INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ InGas 18 months meeting May, 20th/21st 2010 Paris, France SPB2 INGAS 18 months meeting, Paris, 20./

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Contends Introduction of work Pd-TWC results Effect of H 2 O on CH 4 oxidation Methane Steam Reforming Secondary emissions Base characterizations, Lightoff T 50 Effect of hydrothermal aging Effect of Sulfur poisoning Summery Operation Strategy CH 4 and NO X abatement under stoichiometric conditions Summery NO X abatement under lean conditions Deriving of a Operation Strategy

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Experimental setup of the laboratory test system Exhaust air Evaporator H 2 O- Analytics detector Exhaust air Synth. gases Reactors Exhaust air Evaporator H 2 O- Analytics detector Exhaust air Synth. gases Reactors

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Introduction of work Synthetic gas tests with two test samples delivered by Ecocat. –Lightoff temperature T 50 Steady state temperature programs to heat up (10K/min) the catalyst and cool down after reaching 600°C. Measuring CO, CO 2, CH 4, NO X, NO, N 2 O, O 2, Lambda, NH 3, H 2 –Gasmix study 5 stationary temperatures with concentration programs to increase and decrease species concentration. Measuring CO, CO 2, CH 4, NO X, NO, N 2 O, O 2, Lambda, NH 3, H 2 –Hydrothermal aging Aging 10h at 800°C with water and air, aging 10h at 950°C with water and air. –Sulfur poisoning Sulfation at 300°C up to 1g/L catalyst sulfur. Desulfation with temperature program at Lambda = 1 (dT~10K/min up to 750°C) Desulfation with temperature program at Lambda = 0.9 (dT~10K/min up to 750°C)

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Effect of H 2 O on CH 4 oxidation H 2 O in gas-stream inhibits the CH 4 conversion. Engine exhaust contains ~12Vol.% H 2 O. CH 4 oxidation only with O 2 CH 4 oxidation only with NO CH 4 conversion with CO, CO 2, NO, O 2, H 2 in feed. with H 2 O w/o H 2 O

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Methane Steam Reforming In first step CH4 was formed to CO and 3H 2. Further the formed CO was converted by H 2 O to H 2 and CO 2. The water gas shift reaction with CO was activated at lower temperatures between 230°C and 350°C. Y CO = 0.6Vol.%, Y H2O = 10Vol.%Y CH4 = 1500ppm, Y H2O = 10Vol.%

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Secondary emissions At temperatures below 200°C CO has interaction with NO X and some NH3 was formed. When CH 4 has Lightoff at 420°C, about 100ppm NH 3 was formed. When CO react with NO X, some N 2 O was formed until CH 4 Lightoff. No significant N 2 O was formed during and after the CH 4 Lightoff at lambda=1.

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ SV=50000h Base-Characterizations SV=100000h -1 Gasmix 1 and 2 typify real gas concentration at corresponding engine load point. Temperature increase and decrease show hysteresis effect in concentrations. Gasmix-1 : CH 4 = 1500ppm*, CO=0.6Vol.%,H 2 =0.1Vol%, NO X =1300ppm, O 2 ~ 0.537Vol.%, H 2 O=10Vol%, CO 2 =10.7Vol.%, N 2 balance (Lambda = 1, SV~50000h -1 ) Gasmix-2 : CH 4 = 1000ppm*, CO=0.63Vol.%,H 2 =0.1Vol%, NO X =2600ppm, O 2 ~ Vol.%, H 2 O=10Vol%, CO 2 =10.7Vol.%, N 2 balance (Lambda = 1, SV~100000h -1 ) Sample condition: lambda = 1 gas compositon.

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Effect of hydrothermal aging „Basis“ means base-characterization with 600°C and lambda=1 aging. “Aging1” means characterization after 800°C hydrothermal aging. “Aging2” means characterization after 950°C hydrothermal aging. TWC has excellent durability against hydrothermal aging. SV = h -1 CH 4 Lightoff T 50 [°C] Tepm. increase Temp. decrease BasisAging 2 Aging 1 SV = h -1 CH 4 Lightoff T 50 [°C] Tepm. increase Temp. decrease BasisAging 2 Aging 1

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Effect of Sulfur poisoning “Aging1” means base-characterization after 800°C hydrothermal aging. “after sulfation” means characterization after 1g/L catalyst sulfation. “DeSO X 1” means characterization after Lambda=1 desulfation. (TPD up to 750°C) “DeSO X 2” means characterization after Lambda=0.9 desulfation. (TPD up to 750°C) Stoichiometric desulfation seems to remove the whole sulfur. SV = h -1 CH 4 Lightoff T 50 [°C] Temp. increase Temp. decrease after sulfation DeSOx 1DeSOx 2Aging 1 SV = h -1 CH 4 Lightoff T 50 [°C] Temp. increase Temp. decrease after sulfation Aging 1 DeSOx 1DeSOx 2

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Summery “Pd-TWC results” After 600°C the Lightoff temperatures are around 400°C. No critical secondary emissions were observed. Pd-TWC shows good resistance against hydrothermal aging. Lambda=1 desulfation seems the whole of sulfur removed. During cold start, the combustion should be adjusted so, that more CO and / or H 2 in the exhaust gas would be available.

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ CH 4 and NO X abatement under stoichiometric conditions Laboratory tests with synthetic gas test bench.

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Target for future emission standards To achieve the emission standards we need to improve the CH 4 conversion. To identify the best possible operation strategy a parameter study was done. The most sensitive parameter for three way operation was air/fuel ratio. The air/fuel ratio was varied by increasing the reducing agents. Lightoff - T 50 [°C] CH 4 mass in NEDC [g/km] NEDC cycle

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Impact of lambda variation (CO variation) T(°C)SV(h -1 )CH 4 (ppm)CO(Vol.%)NOx(ppm)O 2 (%)CO 2 (%)H 2 O(%) – ,7410,710 If upstream CO concentration increase, CH 4 conversion increase too (right picture). When CH 4 has been converted H 2 was detected. Increasing CO concentration increases H 2 forming proportional. (WGS reaction) upstream catalyst

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Impact of lambda variation (CO variation) It’s possible to increase the CH 4 conversion efficiency by increasing the CO concentration. The best CH 4 conversion has been reached between air/fuel ratios≤1. High level of H 2 has formed by steam reforming and watergas shift reactions. To investigate the role of the H 2 concentration in exhaust raw emissions, some tests with dosed H 2 were performed.

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ T(°C)SV(h-1)CH4(ppm)CO(ppm)NO x (ppm)O 2 (Vol%)CO 2 (Vol%)H 2 O(Vol%)λ +X.H 2 (Vol%) ,7410,7101,05 -0, ,34 H 2 has significant impact on CH 4 conversion too! Impact of lambda variation (H 2 variation) The dosed H 2 becomes oxidized in catalyst and increases the catalyst temperature. This oxidation of H 2 can be done with reducible reacting agents from the gas phase as well as oxidized agents from the catalyst surface.

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ CH 4 and NO X abatement under stoichiometric conditions A effective operation strategy can be summarized in some headwords: Ideal operation point is addicted to temperature and lambda. Rich engine operating mode during cold start can improve CH 4 conversion. After reaching CH 4 Lightoff, switch to normal stoichiometric engine operation mode.

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ The characterization of engine raw emissions at AVL The engine test bench results shows the possibility to increase the CO an H 2 concentration by engine calibration. The catalyst temperature can be increased by this way. This first engine test results show a positive trend regarding an effective engine cold start strategy.

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Summery To abate CH 4 and NO X under stoichiometric conditions its helpful: to realize slightly rich conditions during cold start. to increase the CO concentration in engine raw emissions. to increase the H 2 concentration in engine raw emissions. to increase the exhaust gas temperature.

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ NO X Abatement under lean conditions Under lean conditions the TWC can’t convert NO X. With the NSC we have the possibility to store the NO X during lean operation and convert them under rich conditions. To picture the NO X regeneration ability with CH 4, some systematic tests were performed. Periodic lean/rich switch (lean-time t=3min, rich-time t=20s) with different gas compositions at rich-cycle. 1st rich-gas mixture at Lambda=0.935 CH ppmH 2 O-12Vol.%CO Vol%N 2 balance 2nd rich-gas mixture at Lambda=0.94 CH ppmCO-0.35Vol%H 2 O-0Vol.%CO Vol%N 2 balance 3rd rich-gas mixture at Lambda=0.935 CH ppmCO-0.35Vol%H Vol%H 2 O-12Vol.%CO Vol%N 2 balance 4th rich-gas mixture at Lambda=0.935 CH ppmCO-0.35Vol%H Vol%H 2 O-12Vol.%CO Vol%N 2 balance

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Test result Ineffective NSC regeneration only with CO and CH 4 upstream-catalyst. No benefit because WGS and Steam Reforming reactions. If H 2 is present in feed upstream NSC good regeneration is possible at low temperatures. NSC material with ~130g/ft 3 Pt/Pd/Rh: 10/2/1 and aged 700°C. Its possible to trigger the H 2 -forming for NSC regeneration on a prelocated TWC. Only with high H 2 concentrations upstream, a NSC regeneration is possible.

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ NO X Abatement under lean conditions To regenerate the stored NO X under rich conditions H 2 upstream NSC is necessary. For a application together with an CNG engine, the H 2 can be provided by engine raw emissions at every engine load under rich conditions. If the NSC would be placed after TWC, the CO conversion by watergas shift under rich conditions can provide H2 additionally. Engine raw emissions + H 2 forming on TWC

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Deriving of a Operation Strategy At first it should be focussed on CH 4 abatement at cold start. The first part of the NEDC could be performed under slightly rich conditions with high CO and H 2 concentrations in exhaust gas, to increase the catalyst temperature. The second part could start after reaching CH 4 Lightoff temperature upstream TWC. Now we got nearly 100% CH 4 conversion and the focus can switch to NO X abatement under lean conditions. If the engine operation mode has been switched from slightly rich cold start mode to lean mode, a NSC can store the NO X during lean phases. If the NO X storage capacity is nearly at maximum, the NSC can be regenerated by a short rich phase. Depending on NSC volume and NO X engine emissions a specific number of lean/rich cycles have to be performed to achieve the NO X emission regulations.

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Backup

INGAS - Integrated GAS Powertrain Project number: Project number: DAIMLER AG INGAS 18 months meeting, Paris, 20./ Test-conditions When NO X outlet-concentration become steady state, the NO X storage level during adsorption (lean) reach his maximum. Then the reduced NO X mass in rich phase is the same amount becoming adsorbed in the next lean phase. The averaging over 5 cycles represents the regenerated NO X mass.