Qianwen Zhu,Yifan Yue,Xiejun Wang,Baohe Wang,Jing Zhu,Jing Ma
In view of the drawbacks of small specific surface area, poor thermal stability, and easy decomposition, CsPAV was modified by the organic ammonium source dimethyl diallyl ammonium chloride (DMDAAC). A series of (DMDAAC)CsPAV/SiO2 catalysts with different (DMDAAC)CsPAV loadings were prepared by an impregnation method. When DMDAAC-modified CsPAV was supported on SiO2, it exhibited a high specific surface area and more active sites. The catalytic performance of (DMDAAC)CsPAV/SiO2 was investigated by methacrolein (MAL) oxidation to methacrylic acid (MAA). The performance of the catalyst was characterized by FT-IR, XRD, TG, NH3-TPD, NMR, and XPS. There was an interaction between SiO2 and (DMDAAC)CsPAV, and the NH4+ crystalline salt was formed in the process of calcination from DMDAAC. The interaction between the formed NH4+ and SiO2 carrier prevented the decomposition of CsPAV. (DMDAAC)CsPAV/SiO2 showed high stability, and the catalytic performance was stable in the long-term evaluation test. Under the optimum conditions, the conversion of MAL was 80.8%, and the selectivity to MAA was 89.1% for 50(DMDAAC)CsPAV/SiO2.
Zhuqian Xiao,Yu Fan,Yongjie Cheng,Qiang Zhang,Qing Ge,Ruyi Sha,Jianbing Ji,Jianwei Mao
The catalytic transformation of cellulose to polyols is one of the significant strategies to overcome the shortage of fossil fuels. Here we report a simple but effective preparation method for Ni-W/SiO 2 catalysts by introduction of chelating agents (ammonium hydroxide and ethanediamine) coupled with organic reducing agent (ethylene glycol). The ethylene glycol (EG) yield from microcrystalline cellulose could reach up to 63.3% at 240 °C, 5.0 MPa H 2 for 2.0 h over 15%Ni-20%W/SiO 2 -EEG catalyst. Moreover, some key parameters of process conditions including calcining temperature, reaction temperature and time, H 2 pressure and the recycling use of catalysts were investigated. Both theoretical and experimental studies suggested that 15%Ni-20%W/SiO 2 -EEG catalyst showed the best activity and stability for cascading steps for EG formation at this reaction condition. By the detailed analysis of Ni-W/SiO 2 catalysts after calcination via FT-IR, XRD , XPS , thermogravimetry (TG), TEM and element mapping, it could be concluded that on the surface of 15%Ni-20%W/SiO 2 -EEG catalyst, the particles showed less agglomeration and more homogeneous on the surface of SiO 2 . Some Ni x W y alloys (NiW, Ni 2 W 4 C) were also formed. Furthermore, it was found that the introduction of ethanediamine could promote the actual loading of nickel and tungsten species slightly according to the analysis of ICP-OES test.
Asymmetric nanocarriers with different functions can achieve synergistic effect in cancer treatment. In this study, asymmetric carbon-silica (C-SiO 2 ) carriers were prepared for drug delivery and combining therapy. The C-SiO 2 carriers presented acorn-like structure with dendritic mesoporous silica hat and carbon body. The carbon body render the carriers photothermal effect. The prepared C-SiO 2 carriers with size around 130 nm have improving cell uptake efficiency, and excellent biocompatibility. After loading doxorubicin hydrochloride (DOX), menthol (LM) was used to seal the loaded drug (DOX@C-SiO 2 -LM). LM coating can melt above the phase transition temperature, leading to the release of loaded cargo. The DOX@C-SiO 2 -LM displayed temperature/NIR-triggered drug release.
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