A detailed kinetic model for biogas steam reforming on Ni and catalyst deactivation due to sulfur poisoning

Appari, Srinivas; Janardhanan, Vinod M.; Bauri, Ranjit; Jayanti, S.; Deutschmann, Olaf

doi:10.1016/j.apcata.2013.12.002

Cited by 84 publications

(78 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As has been reported by other authors, the deactivation by sulfur can be described by the following general reaction Equation (8) [32,33], which is proposed to operate at high temperature:…”

Section: Catalystsmentioning

confidence: 86%

Catalyst Deactivation and Regeneration Processes in Biogas Tri-Reforming Process. The Effect of Hydrogen Sulfide Addition

et al. 2018

View full text Add to dashboard Cite

Abstract:This work studies Ni-based catalyst deactivation and regeneration processes in the presence of H 2 S under a biogas tri-reforming process for hydrogen production, which is an energy vector of great interest. 25 ppm of hydrogen sulfide were continuously added to the system in order to provoke an observable catalyst deactivation, and once fully deactivated two different regeneration processes were studied: a self-regeneration and a regeneration by low temperature oxidation. For that purpose, several Ni-based catalysts and a bimetallic Rh-Ni catalyst supported on alumina modified with CeO 2 and ZrO 2 were used as well as a commercial Katalco 57-5 for comparison purposes. Ni/Ce-Al 2 O 3 and Ni/Ce-Zr-Al 2 O 3 catalysts almost recovered their initial activity. For these catalysts, after the regeneration under oxidative conditions at low temperature, the CO 2 conversions achieved-79.5% and 86.9%, respectively-were significantly higher than the ones obtained before sulfur poisoning-66.7% and 45.2%, respectively. This effect could be attributed to the support modification with CeO 2 and the higher selectivity achieved for the Reverse Water-Gas-Shift (rWGS) reaction after catalysts deactivation. As expected, the bimetallic Rh-Ni/Ce-Al 2 O 3 catalyst showed higher resistance to deactivation and its sulfur poisoning seems to be reversible. In the case of the commercial and Ni/Zr-Al 2 O 3 catalysts, they did not recover their activity.

show abstract

Section: Catalystsmentioning

confidence: 86%

Catalyst Deactivation and Regeneration Processes in Biogas Tri-Reforming Process. The Effect of Hydrogen Sulfide Addition

et al. 2018

View full text Add to dashboard Cite

show abstract

“…iments performed by Appari 43 in the presence of H 2 S, and model predictions using the mechanism borrowed for use in this work 37 is shown in Figure 4. The figure shows the model predicted and experimentally observed gas-phase composition on a dry basis at the exit of a fixed bed reactor (Ni/γ-Al 2 O 3 ) operating at 800…”

Section: Resultsmentioning

confidence: 99%

“…To simulate a gas mixture consisting of H 2 , H 2 O, and H 2 S, it is sufficient to consider the subset of reactions proposed by Appari et al, 37 given in Table I. This reaction set consists of 16 reversible reactions among 5 gas-phase species (H 2 , H 2 O, O 2 , H 2 S, SO 2 ), 10 surface adsorbed species (H, O, S, OH, H 2 O, H 2 S, SO 2 , SH, SO, SH) on Ni, and the vacant sites on the catalytic surface of Ni.…”

Section: R Nomentioning

confidence: 99%

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

Janardhanan

Monder

2014

J. Electrochem. Soc.

Self Cite

View full text Add to dashboard Cite

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...

show abstract

“…MgO is a strong Lewis base and has a high adsorption of CO2 in the reduction or prevention of carbon deposition. Besides, the reduction of ZrO2 in the ZrO2-MgO solid solution was more difficult, often causing the smaller particles of zirconium to be formed on the topmost layer compared with that of unadulterated ZrO2 [32,33]. When surface basicity combines with the particle size of small metals, the MgO-based solid solution catalyst can prevent carbon deposition more effectively.…”

Section: Effects Of Reactant Concentration On Conversionmentioning

confidence: 99%

Effects of Platinum and Palladium Metals on Ni/Mg1-xZrxO Catalysts in the CO2 Reforming of Methane

Al-Doghachi

2018

Bull. Chem. React. Eng. Catal.

View full text Add to dashboard Cite

Nickel, palladium, and platinum catalysts (1 wt.% each) supported on MgO and MgZrO to prepare Pt,Pd,Ni/Mg1-xZrxO catalysts (where x = 0, 0.03, 0.07, and 0.15), were synthesized by using coprecipitation method with K2CO3 as the precipitant. X-ray diffraction (XRD), X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), H2-temperature programmed reduction (H2-TPR), and thermo gravimetric analysis (TGA) were employed to observe the characteristics of the prepared catalysts. The Pt,Pd,Ni/Mg0.85Zr0.15O showed the best activity in dry reforming of methane (DRM) with 99 % and 91 % for CO2 and CH4 conversions, respectively and 1.28 for H2/CO ratio at temperature 900 °C and 1:1 of CH4:CO2 ratio. The stability of Pt,Pd,Ni/Mg0.85Zr0.15O catalyst in the presence and absence of low stream 1.25 % oxygen was investigated. Carbon formation and amount in spent catalysts were examined by TEM and TGA in the presence of stream oxygen. The results showed that the amount of carbon was suppressed and negligible coke formation (less than 3 %) was observed. Several effects were observed with ZrO2 use as a promoter in the catalyst. Firstly, the magnesia cubic phase stabilized. Secondly, thermal stability and support for basicity increased. Thirdly, carbon deposition and the reducibility of Ni 2+ , Pd 2+ , and Pt 2+ ions decreased.

show abstract

A detailed kinetic model for biogas steam reforming on Ni and catalyst deactivation due to sulfur poisoning

Cited by 84 publications

References 32 publications

Catalyst Deactivation and Regeneration Processes in Biogas Tri-Reforming Process. The Effect of Hydrogen Sulfide Addition

Catalyst Deactivation and Regeneration Processes in Biogas Tri-Reforming Process. The Effect of Hydrogen Sulfide Addition

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

Effects of Platinum and Palladium Metals on Ni/Mg1-xZrxO Catalysts in the CO2 Reforming of Methane

Contact Info

Product

Resources

About