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In order to clarify future automobile technologies and fuel qualities to improve air quality, second phase of Japan Clean Air Program (JCAPII) had been conducted from 2002 to 2007. Predicting improvement in air quality that might be attained by introducing new emission control technologies and determining fuel qualities required for the technologies is one of the main issues of this program. Unregulated material WG of JCAPII had studied unregulated emissions from gasoline and diesel engines. Eight gaseous hydrocarbons (HC), four Aldehydes and three polycyclic aromatic hydrocarbons (PAHs) were evaluated as unregulated emissions. Specifically, emissions of the following components were measured: 1,3-Butadiene, Benzene, Toluene, Xylene, Ethylbenzene, 1,3,5-Trimethyl-benzene, n-Hexane, Styrene as gaseous HCs, Formaldehyde, Acetaldehyde, Acrolein, Benzaldehyde as Aldehydes, and Benzo(a)pyrene, Benzo(b)fluoranthene, Benzo(k)fluoranthene as PAHs.

Influence of sulfur poisoning on NOx storage - reduction catalysts (NSR catalysts) was examined using both model gas and an actual vehicle. Deterioration of NSR catalysts is explained as the balance of sulfate formation in lean operating conditions and the amount of sulfate decomposed under rich operating conditions. This study focused on sulfate decomposition characteristics of NSR catalysts. First, sulfate decomposition characteristics of an NSR catalyst were examined in a model gas test. It was found that the initial temperature of SOx release was higher than the sulfur poisoning temperature. Crystal growth of sulfate by increasing temperature was assumed, and hence suppressed SOx release. Second, various sulfur concentrations (8 - 500 ppm) in gasoline were used for vehicle durability. The duration of one durability cycle was 1,260 seconds, including a 60 second regeneration of sulfur poisoning (AFR 14.2, 700 °C).