Microwave-assisted zeolite synthesis from coal fly ash in hydrothermal process

Miki Inada, Hidenobu Tsujimoto, Yukari Eguchi, Naoya Enomoto, Junichi Hojo

Research output: Contribution to journalArticlepeer-review

199 Citations (Scopus)


Coal fly ashes, which include much amount of silica and alumina, can be converted into zeolite by hydrothermal alkaline treatment. In the present work, the effect of microwave irradiation on the zeolite formation was investigated with emphasis on the change in yield of zeolite during the reaction. The fly ash was mixed with 2 M NaOH solution and heated by oil bath or microwave for 2 h. Zeolite Na-P1 formed after the conventional treatment using oil bath, but no zeolitic product was obtained by microwave heating. When microwave was applied in the course of hydrothermal treatment, zeolitization was promoted by the early-stage irradiation. This is due to the stimulated dissolution of SiO 2 and Al2O3 from coal fly ash. On the other hand, the microwave irradiation in the middle to later stage retarded the crystallization of zeolite. The microwave is effective to produce the zeolite from coal fly ash in a short period by control of irradiation schedule in the early stage.

Original languageEnglish
Pages (from-to)1482-1486
Number of pages5
Issue number12-13
Publication statusPublished - Sept 2005

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Organic Chemistry


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