Ionization efficiencies of C3H6, C4H8, C6H12, C2H6O, and C3H8O isomers

Koizumi, Hideaki; Shinsaka, Kyoji; Yoshimi, T.; Hironaka, Katsuyuki; Arai, Soichi; Ukai, Masatoshi; Morita, Makoto; Nakazawa, Hikaru; Kimura, A.; Hatano, Yoshihiko; Ito, Yoshiro; Zhang, Y.; Yagishita, Akira; Ito, Kenichi; Tanaka, Kiyoshi

doi:10.1016/1359-0197(88)90023-9

Cited by 6 publications

(3 citation statements)

References 21 publications

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“…Comparison of recorded and literature photoelectron spectra − for selected m / z = 30, 42, and 58 channels over HZSM-5 (left) and Ca/ZSM-5 (right), corresponding to various oxygenate and hydrocarbon species. Reaction conditions: 350 °C, 100 mg of the catalyst, 12.3 kPa of methanol, carrier −75 mL mL·min –1 He.…”

Section: Resultsmentioning

confidence: 99%

Ca Cations Impact the Local Environment inside HZSM-5 Pores during the Methanol-to-Hydrocarbons Reaction

et al. 2023

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The methanol-to-hydrocarbons (MTH) process is an industrially relevant method to produce valuable light olefins such as propylene. One of the ways to enhance propylene selectivity is to modify zeolite catalysts with alkaline earth cations. The underlying mechanistic aspects of this type of promotion are not well understood. Here, we study the interaction of Ca2+ with reaction intermediates and products formed during the MTH reaction. Using transient kinetic and spectroscopic tools, we find strong indications that the selectivity differences between Ca/ZSM-5 and HZSM-5 are related to the different local environment inside the pores due to the presence of Ca2+. In particular, Ca/ZSM-5 strongly retains water, hydrocarbons, and oxygenates, which occupy as much as 10% of the micropores during the ongoing MTH reaction. This change in the effective pore geometry affects the formation of hydrocarbon pool components and in this way directs the MTH reaction toward the olefin cycle.

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Section: Resultsmentioning

confidence: 99%

Ca Cations Impact the Local Environment inside HZSM-5 Pores during the Methanol-to-Hydrocarbons Reaction

et al. 2023

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“…37 Again in this isomeric pair of flames, differences in the molecular-weight growth pathways can be discerned. One key difference between the two flames is the larger concentration of allyl 50 of cis-2-butene (trans-2-butene is assumed to be similar), 69 shown as the dashed line in Fig. 7.…”

Section: Allene and Propynementioning

confidence: 99%

“Imaging” combustion chemistry via multiplexed synchrotron-photoionization mass spectrometry

Taatjes

Hansen

Osborn

et al. 2008

Phys. Chem. Chem. Phys.

187

167

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The combination of multiplexed mass spectrometry with photoionization by tunable-synchrotron radiation has proved to be a powerful tool to investigate elementary reaction kinetics and the chemistry of low-pressure flames. In both of these applications, multiple-mass detection and the ease of tunability of synchrotron radiation make it possible to acquire full sets of data as a function of mass, photon energy, and of the physical dimension of the system, e.g. distance from the burner or time after reaction initiation. The data are in essence an indirect image of the chemistry. The data can be quantitatively correlated and integrated along any of several dimensions to compare to traditional measurements such as time or distance profiles of individual chemical species, but it can also be directly interpreted in image form. This perspective offers an overview of flame chemistry and chemical kinetics measurements that combine tunable photoionization with multiple-mass detection, emphasizing the overall insight that can be gained from multidimensional data on these systems. The low-pressure flame apparatus is capable of providing isomer-resolved mass spectra of stable and radical species as a function of position in the flame. The overall chemical structure of the flames can be readily seen from images of the evolving mass spectrum as distance from the burner increases, with isomer-specific information given in images of the photoionization efficiency. Several flames are compared in this manner, with a focus on identification of global differences in fuel-decomposition and soot-formation pathways. Differences in the chemistry of flames of isomeric fuels can be discerned. The application of multiplexed synchrotron photoionization to elementary reaction kinetics permits identification of time-resolved isomeric composition in reacting systems. The power of this technique is illustrated by the separation of direct and dissociative ionization signals in the reaction of C(2)H(5) with O(2); by the resolution of isomeric products in reactions of the ethynyl (C(2)H) radical; and by preliminary observation of branching to methyl + propargyl products in the self-reaction of vinyl radicals. Finally, prospects for future research using multiplexed photoionization mass spectrometry are explored.

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“…They also reported on the formation of fragment ions C 3 H 5 + , CH 2 OH + , CH 3 CHOH + , and C 2 H 5 + at appearance energies of 11.6, 11.7, 11.8, and 12.5 eV, respectively. Later, Koizumi et al and Cool et al remeasured the low-energy part of the photoionization efficiency curves with a view to obtain absolute photoionization cross sections to aid combustion diagnostics.…”

Section: Introductionmentioning

confidence: 99%

Dissociative Photoionization of Diethyl Ether

et al. 2015

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The dissociative photoionization of internal energy selected diethyl ether ions was investigated by imaging photoelectron photoion coincidence spectroscopy. In a large, 5 eV energy range Et2O(+) cations decay by two parallel and three sequential dissociative photoionization channels, which can be modeled well using statistical theory. The 0 K appearance energies of the CH3CHOCH2CH3(+) (H-loss, m/z = 73) and CH3CH2O═CH2(+) (methyl-loss, m/z = 59) fragment ions were determined to be 10.419 ± 0.015 and 10.484 ± 0.008 eV, respectively. The reemergence of the hydrogen-loss ion above 11 eV is attributed to transition-state (TS) switching, in which the second, outer TS is rate-determining at high internal energies. At 11.81 ± 0.05 eV, a secondary fragment of the CH3CHOCH2CH3(+) (m/z = 73) ion, protonated acetaldehyde, CH3CH═OH(+) (m/z = 45) appears. On the basis of the known thermochemical onset of this fragment, a reverse barrier of 325 meV was found. Two more sequential dissociation reactions were examined, namely, ethylene and formaldehyde losses from the methyl-loss daughter ion. The 0 K appearance energies of 11.85 ± 0.07 and 12.20 ± 0.08 eV, respectively, indicate no reverse barrier in these processes. The statistical model of the dissociative photoionization can also be used to predict the fractional ion abundances in threshold photoionization at large temperatures, which could be of use in, for example, combustion diagnostics.

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Ionization efficiencies of C3H6, C4H8, C6H12, C2H6O, and C3H8O isomers

Cited by 6 publications

References 21 publications

Ca Cations Impact the Local Environment inside HZSM-5 Pores during the Methanol-to-Hydrocarbons Reaction

Ca Cations Impact the Local Environment inside HZSM-5 Pores during the Methanol-to-Hydrocarbons Reaction

“Imaging” combustion chemistry via multiplexed synchrotron-photoionization mass spectrometry

Dissociative Photoionization of Diethyl Ether

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