Microkinetic modeling for hydrocarbon (HC)-based selective catalytic reduction (SCR) of NOx on a silver-based catalyst

Mhadeshwar, Ashish B.; Winkler, Benjamin; Eiteneer, Boris; Hâncu, Dan

doi:10.1016/j.apcatb.2009.02.012

Cited by 29 publications

(23 citation statements)

References 34 publications

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“…19,[28][29][30] However, these models all describe hydrocarbon SCR (HCASCR). The objective of this study is to develop a simple global kinetic model for H 2 -assisted NH 3 -SCR over an Ag/Al 2 O 3 catalyst, which can be used for the dosing strategy of NH 3 and H 2 .…”

Section: Introductionmentioning

confidence: 99%

A kinetic model of the hydrogen assisted selective catalytic reduction of NO with ammonia over Ag/Al₂O₃

et al. 2013

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A global kinetic model which describes H 2 -assisted NH 3 -SCR over an Ag/Al 2 O 3 monolith catalyst has been developed. The intention is that the model can be applied for dosing NH 3 and H 2 to an Ag/Al 2 O 3 catalyst in a real automotive application as well as contribute to an increased understanding of the reaction mechanism for NH 3 -SCR. Therefore, the model needs to be simple and accurately predict the conversion of NO x . The reduction of NO is described by a global reaction, with a molar stoichiometry between NO, NH 3 and H 2 of 1:1:2. Further reactions included in the model are the oxidation of NH 3 to N 2 and NO, oxidation of H 2 , and the adsorption and desorption of NH 3 . The model was fitted to the results of an NH 3 -TPD experiment, an NH 3 oxidation experiment, and a series of H 2 -assisted NH 3 -SCR steady-state experiments. The model predicts the conversion of NO x well even during transient experiments. V C 2013 American Institute of Chemical Engineers AIChE J, 59: [4325][4326][4327][4328][4329][4330][4331][4332][4333] 2013

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Section: Introductionmentioning

confidence: 99%

A kinetic model of the hydrogen assisted selective catalytic reduction of NO with ammonia over Ag/Al₂O₃

et al. 2013

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“…Numerous efforts have been made to replace ammonia with hydrocarbons in SCR processes, especially in an oxygen-rich environment [8][9][10]. Many types of hydrocarbons have been tested including methane, ethane, ethylene, propane, propylene, octane, benzene, acetone, cyclohexane, diesel oil, methanol, and ethanol.…”

Section: Introductionmentioning

confidence: 99%

Catalytic process for decolorizing yellow plume

Yang

Chun

et al. 2011

Korean J. Chem. Eng.

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Yellow-colored exhaust gas streams from internal engines or gas turbines, frequently referred to as "yellow plume," contain nitrogen dioxide (NO 2 ) at concentrations as low as 15 ppm. The process developed in this work for decolorizing the yellow plume is based on reduction of NO 2 to NO utilizing a combination of a Pt catalyst and a reducing agent. A stoichiometric excess of carbon monoxide, diesel oil, methanol or ethanol were used as reducing agents. Depending on the type of the reductant, the active temperature window of NO 2 reduction was varied with methanol and CO being active at lower temperatures and ethanol and diesel oil at higher temperatures. By changing the Pt loading of the catalysts the active temperature window of NO 2 reduction was also changed, higher loading Pt catalysts being active at lower temperatures. This scheme of NO 2 reduction process was verified in a pilot-scale test with the real exhaust gas from the gas turbine power plant, showing 96% of NO 2 reduction at the stack temperatures of 102-123 o C and at space velocities of 28,000-95,000 h −1 with inherent CO in the exhaust gas as the reducing agent.

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“…As shown in Figure 3a, n-heptane decomposition produces such aldehydes. It is thought that the HC-SCR reaction proceeds with the decomposition reactions of hydrocarbon [15,34]. In order for n-heptane to serve as a reducing agent for NOx removal, it must first be decomposed through a series of complicated reaction steps.…”

Section: Effect Of N-heptane Decomposition Products On the Catalytic mentioning

confidence: 99%

“…Since aldehydes are already in such a decomposed state, it is natural that NOx reduction performance should increase when an aldehyde is used as a reducing agent. It has been reported that the reactions taking place in HC-SCR involve the production of ammonia (NH3) via the formation of oxygenated hydrocarbons (CxHyOz) [34][35][36]. For example, alkanes (RH) produce aldehydes like CH3CHO through sequential oxidation reactions via alkoxy (RO) or alkyl (R) that are unstable intermediates, and aldehydes are eventually converted into NH3 via isocyanate intermediate (NCO) on the catalyst surface [34].…”

Section: Effect Of N-heptane Decomposition Products On the Catalytic mentioning

confidence: 99%

Consideration of the Role of Plasma in a Plasma-Coupled Selective Catalytic Reduction of Nitrogen Oxides with a Hydrocarbon Reducing Agent

Lee

Kang

et al. 2017

Catalysts

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Abstract:The purpose of this study is to explain how plasma improves the performance of selective catalytic reduction (SCR) of nitrogen oxides (NO x ) with a hydrocarbon reducing agent. In the plasma-coupled SCR process, NO x reduction was performed with n-heptane as a reducing agent over Ag/γ-Al 2 O 3 as a catalyst. We found that the plasma decomposes n-heptane into several oxygen-containing products such as acetaldehyde, propionaldehyde and butyraldehyde, which are more reactive than the parent molecule n-heptane in the SCR process. Separate sets of experiments using acetaldehyde, propionaldehyde and butyraldehyde, one by one, as a reductant in the absence of plasma, have clearly shown that the presence of these partially oxidized compounds greatly enhanced the NO x conversion. The higher the discharge voltage, the more the amounts of such partially oxidized products. The oxidative species produced by the plasma easily converted NO into NO 2 , but the increase of the NO 2 fraction was found to decrease the NO x conversion. Consequently, it can be concluded that the main role of plasma in the SCR process is to produce partially oxidized compounds (aldehydes), having better reducing power. The catalyst-alone NO x removal efficiency with n-heptane at 250 • C was measured to be less than 8%, but it increased to 99% in the presence of acetaldehyde at the same temperature. The NO x removal efficiency with the aldehyde reducing agent was higher as the number of carbons in the aldehyde was more; for example, the NO x removal efficiencies at 200 • C with butyraldehyde, propionaldehyde and acetaldehyde were measured to be 83.5%, 58.0% and 61.5%, respectively, which were far above the value (3%) obtained with n-heptane.

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Microkinetic modeling for hydrocarbon (HC)-based selective catalytic reduction (SCR) of NOx on a silver-based catalyst

Cited by 29 publications

References 34 publications

A kinetic model of the hydrogen assisted selective catalytic reduction of NO with ammonia over Ag/Al₂O₃

A kinetic model of the hydrogen assisted selective catalytic reduction of NO with ammonia over Ag/Al₂O₃

Catalytic process for decolorizing yellow plume

Consideration of the Role of Plasma in a Plasma-Coupled Selective Catalytic Reduction of Nitrogen Oxides with a Hydrocarbon Reducing Agent

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Microkinetic modeling for hydrocarbon (HC)-based selective catalytic reduction (SCR) of NOx on a silver-based catalyst

Cited by 29 publications

References 34 publications

A kinetic model of the hydrogen assisted selective catalytic reduction of NO with ammonia over Ag/Al2O3

A kinetic model of the hydrogen assisted selective catalytic reduction of NO with ammonia over Ag/Al2O3

Catalytic process for decolorizing yellow plume

Consideration of the Role of Plasma in a Plasma-Coupled Selective Catalytic Reduction of Nitrogen Oxides with a Hydrocarbon Reducing Agent

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A kinetic model of the hydrogen assisted selective catalytic reduction of NO with ammonia over Ag/Al₂O₃

A kinetic model of the hydrogen assisted selective catalytic reduction of NO with ammonia over Ag/Al₂O₃