NO.sub.x reduction catalyst
AssigneeNorthwestern University
InventorsWolfgang M. H. Sachtler, Haiying Chen
Life of this patent
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Abstract
A volatile metal halide is sublimed over a zeolite, which is then exposed to water, dried and calcined. A promoter may then be incorporated into the zeolite structure by adding the zeolite to a solution of a rare earth salt resulting in a metal exchanged zeolite such as La-Fe/ZSM-5. Contacting exhaust gas with NO.sub.x over the catalyst results in reduction of the NO.sub.x to N.sub.2. The spent catalyst may be regenerated by heating in an oxygen atmosphere.
Claims23
A process for the preparation of a catalyst for the removal of NO.sub.x gases from a gas stream, comprising the steps of:
- flowing a metal halide in gas form across a zeolite compound whereby the metal halide reacts with the zeolite;
- exposing the reacted zeolite to water;
- and
- heating the water exposed, reacted zeolite, thereby resulting in a catalyst for the removal of NO.sub.x gases.
A zeolite catalyst of the structure
- (M.sup.1.sub.x M.sup.2.sub.y Na.sub.a)O.sub.b (Al.sub.2 O.sub.3).sub.c (SiO.sub.2).sub.d
- where
- M.sup.1 is Fe, Ga, In, Sn or Pd;
- 0.1.ltoreq.x/c.ltoreq.5;
- M.sup.2 is La, Ce, Gd, Nd, Sm, Ho, Yb, La, Th, U, or not present;
- M.sup.1 +M.sup.2 /Al is at least about 0.8;
- 0.ltoreq.y/x.ltoreq.1.5;
- 0.ltoreq.a/c.ltoreq.2;
- 10.ltoreq.d/c.ltoreq.100;
- b=(V.sub.M.sup.1 x+V.sub.M.sup.2 y+a)/2
- (V.sub.M.sup.1 and V.sub.M.sup.2 are valences of M.sup.1 and M.sup.2, respectively).
A process for the preparation of a zeolite catalyst for the catalytic removal of NO.sub.x from a gas stream, comprising the steps of:
- a) subliming a metal halide across a zeolite compound, thereby forming a reacted zeolite;
- b) exposing the reacted zeolite to water;
- c) calcining the water exposed and reacted zeolite.
A process for the preparation of a catalyst for the removal of NO.sub.x gases from a gas stream, comprising the steps of:
- flowing a metal halide in gas form across a zeolite compound whereby the metal halide reacts with the zeolite;
- exposing the reacted zeolite to water;
- and
- heating the water exposed, reacted zeolite, thereby resulting in a catalyst for the removal of NO.sub.x gases;
- a zeolite catalyst of the structure
- (M.sup.1.sub.x M.sup.2.sub.y Na.sub.a)O.sub.b (Al.sub.2 O.sub.3).sub.c (SiO.sub.2).sub.d
- where
- M.sup.1 is Fe, Ga, In, Sn or Pd;
- 0.1.ltoreq.x/c.ltoreq.5;
- M.sup.2 is La, Ce, Gd, Nd, Sm, Ho, Yb, La, Th, U, or not present;
- .ltoreq. y/x.ltoreq.1.5;
- 0.ltoreq.a/c.ltoreq.2;
- 10.ltoreq.d/c.ltoreq.100;
- b=(V.sub.M.sup.1 X+V.sub.M.sup.2 y+a)/2
- (V.sub.M.sup.1 and V.sub.M.sup.2 are valences of M.sup.1 and M.sup.2, respectively).
A zeolite catalyst of the structure
- (M.sub.x Na.sub.a)O.sub.b (Al.sub.2 O.sub.3).sub.c (SiO.sub.2).sub.d
- where
- M is Fe, Ga, In, Sn or Pd;
- 0.8.ltoreq.M/Al.ltoreq.1.0;
- M/Al.gtoreq.0.8;
- 0.ltoreq.a/c.ltoreq.2;
- b=(V.sub.M.sup.1 x+V.sub.M.sup.2 y+a)/2
- (V.sub.M.sup.1 and V.sub.M.sup.2 are valences of M.sup.1 and M.sup.2, respectively) and
- 10.ltoreq.d/c.ltoreq.100.
Dependencies are inferred from the claim text.