Chinh Nguyen-Huy

Adsorptive interaction of bisphenol A with mesoporous titanosilicate/reduced graphene oxide nanocomposite materials: FT-IR and Raman analyses

Nanocomposite materials containing graphene oxide have attracted tremendous interest as catalysts and adsorbents for water purification. In this study, mesoporous titanosilicate/reduced graphene oxide composite materials with different Ti contents were employed as adsorbents for removing bisphenol A (BPA) from water systems. The adsorptive interaction between BPA and adsorption sites on the composite materials was investigated by Fourier transform infrared (FT-IR) and Raman spectroscopy. Adsorption capacities of BPA at equilibrium, qe (mg/g), decreased with increasing Ti contents, proportional to the surface area of the composite materials. FT-IR observations for fresh and spent adsorbents indicated that BPA adsorbed onto the composite materials by the electrostatic interaction between OH functional groups contained in BPA and on the adsorbents. The electrostatic adsorption sites on the adsorbents were categorized into three hydroxyl groups: Si-OH, Ti-OH, and graphene-OH. In Raman spectra, the intensity ratios of D to G band were decreased after the adsorption of BPA, implying adsorptive interaction of benzene rings of BPA with the sp2 hybrid structure of the reduced graphene oxide.

Macroporous NiMo/alumina catalyst for the hydrocracking of vacuum residue

We prepared a macro-mesoporous NiMo/alumina catalyst by the introduction of macroporosity to an alumina support, and tested its catalytic performance in the hydrocracking of vacuum residue for the first time. In this reaction, the use of the macro-mesoporous NiMo/alumina catalyst clearly led to a more desirable product distribution-a higher liquid yield and lower gas yield-than a mesoporous NiMo/alumina catalyst. This indicates that the macro-mesoporous catalyst structure facilitated hydrogenation relative to the mesoporous catalyst; for the latter, hydrocracking was relatively dominant. N2 adsorption/desorption experiments confirmed that NiMo impregnation reduced the pore size and volume, as well as the surface area, implying that the NiMo phases were located inside the mesopores and macropores. Macroporosity in the alumina support played an important role in improving the accessibility of vacuum residue to the NiMo active sites located inside pores, which are responsible for hydrogenation. By promoting hydrogenation, the macro-mesoporous NiMo/alumina catalyst increased the liquid yield of the hydrocracking of vacuum residue.