Synthesis, Characterization and Applications in Catalysis of Polyoxometalate/Zeolite Composites

Abstract

An overview of the synthesis, characterization and catalytic applications of polyoxometalates/zeolites composites is given. The solids obtained by direct synthesis of the polyoxometalate in the presence of the zeolite are first described with their applications in catalysis. Those obtained by a direct mixing of the two components are then reviewed. In all cases, special care is taken in the localization of the polyoxometalate, inside the zeolite crystal, in mesopores or at the external surface of the crystals, as deduced from the characterization methods.

Preparation of PLA blends by polycondensation of D,L-lactic acid using supported 12-tungstophosphoric acid as a heterogeneous catalyst

“…Recently, we found that carbon-supported H 3 PW 12 O 40 could be used as a catalyst in the conversion of D,L-lactic acid to enantioselective blends of PLA [16]. Keggin heteropolyacid (HPA) is an important class of solid acids among which 12-tungstophosphoric acid (H 3 PW 12 O 40 , H 3 PW) is particularly important because it can be used in acid catalysis for greener processes [17, 18, 19, 20, 21]. It has been shown that the H 3 PW/C catalyst is an alternative for use in such reactions involving an inexpensive monomer of D,L-lactic acid.…”

Strategies for Incorporating Catalytically Active Polyoxometalates in Metal–Organic Frameworks for Organic Transformations

“…25,26 Due to their high solubility, low surface area, and instability under reaction conditions, the processability of POMs alone is often poor. 5 To overcome these undesirable properties, significant efforts have been made to heterogenize POMs on a variety of supports, including mesoporous silica, 27,28 high surface area carbon, 29,30 zeolites, 31 polymers, 32 metal−organic macrocycles, 33 covalent−organic frameworks, 34 and metal−organic frameworks (MOFs), among others. 35 Unlike conventional supports, MOFs offer a highly tunable, crystalline scaffold for anchoring small to large molecules.…”

Understanding the Photocatalytic Reduction of CO2with Heterometallic Molybdenum(V) Phosphate Polyoxometalates in Aqueous Media

“…Polyoxometalates (POMs) as soluble anionic metal oxide clusters of d-block transition metals in high oxidation states, typically W(VI), Mo(V,VI) or V(IV,V), exhibit redox and acid-base properties and are particularly exploited in catalysis, either in homogeneous conditions 1,2 or immobilized in solid supports. [3][4][5][6] In the hot field of solar energy conversion, although numerous studies have revealed their potentialities as catalysts for water splitting, [7][8][9][10] there have been scarce reports on POMs for CO2RR. 11,12 Besides rare examples of transition metal (M)-substituted polyoxotungstates, [13][14][15][16] reduced polyoxomolybdates (i.e.…”