METHOD OF PREPARING A COPPER-PROMOTED ZEOLITE
The present disclosure provides a method for preparing a selective catalytic reduction (SCR) catalyst, the SCR catalyst comprises a metal ion-exchanged zeolite. A method uses an in-situ ion exchange process. A process includes admixing a zeolite in the ammonium (NH 4 + ) form with an aqueous mixture comprising water, a transition metal ion source, and, optionally, an acid, to form a slurry containing a metal ion-exchanged zeolite.
1 . A process for preparing a selective catalytic reduction catalyst comprising a transition metal ion-exchanged zeolite, wherein the process comprises
admixing an ammonium form zeolite with an aqueous mixture comprising a transition metal ion source, and, optionally, an acid, to form a slurry comprising a transition metal ion-exchanged zeolite.
2 . The process of claim 1 , wherein the transition metal is chosen from copper, manganese, iron, and combinations thereof.
3 . The process of claim 1 , wherein the transition metal ion source is a salt of the transition metal chosen from an oxide, nitrate, chloride, sulfate, acetate, hydroxide, oxalate, acetylacetonate, and carbonate.
4 . The process of claim 1 , wherein the transition metal ion source is copper oxide.
5 . The process of claim 1 , wherein the aqueous mixture comprises the acid and the acid is acetic acid.
6 . The process of claim 1 , wherein the zeolite has a framework type chosen from ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFX, AFY, AHT, ANA, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AVL, AWO, AWW, BCT, BEA, BEC, BIK, BOF, BOG, BOZ, BPH, BRE, BSV, CAN, CAS, CDO, CFI, CGF, CGS, CHA, CHI, CLO, CON, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EEI, EMT, EON, EPI, ERI, ESV, ETR, EUO, EZT, FAU, FER, FRA, GIS, GIU, GME, GON, GOO, HEU, IFR, IFY, IHW, IMF, IRN, ISV, ITE, ITG, ITH, ITW, IWR, IWS, IWV, IWW, JBW, JRY, JSR, JST, KFI, LAU, LEV, LIO, LIT, LOS, LOV, LTA, LTF, LTL, LTN, MAR, MAZ, MEI, MEL, MEP, MER, MFI, MFS, MON, MOR, MOZ, MRE, MSE, MSO, MTF, MTN, MTT, MVY, MTW, MWF, MWW, NAB, NAT, NES, NON, NPO, NPT, NSI, OBW, OFF, OKO, OSI, OSO, OWE, PAR, PAU, PCR, PHI, PON, PUN, RHO, RON, RRO, RSN, RTE, RTH, RUT, RWR, RWY, SAF, SAO, SAS, SAT, SAV, SBE, SBS, SBT, SCO, SEW, SFE, SFF, SFG, SFH, SFN, SFO, SFS, SFW, SGF, SGT, SIV, SOD, SOF, SOS, SSF, SSY, STF, STI, STO, STT, STW, SVR, SZR, TER, THO, TON, TSC, TUN, UEI, UFI, UOS, UOZ, USI, UTL, UWY, VET, VFI, VNI, VSV, WIE, WEN, YUG, ZON, and mixtures or intergrowths thereof.
7 . The process of claim 1 , wherein the zeolite has a framework type chosen from CHA and AEI.
8 . The process of claim 1 , wherein the zeolite has a CHA framework type.
9 . The process of claim 1 , wherein the zeolite is an aluminosilicate having a framework consisting of Si, Al, and O, wherein the molar ratio of SiO 2 :Al 2 O 3 in the framework is from about 2 to about 300, from about 10 to about 100, and/or from about 20 to about 50.
10 . The process of claim 1 , wherein the aqueous mixture further comprises a binder component.
11 . The process of claim 10 , wherein the binder component comprises at least one chosen from Al, Si, Ti, Zr, Ce, and mixtures thereof.
12 . The process of claim 10 , wherein the binder component is zirconium acetate.
13 . The process of claim 1 , wherein the aqueous mixture further comprises at least one additives chosen from a sugar, a dispersing agent, a surface tension reducer, a rheology modifier, and combinations thereof.
14 . The process of claim 1 , wherein the admixing occurs for a period of time from about 1 hour to about 48 hours, from about 12 to about 24 hours, for at least about 12 hours, or at least about 18 hours.
15 . The process of claim 1 , wherein the admixing is conducted at a temperature from about 10° C. to about 50° C., or from about 15° C. to about 25° C.
16 . The process of claim 1 , further comprising milling the aqueous mixture prior to and/or during the admixing.
17 . The process of claim 1 , further comprising adding a refractory metal oxide support material to the slurry following the admixing.
18 . The process of claim 1 , further comprising:
contacting a substrate with the slurry comprising the metal ion-exchanged zeolite to form a coating on the substrate, wherein the substrate comprises an inlet end, an outlet end, an axial length extending from the inlet end to the outlet end, and a plurality of passages defined by internal walls of the substrate extending therethrough;
drying the coated substrate;
calcining the coated substrate; and
optionally, repeating the contacting, drying, and calcining steps one or more times;
wherein the slurry is not filtered or washed prior to the contacting the substrate with the slurry.
19 . The process of claim 18 , wherein the drying is performed at a temperature from about 100° C. to about 150° C.
20 . The process of claim 18 , wherein the calcination is performed at a temperature from about 400° C. to about 600° C.
21 . The process of claim 1 , wherein the substrate is a flow-through substrate or a wall-flow filter.
22 . The process of claim 1 , wherein the transition metal ion-exchanged zeolite has an amount of transition metal ranging about 2 wt % to about 10 wt %, about 2.5 wt % to about 5.5 wt %, or about 3 wt % to about 5 wt %, based on a weight of the transition metal ion-exchanged zeolite and calculated as a transition metal oxide.