Novel KF-TiO2catalysts for oxidative dehydrogenation of isobutane

A novel type of catalysts, KF-TiO₂, efficient for the oxidative dehydrogenation (ODH) of isobutane is presented. The effect of KF content and calcination temperature was studied. In the reaction conditions explored, the best performance (73 % selectivity to isobutene at 10.5 % conversion of isobutane) was observed over a catalyst with KF/TiO₂ = 0.2 (mol/mol). The surface properties of the catalysts were investigated by SPS (Surface Photo-voltage Spectroscopy) and XPS. The promotion effect of KF in the catalysts can be attributed to the formation of an oxyfluoro-compound, K₂Ti₄O₈F₂.     

丙烷脱氢反应中焙烧温度和反应气氛对 Pt-Sn/SAPO-34 催化性能的影响

 在不同的焙烧温度下制备了 Pt-Sn/SAPO-34 催化剂, 并使用 X 射线衍射、N2 吸附、X 射线荧光光谱、O2 脉冲烧炭、H2 程序升温还原和透射电镜等手段对催化剂进行了表征. 在微型反应器中评价了 Pt-Sn/SAPO-34 催化剂对丙烷脱氢制丙烯反应的催化性能, 考察了焙烧温度和反应气氛对催化剂性能的影响. 结果表明, 焙烧温度为 500 oC 时, 催化剂具有最佳的反应活性. 当焙烧温度高于 500 oC 时, 催化剂出现不希望的表面变化, 例如活性 Pt 位点的聚集、Pt 的团聚、Sn 的流失等. 当反应温度为 595 oC 时, Pt-Sn/SAPO-34 催化性能稳定, 且能够保持表面金属状态.     

Effect of zinc on the catalytic activity of hematite in ethylbenzene dehydrogenation

The effect of zinc on the performance of hematite-based catalysts in ethylbenzene dehydrogenation was studied. Zinc acts as a structural promoter stabilizing the active phase of the catalysts. This revised version was published online in June 2006 with corrections to the Cover Date.     

The effect of oxygen on the Ti(OBu)4—AlR3 catalytic system in the dimerization of ethylene to 1-butene

The effect of O₂ on the Ti(OBu)₄-AlR₃ catalytic system in the dimerization of ethylene to 1-butene is studied. It is shown that O₂ readily interacts with excess AlR₃ and reduces the deactivating capability of trialkylaluminium, converting it into the less reactive AlR₂OR. The optimal conditions of the dimerization reaction in the presence of O₂ are found. An explanation of the effect of O₂ on the catalytic system is proposed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 276–279, February, 1995.     

Allyl-Palladium-Catalyzed Ketone Dehydrogenation Enables Telescoping with Enone α,β-Vicinal Difunctionalization

The telescoping of allyl-palladium catalyzed ketone dehydrogenation with organocuprate conjugate addition chemistry allows for the introduction of aryl, heteroaryl, vinyl, acyl, methyl, and other functionalized alkyl groups chemoselectively to a wide variety of unactivated ketone compounds via their enone counterparts. The compatibility of the dehydrogenation conditions additionally allows for efficient trapping of the intermediate enolate with various electrophiles. The utility of this approach is demonstrated by comparison to several previously reported multistep sequences.