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Abstract(s)
The reuse of waste fluid catalytic cracking (FCC) catalyst as partial surrogate for cement can
reduce the environmental impact of both the oil-refinery and cement production industries
[1,2]. FCC catalysts can be considered as pozzolanic materials since in the presence of water
they tend to chemically react with calcium hydroxide to produce compounds possessing
cementitious properties [3,4]. In addition, partial replacement of cement with FCC catalysts
can enhance the performance of pastes and mortars, namely by improving their compressive
strength [5,6].
In the present work the reaction of waste FCC catalyst with Ca(OH)2 has been investigated
after a curing time of 28 days by scanning electron microscopy (SEM) with electron
backscattered signal (BSE) combined with X-ray energy dispersive spectroscopy (EDS)
carried out with a JEOL JSM 7001F instrument operated at 15 kV coupled to an INCA
pentaFetx3 Oxford spectrometer. The polished cross-sections of FCC particles embedded in
resin have also been evaluated by atomic force microscopy (AFM) in contact mode (CM)
using a NanoSurf EasyScan 2 instrument.
The SEM/EDS results revealed that an inward migration of Ca occurred during the reaction.
A weaker outward migration of Si and Al was also apparent (Fig. 1). The migration of Ca
was not homogeneous and tended to follow high-diffusivity paths within the porous waste
FCC catalyst particles. The present study suggests that the porosity of waste FCC catalysts is
key for the migration/reaction of Ca from the surrounding matrix, playing an important role
in the pozzolanic activity of the system. The topography images and surface roughness
parameters obtained by atomic force microscopy can be used to infer the local porosity in
waste FCC catalyst particles (Fig. 2).
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Citation
JEREMIAS, J.; [et al.] - Pozzolanic activity of oil-refining catalyst: evaluation by electron and atomic microscopy. Microscopy and Microanalysis. ISSN 1431-9276. Vol. 21, S6, (2015), 80-81.
Publisher
Microscopy Society of America