Effect of Ga addition to Pt/Al2O3 on the activity, selectivity and deactivation in the propane dehydrogenation

Jablonski, E.L.; Castro, Alberto A.; Scelza, Osvaldo A.; Miguel, Sergio R. de

doi:10.1016/s0926-860x(99)00058-7

Cited by 93 publications

(60 citation statements)

References 19 publications

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“…These results are in agreement with those reported by Jablonski et al [10], who found that the PtGa/Al 2 O 3 catalysts showed a slight decrease in the chemisorption capacity after reduction at 300°C and a significant decrease after reduction at 500°C. However, the decreases in such ratios were also significant for the lower reduction temperature (350°C), about 49% and 87% in the H/Pt ratio and 55% and 92% in the CO/Pt ratio for the Pt13GaAl and PtGa catalysts, respectively, compared to the values of these ratios in the PtAl catalyst.…”

Section: Dispersion Of Platinumsupporting

confidence: 93%

“…Other catalytic systems, such as Ir/TiO 2 catalysts, have presented the encapsulation of the metal particles by the support after high temperature reduction [21]. Additionally, other authors have found that electronic modifications of Pt sites by Ga could occur in a minor extension when the catalysts were reduced at higher temperatures (773 K) [10]. We do not rule out this explanation.…”

Section: Dispersion Of Platinummentioning

confidence: 65%

“…However, the decreases in such ratios were also significant for the lower reduction temperature (350°C), about 49% and 87% in the H/Pt ratio and 55% and 92% in the CO/Pt ratio for the Pt13GaAl and PtGa catalysts, respectively, compared to the values of these ratios in the PtAl catalyst. Therefore, this decrease in dispersion associated to the addition of gallia can attribute to an intimate contact between Pt particles and partially reduced gallium species formed during the reduction treatment, where these species could encapsulate or block Pt particles [10,[16][17][18].…”

Section: Dispersion Of Platinummentioning

confidence: 99%

“…Owing to the partial reduction of gallia dispersed on a support and the modification of alumina acidity by gallia, it is expected that the presence of gallium can also modify the catalytic properties of a supported metal in different ways depending on the treatment conditions [10]. For this reason, the aim of this work was to study the effect of gallia addition on dispersion and activity of Pt/Al 2 O 3 catalysts for the ethylene hydrogenation reaction as a function of the reduction temperature.…”

Section: Introductionmentioning

confidence: 99%

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Ethylene Hydrogenation over Pt/Ga2O3/Al2O3 Catalysts

et al. 2008

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The effects of gallia addition on the Pt dispersion and the activity for ethylene hydrogenation at 0°C were studied for Pt-supported catalysts as a function of the reduction temperature (350, 450, and 550°C). The catalysts contained 0.5 wt.% Pt and were prepared by successive incipient wetness impregnations with Ga(NO 3 ) 3 and H 2 PtCl 6 aqueous solutions. CO and H 2 chemisorption data indicated that, the addition of small amount of Ga 2 O 3 caused an increase of the Pt dispersion and a decrease of ethylene conversion. Both of them decreased appreciably when Ga 2 O 3 addition was increased, particularly, for the case where bGa 2 O 3 was used as a support. The increase in reduction temperature magnified the negative effects of the gallia addition on dispersion and activity, although the addition of small amount of gallia improved the resistance to metal sintering. Results were interpreted in terms of the presence of reduced Ga species, which can encapsulate Pt particles.

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Section: Dispersion Of Platinumsupporting

confidence: 93%

Section: Dispersion Of Platinummentioning

confidence: 65%

Section: Dispersion Of Platinummentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Ethylene Hydrogenation over Pt/Ga2O3/Al2O3 Catalysts

et al. 2008

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“…[1][2][3][4][5][6]. One important difference between naphtha reforming and dehydrogenation catalysts is related to their acidic character.…”

Section: Introductionmentioning

confidence: 99%

Characterization and Catalytic Performance of PtSn Catalysts Supported on Al2O3 and Na-doped Al2O3 in n-butane Dehydrogenation

et al. 2007

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PtSn/Al 2 O 3 and PtSn/Al 2 O 3 -Na catalysts display important modifications of the metallic phase with respect to Pt/Al 2 O 3 one. In this sense, TPR and XPS results show the presence of strong interactions between Pt and Sn, with probable alloy formation, which would be responsible for the decrease of the reaction rate and the increase of the activation energy in cyclohexane dehydrogenation. Besides the experiments of cyclopentane hydrogenolysis show that the alkali metal addition to bimetallic PtSn/Al 2 O 3 catalysts completely eliminates the hydrogenolytic ensembles, which could be due to a geometric modification of the metallic phase. These important modifications in the nature of the metallic function due to the simultaneous addition of Na and Sn to Pt/Al 2 O 3 are responsible for the excellent catalytic performance in the n-butane dehydrogenation, thus giving high conversions, selectivities to butenes higher than 95%, and lower deactivation capacity than those corresponding to bimetallic PtSn catalysts (with different Sn contents) supported on undoped alumina. The excellent stability of PtSn/Al 2 O 3 -Na catalysts would be due to a low carbon formation during the reaction, such as it was observed from pulse experiments.

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Highly selective and stable multimetallic catalysts for propane dehydrogenation

Miguel

Jablonski

Castro

et al. 2000

J. Chem. Technol. Biotechnol.

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Different mono (Pt), bi (Pt±Sn, Pt±Pb, Pt±Ga) and trimetallic (Pt±Sn±Ga) catalysts based on Pt and supported on different materials (Al 2 O 3 , Al 2 O 3 ±K and ZnAl 2 O 4 ) were tested under severe process conditions in the propane dehydrogenation reaction (both in continuous and in pulse reactors). Results show that the Pt±Sn±Ga/ZnAl 2 O 4 catalyst has a better and more stable performance in propane dehydrogenation (high yield to propene and low coke deposition), than the other bi-and trimetallic systems and a commercial catalyst. Thus, the use of an adequate support (ZnAl 2 O 4 ) in combination with the addition of Ga to the Pt±Sn bimetallic system enhances the catalytic performance. INTRODUCTIONThe selective propane dehydrogenation to propene is a very important industrial process since it produces a valuable raw material for polypropene manufacture. This process can be carried out by using supported metallic catalysts, though several dif®culties should be avoided in order to develop catalysts with a good performance. In this sense, both the inhibition of hydrogenolysis and cracking reactions, and the minimisation of the coke deposition, are major requirements in order to increase the selectivity to propene and the catalytic stability. From the development of the STAR Process, 1 different bimetallic supported systems have been studied in this reaction. The utilisation of non-acidic and thermal stable supports, such as MgAl 2 O 4 or ZnAl 2 O 4 , 2±4 appears as an important factor in order to increase the stability of the metallic phase during successive operational cycles. Besides, the addition of Sn to Pt improves alkene formation and reduces coke deposition. 5 Hence, both the selection of an adequate support and the composition of the metallic phase can be considered as relevant factors in order to develop better catalysts for this process.In this paper, the behaviour of different catalysts (Pt, Pt±Sn, Pt±Ga, Pt±Pb and Pt±Sn±Ga supported on Al 2 O 3 , K±Al 2 O 3 and ZnAl 2 O 4 ) in the propane dehydrogenation reaction are compared with a commercial catalyst used for dehydrogenation of alkanes on an industrial scale. The effects of the three different supports and the addition of several inactive metals of

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Effect of Ga addition to Pt/Al2O3 on the activity, selectivity and deactivation in the propane dehydrogenation

Cited by 93 publications

References 19 publications

Ethylene Hydrogenation over Pt/Ga2O3/Al2O3 Catalysts

Ethylene Hydrogenation over Pt/Ga2O3/Al2O3 Catalysts

Characterization and Catalytic Performance of PtSn Catalysts Supported on Al2O3 and Na-doped Al2O3 in n-butane Dehydrogenation

Highly selective and stable multimetallic catalysts for propane dehydrogenation

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