Sintering of nickel steam-reforming catalysts: effects of temperature and steam and hydrogen pressures

Sehested, Jens

doi:10.1016/j.jcat.2004.01.026

Cited by 275 publications

(88 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the other hand, the water effect on this mechanism is not yet fully understood. There are evidences confirming an increase in Ni mobility due to the formation of a Ni2-OH dimer complex [24]. Other authors also suggest the formation of a Ni(OH)2 hydroxide [25].…”

Section: Introductionmentioning

confidence: 76%

The influence of the reducing conditions on the final microstructure and performance of nickel-yttria stabilized zirconia cermets

Monzón

Laguna‐Bercero

2016

Electrochimica Acta

View full text Add to dashboard Cite

Ni-YSZ (yttria stabilized zirconia) cermets are the most widespread composite materials to be used as SOFC fuel electrodes. These materials are generally fabricated by the reduction of NiO to Ni in a NiO-YSZ composite, where the reducing conditions have a great effect in the final microstructure of the electrode. In the present work, several reducing conditions were explored in order to find the most suitable microstructure for anode-supported microtubular solid oxide fuel cells (SOFCs). Samples were firstly reduced in either pure or diluted H2 (dry or humidified), at temperatures ranging from 400 to 800 °C while their DC conductivity was monitored. The highest conductivity value was measured for the sample reduced in pure humidified hydrogen at 800°C. However, this sample experienced conductivity degradation in comparison with samples reduced under dry conditions. For the studied temperature range, nucleation of nano-porous nickel particles is firstly formed during reduction. However, from our experiments it was concluded that those nanoparticles are not stable with time, at least at temperatures between 600 ºC and 800 ºC. Electrochemical characterization of complete microtubular cells under real wet conditions was also performed under current load, confirming that the microstructure of the Ni-YSZ cermet is still evolving during operation.

show abstract

Section: Introductionmentioning

confidence: 76%

The influence of the reducing conditions on the final microstructure and performance of nickel-yttria stabilized zirconia cermets

Monzón

Laguna‐Bercero

2016

Electrochimica Acta

View full text Add to dashboard Cite

show abstract

“…Sehested et al [27,28] reported a decrease in surface area from 122 m 2 g -1 at 500 °C to 84.8 m 2 g -1 at 825 °C during their investigations on sintering of 9.5 wt.% Ni-Al2O3 catalyst.…”

Section: Characterization Of Reacted Catalystsmentioning

confidence: 98%

“…It has been reported [29] that the higher temperature and higher partial pressure of steam tend to promote sintering while increase in partial pressure of hydrogen showed an inhibitory effect on the sintering of nickel [27]. It has been suggested that the increase in the rate of sintering at higher temperature is due to the change of sintering mechanism from particle migration and coalescence (PMC) to Ostwald ripening (OR) [30].…”

Section: Characterization Of Reacted Catalystsmentioning

confidence: 99%

Pyrolysis/reforming of rice husks with a Ni–dolomite catalyst: Influence of process conditions on syngas and hydrogen yield

Waheed

2016

Journal of the Energy Institute

View full text Add to dashboard Cite

The influence of process conditions on the production of syngas and H2 from biomass in the form of rice husks was investigated using a two-stage pyrolysis-catalytic reforming reactor.The parameters investigated were, reforming temperature, steam flow rate and biomass particle size and the catalyst used was a 10 wt.% Ni-dolomite catalyst. Biomass was pyrolysed in the first stage, and the product volatiles were reformed in the second stage in the presence of steam and the Ni-dolomite catalyst. Increase in catalyst temperature from 850 °C to 1050 °C marginally improved total syngas yield. However, H2 yield was increased from 20.03 mmoles g -1 at 850 °C to 30.62 mmoles g -1 at 1050 °C and H2 concentration in the product gas increased from 53.95 vol.% to 65.18 vol.%. Raising the steam flow rate increased the H2 yield and H2 gas concentration. A significant increase in H2:CO ratio along with a decrease in CO:CO2 ratio suggested a change in the equilibrium of the water gas shift reaction towards H2 formation with increased steam flow rate. The influence of particle size on H2 yield was small showing an increase in H2 production when the particle size was reduced from 2.8 -3.3 to 0.2 -0.5 mm.

show abstract

“…This kind of high dispersion of Fe on the spinel catalyst could overcome its shortage of the much lower surface area compared to a mixture of oxides and contribute to the higher gas production and hydrogen yield during the thermo-chemical process. It should be noted that the spinel structure is thermally stable during the reaction and is resistant to sintering as reported by previous research [44][45][46]. In this research SEM was used to characterise the surface morphology of all the reacted catalysts.…”

Section: Coke Formationmentioning

confidence: 78%

Catalytic steam reforming of volatiles released via pyrolysis of wood sawdust for hydrogen-rich gas production on Fe–Zn/Al2O3 nanocatalysts

Chen

Dong

et al. 2015

Fuel

View full text Add to dashboard Cite

Abstract:Thermo-chemical processing of biomass is a promising alternative to produce renewable hydrogen as a clean fuel or renewable syngas for a sustainable chemical industry. However, the fast deactivation of catalysts due to coke formation and sintering limits the application of catalytic thermo-chemical processing in the emerging bio-refining industry. In this research, Fe-Zn/Al 2 O 3 nanocatalysts have been prepared for the production of hydrogen through pyrolysis catalytic reforming of wood sawdust. Through characterization, it was found that Fe and Zn were well distributed on the surface with a narrow particle size. During the reactions, the yield of hydrogen increased with the increase of Zn content, as Zn is an efficient metal promoter for enhancing the performance of the Fe active site in the reaction. The 20% Fe/Al 2 O 3 catalyst with Zn/Al ratio of 1:1 showed the best performance in the process in relation to the hydrogen production and resistance to coke formation on the surface of the reacted catalyst. All the catalysts showed ultra-high stability during the process and nearly no sintering were observed on the used catalysts. Therefore, the nanocatalysts prepared in this work from natural-abundant and low-cost metals have promising catalytic properties (high metal dispersion and stability) to produce H 2 -rich syngas with optimal H 2 /CO ratio from the thermo-chemical processing of biomass.

show abstract

Sintering of nickel steam-reforming catalysts: effects of temperature and steam and hydrogen pressures

Cited by 275 publications

References 32 publications

The influence of the reducing conditions on the final microstructure and performance of nickel-yttria stabilized zirconia cermets

The influence of the reducing conditions on the final microstructure and performance of nickel-yttria stabilized zirconia cermets

Pyrolysis/reforming of rice husks with a Ni–dolomite catalyst: Influence of process conditions on syngas and hydrogen yield

Catalytic steam reforming of volatiles released via pyrolysis of wood sawdust for hydrogen-rich gas production on Fe–Zn/Al2O3 nanocatalysts

Contact Info

Product

Resources

About