Stoichiometric gasoline engines

In a general manner, diesel engines, jet engines, and domestic or industrial burners operate with lean mixtures and their performance is relatively insensitive to the equivalence ratio. On the other hand, gasoline engines require a fuel-air ratio close to the stoichiometric. Indeed, a too-rich mixture leads to an excessive exhaust pollution from CO emissions and unburned hydrocarbons whereas a too-lean mixture produces unstable combustion (reduced driveability and misfiring). 

Natural gas engines can use lean-burn or stoichiometric combustion. Lean-burn combustion is similar to that which occurs in diesel engines, while stoichiometric combustion is more similar to the combustion in a gasoline engine. 

The catalyst was evaluated under simulated gasoline engine emissions for oxidising (0.9% O2) and reducing (0.6% O2) conditions close to stoichiometric. Under oxidising conditions, the catalyst displayed a CO T50 of 348-358 K, an HC T50 of 513 K and as expected no NO reduction. The CO T50 remained unaffected under reducing conditions, whereas the HC T50 increased to 583 K. Complete conversion of NOj, occurred at approximately 603 K, with a T50 of 573 K under reducing conditions. Selectivity for reduction to N2 over N2O is not known. 

The operation of a spark ignition gasoline engine above the stoichiometric point reduces the fuel consumption and therefore the CO2 emission of the engine. At the same time, the engine-out emissions of CO, NO t and up to some defined A/F-ratio,... 

There is currently a great interest in improving automobile fuel economy and to reduce emissions of carbon dioxide into the atmosphere. One step in this direction is to use a technique where a gasoline engine is operated at lean-bum conditions. Using this concept it is possible to improve fuel economy significantly [1,2] compared to the normal stoichiometric operation. A setback with lean-bum technology is that Ae common three-way catalyst is... 

Carbon monoxide is a product of incomplete combustion of carbonaceous fuels. It is most notable as an emission from gasoline engines, which run very close to a stoichiometric mixtirre of hydrocarbon fuel and air, compared to the diesel, which rans with substantial excess air and emits far less carbon monoxide per kilometer driven. Carbon monoxide concentrations were a matter of concern in developed countries prior to the adoption of auto-... 

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