Catalytic combustion of ventilation air methane (VAM) – long term catalyst stability in the presence of water vapour and mine dust

Setiawan, Adi; Friggieri, Jarrod; Kennedy, Eric M.; Dlugogorski, Bogdan Z.; Stockenhuber, Michael

doi:10.1039/c4cy00120f

Cited by 28 publications

(35 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the presence of water at high temperature can promote Pd sintering. [34] Notably, on those catalysts, the high temperature PdO-Pd phase transition leads also to a significant decrease of catalytic activity even under dry conditions. What we have observed in the present study is that there is an additional deactivation process that occurs on the Pd@CeO 2 /Si-Al 2 O 3 core-shell catalysts during oxidation of methane in the presence of water vapor at high temperatures.…”

mentioning

confidence: 99%

Methane Catalytic Combustion over Hierarchical Pd@CeO₂/Si‐Al₂O₃: Effect of the Presence of Water

et al. 2014

View full text Add to dashboard Cite

The influence of water vapor on methane catalytic combustion was studied over a Pd@CeO2/Si‐Al2O3 catalyst, carefully designed to maximize Pd‐CeO2 interaction and prevent metal sintering and compared to a conventional impregnated catalyst with identical chemical composition. Although the nanostructured Pd@CeO2/Si‐Al2O3 catalyst is thermally stable, the addition of water to the reaction feed leads to a transient deactivation at low temperatures, consistent with the well documented competitive adsorption. In addition to this, the hierarchically structured catalyst exhibits an additional severe deactivation after methane oxidation in the presence of water vapor at 600 °C that can be reversed only by heating the catalyst above 700 °C. The presence of water in the reaction feed deactivates the conventional impregnated catalyst less severely and the activity largely returns upon water removal. Catalytic FTIR and CO‐chemisorption data indicate that this severe deactivation process in the hierarchical catalyst is due to the formation of stable OH groups on the surface of the ceria nanoparticles. These hydroxyl groups are suggested to significantly inhibit the oxygen spillover from the CeO2 nanoparticles to Pd, preventing its efficient re‐oxidation, as observed by operando X‐ray absorption near edge spectroscopy (XANES) experiments. At the same time, their presence can contribute to limit the gas phase accessibility of Pd, as indicated by the decrease of CO chemisorption capability. The presence of hydroxyls plays a minor role on the deactivation of the conventional catalyst at 600 °C.

show abstract

mentioning

confidence: 99%

Methane Catalytic Combustion over Hierarchical Pd@CeO₂/Si‐Al₂O₃: Effect of the Presence of Water

et al. 2014

View full text Add to dashboard Cite

show abstract

“…Vice versa, the wet aging at 600 8Cl eads to an appreciable decrease of the capability to chemisorb CO. Althoughs ignificant, the observed decrease of exposed metal surface area (Table 1) cannotalone explain the observed dramatic deactivation of the catalytic activity.R emarkably,t he initial Pd accessibility is fully recovered after the high temperature treatment that eliminates the hydroxyls groups and restores the catalytic activity.T he results for the conventional impregnated Pd-CeO 2 /Si-Al 2 O 3 were different and the initial accessible Pd surface area is only marginally reduced by either dry or wet aging (Table 1). [34] Notably,o nt hose catalysts, the high temperature PdO-Pdp hase transition leads also to as ignificant decrease of catalytic activity even under dry conditions. However,t he initial metal-support contact area, as indirectly indicated by the metal dispersion, is decreased, partially accounting for the lower activity Pd-CeO 2 based catalysts show very good low-temperaturea ctivity for methane oxidation, [2] especially when prepared in ah ierarchical structure that maximizes the contact between the PdO core the surrounding porous ceria.…”

Section: Resultsmentioning

confidence: 99%

Methane Catalytic Combustion over Hierarchical Pd@CeO₂/Si‐Al₂O₃: Effect of the Presence of Water

et al. 2015

View full text Add to dashboard Cite

show abstract

“…XPS analysis results of long-term used catalysts were reported previously. 8 Peak fitting under the spectra of calcined-reduced sample (Fig. 9a) reveals two components detected at Pd 3d 5/2 core-level.…”

Section: The Nature Of Aged Pd/al 2 O 3 Catalystsmentioning

confidence: 98%

Accelerated hydrothermal ageing of Pd/Al₂O₃ for catalytic combustion of ventilation air methane

Setiawan

Friggieri

Bryant

et al. 2015

Catal. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

In this report, the characteristics of Pd/Al 2 O 3 catalyst after long-term stability tests in catalytic combustion of simulated ventilation air methane gas were investigated with the objective of understanding catalyst deactivation phenomena. It was found that the deactivation is primarily due to palladium migration and particle growth and is the most prominent in the presence of water vapour. The formation of α-Al 2 O 3 during long-term stability tests explains the changes in pore structures which is responsible for re-dispersion of palladium particles. Four accelerated ageing procedures were performed with an aim of mimicking the properties of used catalysts which have been operating continuously for extended time periods (over 1100 h). XRD patterns of aged catalysts disclose the absence of an alpha-alumina phase, suggesting that the transformation of alumina phase occurred at a very slow rate. Among the four procedures, ageing under wet-oxidizing atmosphere provides the catalyst bed that is the best match to the properties of long-term used catalysts in terms of performance and the characterization employed. Increasing the aging temperature up to 830°C leads to depletion of surface palladium, which permanently reduces the performance of the catalyst. A IntroductionMethane is a gas with significant greenhouse warming potential whose atmospheric sources and sinks are well documented. 1 Nearly 10% of total anthropogenic methane emissions originate from coal mining activities, 2 and almost twothirds of these emissions originate from mine ventilation air. Reducing the greenhouse impact of this particular source presents significant challenges to mine operators, the most notable being that ventilation air methane (VAM) is a low concentration, high volume stream that prevents the use of conventional combustion and energy recovery technologies. Low temperature catalytic combustion offers an alternative treatment method, which, when compared to high temperature combustion, presents the advantage to eliminate the generation of additional emissions to the air, such as nitrogen oxides. However, its viability depends on maintaining the activity of the catalyst bed during its exposure to high volumes of ventilation air that contains several components which have the potential to affect performance, such as water vapour and particulate matter.It is widely accepted that supported palladium materials comprise a group of the most effective catalysts for the low temperature oxidation of methane. 3 Under oxygen-rich conditions, PdO is formed and represents the active phase for methane oxidation. 3 It is suggested that water produced by reaction inhibits the activity of Pd-based catalysts due to competition with methane for the active sites. 4-6 Furthermore, the presence of water in the feed induces a transformation of the active sites (oxidised Pd) into a less active sites (most likely hydroxy species) and results in permanent deactivation. [4][5][6][7] The rate of catalyst deactivation due to water, either present in the feed o...

show abstract

Catalytic combustion of ventilation air methane (VAM) – long term catalyst stability in the presence of water vapour and mine dust

Abstract: This paper presents long-term evaluation of catalyst stability and durability in the presence of water and coal mine dust.

Cited by 28 publications

References 29 publications

Methane Catalytic Combustion over Hierarchical Pd@CeO₂/Si‐Al₂O₃: Effect of the Presence of Water

Methane Catalytic Combustion over Hierarchical Pd@CeO₂/Si‐Al₂O₃: Effect of the Presence of Water

Methane Catalytic Combustion over Hierarchical Pd@CeO₂/Si‐Al₂O₃: Effect of the Presence of Water

Accelerated hydrothermal ageing of Pd/Al₂O₃ for catalytic combustion of ventilation air methane

Contact Info

Product

Resources

About

Catalytic combustion of ventilation air methane (VAM) – long term catalyst stability in the presence of water vapour and mine dust

Abstract: This paper presents long-term evaluation of catalyst stability and durability in the presence of water and coal mine dust.

Cited by 28 publications

References 29 publications

Methane Catalytic Combustion over Hierarchical Pd@CeO2/Si‐Al2O3: Effect of the Presence of Water

Methane Catalytic Combustion over Hierarchical Pd@CeO2/Si‐Al2O3: Effect of the Presence of Water

Methane Catalytic Combustion over Hierarchical Pd@CeO2/Si‐Al2O3: Effect of the Presence of Water

Accelerated hydrothermal ageing of Pd/Al2O3 for catalytic combustion of ventilation air methane

Contact Info

Product

Resources

About

Methane Catalytic Combustion over Hierarchical Pd@CeO₂/Si‐Al₂O₃: Effect of the Presence of Water

Methane Catalytic Combustion over Hierarchical Pd@CeO₂/Si‐Al₂O₃: Effect of the Presence of Water

Methane Catalytic Combustion over Hierarchical Pd@CeO₂/Si‐Al₂O₃: Effect of the Presence of Water

Accelerated hydrothermal ageing of Pd/Al₂O₃ for catalytic combustion of ventilation air methane