Organomontmorillonites （organo-MMT） were synthesized by means of montmorillonites （MMT） modified with a series of 2-methacryloyloxy ethyl alkyl dimethyl ammonium bromide （MAAB） having different alkyl chain lengt...Organomontmorillonites （organo-MMT） were synthesized by means of montmorillonites （MMT） modified with a series of 2-methacryloyloxy ethyl alkyl dimethyl ammonium bromide （MAAB） having different alkyl chain lengths as cationic surfactants through a cationic exchanging reaction, and were characterized by FTIR, TG, elemental analysis, and XRD. The microenvironment of the organic interlayer such as the orientation and arrangement of the alkyl chains of MAAB, as well as the properties of nanocomposite hydrogels, were also investigated. The amount of organic components absorbed on interlayer and the basal spacing of organo-MMT both increase with the increasing of alkyl length of MAAB. When carbon number of alkyl chain is in the region of 8 to 14, the alkyl chains between layers would adopt a disordered gauche conformation; while the carbon number is 16, an ordered all-trans conformation with a vertical orientation would be found together with the disordered gauche conformation according to the results of XRD and FTIR. Due to the difference of microenvironment of organic interlayer, the Young＇s moduli of the nanocomposite hydrogels increased as the alkyl chains of MAAB became longer.展开更多
A novel tetrabutyl ammonium bromide(TBAB) modified Wacker-type catalyst system supported on various supports has been investigated in the gas-phase oxidative carbonylation of methanol and CO for dimethyl carbonate(DMC...A novel tetrabutyl ammonium bromide(TBAB) modified Wacker-type catalyst system supported on various supports has been investigated in the gas-phase oxidative carbonylation of methanol and CO for dimethyl carbonate(DMC) synthesis. It is demonstrated that the SiO 2 supported Wacker-type catalysts have shown the best catalytic performance for DMC synthesis in terms of the activity and selectivity.展开更多
文摘Organomontmorillonites （organo-MMT） were synthesized by means of montmorillonites （MMT） modified with a series of 2-methacryloyloxy ethyl alkyl dimethyl ammonium bromide （MAAB） having different alkyl chain lengths as cationic surfactants through a cationic exchanging reaction, and were characterized by FTIR, TG, elemental analysis, and XRD. The microenvironment of the organic interlayer such as the orientation and arrangement of the alkyl chains of MAAB, as well as the properties of nanocomposite hydrogels, were also investigated. The amount of organic components absorbed on interlayer and the basal spacing of organo-MMT both increase with the increasing of alkyl length of MAAB. When carbon number of alkyl chain is in the region of 8 to 14, the alkyl chains between layers would adopt a disordered gauche conformation; while the carbon number is 16, an ordered all-trans conformation with a vertical orientation would be found together with the disordered gauche conformation according to the results of XRD and FTIR. Due to the difference of microenvironment of organic interlayer, the Young＇s moduli of the nanocomposite hydrogels increased as the alkyl chains of MAAB became longer.
文摘A novel tetrabutyl ammonium bromide(TBAB) modified Wacker-type catalyst system supported on various supports has been investigated in the gas-phase oxidative carbonylation of methanol and CO for dimethyl carbonate(DMC) synthesis. It is demonstrated that the SiO 2 supported Wacker-type catalysts have shown the best catalytic performance for DMC synthesis in terms of the activity and selectivity.
