High temperature hydrogen sulfide chemisorption on nickel catalysts

Alstrup, I.; Rostrup-Nielsen, J.R.; Røen, Stig

doi:10.1016/0166-9834(81)80036-x

Cited by 110 publications

(93 citation statements)

References 12 publications

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“…As mentioned earlier, the experimental and empirical investigations of Alstrup et al 16 have shown that the enthalpy of adsorption for sulfur on nickel decreases with increasing sulfur coverage and they were able to fit a Temkin isotherm to experimental adsorption data. Hansen 17 then used the above Temkin isotherm to correlate the predicted sulfur coverage and the performance drop seen in SOFC sulfur poisoning experiments.…”

Section: R Nomentioning

confidence: 85%

“…In this approach the cell voltage is given by [16] where ϕ c and ϕ a are respectively the cathode and anode current collector potentials. Charge conservation in each phase leads to the following equations.…”

Section: Charge Transfer Throughout the Composite Electrodes (Model-imentioning

confidence: 99%

“…Attempts to describe the effect of fuel composition/temperature on sulfur poisoned SOFC performance have focused on the Temkin isotherm first reported by Alstrup et al, 16 which was fitted to a large set of experimental data for sulfur uptake on Ni based catalysts. Hansen 17 used this isotherm and showed that the observed performance drop was clearly correlated to the predicted sulfur coverage at the given inlet fuel composition and temperature.…”

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confidence: 99%

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Sulfur Poisoning of SOFCs: A Model Based Explanation of Polarization Dependent Extent of Poisoning

Janardhanan

Monder

2014

J. Electrochem. Soc.

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Several experimental studies have shown that, 1) the extent of the poisoning effect due to trace amounts of sulfur compounds in the fuel is lower if a SOFC is operated at a higher current density, and 2) the performance drop due to sulfur poisoning is much lower for Ni-GDC or Ni-ScSZ anodes when compared to Ni-YSZ anodes. This work presents a first principles numerical model that simulates experimental studies of sulfur poisoning on SOFC button cells. The exchange current densities for the electrodes are determined using sulfur-free polarization data for cells fueled by humidified mixtures of H 2 and N 2 . A detailed surface reaction model that predicts the fractional coverage of all adsorbed species at the three phase interface is coupled to the SOFC model and the sulfur coverage is used to alter the anode exchange current density. The resulting model predictions match experimental observations during both galvanostatic and potentiostatic operation. Our analysis shows that the observed lower performance drop at higher current density is due to the non-linear nature of the electrochemical rate equations, and that the lower impact of sulfur poisoning on Ni-GDC and Ni-ScSZ anodes (compared to Ni-YSZ anodes) is due to their higher electrochemical activity. Solid oxide fuel cell (SOFC) systems operating on natural gas or gasified coal can be significantly more energy efficient than today's combustion systems and can thus reduce CO 2 emissions. However, a major problem associated with the use of hydrocarbon fuels is the presence of sulfur containing compounds that are converted to H 2 S under SOFC operating conditions.1 The H 2 S present in the feed gas can readily deactivate conventional Ni cermet anodes. One can certainly have a desulfurization unit before the fuel cell stack to deal with the sulfur poisoning. However, this leads to increased system complexity and decrease in overall efficiency. Nevertheless, it is important to understand and quantify the sulfur tolerance of SOFC anodes in the event of sulfur breakthrough from the desulfurizer. Sulfur poisoning of Ni-YSZ anodes in SOFC is well studied experimentally for model fuel compositions consisting of ppm levels of H 2 S in mixtures of H 2 , H 2 O and an inert 2-4 as well as H 2 S in gas mixtures representative of natural gas or reformed natural gas.5-8 Most of the experimental literature deals with H 2 S concentrations well below 10 ppm and work that treats H 2 S concentrations higher than 20 ppm is rather limited. 2,5,8 On the other hand it is well known that natural gas and biogas can have substantially higher sulfur concentrations and that catalytic steam reforming of methane can be carried out on Ni even with 100 ppm H 2 S without losing all catalytic activity 9,10 e.g., a methane conversion (in model biogas) of ∼35% can be maintained using a supported Ni catalyst with 100 ppm H 2 S at 800• C. 10For an electrolyte supported cell Zha et al., 2 studied the cell performance for a wide range of H 2 S concentrations using DC polarization and electrochemical i...

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Section: R Nomentioning

confidence: 85%

Section: Charge Transfer Throughout the Composite Electrodes (Model-imentioning

confidence: 99%

mentioning

confidence: 99%

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Sulfur Poisoning of SOFCs: A Model Based Explanation of Polarization Dependent Extent of Poisoning

Janardhanan

Monder

2014

J. Electrochem. Soc.

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“…The sulfur uptake of the catalysts was determined by oxidation of the chemisorbed sulfur at high temperatures, using an infrared detector to measure the amount of SO 2 released. Under the experimental conditions used, the specific nickel surface area can be calculated from the sulfur capacity from the relationship that 440 ppm S is equivalent to a specific Ni surface area of 1 m 2 /g [1,25]. Ni surface areas determined by H 2 S chemisorption in this way give values similar to surface areas determined by H 2 chemisorption.…”

Section: Catalysts Characterizationmentioning

confidence: 99%

Sintering of Ni/Al2O3 catalysts studied by anomalous small angle X-ray scattering

Rasmussen

Sehested

Teunissen

et al. 2004

Applied Catalysis A: General

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“…The impact of siloxanes have been recently studied by Madi et al showing in detail post-mortem characterization of both single cells and a stack tested with D4-siloxane [18,19]. The scientific literature is quite vast on sulfur poisoning on Nianodes (Ni-YSZ anodes, especially, but also Ni-ScSZ), which has been the object of experimental and modeling studies since the 1980s [20].…”

Section: Introductionmentioning

confidence: 99%

Reporting Degradation from Different Fuel Contaminants in Ni‐anode SOFCs

et al. 2017

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The real-life operation of solid oxide fuel cell (SOFC) system has to deal with fuel contaminants which might reduce even significantly the lifetime of reformer and stack depending on the type and amount of contaminant present in the feed stream. From a system perspective, detecting and correlating observed stack and reformer performance degradation with fuel contamination is fundamental to implement correctional procedures (e.g., change of clean-up vessels catalysts) and/or trigger alarms to prevent a further contamination of the fuel cell. In this work, based on own experiments with several fuel contaminants (H 2 S, HCl, tars, siloxanes), we have developed empirical degradation models which are able to quantitatively correlate the range of degradation rate resulting from known amounts of a certain contaminant type in the fuel stream. Degradation induced by carbon deposition is also assessed using a simulation model. The techno-economic trade-off of having ultra-stringent purification requirements on the fuel clean-up unit due to additional operating costs (e.g., for frequent catalysts change) or capital costs (e.g., for vessel over-sizing to accommodate a larger amount of catalysts and possibly of different types) versus the lifetime of the fuel cell stacks is eventually analyzed.

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High temperature hydrogen sulfide chemisorption on nickel catalysts

Cited by 110 publications

References 12 publications

Sulfur Poisoning of SOFCs: A Model Based Explanation of Polarization Dependent Extent of Poisoning

Sulfur Poisoning of SOFCs: A Model Based Explanation of Polarization Dependent Extent of Poisoning

Sintering of Ni/Al2O3 catalysts studied by anomalous small angle X-ray scattering

Reporting Degradation from Different Fuel Contaminants in Ni‐anode SOFCs

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