Rapid method for production of cerium-containing oxide organic colloids

Abstract

Improved methods for producing colloidal dispersions of cerium-containing oxide nanoparticles in substantially non-polar solvents is disclosed. The cerium-containing oxide nanoparticles of an aqueous colloid are transferred to a substantially non-polar liquid comprising one or more amphiphilic materials, one or more low-polarity solvents, and, optionally, one or more glycol ether promoter materials. The transfer is achieved by mixing the aqueous and substantially non-polar materials, forming an emulsion, followed by a phase separation into a remnant polar solution phase and a substantially non-polar organic colloid phase. The organic colloid phase is then collected. The promoter functions to speed the transfer of nanoparticles to the low-polarity phase. The promoter accelerates the phase separation, and also provides improved colloidal stability of the final substantially non-polar colloidal dispersion. The glycol ether promoter reduces the temperature necessary to achieve the phase separation, while providing high extraction yield of nanoparticles into the low-polarity organic phase. In addition, use of particular amphiphilic materials, such as heptanoic acid or octanoic acid, enable efficient extractions at ambient temperatures without the use of a glycol ether promoter.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation-in-part of U.S. patent application Ser. No. 13 / 753,992, IMPROVED METHOD FOR PRODUCTION OF STABLE CERIUM OXIDE ORGANIC COLLOIDS, filed Jan. 30, 2013, which claims priority to U.S. Provisional Application No. 61 / 632,778, filed Jan. 30, 2012, the disclosures of which are incorporated herein by reference in its entirety. This application also claims the benefit of priority to Provisional Application Ser. No. 61 / 632,881, METHOD FOR PRODUCTION OF STABLE CERIUM OXIDE ORGANIC COLLOIDS, filed Feb. 1, 2012, the disclosure of which is incorporated herein by reference in its entirety.FIELD OF THE INVENTION[0002]The present invention relates generally to colloidal nanoparticle dispersions and more specifically to improved processes for the manufacture of doped and un-doped cerium oxide colloidal dispersions in solvents having low-polarity.BACKGROUND OF THE INVENTION[0003]Cerium-containing oxide nanoparticles have man...

AI Technical Summary

Benefits of technology

The present invention provides a simple, rapid, low temperature process for producing stable cerium oxide nanoparticle dispersions in low-polarity solvents. This is achieved by using a glycol ether promoter material which accelerates the transfer of nanoparticles to the low-polarity phase and provides improved dispersion stability. The process involves mixing an aqueous dispersion of cerium oxide nanoparticles with a non-polar liquid containing amphiphilic materials and low-polarity solvents, resulting in an emulsion which then separates into a polar solution phase and a non-polar dispersion phase. The non-polar dispersion phase is then collected. This process reduces the temperature and time required for processing, resulting in lower energy costs and reduced risk of hazard.

Problems solved by technology

However, conventional aqueous processes—precipitation in particular—are costly as they involve multiple steps that are often time and energy consuming, as well as equipment intensive.

However, most particle stabilizers used to prevent particle agglomeration in an aqueous environment are ill-suited to the task of stabilization in a non-polar environment.

When placed in a non-polar solvent, such particles tend to immediately agglomerate and, consequently, lose some, if not all, of their desirable particulate properties.

Changing stabilizers can involve a difficult displacement reaction or separate, tedious isolation and re-dispersal methods such as, for example, precipitation and subsequent re-dispersal with a new stabilizer using, for instance, a ball milling process. which can take several days and tends to produce polydisperse size frequency distributions.

However, drawbacks of diafiltration methods include the following: relatively slow filtration rates, substantial financial investment in equipment (e.g. pumps and microfilters), and production of a relatively large amount (e.g. several turnover volumes) of waste solvent.

However, high process temperatures and times for the transfer of the colloidal particulates represent a significant limitation of the prior art process.

It is also apparent that concern over the presence of ionic constituents, and other materials needed to bring about the formation of the colloidal particulate material in the aqueous reaction mixture, affects the viability of the direct process.

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