查看更多>>摘要：Biodiesel has attracted significant attention as a potential renewable and environmentally friendly substitute for petroleum-derived diesel fuel. Conventionally, commercial biodiesel is produced via liquid base-catalyzed transesterification of triglycerides components of oil/fat with short-chain alcohols. However, homogeneous base catalysts are very sensitive to free fatty acids present in low-quality oil feedstocks, requiring additional acid pretreatment and neutralization steps which not only cause environmental pollution but also increase the overall cost of biodiesel production. Encouragingly, solid catalysts can provide a green, efficient, and economical pathway for biodiesel production using low-cost oil feedstocks such as waste cooking oil. The present review discusses recent advances in the synthesis of bifunctional solid acid/base catalysts for sustainable biodiesel production with a focus on solid catalysts bearing acid-base bifunctionality or Bronsted-Lewis dual acidity and the synergistic effect of the active sites for simultaneous esterification of free fatty acids and transesterification of triglycerides. Furthermore, this review article also provides future research directions that can guide scientists to address research gaps hampering the synthesis of effective bifunctional solid acid/base catalysts for sustainable biodiesel production.
le Roux, Wilhelm Heinrichvan Reenen, Albert J.Malgas-Enus, Rehana
13页
查看更多>>摘要：Based on recent developments on the use of Schiff-base functionalized nickel nanoparticles as pre-catalysts in the polymerization of norbornene, the potential of these nano-systems was further explored using other olefins, both aromatic and aliphatic olefins. Herein, Schiff-base functionalized NiCl2 nanoparticles were further evaluated as potential coordination polymerization catalysts for styrene employing modified methylaluminoxane (MMAO) as a co-catalyst. Furthermore, the first attempted co-polymerization of styrene with alpha-linear olefins (C-5-C-9) using nanoparticle-assisted transformation is reported. It was found that the nano-catalysts were capable of the coordination polymerization and co-oligomerization of styrene and gave relatively monodispersed medium molecular weight polymers and short chained co-oligomers with activities comparable to the complex analogs. It was further shown that the activity of the nano-catalysts as well as the Mw and PDI of the polymers/oligomers, were not dependent on the Schiff-base ligand used as capping agent nor its concentration. The nano-catalysts were also shown to exhibit stereocontrol, giving isotactic-rich atactic homo-and co-polymers.
查看更多>>摘要：The main difficulty in the liquid phase furfural hydrogenation process is the control of the selectivity to the target product among the possible ones. When copper catalysts are used, they often suffer from low stability in liquid medium. Herein, we report a general preparation method based on glycine-assisted in situ autocombustion to synthesize Cu supported catalysts. This method could lead to highly active, selective and stable catalysts in the liquid phase furfural hydrogenation. The resulting 10Cu-SBA-GLY catalyst (10 wt% Cu on SBA-15) could achieve a complete conversion of furfural to furfuryl alcohol under mild reaction conditions. Further, neither Cu leaching nor Cu NPs sintering were observed during the 5-run recycling tests, and the loss of conversion and selectivity stays below 3%. Such exceptional features make these Cu-SBA-GLY catalysts potential for the industrial appli-cations not only in furfural hydrogenation but also in other hydroconversion processes.
查看更多>>摘要：ZnO is a promising candidate for photocatalysts, whereas suffered from low activity due to the insufficient visible-light absorption and rapid recombination of photogenerated charges. In order to improve the visible-light catalytic activity of unmodified ZnO, a ZnO/Cu2O/CuO (ZCC) heterostructure photocatalyst constructed from in situ growth of Cu-based MOF (HKUST-1) on ZnO nanosheets by in-situ growth was designed for photocatalytic H2 evolution, which exhibited excellent visible-light H2 production rate of 467.1 mu mol h(-1) g(-1). It was confirmed that the enhanced photoactivity was mainly attributed to the wide visible-light absorption range and improvement of active sites. The construction of heterostructure promoted the migration and separation of photo generated charges and enhanced the synergistic effect between the multicomponent hybrid semiconductor materials. This work highlights the design of using MOFs as precursor to construct metal oxide heterostructures with ZnO nanosheets for visible-light photocatalytic H-2 production.
Chen, Hai-YingLu, JingFedeyko, Joseph M.Raj, Agnes...
13页
查看更多>>摘要：This review summarizes the recent literature reports on the development of zeolite supported Pd catalysts for the complete oxidation of methane. In-depth analysis reveals that different types of zeolite framework structures, regardless of the dimensionality, pore opening structure, and channel size, have little influence on the methane oxidation activity or the on-stream stability of the supported Pd catalysts. In contrast, the Si/Al ratio of a zeolite support plays a critical role. Both the catalytic activity and the on-stream stability of a Pd/zeolite catalyst increase with the increase of the Si/Al ratio. Catalysts supported on siliceous zeolites consistently show excellent light-off activity and remarkable on-stream stability whether in a dry or wet feed. Silanol nest defect sites in a siliceous zeolite are proposed to be the anchoring sites promoting the formation and minimizing the sintering of finely dispersed Pd nanoparticles. Remaining challenges in overcoming the sulfur poisoning effect are discussed.
Sobolev, Vladimir, IMarchuk, Alexander S.Tsybulya, Sergey V.Prosvirin, Igor P....
11页
查看更多>>摘要：The results obtained in this study show that Sb-containing catalysts MoVSbNbGdOx/SiO2 are highly active in ethane oxidative dehydrogenation to produce ethylene. The ethylene yield of 72% (79.3% ethylene selectivity and 91.1% ethane conversion) was obtained at 400 C on one of the best catalyst. The effect of Gd additives on the catalytic properties of MoVSbNbGdOx/SiO2 catalysts was investigated. The catalysts with Gd/Mo = 0.010 - 0.015 demonstrated relatively high catalytic activity coupled with high selectivity to ethylene and excellent stability in ODE reaction, but further growth of the gadolinium content (Gd/Mo = 0.02) was accompanied by the decrease in the activity and ethylene selectivity. XRD, HRTEM, SEM, XPS and adsorption methods were used to reveal the phase composition, morphology and the structure of the obtained catalysts.
NSTL
Elsevier