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Operando Photoelectron Photoion Coincidence Spectroscopy Unravels Mechanistic Fingerprints of Propane Activation by Catalytic Oxyhalogenation.

07:00 EST 14th January 2020 | BioPortfolio

Summary of "Operando Photoelectron Photoion Coincidence Spectroscopy Unravels Mechanistic Fingerprints of Propane Activation by Catalytic Oxyhalogenation."

Herein, we demonstrate operando photoelectron photoion coincidence (PEPICO) spectroscopy as a pivotal technique for evidencing unprecedented mechanistic insights by isomer selective radical detection within complex hydrocarbon-functionalization reaction networks, such as those of catalyzed propane oxychlorination and oxybromination. In particular, while the oxychlorination is surface-confined, we show that in oxybromination alkane activation follows a gas-phase reaction mechanism with evolved bromine and bromine radicals, favoring 2-propyl over 1-propyl radical formation, as evidenced by isomer-selective threshold photoelectron analysis. Furthermore, we provide new mechanistic insights into the cracking and coking pathways that are observed in oxybromination. The first entails propargyl radicals formation from consecutive hydrogen abstraction of propyl radicals, ultimately yielding benzene. The second originates from C-C bond cleavage in propane to ethyl and methyl radicals, which produce CH and CH, or undergo chain growth reactions, forming C-C species.

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Name: The journal of physical chemistry letters
ISSN: 1948-7185
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