An <i>in situ</i> temperature‐programmed XPS study of the surface chemical reactions of thiophene with Ag/titania

Samokhvalov, Alexander; Duin, Eduardus C.; Nair, Sachin; Tatarchuk, Bruce J.

doi:10.1002/sia.3314

Cited by 21 publications

(10 citation statements)

References 52 publications

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“…These results indicate the formation of inorganic rather than organic sulfur compounds during regeneration. Similar results were reported by Samokhvalov et al, who investigated the thermally induced desorption of thiophene from Ag-modified titania under a high vacuum. In their work, the surface sulfur content dropped by one-half after the adsorbent was annealed at 525 °C under XPS conditions (working pressure of 10 –8 –10 –6 Torr).…”

Section: Resultssupporting

confidence: 89%

Thermal in Situ and System-Integrated Regeneration Strategy for Adsorptive On-Board Desulfurization Units

et al. 2017

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This work deals with the introduction and investigation of a novel system-integrated thermal regeneration strategy based on hot off-gas for on-board desulfurization units. A highly thermally stable Ag–Al2O3 material was used as the adsorbent because it has the advantage of being active in the oxidized form so that it requires no activation after regeneration in an oxidative atmosphere. Dibenzothiophene (DBT) was used as the representative polycyclic aromatic sulfur heterocycle (PASH) in Jet A-1 fuel with a total sulfur concentration of 900 ppmw. This PASH has a stronger adsorption energy and is significantly more stable than benzothiophene or thiophene. This is why oxidative thermal regeneration strategies had formerly been failing to fully regenerate any type of adsorbent after the adsorption of DBT. This work reports excellent regeneration results upon the use of the hot off-gas from a solid-oxide-fuel-cell- (SOFC-) driven auxiliary power unit (APU) as the regeneration medium. The highly thermally stable Ag–Al2O3 showed a high breakthrough adsorption capacity of 2.2 mg-S/g-adsorbent in the first desulfurization cycle that was fully recovered by regeneration with hot APU off-gas. This is the first time that 100% regeneration has been reported for thermal regeneration after the adsorption of DBT. Additional investigations were performed to gain deeper insight into the overall desorption mechanism. The H2O content has an especially significant influence on the overall desorption mechanism of DBT. With a H2O content of 12.4 mol %, full regeneration was also obtained by reducing the final regeneration temperature from 525 to 450 °C. The results reported herein show that this novel regeneration strategy requires no additional regeneration medium, no additional tanks, and no additional bulky equipment and is thus fully integrated into the concept of an SOFC-operated APU.

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Section: Resultssupporting

confidence: 89%

Thermal in Situ and System-Integrated Regeneration Strategy for Adsorptive On-Board Desulfurization Units

et al. 2017

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“…To our knowledge, such experiment was never reported for H 2 S sorbents, even though the application of the in situ temperature-programmed XPS (TPXPS) for studies of oxidative regeneration of ''spent'' desulfurization sorbents for liquid fuels was reported recently. 101,102 Instrumental techniques based on measurement of spin states of ions may be very useful for Operando studies of sulfudation or regeneration reactions of H 2 S sorbents, due to being intrinsically non-destructive to the specimen, since photon energy is very small. However, Zn 2+ cation with electronic configuration [Ar] 4s 0 3d 10 is diamagnetic; therefore, electron spin resonance methods such as ESR and electron nuclear double resonance (ENDOR) do not allow to detect Zn 2+ cation directly.…”

Section: Real-time In Situ and Operando Techniques For Studying Zn An...mentioning

confidence: 99%

Characterization of active sites, determination of mechanisms of H2S, COS and CS2 sorption and regeneration of ZnO low-temperature sorbents: past, current and perspectives

Samokhvalov

Tatarchuk

2011

Phys. Chem. Chem. Phys.

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111

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The intellectually and technically challenging pursuit of the emerging global environmentally "green" and energy-efficient infrastructure of the 21st century requires the development of a worldwide network of low- to medium-power fuel cell (FC) based portable electric power-generating devices and high-power biomass/clean coal "electric+chemical plants" with zero carbon footprint utilizing integrated coal gasification combined cycle with geologic carbon sequestration (IGCC-GCS) under energy-efficient low-temperature conditions. These emerging technologies require the deep and ultradeep desulfurization of gaseous feeds, since sulfur compounds, especially hydrogen sulfide H(2)S are highly corrosive and poisonous to both technological processes and the environment. Therefore, it is of crucial importance for both academic and industrial research communities to have a solid understanding of the atomic-level structures of active sites and molecular-level mechanisms of surface chemical reactions of the novel deep and ultradeep desulfurization materials, especially desulfurization sorbents. This review critically analyzes the recent literature (last ∼20 years) on the experimental determination of molecular and atomic-level nature of adsorption sites, effects of desulfurization promoters, mechanisms of chemical reactions of H(2)S, COS and CS(2) and physical processes during and upon regeneration of "spent" low-temperature H(2)S sorbents based on ZnO that were developed for desulfurization of fuel reformates, syngas and similar streams. Recent trends in research on the ultradeep H(2)S sorbents are discussed with an impetus on real-time in situ and Operando techniques of instrumental chemical analysis, and the challenges of direct determination of the structure of active sites and of the experimental mechanistic studies in general are described.

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“…As a result, a number of techniques have been used for characterizing this system. Transmission electron microscopy (TEM), electron paramagnetic resonance (EPR), X-ray diffraction (XRD), and oxygen chemisorption (OC) have been previously employed in an attempt to elucidate the surface behavior of this adsorbent [1][2][3][4]. Silver atom dispersion and crystallite size are two crucial factors that influence capacity and selectivity of the adsorbent.…”

Section: Introductionmentioning

confidence: 99%

Understanding the dispersion of Ag on high surface area TiO2 supports using XPS intensity ratios

Davis¹,

Tatarchuk²

2015

Applied Surface Science

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An in situ temperature‐programmed XPS study of the surface chemical reactions of thiophene with Ag/titania

Cited by 21 publications

References 52 publications

Thermal in Situ and System-Integrated Regeneration Strategy for Adsorptive On-Board Desulfurization Units

Thermal in Situ and System-Integrated Regeneration Strategy for Adsorptive On-Board Desulfurization Units

Characterization of active sites, determination of mechanisms of H2S, COS and CS2 sorption and regeneration of ZnO low-temperature sorbents: past, current and perspectives

Understanding the dispersion of Ag on high surface area TiO2 supports using XPS intensity ratios

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