CATALYST AND PROCESS FOR THE CONVERSION OF NITROUS OXIDE
A catalyst composition and a process for using it to decompose nitrous oxide into nitrogen and oxygen are disclosed. The catalyst composition has surface area of about 1 to about 200 m 2 /g after exposure to a calcination temperature of between about 400° C. and about 900° C., or about 1 to about 100 m 2 /g after exposure to a calcination temperature of between about 400° C. and about 950° C.
1 . A catalyst composition comprising a zirconium oxide substrate which includes one or more oxides of at least one of the following: Ca, Sr, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, W, Ti, Al, Si, Ge, or Sn, as a dopant or dopants, the catalyst composition further comprising nickel oxide, cobalt oxide or a combination thereof.
2 . A catalyst composition of claim 1 , wherein the one or more oxides are oxides of La, Ce, Nd or W.
3 . A catalyst composition of claim 1 , which has surface area of about 1 to about 200 m 2 /g after exposure to a calcination temperature between about 400° C. and about 900° C.
4 . A catalyst composition of claim 1 , which has surface area of about 5 to about 100 m 2 /g after exposure to a calcination temperature between about 400° C. and about 900° C.
5 . A catalyst composition of claim 1 , wherein the zirconium oxide substrate includes from about 1 to about 10% by weight of one or more oxides of at least one of the following: Ca, Sr, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, W, Ti, Al, Si, Ge, or Sn, as a dopant or dopants.
6 . A catalyst composition of claim 1 , which has the catalyst deactivation rate constant for decomposition of N 2 O at 800° C. of less than 8×10 −4 hr −1 , and a deactivation rate constant based on surface area of less than 0.03 day −1 at 900° C.
7 . A catalyst composition of claim 1 , which has the catalyst deactivation rate constant for decomposition of N 2 O at 800° C. of less than 4×10 −4 hr −1 , and a deactivation rate constant based on surface area of less than 0.01 day −1 at 900° C.
8 . A process for converting N 2 O to nitrogen and oxygen comprising contacting the N 2 O with a catalyst composition which comprises a zirconium oxide substrate which includes one or more oxides of at least one of the following: Ca, Sr, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, W, Ti, Al, Si, Ge, or Sn, as a dopant or dopants.
9 . A process of claim 8 , wherein the catalyst composition further comprises nickel oxide, cobalt oxide or a combination thereof.
10 . A process of claim 8 , wherein the dopant or dopants are included in a solid solution in the zirconium oxide.
11 . A process of claim 9 , wherein the nickel oxide, cobalt oxide or a combination thereof are catalytically active metals deposited upon surface of the zirconium oxide substrate.
12 . A process of claim 8 , wherein the catalyst composition has surface area of about 1 to about 200 m 2 /g after exposure to a calcination temperature between about 400 and about 900° C.
13 . A process of claim 8 , wherein the catalyst composition has surface area of about 5 to about 100 m 2 /g after exposure to a temperature of about 400° C. to about 900° C.
14 . A catalyst composition of claim 8 , which has the catalyst deactivation rate constant for decomposition of N 2 O at 800° C. of less than 8×10 −4 hr −1 , and a deactivation rate constant based on surface area of less than 0.03 day −1 at 900° C.
15 . A catalyst composition of claim 8 , which has the catalyst deactivation rate constant for decomposition of N 2 O at 800° C. of less than 4×10 −4 hr −1 , and a deactivation rate constant based on surface area of less than 0.01 day −1 at 900° C.
16 . A process for converting N 2 O to nitrogen and oxygen comprising contacting the N 2 O with a catalyst composition which comprises nickel oxide, cobalt oxide or a combination thereof on a zirconia substrate, the catalyst composition having surface area of about 1 to about 200 m 2 /g after exposure to a calcination temperature of between about 400 and about 900° C.
17 . A process of claim 16 , wherein the catalyst composition has surface area of about 5 to about 100 m 2 /g after exposure to a temperature of between about 400° C. and about 900° C.
18 . A catalyst composition of claim 16 , which has the catalyst deactivation rate constant for decomposition of N 2 O at 800° C. of less than 8×10 −4 hr −1 , and a deactivation rate constant based on surface area of less than 0.03 day −1 at 900° C.
19 . A catalyst composition of claim 16 , which has the catalyst deactivation rate constant for decomposition of N 2 O at 800° C. of less than 4×10 −4 hr −1 , and a deactivation rate constant based on surface area of less than 0.01 day −1 at 900° C.
20 . A catalyst composition having surface area of about 1 to about 200 m 2 /g after exposure to a calcination temperature between about 400 and about 900° C. prepared by a method comprising:
a. providing a solution of zirconium chloride;
b. adding to the solution of zirconium chloride a source of at least one of the following:
Ca, Sr, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, W, Ti, Al, Si, Ge, or Sn;
c. adding to the product of (b) a solution of ammonium hydroxide or sodium hydroxide under conditions sufficient to produce a solution of zirconium hydroxide;
d. maintaining the solution of zirconium hydroxide at an elevated temperature for a time sufficient to produce a precipitated zirconium hydroxide;
e. substantially removing Cl − ions from the precipitated zirconium hydroxide;
f. drying the zirconium hydroxide;
g. calcining the zirconium hydroxide to produce zirconium oxide;
h. preparing an aqueous solution of zirconium oxide;
i. adding to the aqueous solution of zirconium oxide an aqueous solution of a source of nickel, an aqueous solution of a source of cobalt or a combination thereof;
j. removing liquid from the product of (i) to produce a wet catalyst composition;
k. drying the wet catalyst composition;
l. calcining the dried catalyst composition to produce the catalyst composition.
21 . A catalyst composition of claim 20 which has surface area of about 5 to about 100 m 2 /g after exposure to a calcination temperature of between about 400° C. and about 900° C.
22 . A catalyst composition of claim 20 , which has the catalyst deactivation rate constant for decomposition of N 2 O at 800° C. of less than 8×10 −4 hr −1 , and a deactivation rate constant based on surface area of less than 0.03 day −1 at 900° C.
23 . A catalyst composition of claim 20 , which has the catalyst deactivation rate constant for decomposition of N 2 O at 800° C. of less than 4×10 −4 hr −1 , and a deactivation rate constant based on surface area of less than 0.01 day −1 at 900° C.
24 . A catalyst composition having surface area of about 1 to about 200 m 2 /g after exposure to a calcination temperature of between about 400° C. and about 900° C., prepared by a method comprising:
(i) providing a solution of zirconium chloride;
(ii) adding to a solution of ammonium hydroxide or sodium hydroxide the solution of zirconium chloride under conditions sufficient to produce a solution of zirconium hydroxide;
(iii) maintaining the solution of zirconium hydroxide at an elevated temperature or at room temperature for a time sufficient to produce a precipitated zirconium hydroxide;
(iv) substantially removing ClF ions from the precipitated zirconium hydroxide;
(v) drying the zirconium hydroxide;
(vi) calcining the zirconium hydroxide to produce zirconium oxide;
(vii) preparing an aqueous solution of zirconium oxide;
(viii) adding to the aqueous solution of zirconium oxide an aqueous solution of a source of nickel, an aqueous solution of a source of cobalt or a combination thereof;
(ix) removing liquid from the product of (viii) to produce a wet catalyst composition;
(x) drying the wet catalyst composition; and
(xi) calcining the dried catalyst composition to produce the catalyst composition.
25 . A catalyst composition of claim 24 which has surface area of about 5 to about 100 m 2 /g after exposure to a calcination temperature between 400° C. and about 900° C.
26 . A catalyst composition of claim 24 , which has the catalyst deactivation rate constant for decomposition of N 2 O at 800° C. of less than 8×10 −4 hr −1 , and a deactivation rate constant based on surface area of less than 0.03 days −1 at 900° C.
27 . A catalyst composition of claim 24 , which has the catalyst deactivation rate constant for decomposition of N 2 O at 800° C. of less than 4.0×10 −4 hr −1 , and a deactivation rate constant based on surface area of less than 0.01 day −1 at 900° C.
28 . A method for making a catalyst composition comprising:
(i) providing a solution of zirconium chloride;
(ii) adding to the solution of zirconium chloride a source of at least one of the following: Ca, Sr, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, W, Ti, Al, Si, Ge, or Sn;
(iii) adding to the product of (ii) a solution of ammonium hydroxide or sodium hydroxide under conditions sufficient to produce a solution of zirconium hydroxide;
(iv) maintaining the solution of zirconium hydroxide at an elevated temperature for a time sufficient to produce a precipitated zirconium hydroxide;
(v) substantially removing Cl − ions from the precipitated zirconium hydroxide;
(vi) drying the zirconium hydroxide;
(vii) calcining the zirconium hydroxide to produce zirconium oxide;
(viii) preparing an aqueous solution of zirconium oxide;
(ix) adding to the aqueous solution of zirconium oxide an aqueous solution of a source of nickel, an aqueous solution of a source of cobalt or a combination thereof;
(x) removing liquid from the product of (ix) to produce a wet catalyst composition;
(xi) drying the wet catalyst composition;
(xii) calcining the dried catalyst composition to produce the catalyst composition.
29 . A method of claim 28 wherein the catalyst composition has surface area of about 1 to about 200 m 2 /g after exposure to a calcination temperature of between about 400° C. and about 900° C.
30 . A method of claim 28 wherein the catalyst composition has surface area of about 5 to about 100 m 2 /g after exposure to a calcination temperature of between about 400° C. and about 900° C.
31 . A catalyst composition of claim 28 , which has the catalyst deactivation rate constant for decomposition of N 2 O at 800° C. of less than 8×10 −4 hr −1 , and a deactivation rate constant based on surface area of less than 0.03 day −1 at 900° C.
32 . A catalyst composition of claim 28 , which has the catalyst deactivation rate constant for decomposition of N 2 O at 800° C. of less than 4×10 −4 hr −1 , and a deactivation rate constant based on surface area of less than 0.01 day −1 at 900° C.
33 . A method for making a catalyst composition comprising:
(i) providing a solution of zirconium chloride;
(ii) adding to a solution of ammonium hydroxide or sodium hydroxide the solution of zirconium chloride under conditions sufficient to produce a solution of zirconium hydroxide;
(iii) maintaining the solution of zirconium hydroxide at an elevated temperature or at room temperature for a time sufficient to produce a precipitated zirconium hydroxide;
(iv) substantially removing Cl − ions from the precipitated zirconium hydroxide;
(v) drying the zirconium hydroxide;
(vi) calcining the zirconium hydroxide to produce zirconium oxide;
(vii) preparing an aqueous solution of zirconium oxide;
(viii) adding to the aqueous solution of zirconium oxide an aqueous solution of a source of nickel, an aqueous solution of a source of cobalt or a combination thereof;
(ix) removing liquid from the product of (viii) to produce a wet catalyst composition;
(x) drying the wet catalyst composition; and
(xi) calcining the dried catalyst composition to produce the catalyst composition.
34 . A method of claim 33 , wherein the catalyst composition has surface area of about 1 to about 200 m 2 /g after exposure to a calcination temperature between about 400 and about 900° C.
35 . A method of claim 33 , wherein the catalyst composition has surface area of about 5 to about 100 m 2 /g after exposure to a calcination temperature of between about 400° C. and about 900° C.
36 . A method of claim 33 , which has the catalyst deactivation rate constant for decomposition of N 2 O at 800° C. of less than 8×10 −4 hr −1 , and a deactivation rate constant based on surface area of less than 0.03 days −1 at 900° C.
37 . A method of claim 33 , which has the catalyst deactivation rate constant for decomposition of N 2 O at 800° C. of less than 4×10 −4 hr −1 , and a deactivation rate constant based on surface area of less than 0.01 days −1 at 900° C.
38 . A process for converting N 2 O to nitrogen and oxygen comprising contacting the N 2 O with a catalyst composition which comprises nickel oxide, cobalt oxide or a combination thereof on a zirconia substrate, the catalyst composition having surface area of about 1 to about 100 m 2 /g after exposure to a calcination temperature of between about 400° C. and about 950° C.
39 . A process of claim 38 , wherein the catalyst composition has surface area of about 2 to about 30 m 2 /g after exposure to a calcination temperature of between about 400° C. and about 950° C.