Kinetic study of adsorption and desorption of SO2 over γ-Al2O3 and Pt/γ-Al2O3

Hamzehlouyan, Tayebeh; Sampara, Chaitanya S.; Li, Junhui; Kumar, Ashok; Epling, William S.

doi:10.1016/j.apcatb.2015.08.003

Cited by 56 publications

(31 citation statements)

References 32 publications

(54 reference statements)

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“…These lead to formation of adsorbed sulfur species, surface sulfites/sulfates and bulk sulfation of both, the noble metal particles as well as the support [6]. While the transition of catalytically active Pd/PdO to inactive PdSO4 is claimed to be the main reason for activity loss [7], the poisoning of the support material results in even more severe effects, as the sulfur is stored and can spillover back to the noble metal particles [8]. Although addition of Pt is reported to increase the activity and stability to some extent [9], deactivation of Pd-Pt catalysts occurs with time on stream and therefore regeneration procedures are needed.…”

Section: Introductionmentioning

confidence: 99%

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: 99%

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

et al. 2018

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“…These peaks are most likely attributed to the adsorption of different species over alumina, where the peak at 1617 cm −1 is particularly associated with water bound to the alumina surface as a result of the release of OH groups from the alumina surface [4,29,37]. The peaks developed between 1540 and 1585 cm −1 are attributed to the interaction of the weakly absorbed SO 2 species with Al n+ Lewis acid sites [46]. Figure 5 shows the in situ DRIFTS spectra for Pt/Mg/Al 2 O 3 , Pd/Mg/Al 2 O 3 , and Pt/Pd/Mg/Al 2 O 3 samples during the exposure to 50 ppm of SO 2 and 8% O 2 for 2 h at 200 • C. Similar spectrum were observed for all three samples, characterized predominantly by a broad band centered at 1098 cm −1 .…”

Section: Influence Of Sulfur On Different Precious Metal Speciesmentioning

confidence: 98%

Sulfur Poisoning Effects on Modern Lean NOx Trap Catalysts Components

2019

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In the present work, a series of different materials was investigated in order to enhance the understanding of the role of modern lean NO x trap (LNT) components on the sulfur poisoning and regeneration characteristics. Nine different types of model catalysts were prepared, which mainly consisted of three compounds: (i) Al 2 O 3 , (ii) Mg/Al 2 O 3 , and (iii) Mg/Ce/Al 2 O 3 mixed with Pt, Pd, and Pt-Pd. A micro flow reactor and a diffuse reflectance infrared Fourier transform spectrometer (DRIFTS) were employed in order to investigate the evolution and stability of the species formed during SO 2 poisoning. The results showed that the addition of palladium and magnesium into the LNT formulation can be beneficial for the catalyst desulfation due mainly to the ability to release the sulfur trapped at relatively low temperatures. This was especially evident for Pd/Mg/Al 2 O 3 model catalyst, which demonstrated an efficient LNT desulfation with low H 2 consumption. In contrast, the addition of ceria was found to increase the formation of bulk sulfate species during SO 2 poisoning, which requires higher temperatures for the sulfur removal. The noble metal nature was also observed to play an important role on the SO x storage and release properties. Monometallic Pd-based catalysts exhibited the formation of surface palladium sulfate species during SO 2 exposure, whereas Pt-Pd bimetallic formulations presented higher stability of the sulfur species formed compared to the corresponding Pt-and Pd-monometallic samples.Catalysts 2019, 9, 492 2 of 18 urea [4]. Nevertheless, the LNT system is highly susceptible to sulfur, and its performance can be severely affected as NO x storage sites are blocked by sulfur [5][6][7]. Sulfates formed on the NO x storage sites have higher thermal stability than nitrates and nitrites and, therefore, their decomposition needs very high temperatures and alternating rich/lean exhaust mixtures [8,9]. This does not only lead to higher fuel consumption due to regular desulfation events, but may also cause structural deactivation of the catalyst, such as sintering of precious metals and the formation of mixed oxides (e.g., BaAl 2 O 4 for the reaction between Al 2 O 3 and BaO at high temperatures), affecting the overall NO x storage and reduction activity of the catalyst [10][11][12].Therefore, the sulfur tolerance of modern LNT catalysts should be improved by replacing the NO x trapping material with a component with lower affinity towards sulfation, and with enhanced desorption of sulfur species during regeneration. Barium is frequently employed as a storage material because of its high thermal stability, however, it is responsible for the major LNT catalyst deterioration due to its high affinity for sulfation [13]. Ji et al. [14] studied the incorporation of ceria to Ba-based LNT catalysts and determined to provide a positive impact on LNT performance in the presence of sulfur. Ceria was found to enhance sulfur tolerance of the LNT catalyst by storing sulfur species, which mitigates the sulfation o...

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“…Thus, coupling NTP technology with proper catalytic formulation is a suitable route to reduce, on one hand, the typical high temperature (400-900 • C) required for the thermal catalytic conversion of SO 2 , which promote surface sulfate formation and catalyst deactivation [50] and to increase, on the other hand, the selectivity of nonthermal plasma process. In this regard, various hybrid systems containing catalysts as well as photocatalysts have been investigated.…”

Section: Catalytic So 2 Removal Via Ntp Technologymentioning

confidence: 99%

A Review about the Recent Advances in Selected NonThermal Plasma Assisted Solid–Gas Phase Chemical Processes

et al. 2020

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Plasma science has attracted the interest of researchers in various disciplines since the 1990s. This continuously evolving field has spawned investigations into several applications, including industrial sterilization, pollution control, polymer science, food safety and biomedicine. nonthermal plasma (NTP) can promote the occurrence of chemical reactions in a lower operating temperature range, condition in which, in a conventional process, a catalyst is generally not active. The aim, when using NTP, is to selectively transfer electrical energy to the electrons, generating free radicals through collisions and promoting the desired chemical changes without spending energy in heating the system. Therefore, NTP can be used in various fields, such as NOx removal from exhaust gases, soot removal from diesel engine exhaust, volatile organic compound (VOC) decomposition, industrial applications, such as ammonia production or methanation reaction (Sabatier reaction). The combination of NTP technology with catalysts is a promising option to improve selectivity and efficiency in some chemical processes. In this review, recent advances in selected nonthermal plasma assisted solid–gas processes are introduced, and the attention was mainly focused on the use of the dielectric barrier discharge (DBD) reactors.

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Kinetic study of adsorption and desorption of SO2 over γ-Al2O3 and Pt/γ-Al2O3

Cited by 56 publications

References 32 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

Sulfur Poisoning Effects on Modern Lean NOx Trap Catalysts Components

A Review about the Recent Advances in Selected NonThermal Plasma Assisted Solid–Gas Phase Chemical Processes

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