Bromine and iodine for selective partial oxidation of propane and methane

Upham, D. Chester; Kristoffersen, Henrik H.; Snodgrass, Zachary R.; Gordon, Michael J.; Metiu, Horia; McFarland, Eric W.

doi:10.1016/j.apcata.2019.05.003

Cited by 9 publications

(8 citation statements)

References 55 publications

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“…This can be easily explained by the higher exothermicity (ΔG 0 = −22.3 kcal/mol) and lower activation barrier (E a = 4.1 kcal/mol, vide infra) of the NBS reaction relative to those of elemental bromine (ΔG 0 = −7.7 kcal/mol, E a = 18.7 kcal/mol). 24 To elucidate the mechanism of this bromination reaction, the control experiments were conducted, and the proposed mechanism is shown in Figure 2. The solar light filtering experiment revealed that the wavelength in the range of 290− 320 nm is mainly responsible for this photochemical process (Supporting Information section pS20).…”

Section: Resultsmentioning

confidence: 99%

“…In contrast, the reaction of elemental bromine (entry 6, Table ) under otherwise identical conditions afforded only 8% conversion of bromine. This can be easily explained by the higher exothermicity (Δ G 0 = −22.3 kcal/mol) and lower activation barrier ( E a = 4.1 kcal/mol, vide infra ) of the NBS reaction relative to those of elemental bromine (Δ G 0 = −7.7 kcal/mol, E a = 18.7 kcal/mol) …”

Section: Resultsmentioning

confidence: 99%

“…This, however, inevitably leads to very low methane conversion, which is uninspiring for industry. For milder oxidants, including I 2 , H 2 O, , CO 2 , − etc., however, the reaction becomes highly endothermic, and higher temperature as well as excess methane loading is required to provide a thermodynamic driving force for the high conversion of the oxidant. This leads to energy-intensive processes (700–1000 °C), such as commercialized syngas technology. ,,, Improvement strategies solely based on catalyst design are not sufficient to address this pair of inherent contradictions, as catalyst controls only the kinetic factors …”

Section: Introductionmentioning

confidence: 99%

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Methane Activation with N-Haloimides

Huo

et al. 2020

Ind. Eng. Chem. Res.

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Most thermochemical methane upgrading technologies suffer from intense energy consumption and low methane conversion due to the high energy barrier and the unfavorable thermodynamics of methane reactions. We developed a photochemical variant of methane halogenation reaction that requires minimum energy input by harnessing solar energy for methane activation and by reacting methane with N-haloimides that generate more oxidative and reactive N-centered imidyl radicals upon excitation. The reaction with N-bromosuccinimide (NBS) afforded methyl and methylene bromides with a selectivity toward methyl bromide of up to 92% at room temperature and atmospheric pressure. A minimum methane loading of 5 equiv relative to N-haloimides furnished results similar to those obtained in the presence of a large excess of methane. A good volumetric productivity of approximately 5 kg (CH3Br)·m–3·h–1 was achieved. Interestingly, the first selective iodination of methane at a moderate temperature (35–80 °C) to give methyl iodide with 84–96% selectivity was achieved with N-iodosuccinimide (NIS) and N-iodophthalimide.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Methane Activation with N-Haloimides

Huo

et al. 2020

Ind. Eng. Chem. Res.

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“…Upham et al [36] investigated methane halogenation using iodine and bromine in the gas phase. They also constructed a microkinetic model with rate constants compiled by the National Institute of Science and Technology (NIST) and some were calculated from experimental data.…”

Section: Of 31mentioning

confidence: 99%

A Review of Methane Activation Reactions by Halogenation: Catalysis, Mechanism, Kinetics, Modeling, and Reactors

et al. 2020

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Methane is the central component of natural gas, which is globally one of the most abundant feedstocks. Due to its strong C–H bond, methane activation is difficult, and its conversion into value-added chemicals and fuels has therefore been the pot of gold in the industry and academia for many years. Industrially, halogenation of methane is one of the most promising methane conversion routes, which is why this paper presents a comprehensive review of the literature on methane activation by halogenation. Homogeneous gas phase reactions and their pertinent reaction mechanisms and kinetics are presented as well as microkinetic models for methane reaction with chlorine, bromine, and iodine. The catalysts for non-oxidative and oxidative catalytic halogenation were reviewed for their activity and selectivity as well as their catalytic action. The highly reactive products of methane halogenation reactions are often converted to other chemicals in the same process, and these multi-step processes were reviewed in a separate section. Recent advances in the available computational power have made the use of the ab initio calculations (such as density functional theory) routine, allowing for in silico calculations of energy profiles, which include all stable intermediates and the transition states linking them. The available literature on this subject is presented. Lastly, green processes and the production of fuels as well as some unconventional methods for methane activation using ultrasound, plasma, superacids, and light are also reviewed.

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“…[ 3 ] The direct methane conversion in the industry needs harsh reaction conditions (high temperature > 900 K and pressure > 2.5 bar) that are both energy and capital intensive. [ 4 ] It is possible to directly oxidize CH 4 into oxygenated products at temperatures below 500 K, whereas expensive oxidants, such as H 2 O 2 , NO x , and oleum, are needed. [ 5 ] The in situ generation of active oxidizing species in the electrochemical procedure is an alternative solution.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Methane Conversion

et al. 2021

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Methane, as an earth‐abundant C1 resource, is a greenhouse gas as well as a key building block in the chemical industry. Electrochemical conversion of methane into fuels and valuable chemicals represents an attractive promise toward carbon neutralization and reducing CO2 emission in industrial methane reforming. To overcome the catalyst degradation and energy cost problems, it is critical to activate the CH bonds in methane effectively to operate under ambient conditions, while without the cost of product selectivity. This review focuses on catalyst structures and system design strategies in recent developments of electrocatalytic methane conversion progresses. The combination of electro‐, thermo‐, and photocatalytic methods can enable complementary and enhanced activities, as well as new insights in reaction conditions and mechanisms.

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Bromine and iodine for selective partial oxidation of propane and methane

Cited by 9 publications

References 55 publications

Methane Activation with N-Haloimides

Methane Activation with N-Haloimides

A Review of Methane Activation Reactions by Halogenation: Catalysis, Mechanism, Kinetics, Modeling, and Reactors

Electrochemical Methane Conversion

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