Fe and Mn mixed oxide catalysts supported on Sn-modified TiO2 for the selective catalytic reduction of NO with NH3 at low temperature

FeMn/SnxTiO2 catalysts were synthesized by introducing Sn as an additive to modify TiO2 supports, and the Sn doping could improve the SO2 tolerance and low-temperature SCR activity significantly.

Selective catalytic reduction of NOx by low-temperature NH3 over MnxZr1 mixed-oxide catalysts

MnxZr1 series catalysts were prepared by a coprecipitation method.

Influence of Cr/Zr Ratio on Activity of Cr–Zr Oxide Catalysts in Non-Oxidative Propane Dehydrogenation

Two series of chromium–zirconium mixed oxide catalysts with different Cr/Zr molar ratio are prepared by co-precipitation method. Porous structure of the catalysts is studied by low-temperature N2 adsorption–desorption. Phase composition and chromium states in the catalysts are characterized by X-ray diffraction (XRD), UV-visible spectroscopy, and temperature-programmed reduction with hydrogen (TPR-H2). The mixed catalysts are tested in non-oxidative dehydrogenation of propane at 550 °C. The catalysts synthesized without ageing of precipitate show higher activity in propane dehydrogenation due to the higher content of reducible Cr+5/+6 species due to its stabilization on the ZrO2 surface.

Physicochemical Properties of MoVTeNb Mixed Oxide Catalysts Synthesized using Different Vanadium Sources

The use of different vanadium sources in the synthesis of multi-metal MoVTeNb oxide catalysts has been investigated for their effect on the physicochemical properties of catalysts. Metal oxides were synthesized by slurry method assisted with a microwave irradiation. Vanadium pentoxide (V2O5), vanadyl sulphate (VOSO4) and ammonium metavanadate (NH4VO3) were used as the vanadium sources, respectively. X-ray diffraction (XRD) pattern showed the existence of orthorhombic (M1) phases in all catalysts. The catalyst prepared using V2O5 produced the highest formation of the phase. This was further supported by Inductive Couple Plasma-Atomic Emission Spectroscopy (ICP-AES), which showed that the V2O5 catalyst has the highest V: Mo ratio, mainly responsible for the high catalytic activity. Temperature Programmed Reduction in Hydrogen (H2-TPR) showed better reducibility for the catalyst when compared to the others. Temperature Programmed Reaction (TPRn) confirmed that the oxidants active for propane conversion into acrylic acid were originated from the lattice of the catalyst.

Synthesis of Dimethyl Carbonate by Transesterification of Propylene Carbonate with Methanol on CeO2-La2O3 Oxides Prepared by the Soft Template Method

In this study, CeO2, La2O3, and CeO2-La2O3 mixed oxide catalysts with different Ce/La molar ratios were prepared by the soft template method and characterized by different techniques, including inductively coupled plasma atomic emission spectrometry, X-ray diffraction, N2 physisorption, thermogravimetric analysis, and Raman and Fourier transform infrared spectroscopies. NH3 and CO2 adsorption microcalorimetry was also used for assessing the acid and base surface properties, respectively. The behavior of the oxides as catalysts for the dimethyl carbonate synthesis by the transesterification of propylene carbonate with methanol, at 160 °C under autogenic pressure, was studied in a stainless-steel batch reactor. The activity of the catalysts was found to increase with an increase in the basic sites density. The formation of dimethyl carbonate was favored on medium-strength and weak basic sites, while it underwent decomposition on the strong ones. Several parasitic reactions occurred during the transformation of propylene carbonate, depending on the basic and acidic features of the catalysts. A reaction pathway has been proposed on the basis of the components identified in the reaction mixture.