Search

The oxidative dehydrogenation of ethane using CO2 as soft oxidant for the production of ethylene, possesses the features of valorization of light alkane and utilization of greenhouse gas. Although a significant challenge, the control of the reaction extent can provide a potential on‐purpose ethylene technology. In the present paper, CeO2 is proposed to be a promising catalyst, while the deep oxidation process of dry reforming is preferred. The SiO2 coated CeO2 catalyst can render the reaction more selective towards ethylene. Through high sensitivity low energy ion scattering spectroscopy, findings were made that SiO2 only partially covered CeO2 in the Si0.1CeO2 sample, in which the ethylene selectivity was 2.7 times as high as that of the bulk CeO2 based on the same conversion level. Further, density functional theory calculations also demonstrated that the presence of the SiO2 layer was more conducive to the desorption of ethylene. [ABSTRACT FROM AUTHOR]

The bimetallic CeNi/SiO 2 catalysts were prepared by impregnation method and characterized by N 2 adsorption/desorption, XRD, HRTEM, XPS, H 2 -chemisorption, H 2 -TPR, NH 3 -TPD, in situ pyridine FT-IR and TG etc. techniques. The results showed that the addition of ceria could help the Ni nanoparticles disperse better through keeping them from aggregating, and generate more abundant oxygen vacancy which further facilitated the reduction of nickel oxides to give more active sites through the interaction between Ce and Ni species. Meanwhile, the bimetallic catalysts involved newly the medium acidic site that was favorable for the formation of desired product γ-valerolactone (GVL) and for the improvement of coke resistance. The synergistic effect in CeNi species boosted the conversion of levulinic acid reach 82.5% with a GVL selectivity of 96.1% on 10Ce10Ni/SiO 2 sample. [Display omitted] • Catalytic conversion of bio-derived LA into GVL in gas phase. • Synergistic effect of Ce and Ni enhanced catalytic activity. • Ce was helpful for dispersing the Ni nanoparticles. • Acidity and particle size of active site affect the catalytic performance. • Coke resistance was improve by introducing Ce into Ni/SiO 2 catalyst. [ABSTRACT FROM AUTHOR]

Fe, Ni, Mn, and Ti were directly doped into CeO 2 lattice by hydrothermal method to form solid solution catalysts. Various techniques including N 2 adsorption/desorption, XRD, HRTEM, XPS, H 2 -TPR, CO 2 -TPD, O 2 -TPD, Raman, and thermogravimetric techniques were applied to study the structural evolution under the preparation/reaction conditions. The incorporation of metal elements distorted the lattice, the difference of interaction resulted in the differences of redox, oxygen activity, basicity and surface etc. properties. The catalytic conversion of ethane with CO 2 exhibited dry reforming feature on Ni doped ceria because of the in situ formed metallic Ni0, and selective oxidation feature on Fe, Mn and Ti doped samples. The number and activity of lattice oxygen played the dominant role in affecting activity and selectivity. The solid solution catalysts revealed good coke resistance. [Display omitted] • Metal-doped ceria as an efficient strategy to control product distribution. • NiCeO revealed the feature of dry reforming catalyst due to in situ generated Ni0. • The lattice oxygen activity was significantly affected by the dopants. • The abundant lattice oxygen was the basis of high activity. • Solid solution catalysts improved the coke resistance. [ABSTRACT FROM AUTHOR]

The oxidative dehydrogenation of ethane using CO2 as soft oxidant for the production of ethylene, possesses the features of valorization of light alkane and utilization of greenhouse gas. Although a significant challenge, the control of the reaction extent can provide a potential on‐purpose ethylene technology. In the present paper, CeO2 is proposed to be a promising catalyst, while the deep oxidation process of dry reforming is preferred. The SiO2 coated CeO2 catalyst can render the reaction more selective towards ethylene. Through high sensitivity low energy ion scattering spectroscopy, findings were made that SiO2 only partially covered CeO2 in the Si0.1CeO2 sample, in which the ethylene selectivity was 2.7 times as high as that of the bulk CeO2 based on the same conversion level. Further, density functional theory calculations also demonstrated that the presence of the SiO2 layer was more conducive to the desorption of ethylene. [ABSTRACT FROM AUTHOR]

Low-cost metallic nanoparticles as catalysts with good performance are highly desired for the development of hydrogen storage materials. In this work, ceria-doped CuNi nanoparticles were successfully immobilized on the surfaces of reduced graphene oxide (rGO) by a simple co-reduction approach in aqueous solution at room temperature, characterized by ICP-OES, XRD, TEM, SEM-EDS and XPS techniques. The as-synthesized CuNi-CeO 2 /rGO nanocomposites with various metal contents had been employed as heterogeneous catalysts for the hydrolytic dehydrogenation of ammonia borane (NH 3 BH 3 , AB) under mild conditions. The optimal catalyst of Cu 0.8 Ni 0.2 -CeO 2 /rGO with CeO 2 content of 13.9 mol% exhibited an excellent catalytic activity with the exceedingly high TOF value of 34.4·mol H2 ·mol catalyst −1 ·min −1 at 298 K. The apparent activation energy was calculated to be 19.1 kJ mol −1 , even lower than most of noble-metal-based catalysts for AB dehydrogenation. The detailed kinetics of AB hydrolysis catalyzed by Cu 0.8 Ni 0.2 -CeO 2 /rGO had been investigated on different concentrations of catalyst, substrate and temperatures. Moreover, the obtained in situ hydrogen from AB hydrolysis can be further applied to reduce 4-nitrophenol with a high TOF value of 8.1 min −1 at room temperature. The high catalytic activity of Cu 0.8 Ni 0.2 -CeO 2 /rGO would be contributed to the small size of CuNi-CeO 2 NPs, metal-metal synergy, and the metal-support interaction. [ABSTRACT FROM AUTHOR]