Evaluation of hectorites, synthesized in different conditions, as soot combustion catalysts after impregnation with copper

Abstract

Two microporous hectorites were prepared by conventional and microwave heating, and a delaminated mesoporous hectorite by an ultrasound-assisted synthesis, and these three hectorites were impregnated with copper. The characterization techniques used were XRD, N 2 adsorption, TEM and H 2 reduction after selective surface copper oxidation by N 2 O (to determine copper dispersion). The catalytic activity for soot combustion of both the copper-free and the copper-containing hectorites was tested under a gas mixture of 500 ppm NOx/5%O 2 /N 2 (and 5% O 2 /N 2 in particular cases), evaluating their stability through three consecutive soot combustion experiments. The delaminated hectorite achieved the highest surface area (353 m 2 /g) and also the highest dispersion of copper, and this copper-containing catalyst was the most active for soot combustion among those prepared and tested in this study. It has been also concluded that the Cu/hectorite-catalyzed soot combustion mechanism is based on the activation of the O 2 molecule and not on the NO 2-assisted soot combustion.

Nanocomposite films and coatings using inorganic nanobuilding blocks (NBB): current applications and future opportunities in the food packaging sector

“…Hectorite (HEC) (Fig. 2e 220 Sinha Ray and Okamoto reported a CEC of $120 meq per 100 g. 17 A more recent study reported a CEC of 43.9 meq per 100 g, a surface area of $65 m 2 g À1 and basal spacing of 14.4 Å for Ca 2+ -HEC. 66 Other research conrmed a surface area of 63 m 2 g À1 .…”

Potential of Cu–saponite catalysts for soot combustion

“…Microwaves have also improved the occupation of Al in the tetrahedral positions and delamination. In a previous study, 19 Cu/hectorite catalysts were prepared and tested for soot combustion, and in spite of their activity, their performance was still far away from being competitive for a practical use. 3 Delaminated mesoporous hectorites have been prepared by in situ hydrothermal aging of a polyvinylpyrrolidone-containing gel 4 or quaternary ammonium salt 5,6 followed by removal of the template by calcination.…”

Research progress on the catalytic elimination of atmospheric molecular contaminants over supported metal-oxide catalysts

“…Furthermore, a lot of investigation results have shown that interactions between each component of the supported metal-oxide catalyst can be adjusted by many factors, which results in different catalytic performances. [30][31][32][33][34][35][36] These influencing factors mainly include:…”