Preferential oxidation of CO on Ni/CeO2 catalysts in the presence of excess H2 and CO2

Malwadkar, Sachin; Bera, Parthasarathi; Hegde, M. S.; Satyanarayana, C.V.V.

doi:10.1007/s11144-012-0477-6

Cited by 14 publications

(14 citation statements)

References 43 publications

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“…In recent decades, researchers have focused on the development of base metals as catalysts for CO-PrOx with high CO oxidation activity and selectivity [4][5][6][7]. Iron (Fe) [7,8], nickel (Ni) [2,7,9], cobalt (Co) [7,8,[10][11][12][13] and copper (Cu) [7,14,15] have been investigated for this purpose. The main challenge associated with using base metals is the phase dependency of their activity and selectivity, i.e., the metal oxide phase typically favors the oxidation of CO, while the metallic phase often favors CO hydrogenation to produce methane (CH 4 ) [11,16,17].…”

Section: Introductionmentioning

confidence: 99%

Magnesium as a Methanation Suppressor for Iron- and Cobalt-Based Oxide Catalysts during the Preferential Oxidation of Carbon Monoxide

2022

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The preferential oxidation of CO (CO-PrOx) to CO2 is an effective catalytic process for purifying the H2 utilized in proton-exchange membrane fuel cells for power generation. Our current work reports on the synthesis, characterization and CO-PrOx performance evaluation of unsubstituted and magnesium-substituted iron- and cobalt-based oxide catalysts (i.e., Fe3O4, Co3O4, MgFe2O4 and MgCo2O4). More specifically, the ability of Mg to stabilize the MgFe2O4 and MgCo2O4 structures, as well as suppress CH4 formation during CO-PrOx was of great importance in this study. The cobalt-based oxide catalysts achieved higher CO2 yields than the iron-based oxide catalysts below 225 °C. The highest CO2 yield (100%) was achieved over Co3O4 between 150 and 175 °C, however, undesired CH4 formation was only observed over this catalyst due to the formation of bulk fcc and hcp Co0 between 200 and 250 °C. The presence of Mg in MgCo2O4 suppressed CH4 formation, with the catalyst only reducing to a CoO-type phase (possibly containing Mg). The iron-based oxide catalysts did not undergo bulk reduction and did not produce CH4 under reaction conditions. In conclusion, our study has demonstrated the beneficial effect of Mg in stabilizing the active iron- and cobalt-based oxide structures, and in suppressing CH4 formation during CO-PrOx.

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Section: Introductionmentioning

confidence: 99%

Magnesium as a Methanation Suppressor for Iron- and Cobalt-Based Oxide Catalysts during the Preferential Oxidation of Carbon Monoxide

2022

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“…Metal oxides of copper (Cu), − nickel (Ni), ,, and cobalt (Co) ,− have become attractive for CO-PrOx as cheap alternative catalysts. Some studies have shown almost similar catalytic performances of these base metal oxides when compared with noble metals.…”

Section: Introductionmentioning

confidence: 99%

“…However, the metal oxides tend to reduce to their metallic state under the H 2 -rich environment of CO-PrOx. In the case of metallic Ni and Co, the conversion pathway of CO changes from oxidation to hydrogenation (eq ), forming CH 4 as a result. ,,− Although CH 4 formation also decreases the CO concentration, this is done at the expense of the valuable H 2 gas required for power generation in PEMFCs, and therefore, it is not desirable. …”

Section: Introductionmentioning

confidence: 99%

“…1−5 If H 2 (40− 75%) is required in proton-exchange membrane fuel cells (PEMFCs) for power generation, the CO concentration needs to be less than 10 ppm (corresponding to a CO conversion to CO 2 of at least 99.999%) to minimize the extent of deactivation of the platinum-based anode catalyst of the PEMFC. 1 Metal oxides of copper (Cu), 6−9 nickel (Ni), 6,10,11 and cobalt (Co) 6,12−17 compared with noble metals. However, the metal oxides tend to reduce to their metallic state under the H 2 -rich environment of CO-PrOx.…”

Section: Introductionmentioning

confidence: 99%

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Environment-Dependent Catalytic Performance and Phase Stability of Co₃O₄in the Preferential Oxidation of Carbon Monoxide StudiedIn Situ

et al. 2020

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The preferential oxidation of CO (CO-PrOx) with co-fed O2 is an attractive route for removing trace amounts of CO in the H2-rich reformate gas prior to being used for power generation in proton-exchange membrane fuel cells. Despite being an affordable and very promising catalyst for CO-PrOx, the CO oxidation activity, selectivity, and phase stability of cobalt(II,III) oxide (Co3O4) may be affected by the other gas feed components, viz., H2, H2O, and CO2. However, the influence of these gases (individually and collectively) during CO-PrOx is still not understood. In the current study, in situ powder X-ray diffraction and magnetometry were used to systematically evaluate unsupported Co3O4 nanoparticles under different CO-PrOx environments, that is, with/without H2, H2O, and/or CO2. The presence of H2 in the feed (with no H2O and CO2) results in the unwanted competitive conversion of the co-fed O2 to H2O and in the reduction of Co3O4 to Co0. The presence of Co0 favors CH4 formation from CO, which is also undesired as it consumes valuable H2. Co-feeding H2O not only decreases Co3O4 reducibility but also decreases CO oxidation activity through competitive surface adsorption. The forward water−gas shift is possible in the absence of CO2 in the feed over CoO and Co0 at elevated reaction temperatures. Co-feeding CO2 has no effect on Co3O4 reducibility but leads to the unwanted CO2 methanation and reverse water−gas shift over Co0. For the first time, the presented work shows the individual and combined effect of H2, H2O, and CO2 on the progress of the targeted CO oxidation process through the occurrence of undesired side reactions. Also, for the first time, in situ catalyst characterization reveals the Co-based phase(s) responsible for the occurrence of each identified side reaction.

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“…CO methanation in the presence of different amounts of CO 2 is a well-known process for purifying H 2 streams from low CO contents (as, for example, purification of H 2 for NH 3 production or for Fuel Cells applications). Several publications regarding the selective methanation of CO in CO 2 -rich reformate gas streams over NiO-CeO 2 systems also exist [19][20][21][22][23][24]. However, to the best of the present authors knowledge, only few papers [25][26][27][28][29][30][31][32][33][34][35][36] about CO and CO 2 co-methanation for SNG production have been published so far, among which five deal with catalysts based on Ni supported on CeO 2 -containing carriers [29,30,32,35,36].…”

Section: Introductionmentioning

confidence: 99%

Characterization and catalytic activity of soft-templated NiO-CeO2 mixed oxides for CO and CO2 co-methanation

Atzori

Cutrufello

Meloni

et al. 2020

Front. Chem. Sci. Eng.

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Nanosized NiO, CeO 2 and NiO-CeO 2 mixed oxides with different Ni/Ce molar ratios were prepared by the soft template method. All the samples were characterized by different techniques as to their chemical composition, structure, morphology and texture. On the catalysts submitted to the same reduction pretreatment adopted for the activity tests the surface basic properties and specific metal surface area were also determined. NiO and CeO 2 nanocrystals of about 4 nm in size were obtained, regardless of the Ni/Ce molar ratio. The Raman and X-ray photoelectron spectroscopy results proved the formation of defective sites at the NiO-CeO 2 interface, where Ni species are in strong interaction with the support. The microcalorimetric and Fourier transform infrared analyses of the reduced samples highlighted that, unlike metallic nickel, CeO 2 is able to effectively adsorb CO 2 , forming carbonates and hydrogen carbonates. After reduction in H 2 at 400°C for 1 h, the catalytic performance was studied in the CO and CO 2 co-methanation reaction. Catalytic tests were performed at atmospheric pressure and 300°C, using CO/CO 2 /H 2 molar compositions of 1/1/7 or 1/1/5, and space velocities equal to 72000 or 450000 cm 3 •h-1 •g cat-1. Whereas CO was almost completely hydrogenated in any investigated experimental conditions, CO 2 conversion was strongly affected by both the CO/CO 2 /H 2 ratio and the space velocity. The faster and definitely preferred CO hydrogenation was explained in the light of the different mechanisms of CO and CO 2 methanation. On a selected sample, the influence of the reaction temperature and of a higher number of space velocity values, as well as the stability, were also studied. Provided that the Ni content is optimized, the NiCe system investigated was very promising, being highly active for the CO x co-methanation reaction in a wide range of operating conditions and stable (up to 50 h) also when submitted to thermal stress. Keywords soft template method, NiO-CeO 2 catalysts, CO and CO 2 co-methanation, synthetic natural gas production

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Preferential oxidation of CO on Ni/CeO2 catalysts in the presence of excess H2 and CO2

Cited by 14 publications

References 43 publications

Magnesium as a Methanation Suppressor for Iron- and Cobalt-Based Oxide Catalysts during the Preferential Oxidation of Carbon Monoxide

Magnesium as a Methanation Suppressor for Iron- and Cobalt-Based Oxide Catalysts during the Preferential Oxidation of Carbon Monoxide

Environment-Dependent Catalytic Performance and Phase Stability of Co₃O₄in the Preferential Oxidation of Carbon Monoxide StudiedIn Situ

Characterization and catalytic activity of soft-templated NiO-CeO2 mixed oxides for CO and CO2 co-methanation

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Preferential oxidation of CO on Ni/CeO2 catalysts in the presence of excess H2 and CO2

Cited by 14 publications

References 43 publications

Magnesium as a Methanation Suppressor for Iron- and Cobalt-Based Oxide Catalysts during the Preferential Oxidation of Carbon Monoxide

Magnesium as a Methanation Suppressor for Iron- and Cobalt-Based Oxide Catalysts during the Preferential Oxidation of Carbon Monoxide

Environment-Dependent Catalytic Performance and Phase Stability of Co3O4in the Preferential Oxidation of Carbon Monoxide StudiedIn Situ

Characterization and catalytic activity of soft-templated NiO-CeO2 mixed oxides for CO and CO2 co-methanation

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Environment-Dependent Catalytic Performance and Phase Stability of Co₃O₄in the Preferential Oxidation of Carbon Monoxide StudiedIn Situ