Room-temperature methane activation by a bimetallic oxide clusterAlVO4+

CH Activation on Aluminum–Vanadium Bimetallic Oxide Cluster Anions

“…The rate constant k of the reaction in the fast-flow reactor can be estimated by I = I 0 expA C H T U N G T R E N N U N G (Àk1l/u) in which I and I 0 are signal magnitudes of the clusters in the presence and absence of reagent gas, respectively; 1 is the molecular density of reactant gas; [32,97] l is the effective path length of the reactor ( % 60 mm); and u is the cluster beam velocity (%1 km s À1 ). The estimated values of k are listed in Table 1.…”

“…[86][87][88][89][90][91] The V=O bond, VO 2 moiety, or V-O-Al bridging site have been assigned as active centers in V 2 O 5 / Al 2 O 3 catalysts by different research groups. However, in gas-phase studies the active sites (O t radicals) in both anionic and cationic [32] Al/V bimetallic oxide clusters are found to be localized on the AlÀO t moiety but not the transitionmetal-related VÀO moiety. These findings suggest that for reactions on V 2 O 5 /Al 2 O 3 in very small regions (e.g., nanosized), one should bear in mind that the usually considered supporting area may act as the active site.…”

“…The higher reactivity of cationic clusters than anionic ones was quite common [45-46, 100, 111] because the presence of the positive charge may act to strengthen the interaction with hydrocarbons and enhance the effect of electron withdrawal, whereas the negative charge will reduce electron-withdrawing effects and polarize hydrocarbons less strongly. [111] It is more interesting when we compare Al 3 + , the radical is suggested to be localized on one O b atom, [32] which leads to the much lower reactivity of Al 3 VO 7 + than AlVO 4 + . From the above comparison between anionic and cationic clusters, one can see that some properties are similar in anionic and cationic systems while others may be very different in systems with different charge states.…”

“…[32] AlVO 5 4 . The higher reactivity of cationic clusters than anionic ones was quite common [45-46, 100, 111] because the presence of the positive charge may act to strengthen the interaction with hydrocarbons and enhance the effect of electron withdrawal, whereas the negative charge will reduce electron-withdrawing effects and polarize hydrocarbons less strongly.…”

Chemie mit Methan: Studieren geht über Probieren!

“…B. MgO + C, [40] MO + C (M = Ca, Sr, Ba), [41] PbO + C, [42] sie umfassen außerdem das nichtmetallische SO 2 + C, [43] die gemischten Metall/Nichtmetall-Cluster P n V 4Àn O 10 + C (n = 1, 2, 4), [44] Dimetalloxide AlVO 4 + C, [45] sowie Schema 2. Vereinfachtes Schema des Katalysezyklus der C-C-Kupplung von Methan (aus Lit.…”