ISSN:
1572-879X
Keywords:
volatilization
;
steam
;
transition metal hydroxides
;
NiO
;
Co3O4
;
CuO
;
Al2O3
;
Rutherford backscattering spectrometry (RBS)
;
solid state reaction
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract To study the influence of steam on the solid state reaction between MeO (Me = Ni, Co, Cu or Fe) and Al2O3, MeO/α-Al2O3 and MeO/γ-Al2O3 model catalysts were kept in either N2/20% O2 or N2/O2/30% H2O at 500–1000°C. The samples were subsequently analyzed with RBS and FTIR. Surprisingly, nickel, cobalt and copper volatilized when MeO/α-Al2O3 or MeAl2U4/α-Al2O3 samples were annealed in the presence of 0.3 atm steam at 1000°C. Especially copper was found to volatilize very rapidly in the presence of steam, even at a temperature as low as 800°C. FTIR spectra of steam-treated NiO/α-Al2O3 samples showed the incorporation of hydroxyl groups in the nickel oxide layer. This observation and an excellent agreement with thermochemical calculations support our conclusion that the volatile species are metal hydroxides. The solid state reaction of MeO withγ-Al2O3 was found to proceed at a much higher rate in the presence of 0.3 atm steam at 500–800°C, presumably as a result of an enhanced surface mobility of Me and Al ions along the grain boundaries and the surfaces of the internal pores of theγ-Al2O3 support, when steam is present.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00805588
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