Elsevier

Journal of Catalysis

Volume 114, Issue 1, November 1988, Pages 8-16
Journal of Catalysis

Selective synthesis of dimethylamine over small-pore zeolites: II. Effects of impurities on catalytic properties of H-RHO

https://doi.org/10.1016/0021-9517(88)90003-6Get rights and content

Abstract

Typical RHO preparations can contain impurities such as unreacted gel, chabazite, Pc, and pollucite. These impurities were synthesized in pure form to investigate their effects on the behavior of RHO as a dimethylamine (DMA)-selective catalyst in the methanol-ammonia reaction. Gel and pc, after exchange and calcination, were amorphous and inactive at typical reaction temperatures of 300–325 °C. Chabazite, always present in RHO preparations at 5–10% levels, is active and DMA selective after deep-bed calcination. After shallow-bed calcination, it loses much of its crystallinity and becomes inactive. Pollucite, appearing in the later stages of RHO crystallization, loses activity at 325 °C after shallow-bed calcination. However, after deep-bed calcination, it is an active and nonselective methylamine catalyst. Thus, the presence of pollucite can be a primary cause of lower DMA selectivity of deep-bed calcined RHO catalysts. Steaming, one of the most effective methods of reducing the activities of impurities, destroys pollucite crystallinity and/or nonselective Surface sites.

References (21)

  • R.D. Shannon et al.

    Zeolites

    (1987)
  • I. Mochida et al.

    J. Catal.

    (1983)
  • M. Keane et al.

    Appl. Catal.

    (1987)
  • Gier, T. E., Shannon, R. D., and Sonnichsen, G. C., U.S. Patent 4,602,112, July 22,...
  • Abrams, L., Gier, T. E., Shannon, R. D., and Sonnichsen, G. C., European Patent Appl. 183,...
  • R.D. Shannon et al.

    J. Catalysis

    (1988)
  • R.M. Barrer et al.

    J. Chem. Soc.

    (1959)
  • R.M. Barrer et al.

    J. Chem. Soc.

    (1959)
  • A.M. Taylor et al.

    Amer. Min.

    (1964)
  • W.M. Meier et al.
There are more references available in the full text version of this article.

Cited by (31)

  • Methanol amination over small-pore zeolite catalysts

    1997, Studies in Surface Science and Catalysis
View all citing articles on Scopus
1

Contribution 4471.

View full text