Increasing the Productivity of Colloidal Zeolite Beta by Posthydrolysis Evaporation

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Title:	Increasing the Productivity of Colloidal Zeolite Beta by Posthydrolysis Evaporation
Authors:	Fang,SY;Chiang,AST;Kao,HM
Contributors:	化學工程與材料工程學系
Keywords:	THIN-FILMS;NANOPARTICLES;NANOCRYSTALS;CRYSTALS;HEXANE;CRYSTALLIZATION;MECHANISM;CATALYSTS;BEA
Date:	2010
Issue Date:	2012-03-27 16:25:18 (UTC+8)
Publisher:	國立中央大學
Abstract:	Colloidal beta zeolite is typically synthesized by the reaction of a clear precursor sol at temperatures below 100 degrees C. The process usually suffers from limited batch productivity with a long reaction time, because of the large amount of water used in the precursor sot. Reducing the water content is expected to shorten the reaction time, enhance the productivity, and reduce the particle size, but proper procedures are required to achieve a supersaturated, but pourable, composition. A precursor sol having a record low H(2)O/SiO(2) ratio has been prepared by the addition of a posthydrolysis evaporation step. Compared to a conventional composition, which took 14 days to produce >100-nm particles at <16% yield, the supersaturated precursor achieved >60% yield of similar to 55-nm redispersible zeolite beta particles in only 6 days. The formation of beta zeolite and the evolution of it particle size during the 90 degrees C reaction confirmed that aggregation always occurred before colloidal zeolite particles could be extracted. On the other hand, the "amorphous" residue was also found to be microporous, suggesting that it might be smaller zeolite particles that were undetectable by XRD and did not settle even with the high-speed centrifugation employed.
Relation:	INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
Appears in Collections:	[Department of Chemical and Materials Engineering] journal & Dissertation

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