Synthesis of ZSM-48 crystals with heterostructural, non ZSM-48, seeding

• US 6,923,949 B1
• Filed: 03/05/2004
• Issued: 08/02/2005
• Est. Priority Date: 03/05/2004
• Status: Expired due to Term

• Current Assignee: ExxonMobil Research & Engineering Company (Exxon Mobil Corporation)
• Original Assignee: ExxonMobil Research & Engineering Company (Exxon Mobil Corporation)
• Inventors: Verduijn, Johannes P., Mertens, Machteld M., Saunders, Richard B., Lai, Wenyih F.
• Primary Examiner(s): SAMPLE, DAVID R
• Application Number:
  US10/795,108
• Time in Patent Office: 515 Days
• Field of Search: 423/709, 423/716, 423/708, 423/705
• US Class Current: 423/709
• CPC Class Codes: C01B 39/48 using at least one organic template directing agent

Abstract

Pure phase, high activity ZSM-48 crystals having a SiO₂/Al₂O₃ ratio of less than about 150/1, substantially free from ZSM-50 and Kenyaite, and fibrous morphology crystals. The crystals may further have a specific cross morphology. A method for making such crystals using heterostructural, zeolite seeds, other than ZSM-48 and ZSM-50 seeds.

Claims

1. Pure phase ZSM-48 crystals having a XO₂/Y₂O₃ ratio of less than about 150/1 and free from ZSM-50 and Kenyaite impurities having a diameter of less than about 1 micron and being substantially free of fibrous morphology.

2. The pure phase ZSM-48 crystals of claim 1 having a XO₂/Y₂O₃ ratio of from about 40/1 to about 150/1.

3. The pure phase ZSM-48 crystals of claim 1 wherein X is at least one of Si and Ge and Y is at least on of Al, Ga, B, Fe, Ti, V and Zr.

4. The pure phase ZSM-48 of claim 1 wherein X is Si and Y is Al.

5. A method for making ZSM-48 crystals, the method comprising:

mixing effective amounts of heterostructural, zeolite seeds, selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, colloidal BEA, Beta, X and Y zeolites, at least one source of a tetravalent element X, at least one source of a trivalent element Y, an alkali or alkaline earth metal M, and at least one organic template material R;

to form a reaction mixture having in terms of mole ratios of oxides the following composition;

and maintaining said reaction mixture under effective crystallization conditions for a time sufficient to form ZSM-48 crystals.

6. The method of claim 5 wherein the organic template is selected from organic linear diquaternary alkyl ammonium compounds and linear diamino alkanes.

7. The method of claim 6 wherein the effective amount of non ZSM-48 seeds is in the range of 0.01 wt ppm to about 5 wt % based on the total weight reaction mixture.

8. The method of claim 7 wherein said heterostructural, zeolite seeds are selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, Beta, X and Y zeolites, and mixtures thereof.

9. The method of claim 5 wherein the non ZSM-48 seeds are colloidal BEA seeds in an amount in the range of about 0.01 wt ppm to about 0.1 wt % whereby the ZSM-48 crystals have a cross morphology and crystal size of about 1 to 15 μ

m.

10. A method for preparing a pure phase ZSM-48, the method comprising:

(a) preparing a reaction mixture comprising a source of silica, a source of alumina, an alkali metal or alkaline earth metal (M), water, an organic template (R), and heterostructural zeolite seeds other than ZSM-48 and ZSM-50 seeds,

wherein said mixture, in terms of mole ratios of oxides, has the following composition;

SiO₂/Al₂O₃;

30/1 to 500/1,

M⁺/SiO₂;

0.02/1 to 0.8/1,

OH⁻

/SiO₂;

0.02/1 to 0.5/1,

H₂O/SiO₂;

10/1 to 100/1, and

R/SiO₂;

0.005/1 to 1.0/1

wherein M⁺ is an alkali metal; and

R is the source of the organic structuring agents

(b) maintaining said mixture under effective crystallization conditions until crystals of said ZSM-48 are formed.

11. The method according to claim 10, wherein said mixture has the following composition ranges:

SiO₂/Al₂O₃;

40/1 to 200/1,

M⁺/SiO₂;

0.1/1 to 0.6/1,

OH⁻

/SiO₂;

0.1/1 to 0.5/1,

H₂O/SiO₂;

15/1 to 60/1, and

R/SiO₂;

0.01/1–

0.5/1.

12. The method according to claim 10, wherein the organic structuring agent is linear diquaternary ammonium compound.