Clean exhaust emission

The products manufactured are predominantiy paraffinic, free from sulfur, nitrogen, and other impurities, and have excellent combustion properties. The very high cetane number and smoke point indicate clean-burning hydrocarbon Hquids having reduced harmful exhaust emissions. SMDS has also been proposed to produce chemical intermediates, paraffinic solvents, and extra high viscosity index (XHVI) lubeoils (see Lubrication and lubricants) (44). 

Since that time, a variety of alternatives to refined petroleum products have been evaluated and used as fuels for internal combustion engines. Reasons for considering synthetic and alternative fuels stem from two primary motivating factors the need to ensure an adequate supply of low-cost fuel, and the desire to use fuel that bums completely and cleanly without undesirable exhaust emissions. 

Monolith reactor This type of reactor is used extensively for the abatement of automobiles exhaust emissions. The gas flows continuously through the reactor, whereas the catalyst is a continuous phase consisting of a ceramic support and the active phase, which is dispersed onto the support. The support is structured in many channels and shapes that achieve large catalytic surface at small volume. A typical application of monolith reactors is the exhaust gas cleaning. 

Exhaust emission standards since the 1981 model year vehicles have required the use of three-way catalysts, either alone or in combination with an oxidation catalyst. Three-way catalysts are designed to operate in a very narrow range about the stoichiometric air/fuel ratio. In this range the HC and CO are subject to oxidation and the NO, compounds undergo reduction. The downstream oxidation catalyst in a dual bed system is generally used as a "clean-up catalyst lo further control HC and CO emissions. The most common catalytic combination in three-way uses is platinum/rhodium. Current production applications use these elements in a relatively rich proportion of 5 1 lo 10 1. whereas the respective mine ratio is about 19 1. 

Nishikawa, S. Hill, L. Kihara, N. Clean up in Engine R D Your Guide to Lowering Exhaust Emissions, Engine Technol. Intern. 2000, 4, 112— 114. http //www.emd.horiba.com/engmeas/techpdf/ cleanup engine corr.pdf... 

The implementation of this exhaust clean up device on automobiles was actually forced by the Clean Air Act amendment of 1970 in the United States. After ten years of usage, nearly 150 million catalytic converters have been produced. It is broadly accepted as the most practical way for auto makers to comply with exhaust emissions regulations. 

Catalytic incineration (complete air oxidation) for the purification of gas streams is now quite commonly used in many applications (1-7), being preferred in these over thermal (non-catalytic) incineration and adsorption methods. It can offer advantages over thermal incineration in terms of costs, size, efficiency of destruction, and minimization of thermal NOx by-product formation. The catalytic incineration systems are now commonly employed in such applications as exhaust emission purification from a variety of industrial processes (including manufacture of organic chemicals and polymers) and air-stripping catalytic processes used to clean contaminated water or soil. 

In the USA, the main interest in FCVs is centred on California. This activity is driven by the State s strict environmental laws on the control of vehicle exhaust emissions, as well as by a desire to be independent of petroleum imports. Hydrogen is seen as both a clean fuel and one that can be multi-sourced... 

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