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.

The pilot test is an important procedure that ultimately leads to implementation of an optimized catalytic process. A global reaction rate was calculated from the intrinsic kinetic rate with the effectiveness factor, and the calculated value is fitted well with the experimental data, which indicates that the global reaction rate is reliable. Further, a scale-up HCl oxidation experiment has been carried out in a single-tube reactor with an inner diameter of 22 mm using shaped CeO2–CuO/Y as the catalyst. A one-dimensional fixed-bed model based on the global reaction rate was adopted to properly describe the reaction behavior in the single-tube reactor. The results have laid a valuable foundation for the industrial reactor designation and the process optimization of HCl oxidation.

A novel strategy of carbonization and subsequent carboxylation in the confined mesopores of SBA-15 was implemented to synthesize meso-structured carbon/silica(C/Si) composites with enhanced acidity. The XRD and N2 sorption measurements suggested the preservation of ordered mesoporous structure; FTIR characterization indicated that the C/Sis were successfully modified with –COOH and the acidity of COOH–C/Si material was significantly enhanced. COOH–30C/Si(A) with high COOH density of 2.61 mmol/g and retained mesoporous structure exhibited superior activity for dichlorohydrin production. Through the optimization of reaction variables, as high as 65.7 %, the yield of DCH, can be achieved over COOH–30C/Si(A) after 12 h reaction under 130 °C. Meanwhile, it was 100 % that the conversion of the glycerol can be reached. A significant issue, good durability, especially for practical application, was verified through five consecutive cycles with the optimal reaction variables.

CexZr1–xO2 oxides prepared by a soft reactive grinding (SRG) procedure have been investigated as the catalysts for HCl oxidation. The results show that the catalytic activities and stabilities of CexZr1–xO2 oxides are remarkably dependent on the Ce/Zr ratio. A correlation between the physicochemical properties and catalytic performances of these samples reveals that the cubic phase in CexZr1–xO2 with higher oxygen storage capacity (OSC) is more active for HCl oxidation, but the tetragonal phase is crucial to the stability of the catalysts. The Ce0.5Zr0.5O2 catalyst with mixed phases and the highest OSC (80 μmolO2·gcat–1) exhibits an excellent activity (1.89 gCl2·gcat–1·h–1 at 430 °C) and stability (300 h) in the target reaction. Kinetic studies show that both O2 and HCl competed for the active sites rendering desorption of surface Cl as the rate-determining step. Accelerating the replacement of surface Cl by O2 is essential for improving the activity of Ce0.5Zr0.5O2.

Amorphous CeO2@TiO2 catalyst was prepared by spontaneous deposition method and characterized by XRD, Raman spectra, TEM, N2 physisorption, H2-TPR, NH3-TPD and FT-IR; its performance in the selective catalytic reduction (SCR) of NO with NH3 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 CeO2/TiO2 catalyst prepared by impregnation, the amorphous CeO2@TiO2 catalyst exhibits larger surface area and pore volume, excellent redox ability and acidity, and outstanding catalytic performance in SCR. Over the CeO2@TiO2 catalyst, the conversion of NO reaches 80% at 175°C and retains 96.0%–99.4% at 200–400°C. Moreover, the amorphous CeO2@TiO2 catalyst also shows strong resistance to H2O and SO2 poisoning.

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.