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Direct conversion of methane with carbon dioxide to value‐added chemicals is attractive but extremely challenging because of the thermodynamic stability and kinetic inertness of both molecules. Herein, the first dinuclear cluster species, RhVO3−, has been designed to mediate the co‐conversion of CH4 and CO2 to oxygenated products, CH3OH and CH2O, in the temperature range of 393–600 K. The resulting cluster ions RhVO3CO− after CH3OH formation can further desorb the [CO] unit to regenerate the RhVO3− cluster, leading to the successful establishment of a catalytic cycle for methanol production from CH4 and CO2 (CH4+CO2→CH3OH+CO). The exceptional activity of Rh‐V dinuclear oxide cluster (RhVO3−) identified herein provides a new mechanism for co‐conversion of two very stable molecules CH4 and CO2. [ABSTRACT FROM AUTHOR]

Abstract: The single copper atom doped clusters CuAl4O7–9− can catalyze CO oxidation by O2. The CuAl4O7–9− clusters are the first group of experimentally identified noble‐metal free single atom catalysts for such a prototypical reaction. The reactions were characterized by mass spectrometry and density functional theory calculations. The CuAl4O9CO− is much more reactive than CuAl4O9− in the reaction with CO to generate CO2. One adsorbed CO is crucial to stabilize Cu of CuAl4O9− around +I oxidation state and promote the oxidation of another CO. The widely emphasized correlation between the catalytic reactivity of CO oxidation and Cu oxidation state can be understood at the strictly molecular level. The remarkable difference between Cu catalysis and noble‐metal catalysis was discussed. [ABSTRACT FROM AUTHOR]

Abstract: Catalytic CO oxidation by molecular O2 is an important model reaction in both the condensed phase and gas‐phase studies. Available gas‐phase studies indicate that noble metal is indispensable in catalytic CO oxidation by O2 under thermal collision conditions. Herein, we identified the first example of noble‐metal‐free heteronuclear oxide cluster catalysts, the copper–vanadium bimetallic oxide clusters Cu2VO3–5− for CO oxidation by O2. The reactions were characterized by mass spectrometry, photoelectron spectroscopy, and density functional calculations. The dynamic nature of the Cu−Cu unit in terms of the electron storage and release is the driving force to promote CO oxidation and O2 activation during the catalysis. [ABSTRACT FROM AUTHOR]

Abstract: The underlying mechanism for non‐oxidative methane aromatization remains controversial owing to the lack of experimental evidence for the formation of the first C−C bond. For the first time, the elementary reaction of methane with atomic clusters (FeC3−) under high‐temperature conditions to produce C−C coupling products has been characterized by mass spectrometry. With the elevation of temperature from 300 K to 610 K, the production of acetylene, the important intermediate proposed in a monofunctional mechanism of methane aromatization, was significantly enhanced, which can be well‐rationalized by quantum chemistry calculations. This study narrows the gap between gas‐phase and condensed‐phase studies on methane conversion and suggests that the monofunctional mechanism probably operates in non‐oxidative methane aromatization. [ABSTRACT FROM AUTHOR]

Atomic clusters are being actively studied for activation of methane, the most stable alkane molecule. While many cluster cations are very reactive with methane, the cluster anions are usually not very reactive, particularly for noble metal free anions. This study reports that the reactivity of molybdenum carbide cluster anions with methane can be much enhanced by adsorption of CO. The Mo2C2− is inert with CH4 while the CO addition product Mo2C3O− brings about dehydrogenation of CH4 under thermal collision conditions. The cluster structures and reactions are characterized by mass spectrometry, photoelectron spectroscopy, and quantum chemistry calculations, which demonstrate that the Mo2C3O− isomer with dissociated CO is reactive but the one with non-dissociated CO is unreactive. The enhancement of cluster reactivity promoted by CO adsorption in this study is compared with those of reported systems of a few carbonyl complexes. [ABSTRACT FROM AUTHOR]

Investigations of the intrinsic properties of gas-phase transition metal nitride (TMN) ions represent one approach to gain a fundamental understanding of the active sites of TMN catalysts, the activities and electronic structures of which are known to be comparable to those of noble metal catalysts. Herein, we investigate the structures and reactivities of the triatomic anions HNbN− by means of mass spectrometry and photoelectron imaging spectroscopy, in conjunction with density functional theory calculations. The HNbN− anions are capable of activating CH4 and C2H6 through oxidative addition, exhibiting similar reactivities to free Pt atoms. The similar electronic structures of HNbN− and Pt, especially the active orbitals, are responsible for this resemblance. Compared to the inert NbN−, the coordination of the H atom in HNbN− is indispensable. New insights into how to replace noble metals with TMNs may be derived from this combined experimental/computational study. [ABSTRACT FROM AUTHOR]

Investigations on the reactivity of atomic clusters have led to the identification of the elementary steps involved in catalytic CO oxidation, a prototypical reaction in heterogeneous catalysis. The atomic oxygen species O.− and O2− bonded to early-transition-metal oxide clusters have been shown to oxidize CO. This study reports that when an Au2 dimer is incorporated within the cluster, the molecular oxygen species O22− bonded to vanadium can be activated to oxidize CO under thermal collision conditions. The gold dimer was doped into Au2VO4− cluster ions which then reacted with CO in an ion-trap reactor to produce Au2VO3− and then Au2VO2−. The dynamic nature of gold in terms of electron storage and release promotes CO oxidation and OO bond reduction. The oxidation of CO by atomic clusters in this study parallels similar behavior reported for the oxidation of CO by supported gold catalysts. [ABSTRACT FROM AUTHOR]

Identification and mechanistic study of thermal methane conversion mediated by gas-phase species is important for finding potentially useful routes for direct methane transformation under mild conditions. Negatively charged oxide species are usually inert with methane. This work reports an unexpected result that the bi-metallic oxide cluster anions PtAl2O4− can transform methane into a stable organic compound, formaldehyde, with high selectivity. The clusters are prepared by laser ablation and reacted with CH4 in an ion trap reactor. The reaction is characterized by mass spectrometry and density functional theory calculations. It is found that platinum rather than oxygen activates CH4 at the beginning of the reaction. The Al2O4− moiety serves as the support of Pt atom and plays important roles in the late stage of the reaction. A new mechanism for selective methane conversion is provided and new insights into the surface chemistry of single Pt atoms may be obtained from this study. [ABSTRACT FROM AUTHOR]

Ein ‐ , zwei ‐ , dreifach: Die hochselektive doppelte H ‐ Atom ‐ Abstraktion (HAA) von Ethan und dreifache HAA von n ‐ Butan durch AuNbO3+ ‐ Cluster wurden durch Massenspektrometrie und DFT ‐ Rechnungen charakterisiert. Die mehrfachen HAAs werden durch O ‐ zentrierte Radikale initiiert und durch Au unterstützt. Die Au ‐ Atome wirken in den dreifachen HAAs als Elektronenakzeptoren und speichern ein Valenzelektronenpaar zwischen Au ‐ und Nb ‐ Atomen (siehe Bild). [ABSTRACT FROM AUTHOR]

Kinetische Energiebarrieren ganz unterschiedlichen Ursprungs behindern den katalytischen N2O/CO ‐ Redoxzyklus mit [YAlO2]+. ‐ oder [Y2O2]+. ‐ Clustern als Vermittler (siehe Schema). Während die Oxidation mit N2O für [YAlO2]+. den Flaschenhals darstellt, ist diese Oxidation für [Y2O2]+. möglich, doch die Reduktion von [Y2O3]+. durch CO läuft nicht ab. Dies ist die Folge von „Dotierungs“ ‐ Effekten, die lokale Ladungs ‐ und Spinverteilungen beeinflussen können. [ABSTRACT FROM AUTHOR]

Die gemeinsame katalytische Umsetzung von Methan mit Kohlendioxid zur Erzeugung von Synthesegas (2 H2+2 CO) umfasst komplizierte Elementarschritte, und fast alle Elementarreaktionen werden praktisch bei den gleichen Hochtemperaturbedingungen der Thermokatalyse durchgeführt. Hier zeigen wir durch massenspektrometrische Experimente, dass RhTiO2− die gemeinsame Umsetzung von CH4 und CO2 zu freiem 2 H2+CO und einem adsorbierten CO (COads) bei Raumtemperatur fördert; der einzige Elementarschritt, der die Zufuhr von externer Energie erfordert, ist die Desorption von COads vom RhTiO2CO− zur Rückbildung von RhTiO2−. Die aktuelle Studie identifiziert nicht nur eine vielversprechende aktive Spezies für die Methan‐Trockenreformierung (CO2‐Reformierung) zu Synthesegas, sondern unterstreicht auch die Bedeutung der Temperaturkontrolle über Elementarschritte in der angewandten Katalyse, die die Kohlenstoffabscheidung durch Methanpyrolyse erheblich mindern könnte. [ABSTRACT FROM AUTHOR]

Abstract: The single copper atom doped clusters CuAl4O7–9− can catalyze CO oxidation by O2. The CuAl4O7–9− clusters are the first group of experimentally identified noble‐metal free single atom catalysts for such a prototypical reaction. The reactions were characterized by mass spectrometry and density functional theory calculations. The CuAl4O9CO− is much more reactive than CuAl4O9− in the reaction with CO to generate CO2. One adsorbed CO is crucial to stabilize Cu of CuAl4O9− around +I oxidation state and promote the oxidation of another CO. The widely emphasized correlation between the catalytic reactivity of CO oxidation and Cu oxidation state can be understood at the strictly molecular level. The remarkable difference between Cu catalysis and noble‐metal catalysis was discussed. [ABSTRACT FROM AUTHOR]

Abstract: Catalytic CO oxidation by molecular O2 is an important model reaction in both the condensed phase and gas‐phase studies. Available gas‐phase studies indicate that noble metal is indispensable in catalytic CO oxidation by O2 under thermal collision conditions. Herein, we identified the first example of noble‐metal‐free heteronuclear oxide cluster catalysts, the copper–vanadium bimetallic oxide clusters Cu2VO3–5− for CO oxidation by O2. The reactions were characterized by mass spectrometry, photoelectron spectroscopy, and density functional calculations. The dynamic nature of the Cu−Cu unit in terms of the electron storage and release is the driving force to promote CO oxidation and O2 activation during the catalysis. [ABSTRACT FROM AUTHOR]