Characterization of alumina gel catalysts by emanation thermal analysis (ETA)

Hiroshi Hirashima, Hiroaki Imai, Vladimir Balek

Research output: Contribution to journalArticle

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Abstract

Alumina gels made from the metal alkoxide is known to have high catalyst activity for the selective reduction of NOx by hydrocarbons. It is also reported that the fine structure of the gels effects the activity. In this study, the effect of the preparation method on the fine structure and catalyst activity of the gels was investigated. Monolithic gels were obtained by hydrolysis of Al(sec-C4H9O)3. The wet gels were dried at 90°C (xerogels), supercritically dried (aerogels), or dried after immersion in an ethanol solution of methyltrimethoxysilane (modified xerogels). The changes in the microstructure during heating were discussed using the results of TG-DTA, ETA and N2 adsorption. The ETA curves show the 220Rn-release rate, E, of the samples, previously labelled with 228Th and 224Ra, during heating. The decrease in E of the xerogel at temperatures higher than 400°C indicates a gradual decrease in the surface area and porosity. A remarkable decrease in the BET surface area of the xerogel was found after heat-treating at 500°C. On the other hand, constant E of the aerogels and modified xerogels above 450°C suggests high thermal stability. The pore radii, estimated by BJH method, and the catalyst activities at 500°C of the aerogels and the modified xerogels were higher than those of the xerogels. The temperature range in which the alumina gels are applicable as catalysts was determined.

Original languageEnglish
Pages (from-to)399-402
Number of pages4
JournalJournal of Sol-Gel Science and Technology
Volume19
Issue number1-3
DOIs
Publication statusPublished - 2000 Dec

Fingerprint

Xerogels
xerogels
Aluminum Oxide
Thermoanalysis
thermal analysis
Alumina
Gels
aluminum oxides
gels
catalysts
Catalysts
Aerogels
aerogels
Catalyst activity
fine structure
porosity
Heating
heating
alkoxides
Hydrocarbons

ASJC Scopus subject areas

  • Ceramics and Composites

Cite this

Characterization of alumina gel catalysts by emanation thermal analysis (ETA). / Hirashima, Hiroshi; Imai, Hiroaki; Balek, Vladimir.

In: Journal of Sol-Gel Science and Technology, Vol. 19, No. 1-3, 12.2000, p. 399-402.

Research output: Contribution to journalArticle

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