Catalyst additives converter, automobiles

The compound cerium oxide (either Ce Oj or CeO ) is used to coat the inside of ovens because it was discovered that food cannot stick to oven walls that are coated with cerium oxide. Cerium compounds are used as electrodes in high-intensity lamps and film projectors used by the motion picture industry. Cerium is also used in the manufacturing and polishing of high-refraction lenses for cameras and telescopes and in the manufacture of incandescent lantern mantles. It additionally acts as a chemical reagent, a misch metal, and a chemical catalyst. Cerium halides are an important component of the textile and photographic industries, as an additive to other metals, and in automobile catalytic converters. Cerium is also used as an alloy to make special steel for jet engines, solid-state instruments, and rocket propellants. 

The promotion ability of cerium is attributed to its capability to form crystalline oxides with lattice defects, which may act as active sites [25]. In addition, the presence of cerium oxide in the catalyst improves its thermal stability and mechanical resistance [26]. Cerium is the most frequent additive used for preparation of the automobile converter catalyst that transforms carbon monoxide, hydrocarbons and nitrogen oxides [27,28]. 

An example of a catalyst that is slowly destroyed in the course of its catalytic action is the catalytic converter in new automobiles. The Pt catalyst accelerates the conversion of CO to CO2. At the same time it also aids in the formation of SO3 and NO2, products which, at elevated temperatures, will combine with the Pt. In addition it is poisoned by accumulation of carbon on the surface. 

The US Clean Air Act (CAA) of 1970 required that automobile exhaust emissions be regulated to meet new environmental standards. From 1975 all new models were to be fitted with catalytic combustion converters to reduce levels of carbon monoxide and unbumt hydrocarbons in the exhaust. This led to the phase-out of lead additives in gasoline between 1973 and 1996. To compensate for the loss of octane rating of the gasoline more reformate and alkylate needed to be added. Octane catalysts were also developed for FCC units and the aromat-... 

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