Effect of Mg addition on the catalytic performance of V-based catalysts in oxidative dehydrogenation of propane

Machli, Maria; Heracleous, Eleni; Lemonidou, Angeliki A.

doi:10.1016/s0926-860x(02)00298-3

Cited by 45 publications

(25 citation statements)

References 39 publications

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“…Strong acid sites, although not present in the samples under study, can be related to strongly bound ammonia on the catalytic surface, leading at high temperatures to decomposition products [30]. The presence of both Lewis and Brønsted acid sites in vanadia-titania system has been stated in our previous study [14]. However, the differences observed between the previous and the present study may be attributed to the different probe molecules and the experimental conditions used.…”

Section: Temperature Programmed Desorption Of Ammoniamentioning

confidence: 40%

“…Our recent studies in oxidative dehydrogenation of propane over vanadia on titania catalyst showed that incorporation of Mg in the vanadia catalyst while beneficial for the selectivity, had a detrimental effect on the conversion [14]. The activity of vanadia catalysts promoted with different amounts of MgO (1.9-10 wt%) as a function of temperature is shown in figure 4.…”

Section: Effect Of Mg Loadingmentioning

confidence: 99%

“…V 2 O 5 on TiO 2 is a very active catalyst in the oxidative dehydrogenation of propane; however, the selectivity to desired product is relatively low. In a previous study we studied the effect of MgO addition (10 wt%) to the catalytic properties of 5 wt% V 2 O 5 on TiO 2 in propane oxidative dehydrogenation [14]. We found that Mg addition results in a significant increase in propene selectivity.…”

Section: Introductionmentioning

confidence: 97%

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Optimization of V2O5?MgO/TiO2 catalyst for the oxidative dehydrogenation of propane effect of magnesia loading and preparation procedure

Machli

Lemonidou

2005

Catal Lett

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The effect of magnesia loading and preparation procedure of vanadia on titania catalysts on the physico-chemical characteristics and the performance in propane oxidative dehydrogenation were investigated. A series of magnesia promoted vanadia catalyst (5 wt% V 2 O 5 ) with varying amounts of MgO (1.9-10 wt%) were synthesized by synchronous and sequential deposition on titania support. The catalysts were characterized using several techniques (BET, XRD, H 2 -TPR and NH 3 -TPD). Both MgO loading and preparation procedure affect the catalyst surface properties and the behavior in the oxidative dehydrogenation of propane. Magnesia addition results in drastic increase in propene selectivity, while the effect on activity is negative. The activity is inversely related with the magnesia loading. Deposition of V 2 O 5 on previously prepared MgO/TiO 2 presents a beneficial effect in the activity of the sample. The role of acidity and reducibility is explored. There is no correlation between reducibility and activity of the catalysts, whereas the acidity seems to influence the catalytic performance. Catalyst containing 5 wt% V 2 O 5 and 1.9 wt% MgO prepared by sequential deposition of V 2 O 5 on already doped with MgO titania exhibits the most interesting results.

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Section: Temperature Programmed Desorption Of Ammoniamentioning

confidence: 40%

Section: Effect Of Mg Loadingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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Optimization of V2O5?MgO/TiO2 catalyst for the oxidative dehydrogenation of propane effect of magnesia loading and preparation procedure

Machli

Lemonidou

2005

Catal Lett

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“…Addition of an appropriate amount of magnesia (Mg/Al = 0.1) to alumina support enhances the stability of Sb-V-O catalysts for the dehydrogenation reaction of ethylbenzene into styrene [33]. This is attributed to the rapid desorption of styrene from MgAl oxide support compared to that of alumina, facilitating desorption of olefins from the catalyst surface which could minimize the carbon accumulation [34,35] and coke formation. It was demonstrated that a high amount of Mg leads to the formation of magnesium vanadate(s) responsible of a decrease of exposed active V-species and diminishes conversion values [31].…”

Section: Introductionmentioning

confidence: 99%

Effect of Mg in Alumina-Supported Sb–V–O Catalysts for the Ammoxidation of Propane into Acrylonitrile

et al. 2008

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The effect of Mg as dopant on alumina-supported mixed Sb-V oxide catalysts during the ammoxidation of propane reaction is evaluated. The Mg-doped catalyst increases acrylonitrile selectivity compared to the un-doped Sb-V-O/Al 2 O 3 system. The presence of magnesium facilitates the formation of a cationic vacancies enriched rutile VSbO 4 phase, involved in C-N triple bond formation. In addition, Mg increases isolation of V 5+ structural site isolation, which may affect selectivity.

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“…[1][2][3] Several families of the catalysts, mainly based on supported or mixed oxides of Fe, V, or Cr were found to be active and selective in the CO 2 -EBDH. [2][3][4][5][6][7][8][9][10][11][12][13][14] However, most of the catalysts have usually shown strong deactivation for this reaction during even a few hours on stream. As a typical example, over Mg-Al-V mixed oxides, the initial styrene yield, 64% after 1 h on stream, decreased to 40% after 7 h. 7 The similar deactivation rate was observed also for VO x /MgO catalyst.…”

mentioning

confidence: 99%

Dehydrogenation of Ethylbenzene with Carbon Dioxide as Oxidant over Mg-modified Alumina-supported V–Sb Oxide Catalysts

Hong¹,

Chang²,

Vislovskiy³

et al. 2005

Chemistry Letters

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Modification of alumina support with an appropriate amount of magnesia (Mg/Al ¼ 0:1) leads to the stable activity of the supported vanadium-antimony oxide catalyst for the dehydrogenation of ethylbenzene into styrene in the presence of carbon dioxide as oxidant. Correlation between catalytic performance and surface acidity has been found.Catalytic dehydrogenation of ethylbenzene in the presence of carbon dioxide (CO 2 -EBDH) has recently been attempted to explore a new technology for producing styrene selectively because it could provide us with an energy-saving and environmentally friendly process to utilize CO 2 , a greenhouse gas, as a mild oxidant.1-3 Several families of the catalysts, mainly based on supported or mixed oxides of Fe, V, or Cr were found to be active and selective in the CO 2 -EBDH.2-14 However, most of the catalysts have usually shown strong deactivation for this reaction during even a few hours on stream. As a typical example, over Mg-Al-V mixed oxides, the initial styrene yield, 64% after 1 h on stream, decreased to 40% after 7 h. 7 The similar deactivation rate was observed also for VO x /MgO catalyst. 3 We have proposed a very active and selective catalyst, V 0:43 Sb 0:57 O x / Al 2 O 3 (VSb/Al), but its deactivation was also significant mainly owing to coke formation although the deactivation rate was less than other reported catalysts. 12,13 Since the coke precursors are easily formed through the oligomerization of olefins, facilitation of olefins desorption from a catalyst surface could minimize the carbon accumulation. Taking into consideration a basic character of electron-rich olefins including styrene, lower surface acidity of the catalyst appears to induce easier desorption of olefins from the catalyst surface. VO x catalysts loaded on MgAl oxide support exhibited a decreased adsorption and rapid desorption of propylene as compared with those on alumina.14,15 Based on these considerations, an attempt has been made to stabilize the activity of VSb/ Al catalyst in the CO 2 -EBDH by the modification of the alumina support with a basic MgO component.MgO-modified alumina (Mg n Al) supports were obtained by impregnation of an activated alumina with aqueous solutions containing a certain amount of Mg(NO 3 ) 2 . 6H 2 O (Mg n Al; n is an atomic ratio of Mg/Al ¼ 0:1, 0.3, or 0.5) followed by calcination at 670 C. Alumina (Al)-or Mg n Al-supported vanadiumantimony oxide catalysts were prepared by impregnation with the solutions of NH 4 VO 3 and SbCl 3 followed by calcination at 650 C. The loading of the supported V 0:43 Sb 0:57 O x component (20 wt %) was the same for all samples. The catalyst supports and supported catalysts were characterized by BET specific surface area (S BET ) measurements (Micrometrics model ASAP 2400), X-ray diffraction (XRD) (Rigaku D/MAX-3B diffractometer) and the NH 3 -temperature-programmed-desorption method (NH 3 -TPD) (Micrometrics, TPD/TPR 027 Option). The catalytic tests were performed with 1 g of catalyst at 595 C under atmospheric pressure in an isothermal ...

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Effect of Mg addition on the catalytic performance of V-based catalysts in oxidative dehydrogenation of propane

Cited by 45 publications

References 39 publications

Optimization of V2O5?MgO/TiO2 catalyst for the oxidative dehydrogenation of propane effect of magnesia loading and preparation procedure

Optimization of V2O5?MgO/TiO2 catalyst for the oxidative dehydrogenation of propane effect of magnesia loading and preparation procedure

Effect of Mg in Alumina-Supported Sb–V–O Catalysts for the Ammoxidation of Propane into Acrylonitrile

Dehydrogenation of Ethylbenzene with Carbon Dioxide as Oxidant over Mg-modified Alumina-supported V–Sb Oxide Catalysts

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