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Research Interests: Chemistry and Nanoporous
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Titanium silicalite is an effective molecular-sieve catalyst for the selective oxidation of alkanes, the hydroxylation of phenol and the epoxidation of alkenes in the presence of H2O2 (refs 1-3). The range of organic compounds that can be... more
Titanium silicalite is an effective molecular-sieve catalyst for the selective oxidation of alkanes, the hydroxylation of phenol and the epoxidation of alkenes in the presence of H2O2 (refs 1-3). The range of organic compounds that can be oxidized is greatly limited, however, by the relatively small pore size (about 0.6 nm) of the host framework. Large-pore (mesoporous) silica-based molecular sieves have been prepared recently by Kresge et al. and Kuroda et al.; the former used a templating approach in which the formation of an inorganic mesoporous structure is assisted by self-organization of surfactants, and the latter involved topochemical rearrangement of a layered silica precursor. Here we describe the use of the templating approach to synthesize mesoporous silica-based molecular sieves partly substituted with titanium--large-pore analogues of titanium silicalite. We find that these materials show selective catalytic activity towards the oxidation of 2,6-di-tert-butyl phenol to the corresponding quinone and the conversion of benzene to phenol.
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Research Interests:
Titanium silicalite is an effective molecular-sieve catalyst for the selective oxidation of alkanes, the hydroxylation of phenol and the epoxidation of alkenes in the presence of H2O2 (refs 1-3). The range of organic compounds that can be... more
Titanium silicalite is an effective molecular-sieve catalyst for the selective oxidation of alkanes, the hydroxylation of phenol and the epoxidation of alkenes in the presence of H2O2 (refs 1-3). The range of organic compounds that can be oxidized is greatly limited, however, by the relatively small pore size (about 0.6 nm) of the host framework. Large-pore (mesoporous) silica-based molecular sieves have been prepared recently by Kresge et al. and Kuroda et al.; the former used a templating approach in which the formation of an inorganic mesoporous structure is assisted by self-organization of surfactants, and the latter involved topochemical rearrangement of a layered silica precursor. Here we describe the use of the templating approach to synthesize mesoporous silica-based molecular sieves partly substituted with titanium--large-pore analogues of titanium silicalite. We find that these materials show selective catalytic activity towards the oxidation of 2,6-di-tert-butyl phenol to the corresponding quinone and the conversion of benzene to phenol.
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... This bolaamphiphile assembly approach provides new opportunities for the preparation of lamellarmesoporous molecular sieves with hierarchical structures specifically tailored to applications as diverse as sorbents, catalysts, sensors,... more
... This bolaamphiphile assembly approach provides new opportunities for the preparation of lamellarmesoporous molecular sieves with hierarchical structures specifically tailored to applications as diverse as sorbents, catalysts, sensors, bone implants, and nanoscale devices. ...
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Hexagonal mesoporous titanosilicates with distinguishable framework charges and textural mesoporosity, namely, Ti-MCM-41 and Ti-HMS, were prepared at ambient temperature by electrostatic and neutral assembly processes, respectively.... more
Hexagonal mesoporous titanosilicates with distinguishable framework charges and textural mesoporosity, namely, Ti-MCM-41 and Ti-HMS, were prepared at ambient temperature by electrostatic and neutral assembly processes, respectively. Titanium incorporation at the 2 mol % level ...
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A neutral templating route for preparing mesoporous molecular sieves is demonstrated based on hydrogen-bonding interactions and self-assembly between neutral primary amine micelles (S degrees ) and neutral inorganic precursors (l degrees... more
A neutral templating route for preparing mesoporous molecular sieves is demonstrated based on hydrogen-bonding interactions and self-assembly between neutral primary amine micelles (S degrees ) and neutral inorganic precursors (l degrees ). The S degrees l degrees templating pathway produces ordered mesoporous materials with thicker framework walls, smaller x-ray scattering domain sizes, and substantially improved textural mesoporosities in comparison with M41S materials templated by quaternary ammonium cations of equivalent chain length. This synthetic strategy also allows for the facile, environmentally benign recovery of the cost-intensive template by simple solvent extraction methods. The S degrees 1 degrees templating route provides for the synthesis of other oxide mesostructures (such as aluminas) that may be less readily accessible by electrostatic templating pathways.
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A catalyst support comprising gamma alumina particles in which has been distributed essentially homogeneously a concentration of bismuth between 0.05 wt% and 0.1 wt%; and a concentration of phosphorus between 0.05 wt% and 0.6 wt%.
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11/1972 Argauer et al.. f1973 Chu. 8/1978 Rollmann et al. . 4,151,189 4/1979 Rubin et al.. 4,391,785 7/1983 Rosinski et al.. 4,619,820 10/1986 Walyocsik. 4,910,006 3/1990 Zones et al.. 5,057,296 10/1991. Beck. 5,098,684 3/1992 Kresge.... more
11/1972 Argauer et al.. f1973 Chu. 8/1978 Rollmann et al. . 4,151,189 4/1979 Rubin et al.. 4,391,785 7/1983 Rosinski et al.. 4,619,820 10/1986 Walyocsik. 4,910,006 3/1990 Zones et al.. 5,057,296 10/1991. Beck. 5,098,684 3/1992 Kresge. 5,102,643 4/1992 Kresge. 5,143,879 9/1992 Whitehurst. 5,334,368 8/1994. Becket al. ............ 5,593,655 1/1997 Jongkind et al. 5,637,287 6/1997 Waughan et al. ...................
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ABSTRACT
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A series of mesoporous MCM-41 and HMS silica molecular sieves have been prepared by electrostatic and neutral assembly pathways, respectively, and their properties have been compared by a variety of physical techniques. Direct S + I -... more
A series of mesoporous MCM-41 and HMS silica molecular sieves have been prepared by electrostatic and neutral assembly pathways, respectively, and their properties have been compared by a variety of physical techniques. Direct S + I - charge matching between cationic quaternary ...
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A new synthesis route to open framework mesostructures based on H-bonding and self-assembly between neutral primary amine surfactants (S°) and neutral inorganic precursors (I°) has been used to prepare hexagonal mesoporous silicas... more
A new synthesis route to open framework mesostructures based on H-bonding and self-assembly between neutral primary amine surfactants (S°) and neutral inorganic precursors (I°) has been used to prepare hexagonal mesoporous silicas containing site isolated titanium centers. These new titanosilicates, designated Ti-HMS, exhibit exceptional catalytic reactivity for the oxidation of substrates too large to access the pore structure of conventional titanosilicates, such as titanium silicalite, TS-1. The catalytic properties of Ti-HMS materials for the peroxide oxidation of 2,6- di- tert-butylphenol are compared with those of microporous TS-1 and a mesoporous Ti-MCM-41 analog prepared by an electrostatic templating mechanism using a liquid crystal quaternary ammonium cationic surfactant.
A new templating route to ordered mesoporous materials is demonstrated based on hydrogen bonding interactions and self-assembly between neutral primary amine surfactants (S°) and neutral inorganic precursors (1°). The S° I° templating... more
A new templating route to ordered mesoporous materials is demonstrated based on hydrogen bonding interactions and self-assembly between neutral primary amine surfactants (S°) and neutral inorganic precursors (1°). The S° I° templating pathway affords ordered mesoporous materials with thicker framework walls, smaller X-ray scattering domain sizes, and substantial textural mesoporosities in comparison to MCM-41 materials templated with quaternary ammonium cations. This synthetic strategy also allows for the facile, environmentally benign recovery of the cost-intensive template by simple solvent extraction methods.
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ABSTRACT
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Two series of alumina have been prepared by flash calcination (FCAL) and subsequent rehydration of “coarse” (> 50 µm) and “fine” grain size gibbsite (< 50 µm). The initial grain size of the gibbsite was found to... more
Two series of alumina have been prepared by flash calcination (FCAL) and subsequent rehydration of “coarse” (> 50 µm) and “fine” grain size gibbsite (< 50 µm). The initial grain size of the gibbsite was found to determine the degree of amorphization, water content, rehydration ability, composition and pore structure of FCAL products. Active alumina materials having pore structure parameters
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... In another development Sayari et al. ... Catal. 57: L1 (1990). 38. HR Sonawane, AV Pol, PP Moghe, SS Biswas, and A. Sudalai, Selective catalytic oxidation of arylamines to azoxybenzenes with H2O2 over Zeolites, J. Chem. Soc. Chem.... more
... In another development Sayari et al. ... Catal. 57: L1 (1990). 38. HR Sonawane, AV Pol, PP Moghe, SS Biswas, and A. Sudalai, Selective catalytic oxidation of arylamines to azoxybenzenes with H2O2 over Zeolites, J. Chem. Soc. Chem. Commun. ...
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Catalytic hydroxylation of benzene over transition-metal substituted hexagonal mesoporous siIicas ... Wenzhong Zhang, Jialiang Wang, Peter T. Tanev and Thomas J. Pinnavaia" Department of Chemistiy and Center for Fundamental Materials... more
Catalytic hydroxylation of benzene over transition-metal substituted hexagonal mesoporous siIicas ... Wenzhong Zhang, Jialiang Wang, Peter T. Tanev and Thomas J. Pinnavaia" Department of Chemistiy and Center for Fundamental Materials Research, Michigan State University, ...