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The effects of propylene (C₃H₆) and dodecane (n-C₁₂H₂₆) exposure on the NH₃-based selective catalytic reduction (SCR) performance of two Cu-exchanged zeolite catalysts were investigated. The first sample was a model Cu/beta zeolite sample and the second a state-of-the-art Cu/zeolite sample, with the zeolite material characterized by relatively small pores. Overall, the state-of-the-art sample performed better than the model sample, in terms of hydrocarbon inhibition (which was reduced) and N₂O formation (less formed). The state-of-the-art sample was completely unaffected by dodecane at temperatures lower than 300°C, and only slightly inhibited (less than 5% conversion loss), for standard SCR, by C₃H₆. There was no evidence of coke formation on this catalyst with C₃H₆ exposure. The model sample was more significantly affected by hydrocarbon exposure. With C₃H₆, inhibition is associated with its partial oxidation intermediates adsorbed on the catalyst surface.

The performance of a commercial Cu-zeolite SCR catalyst after differing degrees of hydrothermal aging (aged for 72 hours at 500, 700 and 800°C with 10% moisture balanced with air) was studied by spatially resolving different key reactions using gas-phase FTIR measurements. Gases were sampled along a channel at different positions and analyzed using FTIR, which overcomes the interference of water and nitrogen on ammonia concentration detection encountered in standard mass spectrometer-based spatial resolution measurements. The NO:NO₂ concentration ratio was changed so that the standard (NO:NO₂ = 1:0), fast (NO:NO₂ = 1:1) and NO₂ (NO:NO₂ = 0:1) SCR reactions could be investigated as a function of the catalyst's hydrothermal aging extent. In addition, the effects of hydrothermal aging on the activity of NH₃ and NO oxidation were also investigated. Hydrothermal aging had little effect on NO oxidation activity.

The low-temperature performance characteristics of a commercial lean NOX trap catalyst were evaluated using infra-red thermography (IRT) before and after a high-temperature aging step. Reaction tests included propylene oxidation, oxygen storage capacity measurements, and simulated cycling conditions for NOX reduction, using H₂ as the reductant during the regeneration step of the cycle. Testing with and without NO in the lean phase showed thermal differences between the reductant used in reducing the stored oxygen and that for nitrate decomposition and reduction. IRT clearly demonstrated where NOX trapping and regeneration were occurring spatially as a function of regeneration conditions, with variables including hydrogen content of the regeneration phase and lean- and rich-phase cycle times.

The performance characteristics of a commercial lean-NOX trap catalyst were evaluated between 200 and 500°C, using H2, CO, and a mixture of both H2 and CO as reductants before and after different high-temperature aging steps, from 600 to 750°C. Tests included NOX reduction efficiency during cycling, NOX storage capacity (NSC), oxygen storage capacity (OSC), and water-gas-shift (WGS) and NO oxidation reaction extents. The WGS reaction extent at 200 and 300°C was negatively affected by thermal degradation, but at 400 and 500°C no significant change was observed. Changes in the extent of NO oxidation did not show a consistent trend as a function of thermal degradation. The total NSC was tested at 200, 350 and 500°C. Little change was observed at 500°C with thermal degradation but a steady decrease was observed at 350°C as the thermal degradation temperature was increased.

Automobile fires are a serious concern to manufacturers and consumers. However, understanding how the fires begin, in the confines of the engine compartment, is a difficult task. One known cause of fires is hot surface ignition (HSI) arising when engine fluids contact hot surfaces in the engine compartment or the exhaust train. In this study, the ignition of automotive gasoline on four hot surfaces: stainless and carbon steels from the heat shields, stainless steel from the exhaust manifold and cast iron cut from an intake manifold, was examined in a well-controlled, model study. Infra-red thermography and thermocouples were used to monitor surface temperatures prior to, during and after the fluid impacted the surface. This allowed evaluation and comparison of temperature evolution during fluid impact and the ignition event, resulting in an improved mechanistic understanding of the fluid/hot surface interaction.

NOx absorber catalysts can obtain NOx reduction efficiencies greater than 90% in lean exhaust. Since upcoming U.S. EPA emission regulations for diesel engines will require high NOx reduction efficiencies, NOx absorber catalysts are under consideration for use in compliance. However, durability issues in diesel engine exhaust need to be addressed. Specifically, sulfur is a known masking agent in NOx absorber catalysis. One method of controlling sulfur masking is by removal of sulfur compounds from the catalyst in a reducing environment; this process is referred to as desulfation and typically occurs at elevated catalyst temperatures. Over the catalyst lifetime, many (100-1,000) sulfur loading and desulfation cycles may occur, and recovery during desulfation must be sufficient to meet the regulation. Here the effect of multiple repetitive sulfur loading and desulfation cycles on catalyst performance will be studied.

A two-chamber catalyst system for the aftertreatment of No. 2 Diesel exhaust is demonstrated. NOx conversion efficiencies greater than 90% were obtained over a broad range of operating temperatures and NOx levels. The system incorporates a catalyst (SCONOx™) for the removal of CO, hydrocarbons, and NOx from the exhaust stream and a sulfur catalyst (SCOSOx™) for the protection of the NOx catalyst from sulfur poisoning. Both catalysts are of sorbate or “trap” type. No. 2 Diesel and hydrogen were used as reductants. Tests of the catalysts were performed with various loads, temperatures, and NOx levels. A light-duty diesel engine with no particulate control was used for the tests. All tests were conducted using No. 2 Diesel fuel. NOx conversion decay is compared with and without sulfur catalyst protection.