Zeolites: Catalysts for Organic Syntheses

Hölderich, Wolfgang F.; Hesse, M.; Näumann, Fritz

doi:10.1002/anie.198802261

Cited by 503 publications

(131 citation statements)

References 174 publications

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“…Depending on the framework type, Si/Al ratio and synthesis condition, the Brönsted/Lewis acid site ratio can be varied over a wide range. Accompanied with the size/ shape selective host-guest chemistry, such framework acidity allows zeolites to be used as very valuable heterogeneous catalyst that can convert raw-chemicals to the value-added products, giving the biggest impact on the industry [2][3][4].…”

Section: Introduction To Zeolites and Their Catalysismentioning

confidence: 99%

Hierarchically Nanoporous Zeolites and Their Heterogeneous Catalysis: Current Status and Future Perspectives

Somorjai

2014

Catal Lett

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The research field of hierarchically nanoporous zeolites has been growing at an enormous pace over the past decades. Hierarchically nanoporous zeolites have versatile structural properties such as high surface area and large pore volume that can alleviate diffusional limitations of conventional zeolites with solely microporous framework. In this review, various synthesis strategies to hierarchically nanoporous zeolites and their structural advantages in catalytic reactions will be reviewed. In the first part, many novel synthetic approaches for hierarchically nanoporous zeolites such as post-demetallation, softtemplating, hard-templating, and dual-pore-generating surfactant-directed methods will be introduced. In the second part, catalytic applications of hierarchically nanoporous zeolites on various chemical reactions involving isomerization, cracking, alkylation and oxidation will be discussed. The present comprehensive review will provide future opportunities and perspectives on the research of hierarchically nanoporous zeolites including their applications to catalytic reactions.

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Section: Introduction To Zeolites and Their Catalysismentioning

confidence: 99%

Hierarchically Nanoporous Zeolites and Their Heterogeneous Catalysis: Current Status and Future Perspectives

Somorjai

2014

Catal Lett

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“…The Brønsted acid sites consist of protons adsorbed on the bridged oxygen (the Si-OH groups on the surface) and Lewis acid sites consist of three valence Al atoms (generated after dehydration through calcination). 26 The proposed structure for the occurrence of nitrolysis reaction on the surface of H-ZSM-5 is shown in Scheme 2.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of CL-20 from TADB in a One-Pot Method by Zeolite/HNO₃as a New Nitrolysis System

Bayat¹,

Hajighasemali²,

Mohajeri³

2016

Journal of the Brazilian Chemical Society

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Hexanitrohexaazaisowurtzitane is the most powerful non-nuclear explosive in the world. Herein, a greener and safer new one-pot method for the synthesis of CL-20 from tetraacetyldibenzylhexaazaisowurtzitane (TADB) has been developed through zeolite/98% HNO 3 . The H-ZSM-5 catalyst, with both Brønsted and Lewis acid sites, indicated higher catalytic activity. The reaction using H-ZSM-5 has been optimized with respect to reaction temperature, reaction time, amount of acid and amount of catalyst to substrate ratio. Keywords: debenzylation, nitrolysis, zeolite, tetraacetyldibenzylhexaazaisowurtzitane, CL-20Introduction 2 , 4 , 6 , 8 , 1 0 , 1 2 -H e x a n i t r o -2 , 4 , 6 , 8 , 1 0 , 1 2 -hexaazaisowurtzitane , first proposed by Willer 1 and synthesized by Nielsen et al., 2 has been subjected to extensive studies.3 It is a well-known caged nitramine with significantly higher density (e-form), 4 higher performance and minimum signature than the other nitramines (HMX, RDX); therefore, CL-20 has found numerous military applications. 5 All the processes for CL-20 synthesis are based on the same starting materials. 6 In the first step, the hexa substituted hexaazaisowurtzitane derivatives are formed in the condensation reactions (glyoxal and primary amines). Subsequently, CL-20 is prepared by debenzylation and nitration of hexaazaisowurtzitane derivatives. 9 have been introduced for the synthesis of CL-20 from TADB. The preparation of CL-20 in the final step requires the use of HNO 3 /H 2 SO 4 which has many disadvantages including formation of environmentally unfriendly wastes that are expensive to dispose of, strong acidic media, over nitration and safety problems. Presently, the environmental concerns would not allow such means of disposal; thus, there still remains a need to develop commercially valuable process and environment-friendly methods for preparation of CL-20. 10The synthesis of CL-20 from TADB by applying melamine hydrogen sulfate/HNO 3 11 and acidic ionic liquids/HNO 3 12 in the one-pot reactions is reported in the recent studies of these authors. Nevertheless, these methods (Table 1) are affected by the use of stoichiometric quantities of expensive reagents and the high temperature of reaction which is a drawback of industrial scales.Zeolites, with their unique advantages of high thermal and acid stability and high selectivity (through homogeneous pore shape and size with their defined cages and channels) have been considered at industrial scale. [13][14][15] Zeolite is applied in catalytic cracking, isomerization and alkylation, as well as in the nitration reactions, including nitration of xylene, 16 To the best knowledge of the authors of this article, no report is available in the literature where a zeolite was Synthesis of CL-20 from TADB in a One-Pot Method by Zeolite/HNO 3 as a New Nitrolysis System J. Braz. Chem. Soc. 1104 applied in nitrolysis of the substrate. In this study, the zeolite/HNO 3 as a nitrolysis system (nitro-debenzylation, nitro-deacetylation) was applied in order to prepar...

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“…Different acids, including KSF montmorillonite, 13X zeolite (20,21), and neat p-toluenesulfonic acid (PTSA), were tested. In the first case, the effect of isopropenyl acetate as a water scavenger was studied.…”

Section: Acid Rcooh + R'oh Rcoor' + H20mentioning

confidence: 99%

The synthesis of esters under microwave irradiation using dry-media conditions

Loupy¹,

Petit²,

Ramdani³

et al. 1993

Can. J. Chem.

147

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Zeolites: Catalysts for Organic Syntheses

Cited by 503 publications

References 174 publications

Hierarchically Nanoporous Zeolites and Their Heterogeneous Catalysis: Current Status and Future Perspectives

Hierarchically Nanoporous Zeolites and Their Heterogeneous Catalysis: Current Status and Future Perspectives

Synthesis of CL-20 from TADB in a One-Pot Method by Zeolite/HNO₃as a New Nitrolysis System

The synthesis of esters under microwave irradiation using dry-media conditions

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Zeolites: Catalysts for Organic Syntheses

Cited by 503 publications

References 174 publications

Hierarchically Nanoporous Zeolites and Their Heterogeneous Catalysis: Current Status and Future Perspectives

Hierarchically Nanoporous Zeolites and Their Heterogeneous Catalysis: Current Status and Future Perspectives

Synthesis of CL-20 from TADB in a One-Pot Method by Zeolite/HNO3as a New Nitrolysis System

The synthesis of esters under microwave irradiation using dry-media conditions

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Synthesis of CL-20 from TADB in a One-Pot Method by Zeolite/HNO₃as a New Nitrolysis System