نتایج جستجو برای: reuseable catalysts
تعداد نتایج: 32969 فیلتر نتایج به سال:
Interactions between ceria (CeO2) and supported metals greatly enhance rates for a number of important reactions. However, direct relationships between structure and function in these catalysts have been difficult to extract because the samples studied either were heterogeneous or were model systems dissimilar to working catalysts. We report rate measurements on samples in which the length of t...
Studies on the development of palladium, nickel, and rhodium catalysts for the hydroamination of dienes and vinylarenes are described. Enantioselective catalysts based on palladium have been developed for the addition of arylamines to dienes and for Markovnikov addition of arylamines to vinylarenes. In addition, nickel catalysts for the addition of aliphatic amines to dienes have been developed...
Heterogeneous catalysts are receiving more importance for the transesterification of triglycerides present in any oils or fats to produce biodiesel. They are reusable, environmentally benign, could give high quality of products, and more effective than acid catalysts and enzymes for biodiesel production. Recently, heterogeneous catalysts derived from both waste industrial and biological resourc...
Solid acid catalysts are becoming of great importance within the chemical industry and their acidity is of great interest, as this determines their application, plus many of their catalytic properties can also be directly related with their acidity. There has been a drive towards heterogeneous solid acid catalysts because of the environmental concerns with safe handling and disposal of mineral ...
Supported olefin polymerization catalysts can prevent reactor-fouling problems and produce uniform polymer particles. Constrained geometry complexes (CGCs) have less sterically hindered active sites than bis-cyclopentadienyl metallocene catalysts. In the literature, micrometer-sized silica particles were used for supporting CGC catalysts, which might have strong mass transfer limitations. This ...
A series of Ni-based catalysts were prepared using hydrogen reduction of Ni/Al hydrotalcite-like compounds (Ni/Al HTlcs) synthesized by coprecipitation. The physico-chemical properties of Ni/Al hydrotalcite-like compounds and the corresponding Ni-based catalysts were characterized using inductively coupled plasma (ICP), BET surface areas, X-ray diffraction (XRD), Fourier transform infrared (FTI...
Palladium, platinum, and ruthenium supported on activated carbon were used as catalysts for the selective hydrogenation of 1-heptyne, a terminal alkyne. All catalysts were characterized by temperature programmed reduction, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. TPR and XPS suggest that the metal in all catalysts is reduced after the pretreatme...
Two flame retarded plastics have been pyrolysed in the presence of two Zeolite catalysts to remove the organobromine compounds from the derived pyrolysis oil. The flame retarded plastics were, acrylonitrile – butadiene – styrene (ABS) that was flame retarded with tetrabromobisphenol A and high-impact-polystyrene (HIPS) that was flame retarded with decabromodiphenyl ether. The two catalysts inve...
Single-wall carbon nanotubes (SWNTs) are usually produced with the help of metal catalysts that first break down various carbon species such as graphite, carbon clusters, amorphous carbon, or hydrocarbons and then release them in the form of SWNTs. These catalysts therefore must perform several functions in order to produce high quality, high yield, long SWNTs, and the finesse of these catalyst...
Despite remarkable efforts have been put into the field of Pt-shelled catalysts containing an atomically thin Pt surface layer for the oxygen reduction reaction (ORR) in the last decade, further development of new Pt-shelled catalysts is still necessary. Here, a new set of Pt-shelled catalysts by subsurface alloying with early transition metals such as Mn and Fe is predicted to be a good candid...
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