Synthesis of ZSM-5

Patent metadata

Field	Value
Publication number	US-9757716-B2
Application number	US-201314648476-A
Country	US
Kind code	B2
Filing date	Nov 22, 2013
Priority date	Dec 21, 2012
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

A molecular sieve having the framework structure of ZSM-5 is produced using one or more of 1,4-bis(N-pentylpyrrolidinium)butane dications, 1,5-bis(N-pentylpyrrolidinium)pentane dications, and 1,6-bis(N-pentylpyrrolidinium)hexane dications as a structure directing agent.

First claim

The invention claimed is:

1. A process for producing a molecular sieve having the structure of ZSM-5, the process comprising:
(i) preparing a synthesis mixture capable of forming said molecular sieve, said synthesis mixture comprising a source of an alkali or alkaline earth metal (M), a source of an oxide of a tetravalent element Y, optionally a source of a trivalent element X, water, and a directing agent (Q) comprising one or more of 1,4-bis(N-pentylpyrrolidinium)butane dications, 1,5-bis(N-pentylpyrrolidinium)pentane dications, and 1,6-bis(N-pentylpyrrolidinium)hexane dications, and said synthesis mixture having a composition, in terms of mole ratios, within the following ranges:

YO 2 /X 2 O 3
at least 20;

H 2 O/YO 2
  10 to 60;

OH − /YO 2
0.20 to 0.60;

M/YO 2
0.05 to 0.40; and

Q/YO 2
0.05 to 0.20;

(ii) heating said synthesis mixture under crystallization conditions, including a temperature of from 80° C. to 200° C., and a time from 1 day to 21 days, until crystals of said molecular sieve are formed; and
(iii) recovering said molecular sieve from step (ii),
wherein (a) 1,4-bis(N-pentylpyrrolidinium)butane dications which can be represented by the following formula:

(b) 1,5-bis(N-pentylpyrrolidinium)pentane dications can be represented by the following formula:

and
(c) 1,6-bis(N-pentylpyrrolidinium)hexane dications can be represented by the following formula:

wherein said tetravalent element Y comprises silicon, and said trivalent element X comprises aluminum.

2. The process of claim 1 , wherein said synthesis mixture has a composition, in terms of mole ratios, within the following ranges:

YO 2 /X 2 O 3
at least 24;

H 2 O/YO 2
  20 to 50;

OH − /YO 2
0.25 to 0.50;

M/YO 2
 0.1 to 0.40; and

Q/YO 2
0.05 to 0.20.

3. The process of claim 1 , wherein said synthesis mixture also contains seeds.

4. The process of claim 3 , wherein said synthesis mixture comprises from about 0.01 ppm by weight to about 10,000 ppm by weight of seeds.

5. The process of claim 3 , wherein said synthesis mixture comprises from about 100 ppm by weight to about 5,000 ppm by weight of seeds.

6. The process of claim 3 , wherein said seeds comprise a crystalline material having the structure of ZSM-5.

7. The process of claim 1 and further comprising the step of removing at least part of said directing agent from the molecular sieve crystals recovered in step (iii).

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Burton Allen W

Classifications

• B01J35/70

  characterised by their crystalline properties, e.g. semi-crystalline (catalysts comprising carbon B01J21/18; molecular sieves B01J29/00) · CPC title

• B01J2235/30

  Scanning electron microscopy; Transmission electron microscopy · CPC title

• B01J2235/15

  X-ray diffraction · CPC title

• B01J29/00

  Catalysts comprising molecular sieves {(molecular sieves per se C01B)} · CPC title

• C01B37/02 Primary

  Crystalline silica-polymorphs, e.g. silicalites {dealuminated aluminosilicate zeolites} · CPC title