Epoxidation of methyl oleate with hydrogen peroxide. The use of Ti-containing silica solids as efficient heterogeneous catalysts

Abstract

Titanium-silica catalysts, obtained by grafting titanocene dichloride onto mesoporous silica (MCM-41 and MCM-48) and onto nanosized pyrogenic silica, were tested in the epoxidation of methyl oleate using aqueous hydrogen peroxide. All titanium-containing materials, combined with the slow addition of hydrogen peroxide, showed good catalytic activity and comparable behaviour in terms of conversion, selectivity and yield of methyl epoxystearate, notwithstanding the morphology and the texture of the silica support. By optimizing the reaction conditions (especially, the catalyst to substrate ratio), high yields up to 91% in epoxide were obtained for Ti/MCM-41 with a high stereoselectivity (80%) for the cis-epoxide. The formation of the cis/trans-epoxide and the nature of the catalytic reaction pathway are also discussed.

Chemically Modifying Vegetable Oils to Prepare Green Lubricants

“…The epoxidation of free fatty acids/esters/vegetable oils can be carried out in the presence of peracids through an in-situ or ex-situ process by varying the reaction parameters: reactant molar ratio, temperature, nature of the solvent, presence or absence of a catalyst (mineral acids/ion exchange resins), stirring speed, type of peroxyacid (peracetic, performic, m-chloroperbenzoic acid), mode and rate of the addition of H 2 O 2 /acetic or formic acid, the reaction period, and contacting patterns (batch/semi-batch mode/azeotropic distillation) [116][117][118]. To avoid the corrosive nature and undesirable side reactions (ring opening of oxirane) of mineral acids, heterogeneous catalyst systems such as acidic ion exchange resins [119], transition metal-based catalysts such as Ti-silica [120], Nb(V)-silica [121], sulfated-SnO 2 [122] and polyoxometalate [123] have become known recently for their ability to perform the epoxidation reaction. To characterize the epoxidation products, different analytical methods, such as measurement of the iodine value, oxirane content, FTIR, 1 H NMR, and ESIMS are performed.…”

Epoxidation of methyl oleate in a TiO2 coated-wall capillary microreactor

“…This result very common for the reaction in microreactor, because lower average flow velocity turn weakens the mass transfer [35] and therefore lower oxirane yields are obtained. It is worth to note that the residence time of 2.7 min is much smaller than that of the conventional batch which required several hours [1,5,6] and is in similar order to micro-flow reactor using homogeneous catalyst (6.7 min [17] and 10.6 min [12]). …”

“…In addition, the reaction between peracid and double bond is highly exothermic (∆H = −55 kcal/mol for each double bond) [4] which may cause safety risk. In order to operate under nearly isothermal condition and for safety reason, the H 2 O 2 is slowly added or by stepwise in semi-batch operation; therefore, the long operation period (about 6-10 h) is normally required [1,5,6]. Apart from the limitation of semi-batch operation as mentioned above, a mixing of two immiscible phases (aqueous and organic phase) is also concerned.…”

“…The double bonds are converted to the oxirane ring before being used as a starting material for synthesis of several chemicals such as lubricants, stabilizer for polymers, cosmetics, pharmaceuticals, and bio-fuel additives alcohols (polyols) [1]. Moreover, the oxidative stability of FAME can be improved by modifying their structure via epoxidation reaction [2].…”

Investigation of Room Temperature Synthesis of Titanium Dioxide Nanoclusters Dispersed on Cubic MCM-48 Mesoporous Materials

“…Titania based MCM-48 materials have been utilized for selective oxidation of styrene [31], 2,6-di-tert-butylphenol [32,33], methyloleate [34], and cyclohexene [25,[35][36][37][38][39]. TiO2-MCM-48 prepared by a hydrothermal method was examined for the catalytic oxidation of cyclohexene.…”