The effect of potassium addition on the state of the components in the oxide precursor of the (Ni)(Mo)/γ-Al2O3 water-gas shift catalysts: FT-IR, diffuse reflectance and Raman spectroscopic studies

Nikolova, D.; Edreva-Kardjieva, R.; Giurginca, Maria; Meghea, Aurelia; Vakros, John; Voyiatzis, George A.; Kordulis, Christos

doi:10.1016/j.vibspec.2007.03.002

Cited by 27 publications

(20 citation statements)

References 40 publications

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“…An attempt was made to correlate the activity results with the nature of the species formed on the oxidic catalyst precursors during the calcination step [28].…”

Section: Resultsmentioning

confidence: 99%

“…ions appear in Oh surrounding associated with the formation of polymolybdate (-MoO 6 -) n structures, i.e. a combination between heptamolybdate [28]. The Mo polymeric species prove to be favored oxidic precursors of the active species in the WGS reaction.…”

Section: Resultsmentioning

confidence: 99%

“…This may be categorically assigned to the formation of surface species, analogous to potassium molybdate (K 2 MoO 4 ) in KMo samples, related to a change from an octahedral to tetrahedral ligand surrounding of the Mo 6? ions [28,31]. The monomeric molybdenum tetrahedral species prove to be unfavorable precursors of the active species in the WGS reaction.…”

Section: Resultsmentioning

confidence: 99%

“…The samples are listed in Table 1. Details of the preparation procedures have been reported elsewhere [28]. (i) Decreasing the reaction temperature in the range of 400(500)-180°C at steam/ gas ratio (s/g) 0.3 and GHSV = 4000 h -1 ; (ii) Varying the steam/gas ratio (s/g = 0.3, 0.7, 1) at 400°C and GHSV = 4000 h -1 .…”

Section: Sample Preparationmentioning

confidence: 99%

“…Introduction of potassium and nickel was found to provoke different kinds of oxidic surface species on calcined precursors by varying the molybdenum content within the range of 1-4 atoms Mo/nm 2 support [28]. These oxidic species are presumed to generate different WGS activity.…”

Section: Introductionmentioning

confidence: 99%

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Water–gas shift activity of K-promoted (Ni)Mo/γ-Al2O3 systems in sulfur-containing feed

Nikolova

Edreva-Kardjieva

Grozeva

2011

Reac Kinet Mech Cat

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The effect of potassium additive on the catalytic activity of nickelmolybdenum alumina-supported systems has been studied by varying the molybdenum content within 5-18 mass% MoO 3 , reaction temperature from 180 to 400 (500)°C, and steam to gas ratio of 0.3, 0.7, and 1. It has been established that potassium reduces the activity of one-component Mo-containing samples, while, independent of molybdenum loading, nickel promotes activity within the whole temperature range studied and extends the temperature range of catalytic activity by about 70°C to lower reaction temperatures. A symbatic or additive, or antibatic catalytic behavior was observed with NiMo-containing samples depending on the atomic Ni/Mo ratio and temperature range. Potassium, being a third component in tri-component KNiMo-containing samples, enhances the water-gas shift (WGS) activity depending on the atomic K/(Ni ? Mo) ratio. The activity approaches the equilibrium conversion degree in the interval of 320-500°C. A decrease in the specific surface area of calcined and tested samples relative to the bare support shows close values indicating that the overall dispersion of the species is not changed during the catalytic test. Close examination indicated that the sample containing K 2 O, NiO, and MoO 3 of 4.9, 2.5, and 12.7 mass%, respectively, was found to be the most suitable catalyst for water-gas shift reaction with sulfur containing feed since it attains equilibrium conversion even at 300°C, and at a low steam to gas ratio of 0.3 atm. This catalyst demonstrates a stable and reproducible catalytic activity as inlet gas loading is increased.

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“…An attempt was made to correlate the activity results with the nature of the species formed on the oxidic catalyst precursors during the calcination step [28].…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Sample Preparationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Water–gas shift activity of K-promoted (Ni)Mo/γ-Al2O3 systems in sulfur-containing feed

Nikolova

Edreva-Kardjieva

Grozeva

2011

Reac Kinet Mech Cat

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Catalytic performance stability of Mo, W and Re-based sour water–gas shift catalysts

Nikolova

Edreva-Kardjieva

Gabrovska

2020

Reac Kinet Mech Cat

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Activity of the Ni–Al Mixed Oxides Prepared from Hydrotalcite-Like Precursors in the Oxidative Dehydrogenation of Ethane and Propane

et al. 2011

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The activity of Ni-Al mixed oxides obtained by the thermal pre-treatment of Ni-Al hydrotalcite-like precursors was studied in the ODH of ethane and propane. The activity of the Ni-Al mixed oxide catalysts was studied with respect to (i) the role of Ni content and (ii) the role of temperature during Ni-Al HTs thermal pre-treatment. The structure analysis and the activity of Ni-Al mixed oxides were discussed in three groups; (A) the catalysts pre-treated at 500°C, (B) the catalysts pre-treated at 600°C and (C) the Ni2-Al catalyst with constant Ni content pre-treated at 500-900°C. Ni-Al mixed oxides were active and selective catalysts in the ODH of ethane even at 450°C. On the other hand, the catalysts posses low selectivity to propene. It is supposed that the interaction of NiO with alumina phase plays the critical role in the active and selective catalysts. The Ni-Al mixed oxides were characterized by XRD, H 2 -TPR and diffuse reflectance spectroscopy.

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The effect of potassium addition on the state of the components in the oxide precursor of the (Ni)(Mo)/γ-Al2O3 water-gas shift catalysts: FT-IR, diffuse reflectance and Raman spectroscopic studies

Cited by 27 publications

References 40 publications

Water–gas shift activity of K-promoted (Ni)Mo/γ-Al2O3 systems in sulfur-containing feed

Water–gas shift activity of K-promoted (Ni)Mo/γ-Al2O3 systems in sulfur-containing feed

Catalytic performance stability of Mo, W and Re-based sour water–gas shift catalysts

Activity of the Ni–Al Mixed Oxides Prepared from Hydrotalcite-Like Precursors in the Oxidative Dehydrogenation of Ethane and Propane

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