Compositions and processes for synthesizing cubic mesoporous silicas having “noodle-like” morphology

Patent metadata

Field	Value
Publication number	US-9452416-B2
Application number	US-201314431084-A
Country	US
Kind code	B2
Filing date	Sep 23, 2013
Priority date	Oct 1, 2012
Publication date	Sep 27, 2016
Grant date	Sep 27, 2016

Abstract

Cubic mesoporous silicas having substantially cylindrical morphology may be prepared using a combination of a first structure-directing template, such as tetramethyl ammonium hydroxide; water; a second structure-directing template, such as cetyltrimethylammonium bromide; a morphology-directing template, such as a poloxamer having a weight average molecular weight ranging from 5,000 to 20,000 Daltons; and a silica source; in the substantial absence of an alcohol solvent. The resulting materials may exhibit a three-dimensional channel structure, a length from 3 to 10 micrometers and a width from 300 nanometers to 10 micrometers, resulting in an aspect ratio from 1 to 300. Further characterization may include a surface area from 1300 to 1500 square meters per gram, an average pore diameter from 20 to 26 angstroms, and an average pore volume ranging from 0.7 to 1.1 cubic centimeters per gram. These materials are useful for molecular transport and release applications in a variety of uses, including, for example, membrane separations, metal incorporation, electronic devices, drug delivery, and adsorption.

First claim

What is claimed is:

1. A composition comprising a mesoporous silica having a three-dimensional channel structure of MCM-48 framework type, as defined by the International Zeolite Association, and having as further properties a length ranging from 3 micrometers to 10 micrometers and a width ranging from 300 nanometers to 10 micrometers, provided that the ratio of length to width characterizes an aspect ratio ranging from 1 to 300 and the morphology is substantially cylindrical; and further having a Brunauer-Emmett-Teller surface area from 1300 square meters per gram to 1500 square meters per gram, an average pore diameter from 20 angstroms to 26 angstroms, and an average pore volume ranging from 0.7 cubic centimeters per gram to 1.1 cubic centimeters per gram.

2. The composition of claim 1 wherein the mesoporous silica is characterized by at least one property selected from the group consisting of a length from 4 micrometers to 10 micrometers, a width from 500 nm to 10 micrometers, an aspect ratio from 5 to 300, a Brunauer-Emmett-Teller surface area from 1350 square meters per gram to 1450 square meters per gram, an average pore diameter from 22 angstroms to 25 angstroms, an average pore volume from 0.75 cubic centimeters per gram to 0.9 cubic centimeters per gram, and combinations thereof.

3. The composition of claim 1 wherein the mesoporous silica further exhibits a curled morphology.

4. A process for preparing a mesoporous silica comprising contacting as starting components
(1) a first structure-directing template selected from the group consisting of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and combinations thereof;
(2) water;
(3) a second structure-directing template selected from the group consisting of cetyltrimethylammonium bromide cetyltrimethylammonium bromide, hexadecyltrimethylammonium chloride; hexadecyl trimethyl ammonium hydroxide hydrate, hexadecyltrimethylammonium p-toluenesulfonate, hexadecyltrimethyl-ammonium bis-sulfonate, and combinations thereof;
(4) a morphology-directing template selected from the group consisting of poloxamers having a weight average molecular weight ranging from 5,000 Daltons to 20,000 Daltons; and
(5) a silica source;
in the substantial absence of an alcohol solvent;
under conditions such that a mesoporous silica having a three-dimensional channel structure and a substantially cylindrical morphology is formed.

5. The process of claim 4 , wherein
the first structure-directing template is tetramethylammonium hydroxide;
the second structure-directing template is cetyltrimethylammonium bromide; and
the morphology-directing template is a combination of components
(a) a non-ionic triblock copolymer based on poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol), having a molecular weight of 5,800 Daltons, and
(b) a hydrophilic nonionic, surfactant polyol having a central hydrophobic block and a molecular weight of 12,500 Daltons.

6. The process of claim 5 wherein the (a) and (b) components are in a molar ratio of (a):(b) ranging from 1.6:1 to 2500:1.

7. The process of claim 4 , wherein, based upon one mole of the silica, the amount of the first structure-directing template ranges from 0.1 mole to 0.5 mole; the amount of the water ranges from 20 moles to 80 moles; the amount of the second structure-directing template ranges from 0.25 mole to 0.5 mole; and the amount of the morphology-directing template ranges from 0.0001 mole to 0.7 mole.

8. The process of claim 4 , wherein the starting components are combined in order (1) to (5), with (1) being first and (5) last, and further wherein the starting components are stirred at a rate ranging from 300 revolutions per minute to 700 revolutions per minute while the mesoporous silica is forming.

9. The process of claim 4 wherein the conditions are selected from the group consisting of a temperature ranging from 25° C. to 190° C.; a time ranging from 5 hours to 100 hours; a pressure ranging from 101 kilopascals to 1000 kilopascals; and combinations thereof.

Assignees

• Dow Global Technologies Llc

Inventors

• Akolekar Deepak
• Bollapragada Phani Kiran

Classifications

• C01B33/12

  Silica; Hydrates thereof, e.g. lepidoic silicic acid · CPC title

• C01B37/02 Primary

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

• B01J37/0018

  Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat) · CPC title

• B01J21/08 Primary

  Silica · CPC title

• C01B33/126

  Preparation of silica of undetermined type · CPC title