15932-89-5Relevant articles and documents
Single Chromium Atoms Supported on Titanium Dioxide Nanoparticles for Synergic Catalytic Methane Conversion under Mild Conditions
Shen, Qikai,Cao, Changyan,Huang, Runkun,Zhu, Lei,Zhou, Xin,Zhang, Qinghua,Gu, Lin,Song, Weiguo
, p. 1216 - 1219 (2020)
Direct conversion of methane to value-added chemicals with high selectivity under mild conditions remains a great challenge in catalysis. Now, single chromium atoms supported on titanium dioxide nanoparticles are reported as an efficient heterogeneous catalyst for direct methane oxidation to C1 oxygenated products with H2O2 as oxidant under mild conditions. The highest yield for C1 oxygenated products can be reached as 57.9 mol molCr?1 with selectivity of around 93 % at 50 °C for 20 h, which is significantly higher than those of most reported catalysts. The superior catalytic performance can be attributed to the synergistic effect between single Cr atoms and TiO2 support. Combining catalytic kinetics, electron paramagnetic resonance, and control experiment results, the methane conversion mechanism was proposed as a methyl radical pathway to form CH3OH and CH3OOH first, and then the generated CH3OH is further oxidized to HOCH2OOH and HCOOH.
Identification of organic peroxides in the oxidation of C1-C3 alkanes
Qi,Zhang,Chen,Shao,Tang,Hu
, p. 1213 - 1221 (1999)
Formation of organic peroxides in oxidation of C1-C3 alkanes initiated by C1 atoms in O2-N2 mixtures at 760 torr and 298 K was studied with FT-IR and HPLC method in laboratory. Methyl hydroperoxide (MHP) and ethyl hydroperoxide (EHP) were the main peroxide products and formed early in the oxidation process. Hydroxymethyl hydroperoxide (HOCH2OOH, HMHP) was identified in the reaction systems. Other two types of peroxides detected were peroxyacetic acid (CH3C(O)OOH, PAA) and dimethyl peroxide (C-H3OOCH3, DMP). In addition, more than seven peroxide products were not identified. The finding of HMHP in the system indicated that Criegee biradical CH2OO probably was an intermediate in the process of oxidation of alkanes. The results implied that oxidation of alkanes may have a significant contribution to organic peroxides in the troposphere.
Formation mechanism of peroxides in reactions of cyclic olefins with ozone in air
Hatakeyama, Shiro,Sivanesan, Subramanian,Urabe, Taichiro
, p. 1248 - 1249 (2001)
We carried out reactions of methyl-substituted cyclohexenes and α-pinene with ozone in air and elucidated the mechanisms of formation of the minor products (peroxides and formic acid). Peroxyacetic acid was formed only from the cyclohexenes with a methyl group on the double bond, whereas formic acid was produced in higher yields from the cyclohexenes without a methyl group on the double bond. These differences in product yields allowed us to elucidate the mechanism of formation of the products.
Room-Temperature Methane Conversion by Graphene-Confined Single Iron Atoms
Cui, Xiaoju,Li, Haobo,Wang, Yan,Hu, Yuanli,Hua, Lei,Li, Haiyang,Han, Xiuwen,Liu, Qingfei,Yang, Fan,He, Limin,Chen, Xiaoqi,Li, Qingyun,Xiao, Jianping,Deng, Dehui,Bao, Xinhe
supporting information, p. 1902 - 1910 (2018/06/20)
Direct conversion of methane to high-value-added chemicals is a major challenge in catalysis, which usually requires high-energy input to overcome the reaction barrier. We report that graphene-confined single Fe atoms can be used as an efficient non-precious catalyst to directly convert methane to C1 oxygenated products at room temperature. A series of graphene-confined 3d transition metals (Mn, Fe, Co, Ni, and Cu) were screened, yet only single Fe atoms could catalyze the methane conversion. Combining in operando time-of-flight mass spectrometry, 13C nuclear magnetic resonance, and density functional theory calculations, we found that methane conversion proceeds on the O–FeN4–O active site along a radical pathway to produce CH3OH and CH3OOH first, and then the generated CH3OH can be further catalyzed to form HOCH2OOH and HCOOH at room temperature. Methane from natural gas and shale gas is one of the most promising feedstocks because of its high reserves and low price. The selective activation and orientable conversion of methane are considered the “holy grail” in catalysis. Because of the highly stable C–H bond, methane conversion usually requires high temperatures to overcome the high reaction barrier. However, the high-temperature reaction is not favorable for industrial application. Despite many efforts to decrease the reaction temperature, it remains a great challenge to promote methane conversion under mild conditions, especially at room temperature. Herein, we report that graphene-confined single Fe atoms can be used as an efficient non-precious catalyst to directly convert methane to high-value-added C1 oxygenated products at room temperature (25°C), which provides a new route to understanding and designing highly efficient non-precious catalysts for methane conversion at room temperature. Graphene-confined single Fe atoms, screened out from a series of 3d transition metals (Mn, Fe, Co, Ni, and Cu), were used as an efficient non-precious catalyst to directly convert methane to C1 oxygenated products at room temperature. The unique O–FeN4–O structure formed in graphene can readily activate the C–H bond of methane along a radical pathway with a low reaction energy barrier.
