6 research outputs found
Preparation, Characterization, and Catalytic Activity of Tin (Antimony) Substituted and Lacunar Dawson Phosphotungstomolybdates for Synthesis of Adipic Acid
No full textTin (antimony) substituted and lacunar Dawson phosphotungstomolybdates (a1-K10P2W12Mo5ÿO61, a1-K8P2W12Mo5SnO61 and a-Cs4SnP2W12Mo6O62,and a-Cs3SbP2W12Mo6O62) were synthesized and characterized by Fourier Transform Infra Red (FTIR), nuclear magnetic resonance (31P NMR), Visible Ultra Violet (UV-Vis) spectroscopy, and X-ray diffraction (XRD). Their catalytic properties were examined in the oxidation reaction of cyclohexanone at 90 °C and that of cyclohexene at 70 °C to adipic acid (AA), in presence of hydrogen peroxide and in free solvent. The effects of catalyst/substrate molar ratios, hydrogene peroxide flow rate, heteropolysalt composition, and cyclohexanol addition on AA yields were studied. The Cs4SnP2W12Mo6O62 (the most efficient) led to 61 % of AA yield from the cyclohexanone oxidation using a catalyst/substrate molar ratio of 13.3×10-4, H2O2 flow rate of 0.5 mL/h, and a reaction time of 20 h
Clean Adipic Acid Synthesis from Liquid-Phase Oxidation of Cyclohexanone and Cyclohexanol Using (NH4)xAyPMo12O40 (A: Sb, Sn, Bi) Mixed Heteropolysalts and Hydrogen Peroxide in Free Solvent
No full textSSCI-VIDE+CDFA+LMH:NESInternational audienceOxidatio
Preparation, characterization of mixed-valence antimony-tin phosphomolybdic polyoxometalates and application in the cyclohexanone oxidation in the presence of hydrogen peroxide
No full textIn this work, a series of polyoxometalates (POMs), as soluble salts of formula Sn1.5PMo12O40, SbPMo12O40 and ( and , 0–0.75) were synthesized using the cationic exchange method under stoichiometric conditions. They were characterized and tested in the oxidation of cyclohexanone using hydrogen peroxide in the absence of organic solvent, co-catalyst phase transfer compounds or surfactants. UV–Visible and X-ray photoelectron spectroscopic analyses showed a partially reduced state of POM with coexistence of the couples Mo(VI)/Mo(V), Sb(V)/Sb(III) and Sn(IV)/Sn(II), without affecting their structure, results confirmed by FT-IR and Raman spectroscopies. The reversible cyclic voltammetry analysis evidenced the valence change of the Mo species, Mo(VI)/Mo(V). The POMs are found to be active in the cyclohexanone oxidation reaction and among them the most efficient is with 49% of adipic acid yield
Preparation, characterization and reactivity of 1-vanado-11-molybdo- phosphoric acid supported on mesoporous silicate materials in the propene oxidation
No full textpeer reviewedThe H 4PMo 11VO 40 heteropolyacid (HPA) was supported at 30 wt.% by the dry impregnation method on HMS, CMI-1 and SBA-15 mesoporous materials. The state of the HPA and those of the supports were examined by nitrogen physisorption, X-ray diffraction, (DR) FT-IR and X-ray photoelectron spectroscopies, thermal analysis (TG-ATD) and scanning electron microscopy (SEM). The effect of support on the catalytic behavior of H 4PMo 11VO 40 was studied in the propene oxidation at 350 °C. It was shown that the presence of H 4PMo 11VO 40, modifies the textural properties of mesoporous materials (decrease of surface area) without destroying their structure. The interaction support-heteropolyacid leads to the formation of (SiOH 2+)(H 3PMo 11VO 40 -) surface species more stable than H 4PMo 11VO 40 species and that appear to be the active sites in the propene oxidation. © 2012 Published by Elsevier Masson SAS on behalf of Academie des sciences
Preparation of CMI-1 supported H3+xPMo12-xVxO40 for the selective oxidation of propylene
No full textpeer reviewedCatalysts, comprising 30 wt.% of heteropolyacids (HPAs) H 3+xPMo 12-xV xO 40 (x = 0-3) supported on a mesoporous material CMI-1 by dry impregnation were characterized by several techniques. Their catalytic performances were compared to those of bulk HPAs in the propylene oxidation by molecular oxygen at 350°C. The supported HPAs exhibit higher catalytic activity in propylene oxidation than the bulk ones and favoured the formation of acrolein, acetaldehyde and acetic acid, compared to the mother catalysts which lead only to the formation of COx. The enhanced oxidation catalytic activity of supported systems was attributed to the fine dispersion of H 3+xPMo 12-xVxO 40 species on the CMI-1 mesoporous material via physical adsorption, together with the fact that the structure of both CMI-1 and HPAs remained intact during the impregnation. © 2010 Elsevier B.V. All rights reserved
