Redox properties and oxidation catalysis of transition metal-substituted α-K5PW11O39(M·OH2) (M=MnII, CoII, NiII, and ZnII) Keggin heteropolyacid catalysts for liquid-phase oxidation of 2-propanol

Single-site, Ni-modified Wells–Dawson-type polyoxometalate for propylene dimerization

“…31 P NMR peaks at these locations correspond to successful metalation of the lacunary POM-WD by Ni. 57–59,63 From our previous studies, single crystal XRD of Ni-POM-WD crystals indicates that the Ni sites substitute one of the three tungsten atoms in capping regions of a WD POM, eliminating the probability of the Ni sites being outside of the defect position. 59 In addition, Ni loading of unsupported Ni-POM-WD obtained by ICP corresponds to the nominal loading.…”

“…Ni-POM-WD/SBA-15 was synthesized by following reported procedures. 57–59,63,64 First, 100 g of Na 2 WO 4 ·2H 2 O (Alfa Aesar, 99.0–101.0%) was added to 350 mL of deionized water (18.2 MΩ), heated to reflux, and stirred under reflux until fully dissolved. Then, phosphoric acid (Millipore Sigma, 85%) was slowly added dropwise to the refluxing solution and stirred under reflux for 24 h. After the solution was cooled to room temperature, 100 g of potassium chloride (BDH Chemicals, 99.0–100.5%) was added to precipitate the crude mixture.…”

“…Substitution of Fe, Ag, Mn, Co, Ni, Zn, and Cu into lacunary POMs defects have been reported as redox catalysts. 54–58…”

Oxygen Adsorption and Activation on Cobalt Center in Modified Keggin Anion-DFT Calculations

“…A review of the literature shows greater attention given to systems where the cobalt cation (Co 2+ ) occupies the position of the addenda atom . Modified systems, usually synthesized as various salts, as well as the comparison with systems modified by other transition metals, were tested in oxidation reactions in the presence of hydrogen peroxide [17][18][19][20][21][22], molecular oxygen [23][24][25][26][27][28], air [29][30][31][32][33], iodosylarenes [35,36], or t-butyl hydroperoxide [37,38]. Cobalt-modified Keggin heteropolyanin exhibits high catalytic activity and selectivity in processes such as oxidation of cyclohexane [26,27,35,37,38,40], esterification of n-butanol [25,39], epoxidation of olefins (cyclohexane, 1-hexene, norbornene, cyclooctene) [25], phenol oxidation [23], oxidation of methyl isobutyrate [24], oxidation of alpha-pinene [40], oxidation of alcohols 2-propanol [19] and hexanol [20], and lactonization of diols [22].…”

A Study on the Production of Isophthalic Acid from M-xylene under the Catalysis of Cobalt and H3PW12O40/Carbon Modified by HNO3 Solution

“…They have strong Brønsted acidity approaching to superacid region, fairly high stability, and the structure with high proton mobility (Cavani 1998). Besides their high acidity, another important factors to make these compounds attractive catalysts for a number of reactions are their redox properties and pseudo-liquid behavior (Choi et al 2013). Palermo, Romanelli and Vazquez (2013) used Mobased Keggin heteropolyacids as catalysts in the green and selective oxidation of diphenyl sulfide.…”