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Over the past few years, China has made major legislative advancements on vehicle emissions, having set forth Stage 6 regulations for both LD and HD vehicles. To meet stricter standards, OEMs and associated suppliers of the exhaust aftertreatment value chain have gone through a period of unprecedented development. This paper selectively describes key challenges and highlights corresponding solutions of those development for both segments. In doing so, the authors wish to provide an overview of the catalyst systems used in upcoming China automobile market. A key challenge for LDG Stage 6 is the introduction of FWCTM (Four-Way Catalysts, aka cGPF - Coated Gasoline Particulate Filter). This paper discusses advantages and disadvantages of different system solutions. Experimental study showed oxygen and temperature are critical factors to achieve effective soot regeneration in a FWCTM.

The 4JB1 diesel engine originated from Isuzu has large share in the China light duty truck market. However, the tightened NOx emission target enforced by NS-V legislation compared with NS-IV regulatory standard is very challenging for this engine platform which originally adopted the DOC+POC catalyst layout. Furthermore, combustion characterization of this type engine leads to high soluble organic fraction (SOF) content in engine out particulates, which requires the catalysts in the exhaust after-treatment system (ATS) to deliver high SOF conversion efficiency in order to meet the regulation limit for particulate matters (PM). In this paper, an innovative exhaust catalyst layout with DOC+V-SCR is introduced. The front DOC is specially formulated with optimized PGM (Platinum Group Metal) loading which ensures effective SOF oxidation while keeping sulfuric acid and sulfate generation minimal.

Nowadays the Chinese legislative development and the implementation of advanced technologies to curb HDD emissions have been a subject of worldwide attention. Currently China is warping its efforts to deploy and enforce the launch of nationwide Stage IV and is also preparing for the setup and implementation of future regulation standards. Focus discussion here is on the aftertreatment pathways to meet China current and future emissions standards, based on market uniqueness. This paper seeks to provide retrospectives of the adoption of V-SCR on China stage IV HDD vehicles, through presenting findings from two separate postmortem analyses of field returned catalyst parts and also through comparative study with local catalyst products. The paper also discusses the challenges and possible solutions meeting the WHTC requirement for Stage IV and V city vehicles.