Premium
Contribution of HRTEM to the characterization of silica‐incorporated copper‐oxide catalysts prepared by the Sol‐Gel technique
Author(s) -
Benaïssa M.,
Diaz G.
Publication year - 1998
Publication title -
microscopy research and technique
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 118
eISSN - 1097-0029
pISSN - 1059-910X
DOI - 10.1002/(sici)1097-0029(19980101)40:1<49::aid-jemt7>3.0.co;2-s
Subject(s) - high resolution transmission electron microscopy , copper , characterization (materials science) , catalysis , copper oxide , oxide , sol gel , materials science , chemical engineering , chemistry , nanotechnology , inorganic chemistry , nuclear chemistry , metallurgy , transmission electron microscopy , organic chemistry , engineering
The aim of the present work is a structural characterization study of silica‐incorporated copper‐oxide (CuO‐SiO 2 ) catalysts using HRTEM. The catalysts were prepared by the sol‐gel synthetic route. Two calcined catalysts (at 400°C and 800°C, respectively) were analyzed before and after the “NO x + H 2 ” catalytic reaction. It was found that in the 400°C calcined catalyst, the copper is present as CuO crystallites in a structureless form, while in the 800°C calcined catalyst, it was assumed that the copper is atomically dispersed into the silica matrix since no traces of crystalline copper were observed. Under a reducing atmosphere, i.e., after reaction, the former showed large crystallites of CuO, while in the latter a segregation of colloidal crystallites, a mixture of Cu 2 O and metallic Cu, was observed. It is worth noting that in the case of the 400°C “after‐reaction” catalyst, a change in color was observed after a few minutes of air exposure. This result suggested that the reduced copper‐oxide phase obtained after reduction was unstable. Microsc. Res. Tech. 40:49–55, 1998. © 1998 Wiley‐Liss, Inc.