Cr-MIL-101 encapsulated Keggin phosphotungstic acid as active nanomaterial for catalysing the alcoholysis of styrene oxide

Abstract

Mesoporous chromium-based terephthalate metal-organic framework (MIL-101) encapsulated Keggin phosphotungstic acid (HPW) ] was demonstrated to be an active heterogeneous catalyst for selective catalysis of the ring opening reaction of styrene oxide with methanol achieving 99 % yield of 2-methoxy-2-phenylethanol in 20 minutes at 40 °C. Similar MIL-101 samples prepared using one-pot microwave synthesis in the absence of HPW or in the presence of hydrofluoric acid (HF) were less active. The impact of fluoride and HPW polyanions incorporation on the acidity of MIL-101 was investigated by in situ Infrared spectroscopy technique using CO as a probe molecule. Additional hydroxyl groups and Lewis acid sites are present in MIL-101(HPW) explaining the observed superior catalytic performance in styrene oxide methanolysis. IntroductionMetal-organic frameworks (MOFs) are a rapidly growing family of organic-inorganic hybrid materials built from organic ligands bridging metal ions.1 By systematic design and fine-tuning, MOF structures having high accessible porosity and pores with dimensions in the range of several angstroms to nanometres have been achieved.2 These unique and outstanding features of MOFs imparted for a vast range of promising potential applications such as gas storage,

Phosphotungstic acid encapsulated in metal-organic framework UiO-66: An effective catalyst for the selective oxidation of cyclopentene to glutaraldehyde

“…The presence of free terephthalic acid impurities in UiO-66 samples, which was difficult to be thoroughly removed by washing, was evidenced by IR spectra which showed an absorption band at 1720 cm -1 (Fig. 4) [52] . The structure of UiO-66 contains two types of cages: an octahedral cage (the large one, ca.…”

“…5(A)), which corresponds to CO physisorbed species [52,59] . In parallel at higher frequency, a quite intense and broad band appear at 2170 cm -1 for UiO-66, which maybe belong to the heterogeneity of the Lewis acid sites in UiO-66 [59] .…”

“…Peak-fitting results of the FT-IR spectra corresponding to the two samples are summarized in Fig. 5 HPWs [52] . This is in agreement with what has been observed on Cr-MIL-101 encapsulated HPWs, an active nanomaterial for catalyzing the alcoholysis of styrene oxide [52] .…”

Encapsulation of Keggin-type phosphotungstic acid into the mesopores of SBA-16 as a reusable heterogeneous catalyst for the epoxidation of olefins

“…Encapsulation of catalytically active POMs into suitable porous supports is a useful approach for designing e cient heterogeneous catalysts and a variety of porous materials have been used for this purpose [19]. Metal-Organic Frameworks (MOFs) have been used as supports for the immobilization of POMs [20][21][22][23][24][25]. However, the di culties in their preparation on the one hand and their low stability in some reaction media on the other hand have limited their wide utilization in heterogeneous catalysis.…”

Influence of Strong Electronegativity Groups -Cl as the Adsorption Center of PTA@MIL-101-NH²-Cl for the Selective Hydrolysis of Cellulose into Glucose

“…(PTA @ MIL-101) [15][16][17]. PTA @ MIL-101 plays a good catalytic performance in desulfurization, denitrification and alcoholysis [18,19]. Wang synthesized PTA @ MIL-101-NH 2 that PTA is immobilized by the chemical bond of PTA and amino groups.…”