Examination of the influence of La promotion on Ni state in hydrotalcite-derived catalysts under CO2 methanation reaction conditions: Operando X-ray absorption and emission spectroscopy investigation

Wierzbicki, Dominik; Baran, Rafał; Dębek, Radosław; Motak, Monika; Gálvez, María Elena; Grzybek, Teresa; Costa, Patrick Da; Glatzel, Pieter

doi:10.1016/j.apcatb.2018.03.089

Cited by 100 publications

(54 citation statements)

References 47 publications

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“…Higher Ni‐loading seems to accelerate sulfur deposition on the catalyst's surface due to the high affinity of Ni to sulfur and also to speed up carbon formation. It is frequently reported that Ni‐based catalysts easily suffered from carbon deposition in methanation reaction . In the case studied, with higher Ni‐loading of 30 wt % the benefits of Ni as a sulfur trap are weak and the drawbacks in form of carbon deposition predominate.…”

Section: Results Of Catalyst Testingmentioning

confidence: 96%

CO₂ Methanation in Microstructured Reactors – Catalyst Development and Process Design

et al. 2019

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The sulfur tolerance of mono‐ and bimetallic ruthenium catalysts for CO2 hydrogenation was investigated in microchannel reactors. H2S was selected as a model compound. It was found that a Ru/CeO2 catalyst deactivates rapidly. Ni was a much better additive to improve the catalyst stability compared to Rh and serves as a sulfur trap. The influence of the support was evaluated showing that a SiO2‐supported catalyst has a higher stability and better selectivity compared to CeO2 and TiO2. A plant concept was developed comprising two‐step methanation with a first adiabatic reactor stage followed by a plate heat‐exchanger reactor with integrated cooling which allows more than 97 % CO2 conversion. A pilot plant will be put into operation in connection with a biogas plant and an electrolyser of 50 kW power consumption.

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Section: Results Of Catalyst Testingmentioning

confidence: 96%

CO₂ Methanation in Microstructured Reactors – Catalyst Development and Process Design

et al. 2019

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“…Oxidation states lower than +4 derived from fitting the Kβ1,3 XES may be attributed to the imperfect choice of reference spectra and should be treated rather as a trend, Kβ1,3 analysis underestimating oxidation states was also found in case of Ni catalysts by Wierzbicki et al 52 On the other hand, a V 4+ / V 3+ redox couples have also been reported to exist in V SCR catalysts. 56 Regarding the coordination of V sites in the grafted catalysts, V sites demonstrate different coordination geometries.…”

Section: Operando Herfd-xanes / Vtc-xes On Grafted Catalystsmentioning

confidence: 92%

“…4a) are only weakly sensitive to the ligand environment and can be used to derive oxidation states of transition metals. 52 Position of the rising edge in the XANES spectra ( Fig. 4c) number of V sites.…”

Section: Conditions and Nh3-scrmentioning

confidence: 99%

NH₃-SCR over V–W/TiO₂ Investigated by Operando X-ray Absorption and Emission Spectroscopy

et al. 2019

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V-W/TiO2 based catalysts, which are used for the removal of NOx from the exhaust of diesel engines and stationary sources via Selective Catalytic Reduction with NH3 (NH3-SCR), were studied by operando X-ray absorption spectroscopy and emerging photon-in/photon-out techniques. In order to minimize the influence of highly X-ray absorbing tungsten and the fluorescence of titanium we used a high energy resolution fluorescence setup that is able to separate efficiently the V Kβ1,3 emission lines and additionally allows to record valence-to-core (vtc) X-ray emission lines. The High Energy Resolution Fluorescence Detected X-ray Absorption Spectroscopy (HERFD-XAS) and vtc X-ray Emission Spectroscopy (vtc-XES) proved to be the only way to perform operando V K edge X-ray spectroscopic study on industrially relevant V-W/TiO2 catalysts so far. The V-W/TiO2 and V/TiO2 samples were synthesized by incipient wetness impregnation and grafting and exhibit high activity towards NH3-SCR. Raman spectroscopy showed that they mainly contained highly dispersed, isolated and polymeric V-oxo species. HERFD-XAS and XES identified redox cycling of vanadium species between V 4+ and V 5+. However, no direct chemical bond between V and N was observed. As result of the obtained information we suggest that the primary role of V species in SCR is to provide redox sites, whereas, adsorption and reaction of NOx and NHx species may occur via the neighboring O atoms or on the acidic support.

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“…As depicted in Figure 1D, two small peaks in low temperature regions (100 °C and 280 °C) and intense peaks in high temperature regions about 760 °C. It is largely considered that the peaks at lower temperature regions can be credited to the weak basic sites resulting from the physical adsorption of CO2 [29]. While the peak appearing at the high temperature relates to the strong basic sites attributed to the chemisorption of CO2.…”

Section: Catalyst Characterizationmentioning

confidence: 99%

Effect of Pressure on Na0.5La0.5Ni0.3Al0.7O2.5 Perovskite Catalyst for Dry Reforming of CH4

et al. 2020

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In this paper, a comprehensive study was carried out on the application of perovskite catalyst in dry reforming of CH4. The perovskite catalyst was prepared using a sol–gel method. The prepared samples were characterized by N2 adsorption/desorption, TPR, XRD, CO2-TPD, TGA, TPO, Raman, and SEM techniques. In addition, the effect of operating pressure, namely, 1 bar, 3 bar, 5 bar, and 7 bar, temperature (500–800 °C) was evaluated. The characterization results indicated that catalysts operated at 1 bar, gas hourly space velocity of 84000 (mL/g/h) gave the best catalytic performance. CH4 and CO2 conversions of 77 and 80% were obtained at 1 bar and at 700 °C reaction temperature. The increase of reaction temperatures from 500 °C to 800 °C increased the reaction rate and hence the methane and carbon dioxide conversions were increased. A unity ratio of H2/CO was obtained at 1 bar for temperatures 600 °C and above. Similarly, the time on stream tests, obtained at a 700 °C reaction temperature, showed that the best ratio in terms of the closeness of unity and the stable profile could be attained when the pressure was set to 1 bar. The TGA analysis showed the drop of mass due to oxidation of carbon deposits, which started at 500 °C. The catalyst operated at 1 bar produced the least amount of carbon, equivalent to 35% weight loss, while the 3 and 5 bar operated catalysts generated carbon formation, equivalent to 65% weight loss. However, the 7 bar operated catalyst resulted the highest accumulation of carbon formation, equivalent to 83% weight reduction. Hence, the TGA profile indicated the relative carbon deposition on the catalyst, which was dependent of the operated pressure and hence confirmed the suitability operation pressure of 1 bar. The characterizations of the Raman, EDX, TGA, and TPO all presented the formation of carbon.

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Examination of the influence of La promotion on Ni state in hydrotalcite-derived catalysts under CO2 methanation reaction conditions: Operando X-ray absorption and emission spectroscopy investigation

Cited by 100 publications

References 47 publications

CO₂ Methanation in Microstructured Reactors – Catalyst Development and Process Design

CO₂ Methanation in Microstructured Reactors – Catalyst Development and Process Design

NH₃-SCR over V–W/TiO₂ Investigated by Operando X-ray Absorption and Emission Spectroscopy

Effect of Pressure on Na0.5La0.5Ni0.3Al0.7O2.5 Perovskite Catalyst for Dry Reforming of CH4

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Examination of the influence of La promotion on Ni state in hydrotalcite-derived catalysts under CO2 methanation reaction conditions: Operando X-ray absorption and emission spectroscopy investigation

Cited by 100 publications

References 47 publications

CO2 Methanation in Microstructured Reactors – Catalyst Development and Process Design

CO2 Methanation in Microstructured Reactors – Catalyst Development and Process Design

NH3-SCR over V–W/TiO2 Investigated by Operando X-ray Absorption and Emission Spectroscopy

Effect of Pressure on Na0.5La0.5Ni0.3Al0.7O2.5 Perovskite Catalyst for Dry Reforming of CH4

Contact Info

Product

Resources

About

CO₂ Methanation in Microstructured Reactors – Catalyst Development and Process Design

CO₂ Methanation in Microstructured Reactors – Catalyst Development and Process Design

NH₃-SCR over V–W/TiO₂ Investigated by Operando X-ray Absorption and Emission Spectroscopy