Development of an Ammonia Reduction Aftertreatment Systems for Stoichiometric Natural Gas Engines

Abstract

Development of an Ammonia Reduction After-treatment Systems for Stoichiometric Natural Gas Engines Saroj Pradhan Three-way catalyst (TWC) equipped stoichiometric natural gas vehicles have proven to be an effective alternative fuel strategy that shows significant low NOx emissions characteristics. However, recent studies have shown the TWC activity to contribute to elevated levels of tailpipe ammonia (NH3) emissions. Although a non-regulated pollutant, ammonia is a potent precursor to ambient secondary PM formation. Ammonia is an inevitable byproduct of fuel rich operation that results in lowest NOx slip through the TWC after-treatment system. The main objective of the study is to develop a passive Ammonia Reduction Catalyst (passive-ARC) based NH3 reduction strategy that results in an overall reduction of ammonia as well as NOx emissions. The study investigated the characteristics of Fe-based and Cu-based zeolites SCR catalysts in storage and desorption of ammonia at high exhaust temperature conditions, that are typical of stoichiometric natural gas engines. Continuous measurements of NOx and NH3 before and after the SCR systems were conducted using a Fourier Transform Infrared Spectrometry (FTIR) gas analyzer. Results of the investigation showed that both, the

Ammonia Emissions in SI Engines Fueled with LPG

“…570 • C. This means that one of the reactions responsible for the NH 3 formation (i.e., (1) or ( 2)) is accelerated. It is claimed [3] that this is an effect of water gas shift reaction (reaction (3)). At higher temperatures, this reaction slows down and the hydrogen needed for NH 3 formation is produced as a result of hydrocarbons steam reforming (reaction (4)).…”

“…It was a V-type engine with a displacement of 7.2 dm 3 , equipped with two TWCs. The diameter of the TWC's metal substrate was 148 mm, catalyst body volume 4.22 dm 3 , cell density 400 cpsi, and precious metal charge 70 g/ft 3 The used experimental equipment allowed to ensure the accuracy of emission measurements of 2%.…”

“…Ammonia, even at low concentrations, has an unpleasant odor when released into the air but most notably harms vegetation, particularly at high concentrations. In water bodies, ammonia causes more serious harm due to the toxicity to organisms living in water [3]. Regulation No.…”

“…CO is a natural component of exhaust gases and has higher concentrations when the air-fuel mixture is rich. H 2 can be obtained in the exhaust gas in two ways-during the combustion stroke, where, under high pressures and temperature, the hydrogen contained in the fuel is released or by means one of the below reactions: the water gas shift (3) or the steam reforming (4).…”