Liquid Phase Oxidation Of Styrene Research Articles

Supported 12-molybdophosphoricacid: Characterization and non-solvent liquid phase oxidation of styrene

A series of solid catalysts comprising 12-molybdophosphoricacid (PM) and neutral alumina were synthesized by impregnation. The support, fresh as well as calcinated catalysts were characterized by various physical–chemical techniques. Further, the structure of PM onto the surface of the support was confirmed by 31P MAS NMR and XPS. Non-solvent liquid phase oxidation of styrene was carried out with 30% aqueous H 2O 2 as an oxidant by varying different parameters over fresh catalysts. The catalytic activity of calcinated catalysts were also evaluated by carrying out same oxidation reaction under optimized conditions. As solid catalysts, they show high conversion of styrene with good selectivity towards benzaldehyde and styrene epoxide.

Immobilization of iron tetrasulfophthalocyanine on functionalized MCM-48 and MCM-41 mesoporous silicas: Catalysts for oxidation of styrene

Iron tetrasulfophthalocyanine (FePcS) has been anchored on the surface of functionalized MCM-48 and MCM-41 silicas by means of chemical bonding to aminosilane groups. The prepared materials, FePcS/NH 2-MCM-48 and FePcS/NH 2-MCM-41, were characterized by diffuse reflectance UV–vis and infrared (IR) spectroscopies, low-angle X-ray diffraction (XRD), and surface area analysis (BET). The tendencies of FePcS absorption on functionalized MCM-48 and MCM-41 were measured by UV–vis spectroscopy. The functionalized MCM-48 showed a larger amine to silica ratio than the functionalized MCM-41. Low-angle X-ray diffraction analysis showed that, by anchoring iron tetrasulfophthalocyanine into functionalized MCM-48 and MCM-41, the intensity of main reflection decreased. The catalytic activities of the supported iron tetrasulfophthalocyanine were examined by the oxidation of styrene in the presence of tert-butyl hydroperoxide. The FePcS/NH 2-MCM-48 showed higher activity and durability in the liquid-phase oxidation of styrene under mild condition compared with the FePcS/NH 2-MCM-41 and unsupported catalyst.

Synthesis, characterization and catalytic activity of Mn(III)- and Co(II)-salen complexes immobilized mesoporous alumina

Mn(III) and Co(II)–schiff base complexes were immobilized over mesoporous alumina through the reaction of mesoporous alumina functionalized 3-aminopropyl triethoxy silane (3-APTES) and salicylic aldehyde via schiff base condensation. The surface properties of the functionalized catalysts were analyzed by a series of characterization techniques like elemental analysis, PXRD, FTIR, N 2 adsorption–desorption, TG-DTG, DR UV–vis, XPS, etc. PXRD and adsorption–desorption analysis shows that the mesostructure of alumina remains intact after various modifications, while spectral technique show the successful anchoring of the neat complexes inside the porous alumina support. The catalytic activity of the functionalized metal-salen complexes examined in the liquid phase oxidation of styrene and cyclohexene shows that the functionalized salen complexes are more active and selective than the corresponding neat metal complexes. Further, the catalyst (Mn-S-NH 2-MA) was recycled three times in the oxidation of styrene and no major change in the conversion and selectivity is observed, which shows that the immobilized metal-salen complexes are stable under the present reaction conditions.

PdCl2 CATALYZED OXIDATION OF STYRENE TO ACETOPHENONE UNDER MILD CONDITIONS

ABSTRACT PdCl2 exhibits very high catalytic activity and acetophenone selectivity for liquid-phase oxidation of styrene under mild conditions at 55 °C, H2O2/styrene = 1.15 (mole ratio) and acetone as cosolvent. The effect of cosolvents and phase transfer reagents on the reaction is investigated. The results show that the use of acetone as cosolvent or sodium dodecyl sulfate as phase-transfer reagent can accelerate the reaction. The conversion of styrene is high when the mole ratio of styrene to PdCl2 over the range of 400∼1500. The selectivity for acetophenone decreases significantly by adding some chelating ligands to the catalytic system. The selectivity for benzaldehyde decreases significantly by adding some radical inhibitor to the catalytic system. These results show that that benzaldehyde may be produced through radical auto-oxidation mechanism while acetophenone may be produced through coordination catalysis mechanism.