Synthesis of solid superacid catalyst with acid strength of H<sub>0</sub>⩽–16.04

Hino, Makoto; Arata, Kazushi

doi:10.1039/c39800000851

Cited by 375 publications

(239 citation statements)

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“…[1] Hino and Arata reported in 1979 and 1980 the isomerisation of nbutane at room temperature on sulfated zirconia. [2,3] Their work initiated a strong interest in the application of this type of material in acid catalysis, [4,5] and commercial use followed. [6] Sulfate is a key component, and numerous propositions of its structure on the zirconia surface have been published, the majority of which were developed with the design of strong Brønsted or Lewis acid sites in mind.…”

Section: Introductionmentioning

confidence: 99%

“…Thin, singlecrystalline films grown on conducting substrates have been successfully employed leading to a detailed knowledge of the surface structure and reactivity of oxides. [10,11] For example, Meinel et al [12] prepared single-crystalline cubic sulfated zirconia films by reactive deposition of zirconium onto Pt(111) in an O 2 atmosphere, followed by exposure to a SO 3 atmosphere. During sulfation a (√3 x √3)R30° structure develops, which is stable to 700 K. The drawbacks of single crystal models are their oversimplifications, for example the lack of defects and support interaction; the transfer of findings to "real" powder catalysts has thus had limited success.…”

Section: Introductionmentioning

confidence: 99%

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Adsorption–desorption equilibrium investigations of n-butane on nanocrystalline sulfated zirconia thin films

Lloyd

Hansen

Ranke

et al. 2011

Applied Catalysis A: General

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Nanocrystalline thin films of the alkane skeletal isomerisation catalyst sulfated zirconia were successfully deposited on a silicon substrate in order to allow the application of surface science techniques. Thermal treatment of the films was optimised to chemically mimic the powder preparation process, resulting in films possessing the essential features (including tetragonal phase, nanocrystallinity and sulfur content of ~3 atomic %) of active powder catalysts. The n-butane adsorption-desorption equilibrium under isobaric conditions (10 -8 to 10 -6 hPa) over the temperature range 300-100 K was monitored by photoelectron spectroscopy. Analysis of the isobars revealed strong and weak n-butane chemisorption sites, releasing heats of between 59-40 and 47-34 kJ/mol, corresponding to 5 and 25% of a monolayer coverage, respectively. The total amount of chemisorbed n-butane coincides with the estimated number of surface sulfate groups. An increase in adsorption heat was observed between coverages of ~5-8% of a monolayer, indicating adsorbate-adsorbate interactions. It follows that adjacent sites are present and isomerisation by a bimolecular surface reaction is feasible. Physisorption on the films generates heats of ~28 kJ/mol, for coverages from 30% up to a complete monolayer. Multilayer adsorption results in the formation of an electrically insulating adsorbate structure. It is proposed that the strong chemisorption sites correspond to an interaction with a minority disulfate species.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Adsorption–desorption equilibrium investigations of n-butane on nanocrystalline sulfated zirconia thin films

Lloyd

Hansen

Ranke

et al. 2011

Applied Catalysis A: General

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“…In addition, solid catalysts have the potential to be regenerated and are environmentally benign, allowing multiple reuse with little waste released to the environment. Among solid acid catalysts, sulfated zirconia (SZ) has received considerable attention over the last 20 years due to its strong acid properties (Hino et al, 1980;Song et al, 1996;Arata et al, 1988). Several solid acids (zeolites, ion exchange resins, and mixed metal oxides) were investigated as catalysts for the esterification of dodecanoic acid with 2-ethylhexanol, 1-propanol and methanol at 130-180 o C and sulfated zirconia was considered to be the best.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of biodiesel from Neem oil using sulfated zirconia via tranesterification

Muthu¹,

Sathyaselvabala²,

Varathachary³

et al. 2010

Braz. J. Chem. Eng.

109

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-Sulfated zirconia (SZ) is a widely used catalyst, which is synthesized by a solvent free method and the synthesized catalyst has been characterized. Neem Methyl Ester (Biodiesel) was prepared by a two-step process of esterification and transesterification from Neem oil with methanol in the presence of catalyst. Acid catalyst was used for the esterification and alkali catalyst (KOH) for the transesterification reaction. Optimal Free Fatty Acid (FFA) conversion was achieved using 1 wt% SZ as an acid catalyst with a methanol-to-oil molar ratio of 9:1, temperature of 65°C and reaction time of 2 h. The acid value was reduced to 94% of the raw oil (24.76 mg KOH/g), which confirmed the conversion. Consequently, this pretreatment reduces the overall complexity of the process and a conversion efficiency of 95% is achieved when pretreated oil reacts with methanol in the presence of KOH.

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“…1 The activity was first explained by superacidic sites that are able to ionize bases as weak as alkanes. Even though many groups could not detect superacidic sites in sulfated zirconia, [2][3][4] part of the community is not convinced and the term is still used for this type of materials in the recent literature.…”

Section: Introductionmentioning

confidence: 99%

Effect of Mn and Fe on the Reactivity of Sulfated Zirconia toward H₂ and n-Butane: A Diffuse Reflectance IR Spectroscopic Investigation

et al. 2005

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Sulfated zirconia (SZ) and sulfated zirconia promoted with 2 wt% manganese (MnSZ) or iron (FeSZ), all active in n-butane isomerization, were investigated using diffuse reflectance Fourier transform IR spectroscopy (DRIFTS). By adsorption of H 2 at 77 K or of n-butane at room temperature it was found that the promoters neither enhance the Lewis nor the Brønsted acidity. The acid strength of both samples is not higher than that of zeolites. In a batch experiment using 70 hPa of H 2 , SZ did not react at 473 K. Reaction of H 2 with MnSZ produced water (band at 5242 cm -1 ) and a decrease in the sulfate groups (multiple bands). Heating of SZ in 10 hPa n-butane to 573 K caused total reduction of sulfate to H 2 S (2583, 2570 cm -1 ) and partial and total oxidation of butane to olefinic species (3062 cm -1 ), CO 2 , and water. MnSZ and FeSZ reacted with n-butane already at 373 K; products of skeletal isomerization (methyne CH vibration at 2910 cm -1 ) were detected and sulfate groups were consumed. Rather than increasing the acidity, the promoters enhance the oxidation potential of sulfate and facilitate alkane activation via oxidative dehydrogenation.

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Synthesis of solid superacid catalyst with acid strength of H₀⩽–16.04

Cited by 375 publications

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Adsorption–desorption equilibrium investigations of n-butane on nanocrystalline sulfated zirconia thin films

Adsorption–desorption equilibrium investigations of n-butane on nanocrystalline sulfated zirconia thin films

Synthesis of biodiesel from Neem oil using sulfated zirconia via tranesterification

Effect of Mn and Fe on the Reactivity of Sulfated Zirconia toward H₂ and n-Butane: A Diffuse Reflectance IR Spectroscopic Investigation

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Synthesis of solid superacid catalyst with acid strength of H0⩽–16.04

Cited by 375 publications

References 0 publications

Adsorption–desorption equilibrium investigations of n-butane on nanocrystalline sulfated zirconia thin films

Adsorption–desorption equilibrium investigations of n-butane on nanocrystalline sulfated zirconia thin films

Synthesis of biodiesel from Neem oil using sulfated zirconia via tranesterification

Effect of Mn and Fe on the Reactivity of Sulfated Zirconia toward H2 and n-Butane: A Diffuse Reflectance IR Spectroscopic Investigation

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Synthesis of solid superacid catalyst with acid strength of H₀⩽–16.04

Effect of Mn and Fe on the Reactivity of Sulfated Zirconia toward H₂ and n-Butane: A Diffuse Reflectance IR Spectroscopic Investigation