Emissions catalytic

Dalla Betta, Ralph A., Nicholas, S.G., Weakley, C.K., Lundberg, K., Caron, T.J., Chamberlain, J., and Greeb, K., Field Test of a 1.5 MW Industrial Gas Turbine with a Low Emissions Catalytic Combustion System, ASME 99-GT-295. 

Transportation - production of gasoline and diesel from petroleum, fuel additives for greater efficiency and reduced emissions, catalytic converters, plastics to reduce vehicle weight and improve energy efficiency. 

Triboemission time is extremely short while after-emission time is much longer. The enhanced surface activity caused by rubbing processes produces exoelectrons emission, catalytic and structural factors, increased surface temperature, and pressure (Rowe and Murphy, 1974). 

Two different technologies seem to be the most promising alternatives to reduce gaseous PAH emissions catalytic PAH destruction [6, 7] and PAH adsorption on carbonaceous materials [8, 9]. Historically, carbonaceous materials have been used for the removal of vapor phase organic compounds from about 100 ppmv to 10,000 ppmv concentrations in industrial waste gas streams [10]. Recently, it has been shown that dioxins, furans and PAH, at ppbv or lower coneentrations, can be effectively removed from waste incinerator combustion gases by using carbon injection or carbon bed technology [11]. 

The three-way catalyst works in a narrow range of air-fuel ratio, approximately the stoichiometric ratio. Hence, it is not effective with lean-burn engines that offer higher fuel efficiency at the expense of higher NO emissions. Catalytic systems under development for post-2004 U.S. NOx emission regulations are based on NOx traps, which adsorb NOxas nitrates. These emission control systems are active. They require peri-... 

As a preventive solution to the problem of NOx emissions, catalytic combustion has come to the forefront during the last two decades. The focus of major interest here is its application in gas turbines for power generation and for transportation by road, water or air. Any catalyst for catalytic combustion, however, has to face extreme demands above 1000°C in the presence of oxygen and steam, in uninterrupted operation for at least one year also, resistance to impurities or poisons in the fuel and to severe thermal and mechanical shocks. Promising developments in catalytic supports, washcoats and active materials are reviewed briefly. 

Alavandi SK, Etemad S, Baird BD Low single digit NOx emissions catalytic combustor for advanced hydrogen turbines for clean coal power systems, ASME GT2012-68128. 

However, such a level can still be considered too high for vehicles having 3-way catalytic converters. In fact, results observed in the United States (Benson et al., 1991) and given in Figure 5.20 show that exhaust pollutant emissions, carbon monoxide, hydrocarbons and nitrogen oxides, increase from 10 to 15% when the sulfur level passes from 50 ppm to about 450 ppm. This is explained by an inhibiting action of sulfur on the catalyst though... 

Influence of the sulfur content in diesel fuel on particulate emissions as a, function of the catalytic converter inlet temperature. 

The implementation of very effective devices on vehicles such as catalytic converters makes extremely low exhaust emissions possible as long as the temperatures are sufficient to initiate and carry out the catalytic reactions however, there are numerous operating conditions such as cold starting and... 

Control of NO emissions from nitric acid and nitration operations is usually achieved by NO2 reduction to N2 and water using natural gas in a catalytic decomposer (123—126) (see Exhaust control, industrial). NO from nitric acid/nitration operations is also controlled by absorption in water to regenerate nitric acid. Modeling of such absorbers and the complexities of the NO —HNO —H2O system have been discussed (127). Other novel control methods have also been investigated (128—129). Vehicular emission control is treated elsewhere (see Exhaust control, automotive). 

Although the naturally occurring concentration of ozone at the earth s surface is low, the distribution has been altered by the emission of pollutants, primarily by automobiles but also from industrial sources which lead to the formation of ozone. The strategy for controlling ambient ozone concentrations arising from automobile exhaust emissions is based on the control of hydrocarbons, CO, and NO via catalytic converters. As a result, peak ozone levels in Los Angeles, for instance, have decreased from 0.58 ppm in 1970 to 0.33 ppm in 1990, despite a 66% increase in the number of vehicles. 

PGM catalyst technology can also be appHed to the control of emissions from stationary internal combustion engines and gas turbines. Catalysts have been designed to treat carbon monoxide, unbumed hydrocarbons, and nitrogen oxides in the exhaust, which arise as a result of incomplete combustion. To reduce or prevent the formation of NO in the first place, catalytic combustion technology based on platinum or palladium has been developed, which is particularly suitable for appHcation in gas turbines. Environmental legislation enacted in many parts of the world has promoted, and is expected to continue to promote, the use of PGMs in these appHcations. 

The additional sulfur for polysulfide pulping can upset the sodium—sulfur balance in the kraft recovery cycle and increase sulfur emission problems. In the MOXY (Mead Corp.) process, polysulfide is formed from kraft white Hquor by catalytic oxidation of sodium sulfide in the white Hquor using air. 

Reduced Emissions and Waste Minimization. Reducing harmful emissions and minimizing wastes within a process by inclusion of additional reaction and separation steps and catalyst modification may be substantially better than end-of-pipe cleanup or even simply improving maintenance, housekeeping, and process control practices. SO2 and NO reduction to their elemental products in fluid catalytic cracking units exemplifies the use of such a strategy (11). 

The air stream exiting a stripper may requite some type of emissions control, depending on local and regulatory requirements. Carbon adsorption is often used catalytic oxidation is another option. 

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%. 

In principle, the catalytic converter is a fixed-bed reactor operating at 500—620°C to which is fed 200—3500 Hters per minute of auto engine exhaust containing relatively low concentrations of hydrocarbons, carbon monoxide, and nitrogen oxides that must be reduced significantly. Because the auto emission catalyst must operate in an environment with profound diffusion or mass-transfer limitations (51), it is apparent that only a small fraction of the catalyst s surface area can be used and that a system with the highest possible surface area is required. 

Another potential solution is the use of catalytic combustors, which produce extremely low levels of emissions by the use of combustion catalysts such as platinum. The main disadvantage of catalytic combustors, however, is thek high cost. 

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