Regeneration of sulfur-poisoned Pd-based catalyst for natural gas oxidation

Honkanen, Mari; Wang, Jianguang; Kärkkäinen, Mikko; Huuhtanen, Mika; Jiang, Hua; Kallinen, Kauko; Keiski, Riitta L.; Akola, Jaakko; Vippola, Minnamari

doi:10.1016/j.jcat.2017.12.021

Cited by 43 publications

(23 citation statements)

References 41 publications

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“…In this regard, rich conditions have been found very suited for reactivation [10]. However, the sulfur remaining on the support after regeneration at mild temperature conditions will re-poison the catalyst immediately after returning to reaction gas mixture, as recently observed for a Pd/Al2O3 catalyst [11].…”

Section: Introductionmentioning

confidence: 92%

Regeneration of Sulfur Poisoned Pd–Pt/CeO2–ZrO2–Y2O3–La2O3 and Pd–Pt/Al2O3 Methane Oxidation Catalysts

et al. 2018

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The poisoning of Pd-Pt/Al2O3 and Pd-Pt/CeO2-ZrO2-Y2O3-La2O3 methane oxidation catalysts by SO2 was studied under conditions typical for lean burn gas engines. Regeneration of sulfur-poisoned catalysts was achieved by applying rich conditions at 500 °C and 550 °C. The presence of NOx resulted in a slower deactivation rate. While Pd-Pt/CeO2-ZrO2-Y2O3-La2O3 showed a superior catalytic activity, durability and regeneration ability over Pd-Pt/Al2O3 under NOx-free reaction conditions, its reactivation by a rich treatment was strongly inhibited if NOx was present during the aging and regeneration process. Operando X-ray absorption spectroscopy (XAS) was used to monitor the evolution of Pd and Pt during poisoning and regeneration, revealing the formation of PdS and metallic Pd during reactivation of Pd-Pt/Al2O3, followed by transition to PdO after changing to lean reaction gas mixture. On the other hand, Pd species supported on CeO2-ZrO2-Y2O3-La2O3 could not be reduced by rich treatment and no regeneration occurred.

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Section: Introductionmentioning

confidence: 92%

Regeneration of Sulfur Poisoned Pd–Pt/CeO2–ZrO2–Y2O3–La2O3 and Pd–Pt/Al2O3 Methane Oxidation Catalysts

et al. 2018

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“…Sulfur originates from lubricant oil and natural gas, and it oxidizes further during the burning process to SO 2 , and on a catalyst, it further reacts with oxygen from SO 2 to SO 3 . It accumulates in the presence of water vapor over a catalyst as PdSO 4 and Al 2 (SO 4 ) 3 [7][8][9]. Attempts have been made to solve the disadvantage of sulfur poisoning on methane conversion activity by modifying washcoat materials [2,[10][11][12], and by varying noble metal content and their combinations [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Fundamentals of Sulfate Species in Methane Combustion Catalyst Operation and Regeneration—A Simulated Exhaust Gas Study

et al. 2019

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Emission regulations and legislation inside the European Union (EU) have a target to reduce tailpipe emissions in the transportation sector. Exhaust gas aftertreatment systems play a key role in low emission vehicles, particularly when natural gas or bio-methane is used as the fuel. The main question for methane operating vehicles is the durability of the palladium-rich aftertreatment system. To improve the durability of the catalysts, a regeneration method involving an efficient removal of sulfur species needs to be developed and implemented on the vehicle. This paper tackles the topic and its issues from a fundamental point of view. This study showed that Al2(SO4)3 over Al2O3 support material inhibits re-oxidation of Pd to PdO, and thus hinders the formation of the low-temperature active phase, PdOx. The presence of Al2(SO4)3 increases light-off temperature, which may be due to a blocking of active sites. Overall, this study showed that research should also focus on support material development, not only active phase inspection. An active catalyst can always be developed, but the catalyst should have the ability to be regenerated.

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“…An effective catalyst regeneration strategy is essential for ensuring an adequate durability and lifetime of the catalyst system. The regeneration process of sulfur-poisoned Pd catalysts is not well understood, as the research in the field has, so far, mostly focused on improving the catalyst regeneration efficiency and only few mechanistic studies have been published [2,[11][12][13]. The regeneration of a PdSO4/Al2O3 model catalyst under oxidative conditions has been observed to occur via a two-step reaction path, resulting eventually in the formation of metallic Pd, which can be oxidized to PdO [10].…”

Section: Introductionmentioning

confidence: 99%

Regeneration of a sulfur-poisoned methane combustion catalyst: Structural evidence of Pd4S formation

Nissinen

Kinnunen

Suvanto

2018

Applied Catalysis B: Environmental

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Decomposition of PdSO4, a species responsible for the deactivation of Pd-based methane combustion catalysts, was studied using a PdSO4/Al2O3 model system. PdSO4 was observed to behave differently under different reaction conditions. The decomposition of PdSO4 under inert atmosphere probably involved only one reaction step and resulted in the formation of metallic palladium. Under H2-containing atmosphere, the decomposition of PdSO4 resulted eventually in the formation of Pd4S, which is probably one of the many possible sulfur-containing palladium species that can be formed during regeneration of a sulfur-poisoned Pd-rich methane combustion catalyst. The formation of Pd4S can provide a reasonable explanation to the threshold temperature of sulfur removal from the catalyst, as well as to the residual sulfur present in the catalyst after regeneration under reductive atmosphere. Overall, the results obtained in the study provide deeper insight into the regeneration process of Pd-based catalysts, possibly enabling development of a more efficient regeneration strategy.

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Regeneration of sulfur-poisoned Pd-based catalyst for natural gas oxidation

Cited by 43 publications

References 41 publications

Regeneration of Sulfur Poisoned Pd–Pt/CeO2–ZrO2–Y2O3–La2O3 and Pd–Pt/Al2O3 Methane Oxidation Catalysts

Regeneration of Sulfur Poisoned Pd–Pt/CeO2–ZrO2–Y2O3–La2O3 and Pd–Pt/Al2O3 Methane Oxidation Catalysts

Fundamentals of Sulfate Species in Methane Combustion Catalyst Operation and Regeneration—A Simulated Exhaust Gas Study

Regeneration of a sulfur-poisoned methane combustion catalyst: Structural evidence of Pd4S formation

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