Methane Activation Mediated by a Series of Cerium–Vanadium Bimetallic Oxide Cluster Cations: Tuning Reactivity by Doping

Abstract

What inspired the cover image? We wished to express the reactivities of different clusters with variouss izes in av isual way, such as the quantities of bubbles comingf rom different-sized fish shown in the cover image. There are several kinds of active sites in (CeO 2) m (V 2 O 5) n + , Ce 2 O 4 + ,and V 4 O 10 + clusters, which is the key factor for controlling reactivity,a nd the active sites were put near mouths of the fish to highlight these important features.

On the Origin of the Remarkably Variable Reactivities of [AlCeOx]+ (x=2–4) towards Methane as a Function of Oxygen Content

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The thermal gas-phase reactions of the closed-shell heteronuclear metal-oxide clusters [AlCeO x ] + (x = 2-4) with methane have been explored by FT-ICR mass spectrometry and high-level quantum-chemical calculation. Whereas as eries of aluminum-containing clusters,s uch as [) n ]C + (n = 3-5), [10] and [Al 2 TaO 5 ] + , [11] are able to bring about thermal methane activation in the gas phase,o nly two types of ceriumcontaining clusters,[ (CeO 2 ) n ]C + (n = 2-4) [12] and [(CeO 2 ) m -(V 2 O 5 ) n ] + (m = 1, 2, n = 1-5; m = 3, n = 1-4), [13] have been reported to spontaneously react with methane under ambient conditions.Moreover,tothe best of our knowledge,there are no reports on thermal methane activation with Al/Ce heteronuclear clusters in the gas phase;o nt he other hand, Al/Ce-containing catalysts have already been employed in condensed-phase methane activation processes. [1] To gain further insight into these processes, quite af ew gas-phase investigations have been performed that were aimed at uncovering the associated reaction mechanisms at as trictly molecular level.

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“…[1] To gain further insight into these processes, quite af ew gas-phase investigations have been performed that were aimed at uncovering the associated reaction mechanisms at as trictly molecular level. Whereas as eries of aluminum-containing clusters,s uch as [Al 2 O 2 ]C + , [3] [Al 2 O 3 ]C + , [4] [Al 2 O 7 ]C + , [5] [YAlO 3 ]C + , [6] [VAlO 4 ]C + , [7] [PtAl 2 O 4 ]C À , [8] [Al 2 Mg 2 O 5 ]C + , [9] [(Al 2 O 3 ) n ]C + (n = 3-5), [10] and [Al 2 TaO 5 ] + , [11] are able to bring about thermal methane activation in the gas phase,o nly two types of ceriumcontaining clusters,[ (CeO 2 ) n ]C + (n = 2-4) [12] and [(CeO 2 ) m -(V 2 O 5 ) n ] + (m = 1, 2, n = 1-5; m = 3, n = 1-4), [13] have been reported to spontaneously react with methane under ambient conditions.Moreover,tothe best of our knowledge,there are no reports on thermal methane activation with Al/Ce heteronuclear clusters in the gas phase;o nt he other hand, Al/Ce-containing catalysts have already been employed in condensed-phase methane activation processes. Whereas as eries of aluminum-containing clusters,s uch as [Al 2 O 2 ]C + , [3] [Al 2 O 3 ]C + , [4] [Al 2 O 7 ]C + , [5] [YAlO 3 ]C + , [6] [VAlO 4 ]C + , [7] [PtAl 2 O 4 ]C À , [8] [Al 2 Mg 2 O 5 ]C + , [9] [(Al 2 O 3 ) n ]C + (n = 3-5), [10] and [Al 2 TaO 5 ] + , [11] are able to bring about thermal methane activation in the gas phase,o nly two types of ceriumcontaining clusters,[ (CeO 2 ) n ]C + (n = 2-4) [12] and [(CeO 2 ) m -(V 2 O 5 ) n ] + (m = 1, 2, n = 1-5; m = 3, n = 1-4), [13] have been reported to spontaneously react with methane under ambient conditions.Moreover,tothe best of our knowledge,there are no reports on thermal methane activation with Al/Ce heteronuclear clusters in the gas phase;o nt he other hand, Al/Ce-containing catalysts have already been employed in condensed-phase methane activation processes.…”

Ursachen der unterschiedlichen Reaktivität von [AlCeOx]+ (x=2–4) gegenüber Methan in Abhängigkeit vom Sauerstoffgehalt

“…Während [AlCeO 2 ] + und [AlCeO 4 ] + unter thermischen Bedingungen gegenüber Methan inert sind, reagiert [AlCeO 3 ] + spontan unter Wasserstoffatomabstraktion. Während eine Reihe von alumini-) n ]C + (n = 3-5) [10] und [Al 2 TaO 5 ] + , [11] zur thermischen Aktivierung von Methan in der Lage ist, sind nur zwei Arten von cerhaltigen Clustern, nämlich [(CeO 2 ) n ]C + (n = 2-4) [12] und [(CeO 2 ) m (V 2 O 5 ) n ] + (m = 1, 2, n = 1-5; m = 3, n = 1-4), [13] bekannt, die unter thermischen Bedingungen spontan mit Methan reagieren. [1] Um Einblicke in diese Prozesse zu gewinnen, wurden zahlreiche Gasphasenuntersuchungen durchgeführt, mit denen die Reaktionsmechanismen auf strikt molekularer Ebene aufgeklärt werden konnten.…”

“…[1] Um Einblicke in diese Prozesse zu gewinnen, wurden zahlreiche Gasphasenuntersuchungen durchgeführt, mit denen die Reaktionsmechanismen auf strikt molekularer Ebene aufgeklärt werden konnten. Während eine Reihe von alumini-) n ]C + (n = 3-5) [10] und [Al 2 TaO 5 ] + , [11] zur thermischen Aktivierung von Methan in der Lage ist, sind nur zwei Arten von cerhaltigen Clustern, nämlich [(CeO 2 ) n ]C + (n = 2-4) [12] und [(CeO 2 ) m (V 2 O 5 ) n ] + (m = 1, 2, n = 1-5; m = 3, n = 1-4), [13] bekannt, die unter thermischen Bedingungen spontan mit Methan reagieren. Während eine Reihe von alumini-) n ]C + (n = 3-5) [10] und [Al 2 TaO 5 ] + , [11] zur thermischen Aktivierung von Methan in der Lage ist, sind nur zwei Arten von cerhaltigen Clustern, nämlich [(CeO 2 ) n ]C + (n = 2-4) [12] und [(CeO 2 ) m (V 2 O 5 ) n ] + (m = 1, 2, n = 1-5; m = 3, n = 1-4), [13] bekannt, die unter thermischen Bedingungen spontan mit Methan reagieren.…”

“…[1] Um Einblicke in diese Prozesse zu gewinnen, wurden zahlreiche Gasphasenuntersuchungen durchgeführt, mit denen die Reaktionsmechanismen auf strikt molekularer Ebene aufgeklärt werden konnten. Während eine Reihe von aluminiumhaltigen Clustern, wie [Al 2 O 2 ]C + , [3] [Al 2 O 3 ]C + , [4] [Al 2 O 7 ]C + , [5] [YAlO 3 ]C + , [6] [VAlO 4 ]C + , [7] [PtAl 2 O 4 ]C À , [8] [Al 2 Mg 2 O 5 ]C + , [9] [(Al 2 O 3 ) n ]C + (n = 3-5) [10] und [Al 2 TaO 5 ] + , [11] zur thermischen Aktivierung von Methan in der Lage ist, sind nur zwei Arten von cerhaltigen Clustern, nämlich [(CeO 2 ) n ]C + (n = 2-4) [12] und [(CeO 2 ) m (V 2 O 5 ) n ] + (m = 1, 2, n = 1-5; m = 3, n = 1-4), [13] [15] [AuCH 2 ] + , [16] [AuC] + , [17] [OSiOH] + , [18] [XHfO] + (X = F, Cl, Br), [19] [TaO 2 ] + , [20] [TaO 3 ] + , [21] [Al 2 TaO 5 ] + , [11] [AuTi 3 O x ] À (x = 7, 8) [22] und [AuV 2 O 6 ] + . Während eine Reihe von aluminiumhaltigen Clustern, wie [Al 2 O 2 ]C + , [3] [Al 2 O 3 ]C + , [4] [Al 2 O 7 ]C + , [5] [YAlO 3 ]C + , [6] [VAlO 4 ]C + , [7] [PtAl 2 O 4 ]C À , [8] [Al 2 Mg 2 O 5 ]C + , [9] [(Al 2 O 3 ) n ]C + (n = 3-5) [10] und [Al 2 TaO 5 ] + , [11] zur thermischen Aktivierung von Methan in der Lage ist, sind nur zwei Arten von cerhaltigen Clustern, nämlich [(CeO 2 ) n ]C + (n = 2-4) [12] und [(CeO 2 ) m (V 2 O 5 ) n ] + (m = 1, 2, n = 1-5; m = 3, n = 1-4), [13] [15] [AuCH 2 ] + , [16] [AuC] + , [17] [OSiOH] + , [18] [XHfO] + (X = F, Cl, Br), …”