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The in-line hydrocarbon (HC) adsorber is a passive after-treatment technology to address cold-start hydrocarbons in automotive engine exhaust gas. A major technical challenge of the in-line HC adsorber is the difference between the HC release temperature of the adsorber and the light-off temperature of the burn-off (BO) Catalyst. We call this phenomenon the “reversed-temperature difference”. To reduce the reversed temperature difference, NGK has proposed a new “In-line HC Adsorber System” which consists of light-off (LO) Catalyst + Barrel Zeolite Adsorber (BZA), with a hole through the center, BO Catalyst and secondary air injection management (SAE 970266). This, our latest paper, describes the evaluation of various adsorbents and the effect of the center hole on the Adsorber BZA. The adsorber system, which had the Adsorber BZA with a 25mm ϕ center hole and adsorbent coated, confirmed 30% lower FTP NMHC emission versus a system with no center hole or adsorbent coating.

It is well known that an EHC (Electrically Heated Catalyst) is very effective in reducing cold start HC emissions. However, the large electric power consumption of the EHC is a major technical issue. When installed in the exhaust manifold, the EHC can take advantage of exhaust heat to warm up faster, resulting in a reduced electric power demand. Therefore, a structurally durable EHC which can withstand the severe manifold conditions is desirable. Through the use of a extruded monolithic metal substrate, with a flexible hexagonal cell structure and a special canning method, we have succeeded in developing a structurally durable EHC. This new EHC installed in the exhaust manifold with a light-off catalyst directly behind it demonstrated a drastic reduction in FTP (Federal Test Procedure) Total HC emissions.

This paper proposes a high temperature manifold converter with a thin wall ceramic substrate, such as; 4mil/400cpsi and 4mil/600cpsi. Double-wall cone insulation design was proposed for close-coupled converters to protect the conventional intumescent mat from high temperature. However, the double wall cone insulation is not applicable when the converter is directly mounted to the exhaust manifold without an inlet cone. The prototype manifold converter was tested under hot vibration test with a non-intumescent ceramic fiber mat and retainer rings as a supplemental support. The converter demonstrated durability for 10 hours under 80G acceleration and 100 hours under 60G acceleration with 1,050 °C catalyst bed temperature. The skin temperature of the heat shield was kept below 400 °C.