Combination and Integration of DPF-SCR Aftertreatment ...Combination and Integration of DPF – SCR Aftertreatment Technologies Kenneth G. Rappé Pacific Northwest National Laboratory

Combination and Integration of

DPF – SCR Aftertreatment Technologies

Kenneth G. Rappé Pacific Northwest National Laboratory (PNNL)

May 16, 2012 ACE025

This presentation does not contain any proprietary, confidential, or otherwise restricted information

Annual Merit Review and Peer Evaluation

May 16, 2012

PNNL/PACCAR DPF–SCR AFTERTREATMENT INTEGRATION

OVERVIEW

Start – Oct 2008 Finish – Sept 2012

Barriers addressed Heavy truck thermal efficiency Cost effective emission control Combined NOx and PM emissions

• Total planned project funding – $1.6M DOE share – $1.6M I.K. Contractor share

• $875K received through FY11

Timeline

Budget

Barriers

• Primary Partner: PACCAR • PACCAR Technical Center

• DAF Trucks (operating as an extension of PACCAR) • Utrecht Univ. supporting DAF

• Project Lead: PNNL

Partners


May 16, 2012


RELEVANCE

Objective is to fundamentally understand the integration of SCR & DPF technologies for HDD Determine system limitations, define basic requirements for efficient/effective operation and integration with engine

Develop an understanding of … optimal loading of SCR catalyst for maximizing NOx reduction while maintaining acceptable ∆P and filtration performance proper thermal and reactive management of the system for efficient NOx reduction along with maximizing passive soot oxidation capacity

Motivation for integration: to target a reduction of cost and volume of the engine aftertreatment systems via inclusion of SCR and DPF functionalities into a single entity.


May 16, 2012


MILESTONES Demonstrate integrated DPF/SCR on 2 cm dia. elevated porosity filter (19 mo.) – complete

Discussions with manufacturer on pathway to fabricate integrated DPF/SCR for vehicle demonstration (33 mo.) – complete

Demonstrate performance of an integrated DPF/SCR system on an elevated porosity wall-flow filter sample on a diesel engine exhaust slip stream (39 mo.) – complete

Demonstrate a 15+ cm diameter coated wall flow integrated DPF/SCR system can be prepared that has similar dispersion of catalyst(s) as a ~2 cm diameter wall flow coated filter – later this year

Demonstrate performance of an integrated DPF/SCR wall-flow filter on diesel engine (48 mo.) – later this year [engine (DAF) and truck** (PACCAR)]; **pending successful engine demonstration


May 16, 2012


APPROACH/STRATEGY First key barrier to successful system implementation: ∆P

Solutions: 1. Higher porosity substrate 2. Refined wash-coating technique

1. High porosity (UHP) substrate Cordierite: Corning developmental UHP substrate Aspiring to include SiC, ACM in engine slip-stream investigations

2. BASF refined wash coating technology Multiple iterations of coated parts acquired for study Good working relationship with BASF’s HD Systems R&D group


May 16, 2012


APPROACH/STRATEGY Highly evolving field of work (mostly LDD, some HDD)* This effort currently focused on:

Optimizing SCR catalyst washcoat Facilitating passive soot oxidation

Working relationship with BASF (HD Systems Development) SCR catalyst (Cu/Z) expertise Washcoating, manufacturability UHP cordierite substrate sample coating (cores, bricks)

Flow restriction concerns ∆P: SCR/DPF > SCR + cDPF (demonstrated by prior efforts)

Maximize NOx reduction performance, maximize PM filtration performance, and minimize flow restriction simultaneously is the challenge

*see back-up slides for overview of recent field of work


May 16, 2012



May 16, 2012


TECHNICAL ACCOMPLISHMENTS

0

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0 1 2 3 4 5

Pres

sure

Dro

p, k

Pa

Accumulated Soot, g/L

∆P after initial loading phase~11.5 kPa @ ~0.5 g/L soot

Upstream 90 g/L SCR catalyst

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Downstream 90 g/L SCR catalyst

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Downstream 150 g/L SCR catalyst

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Upstream

150 g/L SCR Catalyst

(2003 Jetta, ~300°C, 55k GHSV)

Both amount and location of SCR catalyst have measureable significant impact on dynamic permeability of filter during soot loading


May 16, 2012


TECHNICAL ACCOMPLISHMENTS Modeling of wall-scale transport effects

Single flat wall with exhaust approaching in the normal direction Channel scale transport effects & axial variations are ignored Simplified SCR reaction network developed at PNNL for current Cu-CHA SCR catalyst Commercial flow-through parts used to develop SCR model loaded to ~170 g/L Simplified porous media with similar porosity and tortuosity of the SCRF used in experiments 90 g/L of catalyst distributed evenly throughout the porous wall + 60 g/L placed on down-stream wall surface Soot oxidation kinetic model by Messerer et al, 2006 Assumed fresh (very reactive) soot Conclusions dependent upon validity of assumptions and kinetics used

350°

C 4 g/L soot

150 g/L catalyst 500 ppm NO2 500 ppm NO

35,000 GHSV ANR = 1


May 16, 2012


TECHNICAL ACCOMPLISHMENTS Modeling of wall-scale transport effects

SCR reduces soot oxidation rate by lowering upstream NO2 concentrations A mild NO2 gradient exists across the porous SCRF wall, indicating that catalyst placement on the downstream side of the wall is somewhat advantageous

With SCR NO2 [ppm] NO [ppm] NO2 rate

Outlet: 6 ppm NO2 46 ppm NO 33 ppm NH3

Soot oxidation: 8.9 g/s L NOx reduction: 95%

No SCR NO2 [ppm] NO [ppm]

Outlet: 40 ppm NO2 960 ppm NO

Soot oxidation: 11.3 g/s L NOx reduction: 0%

NH3 [ppm]

40 ppm 28 ppm

12 ppm


May 16, 2012


TECHNICAL ACCOMPLISHMENTS Pulsed Oxidation Studies – 150 g/L SCR catalyst

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ive;

NRE

Time, relative

w/o

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w/o

SCR

w/S

CR

w/S

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w/S

CR

~280°C ~320°C ~350°C

w/o

SCR

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ive;

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Time, relativew

/o S

CR

w/o

SCR

w/o

SCR

w/S

CR

w/

SCR

w/S

CR

~280°C ~320°C ~350°C

200 ppm NO2 500 ppm NO2

Effect of NO2 concentration – 200 ppm (left) versus 500 ppm (right) 1000 ppm NOx, ANR = 1, 35k GHSV Increased NO2 minimizes PSO-inhibiting effect of SCR processes


May 16, 2012


TECHNICAL ACCOMPLISHMENTS Pulsed Oxidation Studies

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elat

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Time, relative

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CR

w/

SCR

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SCR

~280°C ~320°C ~350°C

w/o

SCR

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2+CO

], pp

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dP, r

elat

ive;

NRE

Time, relativew

/o S

CR

w/o

SCR

w/o

SCR

w/S

CR

w/

SCR

w/S

CR

~280°C ~320°C ~350°C

90 g/L SCR catalyst 150 g/L SCR catalyst

Effect of catalyst loading – 90 g/L (left) versus 150 g/L (right) 500 ppm NO2, 1000 ppm NOX, ANR = 1, 35k GHSV Increased PSO observed <350°

C with 90 g/L versus 150 g/L


May 16, 2012


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Pres

sure

Dro

p, re

lativ

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Temperature, °C

90 g/L catalyst; 500 ppm NO2; 35k GHSV

NO2/NOx=0.33; PSO+SCRNO2/NOx=0.33; PSONO2/NOx=0.5; PSO+SCRNO2/NOx=0.5; PSO

SCR - selective catalytic reductionPSO - passive soot oxidation

TECHNICAL ACCOMPLISHMENTS TPO – Temperature Programmed Oxidation

Negligible impact of NO2/NOx fraction <0.5

Passive soot oxidation retardation ~40°

C

4 g/L soot loading ANR = 1

0%10%20%30%40%50%60%70%80%90%

100%

200 250 300 350 400 450 500

NRE

Temperature, °C

NO2/NOx = 0.33NO2/NOx = 0.5

90 g/L catalyst


May 16, 2012


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Temperature, °C

150 g/L catalyst; 500 ppm NO2; 35k GHSV

NO2/NOx=0.5; PSO+SCRNO2/NOx=0.5; PSONO2/NOx=0.65; PSO+SCRNO2/NOx=0.65; PSO


TECHNICAL ACCOMPLISHMENTS TPO – Temperature Programmed Oxidation

Significantly less retardation of passive soot oxidation at NO2/NOx fraction >0.5

ANR = 1 4 g/L soot loading

0%10%20%30%40%50%60%70%80%90%

100%

200 250 300 350 400 450 500

NRE

Temperature, °C

NO2/NOx = 0.5NO2/NOx = 0.65

150 g/L catalyst


May 16, 2012


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NO2/NOx = 0.5; 500 ppm NO2; 35k GHSV

150 g/L - PSO+SCR150 g/L - PSO90 g/L - PSO+SCR90 g/L - PSO


TECHNICAL ACCOMPLISHMENTS

90 g/L SCR catalyst exhibits less retardation of PSO (~40°

C) versus 150

g/L (~60°

C)

Indicates potential optimum catalyst loading target exists for facilitating PSO

ANR = 1

TPO – Temperature Programmed Oxidation

4 g/L soot loading

0%10%20%30%40%50%60%70%80%90%

100%

200 250 300 350 400 450 500

NRE

Temperature, °C

150 g/L90 g/L

NO2/NOx = 0.5


May 16, 2012


TECHNICAL ACCOMPLISHMENTS Diesel engine slipstream testing **

Balance point temperature (BPT) analysis; 60 g/L SCR catalyst ANR = 0 (i.e. no SCR reaction); BPT ~ 360°C

300 ppm NOx

NO2/NOx ~40% ~73k GHSV

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** See technical back-up slides for experimental configuration

Comparing to tested DAF engine + aftertreatment High NOx engine-out settings: 300 ppm NOx; 40% NO2; BPT 340–360°

C

Low NOx engine-out settings: 150 ppm NOx; 40% NO2; BPT 380–400

C


May 16, 2012


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Time, min

TECHNICAL ACCOMPLISHMENTS Diesel engine slipstream testing

Balance point temperature (BPT) analysis ; 60 g/L SCR catalyst ANR = 1.0; BPT ~ 440°C

SCR reaction exhibits significant retarding effect on PSO process

@ ANR = 1: BPT > ~80°

C

40%

50%

60%

70%

80%

90%

100%

200 300 400 500 600N

RETemperature, °C

ANR = 1


May 16, 2012


TECHNICAL ACCOMPLISHMENTS Diesel engine slipstream testing

Balance point temperature (BPT) analysis ; 60 g/L SCR catalyst ANR = 0.85; BPT ~ 400°C Slight benefiting effect

of ANR adjustment for improving PSO in presence of SCR

@ ANR = 0.85: BPT > ~40°

C

40%

50%

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70%

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200 300 400 500 600N

RETemperature, °C

ANR = 0.85ANR = 1200

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Time, min


May 16, 2012


COLLABORATIONS

Partners PACCAR & DAF Trucks (Industry): CRADA partner, provide engine and exhaust data used in experimental study; monthly teleconferences discussing progress and results of work

University of Utrecht (Academic): linking active site characteristics of developmental zeolites to deNOx activity and selectivity, characterizing deactivation phenomena; monthly teleconference participant discussing progress and results of research

BASF (Industry): integrated SCR/DPF parts supplier, providing wash-coating expertise and 2012 production SCR catalyst active phase

Corning (Industry): developmental high porosity cordierite supplier


May 16, 2012


FUTURE WORK (2012) Continue system kinetic and performance investigations

Both simulated exhaust and on engine slipstream Detailed examination of SCR & PSO interactions Evaluation of reductant dosing strategies for improving PSO

e.g. passive-active regeneration strategies

Full-scale engine testing beginning now Parts in hand, integrated with engine Three configurations investigated on engine

Reference – typical US2010 DOC–CDPF–SCR system System 1 – typical US2010 DOC + SCRF #1 System 2 – typical US2010 DOC + SCRF #2 NOTE: DOC specification can be changed based upon

NO to NO2 conversion efficiency

Testing consisting of the following Passive & active soot oxidation under non-SCR conditions Passive & active soot oxidation evaluation under SCR conditions NOx reduction efficiency of SCRF system

Study to include Characterization after de-greening on-engine 4 hours Characterization after accelerated aging at 650°C 100 hours


May 16, 2012


SUMMARY Impact areas

Optimizing SCR catalyst washcoat Facilitating passive soot oxidation

Optimizing SCR catalyst washcoat Amount and location of SCR catalyst have measureable impact on dynamic permeability of filter and catalyst efficacy Desired location on downstream portion of filter within porous microstructure

Facilitating passive soot oxidation of SCR/DPF couple Maximize NO2 concentration and fraction (of total NOx) Possible optimum catalyst loading target for maximizing PSO

To be interrogated further on engine slip-stream configuration With catalyst optimization & passive-active regeneration strategies, definite potential for deployment of DPF/SCR system with significant passive soot oxidation capacity


May 16, 2012


TECHNICAL BACK-UP SLIDES

TECHNICAL BACK-UP SLIDES


May 16, 2012


RECENT FIELD OF WORK

GM (SAE 2011-01-1140) – integrated system able to meet cert. requirements w/ significant reduction in A/T volume; coating process & wash-coat loading need optimization; approach does not address passive soot oxidation feasibility. JM (SAE 2011-01-1312) – addressed passive soot oxidation feasibility by turning EGR off. SCR/DPF with EGR off (elevated NOx) demonstrated improved passive regeneration capability. Ford (SAE 2010-01-1183) – oven aging tests indicate DOC-SCRF-SCR configuration able to meet T2B5 tailpipe NOx standards through 120k miles. BASF (Boorse et al, DEER 2010) – operating window (NOx conv., dP) determined by porosity, PSD. Filter type, porosity determines catalyst utilization.


May 16, 2012


ON-ENGINE SLIPSTREAM TESTING Engine operated steady-state Catalyst temperature increased via furnace

Oxycat

Heated CL NOx

AVL Smoke meter

NH3 dosing

Furnace DPF/SCR sample

T T

dP

Cummins ISB 235 5.9L

Documents

Combination and Integration of DPF-SCR Aftertreatment ...Combination and Integration of DPF – SCR Aftertreatment Technologies Kenneth G. Rappé Pacific Northwest National Laboratory