Ceramic wash-coat for catalyst support
View Patent ↗A wash-coat ( 16 ) for use as a support for an active catalyst species ( 18 ) and a catalytic combustor component ( 10 ) incorporating such wash-coat. The wash-coat is a solid solution of alumina or alumina-based material (Al 2 O 3 -0-3 wt % La 2 O 3 ) and a further oxide exhibiting a coefficient of thermal expansion that is lower than that exhibited by alumina. The further oxide may be silicon dioxide (2-30 wt % SiO 2 ), zirconia silicate (2-30 wt % ZrSiO 4 ), neodymium oxide (0-4 wt %), titania (Al 2 O 3 -3-40% TiO 2 ) or alumina-based magnesium aluminate spinel (Al 2 O 3 -25 wt % MgO) in various embodiments. The active catalyst species may be palladium and a second metal in a concentration of 10-50% of the concentration of the palladium.
1. A wash-coat for use as a support for an active catalyst species, the wash-coat comprising one of alumina and an alumina-based material, plus La 2 O 3 , the La 2 O 3 comprising no more than 0.3 wt %, and a further oxide other than La 2 O 3 , BaO, CeO 2 and NiO, the further oxide exhibiting a coefficient of thermal expansion that is lower than that exhibited by alumina, wherein the further oxide comprises zirconia silicate.
2. The wash-coat of claim 1 comprising 2-30 wt % ZrSiO 4 .
3. A wash-coat for use as support for an active catalyst species, the wash-coat comprising one of alumina and an alumina-based material, plus La 2 O 3 , the La 2 O 3 comprising no more than 0.3 wt %, and a further oxide other than La 2 O 3 , BaO, CeO 2 and NiO, the further oxide exhibiting a coefficient of thermal expansion that is lower than that exhibited by alumina, wherein the further oxide comprises neodymium oxide.
4. The wash-coat of claim 3 comprising no more than 4 wt % Nd 2 O 3 .
5. A wash-coat for use as a support for an active catalyst species, the wash-coat comprising one of alumina and an alumina-based material, plus La 2 O 3 , the La 2 O 3 comprising no more than 0.3 wt %, and a further oxide other than La 2 O 3 , BaO, CeO 2 and NiO, the further oxide exhibiting a coefficient of thermal expansion that is lower than that exhibited by alumina, wherein the further oxide comprises titanium oxide.
6. The wash-coat of claim 5 comprising Al 2 O 3 -3-40 wt % TiO 2 .
7. A wash-coat for use as a support for an active catalyst species, the wash-coat comprising one of alumina and an alumina-based material, plus La 2 O 3 , the La 2 O 3 comprising no more than 0.3 wt %, and a further oxide other than La 2 O 3 , BaO, CeO 2 and NiO, the further oxide exhibiting a coefficient of thermal expansion that is lower than that exhibited by alumina, further comprising alumina-based magnesium aluminate spinel in a stoichiometric concentration of Al 2 O 3 -25 wt % MgO.
8. A component for a catalytic combustor comprising:
a metallic substrate;
a ceramic catalyst support disposed on the metallic substrate; and
an active catalytic species disbursed within the ceramic catalyst support;
wherein the ceramic catalyst support comprises one of alumina and an alumina-based material plus 0-3 wt % La 2 O 3 , and a further oxide other than La 2 O 3 , BaO, CeO 2 and NiO, the further oxide exhibiting a coefficient of thermal expansion that is lower than that exhibited by alumina;
wherein a concentration of the active catalytic species varies across a depth of the ceramic catalyst support;
wherein the further oxide comprises zirconia silicate.
9. The component of claim 8 , wherein the active catalyst species further comprises palladium at a first concentration and a second metal at a second concentration of 10-50% of the first concentration.
10. The component of claim 8 , wherein the active catalyst species further comprises palladium and at least one of the group of platinum, rhodium, ruthenium, gold, nickel and rhenium.
11. The component of claim 8 , wherein the ceramic catalyst support comprises alumina-based magnesium aluminate spinel in a stoichiometric concentration of Al 2 O 3 -25 wt % MgO.
12. The component of claim 11 , wherein the active catalyst species further comprises palladium at a first concentration and a second metal at a second concentration of 10-50% of the first concentration.