Mifen Cui

Physiochemical properties of n-n heterostructured TiO2/Mo-TiO2 composites and their photocatalytic degradation of gaseous toluene

Abstract The composite TiO2/Mo-TiO2 were prepared by a modified sol-gel method. The prepared catalysts were characterized by X-ray diffraction, BET analysis, SEM, X-ray photoelectron spectroscopy, and UV–vis diffused reflectance spectroscopy techniques. The structural characterization results demonstrated that Mo was successfully doped into the TiO2 lattice and caused slight changes in the physiochemical properties. The UV–vis DRS showed a red shift of the adsorption edge to the visible region. The photocatalytic decomposition efficiencies of the catalysts were examined with toluene as a typical VOC in a continuous flow reactor. The photocatalytic activity of the n-n heterogeneous TiO2/Mo-TiO2 was greater than that of pure TiO2 and Mo-TiO2, and the catalyst containing a Mo/Ti mole ratio of 2.5% exhibited optimum photocatalytic properties. In general, a relative humidity of 35%, a higher oxygen content, a lower initial toluene concentration, and a higher UV intensity were beneficial for toluene decomposition.

Structure and properties of amorphous CeO2@TiO2 catalyst and its performance in the selective catalytic reduction of NO with NH3

Abstract Amorphous CeO 2 @TiO 2 catalyst was prepared by spontaneous deposition method and characterized by XRD, Raman spectra, TEM, N 2 physisorption, H 2 -TPR, NH 3 -TPD and FT-IR; its performance in the selective catalytic reduction (SCR) of NO with NH 3 was investigated. The results show that there is a strong interaction between Ce and Ti which are combined at atomic level. In comparison with the crystal CeO 2 /TiO 2 catalyst prepared by impregnation, the amorphous CeO 2 @TiO 2 catalyst exhibits larger surface area and pore volume, excellent redox ability and acidity, and outstanding catalytic performance in SCR. Over the CeO 2 @TiO 2 catalyst, the conversion of NO reaches 80% at 175°C and retains 96.0%–99.4% at 200–400°C. Moreover, the amorphous CeO 2 @TiO 2 catalyst also shows strong resistance to H 2 O and SO 2 poisoning.

CeO2 nanodots embedded in a porous silica matrix as an active yet durable catalyst for HCl oxidation

A unique architecture of CeO2 nanodots embedded in a porous SiO2 matrix (CeO2@SiO2) was successfully fabricated by a spontaneous deposition strategy and evaluated in the recycling of Cl2 from HCl oxidation. The nano-sized CeO2 particles with a narrow size distribution (2–4 nm) were uniformly dispersed in the amorphous SiO2 matrix. Based on the characterizations from various techniques, including XRD, SEM/(HR)TEM, H2-TPR, Raman, and XPS, it was revealed that the CeO2 nanodots in the SiO2 matrix exhibited a significant “size effect”, with characteristics such as a considerably high concentration of Ce3+, a high fraction of oxygen vancant sites, and a notably enhanced oxygen reducibility, which all affect oxygen activation and surface Cl desorption. The current CeO2@SiO2 catalyst shows superior activity (1.60 gCl2 gcat−1 h−1) and good durability (an on-stream time of 100 h at 703 K). The isolation of fine CeO2 nanodots by the SiO2 matrix is a key factor in the inhibition of sintering of CeO2 entities. Kinetic measurements indicate that catalytic activity is more dependent on the O2 partial pressure than that of HCl, suggesting that enhancement in oxygen adsorption and surface Cl desorption is crucial for improving the catalytic activity.

Iron-doped mesoporous silica, Fe-MCM-41, as an active Lewis acid catalyst for acidolysis of benzyl chloride with fatty acid

Iron-doped mesoporous silica, Fe-MCM-41, with different concentrations of Lewis acidity have been prepared by the hydrothermal method. Physicochemical properties of all Fe-MCM-41 samples were obtained via HRTEM, PXRD and N2 sorption characterization. The surface acidities were tested by NH3-TPD. The catalytic activity of all Fe-MCM-41 materials were evaluated in the acidolysis reaction of benzyl chloride with various fatty acids. The corresponding benzaldehyde and acyl chloride product were synthesized in good conversion and high atom efficiency over the catalyst with the highest Fe content.