Development of New Diesel Oxidation and NH3 Slip Catalysts

Transcription

1 Downloaded from orbit.dtu.dk on: Feb 11, 218 Development of New Diesel Oxidation and NH3 Slip Catalysts Hansen, Thomas Klint; Jensen, Anker Degn; Hansen, Brian Brun; Janssens, Ton V.W. Publication date: 217 Document Version Publisher's PDF, also known as Version of record Link back to DTU Orbit Citation (APA): Hansen, T. K., Jensen, A. D., Hansen, B. B., & Janssens, T. V. W. (217). Development of New Diesel Oxidation and NH3 Slip Catalysts. Kgs. Lyngby: Technical University of Denmark (DTU). General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

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25 Air only Fuel Injection Exhaust Gas 1 2 Air Intake Compression 3 Expansion 4 Exhaust

26 3 x y + (x + y) x + y

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28 a x b x c a b 3 c x

29 Industrial processes and product use 49 % Road transport Agriculture 11 % Waste 1 % Agriculture Industrial 4 % processes and product use 3 % Non-road transport 7 % 39 % NMVOC Other % NO x Waste % Other % Energy production and distribution 9 % Energy use in industry 2 % Non-road transport 1 % Commercial, institutional and households 16 % Energy production and distribution 2 % Energy use in industry 13 % Commercial, institutional and households 14 % Industrial processes and product use 11 % Non-road transport 2 % Non-road transport 2 % On-Road transport 11 % On-Road transport 21 % On- On-Road transport 13 % Agriculture 3 % Agriculture Industrial 5 % processes and product use 1 % CO Waste 1 % Other % PM Waste 2 % Other % Energy production and distribution 3 % Energy use in industry 13 % Commercial, institutional and households 46 % Energy production and distribution 5 % Energy use in industry 7 % Commercial, institutional and households 56 % 37% NMVOC 5% 32% 16% 9% 1% CO 54% 32% 4% 6% 3% 1% 33% NO x 45% 39% 2% 22% % 4% PM 22% 27% 2% 3% 2% Gasoline, On-road Gasoline, Non-road Diesel, On-road Diesel, Non-road Other, Non-road Other, On-road / /

30 a b c c c c c c d e e a b > c d e 1 11 x

31 NA - naturally aspirated TC - turbocharged TCA - turbo, aftercooled EC - electr onic control NA Particulates, g/kwh EU 1992 US 1991 US 24 US 1998 TC TCA.1 EU 2 EC NOx, g/kwh x x No EGR Engine-out emissions NOx - PM trade-offs EGR PM Emissions DeNOx Euro VI Euro III Particulate Filter DeNOx DeNOx Euro IV Euro V NOx Emissions

32 Flow of Diesel Exhaust Gas Washcoat thickness Monolith substrate Monolith Substrate Cell pitch Catalyst coating Substrate wall thickness x x

33 1 1 Introduction to the Thesis an increase in the pressure drop across the DPF, and consequently, the filter must be regenerated [6, 32]. The DPF regeneration is done by burning off the accumulated soot particles. Filter regeneration can either be done actively (periodically) or passively (continuously) [6, 32, 33]. Active regeneration is done by injecting extra fuel to increase the exhaust gas temperature to above 6 C, at which point soot is rapidly oxidized by O2 [6, 33]. Passive regeneration relies on the ability of NO2 to oxidize soot at normal operating conditions and temperatures (3 4 C) of the exhaust system [6, 33, 34]. If sufficient NO2 is produced, the accumulation of soot in the filter can be balanced continuously by the rate of soot oxidation with NO2, without a net accumulation of soot over time [6]. The NO2 needed for passive regeneration can be generated in the DOC. Alternatively, a catalyzed diesel particulate filter (cdpf), in which the filter walls are impregnated with a catalyst (e.g. Pt), can be used to generate the necessary NO2 for soot oxidation [6, 33, 35]. Control Unit for Urea Dosage: The control unit applies principals of process regulation and tailpipe measurements of NH3 and/or NOx concentrations to dose an aqueous solution of urea (CO(NH2 )2 ) into the hot exhaust gas [36]. The water evaporates and urea thermally decomposes, via the formation and subsequent hydrolysis of isocyanic acid, to two molecules of NH3. The resulting NH3 is used as the reducing agent in the selective catalytic reduction of NOx to N2 and H2 O [36, 37]. Selective Catalytic Reduction (SCR) of NOx : The selective catalytic reduction of NOx with NH3 and O2 (NH3 -SCR) to N2 and H2 O is used to remove NOx from the exhaust gas. The SCR reactions are commonly catalyzed by V2 O5 WO3 /TiO2, Cu-zeolites, or Fe-zeolites [6, 38, 39]. Usually, a slight stoichiometric excess of NH3 between 1 2% is used, since the SCR reaction becomes more efficient under these conditions, but this also results in an NH3 slip from the SCR catalyst [36, 38]. A mixture of NO with some NO2, generated upstream in the DOC or cdpf, also increases the rate of the NH3 -SCR reactions [6, 38, 39]. Ammonia Slip Catalyst (ASC): The excess NH3 in the exhaust gas is removed by selective catalytic oxidation (SCO) with oxygen to N2 and H2 O. The ASC commonly uses a Pt-based catalyst to provide the ammonia oxidation (AMOX) activity, combined with an NH3 -SCR catalyst to increase N2 selectivity [6, 38, 4]. A B Figure 1.8: A) A state-of-the-art diesel exhaust aftertreament system [6]. B) Illustration of the wall-flow filter used for the Diesel Particulate Filter [29].

34 1 Diesel Engine 4 Control Unit Urea 2 3 Injection 5 6 DOC DPF SCR ASC 7 NO 2 NO CO HC PM NO x CO HC PM NO x CO HC PM NO x NH 3 The Diesel Engine combusts fuel and regulated emissions (CO, HC, PM, NO x ) are formed and exit in the exhaust gas. The Diesel Oxidation Catalyst (DOC) oxidizes CO and HC to CO 2, and some NO to NO 2, to be used in DPF and SCR. The Diesel Particulate Filter (DPF) entraps PM (soot) and oxidizes it to CO 2 during regeneration using O 2 or NO 2. The Control Unit regulates the dosage of urea solution into exhaust gas. Urea decomposes to the NH 3 needed for SCR CO HC PM NO x NH 3 CO HC PM NO x NH 3 Selective Catalytic Reduction (SCR) unit uses NH 3 as reducing agent for catalytic reduction of NO x to N 2. Activity increased by mixture of NO and some NO 2. Excess NH 3 dosed to the SCR unit to increase NO x reduction is oxidized by the Ammonia Slip Catalyst (ASC) to N 2. The treated exhaust gas exits the aftertreatment system and is released into the atmosphere, now meeting the emission regulations on CO, HC, PM, NO x, and NH 3.

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45 Diesel Engine Urea/NH 3 Injection DOC DPF NH 3 -SCR ASC x 3 x x x

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48 DP t dp t NCO ads ads P t

49 N N D N D = N N 1 = N N 1 N d V 3 A 2 ρ N A 2 6 d = 6 V /A = ρ N A

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53 Probability Density Sample C Count: 169 = 2. 5 nm = 1 nm Particle Diameter (nm) 8 Probability Density Sample D Count: 8 = 2. 8 nm = 1 nm Pt Particle size (nm) 8 Probability Density Sample I Count: 19 = 23 nm = 14 nm Particle Diameter (nm)

54 a) CO Conversion (%) D 3.2 F 2.1 C 2.1 SA1 1.6 B 1.3 A 4.5 SA I b) C 3 H 6 Conversion (%) F 2.7 D 2.1 SA1 2.1 C 4.5 SA2 1.6 B 18.7 I 1.3 A c) NO Conversion (%) SA1 2.7 D 3. E 4.3 G 3.2 F 2.1 C 4.5 SA2 7.7 H 18.7 I 1.6 B 1.3 A NO - NO 2 Equilibrium

55 T 5 T 2 T 5 T 2 T 5 T 2 T 5 T 5 T 5 T 5 T 2 T 2 T 2

56 a) 14 T 5 for CO Oxidation ( C) b) T 5 for C 3 H 6 Oxidation ( C) c) T 2 for NO Oxidation ( C) Pt Particle Size (nm) Pt Particle Size (nm) st Cooling 2nd Heating 2nd Cooling 1st Cooling 2nd Heating 2nd Cooling 1st Cooling Pt Particle Size (nm) T 5 T 2

57 r N N r

58 a) b) c) CO TOF (mol CO*1-4 /s*mmol CO ads ) r'co Ox. (mol CO*1-4 /s*g Pt ) C 3 H 6 TOF (mol C 3 H 6 *1-4 /s*mmol CO ads ) r'c3h6 Ox. (mol C 3 H 6 *1-4 /s*g Pt ) NO TOF (mol NO*1-4 /s*mmol CO ads ) r'no Ox. (mol NO*1-4 /s*g Pt ) Pt Particle Size (nm) Pt Particle Size (nm) (nm) TOF@19 C - Under 1% Conv. Rate of reaction@19 C CO Adsorption Capacity 4 2 TOF@5 C - Under 1% Conv. Rate of reaction@5 C CO Adsorption Capacity TOF@15 C - Under 1% Conv. Rate of reaction@15 C CO Adsorption Capacity Pt Particle Size (nm) r r N CO ads (mmol CO ads /g Pt ) N CO ads (mmol CO ads /g Pt ) N CO ads (mmol CO ads /g Pt )

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60 % of Atoms # of Atoms (mmol/g Pt ) Pt Particle Diameter (nm) % Corner Atoms % Edge Atoms % Terrace Atoms # of Surface Atoms # of Corner Atoms # of Edge Atoms # of Terrace Atoms

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74 a) NH 3 Conversion (%) wt.% Pt/Al 2 O 3 1 wt.% Pt/Al 2 O 3 5 wt.% Rh/Al 2 O 3 5 wt.% Pd/Al 2 O b) 1 d) c) NO x Yield (%) NO x Yield NO 2 Yield N 2 Yield (%) 5 N 2 O Yield (%) x ± x x x x x x

75 x T 5 a) NH 3 Conversion (%) b) N 2 Yield (%) 1 5 ~2 nm 1.3 nm ~2 nm T 5 ( C) Pt Particle Size (nm) c) NO x Yield (%) d) N 2 O Yield (%) 1 5 NO x Yields: nm NO x Yield: ~2 nm 7.7 nm 1.3 nm NO 2 Yields 1.3 SA, 2.7, 4.3 nm 18.7 nm ~2 nm nm 1.3 nm 1.3 nm SA 2.7 nm 4.3 nm 7.7 nm 18.7 nm ~2 nm 1.3 nm ~2 nm x ± 5 2 T 5

76 T 5 x x x x x x x x x a) Ratio: NO 2 / NO x nm 4.3nm 1.3nmSA 7.7nm 1.3nm 18.7nm ~2nm b) Max. Ratio of NO 2 / NO x Particle Size (nm) x x

77 x x T 5 x p /p = p /p = 2

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88 x x A) Single Layer AMOX (SL-AMOX) NH 3 NO x N 2 + N 2 O C) Dual Layer (DL) NH 3 N 2 + N 2 O SCR Catalyst NH 3 + NO x N 2 + N 2 O AMOX Catalyst NH 3 NO x + N 2 O + N 2 Monolith Wall AMOX Catalyst Monolith Wall NH 3 NO x + N 2 + N 2 O B) Single Mixed Layer (SML) NH 3 NO x N 2 + N 2 O D) Hybrid Dual Layer (HDL) NH 3 N 2 + N 2 O SCR Catalyst NH 3 + NO x N 2 + N 2 O AMOX Catalyst + SCR Catalyst NH 3 NO x + N 2 + N 2 O NH 3 + NO x N 2 + N 2 O AMOX Catalyst + SCR Catalyst NH 3 NO x + N 2 + N 2 O NH 3 + NO x N 2 + N 2 O Monolith Wall Monolith Wall x x x x x x x

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92 1 A j E,j i = = (y(a j, E,j ),i y,i ) 2 A j, E,j i C 3 i Q C i W = R i Q 3 W R i i i C i p i C i = p i R T θ i Ω i t i Ω i θ i i i N r R,i = ν i,j r j(p i, θ i, T ) j=1

93 ν i,j i j r j j p k j ( ) E,j k j = A j R T A j E,j R T

94 Aj E,j k p (1 θ) k θ k θ 2. 1 k θ k θ p k p p k p k = k K K A A A A A A A 3 2

95 + [ ] x LT x HT = 1 x LT ( ) H T S K x = R T H S x x x x x = K,x x = 1 x

96 j d,j a k p P T (1 θ) ρ 1 a k θ ρ (1.97 θ) k θ b k p p b k p k θ p x + k θ p x k θp x + k θ p x k θ p k θ p k θ p p k θ p p c x x k x k x a 3 ρ b k = k/k K c k /k = K x = ( H T S /RT) H = S = d A A d A A A A A A d A 3 2 d A A 2

97 NH 3 NO x N 2 + N 2 O AMOX Catalyst + SCR Catalyst AMOX Catalyst + SCR Catalyst NH 3 NO x + N 2 + N 2 O NH 3 + NO x N 2 + N 2 O NH 3 NO x + N 2 + N 2 O NH 3 + NO x N 2 + N 2 O Monolith Wall Q C,i,k 1 Q C,i,k = k,i A (C,i,k C,i,k ) Q 3 A 3 i k C,i,k 1 C,i,k 3 i C,i,k i k,i i D,i 2 d Sh k,i = D,i Sh d

98 T T T T Sh = Sh (1 z).545 ( 48.2 z) Sh z z x u x z = x D,i u x d 2 D,i 2 C,i r 2 + ( ϕ ρ R,i ) = i R,i ρ 3 ρ = ρ = ϕ = ϕ = 1 ϕ =.5 C,i D i r = k,i A (C,i,k C,i,k ) C,i r =

99 C,i D,i C,i r = D,i r C,i = C,i D D,i = ϵ ( ) 1 1 τ 1 + D,i D,i ϵ τ D,i D M,i i d D,i = d 3 8 R T M,i π d

100 1 /2 5 Concentration (ppm) NH 3 NO NO 2 N 2 O N

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102 A 6 5 NH 3 Oxidation D 6 5 Standard SCR (NO 2 /NO x =) Concentration (ppm) NH 3 NO NO 2 N 2 O N 2 Concentration (ppm) NH 3 NO NO 2 N 2 O N B NO Oxidation 5 E Slow SCR (NO 2 /NO x =1) 5 Concentration (ppm) NO NO 2 Concentration (ppm) NH 3 NO NO 2 N 2 O N C NO 2 Decomposition F Fast SCR (NO 2 /NO x =.5) 5 Concentration (ppm) NO NO 2 Concentration (ppm) NH 3 NO NO 2 N 2 O N

103 x NO x Conversion (%) Fraction of Catalyst in LT State or HT State (%) Standard SCR (NO 2 /NO x = ) NO x Conversion LT Fraction (x LT ) HT Fraction (x HT ) x x x x x x 9 x x

104 a) NH 3 Concentration (ppm) b) N 2 Concentration (ppm) c) NO x Concentration (ppm) d) N 2 O Concentration (ppm) SL-AMOX SL-SCR SML DL D = D =

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118 ½ 1) Single Layer AMOX (SL-AMOX) NH 3 NO x N 2 + N 2 O 2) Single Layer SCR (SL-SCR) NH 3 N 2 AMOX Catalyst NH 3 NO x + N 2 O + N 2 Monolith Wall SCR Catalyst NH 3 N 2 Monolith Wall 3) Dual Layer (DL) NH 3 N 2 + N 2 O 4) Inverse Dual Layer (IDL) NH 3 NO x N 2 + N 2 O SCR Catalyst NH 3 + NO x N 2 + N 2 O AMOX Catalyst NH 3 NO x + N 2 + N 2 O AMOX Catalyst NH 3 NO x + N 2 + N 2 O SCR Catalyst NH 3 + NO x N 2 + N 2 O Monolith Wall Monolith Wall 5) Hybrid Dual Layer SCR Split (HDL-S) NH 3 N 2 + N 2 O 6) Inverse Hybrid Dual Layer SCR Split (IHDL-S) NH 3 NO x N 2 + N 2 O SCR Catalyst AMOX Catalyst + SCR Catalyst NH 3 + NO x N 2 + N 2 O NH 3 NO x + N 2 + N 2 O NH 3 + NO x N 2 + N 2 O AMOX Catalyst + SCR Catalyst SCR Catalyst NH 3 NO x + N 2 + N 2 O NH 3 + NO x N 2 + N 2 O NH 3 + NO x N 2 + N 2 O Monolith Wall 7) Hybrid Dual Layer AMOX Split (HDL-A) NH 3 NO x N 2 + N 2 O H) Monolith Inverse Wall Hybrid Dual Layer AMOX Split (IHDL-A) 8) Inverse Hybrid Dual Layer AMOX Split (IHDL-A) NH 3 NO x N 2 + N 2 O AMOX Catalyst AMOX Catalyst + SCR Catalyst NH 3 NO x + N 2 + N 2 O NH 3 NO x + N 2 + N 2 O NH 3 + NO x N 2 + N 2 O AMOX Catalyst + SCR Catalyst AMOX Catalyst NH 3 NO x + N 2 + N 2 O NH 3 + NO x N 2 + N 2 O NH 3 NO x + N 2 + N 2 O Monolith Wall Monolith Wall 9) Single Mixed Layer (SML) 1) Dual Mixed Layers (DML) NH 3 NO x N 2 + N 2 O NH 3 NO x N 2 + N 2 O AMOX Catalyst + SCR Catalyst NH 3 NO x + N 2 + N 2 O NH 3 + NO x N 2 + N 2 O AMOX Catalyst + SCR Catalyst NH 3 NO x + N 2 + N 2 O NH 3 + NO x N 2 + N 2 O AMOX Catalyst + SCR Catalyst NH 3 NO x + N 2 + N 2 O NH 3 + NO x N 2 + N 2 O Monolith Wall Monolith Wall

119 ϵ =.4 τ = d d

120 x x x k k x X = [ ] [ ] [ ] 2 [ ] S = [ ] [ ] 2 [ ] out S = [ ] in [ ] out [ x ] x S x = [ ] [ ] x x x x x x x χ ψ ψ d

121 x ψ, ψ, d, d χ [ ] + [ x ] + 2 [ ] n

122 Create initial population of parents: - User de ned - Randomly generated (bound) Evaluate tness of each individual of population a) Fit solution Select parents based on tness evaluation Generate nal Pareto front and evaluate ASC con guration

123 k k x x x x

124 NH 3 Conversion (%) N 2 Selectivity (%) NO x Selectivity (%) N 2 O Selectivity (%) SL-AMOX SML DL χ ψ ψ 1

125 + + + x x x x x x x x

126 N 2 Selectivity (%) NO x Selectivity (%) N 2 O Selectivity (%) NH 3 Conversion (%) SL-AMOX SML DL ψ χ ψ 1

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128 NH 3 Conversion (%) N 2 Selectivity (%) NO x Selectivity (%) N 2 O Selectivity (%) SML DL ψ ψ ψ χ 1

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130 NH 3 Conversion (%) N 2 Selectivity (%) SL-AMOX SML DL NO x Selectivity (%) N 2 O Selectivity (%) ψ χ ψ 1

131 NH 3 Conversion (%) DL: d p,bl = d dp,tl DL: d p,tl = 5 nm DL: d p,bl = 5 nm N 2 Selectivity (%) NO x Selectivity (%) N 2 O Selectivity (%) ψ χ ψ 1

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133 x x k k x k x k x x x x k

134 NH 3 Conversion (%) 1 x k NO ox. 1 x k NO ox x k NO ox. 8 x k NO ox. 16 x k NO ox. 32 x k NO ox SL-AMOX SML DL N 2 Selectivity (%) NO x Selectivity (%) 5 NO 2 Select N 2 O Selectivity (%) k x ψ χ ψ 1

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136 NH 3 Conversion (%) N 2 Selectivity (%) NO x Selectivity (%) N 2 O Selectivity (%) 1 5 Reference x k N2O, AMOX x k N2O, SCR SML DL k k ψ χ ψ 1

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138 NO x Slip (ppm) SL-AMOX SL-SCR DL IDL HDL-S IHDL-S HDL-A IHDL-A SML DML A NO x + 2*N 2 O Slip (ppm) C 2*N 2 O Slip (ppm) NH 3 Slip (ppm) B 2*N 2 Slip (ppm) NH 3 Slip (ppm) D NH 3 Slip (ppm) NH 3 Slip (ppm) 1

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151 p /p [ ] ] [ 2 A A A j [ ] 8. 2 j A [ 2] C i [ 3] C,i,k [ 3 ] C,i,k [ 3]

152 C,i,k [ 3] d [ ] D,i i [ 2 / ] D,i i [ 2 / ] D,i i [ 2 / ] d D d E,j [ ] [ ] [ ] j [] K x x [ ] K [ ] k j k,i M,i [ 3] i [] N r [ ] N [ / ] N [ ] N [ ] p i [] Q [ 3 / ] R r [ )] [ ] r [ )] R,i [/( )] S S S [ ] [ ] x [ ] Sh [ ] Sh [ ] T t T 2 T 5 [ ] [ ] [ ] [ ]

153 u x V [] ] [ 3 W [ ] x [ ] x [ ] x [ ] X y,i y,i [ ] [] [] z [ ] P i [] [ ] [ )] χ H S [ ] [ ] [ ] ϵ [ ] ν i i j [ ] Ω i [ ] ϕ [ ] ψ [] ρ [ 3] ] [ ρ τ [ ] θ i [ ] i j k i j k

154 a) CO Conversion (%) c) CO Conversion (%) SA A 1.3 A 3.2 F 2.7 D 3.2 F 1.6 B 2.7 D 2.1 C 2.1 C 4.5 SA I 1.6 B 4.5 SA I b) CO Conversion (%) d) CO Conversion (%) C SA1 2.7 D 3.2 F 3.2 F 1.6 B 1.3 A 4.5 SA I D 1.3 A 4.5 SA2 1.6 B 2.1 C 18.7 I

155 a) C 3 H 6 Conversion (%) SA1 4.5 SA I 3.2 F 2.7 D 2.1 C 1.3 A 1.6 B b) C 3 H 6 Conversion (%) SA1 4.5 SA2 3.2 F 2.7 D 18.7 I 1.3 A 1.6 B 2.1 C c) C 3 H 6 Conversion (%) SA2 2.7 D 3.2 F 18.7 I 1.3 A 1.6 B 2.1 C d) C 3 H 6 Conversion (%) SA2 3.2 F 2.7 D 18.7 I B A 2.1 C

156 a) NO Conversion (%) I 4.5 SA2 4.3 G 3.2 F 3. E 2.7 D 2.1 SA1 7.7 H NO - NO 2 Equilibrium 2.1 C 1.6 B 1.3 A b) NO Conversion (%) SA1 3. E 2.7 C 4.3 G 3.2 F 2.1 C 4.5 SA2 7.7 H 18.7 I 1.6 B 1.3 A NO - NO 2 Equilibrium a) NO Conversion (%) st Heat Up 1st Cool Down 2nd Heat Up 3rd Heat Up 2nd Cool Down 3rd Cool Down 4th Heat Up 4th Cool Down NO - NO 2 Equilibrium b) NO Conversion (%) st Heat Up 1st Cool Down 2nd Heat Up 3rd Heat Up 2nd Cool Down 3rd Cool Down NO - NO 2 Equilibrium

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158 Conv. / Yield (%) st Heating Conv. / Yield (%) st Cooling Conv. / Yield (%) nd Heating Conv. / Yield (%) nd Cooling X NH3 Y NO Y NO2 Y NOx Y N2O Y N2

159 1 1 Conv. / Yield (%) 5 1 st Heating Conv. / Yield (%) 5 1 st Cooling Conv. / Yield (%) nd Heating Conv. / Yield (%) nd Cooling X NH3 Y NO Y NO2 Y NOx Y N2O Y N2

160 Conv. / Yield (%) 1 5 X NH3 Y NO Y NO2 Y NOx Y N2O Y N2 1 st Heating Conv. / Yield (%) st Cooling Conv. / Yield (%) nd Heating Conv. / Yield (%) nd Cooling

161 Conv. / Yield (%) st Heating Conv. / Yield (%) 1 5 X NH3 Y NO Y NO2 Y NOx Y N2O Y N2 1 st Cooling Conv. / Yield (%) nd Heating Conv. / Yield (%) nd Cooling

162 x x a) NH 3 Conversion (%) wt.% Pt/Al 2 O 3 1 wt.% Pt/Al 2 O 3 5 wt.% Rh/Al 2 O 3 5 wt.% Pd/Al 2 O b) 1 d) c) NO x Selectivity (%) NO x Selectivity NO 2 Selectivity N 2 Selectivity (%) 5 N 2 O Selectivity (%) x

163 1 1 Conv. / Yield (%) 5 1 st Heating Conv. / Yield (%) 5 1 st Cooling Conv. / Yield (%) nd Heating Conv. / Yield (%) nd Cooling X NH3 Y NO Y NO2 Y NOx Y N2O Y N2

164 Conv. / Yield (%) st Heating Conv. / Yield (%) st Cooling Conv. / Yield (%) nd Heating Conv. / Yield (%) nd Cooling X NH3 Y NO Y NO2 Y NOx Y N2O Y N2

165 Conv. / Yield (%) st Heating Conv. / Yield (%) st Cooling Conv. / Yield (%) nd Heating Conv. / Yield (%) nd Cooling X NH3 Y NO Y NO2 Y NOx Y N2O Y N2

166 1 1 Conv. / Yield (%) 5 1 st Heating Conv. / Yield (%) 5 1 st Cooling Conv. / Yield (%) nd Heating Conv. / Yield (%) nd Cooling X NH3 Y NO Y NO2 Y NOx Y N2O Y N2

167 1 1 Conv. / Yield (%) 5 1 st Heating Conv. / Yield (%) 5 1 st Cooling Conv. / Yield (%) nd Heating Conv. / Yield (%) nd Cooling X NH3 Y NO Y NO2 Y NOx Y N2O Y N2

168 Conv. / Yield (%) st Heating Conv. / Yield (%) st Cooling Conv. / Yield (%) nd Heating Conv. / Yield (%) nd Cooling X NH3 Y NO Y NO2 Y NOx Y N2O Y N2

169 x NH 3 Conversion (%) SL-SCR - EXP SL-SCR - SIM NO x Selectivity (%) N 2 Selectivity (%) 5 N 2 O Selectivity (%) ψ 1

170