ISSN:
1572-879X
Keywords:
TPR
;
crystallinity
;
Ni-talc
;
chrysocolla
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Reference phyllosilicates (Ni-talcs and chrysocolla) have been synthesized with the aim of identifying supported layered silicates in the preparation of Ni/SiO2 and Cu/SiO2 materials. The analysis of temperature programmed reduction (TPR) profiles and X-ray diffraction (XRD) patterns of talc synthesized at different temperatures shows a strong influence of the crystallinity of the Ni silicate on its reducibility. Chrysocolla remains ill-crystallized whatever the temperature of synthesis. The reducibility of the two silicates is discussed in terms of the structure of the silicate and the reducibility of the transition metal-ion. The asymmetric shape of the TPR curves of Ni-talcs is interpreted on the basis of the phase-boundary controlled model and the presence of a heterogeneous particle size distribution. The results emphasize the role of the crystallinity and show that the identification of supported silicate phases from TPR only may not be reliable.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00815422
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