Pure silica mesoporous molecular sieves MCM-41 and MCM-48 organofunctionalized with 3-aminopropyltrimethoxysilane and N-[(3-trimethoxysilyl)propyl]ethylene-diamine, respectively, were served as supports to immobilize CuCl2 with conventional impregnation method. The supported copper catalysts showed a considerable enhancement in the reaction rate in heterogeneous vapor-phase oxidative carbonylation of methanol to produce dimethyl carbonate in comparison with that obtained by CuCl2-supported nonfunctionalized mesoporous silicas under identical conditions. The electronic donation of the amino groups, the accessibility and dischargeability of reactants in the regular mesopores probably account for the good catalytic performance as evidenced by the characteristic studies with XRD, BET, FTIR, TG-DTA, and XPS.

Non-porous fumed-silica nanoparticles were used as supports for the first time to immobilize water-soluble complex HRh(CO)(P(m-C6H4SO3Na)3 (1) [P(m-C6H4SO3Na)3, i.e. trisodium salt of tri-(m-sulfophenyl)-phosphine, TPPTS] to obtain supported aqueous-phase catalysts (SAPC) (fumed-SiO2-SAPC) for hydroformylation of 1-hexene. The experimental results proved that the structure of support and the support hydration were the determining factors contributing to the hydroformylation performance. The fumed-SiO2-SAPC where the water-soluble rhodium complexes were well dispersed onto the external surface of the silica nanoparticles presented a higher hydroformylation performance over a relatively wider range of support hydration as compared to the SAPC with conventional porous granular-SiO2 support (porous SiO2-SAPC). A positive effect on the reaction performance was observed from the particle size and surface area of the fumed-silica nanoparticles. The hydroformylation performance with fumed-SiO2-SAPC was promoted by an addition of basic alkali metal salts such as Na2CO3, K2CO3, and NaH2PO4, which depressed the oxidation of ligand TPPTS to OTPPTS [OTPPTS, i.e. trisodium salt of tri-(m-sulfophenyl)-phosphine oxide, OP(m-C6H4SO3Na)3] as evidenced by 31P NMR observation.

Three crystalline compounds, SbOReO4 2H2O, Sb4Re2O13 and SbRe2O6, and several supported Re catalysts were employed as catalysts for the selective oxidation of methanol to methylal (3CH3OH

The unique performances of supported rhenium oxide catalysts for the selective oxidation of methanol to methylal (dimethoxymethane) [3CH3OH+1/2O2 f CH2(OCH3)2+2H2O] were examined in a fixed-bed flow reactor and in a pulse reactor. Rhenium oxides supported on R-Fe2O3,

The solution NMR (31P and 1H) and FTIR spectroscopies were employed to investigate the structure information of water-soluble complex HRh(CO)[P(m-C6H4SO3Na)3]3 (1) [P(m-C6H4SO3Na)3: trisodium salt of tri-(m-sulfophenyl)-phosphine, TPPTS] supported on SiO2 (1/SiO2). The 31P(1H) NMR spectra showed that a pair of new twin-peak at about 31.5, 32.1 ppm while no typical twin-peak at 44.0, 44.7 ppm for the phosphorus species ascribed to the complex 1 were observed at 1/SiO2. However, the typical phosphorus peaks for the complex 1 appeared in the case of using TPPTS or Na2CO3-preimpregnated SiO2 as supports. Moreover, the immobilization caused a considerable oxidation of the liberated TPPTS to OTPPTS (OTPPTS, i.e. OP(m-C6H4SO3Na)3: trisodium salt of tri-(m-sulfophenyl)-phosphine oxide) species as evidenced by 31P(1H) NMR spectroscopy. The phosphorus-31 peaks at 31.5, 32.1 ppm at 1/SiO2 were found to be unchanged before and after the propene hydroformylation. The FTIR results revealed that the CO band appeared at about 1870 cm−1 for the 1/SiO2 catalyst, whichwas lower than that for the precursor complex 1. It is concluded that there exists a strong interaction between the complex 1 and the acidic support of SiO2, resulting in the deformation of the Rh-phosphine complex containing less than three TPPTS ligands, which further transformed by dehydrogenation and dimerization under evacuation to form a species likely [Rh(CO)(TPPTS)2]2 as a main surface complex species at the catalyst 1/SiO2.©2002 Elsevier Science B.V. All rights reserved.