Effect of Co/Ni ratios in cobalt nickel mixed oxide catalysts on methane combustion

Lim, Tae Hwan; Cho, Sung June; Yang, Hee Chan; Engelhard, Mark H.; Kim, Do Heui

doi:10.1016/j.apcata.2015.07.040

Cited by 99 publications

(67 citation statements)

References 62 publications

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“…Lim et al. investigated the effect of different components in cobalt–nickel binary catalysts on methane combustion at a relatively low concentration (1500 ppm), but the temperature of complete methane oxidation was above 500 °C . According to the references above, it is expected that cobalt–nickel mixed oxides may be ideal catalysts for lean methane oxidation; however, lowering the temperature for catalytic combustion of methane is still a main issue.…”

Section: Introductionsupporting

confidence: 90%

“…With respect to the pore volume, Co1Ni4 had the smallest pore volume of 0.0821 cm 3 g −1 . When it comes to the average pore size, we found a phenomenon similar to the surface area, that is, the pure single oxides (Co0Ni10, Co10Ni0) have higher average pore size than the cobalt–nickel mixed oxides, indicating that the two pure single oxides have similar physical properties in some respects …”

Section: Resultsmentioning

confidence: 99%

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Low Temperature Complete Combustion of Lean Methane over Cobalt–Nickel Mixed‐Oxide Catalysts

Shao

Lin

et al. 2016

Energy Tech

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Cobalt–nickel mixed oxides with different Co/Ni molar ratios were prepared by co‐precipitation and used for the catalytic combustion of lean methane. The catalytic performances for methane combustion were evaluated at steady‐state conditions at temperatures ranging from 250 to 500 °C, which were increased in step sizes of 25 °C. Among the catalysts, the cobalt–nickel mixed‐oxide catalysts with an appropriate Co/Ni ratio exhibit a high catalytic performance for the lean methane combustion, with the catalyst having a Co/Ni molar ratio of 1:4 showing the highest catalytic activity (methane conversion reached 100 % at 425 °C). On the basis of TEM and XRD results, the nanoparticles of the catalysts have a suitable interparticle spacing and more crystal defects. X‐ray photoelectron spectroscopy (XPS) results reveal a high number of surface‐active oxygen species and appropriate aliovalent cobalt ion numbers in the catalysts for high catalytic activity. All these effects contribute to the outstanding performance of these catalysts in the combustion of lean methane at low temperatures.

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Section: Introductionsupporting

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Low Temperature Complete Combustion of Lean Methane over Cobalt–Nickel Mixed‐Oxide Catalysts

Shao

Lin

et al. 2016

Energy Tech

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“…As shown in Fig. 2a, there were three distinct reduction peaks in NiCo 2 O 4 , and the peaks appeared at 253 and 360 °C, corresponding to the reduction steps of Co 3+ to Co 2+ and Co 2+ to Co 0 , respectively (Gou et al 2013; Lim et al 2015), while the peak appeared at 315 °C, which was attributed to the reduction of Ni 2+ to Ni 0 . However, in comparison to NiCo 2 O 4 , the H 2 -TPR profile of the NiCo 1.95 Pd 0.05 O 4 catalyst showed one slight peak and one strong broad peak.…”

Section: Resultsmentioning

confidence: 99%

Highly selective catalytic reduction of NO via SO2/H2O-tolerant spinel catalysts at low temperature

Cai

Sun

et al. 2016

Environ Sci Pollut Res

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Selective catalytic reduction of NOX by hydrogen (H2-SCR) in the presence of oxygen has been investigated over the NiCo2O4 and Pd-doped NiCo2O4 catalysts under varying conditions. The catalysts were prepared by a sol-gel method in the presence of oxygen within 50–350 °C and were characterized using XRD, BET, EDS, XPS, Raman, H2-TPR, and NH3-TPD analysis. The results demonstrated that the doped Pd could improve the catalyst reducibility and change the surface acidity and redox properties, resulting in a higher catalytic performance. The performance of NiCo1.95Pd0.05O4 was consistently better than that of NiCo2O4 within the 150–350 °C range at a gas hourly space velocity (GHSV) of 4800 mL g−1 h−1, with a feed stream containing 1070 ppm NO, 10,700 ppm H2, 2 % O2, and N2 as balance gas. The effects of GHSV, NO/H2 ratios, and O2 feed concentration on the NO conversion over the NiCo2O4 and NiCo1.95Pd0.05O4 catalysts were also investigated. The two samples similarly showed that an increase in GHSV from 4800 to 9600 mL h−1 g−1, the NO/H2 ratio from 1:10 to 1:1, and the O2 content from 0 to 6 % would result in a decrease in NO conversion. In addition, 2 %, 5 %, and 8 % H2O into the feed gas had a slightly negative influence on SCR activity over the two catalysts. The effect of SO2 on the SCR activity indicated that the NiCo1.95Pd0.05O4 possesses better SO2 tolerance than NiCo2O4 catalyst does.Graphical abstractThe NiCo1.95Pd0.05O4 catalyst achieved over 90 % NO conversion with N2 selectivity of 100 % in the 200∼250 °C range than the maximum 40.5 % NO conversion over NiCo2O4 with N2 selectivity of approximately 80 % in 350 °C.

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“…Materials with exposed (110) planes show enhanced catalytic activity for methane oxidation compared with those only exposing (100) or (111) facets, enabling complete methane conversion below 400 °C (GHSV = 40 000 mL g −1 h −1 ) . Bimetallic NiCo 2 O 4 has been shown to have better catalytic activity than any single metal oxide due to structural disorder, making this a particularly enticing candidate for catalysis, as well as energy conversion and storage applications . The effect of the Ni/Co ratio in nickel cobalt oxides on methane oxidation has been investigated and it was found that distorted NiCo 2 O 4 spinel catalysts show excellent activity with 90% conversion at ≈470 °C (GHSV = 60 000 mL g −1 h −1 ) .…”

Section: Introductionmentioning

confidence: 99%

“…Bimetallic NiCo 2 O 4 has been shown to have better catalytic activity than any single metal oxide due to structural disorder, making this a particularly enticing candidate for catalysis, as well as energy conversion and storage applications . The effect of the Ni/Co ratio in nickel cobalt oxides on methane oxidation has been investigated and it was found that distorted NiCo 2 O 4 spinel catalysts show excellent activity with 90% conversion at ≈470 °C (GHSV = 60 000 mL g −1 h −1 ) . Trivedi et al developed NiCo 2 O 4−δ spinel catalysts by reactive calcination of precursors in a CO‐air environment to expose more active sites.…”

Section: Introductionmentioning

confidence: 99%

Bowtie‐Shaped NiCo₂O₄ Catalysts for Low‐Temperature Methane Combustion

Dai

Kumar

Zhu

et al. 2019

Adv Funct Materials

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Bowtie-shaped NiCo 2 O 4 nanostructures are prepared using a hydrothermal method. Variation of the synthesis parameters, including reaction time, additives, and calcination temperature, allows an understanding of the origin of the bowtie-shaped structure to be developed. Methane oxidation experiments performed using temperature-programed oxidation (TPO) show that the new materials, which do not contain precious metals, have excellent activity for low-temperature methane combustion, with 100% conversion at ≈410 °C (gas hourly space velocity (GHSV): 90 000 mL (STP) g −1 h −1 ). The structure-activity relationships of the bowtie-shaped nanostructures are explored. The relatively low exhaust temperature in NGVs means that the activation of methane, which has the strongest CH bond of any hydrocarbon, is challenging from a chemical perspective. It is not surprising that the quest for effective lowtemperature methane oxidation catalysts has focused mainly on systems involving precious metals, such as platinum and palladium. [11][12][13][14][15] Metal oxidesupported PdO catalysts are generally considered to represent the state of the art for methane combustion catalysts. [16][17][18][19][20] Recent research in this field has focused on improving activity at low temperatures, [21,22] reducing the required loading of metal [23,24] and improving the thermal and hydrothermal stability of PdO catalysts. [25][26][27][28][29][30] Exciting recent advances include the development of core-shell Pd@CeO 2 catalysts with high activity and thermal stability, demonstrating complete conversion to CO 2 below 400 °C (gas hourly space velocity (GHSV) = 200 000 mL g −1 h −1 ). [21] Pd@ZrO 2 /Si-Al 2 O 3 catalysts that are stable in the presence of high concentrations of water vapor have also been proposed recently. [25] NiO@PdO/Al 2 O 3 catalysts that show good activity and stability with only 0.2 wt% Pd loading have been prepared [23] as well as Pd-based bimetallic nanocrystalline catalysts, in which the promotional effects of different transition metals have been examined. [26] Although Pd-based catalysts show excellent activity, the high price and low abundance of palladium are limiting factors to practical application, [31] and both the hydrothermal stability and SO 2 tolerance for these catalysts need to be improved. For this reason, the development of alternative catalysts based on non-noble metals is attractive. [32] These include single metal oxide-based catalysts (CuO, [33] Co 3 O 4 , [34] and MnO 2 [35] ), perovskite, [36,37] spinel, [38,39] and hexaaluminate [40] catalysts. Among these, Co 3 O 4 exhibits good activity for methane combustion attributed to a spinel-type structure with variable Co oxidation states and a high density of oxygen vacancies on the surface. [41] Additionally, the specific exposed facets and morphology of Co 3 O 4 plays an important role in the catalysis. [42,43] Materials with exposed (110) planes show enhanced catalytic activity for methane oxidation compared with those only exposing (100) or (111) face...

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Effect of Co/Ni ratios in cobalt nickel mixed oxide catalysts on methane combustion

Cited by 99 publications

References 62 publications

Low Temperature Complete Combustion of Lean Methane over Cobalt–Nickel Mixed‐Oxide Catalysts

Low Temperature Complete Combustion of Lean Methane over Cobalt–Nickel Mixed‐Oxide Catalysts

Highly selective catalytic reduction of NO via SO2/H2O-tolerant spinel catalysts at low temperature

Bowtie‐Shaped NiCo₂O₄ Catalysts for Low‐Temperature Methane Combustion

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Effect of Co/Ni ratios in cobalt nickel mixed oxide catalysts on methane combustion

Cited by 99 publications

References 62 publications

Low Temperature Complete Combustion of Lean Methane over Cobalt–Nickel Mixed‐Oxide Catalysts

Low Temperature Complete Combustion of Lean Methane over Cobalt–Nickel Mixed‐Oxide Catalysts

Highly selective catalytic reduction of NO via SO2/H2O-tolerant spinel catalysts at low temperature

Bowtie‐Shaped NiCo2O4 Catalysts for Low‐Temperature Methane Combustion

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Bowtie‐Shaped NiCo₂O₄ Catalysts for Low‐Temperature Methane Combustion