Effect of Reductive Regeneration Conditions on Reactivity and Stability of a Pd-Based Oxidation Catalyst for Lean-Burn Natural Gas Applications

2016 ◽  
Author(s):  
Yuanzhou Xi ◽  
Nathan Ottinger ◽  
Z. Gerald Liu
Keyword(s):  
Natural Gas ◽  
Oxidation Catalyst ◽  
Lean Burn

Poison Build-up and Performance Degradation of an Oxidation Catalyst in 2-Stroke Natural Gas Engine Exhaust

2017 ◽  
Author(s):  
Marc E. Baumgardner ◽  
Daniel B. Olsen
Keyword(s):  
Natural Gas ◽  
Catalyst Deactivation ◽  
Catalyst Surface ◽  
Oxidation Catalyst ◽  
Lean Burn ◽  
Gas Field ◽  
Natural Gas Engines ◽  
Engine Testing ◽  
And Performance ◽  
Carry Over

Due to current and future exhaust emissions regulations, oxidation catalysts are increasingly being added to the exhaust streams of large-bore, 2-stroke, natural gas engines. Such catalysts have been found to have a limited operational lifetime, primarily due to chemical (i.e. catalyst poisoning) and mechanical fouling resulting from the carry-over of lubrication oil from the cylinders. It is critical for users and catalyst developers to understand the nature and rate of catalyst deactivation under these circumstances. This study examines the degradation of an exhaust oxidation catalyst on a large-bore, 2-stroke, lean-burn, natural gas field engine over the course of 2 years. Specifically this work examines the process by which the catalyst was aged and tested and presents a timeline of catalyst degradation under commercially relevant circumstances. The catalyst was aged in the field for 2 month intervals in the exhaust slipstream of a GMVH-12 engine and intermittently brought back to the Colorado State Engines and Energy Conversion Laboratory for both engine testing and catalyst surface analysis. Engine testing consisted of measuring catalyst reduction efficiency as a function of temperature as well as the determination of the light-off temperature for several exhaust components. The catalyst surface was analyzed via SEM/EDS and XPS techniques to examine the location and rate of poison deposition. After 2 years on-line the catalyst light-off temperature had increased ∼55°F (31°C) and ∼34 wt% poisons (S, P, Zn) were built up on the catalyst surface, both of which represent significant catalyst deactivation.

The role of oxidation catalyst in dual-catalyst bed for after-treatment of lean burn natural gas exhaust

2012 ◽  
Vol 197 (1) ◽  
pp. 127-136 ◽  
Author(s):  
Preshit Gawade ◽  
Anne-Marie C. Alexander ◽  
Ryan Clark ◽  
Umit S. Ozkan
Keyword(s):  
Natural Gas ◽  
Oxidation Catalyst ◽  
Lean Burn

Performance Degradation and Poison Build-Up of an Oxidation Catalyst in Two-Stroke Natural Gas Engine Exhaust

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Marc E. Baumgardner ◽  
Daniel B. Olsen
Keyword(s):  
Natural Gas ◽  
Photoelectron Spectroscopy ◽  
Catalyst Deactivation ◽  
Catalyst Surface ◽  
Oxidation Catalyst ◽  
Lean Burn ◽  
Gas Field ◽  
X Ray ◽  
Engine Testing ◽  
Carry Over

Due to current and future exhaust emissions regulations, oxidation catalysts are increasingly being added to the exhaust streams of large-bore, two-stroke, natural gas engines. Such catalysts have a limited operational lifetime, primarily due to chemical (i.e., catalyst poisoning) and mechanical fouling resulting from the carry-over of lubrication oil from the cylinders. It is critical for users and catalyst developers to understand the nature and rate of catalyst deactivation under these circumstances. This study examines the degradation of an exhaust oxidation catalyst on a large-bore, two-stroke, lean-burn, natural gas field engine over the course of 2 years. Specifically, this work examines the process by which the catalyst was aged and tested and presents a timeline of catalyst degradation under commercially relevant circumstances. The catalyst was aged in the field for 2-month intervals in the exhaust slipstream of a GMVH-12 engine and intermittently brought back to Colorado State University for both engine testing and catalyst surface analysis. Engine testing consisted of measuring catalyst reduction efficiency as a function of temperature as well as the determination of the light-off temperature for several exhaust components. The catalyst surface was analyzed via scanning electron microscope (SEM)/energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) techniques to examine the location and rate of poison deposition. After 2 years online, the catalyst light-off temperature had increased ∼55 °F (31 °C) and ∼34 wt % poisons (S, P, Zn) were built up on the catalyst surface, both of which represent significant catalyst deactivation.

A phenomenological model for the description of unburned hydrocarbons emission in ultra-lean engines

2021 ◽  
pp. 146808742110050
Author(s):  
Enrica Malfi ◽  
Vincenzo De Bellis ◽  
Fabio Bozza ◽  
Alberto Cafari ◽  
Gennaro Caputo ◽  
...  
Keyword(s):  
Natural Gas ◽  
Internal Combustion Engines ◽  
Pollutant Emissions ◽  
Average Error ◽  
Combustion Engines ◽  
Nitric Oxides ◽  
Lean Burn ◽  
Fuel Charge ◽  
Unburned Hydrocarbons ◽  
Model Reliability

The adoption of lean-burn concepts for internal combustion engines working with a homogenous air/fuel charge is under development as a path to simultaneously improve thermal efficiency, fuel consumption, nitric oxides, and carbon monoxide emissions. This technology may lead to a relevant emission of unburned hydrocarbons (uHC) compared to a stoichiometric engine. The uHC sources are various and the relative importance varies according to fuel characteristics, engine operating point, and some geometrical details of the combustion chamber. This concern becomes even more relevant in the case of engines supplied with natural gas since the methane has a global warming potential much greater than the other major pollutant emissions. In this work, a simulation model describing the main mechanisms for uHC formation is proposed. The model describes uHC production from crevices and flame wall quenching, also considering the post-oxidation. The uHC model is implemented in commercial software (GT-Power) under the form of “user routine”. It is validated with reference to two large bore engines, whose bores are 31 and 46 cm (engines named accordingly W31 and W46). Both engines are fueled with natural gas and operated with lean mixtures (λ > 2), but with different ignition modalities (pre-chamber device or dual fuel mode). The engines under study are preliminarily schematized in the 1D simulation tool. The consistency of 1D engine schematizations is verified against the experimental data of BMEP, air flow rate, and turbocharger rotational speed over a load sweep. Then, the uHC model is validated against the engine-out measurements. The averaged uHC predictions highlight an average error of 7% and 10 % for W31 and W46 engines, respectively. The uHC model reliability is evidenced by the lack of need for a case-dependent adjustment of its tuning constants, also in presence of relevant variations of both engine load and ring pack design.

scholarly journals Performance and Regeneration of Methane Oxidation Catalyst for LNG Ships

2021 ◽  
Vol 9 (2) ◽  
pp. 111
Author(s):  
Kati Lehtoranta ◽  
Päivi Koponen ◽  
Hannu Vesala ◽  
Kauko Kallinen ◽  
Teuvo Maunula
Keyword(s):  
Methane Oxidation ◽  
Sulfur Poisoning ◽  
Oxidation Catalyst ◽  
Lean Burn ◽  
Marine Fuel ◽  
Efficient Catalyst ◽  
Worst Case ◽  
Exhaust Temperature ◽  
Unintended Effect ◽  
Methane Slip

Liquefied natural gas (LNG) use as marine fuel is increasing. Switching diesel to LNG in ships significantly reduces air pollutants but the methane slip from gas engines can in the worst case outweigh the CO2 decrease with an unintended effect on climate. In this study, a methane oxidation catalyst (MOC) is investigated with engine experiments in lean-burn conditions. Since the highly efficient catalyst needed to oxidize methane is very sensitive to sulfur poisoning a regeneration using stoichiometric conditions was studied to reactivate the catalyst. In addition, the effect of a special sulfur trap to protect the MOC and ensure long-term performance for methane oxidation was studied. MOC was found to decrease the methane emission up to 70–80% at the exhaust temperature of 550 degrees. This efficiency decreased within time, but the regeneration done once a day was found to recover the efficiency. Moreover, the sulfur trap studied with MOC was shown to protect the MOC against sulfur poisoning to some extent. These results give indication of the possible use of MOC in LNG ships to control methane slip emissions.

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