Research output: Contribution to journal › Article › peer-review
Oxidation of lower alkenes by Α-oxygen (FeIII–O•−)Α on the FeZSM-5 surface: The epoxidation or the allylic oxidation? / Starokon, Eugeny V.; Malykhin, Sergei E.; Parfenov, Mikhail V. et al.
In: Molecular Catalysis, Vol. 443, 01.12.2017, p. 43-51.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Oxidation of lower alkenes by Α-oxygen (FeIII–O•−)Α on the FeZSM-5 surface: The epoxidation or the allylic oxidation?
AU - Starokon, Eugeny V.
AU - Malykhin, Sergei E.
AU - Parfenov, Mikhail V.
AU - Zhidomirov, Georgy M.
AU - Kharitonov, Alexander S.
N1 - Publisher Copyright: © 2017 Elsevier B.V.
PY - 2017/12/1
Y1 - 2017/12/1
N2 - Reactions of anion-radical α-oxygen (FeIII–O•−)α with propylene and 1-butene on sodium-modified FeZSM-5 zeolites were studied in the temperature range from −60 to 25 °C. Products were extracted from the zeolite surface and identified. It was found that main reaction pathway was the epoxides formation. Selectivity for epoxides at −60 °C was 59–64%. Other products were formed as a result of secondary transformations of epoxides on the zeolite surface. According to IR spectroscopy, the oxidation of propylene over the entire temperature range and 1-butene at −60 °C were not accompanied by the formation of (FeIII–OH)α groups, in distinction to methane oxidation. This testifies that hydrogen abstraction does not occur. In case of 1-butene reaction with α-oxygen at 25 °C, hydrogen abstraction occurred but was insignificant, ca 7%. According to DFT calculation ferraoxetane intermediate formation is preferable over hydrogen abstraction. Following decomposition of this intermediate leads to the propylene oxide (PO) formation. The results may be relevant to the low selectivity problem of the silver catalyst in propylene epoxidation and raise doubts about the presently accepted mechanism explaining an adverse effect of allylic hydrogen.
AB - Reactions of anion-radical α-oxygen (FeIII–O•−)α with propylene and 1-butene on sodium-modified FeZSM-5 zeolites were studied in the temperature range from −60 to 25 °C. Products were extracted from the zeolite surface and identified. It was found that main reaction pathway was the epoxides formation. Selectivity for epoxides at −60 °C was 59–64%. Other products were formed as a result of secondary transformations of epoxides on the zeolite surface. According to IR spectroscopy, the oxidation of propylene over the entire temperature range and 1-butene at −60 °C were not accompanied by the formation of (FeIII–OH)α groups, in distinction to methane oxidation. This testifies that hydrogen abstraction does not occur. In case of 1-butene reaction with α-oxygen at 25 °C, hydrogen abstraction occurred but was insignificant, ca 7%. According to DFT calculation ferraoxetane intermediate formation is preferable over hydrogen abstraction. Following decomposition of this intermediate leads to the propylene oxide (PO) formation. The results may be relevant to the low selectivity problem of the silver catalyst in propylene epoxidation and raise doubts about the presently accepted mechanism explaining an adverse effect of allylic hydrogen.
KW - DFT
KW - NO oxidant
KW - Oxygen anion radicals
KW - Propylene epoxidation
KW - α-oxygen
KW - GAS-PHASE EPOXIDATION
KW - PROPYLENE EPOXIDATION
KW - ACTIVE-SITES
KW - ANION-RADICALS
KW - alpha-oxygen
KW - NITROUS-OXIDE
KW - IRON-OXIDE
KW - METHANE
KW - N2O oxidant
KW - ETHYLENE EPOXIDATION
KW - N2O DECOMPOSITION
KW - DENSITY-FUNCTIONAL THEORY
UR - http://www.scopus.com/inward/record.url?scp=85033391527&partnerID=8YFLogxK
U2 - 10.1016/j.mcat.2017.09.017
DO - 10.1016/j.mcat.2017.09.017
M3 - Article
AN - SCOPUS:85033391527
VL - 443
SP - 43
EP - 51
JO - Molecular Catalysis
JF - Molecular Catalysis
SN - 2468-8231
ER -
ID: 9409613