Y-zeolite-containing composite material and a process for preparing the same

The invention claimed is:

1. A Y-zeolite-containing composite material, comprising a nest structure, said composite material comprising 30–85% Y-zeolite by weight and being matrix formed after crystallization of kaolin, and the crystal size of said Y-zeolite is in a range of 10–400 nm, and an equivalent diameter of said nest structure is in a range of 1000–3000 nm. 

2. The composite material according to claim 1, wherein said composite material is made from materials comprising the kaolin by in-situ crystallization. 

3. The composite material according to claim 2, wherein said materials comprising the kaolin is selected from hard kaolin or soft kaolin. 

4. The composite material according to claim 3, wherein the content of Y-zeolite is in the range of 30–70% by weight of the composite material.

5. The composite material according to claim 1, wherein said nest structure is comprised of at least 70% of rod crystal, wherein said rod crystal has a diameter of 50–200 nm and a length of 100–600 nm. 

6. The composite material according to claim 5, wherein the nest structure further comprises flaky crystal or blocky crystal, wherein the blocky crystal has an equivalent diameter of about 50–500 nm and the flaky crystal has a thickness of about 50–200 nm. 

7. The composite material according to claim 5, wherein said rod crystal, flaky crystal and blocky crystal are comprised of matrix formed after in-situ crystallization of the materials comprising kaolin and Y-zeolite on a surface of said matrix. 

8. The composite material according to claim 1, wherein an apparent bulk density of the composite material is 0.50–0.75 cm3 and a surface area is 280–800 m2/g. 

9. The composite material according to claim 1, wherein a volume of 17–3000 Å mesopore measured by BET method is 0.03–0.076 ml/g, accounting for 10–35% of a total volume of the pore. 

10. The composite material according to claim 1, wherein an SiO2/Al2O3 ratio in Y-zeolite is 4.0–5.5 by mole. 

11. The composite material according to claim 1, wherein said Y-zeolite is selected from the group consisting of NaY, HY, REY and REHY. 

12. A process for preparing the composite material according to claim 1, comprising the following steps: (1) calcining and dehydrating kaolin at 500–690° C. to convert it into metakaolin, and then into a powder with diameters less than 230 μm; (2) adding sodium silicate, guide agent, solution of sodium hydroxide, and water to metakaolin powder to make a reaction feed with a ratio of (1–2.5)Na2O: Al2O3: (4–9)SiO2: (40–100)H2O, wherein a ratio by weight of the guide agent to the metakaolin is 0.1–1.0; (3) crystallizing the reaction feed made in step (2) at 88–98° C. under stirring, and then filtering and drying. 

13. The process according to claim 12, wherein the composition of said guide agent in step (2) is (10–17)SiO2:(0.7–1.3)Al2O3:(11–18) Na2O: (200–350)H2O, and the guide agent is made by aging at 4–20° C. 

14. The process according to claim 12, wherein the temperature for calcining raw material powder in step (1) is in a range of 600–690 ° C. 

15. The process according to claim 12, wherein a stirring rate for crystallization in step (3) is 200–1000 rpm and a crystallization time is 16–48 hours. 

16. The process according to claim 12, wherein a concentration of the added solution of sodium hydroxide in step (2) is 1–10% by weight. 

17. The process according to claim 12, wherein said kaolin in step (1) is selected from hard kaolin or soft kaolin, containing more than 75% by weight of crystal. 

18. The process according to claim 12, wherein an auxiliary accounting for 0.1–2.5% by weight of the total reaction feed is further added to the feed in step (2), and the auxiliary is selected from the group consisting of sodium dodecyl sulfonate, hexadecyl trimethyl ammonium bromide, polyethylene glycol, oxalic acid, citric acid, sodium tartrate, and ethylenediamine tetraacetic acid. 

19. A process for preparing the composite material according to claim 1, comprising the following steps: (1) calcining and dehydrating kaolin at 500–690° C. to convert it into metakaolin, and then into a powder with diameters less than 230 μm; (2) adding sodium silicate, guide agent, solution of sodium hydroxide, and water to metakaolin powder to make a reaction feed with a ratio of (1–2.5)Na2O: Al2O3: (4–9)SiO2: (40–100)H2O, wherein said guide agent is made by aging at 4–20° C. and a ratio by weight of the guide agent to the metakaolin is 0.1–1.0; (3) crystallizing the reaction feed made in step (2) at 88–98° C. under stirring, and then filtering and drying.