Exhaust gas components

As a fourth step, discussion continues for the introduction of emission limits for other exhaust gas components, and for particulate matter of diesel powered vehicles. For example, there has been discussion in the USA and some European countries on separate - additional - emission limits for carbon dioxide, benzene and/or aldehydes. In the USA there is a project to consider an additional ozone-formation factor to be allocated to the tailpipe emission of passenger cars. This is because each exhaust gas component has a different potential to contribute to atmospheric ozone formation. This potential is quantified according to the theory of Carter by the maximum incremental reactivity (MIR) factor, expressed as grams of... 

Table 4. Maximum incremental reactivity factor for some selected exhaust gas components.

Table 5. Exhaust gas components measured and the corresponding analyzers used.

Ceramic and metallic monolith structures have a geometrical surface area in the range 2.0-4.0m T support volume. This is much too low to adequately perform the catalytic conversion of the exhaust gas components. Therefore, these structures are coated with a thin layer of a mixture of inorganic oxides, some of which have a very high internal surface area. This mixture is called the washcoat (Fig. 36). 

A further simplification in the procedure to measure the catalytic activity is the use of a model gas reactor (Fig. 44). A small piece of catalyst is mounted in a reactor tube, the temperature of which can be externally adjusted. Most commonly, a monolithic core of diameter 2.54 cm and length 7.5 cm is used. The desired exhaust gas composition is simulated by mixing either pure gases or mixtures of the desired exhaust gas component with nitrogen. Such a model gas reactor test gives the highest possible flexibility, as each of the characteristic parameters of the exhaust gas, such as composition, temperature and space velocity, can be varied in a truly independent fashion. 

The technologies that lead to a quicker increase of the catalyst temperature will improve the catalytic performance for the conversion of all three exhaust gas components under consideration. However, some of the new legislation focuses on the... 

The exhaust gas of diesel engines has a complex composition as gaseous components are present together with liquid and even with solid components (Table 23). The solid exhaust gas components are denoted particulate matter, and defined as any matter that can be collected on a teflon-coated filter paper from diluted exhaust gas at a temperature below 325 K. Scanning and transmission electron microscopic pictures of such particulates are shown in Fig. 95. 

In addition to the exhaust gas components legislated for, the diesel oxidation catalyst also reduces the emissions of exhaust gas components such as aldehydes and polynuclear aromatic hydrocarbons, see Fig. Ill [70]. 

Figure 2. Change of the concentrations of the most significant exhaust gas components with time at 310°C during A,-cycling with A, = 1 0.05 and v = 0.3 Hz for catalysts Pd, Pd-Ce, Pd-Rh, Pd-Rh-Ce, Pt-Rh and Pt-Rh-Ce. The arrow indicates one rich half-cycle.

When the Irequency of X-cycling was increased to 1 Hz, concentrations of the exhaust gas components generally decreased markedly. The concentration-time profiles for catalysts Pd-Rh-Ce and Pt-Rh-Ce are depicted in Figure 3 as an example. Concentrations were very low and no... 

On-line analysis was perfonned for the hydrocarbons by a flame ioniziation detector, for CO, N2O and CO2 by NDIR-detectors, for NO, NO2 and NOx by a chemuluminescence detector and for O2 by a paramagnetic detector. Except for the O2 detector, all sample lines were heated to > 120°C to avoid condensation of the exhaust gas components. The amount of N2 formed by the reaction was calculated from the mass balance. A detailed list of the on-line analyzers used is given in Table 3. 

The emissions of the limited exhaust gas components are well below the applicable standards and are not presented here. 

Kley, D, H. Geiss and V. A. Mohnen (1994) Tropospheric ozone at elevated sites and precursor emissions in the United States and Europe. Atmospheric Environment 28, 149-158 Klingenberg, H. (1996) Automobile exhaust emission testing. Measurements of regulated and unregulateed exhaust gas components, exhaust emission tests. Springer-Verlag, Berlin,... 

Additional exhaust gas components Cleaned exhaust gas components... 

Chapter 3 Sanitary Products and Environmental Problems Table 15 Results from the analysis of exhaust gas components. 

---