Catalytic oxidations with sulfur dioxide II. Alkylaromatics

Adams, Charles R.; Jennings, Tina

doi:10.1016/0021-9517(70)90089-8

Cited by 34 publications

(6 citation statements)

References 4 publications

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“…Interestingly, the oxidant used in the ODH reaction also plays a crucial role in determining the activity, selectivity, and stability of the catalysts. The use of O 2 , CO 2 , SO 2 , N 2 , dry air, and N 2 O gases as oxidants has been investigated for the ODH processes. ,,,, The application of O 2 and SO 2 leads to deep oxidation of ethylbenzene to CO x and the formation of toxic side products, respectively . CO 2 as an oxidant is believed to result in the formation of carbonaceous deposits resulting in fast deactivation of the catalyst, and N 2 O leads to more styrene oxide selectivity …”

Section: Resultsmentioning

confidence: 99%

Structural Characterization and Oxidehydrogenation Activity of CeO₂/Al₂O₃and V₂O₅/CeO₂/Al₂O₃Catalysts

et al. 2007

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Structural characterization and oxidative dehydrogenation activity of CeO 2 /Al 2 O 3 and V 2 O 5 /CeO 2 /Al 2 O 3 catalysts for ethylbenzene (EB) to styrene were investigated systematically. The CeO 2 /Al 2 O 3 catalyst was prepared by a deposition precipitation method, and a theoretical monolayer equivalent of 10 wt % V 2 O 5 was dispersed over its surface by a wet impregnation method to obtain the V 2 O 5 /CeO 2 /Al 2 O 3 catalyst. To understand thermal and textural stability, the synthesized catalysts were subjected to calcination at various temperatures (773-1073 K). Physicochemical characterization was performed using X-ray diffraction (XRD), Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, and BET surface area techniques. The XRD and RS results suggested that the CeO 2 /Al 2 O 3 sample is thermally quite stable up to 1073 K and that the ceria exists in the form of an over layer on the surface of the alumina support. In the case of the V 2 O 5 /CeO 2 /Al 2 O 3 sample, no crystalline V 2 O 5 was observed from XRD results, indicating a highly dispersed form of vanadium oxide on the CeO 2 /Al 2 O 3 carrier when calcined at 773 K. The XPS peak shapes and the corresponding electron binding energies indicate that the dispersed vanadium oxide selectively interacts with the ceria portion of the CeO 2 /Al 2 O 3 support and forms a CeVO 4 compound at higher calcination temperatures. Formation of CeVO 4 is also established from XRD and RS measurements. Both CeO 2 /Al 2 O 3 and V 2 O 5 /CeO 2 / Al 2 O 3 samples were tested for oxidative dehydrogenation of EB to styrene by using dry air as an oxidant. The V 2 O 5 /CeO 2 /Al 2 O 3 catalyst exhibits more conversion and selectivity than CeO 2 /Al 2 O 3 . The time-on-stream experiments further reveal that the V 2 O 5 /CeO 2 /Al 2 O 3 catalyst exhibits stable activity and selectivity without fast deactivation.

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Section: Resultsmentioning

confidence: 99%

Structural Characterization and Oxidehydrogenation Activity of CeO₂/Al₂O₃and V₂O₅/CeO₂/Al₂O₃Catalysts

et al. 2007

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“…The use of O 2 , CO 2 , SO 2 , N 2 , dry air, and N 2 O gases as oxidants has been investigated for the ODH processes. The application of O 2 and SO 2 leads to deep oxidation of ethylbenzene to CO x and the formation of toxic side products, respectively . CO 2 as an oxidant results in the formation of carbonaceous deposits resulting in fast deactivation of the catalyst, and N 2 O leads to more styrene oxide selectivity .…”

Section: Resultsmentioning

confidence: 99%

Structural Characterization and Oxidative Dehydrogenation Activity of V₂O₅/Ce_xZr_1-_xO₂/SiO₂ Catalysts

et al. 2006

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The thermal stability of a nanosized Ce(x)Zr(1-x)O2 solid solution on a silica surface and the dispersion behavior of V2O5 over Ce(x)Zr(1-x)O2/SiO2 have been investigated using XRD, Raman spectroscopy, XPS, HREM, and BET surface area techniques. Oxidative dehydrogenation of ethylbenzene to styrene was performed as a test reaction to assess the usefulness of the VOx/Ce(x)Zr(1-x)O2/SiO2 catalyst. Ce(x)Zr(1-x)O2/SiO2 (1:1:2 mol ratio based on oxides) was synthesized through a soft-chemical route from ultrahigh dilute solutions by adopting a deposition coprecipitation technique. A theoretical monolayer equivalent to 10 wt % V2O5 was impregnated over the calcined Ce(x)Zr(1-x)O2/SiO2 sample (773 K) by an aqueous wet impregnation technique. The prepared V2O5/Ce(x)Zr(1-x)O2/SiO2 sample was subjected to thermal treatments from 773 to 1073 K. The XRD measurements indicate the presence of cubic Ce0.75Zr0.25O2 in the case of Ce(x)Zr(1-x)O2/SiO2, while cubic Ce0.5Zr0.5O2 and tetragonal Ce0.16Zr0.84O2 in the case of V2O5/Ce(x)Zr(1-x)O2/SiO2 when calcined at various temperatures. Dispersed vanadium oxide induces more incorporation of zirconium into the ceria lattice, thereby decreasing its lattice size and also accelerating the crystallization of Ce-Zr-O solid solutions at higher calcination temperatures. Further, it interacts selectively with the ceria portion of the composite oxide to form CeVO4. The RS measurements provide good evidence about the dispersed form of vanadium oxide and the CeVO4 compound. The HREM studies show the presence of small Ce-Zr-oxide particles of approximately 5 nm size over the surface of amorphous silica and corroborate with the results obtained from other techniques. The catalytic activity studies reveal the ability of vanadium oxide supported on Ce(x)Zr(1-x)O2/SiO2 to efficiently catalyze the ODH of ethylbenzene at normal atmospheric pressure. The remarkable ability of Ce(x)Zr(1-x)O2 to prevent the deactivation of supported vanadium oxide leading to stable activity in the time-on-stream experiments and high selectivity to styrene are other important observations.

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“…Various methods have been attempted to solve the above-mentioned problems of using steam during the dehydrogenation of ethylbenzene. The oxidative dehydrogenation (ODH) process of ethylbenzene to styrene in the presence of oxidant has attracted considerable attention because it can be operated at lower temperatures and ethylbenzene conversion would not be equilibrium limited. , A variety of oxidizing agents, such as O 2 , N 2 O, SO 2 and CO 2 , have been used for the oxidative dehydrogenation of ethylbenzene to lower the reaction temperature. ,− Exploitation of CO 2 as a soft oxidant for the commercial catalytic ODH of ethylbenzene to styrene has received enormous interest recently because of several benefits of using CO 2 compared with other oxidants. It has been reported that CO 2 can act as a soft oxidant as well as diluent .…”

Section: Introductionmentioning

confidence: 99%

Role Of CO₂ As a Soft Oxidant For Dehydrogenation of Ethylbenzene to Styrene over a High-Surface-Area Ceria Catalyst

Zhang¹,

Wu²,

Nelson

et al. 2015

ACS Catal.

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Catalytic performance and the nature of surface adsorbates were investigated for high-surface-area ceria during the ethylbenzene oxidative dehydrogenation (ODH) reaction using CO2 as a soft oxidant. The high surface area ceria material was synthesized using a template-assisted method. The interactions among ethylbenzene, styrene, and CO2 on the surface of ceria and the role of CO2 for the ethylbenzene ODH reaction have been investigated in detail by using activity test, in situ diffuse reflectance infrared and Raman spectroscopy. CO2 as an oxidant not only favored the higher yield of styrene but also inhibited the deposition of coke during the ethylbenzene ODH reaction. Ethylbenzene ODH reaction over ceria followed a two-step pathway: ethylbenzene is first dehydrogenated to styrene with H2 formed simultaneously, and then CO2 reacts with H2 via the reverse water gas shift. The produced styrene can easily undergo polymerization to form polystyrene, which is a key intermediate for coke formation. In the absence of CO2, the produced polystyrene transforms into graphite-like coke at temperatures above 500 °C, which leads to catalyst deactivation. In the presence of CO2, the coke deposition can be effectively removed via oxidation with CO2. ABSTRACT: Catalytic performance and the nature of surface adsorbates were investigated for high-surface-area ceria during the ethylbenzene oxidative dehydrogenation (ODH) reaction using CO 2 as a soft oxidant. The high surface area ceria material was synthesized using a template-assisted method. The interactions among ethylbenzene, styrene, and CO 2 on the surface of ceria and the role of CO 2 for the ethylbenzene ODH reaction have been investigated in detail by using activity test, in situ diffuse reflectance infrared and Raman spectroscopy. CO 2 as an oxidant not only favored the higher yield of styrene but also inhibited the deposition of coke during the ethylbenzene ODH reaction. Ethylbenzene ODH reaction over ceria followed a two-step pathway: ethylbenzene is first dehydrogenated to styrene with H 2 formed simultaneously, and then CO 2 reacts with H 2 via the reverse water gas shift. The produced styrene can easily undergo polymerization to form polystyrene, which is a key intermediate for coke formation. In the absence of CO 2 , the produced polystyrene transforms into graphite-like coke at temperatures above 500°C, which leads to catalyst deactivation. In the presence of CO 2 , the coke deposition can be effectively removed via oxidation with CO 2 .

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Catalytic oxidations with sulfur dioxide II. Alkylaromatics

Cited by 34 publications

References 4 publications

Structural Characterization and Oxidehydrogenation Activity of CeO₂/Al₂O₃and V₂O₅/CeO₂/Al₂O₃Catalysts

Structural Characterization and Oxidehydrogenation Activity of CeO₂/Al₂O₃and V₂O₅/CeO₂/Al₂O₃Catalysts

Structural Characterization and Oxidative Dehydrogenation Activity of V₂O₅/Ce_xZr_1-_xO₂/SiO₂ Catalysts

Role Of CO₂ As a Soft Oxidant For Dehydrogenation of Ethylbenzene to Styrene over a High-Surface-Area Ceria Catalyst

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Catalytic oxidations with sulfur dioxide II. Alkylaromatics

Cited by 34 publications

References 4 publications

Structural Characterization and Oxidehydrogenation Activity of CeO2/Al2O3and V2O5/CeO2/Al2O3Catalysts

Structural Characterization and Oxidehydrogenation Activity of CeO2/Al2O3and V2O5/CeO2/Al2O3Catalysts

Structural Characterization and Oxidative Dehydrogenation Activity of V2O5/CexZr1-xO2/SiO2 Catalysts

Role Of CO2 As a Soft Oxidant For Dehydrogenation of Ethylbenzene to Styrene over a High-Surface-Area Ceria Catalyst

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Structural Characterization and Oxidehydrogenation Activity of CeO₂/Al₂O₃and V₂O₅/CeO₂/Al₂O₃Catalysts

Structural Characterization and Oxidehydrogenation Activity of CeO₂/Al₂O₃and V₂O₅/CeO₂/Al₂O₃Catalysts

Structural Characterization and Oxidative Dehydrogenation Activity of V₂O₅/Ce_xZr_1-_xO₂/SiO₂ Catalysts

Role Of CO₂ As a Soft Oxidant For Dehydrogenation of Ethylbenzene to Styrene over a High-Surface-Area Ceria Catalyst