zeolites, for example.
1 . Process for the preparation of a zeolite material by:
a. preparing an aqueous precursor mixture;
b. removing at least 5 wt % of the total water from the aqueous precursor solution to create a solution with greater solids content;
c. crystallizing the solution of step (b) to create a zeolite product.
2 . The process of claim 1 for the preparation of zeolite material with an aluminosilicate composition comprising:
a. preparing an aqueous precursor mixture from water, a silicon source, an aluminum source;
b. removing at least 5 wt % of the total water from the aqueous precursor solution to create a solution with greater solids content;
c. crystallizing the solution of step (b) to create an aluminosilicate composition.
3 . The process of claim 1 wherein there the solution of step (b) is aged for a period of time prior to the crystallizing of step (c).
4 . The process of claim 1 wherein at least 10 wt % of the total water is removed from the aqueous precursor.
5 . The process of claim 1 wherein at least 25 wt % of the total water is removed from the aqueous precursor.
6 . The process of claim 1 wherein at least 50 wt % of the total water is removed from the aqueous precursor.
7 . The process of claim 1 wherein at least 75 wt % of the total water is removed from the aqueous precursor.
8 . The process of claim 1 wherein at least 90 wt % of the total water is removed from the aqueous precursor.
9 . The process of claim 1 comprising a further step of rehydrating the product of step (b) to create a solution with greater than about 15 wt % solids prior to step (c).
10 . The process of claim 1 wherein step (c) comprises reacting the solution of step (b) at 60-300° C. for 1 minute to 48 hours and allowed to crystallize.
11 . The process of claim 1 wherein the water is removed by filtration, spraydrying or thermal treatment.
12 . The process of claim 4 wherein the water is removed by thermal treatment at a time and temperature to create a xerogel with a solids content of greater than 35 wt % solids.
13 . The process of claim 4 wherein the water is removed by spraydrying to create a flowable powder with greater than 40 wt % solids.
14 . The process of claim 13 wherein the spraydrying results in a composition of at least 75 wt % solids.
15 . The process of claim 14 wherein the spraydrying results in a composition of at least 80 wt % solids.
16 . The process of claim 4 wherein the water is removed by filtration to create a filtered gel of greater than about 25 wt % solids.
17 . The process of claim 16 wherein the filtered gel is further thermally treated to create a dry filtered powder of at least 35 wt % solids.
18 . The process of claim 9 wherein the rehydrated solution is aged for a period of time prior to the crystallizing of step (c).
19 . The process of claim 1 wherein the crystallization step (c) is thermally treated at one or more temperatures.