Acrolein/acrylonitrile structure

The CVD catalyst exhibits good catalytic performance for the selective oxidation/ammoxida-tion of propene as shown in Table 8.5. Propene is converted selectively to acrolein (major) and acrylonitrile (minor) in the presence of NH3, whereas cracking to CxHy and complete oxidation to C02 proceeds under the propene+02 reaction conditions without NH3. The difference is obvious. HZ has no catalytic activity for the selective oxidation. A conventional impregnation Re/HZ catalyst and a physically mixed Re/HZ catalyst are not selective for the reaction (Table 8.5). Note that NH3 opened a reaction path to convert propene to acrolein. Catalysts prepared by impregnation and physical mixing methods also catalyzed the reaction but the selectivity was much lower than that for the CVD catalyst. Other zeolites are much less effective as supports for ReOx species in the selective oxidation because active Re clusters cannot be produced effectively in the pores of those zeolites, probably owing to its inappropriate pore structure and acidity. 

More commonly, uranium has been used as a catalyst component for mixed-metal oxide catalysts for selective oxidation. Probably the most well known of these mixed oxide catalysts are those based on uranium and antimony. The uranium-antimony catalysts are exceptionally active and selective and they have been applied industrially. An interpretation of the catalyst structure and reaction mechanism has been reported by GrasselU and coworkers [42, 43] who discovered the catalyst The USb30io mixed oxide has been extensively used for the oxidation/ammoxida-tion reaction of propylene to acrolein and acrylonitrile. The selective ammoxida-tion of propylene was investigated by GrasseUi and coworkers [44], and it has been demonstrated that at 460 °G a 62.0% selectivity to acrolein with a conversion of 65.2% can be achieved. Furthermore, Delobel and coworkers [45] studied the selective oxidation of propylene over USb30io, which at 340 °C gave a selectivity to acrolein of 96.7%. 

Papers concerning the physical properties of polymers as the guest components in urea inclusion compounds and polymerization reactions of guest monomer molecules within the urea tunnel structure have been reviewed elsewhere. The polymers studied included poly (ethylene), poly (acrylonitrile), poly (1,3-butadiene), poly(eth-ylene oxide), poly(tetrahydrofiiran), poly(acrolein), poly(vinyl chloride), poly(ethyl acrylate), poly(lactide), poIy(lactic acid), poly(ethylene adipate). poly(ethylene succinate), acrylonitrile-ethyl acrylate copolymer, and poly(hexanediol di acrylate). 

Nickel(I) and nickel(II) olefin compounds are rare. Examples are [Ni(acac) (COD)], [NiX(COD)] (X = Br, and [NiR(olefm)(bipy)], Alkyl complexes most probably have trigonal-bipyramidal structures. They are formed as unstable intermediate compounds during reactions of [NiR2(bipy)] with olefins. Compounds containing acrolein and acrylonitrile " were also isolated ... 

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