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Title: Production of cerium dioxide microspheres by an internal gelation sol–gel method

Abstract

An internal gelation sol-gel technique was used to prepare cerium dioxide microspheres with uniform diameters near 100 µm. In this process, chilled aqueous solutions containing cerium, hexamethylenetetramine (HMTA), and urea are transformed into a solid gel by heat addition and are subsequently washed, dried, and sintered to produce pure cerium dioxide. Cerous nitrate and ceric ammonium nitrate solutions were compared for their usefulness in microsphere production. Gelation experiments were performed with both cerous nitrate and ceric ammonium nitrate to determine desirable concentrations of cerium, HMTA, and urea in feed solutions as well as the necessary quantity of ammonium hydroxide added to cerium solutions. Analysis of the pH before and after sample gelation was found to provide a quantitative metric for optimal parameter selection along with subjective evaluations of gel qualities. The time necessary for chilled solutions to gel upon inserting into a hot water bath was determined for samples with a variety of parameters and also used to determine desirable formulations for microsphere production. A technique for choosing the optimal mixture of ceric ammonium nitrate, HMTA, and urea was determined using gelation experiments and used to produce microspheres by dispersion of the feed solution into heated silicone oil. Gelled spheresmore » were washed to remove excess reactants and reaction products before being dried and sintered. X-ray diffraction of air-dried microspheres, sintered microspheres, and commercial CeO 2 powders indicated that air-dried and sintered spheres were pure CeO 2.« less

Authors:
ORCiD logo
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1361970
Report Number(s):
PNNL-SA-123942
Journal ID: ISSN 0928-0707
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Sol-Gel Science and Technology; Journal Volume: 82; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; 11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; sol-gel; internal gelation; cerium oxide; microsphere; nuclear fuel

Citation Formats

Katalenich, Jeffrey A. Production of cerium dioxide microspheres by an internal gelation sol–gel method. United States: N. p., 2017. Web. doi:10.1007/s10971-017-4345-8.
Katalenich, Jeffrey A. Production of cerium dioxide microspheres by an internal gelation sol–gel method. United States. doi:10.1007/s10971-017-4345-8.
Katalenich, Jeffrey A. Mon . "Production of cerium dioxide microspheres by an internal gelation sol–gel method". United States. doi:10.1007/s10971-017-4345-8.
@article{osti_1361970,
title = {Production of cerium dioxide microspheres by an internal gelation sol–gel method},
author = {Katalenich, Jeffrey A.},
abstractNote = {An internal gelation sol-gel technique was used to prepare cerium dioxide microspheres with uniform diameters near 100 µm. In this process, chilled aqueous solutions containing cerium, hexamethylenetetramine (HMTA), and urea are transformed into a solid gel by heat addition and are subsequently washed, dried, and sintered to produce pure cerium dioxide. Cerous nitrate and ceric ammonium nitrate solutions were compared for their usefulness in microsphere production. Gelation experiments were performed with both cerous nitrate and ceric ammonium nitrate to determine desirable concentrations of cerium, HMTA, and urea in feed solutions as well as the necessary quantity of ammonium hydroxide added to cerium solutions. Analysis of the pH before and after sample gelation was found to provide a quantitative metric for optimal parameter selection along with subjective evaluations of gel qualities. The time necessary for chilled solutions to gel upon inserting into a hot water bath was determined for samples with a variety of parameters and also used to determine desirable formulations for microsphere production. A technique for choosing the optimal mixture of ceric ammonium nitrate, HMTA, and urea was determined using gelation experiments and used to produce microspheres by dispersion of the feed solution into heated silicone oil. Gelled spheres were washed to remove excess reactants and reaction products before being dried and sintered. X-ray diffraction of air-dried microspheres, sintered microspheres, and commercial CeO2 powders indicated that air-dried and sintered spheres were pure CeO2.},
doi = {10.1007/s10971-017-4345-8},
journal = {Journal of Sol-Gel Science and Technology},
number = 3,
volume = 82,
place = {United States},
year = {Mon Mar 27 00:00:00 EDT 2017},
month = {Mon Mar 27 00:00:00 EDT 2017}
}