Zeolites with uniform intracrystal textural pores
View Patent ↗Zeolites with uniform intracrystal textural pores between 1 and 10 nm are described. Intracrystal pores, an alumina source and a silica source are reacted in the presence of a silane modified polymer as a porogen and the reaction product is calcined to form the zeolite. The zeolites are useful in catalytic reactions and adsorption processes.
1. A process for forming a calcined zeolite with uniform intracrystal textural pores, which comprises:
(a) reacting a porogen comprising a silane modified polymer, wherein the silane modified polymer comprises a polymer covalently linked to a silane modifier and the mass of the polymer per mole of the silane modifier is at least 100 grams per mole, in a mixture of an alumina source and a silica source to form a porogen-linked aluminosilicate reaction mixture;
(b) digesting the reaction mixture to form zeolite crystals with the silane modified polymer porogen occluded within the crystals; and
(c) removing the occluded intracrystal porogen from the zeolite crystals by calcination to form the calcined zeolite with the uniform intracrystal textural pores.
2. The process of claim 1 wherein the zeolite containing the occluded intracrystal porogen is calcined at a temperature between about 500° and 850° C.
3. The process of claim 1 wherein the porogen is a reaction product of (i) an amine-substituted polymer with at least one NH group and (ii) an aliphatic epoxy silane.
4. The process of any one of claim 1 , 2 or 3 wherein the silane modifier is 3-glycidoxypropyl-trimethoxysilane.
5. The process of any one of claim 1 , 2 , or 3 wherein the polymer is selected from the group consisting of a polyethyenimine and an alpha, omega-polypropylene oxide diamine.
6. The process of claim 1 wherein the uniform intracrystal textural pores of the calcined zeolite are about 1 nm to 10 nm in at least one dimension.
7. The process of claim 6 wherein: (i) the uniform intracrystal textural pores have an average pore size value centered between 1 nm and 10 nm and (i) the uniform intracrystal textural pores have a pore size distribution centered around the average pore size value being between 1 nm and 10 nm.
8. The process of claim 6 or 7 wherein the uniform intracrystal textural pores provide a pore volume of at least 0.05 cc per gram of the calcined zeolite.
9. The process of claim 6 wherein the uniform intracrystal textural pores of the calcined zeolite range in size from 1.2 nm to 2 nm.
10. The process of claim 6 wherein the uniform intracrystal textural pores of the calcined zeolite range in size from 2 nm to 10 nm.
11. The process of claim 6 wherein the uniform intracrystal textural pores of the calcined zeolite have an average pore size of less than about 7 nm.
12. The process of claim 6 wherein the uniform intracrystal textural pores of the calcined zeolite have an average pore size of less than about 5 nm.
13. The process of claim 6 wherein the mass of polymer per mole of silane modifier ranges from 100 grams per mole to 2200 grams per mole.
14. The process of claim 1 wherein the silane modified polymer comprises C—N bonds between the silane modifier and the polymer.
15. The process of claim 1 wherein, prior to reacting the porogen in the mixture of the alumina source and the silica source, the process further comprises:
(i) reacting an amine-substituted polymer containing at least one NH group with an aliphatic epoxy silane in the presence of an organic solvent to form a reaction product; and
(ii) separating the organic solvent from the reaction product to form the silane modified polymer.