Effect of CeO2 and La2O3 on the Activity of CeO2−La2O3/Al2O3-Supported Pd Catalysts for Steam Reforming of Methane

Intensifying strategy of ionic liquids for Pd-based catalysts in anthraquinone hydrogenation

Pd–IL complex catalyst was first employed in anthraquinone hydrogenation. ILs are uniformly dispersed around Pd species, which adjust acidic sites, accomplish charge transfers, stretch CO bond lengths and promote occurrence of desirable reactions.

Roles of noble metals (M = Ag, Au, Pd, Pt and Rh) on CeO2 in enhancing activity toward soot oxidation: Active oxygen species and DFT calculations

The effects of noble metal (M = Ag, Au, Pd, Pt, and Rh) on CeO₂ in enhancing the activity toward soot oxidation were studied through experimental methods and density functional theory (DFT) calculations. Each noble metal (3 mol.%) was supported on CeO₂ (M/CeO₂) and the properties of the catalysts were verified by XRD, HRTEM, N₂ physisorption, CO chemisorption, XPS, and H₂-TPR results. The noble metal was highly dispersed over CeO₂, except for Au due to the sintering of Au, and the reducibility of the catalysts was greatly improved according to degree of the interaction between each noble metal and CeO₂. The activities of M/CeO₂ catalysts for soot oxidation were better than that of CeO₂, and followed the order Rh/CeO₂ > Ag/CeO₂ > Pt/CeO₂ > Au/CeO₂ > Pd/CeO₂ > CeO₂. Moreover, our DFT calculations showed that vacancy formation energy was gradually lowered in the following order: CeO₂ > Pd₄/CeO₂ > Pt₄/CeO₂ > Au₄/CeO₂ = Ag₄/CeO₂ > Rh₄/CeO₂, which was similar order with experimental activity. In addition, the electronic states of the p and f orbitals of CeO₂ were studied to compare with the occupied Ce 4f electrons, which affect the redox property. Rh/CeO₂ and Ag/CeO₂ showed the improved soot oxidation activity, with an enhanced ability to generate oxygen vacancy formation and oxygen adsorption and increased electron transfer. Consequently, the experimental and DFT calculation results revealed the roles of noble metals on ceria with respect to catalytic activity.

Catalytic Performance and Characterization of Ni-Co Bi-Metallic Catalysts in n-Decane Steam Reforming: Effects of Co Addition

Co-Ni bi-metallic catalysts supported on Ce-Al2O3 (CA) were prepared with different Co ratios, and the catalytic behaviors were assessed in the n-decane steam reforming reaction with the purpose of obtaining high H2 yield with lower inactivation by carbon deposition. Physicochemical characteristics studies, involving N2 adsorption-desorption, X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR), NH3 temperature programmed reduction (NH3-TPD), SEM-energy dispersive spectrometer (EDS), and transmission electron microscope (TEM)/HRTEM, were performed to reveal the textural, structural and morphological properties of the catalysts. Activity test indicated that the addition of moderate Co can improve the hydrogen selectivity and anti-coking ability compared with the mono-Ni/Ce-Al2O3 contrast catalyst. In addition, 12% Co showed the best catalytic activity in the series Co-Ni/Ce-Al2O3 catalysts. The results of catalysts characterizations of XRD and N2 adsorption-desorption manifesting the metal-support interactions were significantly enhanced, and there was obvious synergistic effect between Ni and Co. Moreover, the introduction of 12% Co and 6% Ni did not exceed the monolayer saturation capacity of the Ce-Al2O3 support. Finally, 6 h stability test for the optimal catalyst 12%Co-Ni/Ce-Al2O3 demonstrated that the catalyst has good long-term stability to provide high hydrogen selectivity, as well as good resistance to coke deposition.

Biodiesel production by free fatty acid esterification using Lanthanum (La3+) and HZSM-5 based catalysts

In this work the use of the heterogeneous catalysts pure (LO) and sulfated (SLO) lanthanum oxide, pure HZSM-5 and SLO/HZSM-5 (HZSM-5 impregnated with sulfated lanthanum oxide (SO4(2-)/La2O3)) was evaluated. The structural characterization of the materials (BET) showed that the sulfation process led to a reduction of the SLO and SLO/HZSM-5 surface area values. FTIR showed bands characteristic of the materials and, FTIR-pyridine indicated the presence of strong Brønsted sites on the sulfated material. In the catalytic tests the temperature was the parameter that most influenced the reactions. The best reaction conditions were: 10% catalyst, 100°C temperature and 1:5 m(OA)/m(meOH) for LO, SLO, SLO/HZSM-5 and 10% catalyst, 100°C temperature and 1:20 m(OA)/m(meOH) for HZSM-5. Under these conditions the conversions were: 67% and 96%, for LO and SLO, respectively and 80% and 100%, for HZSM-5 and SLO/HZSM-5, respectively. All catalysts deactivated after the first use, but the deactivation of SLO/HZSM-5 was smaller.