Automobile catalysts industry

The main uses of palladium [13] are in the electronics and electrical industries, in circuitry and in dental alloys. It finds many catalytic applications in industry, as well as in diffusion cells for the synthesis of hydrogen, and in automobile catalysts. Jewellery and three way auto-catalysts are the principal uses of platinum, which fulfils a wide range of roles in the chemical industry. 

It has to be noted that the adsorption of reactants is generally not uniform across the catalyst surface. Adsorption, and therefore catalysis, takes place mainly at certain favorable locations on a surface called active sites. In environmental chemistry, catalysts are essential for breaking down pollutants such as automobile and industrial exhausts. 

Figure 12. Velocity distribution in an industrially housed automobile catalyst [14].

Figure 12 shows the velocity distribution in front of the monolith inlet for an industrially housed automobile catalyst [14]. Since the flow cannot follow the sudden widening of the inlet funnel, one third of the total cross section is traversed at a velocity that is roughly three times the mean velocity. It can be estimated that, with uniform flow through the catalyst, half the catalyst volume would be sufficient for the same mean conver-... 

The world s supply of rhodium is in approximate balance with demand with erratic releases onto the world market from Russia being counterbalanced by national and industrial stockpiles. These fluctuations in availability are reflected in the spot price, which fell from US 64 at the millennium to US 17g by 2001. The current price in 2004 is US 26 g. Of the 2002 world production of 19.0 tonnes and recovered scrap from automobile catalysts of 3.1 tonnes, over 80% was used as rhodium alloy catalysts for automobile emission reduction. The rhodium component is vital in controlling NO emissions and looks set to increase in order to meet higher emission control standards. 

Platinum group elements (PGE) are used as catalysts in a variety of industrial, chemical and pharmaceutical applications, such as in the production of pesticides and dye stuffs and in the processing of polymers. These rare noble metals, notably platinum (Pt), rhodium (Rh) and palladium (Pd), are also used as catalysts in automobile catalytic converters to reduce the emission of carbon monoxide (CO), nitrogen oxides (NOJ and hydrocarbons (HC) in exhaust fumes. This application, in fact, accounts for the largest consumption of the global supply of these metals on a per weight basis. In 2008, for instance, catalytic converter producers consumed a total of 52, 47 and 86% of the world s Pt, Pd and Rh, respectively (Matthey 2008). Pd use by the catalyst industry increased by a factor of six from 1993 to 2008 (Matthey 1996, 2008). 

Environmental catalysts (industrial and automobile environmental catalysts)... 

Automotive Catalytic Converter Catalysts. California environmental legislation in the early 1960s stimulated the development of automobile engines with reduced emissions by the mid-1960s, led to enactment of the Federal Clean Air Act of 1970, and resulted in a new industry, the design and manufacture of the automotive catalytic converter (50). Between 1974 and 1989, exhaust hydrocarbons were reduced by 87% and nitrogen oxides by 24%. 

Beginning with the 1975 U.S. automobiles, catalytic converters were added to nearly all models to meet the more restrictive emission standards. Since the lead used in gasoline is a poison to the catalyst used in the converter, a scheduled introduction of unleaded gasoline was also required. The U.S. petroleum industry simultaneously introduced unleaded gasoline into the marketplace. 

In 1996, consumption in the western world was 14.2 tonnes of rhodium and 3.8 tonnes of iridium. Unquestionably the main uses of rhodium (over 90%) are now catalytic, e.g. for the control of exhaust emissions in the car (automobile) industry and, in the form of phosphine complexes, in hydrogenation and hydroformylation reactions where it is frequently more efficient than the more commonly used cobalt catalysts. Iridium is used in the coating of anodes in chloralkali plant and as a catalyst in the production of acetic acid. It also finds small-scale applications in specialist hard alloys. 

The polymer field is versatile and fast growing, and many new polymers are continually being produced or improved. The basic chemistry principles involved in polymer synthesis have not changed much since the beginning of polymer production. Major changes in the last 70 years have occurred in the catalyst field and in process development. These improvements have a great impact on the economy. In the elastomer field, for example, improvements influenced the automobile industry and also related fields such as mechanical goods and wire and cable insulation. 

For the U.S., the new EPA rules will limit sulfur in gasoline to 30 ppm, phased between 2004 and 2006. The automobile industry has made a strong case for lower sulfur because of its effect on the catalytic converter. The converter has the same catalyst as the refinery reformer and it is poisoned just as easily by sulfur. 

The main use of rhodium is with platinum in catalysts for oxidation of automobile exhaust emissions. In the chemical industry, it is used in catalysts for the manufacture of ethanoic acid, in hydroformylation of alkenes and the synthesis of nitric acid from ammonia. Many applications of iridium rely on... 

A catalytic oxidation system may cost 150 per car, but the catalyst cost is estimated to be 30, less than 1% of the cost of an automobile (2). In a few years, the gross sale of automotive catalysts in dollars may exceed the combined sale of catalysts to the chemical and petroleum industries (3). On the other hand, if the emission laws are relaxed or if the automotive engineers succeed in developing a more economical and reliable non-catalytic solution to emission control, automotive catalysis may turn out to be a short boom. Automotive catalysis is still in its infancy, with tremendous potential for improvement. The innovations of catalytic scientists and engineers in the future will determine whether catalysis is the long term solution to automotive emissions. 

The catalyst companies were encouraged to resume their research activities in automotive catalysis in the late 1960 s as further tightening of automotive emissions standards became imminent, and it appeared that mere engine modifications might be inadequate to meet the new standards. A systems approach was first used upon the formation of the Inter-Industry Emission Control Program by the Ford Motor Company and the Mobil Oil Corporation in 1967, which was joined by a number of oil companies in the U.S. and a number of automobile companies in Italy, Japan, and Western Germany. 

We have included in this volume two chapters specifically related to society s kinetic system. We have asked James Wei of the University of Delaware, recent Chairman of the consultant panel on Catalyst Systems for the National Academy of Sciences Committee on Motor Vehicle Emissions, to illustrate key problems and bridges between the catalytic science and the practical objectives of minimizing automobile exhaust emissions. We have also asked for a portrayal of the hard economic facts that constrain and guide what properties in a catalyst are useful to the catalytic practitioner. For this we have turned to Duncan S. Davies, General Manager of Research and Development, and John Dewing, Research Specialist in Heterogeneous Catalysts, both from Imperial Chemical Industries Limited. 

By far the most important use of the platinum metals is for catalysis. The largest single use is in automobile catalytic converters. Platinum is the principal catalyst, but catalytic converters also contain rhodium and palladium. These elements also catalyze a wide variety of reactions in the chemical and petroleum industry. For example, platinum metal is the catalyst for ammonia oxidation in the production of nitric acid, as described in Pt gauze, 1200 K... 

While the discovery of the catalytic properties of zeolites was driven by the desire to improve industrial prcKessing, the development of emission control catalysts was necessitated by governmental fiat. The first requirement was for 90+% removal of CO and of hydrocarbons, a goal which could not be met by oxidation with base metal oxides. To achieve the required spedfications during automobile operations, it was necessary to develop supported platinum catalysts. Originally the support was alumina in pellet form. Later platinum on cordierite was used in honeycomb form, containing 200-400 square channels per square inch. 

Supported bimetallic catalysts find many industrial applications. Examples include Pt and Rh in automobile exhaust conversion catalysts and Pt and Re (or Pt and Sn or Pt and Ir) in naphtha reforming catalysts. 

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