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W.J. Roth

Bio: W.J. Roth is an academic researcher from Princeton University. The author has contributed to research in topics: Micelle & Molecular sieve. The author has an hindex of 2, co-authored 2 publications receiving 76 citations.

Papers
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Book ChapterDOI
TL;DR: The influence of surfactant/silica molar ratio(Sur/Si) in M41S syntheses was studied in the simple synthesis system consisting of tetraethylorthosilicate (TEOS), water, and the cetyltrimethylammonium(CTMA) cation at 100°C.
Abstract: 1. Summary The influence of surfactant/silica molar ratio(Sur/Si) in M41S syntheses was studied in the simple synthesis system consisting of tetraethylorthosilicate(TEOS), water, and the cetyltrimethylammonium(CTMA) cation at 100°C. As the Sur/Si increased from 0.5 to 2, the siliceous products obtained were identified and could be classified into four separate groups: MCM-4 1(hexagonal), MCM-48(cubic), thermally unstable M4 1 S, and a molecular species, the organic octamer [(CTMA)SiO2, 5]8. One of the thermally unstable structures has been identified as a lamellar phase. These results are consistent with micellar phase transformations that occur at various surfactant concentrations and reinforce the concept that micelle structures serve as templating agents for the formation of M41S type materials.

78 citations

Book ChapterDOI
TL;DR: In this article, the ability of alkyltrimethylammonium surfactants to serve as structure directing agents for the formation of microporous or mesoporous molecular sieves frameworks was explored.
Abstract: Publisher Summary The chapter explores the ability of alkyltrimethylammonium surfactants of the type C n H 2n+I (CH 3 ) 3 NBr to serve as structure directing agents, or templates, for the formation of microporous or mesoporous molecular sieves frameworks At equivalent gel compositions and reaction conditions, it was observed that the alkyl chain length of the surfactant molecule dictated the nature of the silicate product obtained as indicated by the X-ray diffraction patterns Over the entire range of synthesis temperatures examined (100–200°C) the shortest alkyl chain length surfactant (n=6), produced amorphous or microporous zeolitic materials, such as ZSM-5 The zeolite contained the intact surfactant cation consistent with a commonly observed molecular templating effect At 100°C as the surfactant chain length was increased (n=8, 10, 12, 14, and 16), the formation of mesoporous molecular sieves (MCM-41) was observed In these cases, a combination of surfactant chain length and reaction conditions favor surfactant aggregation (micelles), and hence, the formation and utilization of supramolecular templates

4 citations


Cited by
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Journal ArticleDOI
TL;DR: Corma et al. as mentioned in this paper used the Dupont Award on new materials (1995), and the Spanish National Award “Leonardo Torres Quevedo” on Technology Research (1996) on technology research (1996), to recognize the performance of zeolites as catalysts for oil refining and petrochemistry.
Abstract: It is possible to say that zeolites are the most widely used catalysts in industry They are crystalline microporous materials which have become extremely successful as catalysts for oil refining, petrochemistry, and organic synthesis in the production of fine and speciality chemicals, particularly when dealing with molecules having kinetic diameters below 10 A The reason for their success in catalysis is related to the following specific features of these materials:1 (1) They have very high surface area and adsorption capacity (2) The adsorption properties of the zeolites can be controlled, and they can be varied from hydrophobic to hydrophilic type materials (3) Active sites, such as acid sites for instance, can be generated in the framework and their strength and concentration can be tailored for a particular application (4) The sizes of their channels and cavities are in the range typical for many molecules of interest (5-12 A), and the strong electric fields2 existing in those micropores together with an electronic confinement of the guest molecules3 are responsible for a preactivation of the reactants (5) Their intricate channel structure allows the zeolites to present different types of shape selectivity, ie, product, reactant, and transition state, which can be used to direct a given catalytic reaction toward the desired product avoiding undesired side reactions (6) All of these properties of zeolites, which are of paramount importance in catalysis and make them attractive choices for the types of processes listed above, are ultimately dependent on the thermal and hydrothermal stability of these materials In the case of zeolites, they can be activated to produce very stable materials not just resistant to heat and steam but also to chemical attacks Avelino Corma Canos was born in Moncofar, Spain, in 1951 He studied chemistry at the Universidad de Valencia (1967−1973) and received his PhD at the Universidad Complutense de Madrid in 1976 He became director of the Instituto de Tecnologia Quimica (UPV-CSIC) at the Universidad Politecnica de Valencia in 1990 His current research field is zeolites as catalysts, covering aspects of synthesis, characterization and reactivity in acid−base and redox catalysis A Corma has written about 250 articles on these subjects in international journals, three books, and a number of reviews and book chapters He is a member of the Editorial Board of Zeolites, Catalysis Review Science and Engineering, Catalysis Letters, Applied Catalysis, Journal of Molecular Catalysis, Research Trends, CaTTech, and Journal of the Chemical Society, Chemical Communications A Corma is coauthor of 20 patents, five of them being for commercial applications He has been awarded with the Dupont Award on new materials (1995), and the Spanish National Award “Leonardo Torres Quevedo” on Technology Research (1996) 2373 Chem Rev 1997, 97, 2373−2419

5,290 citations

Journal ArticleDOI
TL;DR: In this paper, a review paper deals with proven and potential applications of mesoporous molecular sieves in catalysis, and is divided into two parts, respectively, dedicated to the design of solid catalysts and catalyst supports and to some relevant examples of catalytic processes.
Abstract: This review paper deals with proven and potential applications of mesoporous molecular sieves in catalysis. In addition to introduction and conclusion, the text is divided into two parts, respectively, dedicated to the design of solid catalysts and catalyst supports and to some relevant examples of catalytic processes.

440 citations

Journal ArticleDOI
TL;DR: In this article, a review of non-silica mesostructured materials based on electrostatic interactions (ionic bonding), van der Waals interactions (hydrogen bonding), and direct covalent bonding between organic and inorganic species is presented, discussed and evaluated.

242 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a piece of the work that has been achieved over the last years in the field of synthesis and characterization of mesoporous silicas modified by different metals.

240 citations

Journal ArticleDOI
TL;DR: The concept of mesoporous molecular sieves has been studied extensively in the past few decades as mentioned in this paper, with the concept of supersmplating with molecular aggregates of surfactants, which has been proposed as a mechanistic step in the formation of the sieves, expanded our idea of the classical single molecular interaction.
Abstract: The past year has seen an explosive growth in research on mesoporous molecular sieves. Major advances in understanding and exploiting the synthesis protocols and mechanism of formation of these materials have allowed designed tailoring of their composition, pore size, structure and texture. The concept of ‘supramolecular templating’ with molecular aggregates of surfactants, which has been proposed as a mechanistic step in the formation of molecular sieves, has expanded our idea of the classical single molecular interaction. Well documented, simplified synthesis preparation of these materials have allowed study of their application in fields ranging from catalytic conversion of large molecules to their functioning as nanoscopic homes where polymers, atomic arrays of metal atoms, and electronic materials can reside.

196 citations