Catalytic applications of metal-organic framework modified by yttriumcontaining sandwich polyoxometalate

Polyoxometalates, including heteropolyoxometalates and isopolyoxometalates, can be usedas excellent catalysts for both acid-catalyzed reactions and oxidation reactions [۱]. The synthesisand characterization of new transition-metal-substituted (d-and f-block) polyoxometalatescontinues to be a focus of considerable ongoing research. Highly tunable nature of thesecompounds, coupled with their chemically robust nature, has led to applications in catalysis,medicine and molecular magnetism [۲]. As homogeneous catalysts, polyoxometalates have a lowspecific surface area, and on the other hand, they are easily dissolved in polar environments, forthis reason, it is difficult to recovery the catalyst [۳]. Attempts to recover catalysts are of greatinterest [۴]. In order to reach this goal, homogeneous catalysts must be converted intoheterogeneous catalysts by different methods. One of these methods is to place the homogeneouscatalyst on a solid support [۵].The A-type sandwich polyoxometalates of [(PW۹O۳۴)۲(H۲OYO)۳]۱۵- was immobilized forthe first time into the porous metal-organic framework MIL-۱۰۱(Cr). The new P۲W۱۸Y۳@MIL-۱۰۱ nanocomposite characterized by means of FT-IR, XRD, TGA, SEM, EDX, BET analysis.The catalytic activity of heterogeneous catalyst was examined in the oxidation of sulfides tosulfones with H۲O۲ oxidant at room temperature.The effects of different dosages ofpolyoxometalates, type of solvent, reaction time, amount of catalysts and oxidant in this catalyticsystem were investigated. The effect of temperature on stability and catalytic activity of the newP۲W۱۸Y۳@MIL-۱۰۱ was investigated. The new new P۲W۱۸Y۳@MIL-۱۰۱ nanocompositeexhibited well recyclability and reusability in at least five consecutive reaction cycles withoutsignificant loss of activity or selectivity.

کلیدواژه ها:

yttrium sandwich type polyoxometalate ، MIL-۱۰۱(Cr) ، composite ، sulfides ، sulfones