Association Complex Formation in Gas-Phase Ta Cluster Reactions with Simple Alkanes:  Probing the Role of Entropy in Rate Determination for Barrierless Adsorption Processes

Abstract

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Reaction of niobium and tantalum neutral clusters with low pressure, unsaturated hydrocarbons in a pickup cell: From dehydrogenation to Met-Car formation

“…In contrast to the rather extensive investigation of niobium cluster chemistry for ions and neutrals, only a few studies of neutral tantalum clusters reacting with saturated hydrocarbons ͑ethane, propane, n-butane, isobutane, and neopentane͒ in a fast flow reactor ͑high pressure͒ are reported. 22,23 The depletion rate of Ta n clusters is found to be lower than the gas collision rate by two to three orders of magnitude, implying a weak reaction between Ta n and saturated hydrocarbons.…”

Autocatalytic gas-phase dehydrogenation of ethane

“…Experimental measurement [19] and numerical simulation data [20] concentrated mainly on the route of formation of intermediates [21][22][23][24][25][26], and the distribution of final products [27]. Interaction of hydrocarbons with catalysts has also been studied [28][29][30].…”

Reaction of carbon monoxide and hydrogen on neutral Nb8 clusters in the gas phase

“…Strong size dependent reactivity is observed with D 2 but not with CO. No reports are found for the reaction of Ta n with CO and D 2 / H 2 , and only reactions with nitrogen, benzene, and aliphatic hydrocarbons are investigated for Ta n . 20,[26][27][28] Previous flow tube reactor studies [21][22][23] suggest that H 2 is dissociatively absorbed on M n ͑M=V,Nb, ...͒, while CO is initially molecularly absorbed on M n clusters. Following initial molecular adsorption, CO can be dissociatively adsorbed on a metal cluster in an activated reaction by surmounting a reaction barrier.…”