Uncombusted hydrocarbons

Ce02-supported noble-metal catalysts such as Pt, Pd and Rh are of interest because of their importance in the so-called three-way converter catalysts (TWC), designed to reduce emissions of CO, NOx and uncombusted hydrocarbons in the environment and to purify vehicle-exhaust emissions. Such catalysts are also of current interest in steam reforming of methane and other hydrocarbons. Conventional practical catalysts for steam reforming consist of nickel supported on a ceramic carrier with a low surface area and are used at high temperatures of 900 C. This catalyst suffers from coke formation which suppresses the intrinsic catalyst activity. Promoters such as Mo are added to suppress coke formation. Recently, Inui etal(l991) have developed a novel Ni-based composite... 

CO2 and H2O gas mixture present in an exhaust stream is about 0.02 bar, due to the presence of about 2% oxygen. The excess oxygen is present to ensure that there are no uncombusted hydrocarbons or CO. Another major difference is that a high fuel pressure is not required because the products of the combustion are not collected for further use. Tables 6.5 and 6.6 summarize the materials proper-... 

Kainz RJ, White EE. 1984. Depressant effects associated with the inhalation of uncombusted diesel vapor. In MacFarland HN, Holdsworth CE, MacGregor JA, et al., eds. Advances in modem environmental toxicology. Volume VI Applied toxicology of petroleum hydrocarbons. Princeton, NJ Princeton Scientific Publishers, Inc. 

Polycyclic aromatic hydrocarbons (PAHs) are produced during the incomplete combustion of organic material. PAHs can also be produced through natural, non-combustion processes, and they may be present in uncombusted petroleum. Uncombusted petroleum can be a direct source to the waters of... 

As discussed in Chapter 7, polluted air varies in composition from locale to locale and with the time of day and meteorological conditions in a given locale. Polluted urban air contains oxides of sulfur and nitrogen, carbon monoxide, ozone, uncombusted and partially combusted hydrocarbons from gasoline and diesel vehicles, and particulate matter. PM 2.5 particulates, the standard for evaluating pollution related to cardiovascular disease, are composed of combustion products, airborne soil, sulfates, nitrates, and heavy metals as listed in Table 29.4.141-45 ... 

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