New insights in the NOx reduction mechanism with H2 over Pt–Ba/γ-Al2O3 lean NOx trap catalysts under near-isothermal conditions

2006 ◽  
Vol 239 (1) ◽  
pp. 244-254 ◽  
Author(s):  
I NOVA ◽  
L LIETTI ◽  
L CASTOLDI ◽  
E TRONCONI ◽  
P FORZATTI
Keyword(s):  
Nox Reduction ◽  
Lean Nox Trap ◽  
Reduction Mechanism ◽  
Nox Trap ◽  
Isothermal Conditions ◽  
Lean Nox

Natural Gas Partial Oxidation and Reforming for Lean NOx Trap Catalysis Regeneration

2005 ◽  
Author(s):  
James E. Parks ◽  
Jim Tassitano
Keyword(s):  
Natural Gas ◽  
Nox Reduction ◽  
Department Of Energy ◽  
Regeneration Process ◽  
Cyclic Process ◽  
Lean Nox Trap ◽  
Nox Trap ◽  
Lean Combustion ◽  
Lean Nox ◽  
Environmental Goals

Program goals for the Advanced Reciprocating Engine Systems (ARES) program of the Department of Energy include efficiency and environmental goals. Lean-burn natural gas engines offer higher efficiency than engines that operate with Stoichiometric air-to-fuel mixtures; however, the excess oxygen in the exhaust of lean engines makes NOx reduction with catalytic aftertreatment difficult. Thus, advancing efficiency via lean combustion results in challenges to meet environmental goals. The lean NOx trap catalyst technology is capable of reducing NOx in lean exhaust and, thereby, enables the potential for lean combustion to meet both efficiency and environmental goals. During lean NOx trap catalysis, NOx in oxygen-rich exhaust is trapped on the catalyst by alkali or alkaline earth-based sorbate materials; then, upon exposure to oxygen-depleted exhaust, the NOx is released and reduced to nitrogen in a process called regeneration. The regeneration process renews the catalyst for more NOx trapping; the cyclic process repeats at periods on the order of a minute. Oxygen depletion during regeneration is accomplished by temporarily operating the catalyst at rich air-to-fuel ratios; traditionally, a variety of methods have been utilized to achieve rich conditions for the catalyst. In this presentation, research of a lean NOx trap on a lean natural gas engine will be presented. Natural gas from the engine supply was used to provide the reductant for the lean NOx trap regeneration process. The natural gas is injected into the exhaust system where oxidation and reforming catalysts partially oxidize and/or reform the natural gas into reductants suitable for lean NOx trap regeneration. Studies of the natural gas oxidation and reforming processes and their relation to NOx reduction performance will be presented.

Impact of Rh Oxidation State on NOx Reduction Performance of Multi-Component Lean NOx Trap (LNT) Catalyst

2016 ◽  
Vol 9 (3) ◽  
pp. 1615-1622 ◽  
Author(s):  
Junhui Li ◽  
Neal Currier ◽  
Aleksey Yezerets ◽  
Hai-Ying Chen ◽  
Howard Hess ◽  
...  
Keyword(s):  
Oxidation State ◽  
Nox Reduction ◽  
Lean Nox Trap ◽  
Nox Trap ◽  
Lean Nox

Lean NOx Trap Catalysis for NOx Reduction in Natural Gas Engine Applications

2004 ◽  
Author(s):  
James E. Parks ◽  
H. Douglas Ferguson ◽  
Aaron M. Williams ◽  
John M. E. Storey
Keyword(s):  
Power Generation ◽  
Carbon Monoxide ◽  
Natural Gas ◽  
Nox Reduction ◽  
Lean Nox Trap ◽  
Nox Trap ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Reciprocating Engines ◽  
Lean Nox

Reliable power generation and distribution is a critical infrastructure for the public and industry. Large-bore spark-ignited natural gas reciprocating engines are a reliable source of power generation. Lean operation enables efficient operation, and engines can conveniently be placed wherever natural gas resources are located. However, stricter emission regulations may limit the installation and use of more natural gas reciprocating engines if emissions cannot be reduced. Natural gas engine emissions of concern are generally methane, carbon monoxide, and oxides of nitrogen (NOx). Methane and carbon monoxide can be controlled by oxidation catalysts; however NOx emissions are difficult to control in lean exhaust conditions. One method of reducing NOx in lean exhaust conditions is lean NOx trap catalysis. Lean NOx trap technologies (also known as NOx adsorber catalysts, NOx storage and reduction catalysts, etc.) have demonstrated >90% NOx reduction for diesel reciprocating engines and natural gas turbines. In the work presented here, the feasibility of a lean NOx trap catalyst for lean burn natural gas reciprocating engines will be studied. Tests were conducted on a Cummins 8.3-liter engine on a dynamometer. The lean Nox trap catalyst was controlled in a valved exhaust system that utilized natural gas as the catalyst reductant. Oxidation and reformer catalysts were used to enhance utilization of methane for catalyst regeneration. The feasibility of this approach will be discussed based on the observed NOx reduction and associated fuel penalties.

scholarly journals NOx Reduction on Fully Formulated Lean NOx Trap Catalysts Subjected to Simulated Road Aging: Insights from Steady-State Experiments

2011 ◽  
Vol 32 (5) ◽  
pp. 736-745 ◽  
Author(s):  
Jin WANG ◽  
Yaying JI ◽  
Uschi GRAHAM ◽  
Caio CESAR SPINDOLA DE OLIVEIRA ◽  
Mark CROCKER
Keyword(s):  
Steady State ◽  
Nox Reduction ◽  
Lean Nox Trap ◽  
Nox Trap ◽  
Lean Nox

The effect of regeneration conditions on the selectivity of NOx reduction in a fully formulated lean NOx trap catalyst

2011 ◽  
Vol 175 (1) ◽  
pp. 83-92 ◽  
Author(s):  
Jin Wang ◽  
Yaying Ji ◽  
Vencon Easterling ◽  
Mark Crocker ◽  
Mark Dearth ◽  
...  
Keyword(s):  
Nox Reduction ◽  
Lean Nox Trap ◽  
Nox Trap ◽  
Lean Nox

Two-Level Nonlinear Model Predictive Control for Lean NOx Trap Regenerations

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Ming-Feng Hsieh ◽  
Junmin Wang ◽  
Marcello Canova
Keyword(s):  
Diesel Engine ◽  
Model Predictive Control ◽  
Predictive Control ◽  
Nonlinear Model ◽  
Nox Reduction ◽  
Nonlinear Model Predictive Control ◽  
Lean Nox Trap ◽  
Nox Trap ◽  
Profile Control ◽  
Lean Nox

This paper describes a two-level nonlinear model predictive control (NMPC) scheme for diesel engine lean NOx trap (LNT) regeneration control. Based on the physical insights into the LNT operational characteristics, a two-level NMPC architecture with the higher-level for the regeneration timing control and the lower-level for the regeneration air to fuel ratio profile control is proposed. A physically based and experimentally validated nonlinear LNT dynamic model is employed to construct the NMPC control algorithms. The control objective is to minimize the fuel penalty induced by LNT regenerations while keeping the tailpipe NOx emissions below the regulations. Based on the physical insights into the LNT system dynamics, different choices of cost function were examined in terms of the impacts on fuel penalty and tailpipe NOx slip amount. The designed control system was evaluated on an experimentally validated vehicle simulator, cX-Emissions, with a 1.9 l diesel engine model through the FTP75 driving cycle. Compared with a conventional LNT control strategy, 31.9% of regeneration fuel penalty reduction was observed during a single regeneration. For the entire cold-start FTP75 test cycle, a 28.1% of tailpipe NOx reduction and 40.9% of fuel penalty reduction were achieved.

The NOx Reduction by CO on a Pt−K/Al2O3 Lean NOx Trap Catalyst

2010 ◽  
Vol 115 (4) ◽  
pp. 1277-1286 ◽  
Author(s):  
L. Castoldi ◽  
L. Lietti ◽  
R. Bonzi ◽  
N. Artioli ◽  
P. Forzatti ◽  
...  
Keyword(s):  
Nox Reduction ◽  
Lean Nox Trap ◽  
Nox Trap ◽  
Lean Nox

Nanofiber Alumina Supported Lean NOx Trap: Improved Sulfur Tolerance and NOx Reduction

2013 ◽  
Vol 56 (1-8) ◽  
pp. 50-55 ◽  
Author(s):  
I. S. Pieta ◽  
M. García-Diéguez ◽  
M. A. Larrubia ◽  
L. J. Alemany ◽  
W. S. Epling
Keyword(s):  
Nox Reduction ◽  
Lean Nox Trap ◽  
Sulfur Tolerance ◽  
Nox Trap ◽  
Lean Nox
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