Sulfated zirconia and its modified versions as promising catalysts for industrial processes

Yadav, Ganapati D.; Nair, Jayakrishnan

doi:10.1016/s1387-1811(99)00147-x

Cited by 633 publications

(427 citation statements)

References 119 publications

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“…The changes in isotherm shape and form, as well as the observation of hysteresis suggesting generation of microporosity, are in good agreement with TEM and XRD results. This was further confirmed by a 27 Al MAS NMR investigation ( Figure 6). The sharp, symmetrical signal centered at about d = 53 ppm, which corresponds to tetrahedral aluminum, was gradually enhanced with increasing reaction time.…”

Section: Resultssupporting

confidence: 65%

Well‐Organized Zeolite Nanocrystal Aggregates with Interconnected Hierarchically Micro–Meso–Macropore Systems Showing Enhanced Catalytic Performance

Yang

Tian

Chen

et al. 2011

Chemistry A European J

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Preparation and characterization of well‐organized zeolitic nanocrystal aggregates with an interconnected hierarchically micro–meso–macro porous system are described. Amorphous nanoparticles in bimodal aluminosilicates were directly transformed into highly crystalline nanosized zeolites, as well as acting as scaffold template. All pores on three length scales incorporated in one solid body are interconnected with each other. These zeolitic nanocrystal aggregates with hierarchically micro–meso–macroporous structure were thoroughly characterized. TEM images and 29Si NMR spectra showed that the amorphous phase of the initial material had been completely replaced by nanocrystals to give a micro–meso–macroporous crystalline zeolitic structure. Catalytic testing demonstrated their superiority due to the highly active sites and the presence of interconnected micro–meso–macroporosity in the cracking of bulky 1,3,5‐triisopropylbenzene (TIPB) compared to traditional zeolite catalysts. This synthesis strategy was extended to prepare various zeolitic nanocrystal aggregates (ZSM‐5, Beta, TS‐1, etc.) with well‐organized hierarchical micro–meso–macroporous structures.

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Section: Resultssupporting

confidence: 65%

Well‐Organized Zeolite Nanocrystal Aggregates with Interconnected Hierarchically Micro–Meso–Macropore Systems Showing Enhanced Catalytic Performance

Yang

Tian

Chen

et al. 2011

Chemistry A European J

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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%

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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“…Yadav et.al formulated a mechanism to account for the inversion phenomenon observed in single pot alkylation of toluene with benzyl chloride and benzyl alcohol 19 . It was proposed that benzyl alcohol gets preferentially adsorbed on the acid site of catalyst and forms a benzyloxonium species.…”

Section: Mechanism Of the Reactionmentioning

confidence: 99%

Single Pot Benzylation of O-Xylene with Benzyl Chloride and Benzyl Alcohol Over Pillared Montmorillonites

Kurian¹,

Sugunan

2014

Polish Journal of Chemical Technology

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Improvement of product selectivity is a major concern of the day. Presence of a coreactant can alter the rate as well as product selectivity of many key reactions like Friedel-Crafts benzylation. Single pot benzylation of o-xylene with benzyl chloride and benzyl alcohol was studied over transition metal exchanged pillared clay catalysts. Complete conversion of benzyl alcohol occured within one hour with 100% monoalkylated product selectivity. The reaction of o-xylene with benzyl alcohol was found to proceed fast in presence of benzyl chloride in single pot, than when present alone as the benzylating species. This enhancement occurs at the expense of no reaction of benzyl chloride, which when present alone reacts faster than benzyl alcohol. Existence of a second transition metal exchanged between the pillars increased the rate of the reaction. A detailed investigation of the reaction variables suggested preferential adsorption of benzyl alcohol to catalyst active sites as the reason.

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Sulfated zirconia and its modified versions as promising catalysts for industrial processes

Cited by 633 publications

References 119 publications

Well‐Organized Zeolite Nanocrystal Aggregates with Interconnected Hierarchically Micro–Meso–Macropore Systems Showing Enhanced Catalytic Performance

Well‐Organized Zeolite Nanocrystal Aggregates with Interconnected Hierarchically Micro–Meso–Macropore Systems Showing Enhanced Catalytic Performance

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

Single Pot Benzylation of O-Xylene with Benzyl Chloride and Benzyl Alcohol Over Pillared Montmorillonites

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