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. Careful debugging and analysis are needed to identify causes in FWCTM system when tail-pipe emissions do not meet the PM and PN targets.
The LDD segment is a niche market in China. It however has same level of technical complexity as in Europe when it comes to develop exhaust aftertreatment system to meet Stage 6. Technical trend and mainstream solution for China market are reviewed.
The HDD Stage VI is very similar to EU VI regulation. Due to uneven market application and diesel fuel quality, OEMs tend to adopt the conventional DOC+CSF+Cu-SCR system and use proven catalyst technologies. This paper discusses those durability concerns and reviews dedicated experiments for design validation, especially on effect of prolonged thermal aging and high sulfur fuel.
The off-road Stage IV standard has strong China attributes. Its gaseous emission limits are same as Europe Stage IIIB however it has a PN requirement not imposed until EU Stage V. This paper discusses possible off-road aftertreatment system pathways, with an emphasis on SCRoF for fit-for-market solution.