Xianlun Xu

Direct synthesis of DME over bifunctional catalyst: surface properties and catalytic performance

A series of bifunctional catalysts CuO/ZnO/ZrO2/HZSM-5 with different ZrO2 contents were prepared and characterized by surface area, XRD and XPS analysis. The catalytic system was evaluated in the development of STD process (synthesis gas-to-dimethyl ether). Based on these results, it was deduced that the incorporation of ZrO2 in CuO lattice caused the formation of Cu+ on the catalyst surface during reduction, which seems to be crucial for the high selectivity of dimethyl ether (DME) and CO conversion in the present study. Also, the promoting effect of ZrO2 on the surface structure, such as Cu/Zn ratio and Cu concentration, was closely related to the DME synthesis activity. In addition, two kinds of active components in the bifunctional catalysts are finely dispersed, maintain close contact, and consequently exhibit a high degree of ‘synergistic effect’ for the effective conversion of CO to DME. In summary, Cu+/Cu0/Zn(2−δ)+/Zn2+/ZrO2/HZSM-5 is considered to be the surface active state for the direct synthesis of DME.

Layered material γ-ZrP supported platinum catalyst for liquid-phase reaction: a highly active and selective catalyst for hydrogenation of the nitro group in para-chloronitrobenzene

Chemoselective hydrogenation of para-chloronitrobenzene without any dechlorination over Pt/gamma-ZrP catalyst proceeds effectively, which provides a clean and convenient approach to produce useful para-chloroaniline with excellent activity and selectivity.

Catalytic Combustion of Methane over CeO2-MOx (M=La3+, Ca2+) Solid Solution Promoted Pd/γ-Al2O3 Catalysts

Solid solution CeO2-MOx (M=La3+, Ca2+) promoted Pd/γ-Al2O3 catalysts were prepared by a depositionprecipitation method. The structural properties were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. The results showed that Mn+ ions incorporated into CeO2 lattice and solid solutions formed in Pd/γ-Al2O3-CeO2-MOx catalysts. The formation of solid solution was confirmed by the change in lattice parameters of CeO2 and the shift of 2θ angles as compared with pure CeO2. A strain formed in the O2- sub-lattice of CeO2 was revealed by Raman analyses, which decreased the intensity of the Raman-active band at around 463 cm-1 owing to the F2g symmetric stretching of Ce—O bond. The appearance of a new band at 615 cm-1 (in the case of Pd/γ-Al2O3-CeO2-CaO) and a shoulder at 320 cm-1 (in the case of Pd/γ-Al2O3-CeO2-La2O3) was also confirmed. Ionic Pdδ+ species were formed in the catalysts, which exhibited higher binding energies (0.5-0.6 eV higher for Pd 3d5/2) than that of normal PdO. The catalysts showed high activity and stability for low temperature methane combustion. 10% and 100% conversions of methane could be obtained at temperatures of 254 and 340 ℃, respectively, over Pd/γ-Al2O3-CeO2-La2O3 catalyst under an hourly space velocity of 50000 h-1.Abstract Solid solution CeO 2 -MO x (M=La 3+ , Ca 2+ ) promoted Pd/ γ -Al 2 O 3 catalysts were prepared by a deposition-precipitation method. The structural properties were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. The results showed that M n + ions incorporated into CeO 2 lattice and solid solutions formed in Pd/ γ -Al 2 O 3 -CeO 2 -MO x catalysts. The formation of solid solution was confirmed by the change in lattice parameters of CeO 2 and the shift of 2θ angles as compared with pure CeO 2 . A strain formed in the O 2− sub-lattice of CeO 2 was revealed by Raman analyses, which decreased the intensity of the Raman-active band at around 463 cm −1 owing to the F 2 g symmetric stretching of Ce−O bond. The appearance of a new band at 615 cm −1 (in the case of Pd/ γ -Al 2 O 3 -CeO 2 -CaO) and a shoulder at 320 cm −1 (in the case of Pd/ γ -Al 2 O 3 -CeO 2 -La 2 O 3 ) was also confirmed. Ionic Pd δ + species were formed in the catalysts, which exhibited higher binding energies (0.5−0.6 eV higher for Pd 3 d 5/2 ) than that of normal PdO. The catalysts showed high activity and stability for low temperature methane combustion. 10% and 100% conversions of methane could be obtained at temperatures of 254 and 340 °C, respectively, over Pd/ γ -Al 2 O 3 -CeO 2 -La 2 O 3 catalyst under an hourly space velocity of 50000 h −1 .