Metal-Substituted Microporous Aluminophosphates

This chapter aims to present the zeotypes aluminophosphates (AlPOs) as a complementary alternative to zeolites in the isomorphic incorporation of metal ions within all-inorganic microporous frameworks as well as to discuss didactically the catalytic consequences derived from the distinctive features of both frameworks. It does not intend to be a compilation of either all or the most significant publications involving metal-substituted microporous aluminophosphates. Families of AlPOs and zeolites, which include metal ion-substituted variants, are the dominant microporous materials. Both these systems are widely used as catalysts, in particular through aliovalent metal ions substitution. Here, some general description of the synthesis procedures and characterization techniques of the MeAPOs (metal-contained aluminophosphates) is given along with catalytic properties. Next, some illustrative examples of the catalytic possibilities of MeAPOs as catalysts in the transformation of the organic molecules are given. The oxidation of the hardly activated hydrocarbons has probably been the most successful use of AlPOs doped with the divalent transition metal ions Co2+, Mn2+, and Fe2+, whose incorporation in zeolites is disfavoured. The catalytic role of these MeAPOs is rationalized based on the knowledge acquired from a combination of the most advanced characterization techniques. Finally, the importance of the high specificity of the structure-directing agents employed in the preparation of MeAPOs is discussed taking N,N-methyldicyclohexylamine in the synthesis of AFI-structured materials as a driving force. It is shown how such a high specificity could be predicted and how it can open great possibilities in the control of parameters as critical in catalysis as crystal size, inter-and intracrystalline mesoporosity, acidity, redox properties, incorporation of a great variety of heteroatom ions or final environment of the metal site (surrounding it by either P or Al)

Homogeneous and heterogeneous catalysts for multicomponent reactions

[EN] Organic synthesis performed through multicomponent reactions is an attractive area of research in organic chemistry. Multicomponent reactions involve more than two starting reagents that couple in an exclusive ordered mode under the same reaction conditions to form a single product which contains the essential parts of the starting materials. Multicomponent reactions are powerful tools in modern drug discovery processes, because they are an important source of molecular diversity, allowing rapid, automated and high throughput generation of organic compounds. This review aims to illustrate progress in a large variety of catalyzed multicomponent reactions performed with acid, base and metal heterogeneous and homogeneous catalysts. Within each type of multicomponent approach, relevant products that can be obtained and their interest for industrial applications are presented.The authors wish to gratefully acknowledge the Generalitat Valenciana for the financial support in the project CONSOLIDER-INGENIO 2010 (CSD2009-00050)Climent Olmedo, MJ.; Corma Canós, A.; Iborra Chornet, S. (2012). Homogeneous and heterogeneous catalysts for multicomponent reactions. RSC Advances. 2(1):16-58. https://doi.org/10.1039/c1ra00807bS16582

A computational study of the stretching frequencies of Brønsted acid sites in SAPO STA-7:preliminary comparison with infrared

The acidity of the Brønsted sites in SAPO STA-7 material is investigated by atomistic simulation techniques. The long-range interactions mainly govern the acidity where as the short-range contributions have only a limited degree of influence. The calculated population of the OH stretching frequencies for a STA-7 sample with 4.8 silicon atoms per unit cell, predicts a broad distribution ranging from 3560 cm-1 to 3585 cm-1 which is confirmed by Infrared Spectroscopy.</p