A sol-gel process for synthesis of nanocrystalline oxides

Patent metadata

Field	Value
Publication number	US-2016122195-A1
Application number	US-201414889792-A
Country	US
Kind code	A1
Filing date	May 9, 2014
Priority date	May 9, 2013
Publication date	May 5, 2016
Grant date	—

Abstract

A Continuous flow synthesis of nanocrystalline metal oxides by rapid sol-gel process is disclosed. The process disclosed uses an impinging microjet micromixer device to obtain the nano crystalline metal oxides. A method of fabricating and assembling the impinging microjet micromixer is also disclosed herewith.

First claim

1 . An impinging jet micromixer comprising inlets for reactant ( 1 ) and ( 2 ) being connected to metallic blocks having microscopic bore ( 6 ), being connected to support plates ( 3 ) using support tension springs ( 4 ) and screw for adjusting angle of the impinging sections ( 5 ), wherein mixing zone ( 7 ) is formed by the impinging jets coming out of said bores ( 6 ) wherein the angle between the impinging jets is in the range of 70-120 degrees and the aspect ratio is in the range of 0.6-1.2.

2 . A sol-gel process for continuous flow synthesis of nanocrystalline metal oxides using the impinging jet micromixer as claimed in claim 1 , comprising the steps of:
i. pumping of water and metal alkoxide solution in a solvent continuously through inlets ( 1 ) and ( 2 ) followed by mixing, in a mixing zone: ii. synthesizing wet gel samples at flow rates in the range of 10 to 20 ml Jmin for the jet diameter in the range of 100-1000 micron and at angles between jets in the range of 70-140 degree to obtain a gel; iii. ageing the gel as obtained in step (ii), vacuum drying at temperature in the range of 70 to 90° C. for a period in the range of 8 to 12 hours, followed by calcination at a temperature in the range of 350-600° C.; and iv. drying the gel as obtained in step (iii) at a temperature in the range of 80-90° C. to yield nanocrystalline Metal Oxide having BET surface area in the range of 220-520 m2 /g and average crystallite size is in the range of 4.5-6.0 pm.

3 . The process according to claim 2 , wherein the solvent used is methanol and toluene such that the toluene to methanol volume ratio becomes 1.60 upon the addition of equal amounts of both the reactants.

4 . The process according to claim 2 , wherein the rate of mixing is faster than the rate of reaction to achieve homogeneous nucleation.

5 . The process according to claim 2 , wherein the metal alkoxide is selected from the group consisting of Zirconium alkoxide, Strontium alkoxide, and Magnesium alkoxide.

6 . The process according to claim 2 , wherein the nanocrystalline metal oxide is selected from the group consisting of Zirconium oxide, Strontium oxide, and magnesium oxide.

7 . The process according to claim 2 , wherein the ratio of metal alkoxide to water in step (i) is 1:2 to 1:5.

8 . The impinging jet micromixer according to claim 1 , wherein the aspect ratio is 1.

9 . The impinging jet micromixer according to claim 1 , wherein the thickness of the mixing zone in the micromixer has a thickness is in the range of 7.2 to 20.7 μm.

10 . A method of fabricating and assembling the impinging microjet micromixer comprising attaching two micro-machined segments ( 6 ) on a backbone structure of micromixer so as to allow a change in the angle between the microchannels in the same plane comprising the steps of:
a) machining the microchannels of 0.3 mm diameter in SS316 segments ( 6 ); and b) adjusting the two segments ( 6 ) simultaneously using tension springs ( 4 ) to ensure that the two segments ( 6 ) are held at a fixed distance and at a fixed angle by using the rotation screw ( 5 ), to get equal angular distance from the point of jet interaction.

Assignees

• Council Scient Ind Res

Inventors

• Darbha Venkata Ravi Kumar
• Bhagavatula Lakhsmi Vara Prasad
• Kulkarni Amol Arvind

Classifications

• B01J19/0093

  Microreactors, e.g. miniaturised or microfabricated reactors (laboratory containers with capillary fluid transport in microfabricated channels or chambers B01L3/5027) · CPC title

• B01F15/00922

  Operations & Transport · mapped topic

• B01J2219/00889

  Mixing · CPC title

• C01F5/02 Primary

  Magnesia · CPC title

• C01G25/02

  Oxides · CPC title