Microkinetics of Water−Gas Shift over Sulfided Mo/Al<sub>2</sub>O<sub>3</sub>Catalysts

Lund, C.R.F.

doi:10.1021/ie950608u

Cited by 48 publications

(28 citation statements)

References 22 publications

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“…A concomitant presence of potassium, nickel, and molybdenum favours the formation of oxysulfide molybdenum species associated with the highest catalytic activity of the tri-component system observed at the lower reaction temperatures. The trend of changes in oxidation (reducibility) and sulfidic (sulfur lability) states of molybdenum related to the catalytic activity of the Mo, KMo, NiMo, and KNiMo systems points to a regenerative (redox) mechanism of the WGS reaction taking place in the case of sulfided Mo [33,34] and Co-Mo catalysts [13]. It may be stated that the effect of alkali presence is related to the K ion affinity to (Ni)Mo in forming surface K-(Ni)-Mo-O species.…”

Section: Resultsmentioning

confidence: 99%

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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Section: Resultsmentioning

confidence: 99%

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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“…A microkinetic model for water-gas shift over sulfided Mo/Al 2 O 3 and sulfided CoMo/Al 2 O 3 was developed a few years ago [20,21]. Since the mechanism of the reaction on these catalysts is believed to be very different from that on iron oxide catalysts, it seemed quite possible that the rate would not be inhibited by CO 2 .…”

Section: Resultsmentioning

confidence: 99%

“…The second idealized situation corresponded to a perfect catalyst. In this case, model consisted of only equation (21). The other molar flow rates and the temperature were calculated by assuming that the reaction was always at thermodynamic equilibrium (with a corresponding adiabatic temperature rise).…”

Section: Methodsmentioning

confidence: 99%

Water-Gas Shift Kinetics Over Iron Oxide Catalysts at Membrane Reactor Conditions

Lund¹

2002

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“…A microkinetic model for water-gas shift over sulfided Mo/Al 2 O 3 and sulfided CoMo/Al 2 O 3 was developed a few years ago 4,5 . Since the mechanism of the reaction on these catalysts is believed to be very different from that on iron oxide catalysts, it seemed quite possible that the rate would not be inhibited by CO 2 .…”

Section: Computational Evaluation Of Sulfided Como/al 2 O 3 Catalystsmentioning

confidence: 99%

Water-Gas Shift Kinetics Over Iron Oxide Catalysts at Membrane Reactor Conditions

Lund¹

2001

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This report covers the second year of a project investigating water-gas shift catalysts for use in membrane reactors. It has been established that a simple iron high temperature shift catalyst becomes ineffective in a membrane reactor because the reaction rate is severely inhibited by the build-up of the product CO 2 . During the past year, an improved microkinetic model for water-gas shift over iron oxide was developed. Its principal advantage over prior models is that it displays the correct asymptotic behavior at all temperatures and pressures as the composition approaches equilibrium. This model has been used to explore whether it might be possible to improve the performance of iron high temperature shift catalysts under conditions of high CO 2 partial pressure. The model predicts that weakening the surface oxygen bond strength by less than 5% should lead to higher catalytic activity as well as resistance to rate inhibition at higher CO 2 partial pressures. Two promoted iron high temperature shift catalysts were studied. Ceria and copper were each studied as promoters since there were indications in the literature that they might weaken the surface oxygen bond strength. Ceria was found to be ineffective as a promoter, but preliminary results with copper promoted FeCr high temperature shift catalyst show it to be much more resistant to rate inhibition by high levels of CO 2 . Finally, the performance of sulfided CoMo/Al 2 O 3 catalysts under conditions of high CO 2 partial pressure was simulated using an available microkinetic model for water-gas shift over this catalyst. The model suggests that this catalyst might be quite effective in a medium temperature water-gas shift membrane reactor, provided that the membrane was resistant to the H 2 S that is required in the feed.4

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Microkinetics of Water−Gas Shift over Sulfided Mo/Al₂O₃Catalysts

Cited by 48 publications

References 22 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

Water-Gas Shift Kinetics Over Iron Oxide Catalysts at Membrane Reactor Conditions

Water-Gas Shift Kinetics Over Iron Oxide Catalysts at Membrane Reactor Conditions

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Microkinetics of Water−Gas Shift over Sulfided Mo/Al2O3Catalysts

Cited by 48 publications

References 22 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

Water-Gas Shift Kinetics Over Iron Oxide Catalysts at Membrane Reactor Conditions

Water-Gas Shift Kinetics Over Iron Oxide Catalysts at Membrane Reactor Conditions

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Microkinetics of Water−Gas Shift over Sulfided Mo/Al₂O₃Catalysts