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Formaldehyde emissions of vehicles with combustion engines, burning oxygenated fuels are a major challenge for exhaust gas aftertreatment systems. This study shows the impact of such emissions for NH3-SCR, with a high NO2-ratio.

The progression of emission legislation has intensified the efforts of the automotive industry to develop improved exhaust gas after-treatment systems. The requirement to fulfill Euro 6d-TEMP in real-world driving scenarios, the already significant calibration effort for Euro 6d and the Euro 7 emission standards in discussion have significantly increased the work load for calibration engineers and the requirements for testing resources. Many original equipment manufacturers are implementing taskforces in order not to have to discard the planned start of production for their products, and some are even already forced to reduce their product portfolio. This is due to the diverse testing matrix required to cover all possible real driving emissions test scenarios. One big challenge is the extension and possible variation of boundary conditions regarding ambient temperatures, traffic conditions, road gradients and other varying driving resistances. Moreover, the test duration can cause considerable differences in the measured emissions, even if the same route is driven repeatedly. Addressing these challenges makes the application of a dedicated, event-targeted emission calibration mandatory. Since only a few sequences of the time-consuming road tests are relevant for improving the emission calibration, the methodology presented in this article focuses on the exact reproduction of these emission events on an emission chassis dynamometer with the aim of implementing calibratable solutions for these events. This is done using a real driving emission-cycle-generator which creates real driving emission compliant severe test scenarios and which focuses on the statistical relevance related to the typical product specific operation. The underlying generation process accesses a large database with real driving emission measurement results focusing on vehicle- or vehicle-group-specific challenges, using statistical approaches. It will be demonstrated how this procedure reduces test time and how it helps to tackle the substantial real driving emission work-load, while providing a dependable base to achieve real driving emission legislation compliance.

Catalysis letters (2021). doi:10.1007/s10562-021-03771-w, Published by Springer Science + Business Media B.V, Dordrecht [u.a.]

Catalysts : open access journal 11(11), 1339 (2021). doi:10.3390/catal11111339 special issue: "Special Issue "New Challenges in Electrocatalysts for Fuel Cells and Hydrogen Production" / Special Issue Editors: Dr. Davide Clematis, Guest Editor; Prof. Dr. Fabrice Mauvy, Guest Editor; Dr. Jan Van Herle", Published by MDPI, Basel

Gasoline particulate filters (GPF) recently entered the market and are already regarded as state-of-the-art for gasoline exhaust aftertreatment systems to enable EU6d-TEMP fulfillment and beyond. Due to its rapid market introduction, the field of GPF lifetime evaluation is still open for research. In this context, the paper describes the advantages of a method for accelerated investigation of filter ash loading during the development of particulate filters. The central task is the simulation of real-world lubrication oil consumption and combustion, which is the major source of ash in the exhaust gases. For that purpose, a burner test bench designed for catalyst aging was additionally equipped with an oil injection unit. The injection unit enables control of the oil volume and the droplet sizes as precursors for the ash particulates. The results obtained with the new filter aging method are compared with data from vehicle endurance runs and with burner test investigations in which the fuel is doped with oil. The latter method is currently considered as the state-of-the-art method for accelerated ash generation. The new method proofed to be vehicle-equivalent in terms of ash-induced backpressure, filtration efficiency, wall ash layer formation, and wall/plug ash ratio. In this context, it turned out that it is important not to atomize the oil droplets too far, since smallest particulates accumulate mainly at the walls and cause unrealistically high backpressures. Furthermore, the ash loading process should include different mass flows in order to achieve stable backpressure results.

Catalysts : open access journal 12(9), 953 (2022). doi:10.3390/catal12090953 special issue: "Special Issue "Catalytic Treatment of Air Pollutants (VOCs, PACs, PCDDs/PCDFs, Soot, NOx, CO) II" / Special Issue Editor: Dr. Fan Lin, Guest Editor; Prof. Dr. Jong-Ki Jeon, Guest Editor", Published by MDPI, Basel

The washcoat composition and the catalytic properties of two commercially available lean NOx traps (LNTs) were investigated. Both catalysts contained nominally the same NOx storage and catalytic materials but differed strongly in their amount and activity as well as in the composition of their layered washcoat architecture. In lean-rich cycle experiments under realistic engine-out gas compositions using a laboratory gas test bench, the LNTs showed comparable NOx storage behavior. At temperatures below 250 °C, the lean phase durations last up to 300 s until 50 % of the NOx storage capacity is reached. The simultaneously calculated NOx storage efficiencies drop rapidly below 35 %, resulting in a high NOx slip. Strong variations were observed in N2O and NH3 selectivity and in CO slip during regeneration of both LNTs caused by the different oxygen storage capacity (OSC), water gas shift (WGS) activity and rhodium distribution in the catalytic layers. Based on the obtained results, proposals were made to optimize the storage and regeneration performance, leading to highly efficient LNT catalysts for coupling with a downstream SCR catalyst.

The progression of emission legislations in Europe and China has increased the engagement of the automotive industry in the development of improved exhaust gas aftertreatment systems. The fulfillment of PN, NOx and expected CO limits in real world driving scenarios has led to the introduction of gasoline particulate filters, and moreover has significantly increased the work load for calibration engineers and on calibration testing resources. Many OEMs are in extreme task force modes to hold planned SOPs, and some were even forced to reduce their product portfolio. This is due to the large testing matrix, required to cover all possible Real Driving Emissions (RDE)-driving scenarios. This paper presents an RDE-cycle-generator to tackle the huge RDE work load. This RDE-cycle-generator is based on FEV’s large real driving emission measurement data base. It enables reproducibility and significantly cuts down testing effort, while representing a secure base to approve RDE legislation compliance.

The introduction of new emission legislations in Europe (EU6d-TEMP) and China (CN6b) increases the pressure on the automotive industry to develop new and better exhaust gas aftertreatment and combustion systems. The fulfilment of PN and NOx targets in real world driving scenarios and increasingly electrified powertrains have led to the introduction of gasoline particulate filters (GPFs) and enlarged catalytic converters. Now, on top of these major upgrades, the monitoring of CO emissions according to Real Driving Emissions (RDE) legislation puts a potential ban on high load enrichment for thermal component protection into focus. Hence, new technologies which enable Lambda 1 operation in the entire map of a gasoline engine are urgently required. This paper presents technology packages for component protection at high load stoichiometric operation as well as operational strategies for ultra-low CO emissions in all real driving scenarios. Assessed solutions span from base engine modifications to water injection and vehicle cooling concepts as well as to control functions. Favorable combinations are identified taking into consideration costs and realistic integration in ongoing vehicle programs.